bluuebunny/crossref_metadata_2025 huggingface dataset:
Hierarchical self-assembly of nanoparticles in polymer matrix and the nature of the interparticle interaction
Authors: Lin Yu-Chiao , Chen Chun-Yu , Chen Hsin-Lung , Hashimoto Takeji , Chen Show-An , Li Yen-Cheng
Published: June 2015

Using small angle X-ray scattering (SAXS), we elucidated the spatial organization of palladium (Pd) nanoparticles (NPs) in the polymer matrix of poly(2-vinylpyridine) (P2VP) and the nature of inter-nanoparticle interactions, where the NPs were synthesized in the presence of P2VP by the reduction of palladium acetylacetonate (Pd(acac)2). The experimental SAXS profiles were analysed on the basis of a hierarchical structure model considering the following two types of interparticle potential: (i) hard-core repulsion only (i.e., the hard-sphere interaction) and (ii) hard-core repulsion together with an attractive potential well (i.e., the sticky hard-sphere interaction). The corresponding theoretical scattering functions, which were used for analysing the experimental SAXS profiles, were obtained within the context of the Percus-Yevick closure and the Ornstein-Zernike equation in the fundamental liquid theory. The analyses revealed that existence of the attractive potential well is indispensable to account for the experimental SAXS profiles. Moreover, the morphology of the hybrids was found to be characterized by a hierarchical structure with three levels, where about six primary NPs with the diameter of ca. 1.8 nm (level one) formed local clusters (level two), and these clusters aggregated to build up a large-scale mass-fractal structure (level three) with the fractal dimension of ca. 2.3. The scattering function developed here is of general use for quantitatively characterizing the morphological structures of polymer/NP hybrids and, in particular, for exploring the interaction potential of the NPs on the basis of the fundamental liquid theory.
A photoelastic measurement system for residual stress analysis in scintillating crystals by conoscopic imaging
Authors: Montalto L. , Paone N. , Scalise L. , Rinaldi D.
Published: June 2015

The assessment of the stress state of scintillating crystals is an important issue for producers as well as users of such materials, because residual stress may arise during growth process. In this paper, a measurement system, based on the use of a photoelastic, conoscopic optical setup, is proposed for the assessment of stress state in scintillating crystals. Local stress values can be measured on the crystal in order to observe their spatial distribution. With the proposed system, it is possible to vary the dimensions of the inspected measurement volume. It has been validated with reference to a known stress state induced in a birefringent crystal sample and it has been tested for the case of loaded and unloaded samples, showing sub-millimetric spatial resolution and stress uncertainty ≤0.25 MPa. The proposed measurement system is a valid method for the inspection of scintillating crystals required by producers and users of such materials.
Molecular recognition by van der Waals interaction between polymers with sequence-specific polarizabilities
Authors: Lu Bing-Sui , Naji Ali , Podgornik Rudolf
Published: June 2015

We analyze van der Waals interactions between two rigid polymers with sequence-specific, anisotropic polarizabilities along the polymer backbones, so that the dipole moments fluctuate parallel to the polymer backbones. Assuming that each polymer has a quenched-in polarizability sequence which reflects, for example, the polynucleotide sequence of a double-stranded DNA molecule, we study the van der Waals interaction energy between a pair of such polymers with rod-like structure for the cases where their respective polarizability sequences are (i) distinct and (ii) identical, with both zero and non-zero correlation length of the polarizability correlator along the polymer backbones in the latter case. For identical polymers, we find a novel r−5 scaling behavior of the van der Waals interaction energy for small inter-polymer separation r, in contradistinction to the r−4 scaling behavior of distinct polymers, with furthermore a pronounced angular dependence favoring attraction between sufficiently aligned identical polymers. Such behavior can assist the molecular recognition between polymers.
Equations of state of anhydrous AlF3 and AlI3: Modeling of extreme condition halide chemistry
Authors: Stavrou Elissaios , Zaug Joseph M. , Bastea Sorin , Crowhurst Jonathan C. , Goncharov Alexander F. , Radousky Harry B. , Armstrong Michael R. , Roberts Sarah K. , Plaue Jonathan W.
Published: June 2015

Pressure dependent angle-dispersive x-ray powder diffraction measurements of alpha-phase aluminum trifluoride (α-AlF3) and separately, aluminum triiodide (AlI3) were conducted using a diamond-anvil cell. Results at 295 K extend to 50 GPa. The equations of state of AlF3 and AlI3 were determined through refinements of collected x-ray diffraction patterns. The respective bulk moduli and corresponding pressure derivatives are reported for multiple orders of the Birch-Murnaghan (B-M), finite-strain (F-f), and higher pressure finite-strain (G-g) EOS analysis models. Aluminum trifluoride exhibits an apparent isostructural phase transition at approximately 12 GPa. Aluminum triiodide also undergoes a second-order atomic rearrangement: applied stress transformed a monoclinically distorted face centered cubic (fcc) structure into a standard fcc structural arrangement of iodine atoms. Results from semi-empirical thermochemical computations of energetic materials formulated with fluorine containing reactants were obtained with the aim of predicting the yield of halogenated products.
Indium and gallium diffusion through zirconia in the TiN/ZrO2/InGaAs stack
Authors: Ceballos-Sanchez O. , Martinez E. , Guedj C. , Veillerot M. , Herrera-Gomez A.
Published: June 2015

