bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of quantum Bernoulli noises
Authors: Wang Caishi , Zhang Jihong
Published: October 2013

The family \documentclass[12pt]{minimal}\begin{document}$\lbrace \partial _k, \partial _k^{\ast }\rbrace _{k\ge 0}$\end{document}{∂k,∂k*}k≥0 of annihilation and creation operators acting on square integrable functionals of a Bernoulli process Z = (Zk)k⩾0 can be interpreted as quantum Bernoulli noises. In this note we consider the operator family \documentclass[12pt]{minimal}\begin{document}$\lbrace \ell _k, \ell _k^{\ast }\rbrace _{k\ge 0}$\end{document}{ℓk,ℓk*}k≥0, where \documentclass[12pt]{minimal}\begin{document}$\ell _k=\partial _k\mathbb {E}_k$\end{document}ℓk=∂kEk with \documentclass[12pt]{minimal}\begin{document}$\mathbb {E}_k$\end{document}Ek being the conditional expectation (operator) given σ-field σ(Zj; 0 ⩽ j ⩽ k). We show that ℓk (resp. \documentclass[12pt]{minimal}\begin{document}$\ell _k^{\ast }$\end{document}ℓk*) is essentially a kind of localization of the annihilation operator ∂k (resp. creation operator \documentclass[12pt]{minimal}\begin{document}$\partial _k^{\ast }$\end{document}∂k*). We examine properties of the family \documentclass[12pt]{minimal}\begin{document}$\lbrace \ell _k, \ell _k^{\ast }\rbrace _{k\ge 0}$\end{document}{ℓk,ℓk*}k≥0 and prove, among other things, that ℓk and \documentclass[12pt]{minimal}\begin{document}$\ell _k^{\ast }$\end{document}ℓk* satisfy a local canonical anti-communication relation and \documentclass[12pt]{minimal}\begin{document}$(\ell _k^{\ast })_{k\ge 0}$\end{document}(ℓk*)k≥0 forms a mutually orthogonal operator sequence although each ℓk is not a projection operator. We find that the operator series \documentclass[12pt]{minimal}\begin{document}$\sum _{k=0}^{\infty } \ell _k^{\ast }X\ell _k$\end{document}∑k=0∞ℓk*Xℓk converges in the strong operator topology for each bounded operator X acting on square integrable functionals of Z. In particular we get an explicit sum of the operator series \documentclass[12pt]{minimal}\begin{document}$\sum _{k=0}^{\infty } \ell _k^{\ast }\ell _k$\end{document}∑k=0∞ℓk*ℓk. A useful norm estimate on \documentclass[12pt]{minimal}\begin{document}$\sum _{k=0}^{\infty } \ell _k^{\ast }X\ell _k$\end{document}∑k=0∞ℓk*Xℓk is also obtained. Finally we show applications of our main results to quantum dynamical semigroups and quantum probability.
Direct characterization of nanocrystal size distribution using Raman spectroscopy
Authors: Doğan İlker , van de Sanden Mauritius C. M.
Published: October 2013

We report a rigorous analytical approach based on one-particle phonon confinement model to realize direct detection of nanocrystal size distribution and volume fraction by using Raman spectroscopy. For the analysis, we first project the analytical confinement model onto a generic distribution function, and then use this as a fitting function to extract the required parameters from the Raman spectra, i.e., mean size and skewness, to plot the nanocrystal size distribution. Size distributions for silicon nanocrystals are determined by using the analytical confinement model agree well with the one-particle phonon confinement model, and with the results obtained from electron microscopy and photoluminescence spectroscopy. The approach we propose is generally applicable to all nanocrystal systems, which exhibit size-dependent shifts in the Raman spectrum as a result of phonon confinement.
Tunable optoelectronic and ferroelectric properties in Sc-based III-nitrides
Authors: Zhang Siyuan , Holec David , Fu Wai Yuen , Humphreys Colin J. , Moram Michelle A.
Published: October 2013

Sc-based III-nitride alloys were studied using density functional theory with special quasi-random structure methodology. ScxAl1−xN and ScxGa1−xN alloys are found to be stable in hexagonal phases up to x ≈ 0.56 and x ≈ 0.66, respectively, above which rock-salt structures are more stable. Epitaxial strain stabilization can prevent spinodal decomposition up to x ≈ 0.4 (ScxAl1−xN on AlN or GaN) and x = 0.27 (ScxGa1−xN on GaN). The increase in Sc content expands the in-plane lattice parameter of ScxAl1−xN and ScxGa1−xN alloys, leads to composition- and strain-tunable band gaps and polarization, and ultimately introduces ferroelectric functionality in ScxGa1−xN at x ≈ 0.625. A modified Becke-Johnson exchange-correlation potential was applied to study the electronic structures, which yielded band gaps comparable to those from hybrid functional calculations, yet in a much shorter computational time. The alloys were found to retain wide band gaps, which stay direct up to x = 0.25 (ScxAl1−xN) and x = 0.5 (ScxGa1−xN). The band gaps decrease with increasing x for ScxAl1−xN, in which the Sc-3d states dominate at the conduction band minimum and lead to flat electron dispersion at the Γ point. Conversely, the band gaps increase with increasing x for ScxGa1−xN (up to x = 0.5), in which Sc-3d states do not contribute to the conduction band minimum at the Γ point.
Flux distraction effect on magnetoelectric laminate sensors and gradiometer
Authors: Shen Ying , Gao Junqi , Wang Yaojin , Hasanyan Davresh , Finkel Peter , Li Jiefang , Viehland D.
Published: October 2013

