MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Research Letters in Physics' source. Thu, 09 Feb 2012 20:29:31 +0100 http://www.medworm.com/index.php?rid=5542426&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fogi%2F2011%2F548327%2Fabs%2F Conclusions. Cesarean-related thromboembolic events were reduced in our study population due to the thromboprophylactic measures taken. Thromboprophylaxis with 3500 IU bemiparin once daily for 5 days following cesarean was sufficient to avoid thromboembolic events. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=5542426 Mon, 26 Dec 2011 13:37:27 +0100 5542426 http://www.medworm.com/index.php?rid=5156288&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijrc%2F2011%2F430808%2F As reconfigurable devices' capacities and the complexity of applications that use them increase, the need for self-reliance of deployed systems becomes increasingly prominent. Organic computing paradigms have been proposed for fault-tolerant systems because they promote behaviors that allow complex digital systems to adapt and survive in demanding environments. In this paper, we develop a sustainable modular adaptive redundancy technique (SMART) composed of a two-layered organic system. The hardware layer is implemented on a Xilinx Virtex-4 Field Programmable Gate Array (FPGA) to provide self-repair using a novel approach called reconfigurable adaptive redundancy system (RARS). The software layer supervises the organic activities on the FPGA and extends the self-healing capabilities th... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=5156288 Thu, 25 Aug 2011 09:34:58 +0100 5156288 http://www.medworm.com/index.php?rid=4669724&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fprt%2F2011%2F934932%2F Although the number of U.S. hospitals offering an acute pain service (APS) is increasing, the typical structure remains unknown. This survey was undertaken to describe the structure and function of the APS in U.S. hospitals only. We contacted 200 non-teaching and 101 teaching U.S. hospitals. The person in charge of postoperative pain management completed and returned the survey. Seventy-four percent of responding hospitals had an organized APS. An APS was significantly more formally organized in academic/teaching hospitals when compared to non-teaching hospitals. Pain assessments included “pain at rest” (97%), “pain on activity” (63%), and reassessment after pain therapy intervention (88.8%). Responding hospitals utilized postoperative pain proto... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4669724 Sun, 03 Apr 2011 14:35:12 +0100 4669724 http://www.medworm.com/index.php?rid=4669723&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fmis%2F2011%2F671308%2F Osteoarthritis (OA) is a progressive, debilitating disease that is increasing in prevalence. The pathogenesis of OA is likely multifactorial but ultimately leads to progressive breakdown of collagen matrix and loss of chondrocytes. Current clinical modalities employed to evaluate cartilage health and diagnose osteoarthritis in orthopaedic surgery include, radiography, MRI, and arthroscopy. While these assessment methods can show cartilage fissuring and loss, they are limited in ability to diagnose cartilage injury and degeneration prior breakdown of the articular surface. An improved clinical ability to detect subsurface cartilage pathology is important for development and testing of chondroprotective and chondrorestorative treatments because the pathological changes following surface bre... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4669723 Sun, 03 Apr 2011 14:35:12 +0100 4669723 http://www.medworm.com/index.php?rid=4641901&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fisrn%2Fendocrinology%2F2011%2F575397%2F The aim of the study was to analyse genes typing with the use of the oligonucleotide microarray technique (HG-U133A, Affymetrix) differentiating colorectal cancer tissues from tissues assessed histopathologically as healthy ones among a panel of 91 mRNA of genes encoding proteins involved in activation of cellular signal transduction pathways by leptin. Frozen tumor specimens from 11 colon cancer patients in various stages of clinical progression of the disease in an I–IV stage scale according to the TNM staging were used in molecular tests. Among the genes participating in the cascade of signal transfer in cell activated by leptin, the following ones: AKT1, STAT3, MCL1 were qualified as differentiating stage I and II and VEGFC, CCNDI the encoding genes respectively as differentiatin... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4641901 Mon, 28 Mar 2011 17:29:47 +0100 4641901 http://www.medworm.com/index.php?rid=4511836&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F808424.html It is shown that Schrödinger's equation may be derived from three postulates. The first is a kind of statistical metamorphosis of classical mechanics, a set of two relations which are obtained from the canonical equations of particle mechanics by replacing all observables by statistical averages. The second is a local conservation law of probability with a probability current which takes the form of a gradient. The third is a principle of maximal disorder as realized by the requirement of minimal Fisher information. The rule for calculating expectation values is obtained from a fourth postulate, the requirement of energy conservation in the mean. The fact that all these basic relations of quantum theory may be derived from premises which are statistical in character is interpreted... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4511836 Thu, 24 Feb 2011 01:01:05 +0100 4511836 http://www.medworm.com/index.php?rid=4501213&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F164249.html The principle of inductively coupled plasma (ICP) and perspective of ICP development are reviewed. Multispiral coil ICP (MSC-ICP), which has the advantages of low inductance, high efficiency, and excellent uniformity, is discussed in detail. Applications to thin film processing technologies and the future prospects of ICP are also described. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4501213 Mon, 21 Feb 2011 16:54:57 +0100 4501213 http://www.medworm.com/index.php?rid=4459378&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2011%2F302164.html We investigate a nonlinear realization of the Lorentz transformation defined in 4-dimensional spacetime, and the corresponding invariant interval. This new interval is not a quadratic form in the standard Minkowski spacetime, then we search for a description where it becomes a quadratic form in an infinite dimensional vector space. In this extended space, we show how to generate two classes of nonlinear transformations, which form a group and interpret the non-linear transformation as compatible relations between atlas of a Lyra manifold. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4459378 Fri, 11 Feb 2011 00:32:35 +0100 4459378 http://www.medworm.com/index.php?rid=4445354&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2011%2F742158.html Change of the chemical potential of electrons in a GaAs-AlxGa1−xAs heterojunction was measured in magnetic fields up to 6.5 T at several temperatures from 2.17 to 12.3 K. A thermodynamic equation of state of two-dimensional electron gas well describes the experimental results. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4445354 Tue, 08 Feb 2011 00:34:13 +0100 4445354 http://www.medworm.com/index.php?rid=4360397&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2011%2F791545.html This study will provide a basis for the characterization for strength and fracture toughness of UHTC materials and provide theoretical bases and technical reserves for the UHTC materials' design and application in the field of spacecraft. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4360397 Tue, 18 Jan 2011 21:22:26 +0100 4360397 http://www.medworm.com/index.php?rid=4337283&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F749293.html The study of the evolution of the conduction band in dense gases and supercritical fluids near the critical point has been complicated by a lack of precise experimental measurements. Both photoemission from an electrode immersed in the fluid and field ionization of a molecule doped into the fluid have been used to probe solvent density effects on the energy of an excess electron as a function of fluid number density and temperature. In this perspective, we present recent experimental results that show a strong critical point effect on the minimum conduction band energy near the critical density and temperature of a fluid. We also discuss the recent development of a new theoretical model that advances our understanding of the density and temperature dependence of the conduction band minimum... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4337283 Thu, 13 Jan 2011 01:08:44 +0100 4337283 http://www.medworm.com/index.php?rid=4298396&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F341016.html A finite-time generic model to describe the behavior of real refrigeration systems is discussed. The model accounts for finite heat transfer rates, heat leaks, and friction as different sources of dissipation. The performance characteristics are cast in terms of cooling rate (r) versus coefficient of performance (w). For comparison purposes, various types of refrigeration/heat pump systems are considered: the thermoelectric refrigerator, the reverse Brayton cycle, and the reverse Rankine cycle. Although the dissipation mechanisms are different (e.g., heat leak and Joule heating in the thermoelectric refrigerator, isentropic losses in the reverse Brayton cycle, and limits arising from the equation of state in the reverse Rankine cycle), the r−w characteristic curves have a general ... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4298396 Thu, 30 Dec 2010 09:03:31 +0100 4298396 http://www.medworm.com/index.php?rid=4293417&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F681476.html In this study, the author considers an effect of impurity clustering by liquid density fluctuations as a natural mechanism for stabilizing microstructure of the colloidal solution and estimates the effect of fractal structure of colloidal particles on thermal conductivity of water. The results of this study may be useful for motivating choosing the composition of heat-transfer suspension and developing technology for making the appropriate nanofluid. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4293417 Wed, 29 Dec 2010 04:17:59 +0100 4293417 http://www.medworm.com/index.php?rid=4264635&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F203497.html Based on the weakest bound electron potential model theory, the Rydberg energy levels and quantum defects of nsS21/2(n=8--50), ndD23/2(n=6--50), and ndD25/2(n=6--50) spectrum series for francium atom are calculated. The calculated results are in excellent agreement with the 74 known experimentally measured levels (the absolute difference is less than 0.03 cm-1) and 58 energy levels for highly excited states are predicted. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4264635 Sat, 18 Dec 2010 15:07:59 +0100 4264635 http://www.medworm.com/index.php?rid=4252611&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F284231.html We deal with a 2D half occupied square lattice with repulsive interactions between first and second neighboring particles. Despite the intensive studies of the present model the central point of the phase diagram for which the ratio of the two interaction strengths R=JSN/JFN=0.5 is still open. In the present paper we show, using standard Monte Carlo calculations, that the situation corresponds to a phase of mixed ordered structures quantified by an “algebraic” order parameter defined as the sum of densities of the existing ordered clusters. The introduced grandeur also characterizes the transitions towards the known pure ordered phases for the other values of R as mentioned by the agreement of our results with those of the literature. The computation of the Cowley short range o... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4252611 Mon, 13 Dec 2010 14:25:53 +0100 4252611 http://www.medworm.com/index.php?rid=4252610&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F201730.html Image fields generated by a bunch of charged particles between two parallel perfectly conducting plates are studied in detail. We derive exact analytical expressions for external fields of a charged relativistic bunch with a circular cross-section. Summation of image fields by the direct method invented by Laslett allows the infinite series to be represented in terms of elementary trigonometric functions. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=4252610 Mon, 13 Dec 2010 14:25:53 +0100 4252610 http://www.medworm.com/index.php?rid=3972511&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F645106.html A photonic analogue of Klein tunneling (KT), that is, of the exotic property of relativistic electrons to pass a large repulsive and sharp potential step, is proposed for pulse propagation in a nonuniform fiber Bragg grating with an embedded chirped region. KT can be simply observed as the opening of a transmission window inside the grating stop band, provided that the impressed chirp is realized over a length of the order of the analogue of the Compton wavelength. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=3972511 Thu, 16 Sep 2010 08:57:05 +0100 3972511 http://www.medworm.com/index.php?rid=3511108&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F120672.html A comparative study between effects of Mn and Al on the properties of ZnO varistor sintered at 1200C∘ is investigated by XRD, SEM hardness, and I-V measurements. Although both Mn and Al do not influence the well-known peaks related to wurtzite structure of ZnO ceramics, some other unknown peaks could be formed at higher doping content (≥0.10). Also, the shape and size of grains are clearly different for both dopants. Average crystalline diameters, deduced from XRD analysis, are between 42 nm and 62 nm, which are 50 times lower than those obtained from SEM micrographs, while the oxygen vacancies deduced from EDAX analysis, are gradually decreased by doping content for both dopants. Interestingly, the values of breakdown field, nonlinear coefficient and barrie... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=3511108 Wed, 28 Apr 2010 16:17:02 +0100 3511108 http://www.medworm.com/index.php?rid=3254027&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F493478.html We study the dynamics of transverse oscillations of a suspended carbon nanotube into which electron current is injected from the tip of a scanning tunneling microscope (STM). In this case the correlations between the displacement of the nanotube and its charge state, determined by the position-dependent electron tunneling rate, can lead to a “shuttle-like” instability for the transverse vibrational modes. We find that selective excitation of a specific mode can be achieved by an accurate positioning of the STM tip. This result suggests a feasible way to control the dynamics of this nano-electromechanical system (NEMS) based on the “shuttle instability.” (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=3254027 Tue, 09 Feb 2010 16:35:08 +0100 3254027 http://www.medworm.com/index.php?rid=3047833&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2010%2F103538.html We performed a two-variable canonical transformation on the time momentum operator, and without loss of generality we carried out a three-variable transformation on the coordinate and momentum space operators to trivialize the Hamiltonian operator of the system. Fortunately, this operation separates the time-coordinate and space coordinate naturally, and the wave function of the time-dependent Harmonic Oscillator is evaluated via the generator. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=3047833 Wed, 02 Dec 2009 16:11:36 +0100 3047833 http://www.medworm.com/index.php?rid=2934359&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F286546.html With the continued scaling of the SiO2 thickness below 2 nm in CMOS devices, a large direct-tunnelling current flow between the gate electrode and silicon substrate is greatly impacting device performance. Therefore, higher dielectric constant materials are desirable for reducing the gate leakage while maintaining transistor performance for very thin dielectric layers. Despite its not very high dielectric constant (∼10), Al2O3 has emerged as one of the most promising high-k candidates in terms of its chemical and thermal stability as its high-barrier offset. In this paper, a theoretical study of the physical and electrical properties of Al2O3 gate dielectric is reported including I(V) and C(V) characteristics. By using a stack of Al2O3/SiO2 with an appropriate equivalent oxid... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934359 Wed, 28 Oct 2009 16:13:05 +0100 2934359 http://www.medworm.com/index.php?rid=2934358&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F148505.html A type of nanopinhole-based plasmonic structure is presented. It can realize superfocusing within micron-scale propagation distance with spatial resolution beyond diffraction limit. Cut-off wavelength effect is highlighted for understanding how periodicity distribution of the nanopinholes influences transmission and focusing through the structure. Redshift peak transmission occurs while the periodicity increases. In addition, focusing property of the plasmonic structures is analyzed for the monochromatic illumination with different incident wavelengths ranging from 400 nm to 750 nm. The easy fabrication and high focusing performance of the proposed structures may be used in data storage devices, bioimaging, and nanolithography. (Source: Research Letters in Physics... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934358 Wed, 28 Oct 2009 16:13:05 +0100 2934358 http://www.medworm.com/index.php?rid=2934357&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F135289.html Many heat and mass transport problems involve particle-fluid systems, where the assumption of Stokes flow provides a very good approximation for representing small particles embedded within a viscous, incompressible fluid characterizing the steady, creeping flow. The present work is concerned with some interesting practical aspects of the theoretical analysis of Stokes flow in spheroidal domains. The stream function ψ, for axisymmetric Stokes flow, satisfies the well-known equation E4ψ=0. Despite the fact that in spherical coordinates this equation admits separable solutions, this property is not preserved when one seeks solutions in the spheroidal geometry. Nevertheless, defining some kind of semiseparability, the complete solution for ψ in spheroidal coordinates ha... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934357 Wed, 28 Oct 2009 16:13:05 +0100 2934357 http://www.medworm.com/index.php?rid=2934356&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F592869.html Contradictory to the widespread perception, storage ring free-electron lasers with substantial net gain can generate peak lasing power reaching GW levels in the so-called superpulse mode. This power level is sufficient for studies of nonlinear processes and efficient intracavity harmonic generation. This letter describes the physics of the superpulses and a phase-space refreshment in the electron beam responsible for this phenomenon. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934356 Wed, 28 Oct 2009 16:13:05 +0100 2934356 http://www.medworm.com/index.php?rid=2934355&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F293517.html The structural, elastic, and electronic properties of the hard material ReB2 have been investigated by means of density functional theory. The calculated equilibrium structural parameters of ReB2 are in agreement with the experimental results. Our result of bulk modulus shows that it is a low compressible material. Furthermore, the elastic anisotropy is discussed by investigating the elastic stiffness constants. The charge density and the electronic properties indicate that the covalent bonding of Re-B and B-B plays an important role in formation of a hard material. The good metallicity and hardness of ReB2 might serve as hard conductors. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934355 Wed, 28 Oct 2009 16:13:05 +0100 2934355 http://www.medworm.com/index.php?rid=2934354&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F570167.html As it is well known, a quantum system depending on parameters exhibits the (geometric) Berry phase when parameters are varying in the adiabatic limit. A generalization of the Berry phase is given in the present paper for a nonadiabatic change of parameters, which leads to quantum transitions in the system. This generalization is applied to noninertial motions and it is shown that such motions may induce quantum transitions for a system in an external field governed by Schrodinger's equation. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934354 Wed, 28 Oct 2009 16:13:05 +0100 2934354 http://www.medworm.com/index.php?rid=2934353&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F837503.html We report on the observation of quantum confinement effects and the influence of surface-related states due to the formation of nanograins on ultrashort relaxation near the direct critical points of silicon nanofilms following UV-excitation. Direct photoexcitation of the samples in the vicinity of the Γ critical points of the first Brillouin zone has been achieved using femtosecond pulses in the spectra range of 290–400 nm. Transient absorption measurements show a substantial enhancement of state filling with decreasing the film thickness down to 5 nm due to quantum confinement in the z-direction. Furthermore, the state filling of surface-related states of nanograins suggests that t... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934353 Wed, 28 Oct 2009 16:13:05 +0100 2934353 http://www.medworm.com/index.php?rid=2934352&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F157070.html Calculation of magnetization of the ternary single crystal compound NdRh2Ge2 has been carried out by using the wave-like molecular field model to explain the complex magnetic behavior. The field-induced magnetic structures having the propagation vectors, Q2=(0,0,39/40), Q3=(0,0,35/40), Q4=(0,0,31/40), and Q5=(0,0,0/40) (= the field-induced ferromagnetic phase) were proposed. Calculation on the basis of these structures and the antiferromagnetic phase with Q1=(0,0,1) well reproduces the experimental magnetization processes and H-T magnetic phase diagram. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934352 Wed, 28 Oct 2009 16:13:05 +0100 2934352 http://www.medworm.com/index.php?rid=2934351&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F891324.html Using a localized laser-heating method to allow the use of system size as a control parameter, we experimentally investigate, using liquid-crystal electroconvection with soft boundary conditions, the onset of spatial temporal chaos (STC) with increasing system size. We find that temporal periodicity is significantly quenched as the system size increases. The increase of the fourth moment (kurtosis) of the temporal Fourier transform provides a very useful quantitative measure of the loss of temporal periodicity (hence the onset of STC) as the pattern size increases, and also provides a simple means for determining a natural chaotic length scale. This length scale is comparable to the length of vertical rows observed in the original pattern. Our experiments, thus, imply that there are well-d... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934351 Wed, 28 Oct 2009 16:13:05 +0100 2934351 http://www.medworm.com/index.php?rid=2934350&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F786939.html We performed numerical studies of differential gain in a coupled quantum well structures built from InGaAsN. Differential gain in In0.38Ga0.62As1_yNy/GaAs quantum well structures was determined and analyzed. A 10-band k_p Hamiltonian matrix was used in the calculations and solved self-consistently with Poisson's equation. The effect of Nitrogen composition and barrier thickness on differential gain has been determined. The influence of Nitrogen composition on differential gain is significant whereas barrier effects are modest. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934350 Wed, 28 Oct 2009 16:13:05 +0100 2934350 http://www.medworm.com/index.php?rid=2934349&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F168231.html This letter focuses on studying a new energy-work relationship numerical integration scheme of nonconservative Hamiltonian systems. The signal-stage, multistage, and parallel composition numerical integration schemes are presented for this system. The high-order energy-work relation scheme of the system is constructed by a parallel connection of n multistage scheme of order 2 which its order of accuracy is 2n. The connection, which is discrete analog of usual case, between the change of energy and work of nonconservative force is obtained for nonconservative Hamiltonian systems.This letter also shows that the more the stages of the schemes are, the less the error rate of the scheme is for nonconservative Hamiltonian systems. Finally, an applied example is discussed to illustrate these resu... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934349 Wed, 28 Oct 2009 16:13:05 +0100 2934349 http://www.medworm.com/index.php?rid=2934348&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F434936.html Light emitting diodes made out of inverse spin valves of a ferromagnetic half metal sandwiched between two nonmagnetic metals are proposed. Based on a giant spin-dependent chemical potential difference created under an external bias, the inverse spin valves are possible to emit light when electrons with the higher chemical potential flip their spins and become the electrons of the opposite spin with the lower chemical potential. The frequency of this type of light emitting diodes is tunable by the bias. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934348 Wed, 28 Oct 2009 16:13:05 +0100 2934348 http://www.medworm.com/index.php?rid=2934347&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F717414.html Thin disk laser is analyzed, assuming that the heat is drained in the same direction, as the optical pulse, withdrawing the stored energy, comes. Amplified spontaneous emission, the background loss, and overheating are taken into account with simple model. The scaling laws of the basic parameters are deduced. For the case of fixed repetition rate, the upper bound of thickness is obtained. Key parameters are suggested. The key energy parameter is promoted as criterion for evaluation of different laser materials for the high energy, high mean power disk lasers. The maximum energy per active element is estimated. For the scaling up the power and/or energy withdrawn from a single active element, the background loss should scale down inversely proportional to the cube of the background loss. Th... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934347 Wed, 28 Oct 2009 16:13:05 +0100 2934347 http://www.medworm.com/index.php?rid=2934346&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F237023.html Formation of nanocrystalline rare earth was prepared by solgel route, using tetra-ethoxysilane and Nd (NO3)3 as precursor materials and HCl as a catalyst. The prepared samples were submitted to thermal treatments at temperature 500∘C (5 hours) and 800∘C (10 hours). Structural changes were investigated by XRD, FTIR spectroscopy, and SEM. At 800∘C (10 hours) resulted in the formation of cubic Nd2O3 nanocrystallites with average size ∼ 20 nm. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934346 Wed, 28 Oct 2009 16:13:05 +0100 2934346 http://www.medworm.com/index.php?rid=2934345&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F749305.html Specific features of the charge-transfer (CT) states and O2p→Cr3d transitions in the octahedral (CrO6)9− complex are considered in the cluster approach. The reduced matrix elements of the electric-dipole transition operator are calculated on many-electron wave functions of the complex corresponding to the initial and final states of a CT transition. Modeling the optic spectrum of chromites has yielded a complicated CT band. The model spectrum is in satisfactory agreement with experimental data which demonstrates the limited validity of the generally accepted concept of a simple structure of CT spectra. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934345 Wed, 28 Oct 2009 16:13:05 +0100 2934345 http://www.medworm.com/index.php?rid=2934344&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F249402.html Samples of general formula 4AgI-(1-x)PbI2-2xCuI, x=0–0.4, have been prepared and investigated by XRD, DSC, and temperature-dependent conductivity studies. X-ray diffractograms showed the presence of binary system consisting of AgI and PbI2 in the sample x=0. Cu-substituted samples showed very similar diffractograms to that of the pure compound which indicates that no effect for the substitution on the nature of the binary system. DSC curves showed the presence of phase transition whose temperature increased with Cu+ ratio in the system. Ionic conductivity measurements confirmed the occurrence of the phase transition and showed that the high temperature phase is superionic conducting, whose conductivity increases with the increasing Cu+ amount in the system. (Source: Research Letter... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934344 Wed, 28 Oct 2009 16:13:05 +0100 2934344 http://www.medworm.com/index.php?rid=2934343&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F681397.html Vertically stacked InAs/InP columnar quantum dots (CQDs) for polarization insensitive semiconductor amplifier in telecommunications applications are studied theoretically. An axial model is used to predict mechanical, electronic, and optical properties of these CQDs. A crossover from a dominant transverse electric (TE) optical ground state absorption to a dominant transverse magnetic (TM) absorption is predicted for a number of layers equal to about 9 in good agreement with the experiment. The weight of the light hole component of the valence band ground state increases as a function of the number of layers. The change of the TE/TM polarization ratio is also associated to a symmetry change of the heavy hole component. A modification of the aspect ratio of the CQD seems to be the most impor... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934343 Wed, 28 Oct 2009 16:13:05 +0100 2934343 http://www.medworm.com/index.php?rid=2934342&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F346543.html We study the Kleinberg problem of navigation in small-world networks when the underlying lattice is stretched along a preferred direction. Extensive simulations confirm that maximally efficient navigation is attained when the length r of long-range links is taken from the distribution P(r)∼r−α, when the exponent α is equal to 2, the dimension of the underlying lattice, regardless of the amount of anisotropy, but only in the limit of infinite lattice size, L→∞. For finite size lattices we find an optimal α(L) that depends strongly on L. The convergence to α=2 as L→∞ shows interesting power-law dependence on the anisotropy strength. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934342 Wed, 28 Oct 2009 16:13:05 +0100 2934342 http://www.medworm.com/index.php?rid=2934341&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F476812.html Molecular dynamic simulations have been performed to study the solid solution mechanism of Mg100-xREx (RE=Gd,Dy,Y, x=0.5,1,2,3,4  at.%). The obtained results reveal that the additions of Gd, Dy and Y increase the lattice constants of Mg-RE alloys. Also the axis ratio c/a remains unchanged with increase in temperature, restraining the occurrence of nonbasal slip and twinning. Furthermore, it is confirmed that bulk modulus of Mg alloys can be increased remarkably by adding the Gd, Dy, Y, especially Gd, because the solid solubility of Gd in Mg decrease sharply with temperature in comparison with Dy and Y. Consequently, the addition of the RE can enhance the strength of Mg-based alloys, which is in agreement with the experimental results. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934341 Wed, 28 Oct 2009 16:13:05 +0100 2934341 http://www.medworm.com/index.php?rid=2934340&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2008%2F195873.html We use a search algorithm to identify networks with enhanced linear stability properties in this account. We then analyze these networks for topological regularities that explain the source of their stability/instability. Analysis of the structure of networks with enhanced stability properties reveals that these networks are characterized by a highly skewed degree distribution, very short path-length between nodes, little or no clustering, and dissasortativity. By contrast, networks with enhanced instability properties have a peaked degree distribution with a small variance, long path-lengths between nodes, a high degree of clustering, and high assortativity. We then test the topological stability of these networks and discover that networks with enhanced stability properties are highly ro... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934340 Wed, 28 Oct 2009 16:13:05 +0100 2934340 http://www.medworm.com/index.php?rid=2934339&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F382578.html The polycrystalline samples of Pb1−xSmx (Zr0.45Ti0.55)1−x/4O3 (PSZT) (where x  =  0.00,  0.03,  0.06, and 0.09) were prepared by a high-temperature solid-state reaction technique. Preliminary X-ray structural analysis of the materials at room temperature has confirmed their formation in single-phase with tetragonal crystal structure. The temperature dependence of dielectric response of the samples at selected frequencies has exhibited their phase transition well above the room temperature. The variation of ac conductivity with temperature and the value of activation energy reveal that their conduction process is of mixed type (i.e., singly ionized in ferroelectric region and doubly ionized in paraelectric phase). ... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934339 Wed, 28 Oct 2009 16:13:05 +0100 2934339 http://www.medworm.com/index.php?rid=2934338&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F748104.html The studies of suprathermal flux at equatorial latitude for low solar activity year of 1996 (from January to December) are reported. The retarding potential analyzer (RPA) data of Indian space research organization Stretched Rohini Satellite Series-C2 (SROSS-C2) are used. The suprathermal electron flux data are chosen in the height range of 475±50 km. Seasional, latitudinal, and height variations of suprathermal flux having energy range above 30 eV along with comparisons in latitudinal variation of small energy superathermal flux of 5 eV are also reported. The data are selected during the period of local midnight to avoid contaminations from photoelectron flux and flux coming from coating of electrodes. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934338 Wed, 28 Oct 2009 16:13:05 +0100 2934338 http://www.medworm.com/index.php?rid=2934337&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F250203.html The asymptotical behavior of order parameter in confined binary mixture is considered in one-dimensional geometry. The interaction between bulk and surface forces in the mixture is investigated. Its established conditions are when the bulk spinodal decomposition may be ignored and when the main role in the process of formation of the oscillating asymptotic periodic spatiotemporal structures plays the surface-directed spinodal decomposition which is modelled by nonlinear dynamical boundary conditions. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934337 Wed, 28 Oct 2009 16:13:05 +0100 2934337 http://www.medworm.com/index.php?rid=2934336&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F594175.html The reflectivity spectra have been traditionally used to determine the thicknesses in semiconductor films. However, thicknesses of nanofilms are not easy to evaluate because the interference fringes are not visible in the transparent region. In this paper, we present a computed method based on the transfer matrix (TM) which is used to match the calculated and experimental room temperature reflectivity spectra of the ZnTe/GaAs films and to determine its thickness film values afterwards. The TM method needs only to know refraction indices and absorption coefficients as a function of wavelength for the film and the substrate. The thickness nanofilms evaluated by our method are in agreement with the values measured by ellipsometry, Rutherford backscattering spectroscopy and transmission electr... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934336 Wed, 28 Oct 2009 16:13:05 +0100 2934336 http://www.medworm.com/index.php?rid=2934335&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F410950.html We find a simple, partially altruistic mechanism that can increase global gain for a community of selfish agents. The mechanism is implied in the phenomena found in the minority game. We apply the mechanism to a two-road traffic system to maximise traffic flow. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934335 Wed, 28 Oct 2009 16:13:05 +0100 2934335 http://www.medworm.com/index.php?rid=2934334&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F298790.html Here we use the extended phase space formulation of quantum statistical mechanics proposed in an earlier work to define an extended lagrangian for Wigner's functions (WFs). The extended action defined by this lagrangian is a function of ordinary phase space variables. The reality condition of WFs is employed to quantize the extended action. The energy quantization is obtained as a direct consequence of the quantized action. The technique is applied to find the energy states of harmonic oscillator, particle in the box, and hydrogen atom as the illustrative examples. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934334 Wed, 28 Oct 2009 16:13:05 +0100 2934334 http://www.medworm.com/index.php?rid=2934333&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F832413.html The plasma screening effect is found to uncover a Cooper minimum in the photoionization cross sections from the ground state of the Li atom embedded in Debye plasma environment. The variation of the location of this minimum with Debye screening length is discussed and analyzed in terms of the instability of the ground state. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934333 Wed, 28 Oct 2009 16:13:05 +0100 2934333 http://www.medworm.com/index.php?rid=2934332&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F216373.html The amplitude and phase of 19.8 kHz signal from navigational transmitter located in North West Cape, Australia, recorded at Suva, Fiji, have been utilized to determine the waveguide mode parameters. The propagation path is mixed over land and sea having Transmitter-Receiver Great Circle Path distance 6.7 Mm. The experimental values of the parameters were found to be consistent with the theoretical values calculated using the mode theory of VLF wave propagation in the waveguide. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934332 Wed, 28 Oct 2009 16:13:05 +0100 2934332 http://www.medworm.com/index.php?rid=2934331&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F524957.html We analyse the hypothesis that the “GSI oscillations” of the K-shell electron capture decay (EC) rates of the H-like heavy ions are caused by quantum beats from a coherent state of two closely spaced ground mass-eigenstates |m′〉 and |m″〉 of decaying H-like heavy ions. We apply this mechanism to the calculation of the β+-decay rates of the H-like heavy ions and discuss the dynamics of the production of the H-like heavy ions with two closely spaced ground mass-eigenstates at GSI experiments. We show that such a mechanism cannot describe simultaneously the experimental data on both the EC-decay and β+-decay rates of the H-like heavy ions, measured at GSI. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934331 Wed, 28 Oct 2009 16:13:05 +0100 2934331 http://www.medworm.com/index.php?rid=2934330&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fphys%2F2009%2F406095.html Direct supercell approach calculations of the magnetic exchange interactions in Mn-doped ScN was carried out in the local spin density approximation by using the muffin-tin-orbital Green's function method. We found that magnetic interactions are long range interactions and affected by the randomness, band gap corrections, and carrier concentrations. Using total energy minimization approach we found that the global energy minimum of MnN is obtained for zinc-blende structure. If the compound is compressed by 6%, the energy minimum corresponds to the rock-salt structure in disagreement with the experimentally observed tetragonal distorted rock-salt structure, known as θ-phase. An isostructural phase transition for MnxSc1-xN alloys from MnN θ-phase to h-ScN phase was foun... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2934330 Wed, 28 Oct 2009 16:13:05 +0100 2934330 http://www.medworm.com/index.php?rid=2745415&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2009%2F524957.html We analyse the hypothesis that the “GSI oscillations” of the K-shell electron capture decay (EC) rates of the H-like heavy ions are caused by quantum beats from a coherent state of two closely spaced ground mass-eigenstates |m′〉 and |m″〉 of decaying H-like heavy ions. We apply this mechanism to the calculation of the β+-decay rates of the H-like heavy ions and discuss the dynamics of the production of the H-like heavy ions with two closely spaced ground mass-eigenstates at GSI experiments. We show that such a mechanism cannot describe simultaneously the experimental data on both the EC-decay and β+-decay rates of the H-like heavy ions, measured at GSI. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2745415 Sun, 30 Aug 2009 13:26:07 +0100 2745415 http://www.medworm.com/index.php?rid=2653364&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2009%2F216373.html The amplitude and phase of 19.8 kHz signal from navigational transmitter located in North West Cape, Australia, recorded at Suva, Fiji, have been utilized to determine the waveguide mode parameters. The propagation path is mixed over land and sea having Transmitter-Receiver Great Circle Path distance 6.7 Mm. The experimental values of the parameters were found to be consistent with the theoretical values calculated using the mode theory of VLF wave propagation in the waveguide. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2653364 Thu, 30 Jul 2009 12:27:20 +0100 2653364 http://www.medworm.com/index.php?rid=2597831&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2009%2F832413.html The plasma screening effect is found to uncover a Cooper minimum in the photoionization cross sections from the ground state of the Li atom embedded in Debye plasma environment. The variation of the location of this minimum with Debye screening length is discussed and analyzed in terms of the instability of the ground state. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2597831 Tue, 14 Jul 2009 12:12:32 +0100 2597831 http://www.medworm.com/index.php?rid=2468417&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F589269.html We introduce a class of potentials for which the time-dependent Schrödinger equation with position-dependent (effective) mass allows reduction to a stationary Schrödinger equation. This reduction is done by a particular point canonical transformation which preserves L2-normalizability. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468417 Wed, 10 Jun 2009 05:16:47 +0100 2468417 http://www.medworm.com/index.php?rid=2468416&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F890916.html We construct a dyon solution for the noncommutative version of the Yang-Mills-Higgs model with a ϑ-term. Extending the Noether method to the case of a noncommutative gauge theory, we analyze the effect of CP violation induced both by the ϑ-term and by noncommutativity proving that the Witten effect formula for the dyon charge remains the same as in ordinary space. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468416 Wed, 10 Jun 2009 05:16:47 +0100 2468416 http://www.medworm.com/index.php?rid=2468415&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F879017.html Using hybrid density functional theory and a relatively large basis set, the lowest energy equilibrium structure, vibrational spectrum, and natural orbital analysis were obtained for magnesium diboride clusters [(MgB2)x for x=1,2, and 3]. For comparison, boron clusters [Bx for x=2,4, and 6] were also considered. The MgB2 and (MgB2)2 showed equilibrium structures with the boron atoms in arrangements similar to what was obtained for pure boron atoms, whereas, for (MgB2)3 a different arrangement of boron was obtained. From the population analysis, large electron density in the boron atoms forming the clusters was observed. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468415 Wed, 10 Jun 2009 05:16:47 +0100 2468415 http://www.medworm.com/index.php?rid=2468414&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F746892.html Computer simulations of the radiation defects created in beryllium irradiated by fast neutrons (E>0.1 MeV) using the Geant4 and SRIM packages were carried out. The atom cascade displacements in Be at a neutron fluence of 1.6×1020 n/cm2 were determined to be 0.06 dpa and the helium concentration was calculated to be 168 appm. The concentration of L6i has been estimated to be 5% in comparison to the He concentration. Nanoscale calculations were done in 30×30×30 nm cube of fast neutron-irradiated Be. A correlation between the Be primary knock-on atom (PKA) energies and the damage cascades has been established. The final defect distributions of single vacancies, divacancies, and small vacancy clusters were examined. Our result... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468414 Wed, 10 Jun 2009 05:16:47 +0100 2468414 http://www.medworm.com/index.php?rid=2468413&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F286546.html With the continued scaling of the SiO2 thickness below 2 nm in CMOS devices, a large direct-tunnelling current flow between the gate electrode and silicon substrate is greatly impacting device performance. Therefore, higher dielectric constant materials are desirable for reducing the gate leakage while maintaining transistor performance for very thin dielectric layers. Despite its not very high dielectric constant (∼10), Al2O3 has emerged as one of the most promising high-k candidates in terms of its chemical and thermal stability as its high-barrier offset. In this paper, a theoretical study of the physical and electrical properties of Al2O3 gate dielectric is reported including I(V) and C(V) characteristics. By using a stack of Al2O3/SiO2 with an appropriate equivalent oxid... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468413 Wed, 10 Jun 2009 05:16:47 +0100 2468413 http://www.medworm.com/index.php?rid=2468412&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F148505.html A type of nanopinhole-based plasmonic structure is presented. It can realize superfocusing within micron-scale propagation distance with spatial resolution beyond diffraction limit. Cut-off wavelength effect is highlighted for understanding how periodicity distribution of the nanopinholes influences transmission and focusing through the structure. Redshift peak transmission occurs while the periodicity increases. In addition, focusing property of the plasmonic structures is analyzed for the monochromatic illumination with different incident wavelengths ranging from 400 nm to 750 nm. The easy fabrication and high focusing performance of the proposed structures may be used in data storage devices, bioimaging, and nanolithography. (Source: Research Letters in Physics... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468412 Wed, 10 Jun 2009 05:16:47 +0100 2468412 http://www.medworm.com/index.php?rid=2468411&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F135289.html Many heat and mass transport problems involve particle-fluid systems, where the assumption of Stokes flow provides a very good approximation for representing small particles embedded within a viscous, incompressible fluid characterizing the steady, creeping flow. The present work is concerned with some interesting practical aspects of the theoretical analysis of Stokes flow in spheroidal domains. The stream function ψ, for axisymmetric Stokes flow, satisfies the well-known equation E4ψ=0. Despite the fact that in spherical coordinates this equation admits separable solutions, this property is not preserved when one seeks solutions in the spheroidal geometry. Nevertheless, defining some kind of semiseparability, the complete solution for ψ in spheroidal coordinates ha... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468411 Wed, 10 Jun 2009 05:16:47 +0100 2468411 http://www.medworm.com/index.php?rid=2468410&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F592869.html Contradictory to the widespread perception, storage ring free-electron lasers with substantial net gain can generate peak lasing power reaching GW levels in the so-called superpulse mode. This power level is sufficient for studies of nonlinear processes and efficient intracavity harmonic generation. This letter describes the physics of the superpulses and a phase-space refreshment in the electron beam responsible for this phenomenon. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468410 Wed, 10 Jun 2009 05:16:47 +0100 2468410 http://www.medworm.com/index.php?rid=2468409&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F293517.html The structural, elastic, and electronic properties of the hard material ReB2 have been investigated by means of density functional theory. The calculated equilibrium structural parameters of ReB2 are in agreement with the experimental results. Our result of bulk modulus shows that it is a low compressible material. Furthermore, the elastic anisotropy is discussed by investigating the elastic stiffness constants. The charge density and the electronic properties indicate that the covalent bonding of Re-B and B-B plays an important role in formation of a hard material. The good metallicity and hardness of ReB2 might serve as hard conductors. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468409 Wed, 10 Jun 2009 05:16:47 +0100 2468409 http://www.medworm.com/index.php?rid=2468408&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F570167.html As it is well known, a quantum system depending on parameters exhibits the (geometric) Berry phase when parameters are varying in the adiabatic limit. A generalization of the Berry phase is given in the present paper for a nonadiabatic change of parameters, which leads to quantum transitions in the system. This generalization is applied to noninertial motions and it is shown that such motions may induce quantum transitions for a system in an external field governed by Schrodinger's equation. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468408 Wed, 10 Jun 2009 05:16:47 +0100 2468408 http://www.medworm.com/index.php?rid=2468407&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F837503.html We report on the observation of quantum confinement effects and the influence of surface-related states due to the formation of nanograins on ultrashort relaxation near the direct critical points of silicon nanofilms following UV-excitation. Direct photoexcitation of the samples in the vicinity of the Γ critical points of the first Brillouin zone has been achieved using femtosecond pulses in the spectra range of 290–400 nm. Transient absorption measurements show a substantial enhancement of state filling with decreasing the film thickness down to 5 nm due to quantum confinement in the z-direction. Furthermore, the state filling of surface-related states of nanograins suggests that t... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468407 Wed, 10 Jun 2009 05:16:47 +0100 2468407 http://www.medworm.com/index.php?rid=2468406&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F157070.html Calculation of magnetization of the ternary single crystal compound NdRh2Ge2 has been carried out by using the wave-like molecular field model to explain the complex magnetic behavior. The field-induced magnetic structures having the propagation vectors, Q2=(0,0,39/40), Q3=(0,0,35/40), Q4=(0,0,31/40), and Q5=(0,0,0/40) (= the field-induced ferromagnetic phase) were proposed. Calculation on the basis of these structures and the antiferromagnetic phase with Q1=(0,0,1) well reproduces the experimental magnetization processes and H-T magnetic phase diagram. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468406 Wed, 10 Jun 2009 05:16:47 +0100 2468406 http://www.medworm.com/index.php?rid=2468405&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F891324.html Using a localized laser-heating method to allow the use of system size as a control parameter, we experimentally investigate, using liquid-crystal electroconvection with soft boundary conditions, the onset of spatial temporal chaos (STC) with increasing system size. We find that temporal periodicity is significantly quenched as the system size increases. The increase of the fourth moment (kurtosis) of the temporal Fourier transform provides a very useful quantitative measure of the loss of temporal periodicity (hence the onset of STC) as the pattern size increases, and also provides a simple means for determining a natural chaotic length scale. This length scale is comparable to the length of vertical rows observed in the original pattern. Our experiments, thus, imply that there are well-d... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468405 Wed, 10 Jun 2009 05:16:47 +0100 2468405 http://www.medworm.com/index.php?rid=2468404&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F786939.html We performed numerical studies of differential gain in a coupled quantum well structures built from InGaAsN. Differential gain in In0.38Ga0.62As1_yNy/GaAs quantum well structures was determined and analyzed. A 10-band k_p Hamiltonian matrix was used in the calculations and solved self-consistently with Poisson's equation. The effect of Nitrogen composition and barrier thickness on differential gain has been determined. The influence of Nitrogen composition on differential gain is significant whereas barrier effects are modest. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468404 Wed, 10 Jun 2009 05:16:47 +0100 2468404 http://www.medworm.com/index.php?rid=2468403&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F168231.html This letter focuses on studying a new energy-work relationship numerical integration scheme of nonconservative Hamiltonian systems. The signal-stage, multistage, and parallel composition numerical integration schemes are presented for this system. The high-order energy-work relation scheme of the system is constructed by a parallel connection of n multistage scheme of order 2 which its order of accuracy is 2n. The connection, which is discrete analog of usual case, between the change of energy and work of nonconservative force is obtained for nonconservative Hamiltonian systems.This letter also shows that the more the stages of the schemes are, the less the error rate of the scheme is for nonconservative Hamiltonian systems. Finally, an applied example is discussed to illustrate these resu... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468403 Wed, 10 Jun 2009 05:16:47 +0100 2468403 http://www.medworm.com/index.php?rid=2468402&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F434936.html Light emitting diodes made out of inverse spin valves of a ferromagnetic half metal sandwiched between two nonmagnetic metals are proposed. Based on a giant spin-dependent chemical potential difference created under an external bias, the inverse spin valves are possible to emit light when electrons with the higher chemical potential flip their spins and become the electrons of the opposite spin with the lower chemical potential. The frequency of this type of light emitting diodes is tunable by the bias. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468402 Wed, 10 Jun 2009 05:16:47 +0100 2468402 http://www.medworm.com/index.php?rid=2468401&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F717414.html Thin disk laser is analyzed, assuming that the heat is drained in the same direction, as the optical pulse, withdrawing the stored energy, comes. Amplified spontaneous emission, the background loss, and overheating are taken into account with simple model. The scaling laws of the basic parameters are deduced. For the case of fixed repetition rate, the upper bound of thickness is obtained. Key parameters are suggested. The key energy parameter is promoted as criterion for evaluation of different laser materials for the high energy, high mean power disk lasers. The maximum energy per active element is estimated. For the scaling up the power and/or energy withdrawn from a single active element, the background loss should scale down inversely proportional to the cube of the background loss. Th... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468401 Wed, 10 Jun 2009 05:16:47 +0100 2468401 http://www.medworm.com/index.php?rid=2468400&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F237023.html Formation of nanocrystalline rare earth was prepared by solgel route, using tetra-ethoxysilane and Nd (NO3)3 as precursor materials and HCl as a catalyst. The prepared samples were submitted to thermal treatments at temperature 500∘C (5 hours) and 800∘C (10 hours). Structural changes were investigated by XRD, FTIR spectroscopy, and SEM. At 800∘C (10 hours) resulted in the formation of cubic Nd2O3 nanocrystallites with average size ∼ 20 nm. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468400 Wed, 10 Jun 2009 05:16:47 +0100 2468400 http://www.medworm.com/index.php?rid=2468399&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F749305.html Specific features of the charge-transfer (CT) states and O2p→Cr3d transitions in the octahedral (CrO6)9− complex are considered in the cluster approach. The reduced matrix elements of the electric-dipole transition operator are calculated on many-electron wave functions of the complex corresponding to the initial and final states of a CT transition. Modeling the optic spectrum of chromites has yielded a complicated CT band. The model spectrum is in satisfactory agreement with experimental data which demonstrates the limited validity of the generally accepted concept of a simple structure of CT spectra. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468399 Wed, 10 Jun 2009 05:16:47 +0100 2468399 http://www.medworm.com/index.php?rid=2468398&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F249402.html Samples of general formula 4AgI-(1-x)PbI2-2xCuI, x=0–0.4, have been prepared and investigated by XRD, DSC, and temperature-dependent conductivity studies. X-ray diffractograms showed the presence of binary system consisting of AgI and PbI2 in the sample x=0. Cu-substituted samples showed very similar diffractograms to that of the pure compound which indicates that no effect for the substitution on the nature of the binary system. DSC curves showed the presence of phase transition whose temperature increased with Cu+ ratio in the system. Ionic conductivity measurements confirmed the occurrence of the phase transition and showed that the high temperature phase is superionic conducting, whose conductivity increases with the increasing Cu+ amount in the system. (Source: Research Letter... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468398 Wed, 10 Jun 2009 05:16:47 +0100 2468398 http://www.medworm.com/index.php?rid=2468397&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F681397.html Vertically stacked InAs/InP columnar quantum dots (CQDs) for polarization insensitive semiconductor amplifier in telecommunications applications are studied theoretically. An axial model is used to predict mechanical, electronic, and optical properties of these CQDs. A crossover from a dominant transverse electric (TE) optical ground state absorption to a dominant transverse magnetic (TM) absorption is predicted for a number of layers equal to about 9 in good agreement with the experiment. The weight of the light hole component of the valence band ground state increases as a function of the number of layers. The change of the TE/TM polarization ratio is also associated to a symmetry change of the heavy hole component. A modification of the aspect ratio of the CQD seems to be the most impor... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468397 Wed, 10 Jun 2009 05:16:47 +0100 2468397 http://www.medworm.com/index.php?rid=2468396&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F346543.html We study the Kleinberg problem of navigation in small-world networks when the underlying lattice is stretched along a preferred direction. Extensive simulations confirm that maximally efficient navigation is attained when the length r of long-range links is taken from the distribution P(r)∼r−α, when the exponent α is equal to 2, the dimension of the underlying lattice, regardless of the amount of anisotropy, but only in the limit of infinite lattice size, L→∞. For finite size lattices we find an optimal α(L) that depends strongly on L. The convergence to α=2 as L→∞ shows interesting power-law dependence on the anisotropy strength. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468396 Wed, 10 Jun 2009 05:16:47 +0100 2468396 http://www.medworm.com/index.php?rid=2468395&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F476812.html Molecular dynamic simulations have been performed to study the solid solution mechanism of Mg100-xREx (RE=Gd,Dy,Y, x=0.5,1,2,3,4  at.%). The obtained results reveal that the additions of Gd, Dy and Y increase the lattice constants of Mg-RE alloys. Also the axis ratio c/a remains unchanged with increase in temperature, restraining the occurrence of nonbasal slip and twinning. Furthermore, it is confirmed that bulk modulus of Mg alloys can be increased remarkably by adding the Gd, Dy, Y, especially Gd, because the solid solubility of Gd in Mg decrease sharply with temperature in comparison with Dy and Y. Consequently, the addition of the RE can enhance the strength of Mg-based alloys, which is in agreement with the experimental results. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468395 Wed, 10 Jun 2009 05:16:47 +0100 2468395 http://www.medworm.com/index.php?rid=2468394&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2008%2F195873.html We use a search algorithm to identify networks with enhanced linear stability properties in this account. We then analyze these networks for topological regularities that explain the source of their stability/instability. Analysis of the structure of networks with enhanced stability properties reveals that these networks are characterized by a highly skewed degree distribution, very short path-length between nodes, little or no clustering, and dissasortativity. By contrast, networks with enhanced instability properties have a peaked degree distribution with a small variance, long path-lengths between nodes, a high degree of clustering, and high assortativity. We then test the topological stability of these networks and discover that networks with enhanced stability properties are highly ro... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468394 Wed, 10 Jun 2009 05:16:47 +0100 2468394 http://www.medworm.com/index.php?rid=2468393&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2009%2F382578.html The polycrystalline samples of Pb1−xSmx (Zr0.45Ti0.55)1−x/4O3 (PSZT) (where x  =  0.00,  0.03,  0.06, and 0.09) were prepared by a high-temperature solid-state reaction technique. Preliminary X-ray structural analysis of the materials at room temperature has confirmed their formation in single-phase with tetragonal crystal structure. The temperature dependence of dielectric response of the samples at selected frequencies has exhibited their phase transition well above the room temperature. The variation of ac conductivity with temperature and the value of activation energy reveal that their conduction process is of mixed type (i.e., singly ionized in ferroelectric region and doubly ionized in paraelectric phase). ... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468393 Wed, 10 Jun 2009 05:16:47 +0100 2468393 http://www.medworm.com/index.php?rid=2468392&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2009%2F748104.html The studies of suprathermal flux at equatorial latitude for low solar activity year of 1996 (from January to December) are reported. The retarding potential analyzer (RPA) data of Indian space research organization Stretched Rohini Satellite Series-C2 (SROSS-C2) are used. The suprathermal electron flux data are chosen in the height range of 475±50 km. Seasional, latitudinal, and height variations of suprathermal flux having energy range above 30 eV along with comparisons in latitudinal variation of small energy superathermal flux of 5 eV are also reported. The data are selected during the period of local midnight to avoid contaminations from photoelectron flux and flux coming from coating of electrodes. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468392 Wed, 10 Jun 2009 05:16:47 +0100 2468392 http://www.medworm.com/index.php?rid=2468391&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2009%2F250203.html The asymptotical behavior of order parameter in confined binary mixture is considered in one-dimensional geometry. The interaction between bulk and surface forces in the mixture is investigated. Its established conditions are when the bulk spinodal decomposition may be ignored and when the main role in the process of formation of the oscillating asymptotic periodic spatiotemporal structures plays the surface-directed spinodal decomposition which is modelled by nonlinear dynamical boundary conditions. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468391 Wed, 10 Jun 2009 05:16:47 +0100 2468391 http://www.medworm.com/index.php?rid=2468390&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2009%2F594175.html The reflectivity spectra have been traditionally used to determine the thicknesses in semiconductor films. However, thicknesses of nanofilms are not easy to evaluate because the interference fringes are not visible in the transparent region. In this paper, we present a computed method based on the transfer matrix (TM) which is used to match the calculated and experimental room temperature reflectivity spectra of the ZnTe/GaAs films and to determine its thickness film values afterwards. The TM method needs only to know refraction indices and absorption coefficients as a function of wavelength for the film and the substrate. The thickness nanofilms evaluated by our method are in agreement with the values measured by ellipsometry, Rutherford backscattering spectroscopy and transmission electr... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468390 Wed, 10 Jun 2009 05:16:47 +0100 2468390 http://www.medworm.com/index.php?rid=2468389&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2009%2F410950.html We find a simple, partially altruistic mechanism that can increase global gain for a community of selfish agents. The mechanism is implied in the phenomena found in the minority game. We apply the mechanism to a two-road traffic system to maximise traffic flow. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468389 Wed, 10 Jun 2009 05:16:47 +0100 2468389 http://www.medworm.com/index.php?rid=2468388&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Frlp%2F2009%2F298790.html Here we use the extended phase space formulation of quantum statistical mechanics proposed in an earlier work to define an extended lagrangian for Wigner's functions (WFs). The extended action defined by this lagrangian is a function of ordinary phase space variables. The reality condition of WFs is employed to quantize the extended action. The energy quantization is obtained as a direct consequence of the quantized action. The technique is applied to find the energy states of harmonic oscillator, particle in the box, and hydrogen atom as the illustrative examples. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2468388 Wed, 10 Jun 2009 05:16:47 +0100 2468388 http://www.medworm.com/index.php?rid=2374998&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2009%2F410950 We find a simple, partially altruistic mechanism that can increase global gain for a community of selfish agents. The mechanism is implied in the phenomena found in the minority game. We apply the mechanism to a two-road traffic system to maximise traffic flow. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2374998 Wed, 29 Apr 2009 16:16:42 +0100 2374998 http://www.medworm.com/index.php?rid=2363948&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2009%2F594175 The reflectivity spectra have been traditionally used to determine the thicknesses in semiconductor films. However, thicknesses of nanofilms are not easy to evaluate because the interference fringes are not visible in the transparent region. In this paper, we present a computed method based on the transfer matrix (TM) which is used to match the calculated and experimental room temperature reflectivity spectra of the ZnTe/GaAs films and to determine its thickness film values afterwards. The TM method needs only to know refraction indices and absorption coefficients as a function of wavelength for the film and the substrate. The thickness nanofilms evaluated by our method are in agreement with the values measured by ellipsometry, Rutherford backscattering spectroscopy and transmission electr... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2363948 Fri, 24 Apr 2009 19:08:42 +0100 2363948 http://www.medworm.com/index.php?rid=2191762&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2009%2F250203 The asymptotical behavior of order parameter in confined binary mixture is considered in one-dimensional geometry. The interaction between bulk and surface forces in the mixture is investigated. Its established conditions are when the bulk spinodal decomposition may be ignored and when the main role in the process of formation of the oscillating asymptotic periodic spatiotemporal structures plays the surface-directed spinodal decomposition which is modelled by nonlinear dynamical boundary conditions. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2191762 Tue, 17 Feb 2009 21:15:08 +0100 2191762 http://www.medworm.com/index.php?rid=2188561&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2009%2F748104 The studies of suprathermal flux at equatorial latitude for low solar activity year of 1996 (from January to December) are reported. The retarding potential analyzer (RPA) data of Indian space research organization Stretched Rohini Satellite Series-C2 (SROSS-C2) are used. The suprathermal electron flux data are chosen in the height range of 475±50 km. Seasional, latitudinal, and height variations of suprathermal flux having energy range above 30 eV along with comparisons in latitudinal variation of small energy superathermal flux of 5 eV are also reported. The data are selected during the period of local midnight to avoid contaminations from photoelectron flux and flux coming from coating of electrodes. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2188561 Sun, 15 Feb 2009 18:55:05 +0100 2188561 http://www.medworm.com/index.php?rid=2138606&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2009%2F382578 The polycrystalline samples of Pb1−xSmx (Zr0.45Ti0.55)1−x/4O3 (PSZT) (where x  =  0.00,  0.03,  0.06, and 0.09) were prepared by a high-temperature solid-state reaction technique. Preliminary X-ray structural analysis of the materials at room temperature has confirmed their formation in single-phase with tetragonal crystal structure. The temperature dependence of dielectric response of the samples at selected frequencies has exhibited their phase transition well above the room temperature. The variation of ac conductivity with temperature and the value of activation energy reveal that their conduction process is of mixed type (i.e., singly ionized in ferroelectric region and doubly ionized in paraelectric phase). ... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=2138606 Wed, 28 Jan 2009 12:55:12 +0100 2138606 http://www.medworm.com/index.php?rid=1999665&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F195873 We use a search algorithm to identify networks with enhanced linear stability properties in this account. We then analyze these networks for topological regularities that explain the source of their stability/instability. Analysis of the structure of networks with enhanced stability properties reveals that these networks are characterized by a highly skewed degree distribution, very short path-length between nodes, little or no clustering, and dissasortativity. By contrast, networks with enhanced instability properties have a peaked degree distribution with a small variance, long path-lengths between nodes, a high degree of clustering, and high assortativity. We then test the topological stability of these networks and discover that networks with enhanced stability properties are highly ro... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1999665 Mon, 01 Dec 2008 13:07:58 +0100 1999665 http://www.medworm.com/index.php?rid=1964782&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F346543 We study the Kleinberg problem of navigation in small-world networks when the underlying lattice is stretched along a preferred direction. Extensive simulations confirm that maximally efficient navigation is attained when the length r of long-range links is taken from the distribution P(r)∼r−α, when the exponent α is equal to 2, the dimension of the underlying lattice, regardless of the amount of anisotropy, but only in the limit of infinite lattice size, L→∞. For finite size lattices we find an optimal α(L) that depends strongly on L. The convergence to α=2 as L→∞ shows interesting power-law dependence on the anisotropy strength. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1964782 Mon, 17 Nov 2008 12:05:57 +0100 1964782 http://www.medworm.com/index.php?rid=1964781&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F476812 Molecular dynamic simulations have been performed to study the solid solution mechanism of Mg100-xREx (RE=Gd,Dy,Y, x=0.5,1,2,3,4  at.%). The obtained results reveal that the additions of Gd, Dy and Y increase the lattice constants of Mg-RE alloys. Also the axis ratio c/a remains unchanged with increase in temperature, restraining the occurrence of nonbasal slip and twinning. Furthermore, it is confirmed that bulk modulus of Mg alloys can be increased remarkably by adding the Gd, Dy, Y, especially Gd, because the solid solubility of Gd in Mg decrease sharply with temperature in comparison with Dy and Y. Consequently, the addition of the RE can enhance the strength of Mg-based alloys, which is in agreement with the experimental results. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1964781 Mon, 17 Nov 2008 12:05:57 +0100 1964781 http://www.medworm.com/index.php?rid=1826951&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F589269 We introduce a class of potentials for which the time-dependent Schrödinger equation with position-dependent (effective) mass allows reduction to a stationary Schrödinger equation. This reduction is done by a particular point canonical transformation which preserves L2-normalizability. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1826951 Thu, 25 Sep 2008 18:15:56 +0100 1826951 http://www.medworm.com/index.php?rid=1790763&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F681397 Vertically stacked InAs/InP columnar quantum dots (CQDs) for polarization insensitive semiconductor amplifier in telecommunications applications are studied theoretically. An axial model is used to predict mechanical, electronic, and optical properties of these CQDs. A crossover from a dominant transverse electric (TE) optical ground state absorption to a dominant transverse magnetic (TM) absorption is predicted for a number of layers equal to about 9 in good agreement with the experiment. The weight of the light hole component of the valence band ground state increases as a function of the number of layers. The change of the TE/TM polarization ratio is also associated to a symmetry change of the heavy hole component. A modification of the aspect ratio of the CQD seems to be the most impor... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1790763 Sun, 14 Sep 2008 14:21:24 +0100 1790763 http://www.medworm.com/index.php?rid=1705370&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F249402 Samples of general formula 4AgI-(1-x)PbI2-2xCuI, x=0–0.4, have been prepared and investigated by XRD, DSC, and temperature-dependent conductivity studies. X-ray diffractograms showed the presence of binary system consisting of AgI and PbI2 in the sample x=0. Cu-substituted samples showed very similar diffractograms to that of the pure compound which indicates that no effect for the substitution on the nature of the binary system. DSC curves showed the presence of phase transition whose temperature increased with Cu+ ratio in the system. Ionic conductivity measurements confirmed the occurrence of the phase transition and showed that the high temperature phase is superionic conducting, whose conductivity increases with the increasing Cu+ amount in the system. (Source: Research Letter... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1705370 Thu, 14 Aug 2008 18:29:54 +0100 1705370 http://www.medworm.com/index.php?rid=1696994&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F749305 Specific features of the charge-transfer (CT) states and O2p→Cr3d transitions in the octahedral (CrO6)9− complex are considered in the cluster approach. The reduced matrix elements of the electric-dipole transition operator are calculated on many-electron wave functions of the complex corresponding to the initial and final states of a CT transition. Modeling the optic spectrum of chromites has yielded a complicated CT band. The model spectrum is in satisfactory agreement with experimental data which demonstrates the limited validity of the generally accepted concept of a simple structure of CT spectra. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1696994 Tue, 12 Aug 2008 13:52:58 +0100 1696994 http://www.medworm.com/index.php?rid=1677640&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F237023 Formation of nanocrystalline rare earth was prepared by solgel route, using tetra-ethoxysilane and Nd (NO3)3 as precursor materials and HCl as a catalyst. The prepared samples were submitted to thermal treatments at temperature 500∘C (5 hours) and 800∘C (10 hours). Structural changes were investigated by XRD, FTIR spectroscopy, and SEM. At 800∘C (10 hours) resulted in the formation of cubic Nd2O3 nanocrystallites with average size ∼ 20 nm. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1677640 Mon, 04 Aug 2008 15:09:47 +0100 1677640 http://www.medworm.com/index.php?rid=1669077&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F717414 Thin disk laser is analyzed, assuming that the heat is drained in the same direction, as the optical pulse, withdrawing the stored energy, comes. Amplified spontaneous emission, the background loss, and overheating are taken into account with simple model. The scaling laws of the basic parameters are deduced. For the case of fixed repetition rate, the upper bound of thickness is obtained. Key parameters are suggested. The key energy parameter is promoted as criterion for evaluation of different laser materials for the high energy, high mean power disk lasers. The maximum energy per active element is estimated. For the scaling up the power and/or energy withdrawn from a single active element, the background loss should scale down inversely proportional to the cube of the background loss. Th... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1669077 Thu, 31 Jul 2008 16:32:04 +0100 1669077 http://www.medworm.com/index.php?rid=1639585&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F434936 Light emitting diodes made out of inverse spin valves of a ferromagnetic half metal sandwiched between two nonmagnetic metals are proposed. Based on a giant spin-dependent chemical potential difference created under an external bias, the inverse spin valves are possible to emit light when electrons with the higher chemical potential flip their spins and become the electrons of the opposite spin with the lower chemical potential. The frequency of this type of light emitting diodes is tunable by the bias. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1639585 Sun, 20 Jul 2008 15:49:28 +0100 1639585 http://www.medworm.com/index.php?rid=1618355&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F589269 We introduce a class of potentials for which the time-dependent Schrödinger equation with position-dependent (effective) mass allows reduction to a stationary Schrödinger equation. This reduction is done by a particular point canonical transformation which preserves L2-normalizability. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618355 Mon, 14 Jul 2008 14:02:50 +0100 1618355 http://www.medworm.com/index.php?rid=1618354&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F890916 We construct a dyon solution for the noncommutative version of the Yang-Mills-Higgs model with a ϑ-term. Extending the Noether method to the case of a noncommutative gauge theory, we analyze the effect of CP violation induced both by the ϑ-term and by noncommutativity proving that the Witten effect formula for the dyon charge remains the same as in ordinary space. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618354 Mon, 14 Jul 2008 14:02:50 +0100 1618354 http://www.medworm.com/index.php?rid=1618353&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F879017 Using hybrid density functional theory and a relatively large basis set, the lowest energy equilibrium structure, vibrational spectrum, and natural orbital analysis were obtained for magnesium diboride clusters [(MgB2)x for x=1,2, and 3]. For comparison, boron clusters [Bx for x=2,4, and 6] were also considered. The MgB2 and (MgB2)2 showed equilibrium structures with the boron atoms in arrangements similar to what was obtained for pure boron atoms, whereas, for (MgB2)3 a different arrangement of boron was obtained. From the population analysis, large electron density in the boron atoms forming the clusters was observed. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618353 Mon, 14 Jul 2008 14:02:50 +0100 1618353 http://www.medworm.com/index.php?rid=1618352&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F746892 Computer simulations of the radiation defects created in beryllium irradiated by fast neutrons (E>0.1 MeV) using the Geant4 and SRIM packages were carried out. The atom cascade displacements in Be at a neutron fluence of 1.6×1020 n/cm2 were determined to be 0.06 dpa and the helium concentration was calculated to be 168 appm. The concentration of L6i has been estimated to be 5% in comparison to the He concentration. Nanoscale calculations were done in 30×30×30 nm cube of fast neutron-irradiated Be. A correlation between the Be primary knock-on atom (PKA) energies and the damage cascades has been established. The final defect distributions of single vacancies, divacancies, and small vacancy clusters were examined. Our result... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618352 Mon, 14 Jul 2008 14:02:50 +0100 1618352 http://www.medworm.com/index.php?rid=1618351&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F286546 With the continued scaling of the SiO2 thickness below 2 nm in CMOS devices, a large direct-tunnelling current flow between the gate electrode and silicon substrate is greatly impacting device performance. Therefore, higher dielectric constant materials are desirable for reducing the gate leakage while maintaining transistor performance for very thin dielectric layers. Despite its not very high dielectric constant (∼10), Al2O3 has emerged as one of the most promising high-k candidates in terms of its chemical and thermal stability as its high-barrier offset. In this paper, a theoretical study of the physical and electrical properties of Al2O3 gate dielectric is reported including I(V) and C(V) characteristics. By using a stack of Al2O3/SiO2 with an appropriate equivalent oxid... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618351 Mon, 14 Jul 2008 14:02:50 +0100 1618351 http://www.medworm.com/index.php?rid=1618350&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F148505 A type of nanopinhole-based plasmonic structure is presented. It can realize superfocusing within micron-scale propagation distance with spatial resolution beyond diffraction limit. Cut-off wavelength effect is highlighted for understanding how periodicity distribution of the nanopinholes influences transmission and focusing through the structure. Redshift peak transmission occurs while the periodicity increases. In addition, focusing property of the plasmonic structures is analyzed for the monochromatic illumination with different incident wavelengths ranging from 400 nm to 750 nm. The easy fabrication and high focusing performance of the proposed structures may be used in data storage devices, bioimaging, and nanolithography. (Source: Research Letters in Physics... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618350 Mon, 14 Jul 2008 14:02:50 +0100 1618350 http://www.medworm.com/index.php?rid=1618349&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F135289 Many heat and mass transport problems involve particle-fluid systems, where the assumption of Stokes flow provides a very good approximation for representing small particles embedded within a viscous, incompressible fluid characterizing the steady, creeping flow. The present work is concerned with some interesting practical aspects of the theoretical analysis of Stokes flow in spheroidal domains. The stream function ψ, for axisymmetric Stokes flow, satisfies the well-known equation E4ψ=0. Despite the fact that in spherical coordinates this equation admits separable solutions, this property is not preserved when one seeks solutions in the spheroidal geometry. Nevertheless, defining some kind of semiseparability, the complete solution for ψ in spheroidal coordinates ha... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618349 Mon, 14 Jul 2008 14:02:50 +0100 1618349 http://www.medworm.com/index.php?rid=1618348&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F592869 Contradictory to the widespread perception, storage ring free-electron lasers with substantial net gain can generate peak lasing power reaching GW levels in the so-called superpulse mode. This power level is sufficient for studies of nonlinear processes and efficient intracavity harmonic generation. This letter describes the physics of the superpulses and a phase-space refreshment in the electron beam responsible for this phenomenon. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618348 Mon, 14 Jul 2008 14:02:50 +0100 1618348 http://www.medworm.com/index.php?rid=1618347&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F293517 The structural, elastic, and electronic properties of the hard material ReB2 have been investigated by means of density functional theory. The calculated equilibrium structural parameters of ReB2 are in agreement with the experimental results. Our result of bulk modulus shows that it is a low compressible material. Furthermore, the elastic anisotropy is discussed by investigating the elastic stiffness constants. The charge density and the electronic properties indicate that the covalent bonding of Re-B and B-B plays an important role in formation of a hard material. The good metallicity and hardness of ReB2 might serve as hard conductors. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618347 Mon, 14 Jul 2008 14:02:50 +0100 1618347 http://www.medworm.com/index.php?rid=1618346&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F570167 As it is well known, a quantum system depending on parameters exhibits the (geometric) Berry phase when parameters are varying in the adiabatic limit. A generalization of the Berry phase is given in the present paper for a nonadiabatic change of parameters, which leads to quantum transitions in the system. This generalization is applied to noninertial motions and it is shown that such motions may induce quantum transitions for a system in an external field governed by Schrodinger's equation. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618346 Mon, 14 Jul 2008 14:02:50 +0100 1618346 http://www.medworm.com/index.php?rid=1618345&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F837503 We report on the observation of quantum confinement effects and the influence of surface-related states due to the formation of nanograins on ultrashort relaxation near the direct critical points of silicon nanofilms following UV-excitation. Direct photoexcitation of the samples in the vicinity of the Γ critical points of the first Brillouin zone has been achieved using femtosecond pulses in the spectra range of 290–400 nm. Transient absorption measurements show a substantial enhancement of state filling with decreasing the film thickness down to 5 nm due to quantum confinement in the z-direction. Furthermore, the state filling of surface-related states of nanograins suggests that t... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618345 Mon, 14 Jul 2008 14:02:50 +0100 1618345 http://www.medworm.com/index.php?rid=1618344&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F157070 Calculation of magnetization of the ternary single crystal compound NdRh2Ge2 has been carried out by using the wave-like molecular field model to explain the complex magnetic behavior. The field-induced magnetic structures having the propagation vectors, Q2=(0,0,39/40), Q3=(0,0,35/40), Q4=(0,0,31/40), and Q5=(0,0,0/40) (= the field-induced ferromagnetic phase) were proposed. Calculation on the basis of these structures and the antiferromagnetic phase with Q1=(0,0,1) well reproduces the experimental magnetization processes and H-T magnetic phase diagram. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618344 Mon, 14 Jul 2008 14:02:50 +0100 1618344 http://www.medworm.com/index.php?rid=1618343&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F891324 Using a localized laser-heating method to allow the use of system size as a control parameter, we experimentally investigate, using liquid-crystal electroconvection with soft boundary conditions, the onset of spatial temporal chaos (STC) with increasing system size. We find that temporal periodicity is significantly quenched as the system size increases. The increase of the fourth moment (kurtosis) of the temporal Fourier transform provides a very useful quantitative measure of the loss of temporal periodicity (hence the onset of STC) as the pattern size increases, and also provides a simple means for determining a natural chaotic length scale. This length scale is comparable to the length of vertical rows observed in the original pattern. Our experiments, thus, imply that there are well-d... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618343 Mon, 14 Jul 2008 14:02:50 +0100 1618343 http://www.medworm.com/index.php?rid=1618342&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F786939 We performed numerical studies of differential gain in a coupled quantum well structures built from InGaAsN. Differential gain in In0.38Ga0.62As1_yNy/GaAs quantum well structures was determined and analyzed. A 10-band k_p Hamiltonian matrix was used in the calculations and solved self-consistently with Poisson's equation. The effect of Nitrogen composition and barrier thickness on differential gain has been determined. The influence of Nitrogen composition on differential gain is significant whereas barrier effects are modest. (Source: Research Letters in Physics) Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618342 Mon, 14 Jul 2008 14:02:50 +0100 1618342 http://www.medworm.com/index.php?rid=1618341&cid=s_37720_75_f&fid=37720&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F168231 This letter focuses on studying a new energy-work relationship numerical integration scheme of nonconservative Hamiltonian systems. The signal-stage, multistage, and parallel composition numerical integration schemes are presented for this system. The high-order energy-work relation scheme of the system is constructed by a parallel connection of n multistage scheme of order 2 which its order of accuracy is 2n. The connection, which is discrete analog of usual case, between the change of energy and work of nonconservative force is obtained for nonconservative Hamiltonian systems.This letter also shows that the more the stages of the schemes are, the less the error rate of the scheme is for nonconservative Hamiltonian systems. Finally, an applied example is discussed to illustrate these resu... Research Letters in Physics journals http://www.medworm.com/rss/comments.php?id=1618341 Mon, 14 Jul 2008 14:02:50 +0100 1618341