Angle-resolved X-ray Photoelectron Spectroscopy (ARXPS) was applied to the TiN/ZrO2/InGaAs stack to assess its thermal stability. Through a robust ARXPS analysis, it was possible to observe subtle effects such as the thermally induced diffusion of substrate atomic species (In and Ga) through the dielectric layer. The detailed characterization of the film structure allowed for assessing the depth profiles of the diffused atomic species by means of the scenarios-method. Since the quantification for the amount of diffused material was done at different temperatures, it was possible to obtain an approximate value of the activation energy for the diffusion of indium through zirconia. The result is very similar to the previously reported values for indium diffusion through alumina and through hafnia.
IR photodissociation spectroscopy of (OCS)n+ and (OCS)n− cluster ions: Similarity and dissimilarity in the structure of CO2, OCS, and CS2 cluster ions
Authors: Inokuchi Yoshiya , Ebata Takayuki
Published: June 2015

Infrared photodissociation (IRPD) spectra of (OCS)n+ and (OCS)n− (n = 2–6) cluster ions are measured in the 1000–2300 cm−1 region; these clusters show strong CO stretching vibrations in this region. For (OCS)2+ and (OCS)2−, we utilize the messenger technique by attaching an Ar atom to measure their IR spectra. The IRPD spectrum of (OCS)2+Ar shows two bands at 2095 and 2120 cm−1. On the basis of quantum chemical calculations, these bands are assigned to a C2 isomer of (OCS)2+, in which an intermolecular semi-covalent bond is formed between the sulfur ends of the two OCS components by the charge resonance interaction, and the positive charge is delocalized over the dimer. The (OCS)n+ (n = 3–6) cluster ions show a few bands assignable to “solvent” OCS molecules in the 2000–2080 cm−1 region, in addition to the bands due to the (OCS)2+ ion core at ∼2090 and ∼2120 cm−1, suggesting that the dimer ion core is kept in (OCS)3–6+. For the (OCS)n− cluster anions, the IRPD spectra indicate the coexistence of a few isomers with an OCS− or (OCS)2− anion core over the cluster range of n = 2–6. The (OCS)2−Ar anion displays two strong bands at 1674 and 1994 cm−1. These bands can be assigned to a Cs isomer with an OCS− anion core. For the n = 2–4 anions, this OCS− anion core form is dominant. In addition to the bands of the OCS− core isomer, we found another band at ∼1740 cm−1, which can be assigned to isomers having an (OCS)2− ion core; this dimer core has C2 symmetry and 2A electronic state. The IRPD spectra of the n = 3–6 anions show two IR bands at ∼1660 and ∼2020 cm−1. The intensity of the latter component relative to that of the former one becomes stronger and stronger with increasing the size from n = 2 to 4, which corresponds to the increase of “solvent” OCS molecules attached to the OCS− ion core, but it suddenly decreases at n = 5 and 6. These IR spectral features of the n = 5 and 6 anions are ascribed to the formation of another (OCS)2− ion core having C2v symmetry with 2B2 electronic state.
Fibril orientation redistribution induced by stretching of cellulose nanofibril hydrogels
Authors: Josefsson Gabriella , Ahvenainen Patrik , Mushi Ngesa Ezekiel , Gamstedt E. Kristofer
Published: June 2015

The mechanical performance of materials reinforced by cellulose nanofibrils is highly affected by the orientation of these fibrils. This paper investigates the nanofibril orientation distribution of films of partly oriented cellulose nanofibrils. Stripes of hydrogel films were subjected to different amount of strain and, after drying, examined with X-ray diffraction to obtain the orientation of the nanofibrils in the films, caused by the stretching. The cellulose nanofibrils had initially a random in-plane orientation in the hydrogel films and the strain was applied to the films before the nanofibrils bond tightly together, which occurs during drying. The stretching resulted in a reorientation of the nanofibrils in the films, with monotonically increasing orientation towards the load direction with increasing strain. Estimation of nanofibril reorientation by X-ray diffraction enables quantitative comparison of the stretch-induced orientation ability of different cellulose nanofibril systems. The reorientation of nanofibrils as a consequence of an applied strain is also predicted by a geometrical model of deformation of nanofibril hydrogels. Conversely, in high-strain cold-drawing of wet cellulose nanofibril materials, the enhanced orientation is promoted by slipping of the effectively stiff fibrils.
Relativistic electron scattering by magnetosonic waves: Effects of discrete wave emission and high wave amplitudes
Authors: Artemyev A. V. , Mourenas D. , Agapitov O. V. , Krasnoselskikh V. V.
Published: June 2015

In this paper, we study relativistic electron scattering by fast magnetosonic waves. We compare results of test particle simulations and the quasi-linear theory for different spectra of waves to investigate how a fine structure of the wave emission can influence electron resonant scattering. We show that for a realistically wide distribution of wave normal angles θ (i.e., when the dispersion δθ≥0.5°), relativistic electron scattering is similar for a wide wave spectrum and for a spectrum consisting in well-separated ion cyclotron harmonics. Comparisons of test particle simulations with quasi-linear theory show that for δθ>0.5°, the quasi-linear approximation describes resonant scattering correctly for a large enough plasma frequency. For a very narrow θ distribution (when δθ∼0.05°), however, the effect of a fine structure in the wave spectrum becomes important. In this case, quasi-linear theory clearly fails in describing accurately electron scattering by fast magnetosonic waves. We also study the effect of high wave amplitudes on relativistic electron scattering. For typical conditions in the earth's radiation belts, the quasi-linear approximation cannot accurately describe electron scattering for waves with averaged amplitudes >300 pT. We discuss various applications of the obtained results for modeling electron dynamics in the radiation belts and in the Earth's magnetotail.
Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas
Authors: Mikkelsen D. R. , Bitter M. , Delgado-Aparicio L. , Hill K. W. , Greenwald M. , Howard N. T. , Hughes J. W. , Rice J. E. , Reinke M. L. , Podpaly Y. , Ma Y. , Candy J. , Waltz R. E.
Published: June 2015