A magnetic flux distraction effect caused by a nearby metallic material was investigated for Metglas/Pb(Mg1/3Nb2/3)O3–PbTiO3 laminated magnetoelectric (ME) sensors. Using flux distraction, a ME sensor can perform an accurate search for metallic targets of different dimensions at various distances. Detection results and simulations were in good agreement. The findings demonstrate an effective means to employ stationary ME sensors and gradiometers for magnetic search applications.
Electrically driven, narrow-linewidth blackbody emission from carbon nanotube microcavity devices
Authors: Fujiwara M. , Tsuya D. , Maki H.
Published: October 2013

We report electrically driven narrow-linewidth blackbody emission from carbon-nanotube with Fabry-Perot microcavities. We fabricated two types of devices with microcavities consisting of either gold mirrors or distributed Bragg reflectors (DBR). Gold-mirror microcavity devices exhibit blackbody emission with narrowed full-width at half-maximum of ∼50 nm in contrast to the broad normal blackbody emission spectrum. The spectra from these devices can be explained by theoretical calculations accounting for the temperature-dependent intrinsic blackbody spectra and transmittance spectrum of the microcavity. Moreover, the DBR microcavity devices show a narrower resonant peak inside the photonic bandgap, compared with the gold-mirror microcavity device.
High-throughput synthesis of thermoelectric Ca3Co4O9 films
Authors: Pravarthana D. , Lebedev O. I. , Hebert S. , Chateigner D. , Salvador P. A. , Prellier W.
Published: October 2013

Properties of complex oxide thin films can be tuned over a range of values as a function of mismatch, composition, orientation, and structure. Here, we report a strategy for growing structured epitaxial thermoelectric thin films leading to improved Seebeck coefficient. Instead of using single-crystal sapphire substrates to support epitaxial growth, Ca3Co4O9 films are deposited, using the Pulsed Laser Deposition technique, onto Al2O3 polycrystalline substrates textured by spark plasma sintering. The structural quality of the 2000 Å thin film was investigated by transmission electron microscopy, while the crystallographic orientation of the grains and the epitaxial relationships were determined by electron backscatter diffraction. The use of a polycrystalline ceramic template leads to structured films that are in good local epitaxial registry. The Seebeck coefficient is about 170 μV/K at 300 K, a typical value of misfit material with low carrier density. This high-throughput process, called combinatorial substrate epitaxy, appears to facilitate the rational tuning of functional oxide films, opening a route to the epitaxial synthesis of high quality complex oxides.
Extended X-ray absorption fine structure spectroscopy of selenium-hyperdoped silicon
Authors: Newman Bonna K. , Ertekin Elif , Sullivan Joseph T. , Winkler Mark T. , Marcus Matthew A. , Fakra Sirine C. , Sher Meng-Ju , Mazur Eric , Grossman Jeffrey C. , Buonassisi Tonio
Published: October 2013

Silicon doped with an atomic percent of chalcogens exhibits strong, uniform sub-bandgap optical absorptance and is of interest for photovoltaic and infrared detector applications. This sub-bandgap absorptance is reduced with subsequent thermal annealing indicative of a diffusion mediated chemical change. However, the precise atomistic origin of absorptance and its deactivation is unclear. Herein, we apply Se K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy to probe the chemical states of selenium dopants in selenium-hyperdoped silicon annealed to varying degrees. We observe a smooth and continuous selenium chemical state change with increased annealing temperature, highly correlated to the decrease in sub-bandgap optical absorptance. In samples exhibiting strong sub-bandgap absorptance, EXAFS analysis reveals that the atoms nearest to the Se atom are Si at distances consistent with length scales in energetically favorable Se substitutional-type point defect complexes as calculated by density functional theory. As the sub-bandgap absorptance increases, EXAFS data indicate an increase in the Se-Si bond distance. In specimens annealed at 1225 K exhibiting minimal sub-bandgap absorptance, fitting of the EXAFS spectra indicates that Se is predominantly in a silicon diselenide (SiSe2) precipitate state. The EXAFS study supports a model of highly optically absorbing point defects that precipitate during annealing into structures with no sub-bandgap absorptance.
Admittance spectroscopy on buried GaSb junctions due to defect distribution in GaAs/GaSb metalorganic vapor phase epitaxy heterostructures
Authors: Baldini M. , Gombia E. , Parisini A. , Ghezzi C. , Gorni M.
Published: October 2013

