bluuebunny/crossref_metadata_2025 huggingface dataset:
Equivalence classes and canonical forms for two-qutrit entangled states of rank four having positive partial transpose
Authors: Chen Lin , Đoković Dragomir Ž.
Published: October 2012

Let \documentclass[12pt]{minimal}\begin{document}${\cal E}^{\prime }$\end{document}E′ denote the set of non-normalized two-qutrit entangled states of rank four having positive partial transpose (PPT). We show that the set of stochastic local operations and classical communications (SLOCC) equivalence classes of states in \documentclass[12pt]{minimal}\begin{document}${\cal E}^{\prime }$\end{document}E′, equipped with the quotient topology, is homeomorphic to the quotient R/A5 of the open rectangular box R⊂ R4 by an action of the alternating group A5. We construct an explicit map \documentclass[12pt]{minimal}\begin{document}$\omega :\Omega \rightarrow {\cal E}^{\prime }$\end{document}ω:Ω→E′, where Ω is the open positive orthant in  R4, whose image ω(Ω) meets every SLOCC equivalence class \documentclass[12pt]{minimal}\begin{document}$E\subseteq {\cal E}^{\prime }$\end{document}E⊆E′. Although the intersection ω(Ω) ∩ E is not necessarily a singleton set, it is always a finite set of cardinality at most 60. By abuse of language, we say that any state in ω(Ω) ∩ E is a canonical form of any ρ ∈ E. In particular, we show that all checkerboard PPT entangled states can be parametrized up to SLOCC equivalence by only two real parameters. We also summarize the known results on two-qutrit extreme PPT states and edge states, and examine which other interesting properties they may have. Thus we find the first examples of extreme PPT states whose rank is different from the rank of its partial transpose.
Zero and finite temperature Casimir effect of massive vector field between real metals
Authors: Teo L. P.
Published: October 2012

We consider the Casimir effect of a massive vector field between two semi-infinite dielectric slabs. We first derive the generalization of the Lifshitz formula that gives the Casimir interaction energy of two magnetodielectric slabs separated by a magnetodielectric medium due to the vacuum fluctuations of a massive vector field. We then discuss the asymptotic behaviors of the Casimir energy and the Casimir force in various limits, such as low temperature, high temperature, small mass, large mass, up to the first order in the finite conductivity correction, for two real metal semispaces whose dielectric property is described by the plasma model. Application to the Casimir effect in Randall-Sundrum spacetime is briefly discussed.
Some Hamiltonian models of friction II
Authors: Egli Daniel , Gang Zhou
Published: October 2012

In the present paper we consider the motion of a very heavy tracer particle in a medium of a very dense, non-interacting Bose gas. We prove that, in a certain mean-field limit, the tracer particle will be decelerated and come to rest somewhere in the medium. Friction is caused by emission of Cerenkov radiation of gapless modes into the gas. Mathematically, a system of semilinear integro-differential equations, introduced in Fröhlich et al. [“Some hamiltonian models of friction,” J. Math. Phys. 52(8), 083508 (2011)10.1063/1.3619799], describing a tracer particle in a dispersive medium is investigated, and decay properties of the solution are proven. This work is an extension of Fröhlich et al. [“Friction in a model of hamiltonian dynamics,” Commun. Math. Phys. 315(2), 401–444 (2012)10.1007/s00220-012-1564-2]; it is an extension because no weak coupling limit for the interaction between tracer particle and medium is assumed. The technical methods used are dispersive estimates and a contraction principle.
The granular silo as a continuum plastic flow: The hour-glass vs the clepsydra
Authors: Staron L. , Lagrée P.-Y. , Popinet S.
Published: October 2012

The granular silo is one of the many interesting illustrations of the thixotropic property of granular matter: a rapid flow develops at the outlet, propagating upwards through a dense shear flow while material at the bottom corners of the container remains static. For large enough outlets, the discharge flow is continuous; however, by contrast with the clepsydra for which the flow velocity depends on the height of fluid left in the container, the discharge rate of granular silos is constant. Implementing a plastic rheology in a 2D Navier-Stokes solver (following the μ(I)-rheology or a constant friction), we simulate the continuum counterpart of the granular silo. Doing so, we obtain a constant flow rate during the discharge and recover the Beverloo scaling independently of the initial filling height of the silo. We show that lowering the value of the coefficient of friction leads to a transition toward a different behavior, similar to that of a viscous fluid, and where the filling height becomes active in the discharge process. The pressure field shows that large enough values of the coefficient of friction (≃0.3) allow for a low-pressure cavity to form above the outlet, and can thus explain the Beverloo scaling. In conclusion, the difference between the discharge of a hourglass and a clepsydra seems to reside in the existence or not of a plastic yield stress.
An alternative approach to efficient simulation of micro/nanoscale phonon transport
Authors: Péraud Jean-Philippe M. , Hadjiconstantinou Nicolas G.
Published: October 2012

Starting from the recently proposed energy-based deviational formulation for solving the Boltzmann equation [J.-P. Péraud and N. G. Hadjiconstantinou, Phys. Rev. B 84, 205331 (2011)], which provides significant computational speedup compared to standard Monte Carlo methods for small deviations from equilibrium, we show that additional computational benefits are possible in the limit that the governing equation can be linearized. The proposed method exploits the observation that under linearized conditions (small temperature differences) the trajectories of individual deviational particles can be decoupled and thus simulated independently; this leads to a particularly simple and efficient algorithm for simulating steady and transient problems in arbitrary three-dimensional geometries, without introducing any additional approximation.
High-temperature thermoelectric properties of the double-perovskite ruthenium oxide (Sr1−xLax)2ErRuO6
Authors: Takahashi Ryohei , Okazaki Ryuji , Yasui Yukio , Terasaki Ichiro , Sudayama Takaaki , Nakao Hironori , Yamasaki Yuichi , Okamoto Jun , Murakami Youichi , Kitajima Yoshinori
Published: October 2012