Peaked density profiles in low-collisionality AUG and JET H-mode plasmas are probably caused by a turbulently driven particle pinch, and Alcator C-Mod experiments confirmed that collisionality is a critical parameter. Density peaking in reactors could produce a number of important effects, some beneficial, such as enhanced fusion power and transport of fuel ions from the edge to the core, while others are undesirable, such as lower beta limits, reduced radiation from the plasma edge, and consequently higher divertor heat loads. Fundamental understanding of the pinch will enable planning to optimize these impacts. We show that density peaking is predicted by nonlinear gyrokinetic turbulence simulations based on measured profile data from low collisionality H-mode plasma in Alcator C-Mod. Multiple ion species are included to determine whether hydrogenic density peaking has an isotope dependence or is influenced by typical levels of low-Z impurities, and whether impurity density peaking depends on the species. We find that the deuterium density profile is slightly more peaked than that of hydrogen, and that experimentally relevant levels of boron have no appreciable effect on hydrogenic density peaking. The ratio of density at r/a = 0.44 to that at r/a = 0.74 is 1.2 for the majority D and minority H ions (and for electrons), and increases with impurity Z: 1.1 for helium, 1.15 for boron, 1.3 for neon, 1.4 for argon, and 1.5 for molybdenum. The ion temperature profile is varied to match better the predicted heat flux with the experimental transport analysis, but the resulting factor of two change in heat transport has only a weak effect on the predicted density peaking.
Direction dependent thermal conductivity of monolayer phosphorene: Parameterization of Stillinger-Weber potential and molecular dynamics study
Authors: Xu Wen , Zhu Liyan , Cai Yongqing , Zhang Gang , Li Baowen
Published: June 2015

A Stillinger-Weber interatomic potential is parameterized for phosphorene. It well reproduces the crystal structure, cohesive energy, and phonon dispersion predicted by first-principles calculations. The thermal conductivity of phosphorene is explored by equilibrium molecular dynamics simulations adopting the optimal set of potential parameters. At room temperature, the intrinsic thermal conductivities along zigzag and armchair directions are about 152.7 and 33.0 W/mK, respectively, with a large anisotropy ratio of five. The remarkably directional dependence of thermal conductivity in phosphorene, consistent with previous reports, is mainly due to the strong anisotropy of phonon group velocities, and weak anisotropy of phonon lifetimes as revealed by lattice dynamics calculations. Moreover, the effective phonon mean free paths at zigzag and armchair directions are about 141.4 and 43.4 nm, respectively.
Atomic-layer deposited thulium oxide as a passivation layer on germanium
Authors: Mitrovic I. Z. , Hall S. , Althobaiti M. , Hesp D. , Dhanak V. R. , Santoni A. , Weerakkody A. D. , Sedghi N. , Chalker P. R. , Henkel C. , Dentoni Litta E. , Hellström P.-E. , Östling M. , Tan H. , Schamm-Chardon S.
Published: June 2015

A comprehensive study of atomic-layer deposited thulium oxide (Tm2O3) on germanium has been conducted using x-ray photoelectron spectroscopy (XPS), vacuum ultra-violet variable angle spectroscopic ellipsometry, high-resolution transmission electron microscopy (HRTEM), and electron energy-loss spectroscopy. The valence band offset is found to be 3.05 ± 0.2 eV for Tm2O3/p-Ge from the Tm 4d centroid and Ge 3p3/2 charge-corrected XPS core-level spectra taken at different sputtering times of a single bulk thulium oxide sample. A negligible downward band bending of ∼0.12 eV is observed during progressive differential charging of Tm 4d peaks. The optical band gap is estimated from the absorption edge and found to be 5.77 eV with an apparent Urbach tail signifying band gap tailing at ∼5.3 eV. The latter has been correlated to HRTEM and electron diffraction results corroborating the polycrystalline nature of the Tm2O3 films. The Tm2O3/Ge interface is found to be rather atomically abrupt with sub-nanometer thickness. In addition, the band line-up of reference GeO2/n-Ge stacks obtained by thermal oxidation has been discussed and derived. The observed low reactivity of thulium oxide on germanium as well as the high effective barriers for holes (∼3 eV) and electrons (∼2 eV) identify Tm2O3 as a strong contender for interfacial layer engineering in future generations of scaled high-κ gate stacks on Ge.
Suppression of metastable-phase inclusion in N-polar (0001¯) InGaN/GaN multiple quantum wells grown by metalorganic vapor phase epitaxy
Authors: Shojiki Kanako , Choi Jung-Hun , Iwabuchi Takuya , Usami Noritaka , Tanikawa Tomoyuki , Kuboya Shigeyuki , Hanada Takashi , Katayama Ryuji , Matsuoka Takashi
Published: June 2015