Admittance spectroscopy was employed to investigate the electrical properties of buried GaSb homojunctions. A strong p-type surface layer was obtained in n-type GaSb bulk crystals through diffusion of Zn atoms. The acceptor impurities were introduced into Te-doped substrates by epitaxially growing a heavily p(Zn)-doped GaAs layer. Current-voltage investigation, after the removal of the GaAs cap layer, demonstrated the formation of the GaSb p-n homojunction. However, the p-n interface of the junctions resulted to be not due to the presence of Zn. In fact, secondary ion mass spectrometry pointed out only a small penetration depth of Zn atoms in the GaSb substrate (∼100 nm), whereas electron beam induced current investigation demonstrated that the p-n junction interface was located more deeply into the substrate (∼1 μm). Admittance spectroscopy and capacitance-voltage investigations led to attribute the change of conduction type from n to p of GaSb beyond the Zn penetration depth to the formation of lattice acceptor defects, influenced by the thermal annealing processes during and after the GaAs growth. An attempt to explain the formation of the buried junction in terms of atomic inter-diffusion is provided, in order to justify, from a microscopic point of view, the low diffusivity of Zn in GaSb, and the depth of the p-n junction interface in the substrate.
Asymmetric structure-induced hot-electron injection under hot-carrier stress in a-InGaZnO thin film transistor
Authors: Tsai Ming-Yen , Chang Ting-Chang , Chu Ann-Kuo , Chen Te-Chih , Hsieh Tien-Yu , Lin Kun-Yao , Tsai Wu-Wei , Chiang Wen-Jen , Yan Jing-Yi
Published: October 2013

This letter investigates the degradation behavior under hot-carrier stress in InGaZnO thin film transistors with I- and U-shaped asymmetric electrodes. After hot-carrier stress, a serious Vt shift, as well as on-current and subthreshold swing degradations are observed in Id-Vg transfer curve under reverse mode. Moreover, it is found that the Vt instability is caused by hot-electron injection near the drain side, and this phenomenon which is verified by C-V measurement. Furthermore, the location of trapped hot-electron is estimated from the two-stage rise in the gate-to-drain/gate-to-source capacitance curves and then verified by the simulation tool.
Measurement of 3D plasma response to external magnetic perturbations in the presence of a rotating external kink
Authors: Shiraki Daisuke , Angelini Sarah M. , Byrne Patrick J. , DeBono Bryan A. , Hughes Paul E. , Levesque Jeffrey P. , Mauel Michael E. , Maurer David A. , Navratil Gerald A. , Peng Qian , Rath Nikolaus , Rhodes Dov J. , Stoafer Christopher C.
Published: October 2013

The detailed measurements of the 3D plasma response to applied external magnetic perturbations in the presence of a rotating external kink are presented, and compared with the predictions of a single-helicity linear model of kink mode dynamics. The modular control coils of the High Beta Tokamak-Extended Pulse (HBT-EP) device are used to apply resonant m/n = 3/1 magnetic perturbations to wall-stabilized tokamak plasmas with a pre-existing rotating 3/1 kink mode. The plasma response is measured in high-resolution with the extensive magnetic diagnostic set of the HBT-EP device. The spatial structures of both the naturally rotating kink mode and the externally driven response are independently measured and observed to be identical, while the temporal dynamics are consistent with the independent evolution and superposition of the two modes. This leads to the observation of a characteristic change in 3D field dynamics as a function of the applied field amplitude. This amplitude dependence is found to be different for poloidal and radial fields. The measured 3D response is compared to and shown to be consistent with the predictions of the linear single-helicity model in the “high-dissipation” regime, as reported previously [M. E. Mauel et al., Nucl. Fusion 45, 285 (2005)].
High-intensity laser-driven proton acceleration enhancement from hydrogen containing ultrathin targets
Authors: Dollar F. , Reed S. A. , Matsuoka T. , Bulanov S. S. , Chvykov V. , Kalintchenko G. , McGuffey C. , Rousseau P. , Thomas A. G. R. , Willingale L. , Yanovsky V. , Litzenberg D. W. , Krushelnick K. , Maksimchuk A.
Published: October 2013

Laser driven proton acceleration experiments from micron and submicron thick targets using high intensity (2 × 1021 W/cm2), high contrast (10−15) laser pulses show an enhancement of maximum energy when hydrogen containing targets were used instead of non-hydrogen containing. In our experiments, using thin (<1μm) plastic foil targets resulted in maximum proton energies that were consistently 20%–100% higher than when equivalent thickness inorganic targets, including Si3N4 and Al, were used. Proton energies up to 20 MeV were measured with a flux of 107 protons/MeV/sr.
Modulation of the properties of thin ferromagnetic films with an externally applied electric field in ferromagnetic/piezoelectric/ferromagnetic hybrids
Authors: Stamopoulos D. , Zeibekis M. , Zhang S. J.
Published: October 2013