We have prepared polycrystalline samples of (Sr1−xLax)2ErRuO6 and (Sr1−xLax)2YRuO6, and have measured the resistivity, Seebeck coefficient, thermal conductivity, susceptibility, and x-ray absorption in order to evaluate the electronic states and thermoelectric properties of the doped double-perovskite ruthenates. We have observed a large Seebeck coefficient of −160 μV/K and a low thermal conductivity of 7 mW/cmK for x = 0.1 at 800 K in air. These two values are suitable for efficient oxide thermoelectrics, although the resistivity is still as high as 1 Ω  cm. From the susceptibility and x-ray absorption measurements, we find that the doped electrons exist as Ru4+ in the low spin state. On the basis of the measured results, the electronic states and the conduction mechanism are discussed.
Analysis of laminar jet impingement and hydraulic jump on a horizontal surface with slip
Authors: Prince Joseph F. , Maynes Daniel , Crockett Julie
Published: October 2012

This paper explores the influence surface slip, uniform in all directions with constant slip length, exerts on the physics of laminar jet impingement on a flat horizontal surface. Slip exists on superhydrophobic surfaces, and due to the relatively thin film dynamics associated with the growth of the laminar jet after impingement, its influence on the fluid physics is significant. An analysis based on momentum considerations is presented that allows prediction of the relevant thin film parameters as a function of radial position from the impingement point, jet Reynolds number, and constant relative slip length of the surface. Further, the analysis allows determination of the hydraulic jump location in terms of laminar jet characteristics and imposed downstream liquid depth. The results reveal that at a given radial location, the boundary layer growth and thin film thickness decrease, while the surface velocity of the thin film increases with increasing slip at the surface. The departure from classical no-slip behavior is quantified over a range of realizable slip conditions. Increasing slip length also leads to formation of hydraulic jumps at increasing radial location. An expression based on the results is presented that allows prediction of the hydraulic jump location as a function of the magnitude of the slip and all other influencing variables.
An innovative cloak enables arbitrary multi-objects hidden with visions and movements
Authors: Huang Tsung-Yu , Lee Hsin-Cheng , Un Ieng-Wai , Yen Ta-Jen
Published: October 2012

We propose an innovative cloak to enable arbitrary multi-objects hidden with visions and movements. We develop the cloak with spatially varying constitutive parameters by employing transformation optics with two-step coordinate transformations and testify the performance of the cloak by finite element based simulation software. In simulation, the electric field distributions (Ez) of the cloak for different circumstances agree with the analytical prediction well.
Giant magnetoresistance effect in graphene with asymmetrical magnetic superlattices
Authors: Huo Q. H. , Wang R. Z. , Yan H.
Published: October 2012

We investigate a giant magnetoresistance (MR) effect in periodic, asymmetric magnetic superlattices (MSLs) on graphene. The MR ratio shows a strong dependence on both the interval of magnetic barriers and the asymmetry degree of the structures. With the increase of the number of periods, there is only one MR peak and the drift of the position of the peak appears around a specific Fermi energy. The highest value of the maximal MR ratio can be up to 1017%. Our studies indicate that the graphene-based asymmetric MSLs structure is an ideal candidate of a giant MR device, e.g., the magnetic reading device.
Vanadium bound exciton luminescence in 6H-SiC
Authors: Wang S. C. , Wang G. , Liu Y. , Jiang L. B. , Wang W. J. , Chen X. L.
Published: October 2012

The source responsible for V2 (1.398 eV) luminescence in 6H-SiC is recognized as a favorable defect for quantum information processing. However, the origin of V2 luminescence is still controversial. With careful photoluminescence measurements, it is found that V2 line shows clear bound exciton luminescence features. Furthermore, a mechanism based on neutral vanadium donor bound exciton is put forward to explain the origin of V2 luminescence. The results may provide some insights to understanding the nature of the promising qubit candidates in SiC.
Vibrational modes of methane in the structure H clathrate hydrate from ab initio molecular dynamics simulation
Authors: Hiratsuka Masaki , Ohmura Ryo , Sum Amadeu K. , Yasuoka Kenji
Published: October 2012

Vibrational spectra of guest molecules in clathrate hydrates are frequently measured to determine the characteristic signatures of the molecular environment and dynamical properties of guest-host interactions. Here, we present results of our study on the vibrational frequencies of methane molecules in structure H clathrate hydrates, namely, in the 512 and 435663 cages, as the frequencies of stretching vibrational modes in these environments are still unclear. The vibrational spectra of methane molecules in structure H clathrate hydrate were obtained from ab initio molecular dynamics simulation and computed from Fourier transform of autocorrelation functions for each distinct vibrational mode. The calculated symmetric and asymmetric stretching vibrational frequencies of methane molecules were found to be lower in the 435663 cages than in the 512 cages (3.8 cm−1 for symmetric stretching and 6.0 cm−1 for asymmetric stretching). The C–H bond length and average distance between methane molecules and host-water molecules in 435663 cages were slightly longer than those in the 512 cages.
Synthesis and efficient near-infrared quantum cutting of Pr3+/Yb3+ co-doped LiYF4 single crystals
Authors: Hu Jianxu , Xia Haiping , Hu Haoyang , Zhang Yuepin , Jiang Haochuan , Chen Baojiu
Published: October 2012