The metastable zincblende (ZB) phase in N-polar (0001¯) (−c-plane) InGaN/GaN multiple quantum wells (MQWs) grown by metalorganic vapor phase epitaxy is elucidated by the electron backscatter diffraction measurements. From the comparison between the −c-plane and Ga-polar (0001) (+c-plane), the −c-plane MQWs were found to be suffered from the severe ZB-phase inclusion, while ZB-inclusion is negligible in the +c-plane MQWs grown under the same growth conditions. The ZB-phase inclusion is a hurdle for fabricating the −c-plane light-emitting diodes because the islands with a triangular shape appeared on a surface in the ZB-phase domains. To improve the purity of stable wurtzite (WZ)-phase, the optimum conditions were investigated. The ZB-phase is dramatically eliminated with decreasing the V/III ratio and increasing the growth temperature. To obtain much-higher-quality MQWs, the thinner InGaN wells and the hydrogen introduction during GaN barriers growth were tried. Consequently, MQWs with almost pure WZ phase and with atomically smooth surface have been demonstrated.
Computational study of plasma actuator on film cooling performance for different shaped holes
Authors: Dai Sheng-ji , Xiao Yang , He Li-ming , Jin Tao , Hou Peng-hui , Zhang Qian , Zhao Zi-chen
Published: June 2015

An investigation on film cooling holes with plasma actuators are performed for circular hole, expansion-shaped hole and fan-shaped hole on the surface of flat plate. The results are compared with those obtained from the same combination of varied shaped holes without plasma actuator. Computational results suggest that plasma-induced body force mitigates the intensity of the counter rotating vortex pair by creating a new pair of vortexes, thereby providing greater coolant-surface attachment for each hole shape, resulting in the improvement of film cooling effectiveness. As for the holes of varied shapes with plasma actuator, the expansion-shaped hole shows superior laterally averaged film cooling effectiveness to that of the circular hole. Comparing with the abovementioned two shaped holes, the fan-shaped one performs worse in terms of laterally averaged film cooling effectiveness at low blow ratios, and better at high blow ratios. The fan-shaped hole also provides the best uniformity of film cooling effectiveness among all cases.
Spectral interference of terahertz pulses from two laser filaments in air
Authors: Chen Yanping , Zhang Zhelin , Zhang Zhen , Yuan Xiaohui , Liu Feng , Chen Min , Xu Jianqiu , Yu Jin , Sheng Zhengming , Zhang Jie
Published: June 2015

Spectral interference is experimentally demonstrated by two terahertz pulses emitting from filaments induced by two successive femtosecond laser pulses in air. Here, a leading pulse is set to be weaker than a trailing pulse and their temporal separation is larger than the pulse duration of the terahertz pulses. When the leading pulse is stronger than the trailing pulse, the frequency modulation within the whole terahertz envelope is greatly deteriorated due to nonlinear effects applying on the trailing pulse through the plasmas generated by the leading pulses. Such unique terahertz spectrum may find applications in terahertz spectroscopy.
Optical feedback cavity-enhanced absorption spectroscopy with a 3.24 μm interband cascade laser
Authors: Manfred K. M. , Ritchie G. A. D. , Lang N. , Röpcke J. , van Helden J. H.
Published: June 2015

The development of interband cascade lasers (ICLs) has made the strong C-H transitions in the 3 μm spectral region increasingly accessible. We present the demonstration of a single mode distributed feedback ICL coupled to a V-shaped optical cavity in an optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS) experiment. We achieved a minimum detectable absorption coefficient, αmin, of (7.1±0.2)×10−8 cm−1 for a spectrum of CH4 at 3.24 μm with a two second acquisition time (100 scans averaged). This corresponds to a detection limit of 3 ppb CH4 at atmospheric pressure, which is comparable to previously reported OF-CEAS instruments with diode lasers or quantum cascade lasers. The ability to frequency lock an ICL source in the important 3 μm region to an optical cavity holds great promise for future spectroscopic applications.
Self-rectifying resistive-switching characteristics with ultralow operating currents in SiOxNy/AlN bilayer devices
Authors: Kwon Jeong Yong , Park Ju Hyun , Kim Tae Geun
Published: June 2015

We propose a SiOxNy/AlN bilayer resistive switching random access memory scheme to eliminate crosstalk in a crossbar array structure. We demonstrated forming-free self-rectifying behaviors at an ultralow operating current (below 200 nA) by optimizing the current compliance and operating voltage. The set and reset voltages were reduced using a thin AlN layer, and the voltages' on/off ratio and rectifying ratio were as high as 80 and 102, respectively. In addition, the device showed an endurance of 103 dc cycles and a retention time over 105 s.
High quality, giant crystalline-Ge stripes on insulating substrate by rapid-thermal-annealing of Sn-doped amorphous-Ge in solid-liquid coexisting region
Authors: Matsumura Ryo , Kai Yuki , Chikita Hironori , Sadoh Taizoh , Miyao Masanobu
Published: June 2015