In many cases, technological advances are based on artificial low-dimensional structures of heterogeneous constituents, thus called hybrids, that when come together they provide stand-alone entities that exhibit entirely different properties. Such hybrids are nowadays intensively studied since they are attractive for both basic research and oncoming practical applications. Here, we studied hybrids constituted of piezoelectric (PE) and ferromagnetic (FM) components in the form FM/PE/FM, ultimately aiming to provide means for the controlled modulation of the properties of the FM electrodes, originating from the strain imposed to them by the PE mediator when an electric field is applied. The PE component is in single crystal form, 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT), while the FM outer layers are Cobalt (Co) in thin film form. Detailed magnetization measurements performed under variation of the electric field applied to PMN-PT demonstrated the efficient modulation of the properties of the Co electrodes at low temperature (coercive field modulation up to 27% and saturation magnetization absolute modulation up to 4% at T = 10 K for electric field not exceeding 6 kV/cm). The modulation degree faints upon increase of the temperature, evidencing that the thermal energy eventually dominates all other relevant energy scales. Candidate mechanisms are discussed for the explanation of these experimental observations. The results presented here demonstrate that commercially available materials can result in quantitatively noticeable effects. Thus, such elemental Co/PMN-PT/Co units can be used as a solid basis for the development of devices.
Hybrid bio/non-bio interfaces for protein-glucose interaction monitoring
Authors: Caliò Alessandro , Rea Ilaria , Politi Jane , Giardina Paola , Longobardi Sara , Stefano Luca De
Published: October 2013

Amphiphilic proteins, which self-assemble at solid-liquid interface in nanometric biolayer, such as hydrophobins, can be used as multifunctional film to passivate porous silicon dioxide and also sense glucose. Several porous silicon dioxide optical transducers (rugate filter, Thue-Morse sequence, and microcavity) have been protein-modified and tested in monitoring hydrophobins-glucose binding. A simple, easy-to-integrate technique, such as water contact angle, is able to reveal sugar presence at 1.2 mg/ml, whereas spectroscopic reflectometry fails. Fluorescence measurements confirm protein layer-glucose interaction. This proof-of-concept measurement could be the starting point for small analytes porous silicon based optical sensors.
Atom-by-atom simulations of graphene growth by decomposition of SiC (0001): Impact of the substrate steps
Authors: Morita Masato , Norimatsu Wataru , Qian Hu-Jun , Irle Stephan , Kusunoki Michiko
Published: October 2013

The atomic-scale carbon rearrangement into graphene by the thermal decomposition of SiC (0001) was simulated by the density-functional tight-binding technique. By decomposing the terrace of the SiC (0001) surface, the carbon chains formed a three-dimensional structure, because the carbon atoms are released by losing their original contacts to silicon atom. On the other hand, in the step model, the silicon atoms at the step-edge act as trapping sites for the released carbon atoms, and the carbon network effectively nucleated and expanded. After nucleation at the step, graphene can grow by the further decomposition together with retreat of the step.
Phonon-assisted field emission from W18O49 nanowires
Authors: Chen W. Q. , Zhao C. X. , Wu J. Q. , Deng S. Z. , Xu N. S. , Chen Jun
Published: October 2013

Temperature dependence of field emission characteristics of tungsten sub-oxide (W18O49) nanowires was investigated in the range from 143 K to room temperature. It is found that the field emission currents under the same applied electrical field decrease with the decreasing temperature. A two-step process involving the phonon-assisted tunneling from defect states to conduction band was introduced to explain the observed phenomenon. A good agreement between the theoretical and experimental results was achieved.
Impact of Fermi level pinning inside conduction band on electron mobility in InGaAs metal-oxide-semiconductor field-effect transistors
Authors: Taoka Noriyuki , Yokoyama Masafumi , Hyeon Kim Sang , Suzuki Rena , Lee Sunghoon , Iida Ryo , Hoshii Takuya , Jevasuwan Wipakorn , Maeda Tatsuro , Yasuda Tetsuji , Ichikawa Osamu , Fukuhara Noboru , Hata Masahiko , Takenaka Mitsuru , Takagi Shinichi
Published: October 2013

Combining the split capacitance-voltage method with Hall measurements revealed the existence of interface traps within the conduction band (CB) of InGaAs in metal-oxide-semiconductor (MOS) structures with Al2O3 (or HfO2)/InGaAs interfaces. The impact of these interface traps on inversion-layer mobilities in InGaAs MOS field-effect transistors with various interface structures was investigated. We found that the interface traps (>1013 cm−2 eV−1) induce Fermi level pining at an energy level 0.21–0.35 eV above the CB minimum, which degrades the mobilities in the high inversion carrier concentration region. Furthermore, the energy levels are tunable by changing the interface structures.
Molecular design of hole-transporting material for efficient and stable green phosphorescent organic light-emitting diodes
Authors: Fukagawa Hirohiko , Shimizu Takahisa , Kiribayashi Yukihiro , Osada Yoshichika , Kamada Taisuke , Yamamoto Toshihiro , Shimidzu Naoki , Kurita Taiichiro
Published: October 2013

We examined the hole-transporting-material (HTM)-dependent device characteristics of green phosphorescent organic light-emitting diodes (PHOLEDs) using an electron-transporting host. The emission efficiency of the PHOLEDs was proportional to the optical band gap and the triplet energy of the HTMs. On the other hand, the operational stability of the PHOLEDs was not proportional to the emission efficiency. By analyzing the device characteristics in relation to the molecular structure of HTMs, amine derivative with dibenzothiophene was found to be effective HTMs suitable for highly efficient and stable green PHOLEDs.
A compact high temperature superconducting bandpass filter for integration with a Josephson mixer
Authors: Bai D. D. , Du J. , Zhang T. , He Y. S.
Published: October 2013