Yttrium lithium fluoride single crystals doped with trivalent lanthanide ions Pr3+ and Yb3+ are prepared by an improved Bridgman method. X-ray diffraction, photoluminescence excitation, and emission spectra and decay curves are measured to investigate the structural and luminescent properties of the crystals. An efficient near-infrared quantum cutting downconversion from the crystals was observed. The downconversion involves the emission of two near-infrared photons for each blue photon absorbed at 480 nm via cross relaxation energy transfer from Pr3+ to Yb3+. Decay curve fitting using a modified Inokuti-Hirayama expression indicates dipole-dipole energy transfer from Pr3+ to Yb3+, which is consistent with the expected cross-relaxation scheme. The maximum quantum cutting efficiency approaches up to 168.4% in LiYF4: 0.28 mol. % Pr3+ and 6.02 mol. % Yb3+, and this is equivalent to 68.4% energy transfer efficiency.
Omnidirectionally continuous liquid crystal domain structure for high transmittance vertically aligned nematic mode
Authors: Choi Yoonseuk , Soo Park Min , Hyuk Kwon Jin , Seog Gwag Jin
Published: October 2012

A vertically aligned (VA) nematic liquid crystal (LC) mode with field-driven continuous domain is demonstrated using a transparent electrode deposited-microlens structure with a matching planarization layer. Due to curved electrodes, an axially symmetric omnidirectional domain of liquid crystal can easily be obtained on the flat surface of the planarization layer, with a defect-free symmetric domain of LCs. A significant increase in the transmittance can be obtained using this mode, in comparison to conventional VA modes.
Communication: An obligatory glass surface
Authors: Ashtekar S. , Nguyen D. , Zhao K. , Lyding J. , Wang W. H. , Gruebele M.
Published: October 2012

Theory predicts, and experiments have shown, that dynamics is faster at glass surfaces than in the bulk, allowing the glass to settle into deeper energy landscape minima, or “age more.” Is it possible that a glass surface could survive at temperatures where the bulk crystallizes, or that it could remain glassy after the bulk is heated all the way to its melting temperature and re-cooled? We image in real-time and with sub-nanometer resolution the two-state surface dynamics on a cerium-based glass surface, from deep within the glassy regime to above the crystallization temperature. Unlike other surfaces that we have studied, this glass surface remains amorphous even after the bulk re-crystallizes. The surface retains non-crystalline structure and two state dynamics of cooperatively rearranging regions even after heat annealing to just below the bulk melting temperature. The heat-annealed cooperatively rearranging regions are larger than originally, a sign that the surface is well aged. The surface dynamics depends weakly on temperature, showing no sign of the superexponential increase in bulk dynamics expected near Tg.
Characterization and simulation of the first extensional mode of rectangular micro-plates in liquid media
Authors: Manzaneque T. , Ruiz V. , Hernando-García J. , Ababneh A. , Seidel H. , Sánchez-Rojas J. L.
Published: October 2012

This Letter reports on the characterization of the first extensional mode of AlN-actuated mid-point supported resonant microplates in liquid media. Devices of different dimensions were fabricated and both optical and electrical measurements were performed in order to identify the modal shape under study and determine its quality factor. The dependence of the quality factor on the plate dimensions is discussed based on analytical and finite element simulation results. A quality factor of 100 was achieved in water at 3.8 MHz, and the suitability of this kind of device to work under high viscous condition (up to 51 cP) was demonstrated.
Quantum oscillations from a two-dimensional electron gas at a Mott/band insulator interface
Authors: Moetakef Pouya , Ouellette Daniel G. , Williams James R. , James Allen S. , Balents Leon , Goldhaber-Gordon David , Stemmer Susanne
Published: October 2012

We report on the magnetotransport properties of a prototype Mott insulator/band insulator perovskite heterojunction in magnetic fields up to 31 T and at temperatures between 360 mK and 10 K. Shubnikov-de Haas oscillations in the magnetoresistance are observed. The oscillations are two-dimensional in nature and are interpreted as arising from either a single, spin-split subband or two subbands. In either case, the electron system that gives rise to the oscillations represents only a fraction of the electrons in the space charge layer at the interface. The temperature dependence of the oscillations is used to extract an effective mass of ∼1 me for the subband(s). The results are discussed in the context of the t2g-states that form the bottom of the conduction band of SrTiO3.
Terahertz beam focusing based on plasmonic waveguide scattering
Authors: Monnai Yasuaki , Altmann Kristian , Jansen Christian , Koch Martin , Hillmer Hartmut , Shinoda Hiroyuki
Published: October 2012

We demonstrate free-space focusing of terahertz (THz) radiation by scattering plasmonic surface-waves into the air. We use a grating of shallow holes which contains non-equidistant defects which act as scattering centers. The scattering occurs with defined phase delays such that the waves emitted in free-space interfere constructively to form a focus above the waveguide surface. In contrast to conventional lenses, this structure does not require any free-space on its backside and has great potential for integrated THz optics.
Significant enhancement in energy density of polymer composites induced by dopamine-modified Ba0.6Sr0.4TiO3 nanofibers
Authors: Song Yu , Shen Yang , Hu Penghao , Lin Yuanhua , Li Ming , Nan C. W.
Published: October 2012