Formation of large-grain (≥30 μm) Ge crystals on insulating substrates is strongly desired to achieve high-speed thin-film transistors. For this purpose, we propose the methods of Sn-doping into amorphous-Ge combined with rapid-thermal-annealing (RTA) in the solid-liquid coexisting temperature region for the Ge-Sn alloy system. The densities of micro-crystal-nuclei formed in this temperature region become low by tuning the RTA temperature close to the liquidus curve, which enhances the lateral growth of GeSn. Thanks to the very small segregation coefficient of Sn, almost all Sn atoms segregate toward edges of the stripes during growth. Agglomeration of GeSn degrades the surface morphologies; however, it is significantly improved by lowering the initial Sn concentration. As a result, pure Ge with large crystal grains (∼40 μm) with smooth surface are obtained by optimizing the initial Sn concentration as low as 3 ∼ 5%. Lateral growth lengths are further increased through decreasing the number of nuclei in stripes by narrowing stripe width. In this way, high-crystallinity giant Ge crystals (∼200 μm) are obtained for the stripe width of 3 μm. This “Si-seed free” technique for formation of large-grain pure Ge crystals is very useful to realize high-performance thin-film devices on insulator.
Extending the diffusion approximation to the boundary using an integrated diffusion model
Authors: Chen Chen , Du Zhidong , Pan Liang
Published: June 2015

The widely used diffusion approximation is inaccurate to describe the transport behaviors near surfaces and interfaces. To solve such stochastic processes, an integro-differential equation, such as the Boltzmann transport equation (BTE), is typically required. In this work, we show that it is possible to keep the simplicity of the diffusion approximation by introducing a nonlocal source term and a spatially varying diffusion coefficient. We apply the proposed integrated diffusion model (IDM) to a benchmark problem of heat conduction across a thin film to demonstrate its feasibility. We also validate the model when boundary reflections and uniform internal heat generation are present.
Highly aligned arrays of high aspect ratio barium titanate nanowires via hydrothermal synthesis
Authors: Bowland Christopher C. , Malakooti Mohammad H. , Zhou Zhi , Sodano Henry A.
Published: June 2015

We report on the development of a hydrothermal synthesis procedure that results in the growth of highly aligned arrays of high aspect ratio barium titanate nanowires. Using a multiple step, scalable hydrothermal reaction, a textured titanium dioxide film is deposited on titanium foil upon which highly aligned nanowires are grown via homoepitaxy and converted to barium titanate. Scanning electron microscope images clearly illustrate the effect the textured film has on the degree of orientation of the nanowires. The alignment of nanowires is quantified by calculating the Herman's Orientation Factor, which reveals a 58% improvement in orientation as compared to growth in the absence of the textured film. The ferroelectric properties of barium titanate combined with the development of this scalable growth procedure provide a powerful route towards increasing the efficiency and performance of nanowire-based devices in future real-world applications such as sensing and power harvesting.
Tunnel magnetoresistance in thermally robust Mo/CoFeB/MgO tunnel junction with perpendicular magnetic anisotropy
Authors: Fang B. , Zhang X. , Zhang B. S. , Zeng Z. M. , Cai J. W.
Published: June 2015

We report on tunnel magnetoresistance and electric-field effect in the Mo buffered and capped CoFeB/MgO magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy. A large tunnel magnetoresistance of 120% is achieved. Furthermore, this structure shows greatly improved thermal stability and stronger electric-field-induced modulation effect in comparison with the Ta/CoFeB/MgO-based MTJs. These results suggest that the Mo-based MTJs are more desirable for next generation spintronic devices.
Velocity overshoot decay mechanisms in compound semiconductor field-effect transistors with a submicron characteristic length
Authors: Jyegal Jang
Published: June 2015

Velocity overshoot is a critically important nonstationary effect utilized for the enhanced performance of submicron field-effect devices fabricated with high-electron-mobility compound semiconductors. However, the physical mechanisms of velocity overshoot decay dynamics in the devices are not known in detail. Therefore, a numerical analysis is conducted typically for a submicron GaAs metal-semiconductor field-effect transistor in order to elucidate the physical mechanisms. It is found that there exist three different mechanisms, depending on device bias conditions. Specifically, at large drain biases corresponding to the saturation drain current (dc) region, the velocity overshoot suddenly begins to drop very sensitively due to the onset of a rapid decrease of the momentum relaxation time, not the mobility, arising from the effect of velocity-randomizing intervalley scattering. It then continues to drop rapidly and decays completely by severe mobility reduction due to intervalley scattering. On the other hand, at small drain biases corresponding to the linear dc region, the velocity overshoot suddenly begins to drop very sensitively due to the onset of a rapid increase of thermal energy diffusion by electrons in the channel of the gate. It then continues to drop rapidly for a certain channel distance due to the increasing thermal energy diffusion effect, and later completely decays by a sharply decreasing electric field. Moreover, at drain biases close to a dc saturation voltage, the mechanism is a mixture of the above two bias conditions. It is suggested that a large secondary-valley energy separation is essential to increase the performance of submicron devices.
Too hot to trot? Evaluating the effects of wildfire on patterns of occupancy and abundance for a climate-sensitive habitat specialist
Authors: Varner Johanna , Lambert Mallory S. , Horns Joshua J. , Laverty Sean , Dizney Laurie , Beever Erik A. , Dearing M. Denise
Published: June 2015