A compact eight-pole high temperature superconducting (HTS) filter is designed for the RF signal input of an HTS Josephson mixer. The filter has 18.2% fractional bandwidth centered at 11 GHz. A stepped-impedance hairpin resonator is employed to minimize the filter size. The obtained filter size is 10 mm × 2.79 mm, which is very compact. The monolithic HTS Josephson frequency down-converter that incorporated this new filter demonstrated the highest conversion efficiency to date for an HTS Josephson mixer. Both the filter and the on-chip HTS circuit module were fabricated on a 0.5 mm thick MgO wafer with a single-sided YBCO film. The design, simulation, and experimental characterization of the HTS filter are presented in this paper. The early measurement results of the integrated HTS down-converter incorporated this filter are also described.
Ultra-high sensitive and high resolution optical coherence tomography using a laser induced electromagnetic dipole
Authors: Kuroda Hiroto , Baba Motoyoshi , Suzuki Masayuki , Yoneya Shin
Published: October 2013

Utilizing an optical coherence tomography measurement, we have developed a technique that actively uses a dielectric response due to an induced dipole moment caused by a mode-locked pulsed laser light source. Irradiated laser light in the material induces a photo-induced electric dipole resulting in a refractive index change for its strong electric field. Using this technique, we obtained a highly sensitive fundus retina tomogram of a human eye in vivo with a resolution of 1.3 μm by single scanning for 20 ms using 8 fs mode-locked pulse laser light with a 350 nm spread spectrum.
Electrostatic forces on two almost touching nonspherical charged conductors
Authors: Khair Aditya S.
Published: October 2013

Analytical expressions are derived for the electrostatic forces on two almost touching nonspherical conductors held at unequal voltages or carrying dissimilar charges in an insulating medium. Each conductor is a body of revolution whose surface is defined by the equation rn+zn=an, where r and z are radial and axial cylindrical co-ordinates, respectively, 2a is the equatorial width, and n is a parameter that controls the particle shape. The two objects are of identical shape and placed in a coaxial configuration, in which case the electrostatic forces are solely along their line of centers. The calculation of the forces is performed via a local analysis of the electrostatics in the thin gap region separating the particles. At a fixed potential difference, the magnitude of the attractive force F on the particles scales with the minimum gap height h0 as F∼h02(1/n−1) for n > 1 and F∼ln h0 for n = 1, to leading order as h0/a→0. The force increases as the gap region becomes flatter (increasing n), due to the intense electric field in the gap acting over a larger surface area. The opposite is found for particles carrying fixed charges: here, F∼h0−2/n for n > 2 and F∼h0−1[ln(a/h0)]−2 for n = 2. In this case, the potential difference between the conductors diminishes as the gap region becomes flatter, which overpowers the increase in gap area. Our results demonstrate that like-charge attraction occurs for a broad class of nonspherical conductors at close separations. The predicted sensitivity of the electrostatic force to particle shape is relevant to probe-based microscopy: specifically, to quantify the influence of tip-geometry on the force experienced by a charged probe near a conducting surface.
Enhanced localized surface plasmon resonance obtained in two step etched silicon nanowires decorated with silver nanoparticles
Authors: Mulazimoglu Emre , Nogay Gizem , Turan Rasit , Emrah Unalan Husnu
Published: October 2013

We report on localized surface plasmon resonance (LSPR) of silicon nanowires decorated with silver nanoparticles. Hydrogen peroxide in metal-assisted-etching method degenerates the surface of nanowires and creates oxygen-related defect sites. These defect sites enhance the infrared absorption at higher frequencies and emit visible light by band-to-band radiative recombination. Moreover, an almost 50-fold enhanced LSPR was obtained for 24 nm thick silver deposited 5 μm long silicon nanowires. This enhancement was attributed to the change in the dielectric constant of effective medium created by defect states. LSPR wavelength could be tuned by changing the silver particle size and nanowire length.
Frictional properties of native and functionalized type I collagen thin films
Authors: Chung Koo-Hyun , Chen Antony K. , Anderton Christopher R. , Bhadriraju Kiran , Plant Anne L. , Bush Brian G. , Cook Robert F. , DelRio Frank W.
Published: October 2013

Frictional properties of native and fibronectin (FN)-functionalized type I collagen (COL) thin films were studied via atomic force microscopy. The COL lateral contact stiffness was dependent only on the hydration state, indicating that shear deformation was invariant with FN. In contrast, the COL coefficient of friction and shear strength varied with both functionalization and hydration state. The changes in shear strength were found to correlate well with changes in mean cell spread area on the same thin films, suggesting that shear strength is a better indicator of cell spreading than heretofore considerations of film, and thus extracellular matrix, stiffness alone.
Thermal conductivity of ZnTe nanowires
Authors: Davami Keivan , Weathers Annie , Kheirabi Nazli , Mortazavi Bohayra , Pettes Michael T. , Shi Li , Lee Jeong-Soo , Meyyappan M.
Published: October 2013