Ba0.6Sr0.4TiO3 (BST) nanofibers prepared via electrospinning and modified by dopamine are used as dielectric fillers in polyvinylidene fluoride (PVDF)-based composites. With 4.4 vol. % of BST nanofibers, the extractable energy density of the BST/PVDF composites is more than doubled as compared with pure PVDF matrix. Such significant enhancement is attributed to the combined effect of both surface modification by dopamine and large aspect ratio of the BST nanofibers. Paraelectric or anti-ferroelectric fillers of large aspect ratio may serve as a general strategy for enhanced electric energy density in polymer composites.
Resonant plasmonic effects in periodic graphene antidot arrays
Authors: Nikitin A. Yu. , Guinea F. , Martin-Moreno L.
Published: October 2012

We show that a graphene sheet perforated with micro- or nano-size antidots has prominent absorption resonances in the microwave and terahertz regions. These resonances correspond to surface plasmons of a continuous sheet “perturbed” by a lattice. They are excited in different diffraction orders, in contrast to cavity surface plasmon modes existing in disconnected graphene structures. The resonant absorption by the antidot array can essentially exceed the absorption by a continuous graphene sheet, even for high antidot diameter-to-period aspect ratios. Surface plasmon-enhanced absorption and suppressed transmission are more efficient for higher relaxation times of the charge carriers.
Dynamic medium containing growth differentiation factor-9 and FSH maintains survival and promotes in vitro growth of caprine preantral follicles after long-term in vitro culture
Authors: Alves A. M. C. V. , Chaves R. N. , Rocha R. M. P. , Lima L. F. , Andrade P. M. , Lopes C. A. P. , Souza C. E. A. , Moura A. A. A. , Campello C. C. , Báo S. N. , Smitz J. , Figueiredo J. R.
Published: October 2012

The aim of the present study was to evaluate the effects of growth differentiation factor 9 (GDF-9) and FSH on the in vitro development of caprine preantral follicles cultured for 16 days. Ovarian fragments were cultured in αMEM+ (α-minimum essential medium, pH 7.2–7.4, 10 μg mL–1 insulin, 5.5 μg mL–1 transferrin, 5.0 ng mL–1 selenium, 2 mM glutamine, 2 mM hypoxanthine and 1.25 mg mL–1 bovine serum albumin) in the absence or presence of 200 ng mL–1 GDF-9 and/or 50 ng mL–1 FSH added during the first (Days 0–8) and/or second (Days 8–16) half of the culture period. Non-cultured and cultured fragments were processed for histological and ultrastructural analyses. After 16 days, all treatments using GDF-9 or FSH showed higher rates of follicular survival compared with αMEM+ alone. Compared with non-cultured control, sequential culture media containing GDF-9 and/or FSH significantly increased the percentage of developing follicles and follicle diameter. Moreover, a progressive increase in oocyte diameter was observed only with sequential culture medium containing GDF-9 until Day 8 followed by FSH (GDF-9/FSH) in the second half of the culture period. After 16 days of culture, ultrastructural analysis confirmed the integrity of follicles cultured in the presence of GDF-9/FSH. In conclusion, a dynamic medium containing GDF-9 and FSH (GDF-9/FSH) maintained follicular integrity and promoted activation of primordial follicles and growth during long-term in vitro culture of goat preantral follicles.
Characterising fire regimes in Spain from fire statistics
Authors: Moreno M. Vanesa , Chuvieco Emilio
Published: October 2012

The concept of fire regime refers to a variety of fire characteristics occurring at a given place and period of time. Understanding fire regimes is relevant to fire ecology and fire management because it provides a better understanding of effects of fire as well as the potential effects of different future scenarios. Recent changes in the traditional fire regimes linked to climate and socioeconomic transformations in European Mediterranean areas have influenced fire regimes and their effects on both ecosystems and people. This paper presents a methodology for characterising fire regimes based on historical fire statistics. The analysis includes three dimensions: density, seasonality and interannual variability. The raw records were pre-processed to eliminate errors, and a principal component analysis was performed to identify the primary factors involved in the variation. A cluster analysis was then used to define the fire regimes. Approximately 38% of the spatial cells examined were found to have significant fire activity, but in spite that fires are important in these areas, fire activity showed a high interannual variability. Four fire regimes in the Spanish peninsular territory were described in terms of the density and seasonality of fire activity.
Activity-dependent retrograde laminin A signaling regulates synapse growth at
Drosophila
neuromuscular junctions
Authors: Tsai Pei-I , Wang Manyu , Kao Hsiu-Hua , Cheng Ying-Ju , Lin Yu-Jing , Chen Ruey-Hwa , Chien Cheng-Ting
Published: October 2012

Retrograde signals induced by synaptic activities are derived from postsynaptic cells to potentiate presynaptic properties, such as cytoskeletal dynamics, gene expression, and synaptic growth. However, it is not known whether activity-dependent retrograde signals can also depotentiate synaptic properties. Here we report that laminin A (LanA) functions as a retrograde signal to suppress synapse growth at
Drosophila
neuromuscular junctions (NMJs). The presynaptic integrin pathway consists of the integrin subunit βν and focal adhesion kinase 56 (Fak56), both of which are required to suppress crawling activity-dependent NMJ growth. LanA protein is localized in the synaptic cleft and only muscle-derived LanA is functional in modulating NMJ growth. The LanA level at NMJs is inversely correlated with NMJ size and regulated by larval crawling activity, synapse excitability, postsynaptic response, and anterograde Wnt/Wingless signaling, all of which modulate NMJ growth through LanA and βν. Our data indicate that synaptic activities down-regulate levels of the retrograde signal LanA to promote NMJ growth.
Basic leucine zipper transcription factor Hac1 binds DNA in two distinct modes as revealed by microfluidic analyses
Authors: Fordyce Polly M. , Pincus David , Kimmig Philipp , Nelson Christopher S. , El-Samad Hana , Walter Peter , DeRisi Joseph L.
Published: October 2012