Wildfires are increasing in frequency and severity as a result of climate change in many ecosystems; however, effects of altered disturbance regimes on wildlife remain poorly quantified. Here, we leverage an unexpected opportunity to investigate how fire affects the occupancy and abundance of a climate-sensitive habitat specialist, the American pika (Ochotona princeps). We determine the effects of a fire on microclimates within talus and explore habitat factors promoting persistence and abundance in fire-affected habitat. During the fire, temperatures in talus interstices remained below 19°C, suggesting that animals could have survived in situ. Within 2 years, pikas were widely distributed throughout burned areas and did not appear to be physiologically stressed at severely burned sites. Furthermore, pika densities were better predicted by topographic variables known to affect this species than by metrics of fire severity. This widespread distribution may reflect quick vegetation recovery and the fact that the fire did not alter the talus microclimates in the following years. Together, these results highlight the value of talus as a thermal refuge for small animals during and after fire. They also underscore the importance of further study in individual species’ responses to typical and altered disturbance regimes.
Muskellunge and Northern Pike Ecology and Management: Important Issues and Research Needs
Authors: Crane Derek P. , Miller Loren M. , Diana James S. , Casselman John M. , Farrell John M. , Kapuscinski Kevin L. , Nohner Joe K.
Published: June 2015

New research techniques and changing Muskellunge Esox masquinongy and Northern Pike E. lucius fisheries have contributed to paradigm shifts in the science and management of these species. A symposium on Muskellunge and Northern Pike biology, ecology and management was held at the American Fisheries Society Annual Meeting in Little Rock, Arkansas, and a panel discussion following the symposium identified several research and management priorities, including spawning habitat identification, habitat and population restoration, genetics, and selective mortality and exploitation. Future Muskellunge and Northern Pike research should focus on quantifying egg and age-0 survival based on habitat characteristics, rigorously evaluating habitat restoration efforts using statistically sound study designs, describing range-wide genetic structure of populations, and developing a better understanding of how selective mortality and exploitation can alter population size structure, sex ratios, and life history characteristics. Information and outcomes from the proposed research and management priorities will be critical for conserving and restoring self-sustaining populations of Muskellunge and Northern Pike.

Las nuevas técnicas de investigación y los cambios en las pesquerías de los lucios muskallonga, Esox masquinongy y europeo, E. lucius, han contribuido a modificar paradigmas sobre la ciencia y manejo de estas especies. Se llevó a cabo un simposio sobre biología, ecología y manejo de los lucios muskallonga y europeo en la reunión anual de la Sociedad Americana de Pesquerías, en Little Rock, Arkansas, y en un panel de discusión organizado después del simposio se identificaron diversas prioridades de investigación y manejo que incluyen identificación de hábitats de desove, restauración de hábitats y de poblaciones, genética, mortalidad selectiva y explotación. En el futuro, la investigación sobre los lucios muskallonga y europeo se debe enfocar en cuantificar la supervivencia a nivel de huevos y de edad O; sobre la base de las características del hábitat, evaluar rigurosamente los esfuerzos de restauración de hábitat mediante diseño de sondeos estadísticos, descripción amplia de la estructuración genética de las poblaciones y desarrollar un mejor entendimiento acerca de cómo la mortalidad selectiva y la explotación pueden alterar la estructura de tallas, proporción de sexos y características de la historia de vida de estas especies. Los resultados y la información que se genere tanto de la investigación propuesta como de las prioridades de manejo, serán críticos para la conservación y restauración de las poblaciones auto sostenibles de los lucios muskallonga y europeo.
Simulating sustainability: a resources perspective
Authors: Grace William
Published: June 2015

A global population-economy-resource model explores the future impact of declining resource availability on the world economy. The model tracks the likely future consumption of renewable resources, fossil fuels and non-renewable materials and the economic impact of availability. Scarcity will likely become evident during the latter part of this century and constrain economic production, reducing income per capita, living standards and ultimately population. Policy interventions involving a rapid transition from fossil fuels to renewable energy, reduced resource intensity and materials recycling are necessary to correct this trajectory and facilitate ongoing improvements in global average living standards.
Incoherent Texts? Storytelling, Preaching, and theCent nouvelles nouvellesin Marguerite de Navarre’sHeptaméron21*
Authors: Ridder-Vignone António De
Published: June 2015

To analyze Marguerite de Navarre’s response to the misogynist francophone novella tradition, this article asks how material provided by oldernouvellesis reorganized in theHeptaméron, blurring both normative definitions of masculinity and femininity and the lines between framed novellas and other genres. This article describes Marguerite’s use of nonfictional sources as well asCent nouvelles nouvelles26. Visual iconographic transformations in theCent nouvelles nouvellesare converted in theHeptaméroninto textual and intergeneric transformations. In the distance betweenCent nouvelles nouvelles26’s elaborate crossdressing farce andHeptaméron21, which blends romance, pardon request, and martyr’s tale, one perceives the differences in gendered thought and rhetorical strategy separating Marguerite from her anonymous predecessors.
The Homeric Question in the Sixteenth Century: Early Modern Scholarship and the Text of Homer*
Authors: Demetriou Tania
Published: June 2015

Gerard Falkenburg’s annotations on Homer reveal a type of philology rare in the Renaissance: Falkenburg probed the epics’ histories by analyzing their textual fault lines, as F. A. Wolf would do in 1795 when he revolutionized the study of Homer. Following in the footsteps of certain other scholars, Falkenburg alone arrived at a methodology for this sort of work, without publishing his observations. Obertus Giphanius did use them liberally in his 1572 commentary on Homer and his short preface to this is often noted as a mysterious forerunner to the Homeric Question. But if this previously unnoticed scholarship contextualizes famous early modern insights on the Homeric Question like Giphanius’s, one important reason it was not taken further lies with Giphanius’s flawed grasp and transmission of the technical innovations in Falkenburg’s work.
A web application for the unspecific detection of differentially expressed DNA regions in strand-specific expression data
Authors: Juanes José M. , Miguel Ana , Morales Lucas J. , Pérez-Ortín José E. , Arnau Vicente
Published: June 2015