The thermal conductivity of individual ZnTe nanowires (NWs) was measured using a suspended micro-bridge device with built-in resistance thermometers. A collection of NWs with different diameters were measured, and strong size-dependent thermal conductivity was observed in these NWs. Compared to bulk ZnTe, NWs with diameters of 280 and 107 nm showed approximately three and ten times reduction in thermal conductivity, respectively. Such a reduction can be attributed to phonon-surface scattering. The contact thermal resistance and the intrinsic thermal conductivities of the nanowires were obtained through a combination of experiments and molecular dynamic simulations. The obtained thermal conductivities agree well with theoretical predictions.
Optical switching at 1.55 μm in silicon racetrack resonators using phase change materials
Authors: Rudé Miquel , Pello Josselin , Simpson Robert E. , Osmond Johann , Roelkens Gunther , van der Tol Jos J. G. M. , Pruneri Valerio
Published: October 2013

An optical switch operating at a wavelength of 1.55 μm and showing a 12 dB modulation depth is introduced. The device is implemented in a silicon racetrack resonator using an overcladding layer of the phase change data storage material Ge2Sb2Te5, which exhibits high contrast in its optical properties upon transitions between its crystalline and amorphous structural phases. These transitions are triggered using a pulsed laser diode at λ = 975 nm and used to tune the resonant frequency of the resonator and the resultant modulation depth of the 1.55 μm transmitted light.
Ring formation from a drying sessile colloidal droplet
Authors: Zhang Wenbin , Yu Tongxu , Liao Longguang , Cao Zexian
Published: October 2013

Ring formation from drying sessile colloidal droplets (∼1.0 mm in size) containing microparticles of silicon or polystyrene was investigated with video microscopy. Results show that ring formation begins at the pinned contact line with the growth of an annular nucleus in a line by line way, which recedes inward albeit only slightly, followed by stacking of particles when the flow velocity becomes sufficiently large. The central height of the droplet decreases linearly with evaporation time, which implies that in the early stage, the number of particles arriving at contact line increases with time in a power law N∝t3/(1 + λ), where the parameter λ, according to Deegan's evaporation model, is related to the contact angle via $\lambda = \frac{{\pi - 2\theta _c }}{{2\pi - 2\theta _c }}$λ=π−2θc2π−2θc. Experimental values of λ agree well with model calculation for small contact angles, but are relatively smaller in the case of large contact angles. ‘Amorphization’ mechanism for the deposit at different stages of evaporation is discussed. Marangoni flow in a droplet on heated substrate introduces a desorption path for particles along the liquid surface, which can partially resolve the ring. Residual particles floating on the liquid surface may leave behind a homogeneous monolayer coating inside the dried spot. A “jump” in the droplet surface area at later stage of evaporation seems inevitably to cause a depletion zone of particles next to the ring. These results may be helpful for the development of strategies towards suppression of coffee ring effect and/or obtaining homogeneous coatings from drying colloidal suspension.
In-Situ Alloying Dynamics and Phase Morphology of Binary Polymer Blends
Authors: Li Jing-qing , Ma Gui-qiu , Yuan Xu-bo , Sheng Jing
Published: October 2013

In-situ alloying of polypropylene (PP)/polystyrene (PS) binary polymer blends using anhydrous aluminum chloride as a catalyst was investigated by small angle light scattering. The phase structures, morphology, and compatibilization effect in the obtained alloys during the in-situ alloying process were investigated by Rayleigh scattering. The content of compatible domains between the two phases of PP and PS in the in-situ alloys, i.e. the volume fraction of the interfacial transition layer, and the ‘invariant’ of the alloys were first calculated to describe the in-situ alloying dynamics, which reveals that the resulting in-situ PP/PS alloys are partially compatible. The relationship between the volume fraction of the interfacial transition layer or ‘invariant’ and the in-situ alloying reactive conditions are discussed in detail. The phase structural parameters, including correlation distance and average chord lengths, were calculated to characterize the phase size evolutions of the in-situ alloys, confirming the validity of using the volume fraction of the interfacial transition layer or ‘invariant’ to investigate the in-situ alloying dynamics.
Do High Food Prices Increase Food Insecurity in the United States?
Authors: Gregory Christian A. , Coleman‐Jensen Alisha
Published: October 2013

While research establishing the link between high food prices and increased food insecurity in developing countries is robust, similar research about the United States has been lacking. This has been due in part to a lack of suitable price data, but it has also been due to the assumption that prices matter less in the United States, where households spend a relatively small fraction of their income on food. In this article we examine the role that local food prices play in determining food insecurity in the United States by using newly‐developed price data. We examine whether low‐income households participating in the Supplemental Nutrition Assistance Program (SNAP, formerly Food Stamps) are more likely to be food insecure in areas where food prices are higher. We find that the average effect of food prices on the probability of food insecurity is positive and significant: a one‐standard deviation increase in food prices is associated with increases of 2.7, 2.6, and 3.1 percentage points in household, adult, and child food insecurity, respectively. These marginal effects amount to 5.0%, 5.1%, and 12.4% increases in the prevalence of food insecurity for SNAP households, adults, and children, respectively. These results suggest that indexing SNAP benefits to local food prices could improve the ability of the program to reduce food insecurity and economic hardship more generally in areas with high food prices.
A wavelet-based method to exploit epigenomic language in the regulatory region
Authors: Nguyen Nha , Vo An , Won Kyoung-Jae
Published: October 2013

Motivation: Epigenetic landscapes in the regulatory regions reflect binding condition of transcription factors and their co-factors. Identifying epigenetic condition and its variation is important in understanding condition-specific gene regulation. Computational approaches to explore complex multi-dimensional landscapes are needed.