A quantitative understanding of how transcription factors interact with genomic target sites is crucial for reconstructing transcriptional networks in vivo. Here, we use Hac1, a well-characterized basic leucine zipper (bZIP) transcription factor involved in the unfolded protein response (UPR) as a model to investigate interactions between bZIP transcription factors and their target sites. During the UPR, the accumulation of unfolded proteins leads to unconventional splicing and subsequent translation of
HAC1
mRNA, followed by transcription of UPR target genes. Initial candidate-based approaches identified a canonical
cis
-acting unfolded protein response element (UPRE-1) within target gene promoters; however, subsequent studies identified a large set of Hac1 target genes lacking this UPRE-1 and containing a different motif (UPRE-2). Using a combination of unbiased and directed microfluidic DNA binding assays, we established that Hac1 binds in two distinct modes: (
i
) to short (6–7 bp) UPRE-2-like motifs and (
ii
) to significantly longer (11–13 bp) extended UPRE-1-like motifs. Using a genetic screen, we demonstrate that a region of extended homology N-terminal to the basic DNA binding domain is required for this dual site recognition. These results establish Hac1 as the first bZIP transcription factor known to adopt more than one binding mode and unify previously conflicting and discrepant observations of Hac1 function into a cohesive model of UPR target gene activation. Our results also suggest that even structurally simple transcription factors can recognize multiple divergent target sites of very different lengths, potentially enriching their downstream target repertoire.
Optical Kerr constant of liquid crystals with gold-nanoparticle-doped alignment films
Authors: Fuh Andy Ying-Guey , Lin Ci-Yong , Li Ming-Shian , Lin Hui-Chi
Published: October 2012

This investigation studies the optical Kerr constant (n
2) of liquid crystals with cell substrates being treated with gold-nanoparticle-doped alignment films using the Z-scan technique. The results indicate that the doping of gold nanoparticles into polyvinyl-alcohol alignment films in a liquid crystal cell enhances the optical Kerr constant, n
2, of the liquid crystals. This enhancement is caused by the thermal effect of the absorption of light due to the localized surface plasmon resonance of gold nanoparticles. The magnitude and the sign of n
2 of a sample can be modulated by a combination of the applied external electric and optical fields. Furthermore, the variation of n
2 of the sample with ambient temperature is studied.
Studies on the fabrication of self-ordered titania nanohole arrays on Si substrates
Authors: Venkatachalam S , Hayashi H , Ebina T , Nanjo H
Published: October 2012

Titanium (Ti) thin films were deposited with and without ion bombardment on Si substrates by ion-beam sputter deposition method. Ti thin films deposited with ion bombardment were under compressive strain. The strain in the films deposited without ion bombardment changed from compressive to tensile as the film thickness was increased from 220 to 450 nm. TiO2 nanohole arrays were prepared by electrochemical anodization method. It was observed that the electrolyte temperature and strain in the films strongly influenced the formation of nanohole arrays of the TiO2 films. Amorphous TiO2 was changed into rutile TiO2 after annealing at 450 °C for an hour. The I–V characteristic of the Au/TiO2/Si device showed the Schottky behaviour.
A study on the formation of Ag nanoparticles on the surface and catcher by ion beam irradiation of Ag thin films
Authors: Singh Udai B , Agarwal Dinesh C , Khan Saif A , Mohapatra Satyabrata , Tripathi Ambuj , Avasthi Devesh K
Published: October 2012

Irradiation of Ag thin films with 100 MeV Ag ions leads to the formation of Ag nanoparticles on the surface as well as on the catcher, due to electronic energy loss mediated sputtering of Ag. The experimentally determined sputter yield of Ag is found to be three orders of magnitude higher than the values expected for bulk Ag, which is explained on the basis of the inelastic thermal spike model. The confinement of energy in the nanoparticles having size smaller than the electron mean free path (λ) and higher surface coverage area results in a higher sputtering yield. Transmission electron microscopy was performed to study the size distribution of nanoparticles on the catcher. The variation of sputtered particle yield with the number of constituent atoms follows an inverse power law with the value of exponent (δ) ∼ 0.33, at a fluence of 1 × 1013 ions cm−2. With increase in fluence up to 1 × 1014 ions cm−2, an additional value of exponent of δ ≈ 1 arises. The size of Ag nanoparticles is decreased with increased fluence due to ion-induced sputtering. The irradiated sample is found to have partially embedded nanoparticles showing localized surface plasmon resonance.
Effect of Ge substitution on carrier mobilities and thermoelectric properties of sintered p-type Ba8Ga16+xSn30−x−yGey with the type-VIII clathrate structure
Authors: Kishimoto K , Yamamoto H , Akai K , Koyanagi T
Published: October 2012

Ge substitution for Sn in Ba8Ga16Sn30 was attempted in order to improve its thermoelectric properties. Since the melting point was raised by the substitution, the sintering temperature could be increased. The resultant sintered samples exhibited higher thermal stabilities and fewer trapping state densities at grain boundaries, which weakened grain boundary scattering for carriers. For example, the Ba8Ga16.4Sn25.0Ge4.6 and Ba8Ga16.9Sn19.8Ge9.3 samples had larger room temperature mobilities of 6.7 cm2 V−1 s−1 and 13.3 cm2 V−1 s−1, respectively, than that of 2.3 cm2 V−1 s−1 of the Ba8Ga16.6Sn29.4 sample. Consequently, these Ge-substituted samples had higher figures-of-merit maxima of 0.62 at 550 K and 0.63 at 600 K, respectively, than that of 0.36 at 500 K for the Ba8Ga16.6Sn29.4 sample.
A note on positive solutions for conservation laws with singular source
Authors: Amadori D. , Coclite G.
Published: October 2012