Genomic technologies allow laboratories to produce large-scale data sets, either through the use of next-generation sequencing or microarray platforms. To explore these data sets and obtain maximum value from the data, researchers view their results alongside all the known features of a given reference genome. To study transcriptional changes that occur under a given condition, researchers search for regions of the genome that are differentially expressed between different experimental conditions. In order to identify these regions several algorithms have been developed over the years, along with some bioinformatic platforms that enable their use. However, currently available applications for comparative microarray analysis exclusively focus on changes in gene expression within known transcribed regions of predicted protein-coding genes, the changes that occur in non-predictable genetic elements, such as non-coding RNAs. Here, we present a web application for the visualization of strand-specific tiling microarray or next-generation sequencing data that allows customized detection of differentially expressed regions all along the genome in an unspecific manner, that allows identification of all RNA sequences, predictable or not.

Availability and implementation: The web application is freely accessible at http://tilingscan.uv.es/. TilingScan is implemented in PHP and JavaScript.

Contact:  vicente.arnau@uv.es

Supplementary information:  Supplementary data are available at Bioinformatics online.
The projack: a resampling approach to correct for ranking bias in high-throughput studies
Authors: Zhou Yi-Hui , Wright Fred A.
Published: June 2015

The problem of ranked inference arises in a number of settings, for which the investigator wishes to perform parameter inference after ordering a set of $m$ statistics. In contrast to inference for a single hypothesis, the ranking procedure introduces considerable bias, a problem known as the “winner's curse” in genetic association. We introduce the projack (for Prediction by Re- Ordered Jackknife and Cross-Validation, $K$-fold). The projack is a resampling-based procedure that provides low-bias estimates of the expected ranked effect size parameter for a set of possibly correlated $z$ statistics. The approach is flexible, and has wide applicability to high-dimensional datasets, including those arising from genomics platforms. Initially, motivated for the setting where original data are available for resampling, the projack can be extended to the situation where only the vector of $z$ values is available. We illustrate the projack for correction of the winner's curse in genetic association, although it can be used much more generally.
Quantile regression in the presence of monotone missingness with sensitivity analysis
Authors: Liu Minzhao , Daniels Michael J. , Perri Michael G.
Published: June 2015

In this paper, we develop methods for longitudinal quantile regression when there is monotone missingness. In particular, we propose pattern mixture models with a constraint that provides a straightforward interpretation of the marginal quantile regression parameters. Our approach allows sensitivity analysis which is an essential component in inference for incomplete data. To facilitate computation of the likelihood, we propose a novel way to obtain analytic forms for the required integrals. We conduct simulations to examine the robustness of our approach to modeling assumptions and compare its performance to competing approaches. The model is applied to data from a recent clinical trial on weight management.
Loss of Vancomycin-Resistant Enterococcus Fecal Dominance in an Organ Transplant Patient With Clostridium difficile Colitis After Fecal Microbiota Transplant
Authors: Stripling Joshua , Kumar Ranjit , Baddley John W. , Nellore Anoma , Dixon Paula , Howard Donna , Ptacek Travis , Lefkowitz Elliot J. , Tallaj Jose A. , Benjamin William H. , Morrow Casey D. , Rodriguez J. Martin
Published: June 2015

We report the use of fecal microbiota transplantation in a single heart-kidney transplant recipient with recurrent Clostridium difficile, vancomycin-resistant Enterococcus (VRE) fecal dominance, and recurrent VRE infections. Fecal microbiota transplantation resulted in the reconstruction of a diverse microbiota with (1) reduced relative abundance of C difficile and VRE and (2) positive clinical outcome.
Variable selection for modeling the absolute magnitude at maximum of Type Ia supernovae
Authors: Uemura Makoto , Kawabata Koji S. , Ikeda Shiro , Maeda Keiichi
Published: June 2015

We discuss what is an appropriate set of explanatory variables in order to predict the absolute magnitude at the maximum of Type Ia supernovae. In order to have a good prediction, the error for future data, which is called the “generalization error,” should be small. We use cross-validation in order to control the generalization error and a LASSO-type estimator in order to choose the set of variables. This approach can be used even in the case that the number of samples is smaller than the number of candidate variables. We studied the Berkeley supernova database with our approach. Candidates for the explanatory variables include normalized spectral data, variables about lines, and previously proposed flux ratios, as well as the color and light-curve widths. As a result, we confirmed the past understanding about Type Ia supernovae: (i) The absolute magnitude at maximum depends on the color and light-curve width. (ii) The light-curve width depends on the strength of Si ii. Recent studies have suggested adding more variables in order to explain the absolute magnitude. However, our analysis does not support adding any other variables in order to have a better generalization error.
Metal enrichment in the Fermi bubbles as a probe of their origin
Authors: Inoue Yoshiyuki , Nakashima Shinya , Tahara Masaya , Kataoka Jun , Totani Tomonori , Fujita Yutaka , Sofue Yoshiaki
Published: June 2015