Results: To study epigenomic condition for gene regulation, we developed a method, AWNFR, to classify epigenomic landscapes based on the detected epigenomic landscapes. Assuming mixture of Gaussians for a nucleosome, the proposed method captures the shape of histone modification and identifies potential regulatory regions in the wavelet domain. For accuracy estimation as well as enhanced computational speed, we developed a novel algorithm based on down-sampling operation and footprint in wavelet. We showed the algorithmic advantages of AWNFR using the simulated data. AWNFR identified regulatory regions more effectively and accurately than the previous approaches with the epigenome data in mouse embryonic stem cells and human lung fibroblast cells (IMR90). Based on the detected epigenomic landscapes, AWNFR classified epigenomic status and studied epigenomic codes. We studied co-occurring histone marks and showed that AWNFR captures the epigenomic variation across time.

Availability and implementation: The source code and supplemental document of AWNFR are available at http://wonk.med.upenn.edu/AWNFR.

Contact:  wonk@mail.med.upenn.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Evaluating Sensitivity of Parameters of Interest to Measurement Invariance in Latent Variable Models
Authors: Oberski Daniel L.
Published: October 2013

Latent variable models can only be compared across groups when these groups exhibit measurement equivalence or “invariance,” since otherwise substantive differences may be confounded with measurement differences. This article suggests examining directly whether measurement differences present could confound substantive analyses, by examining the expected parameter change (EPC)-interest. The EPC-interest approximates the change in parameters of interest that can be expected when freeing cross-group invariance restrictions. Monte Carlo simulations suggest that the EPC-interest approximates these changes well. Three empirical applications show that the EPC-interest can help avoid two undesirable situations: first, it can prevent unnecessarily concluding that groups are incomparable, and second, it alerts the user when comparisons of interest may still be invalidated even when the invariance model appears to fit the data. R code and data for the examples discussed in this article are provided in the electronic appendix (http://hdl.handle.net/1902.1/21816).
Pseudoalteromonas xiamenensis sp. nov., a marine bacterium isolated from coastal surface seawater
Authors: Zhao Chang-Hui , Luo Jing-Jing , Gong Ting , Huang Xiang-Ling , Ye De-Zan , Luo Zhu-Hua
Published: October 2013

A Gram-negative, oxidase- and catalase-positive, rod-shaped, non-spore-forming, motile, aerobic bacterium, designated Y2T, was isolated from surface seawater of Yundang Lake, Xiamen, China. The strain was able to grow in the presence of 0.5–6.0 % NaCl (optimum 1.0–1.5 %), at pH 5–10 (optimum pH 8) and at 10–40 °C (optimum 25 °C). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain Y2T belongs to the genus

Pseudoalteromonas

, with the highest sequence similarity of 94.9 % to

Pseudoalteromonas tunicata

D2T; within the genus

Pseudoalteromonas

, it showed the lowest similarity of 92.8 % to

Pseudoalteromonas denitrificans

ATCC 43337T. The G+C content of the chromosomal DNA of strain Y2T was 45.1 mol%. The predominant fatty acids were summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), C16 : 0, C12 : 0 3-OH and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The only respiratory quinone detected was Q-8. Based on the phylogenetic and phenotypic characteristics, strain Y2T represents a novel species of the genus

Pseudoalteromonas

, for which the name Pseudoalteromonas xiamenensis sp. nov. is proposed; the type strain is Y2T ( = CGMCC 1.12157T = JCM 18779T).
Flavobacterium spartansii sp. nov., a pathogen of fishes, and emended descriptions of Flavobacterium aquidurense and Flavobacterium araucananum
Authors: Loch Thomas P. , Faisal Mohamed
Published: October 2013

Two strains (T16T and S12) of a Gram-reaction-negative, rod-shaped, yellow-pigmented bacterium were recovered from kidneys of feral spawning adult Chinook salmon (Oncorhynchus tshawytscha) and the gills of captive-reared Chinook salmon fingerlings suffering a mortality episode, respectively. Polyphasic characterization revealed that these strains possessed gliding motility, contained a flexirubin-type pigment, proteolysed multiple substrates (i.e. gelatin, casein and elastin), and had a mean DNA G+C content of 35.6 mol%. Sequencing of the 16S rRNA gene demonstrated that strains T16T and S12 were nearly identical to one another (>99 % similarity) and were placed within the genus