We consider the Cauchy problem for the scalar conservation law<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="partial-differential Subscript t Baseline u plus partial-differential Subscript x Baseline f left-parenthesis u right-parenthesis equals StartFraction 1 Over g left-parenthesis u right-parenthesis EndFraction comma t greater-than 0 comma x element-of double-struck upper R comma">∂tu+∂xf(u)=1g(u),t>0, x∈R,\begin{equation*} \partial _t u+\partial _x f(u) =\displaystyle \frac {1}{g(u)},\qquad t>0,\ x\in \mathbb {R}, \end{equation*}withg∈C1(R)g\in C^1(\mathbb {R}),g(0)=0g(0)=0,g(u)>0g(u)>0foru>0u>0, and assume that the initial datumu0u_0is nonnegative.

We show the existence of entropy solutions that are positive a.e. by means of an approximation of the equation that preserves positive solutions and by passing to the limit using a monotonicity argument. The difficulty lies in handling the singularity of the right-hand side (the source term) asuupossibly vanishes at the initial time. The source term is shown to be locally integrable.

Moreover, we prove a uniqueness and stability result for the above equation.
CD-HIT: accelerated for clustering the next-generation sequencing data
Authors: Fu Limin , Niu Beifang , Zhu Zhengwei , Wu Sitao , Li Weizhong
Published: October 2012

Summary: CD-HIT is a widely used program for clustering biological sequences to reduce sequence redundancy and improve the performance of other sequence analyses. In response to the rapid increase in the amount of sequencing data produced by the next-generation sequencing technologies, we have developed a new CD-HIT program accelerated with a novel parallelization strategy and some other techniques to allow efficient clustering of such datasets. Our tests demonstrated very good speedup derived from the parallelization for up to ∼24 cores and a quasi-linear speedup for up to ∼8 cores. The enhanced CD-HIT is capable of handling very large datasets in much shorter time than previous versions.

Availability:  http://cd-hit.org.

Contact:  liwz@sdsc.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Vetoes, Bargaining, and Boundary Conditions
Authors: Cameron Charles M.
Published: October 2012

“Testing Theories of Congressional-Presidential Interaction with Veto Override Rates” (henceforth “Veto Override Rates”) offers several tests of two models of vetoes and finds the models wanting. The paper concludes that something is seriously amiss with the models. In my view, the problem lies not in the models but in the tests. Understanding why the tests miss the mark is helpful in understanding models of veto politics, and more generally in thinking about testing strategies when multiple models analyze different causal mechanisms that hold under different circumstances. I should note immediately that the effort in the paper to think hard about override rates is admirable; it simply does not go far enough.
First Report of Gladiolus Corm Rot Caused by Fusarium proliferatum in Oman
Authors: Mahmooli I. H. Al , Balushi F. Al , Doyle O. , Sadi A. M. Al , Deadman M. L.
Published: October 2012

Hybrid gladiolus varieties have potential as a major ornamental crop in Oman. Grown for the cut-flower industry, their production has increased significantly in recent years. In 2010, during a field trial of two hybrid varieties (Red Majesty and Mascagni) grown in sandy soil at Al Moballah, Muscat, approximately 3% of Red Majesty plants and 12% of Mascagni plants showed signs of wilting and yellowing prior to plant death. In all cases, tissue taken from 20 diseased corms yielded Fusarium-like colonies on potato dextrose agar (PDA). Colonies were light to dark purple in color with dense and abundant aerial mycelium; macroconidia were 33.8 × 4.8 μm with 3 to 5 septa per spore; microconidia were 13.5 × 4.8 μm with 0 to 1 septa per spore and were in chains (mean of 50 spores in both cases). No chlamydospores were observed. In vitro characters and spore measurements conformed to previously described features of Fusarium proliferatum (Matsushima) Nirenberg (2). Mycelial plugs (5 mm in diameter) were taken from 5-day-old cultures of F. proliferatum grown on 2.5% PDA and wrapped on the base of Gladiolus corms using Parafilm and wet cotton. The Parafilm was removed after 7 days of inoculation. The corms were kept in moistened polythene bags for and symptoms were recorded. Control corms were inoculated using PDA (1). Artificial inoculations resulted in rot symptoms on all corms within 14 days and fungal colonies identical to initial isolations were recovered from artificially infected corms. Rotting was not observed in corms inoculated using PDA alone. Identification of F. proliferatum was confirmed using sequences of the internal transcribed spacer (ITS) of the ribosomal DNA (ITS1 and ITS4 primers) and sequences of the translation elongation factor alpha (TEF-1) gene (EF-1-986 and EF-728 primers). The ITS and TEF-1 sequences were found to share 99.8% and 99.6% nucleotide similarity to previously published sequences of the ITS (HQ113948) and EF (JN092351) regions of F. proliferatum in GenBank, respectively. The ITS sequence of one isolate was assigned GenBank Accession No. JN86006. To our knowledge, this is the first report of the occurrence of F. proliferatum in Oman or in the Arabian Peninsula.