The Fermi bubbles are gigantic gamma-ray structures in our Galaxy. The physical origin of the bubbles is still under debate. The leading scenarios can be divided into two categories. One is nuclear star-forming activity similar to extragalactic starburst galaxies and the other is past active galactic nucleus (AGN)-like activity of the Galactic center supermassive black hole. In this letter, we propose that metal abundance measurements will provide an important clue to probe their origin. Based on a simple spherically symmetric bubble model, we find that the generated metallicity and abundance patterns of the bubbles’ gas strongly depend on assumed star formation or AGN activities. Star formation scenarios predict higher metallicities and abundance ratios of [O/Fe] and [Ne/Fe] than AGN scenarios do because of supernovae ejecta. Furthermore, the resultant abundance depends on the gamma-ray emission process because different mass injection histories are required for the different gamma-ray emission processes due to the acceleration and cooling time scales of non-thermal particles. Future X-ray missions such as ASTRO-H and Athena will give a clue to probe the origin of the bubbles through abundance measurements with their high energy resolution instruments.
Cosmological constraints from Subaru weak lensing cluster counts
Authors: Hamana Takashi , Sakurai Junya , Koike Michitaro , Miller Lance
Published: June 2015

We present results of weak lensing cluster counts obtained from 11-degree2 Subaru/SuprimeCam data. Although the area is much smaller than previous work dealing with weak lensing peak statistics, the number density of galaxies usable for weak lensing analysis is about twice as large. The higher galaxy number density reduces the noise in the weak lensing mass maps, and thus increases the signal-to-noise ratio (S/N) of peaks of the lensing signal due to massive clusters. This enables us to construct a weak lensing selected cluster sample by adopting a high threshold S/N, such that the contamination rate due to false signals is small. We find six peaks with S/N > 5. For all the peaks, previously identified clusters of galaxies are matched within a separation of 1′, demonstrating good correspondence between the peaks and clusters of galaxies. We evaluate the statistical error in the weak lensing cluster counts using mock weak lensing data generated from full-sky ray-tracing simulations, and find Npeak = 6 ± 3.1 in an effective area of 9.0 degree2. We compare the measured weak lensing cluster counts with the theoretical model prediction based on halo models and place the constraint on the Ωm–σ8 plane which is found to be consistent with currently standard ΛCDM models. It is demonstrated that the weak lensing cluster counts can place a unique constraint on the σ8–c0 plane, where c0 is the normalization of the dark matter halo mass–concentration relationship. Finally we discuss prospects for ongoing/future wide field optical galaxy surveys.
A Perioperative Course of Gabapentin Does Not Produce a Clinically Meaningful Improvement in Analgesia after Cesarean Delivery
Authors: Monks David T. , Hoppe David W. , Downey Kristi , Shah Vibhuti , Bernstein Paul , Carvalho Jose C. A.
Published: June 2015

AbstractAbstract

In 197 women randomized to receive gabapentin, 600 mg before cesarean delivery and 200 mg every 8 h for 2 days postoperatively or placebo, there was a statistically significant but clinically unimportant difference in pain with movement 24 h after surgery. Sedation was greater in women treated with gabapentin.

Background:

Studies examining the efficacy of a single preoperative dose of gabapentin for analgesia after cesarean delivery (CD) have been inconclusive. The authors hypothesized that a perioperative course of gabapentin would improve analgesia after CD.

Methods:

This single-center, randomized, double-blind, placebo-controlled, parallel-group, superiority trial was designed to determine the analgesic efficacy of a perioperative course of gabapentin when added to a multimodal analgesic regimen. Women scheduled for elective CD during spinal anesthesia were randomized to receive a perioperative oral course of either gabapentin (600 mg preoperatively followed by 200 mg every 8 h for 2 days) or placebo. Postoperative pain was measured at 24 and 48 h, at rest and on movement, on a visual analogue scale (VAS, 0 to 100 mm). The primary outcome was pain on movement at 24 h. Neonatal outcomes, opiate consumption, VAS satisfaction (0 to 100 mm), adverse effects, and persistent pain were also assessed.

Results:

Baseline characteristics were similar between groups. There was a statistically significant but small reduction in VAS pain score (mean [95% CI]) on “movement” (40 mm [36 to 45] vs. 47 mm [42 to 51]; difference, −7 mm [−13 to 0]; P = 0.047) at 24 h in the gabapentin (n = 100) compared with control group (n = 97). There was more sedation in the gabapentin group at 24 h (55 vs. 39%, P = 0.026) but greater patient VAS satisfaction (87 vs. 77 mm, P = 0.003).

Conclusions:

A perioperative course of gabapentin produces a clinically insignificant improvement in analgesia after CD and is associated with a higher incidence of sedation.
Cardiac Amyloidosis Presenting With Cardiogenic Shock
Authors: Afzal Ashwad , Brener Sorin J. , Narula Navneet , Worku Berhane , Gulkarov Iosif
Published: June 2015

Cardiac amyloidosis is an infiltrative disorder of the myocardium. It is the result of one of 4 types of amyloidosis: primary systemic (immunoglobulin light chain), secondary, familial (hereditary), or senile. Cardiac amyloidosis ultimately causes congestive heart failure due to irreversible restrictive cardiomyopathy. Because of the rapid progression of the disease, early recognition and determination of underlying etiology are important for tailored therapy. Current interventions range from conservative heart failure management to autologous stem cell and heart transplantation. We present a case of cardiac amyloidosis accompanying undiagnosed multiple myeloma to illustrate the rapid progression of the disease and the complexities of diagnosing and treating this disorder.