References: (1) C. Linfield. Ann. Appl. Biol. 121:175, 1983. (2) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University Press, USA, 1983.
First Report of Orobanche purpurea on Achillea wilhelmsii in Iran
Authors: Yousefi A. R. , Jamshidi K. , Oveisi M. , Karimojeni H. , Pouryosef M.
Published: October 2012

Achillea wilhelmsii C. Koch (Asteraceae) is a wild herb widely disturbed in Iran and known locally as yarrow. This plant is an important medicinal plant and it has been used for its analgesic, antiphlogistic, antispasmodic, and antibacterial effects in Iranian folk medicine. Field surveys revealed infestations of yarrow broomrape, Orobanche purpurea Jacq., on A. wilhelmsii plants in two locations in province of Zanjan (Zanjan, 36°37′19.85″ N, 48°27′16.87″ E, 1,707.4 m elevation, and Qolabar, 36°19′19.85″ N, 48°19′16.41″ E, 1,663.9 m elevation) in northwestern Iran in May 2012. The annual mean air temperature and the average maximum and minimum air temperatures were 11, 18, and 4°C, respectively. The annual mean precipitation was 298 mm. The infestation of A. wilhelmsii was confirmed by verifying the attachment of the yarrow broomrape to the A. wilhelmsii roots. Broomrape plant heights were between 24 and 37 cm. The stems were erect, unbranched, slender, and swollen near the base at contact with host, 0.5 to 10 mm diameter. The leaves were reduced to scale or bracts up to 10 to 15 mm long. The flowers were in dense terminal spikes, usually restricted to the top third or half of the shoot. There was one bract and two bracteoles surrounding each flower. The bracts measured 7 to 10 mm, had ovate lanceolates shorter than the calyces, and lanceolate bracteoles were 5 to 10 mm. The calyces were gamosepalous, entire, and whitish. Corollas were 13 to 18 mm long, and were dull bluish-purple with dark veins, suffused with whitish-yellow at the base. The upper part was slightly curved forwards. Stamens were epipetalous, inserted 4 to 7 mm above the corolla base, with filaments glabrous. The anthers were glabrous along sutures. Stigma lobes were white. Fruit was an oval capsule, 0.9 to 10 mm. Botanists at the College of Agriculture of Zanjan University confirmed the identity of O. purpurea. A. millefolium has been reported as a host plant for yarrow broomrape (1,2). However, to our knowledge, this is the first report of yarrow broomrape on A. wilhelmsii in Iran. Since production and farming of A. wilhelmsii as a medicinal plant has recently started on a commercial scale in Iran, the parasite weed could pose a serious threat to production of this plant.

References: (1) B. Prajs. Biodiv. Res. Conserve. 17:33, 2010. (2) J. Rumsey and S. L. Jury. Watsonia. 18:257, 1991.
Excision of the Posterior Longitudinal Ligament During Anterior Cervical Corpectomy
Authors: Daubs Michael D. , Patel Alpesh A. , Lawrence Brandon D. , Brodke Darrel S.
Published: October 2012

Study Design:

An in vitro biomechanical study of the cervical spine.

Objective:

To evaluate the biomechanical significance of the posterior longitudinal ligament (PLL) after anterior cervical corpectomy and reconstruction with a strut graft and anterior plate.

Summary of Background Data:

Routine excision of the PLL during anterior cervical corpectomy is controversial. Many surgeons believe that maintaining the PLL after cervical corpectomy adds stability to the reconstruction, whereas others believe it can be excised without sequelae. There are no biomechanical studies to our knowledge evaluating the biomechanical significance of excising the PLL during corpectomy and whether this affects the stability of a reconstruction consisting of a strut graft and anterior plate. The purpose of this study was to evaluate the biomechanical effects of PLL excision during a complete anterior cervical corpectomy reconstructed with a strut graft and anterior plate.

Methods:

Seven human cadaveric fresh-frozen cervical spines C2–T1 were tested for range of motion before surgery and reconstruction. A complete C6 corpectomy was performed and an interbody strut spacer with load cell was placed along with an anterior plate. Range of motion was measured with ±2.5 Nm of torque in flexion-extension, lateral bending, and axial rotation. Load-sharing data were recorded with incremental axial loads. The PLL was excised and range of motion and load-sharing testing was repeated.

Results:

There were no significant differences in range of motion or load sharing with an anterior corpectomy and reconstruction after PLL excision.

Conclusions:

Excision of the PLL during anterior cervical corpectomy reconstructed with a strut graft and anterior plate does not significantly affect the construct stability or load sharing of the graft.
Mutational effects depend on ploidy level: all else is not equal
Authors: Gerstein Aleeza C.
Published: October 2012

Ploidy is predicted to influence adaptation directly, yet whether single mutations behave the same in different ploidy backgrounds has not been well studied. It has often been assumed theoretically that aside from dominance, selective parameters do not differ between cells of varying ploidy. Using the budding yeastSaccharomyces cerevisiae, I compared the effect size of 20 adaptive mutations in haploids and homozygous diploids and found, surprisingly, that the same mutations often had a much larger effect in haploids than homozygous diploids. This empirical result demonstrates that it cannot be assumed that mutations will have the same effect in haploids and homozygous diploids.
Effects of Dual-Channel Functional Electrical Stimulation on Gait Performance in Patients with Hemiparesis
Authors: Springer Shmuel , Vatine Jean-Jacques , Lipson Ronit , Wolf Alon , Laufer Yocheved
Published: October 2012

The study objective was to assess the effect of functional electrical stimulation (FES) applied to the peroneal nerve and thigh muscles on gait performance in subjects with hemiparesis. Participants were 45 subjects (age 57.8 ± 14.8 years) with hemiparesis (5.37 ± 5.43 years since diagnosis) demonstrating a foot-drop and impaired knee control. Thigh stimulation was applied either to the quadriceps or hamstrings muscles, depending on the dysfunction most affecting gait. Gait was assessed during a two-minute walk test with/without stimulation and with peroneal stimulation alone. A second assessment was conducted after six weeks of daily use. The addition of thigh muscles stimulation to peroneal stimulation significantly enhanced gait velocity measures at the initial and second evaluation. Gait symmetry was enhanced by the dual-channel stimulation only at the initial evaluation, and single-limb stance percentage only at the second assessment. For example, after six weeks, the two-minute gait speed with peroneal stimulation and with the dual channel was 0.66 ± 0.30 m/sec and 0.70 ± 0.31 m/sec, respectively (). In conclusion, dual-channel FES may enhance gait performance in subjects with hemiparesis more than peroneal FES alone.
Comparative analysis of PET findings and clinical outcome in patients with primary mediastinal seminoma
Authors: Koizumi Tomonobu , Katou Akane , Ikegawa Kayoko , Kosaka Mitsuru , Tateishi Kazunari , Yokoyama Toshiki , Ushiki Atsuto , Kanda Shintaro , Tsushima Kenji , Yamamoto Hiroshi , Hanaoka Masayuki , Kubo Keishi , Yoshida Kazuo , Oguchi Kazuhiko
Published: October 2012

Background

Primary mediastinal seminoma is a rare neoplasm. Cisplatin‐based chemotherapy is the standard treatment, but management of post‐chemotherapy seminoma residuals is still controversial. We encountered four cases of primary mediastinal seminoma and reviewed the clinical characteristics and outcomes, focusing on tumor size and F‐18 fluorodeoxyglucose positron emission tomography (FDG‐PET) findings after chemotherapy.

Methods

A retrospective review was performed of four consecutive patients with primary mediastinal seminoma treated in our institution between 2006 and 2010. All patients were young adult males with a median age of 31.3 years (range: 20–46 years). All patients were treated with three to four cycles of a combination of cisplatin, bleomycin, and etoposide, and FDG‐PET was performed after chemotherapy.

Results

The response to chemotherapy was good in all patients. After chemotherapy, the findings of the FDG‐PET were negative in three subjects. Two of the patients, with tumors measuring over 30 mm, underwent surgical resection for the residual mass and revealed necrotic tissues and no viable cells. A third patient remained stable without salvage surgery. The size of the residual mass in the remaining patient was less than 30 mm, but the FDP‐PET result was positive and the mass considered inoperable because of the involvement of large vessels. Subsequently, radiotherapy was added for the residual tumor, but disease progression was seen seven months after the initiation of chemotherapy.

Conclusions

FDG‐PET findings after chemotherapy could be useful as a tool for the prediction of viable residual tumor in post chemotherapy residual mediastinal seminoma.
Microsatellite variation in the equine MHC
Authors: Brinkmeyer‐Langford C. L. , Cai J. J. , Gill C. A. , Skow L. C.
Published: October 2012

Genes within the major histocompatibility complex (MHC) encode proteins involved in innate and adaptive immune responses. Genetic variation in this region can influence the immune response of an individual animal to challenges from a variety of pathogens; however, a complete documentation of genetic variation in the MHC is lacking for most domestic animals, including horses. To provide additional genetic markers for study of the horse MHC, or ELA (equine lymphocyte antigen), we identified 37 polymorphic microsatellite repeats in ELA and used these variations separately and together with published SNPs to investigate linkage disequilibrium (LD) and haplotype structure in a sample of Thoroughbred horses. ELA SNPs alone detected little LD, but microsatellites, either separately or combined with SNPs, revealed substantially more LD. A subset of markers in very high LD across the breadth of ELA may be predictive of structural polymorphisms or linked epistases that are important drivers of haplotype structure in Thoroughbreds.
The Prevalence Of Cervical Regulatory T Cells in HPV‐Related Cervical Intraepithelial Neoplasia (CIN) Correlates Inversely with Spontaneous Regression of CIN
Authors: Kojima Satoko , Kawana Kei , Tomio Kensuke , Yamashita Aki , Taguchi Ayumi , Miura Shiho , Adachi Katsuyuki , Nagamatsu Takeshi , Nagasaka Kazunori , Matsumoto Yoko , Arimoto Takahide , Oda Katsutoshi , Wada‐Hiraike Osamu , Yano Tetsu , Taketani Yuji , Fujii Tomoyuki , Schust Danny J. , Kozuma Shiro
Published: October 2012

Problem

Local adaptive cervical regulatory T cells (Tregs) are the most likely direct suppressors of the immune eradication of cervical intraepithelial lesion (CIN). PD‐1 expression on T cells induces Tregs. No studies have quantitatively analyzed the Tregs and PD‐1+ cells residing in CIN lesions.

Method of study

Cervical lymphocytes were collected using cytobrushes from CIN patients and analyzed by FACS analysis. Comparisons were made between populations of cervical Tregs and PD‐1+ CD4+ T cells in CIN regressors and non‐regressors.

Results

A median of 11% of cervical CD4+ T cells were Tregs, while a median of 30% were PD‐1+ cells. The proportions of cervical CD4+ T cells that were Tregs and/or PD‐1+ cells were significantly lower in CIN regressors when compared with non‐regressors.

Conclusions

The prevalence of cervical tolerogenic T cells correlates inversely with spontaneous regression of CIN. Cervical Tregs may play an important role in HPV‐related neoplastic immunoevasion.