Flavobacterium

, with

Flavobacterium aquidurense

CCUG 59847T (98.3 %),

Flavobaterium araucananum

CCUG 61031T (98.2 %) and

Flavobacterium frigidimaris

(AB183888, 98.1 %) being their closest relatives. Subsequent phylogenetic analyses using neighbour-joining, maximum-parsimony and Bayesian methodologies demonstrated that strains T16T and S12 formed a well-supported clade within the genus

Flavobacterium

that was distinct from other

Flavobacterium

species. The major fatty acid constituents of strains T16T and S12 were iso-C15 : 0, C16 : 1ω6c and/or C16 : 1ω7c, iso-C17 : 0 3-OH, and iso-C15 : 0 3-OH according to fatty acid methyl ester analysis. The mean level of DNA–DNA relatedness between strain T16T and

F. aquidurense

CCUG 59847T and

F. araucananum

CCUG 61031T was 23 and 29 %, respectively. Thus, the data accumulated in this study support the suggestion that strains T16T and S12 represent a novel species of the genus

Flavobacterium

, for which the name Flavobacterium spartansii sp. nov. is proposed. The type strain is T16T ( = LMG 27337T = ATCC BAA-2541T). Emended descriptions of

F. aquidurense

and

F. araucananum

are also proposed.
Terriglobus
tenax sp. nov., an exopolysaccharide-producing acidobacterium isolated from rhizosphere soil of a medicinal plant
Authors: Whang Kyung-Sook , Lee Jae-Chan , Lee Hae-Ran , Han Song-Ih , Chung Sang-Ho
Published: October 2013

An exopolysaccharide-producing bacterium, designated strain DRP 35T, was isolated from the rhizosphere soil of a medicinal herb, Angelica sinensis, at Geumsan in Korea. Cells were Gram-staining-negative, non-motile, catalase-positive and oxidase-negative short rods. The isolate grew aerobically from 15 to 45 °C (optimum 30 °C), pH 3.5–7.0 (optimum pH 5.0) and in the presence of 0–1.0 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain DRP 35T belongs to the genus

Terriglobus

in the phylum

Acidobacteria

with a sequence similarity of 97.2 % and 97.0 % to

Terriglobus saanensis

SP1PR4T and

Terriglobus roseus

KBS63T, respectively. The genomic DNA G+C content was 62.1 mol%. DNA–DNA relatedness between strain DRP 35T and the type strains of the other species of the genus

Terriglobus

,

T. saanensis

SP1PR4T and

T. roseus

KBS63T, were 24.6 and 17.2 %, respectively. The predominant menaquinone was MK-8. Major fatty acids were iso-C15 : 0, C16 : 1ω7c and C16 : 0. The polar lipids were phosphatidylethanolamine, unidentified aminophospholipid and unknown phospholipids. On the basis of polyphasic analysis from this study, strain DRP 35T represents a novel species of the genus

Terriglobus

for which the name Terriglobus
tenax sp. nov. is proposed. The type strain is DRP 35T ( = KACC 16474T = NBRC 109677T).
Wenyingzhuangia marina gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from a recirculating mariculture system
Authors: Liu Ying , Liu Liang-Zi , Liu Hong-Can , Zhou Yu-Guang , Qi Fang-Jun , Liu Zhi-Pei
Published: October 2013

A Gram-stain-negative, strictly aerobic and heterotrophic bacterial strain, designed strain D1T, was isolated from a recirculating mariculture system in Tianjin, China. Its taxonomic position was determined using a polyphasic approach. Cells of strain D1T were non-flagellated short rods, 0.3–0.5 µm wide and 0.5–1.0 µm long. Growth was observed at 15–30 °C (optimum, 25 °C), at pH 5.5–9.0 (optimum, pH 6.5–7.0) and in the presence of 1–8 % (w/v) NaCl (optimum, 2–3 %). Cells contained carotenoid pigments but not flexirubin-type pigments. Strain D1T contained MK-6 as the sole menaquinone and phosphatidylethanolamine (PE) as the sole phospholipid and four unidentified lipids. The major cellular fatty acids (>10 %) were iso-C15 : 0 (23.2 %), iso-C17 : 0 3-OH (15.2 %), C16 : 1ω7c/C16 : 1ω6c (14.3 %), iso-C15 : 0 3-OH (13.5 %) and iso-C15 : 1 G (10.8 %). 16S rRNA gene sequence analyses indicated that strain D1T belonged to the family

Flavobacteriaceae

and showed closest phylogenetic relationship to the genus

Lutibacter

, with highest sequence similarity to

Lutibacter aestuarii

MA-My1T (92.2 %). The DNA G+C content of strain D1T was 35.9 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain D1T was considered to represent a novel species in a new genus of the family

Flavobacteriaceae

, for which the name Wenyingzhuangia marina gen. nov., sp. nov. is proposed. The type strain of the type species is D1T ( = CGMCC 1.12162T = JCM 18494T).
Photobacterium
aquae sp. nov., isolated from a recirculating mariculture system
Authors: Liu Ying , Liu Liang-Zi , Song Lei , Zhou Yu-Guang , Qi Fang-Jun , Liu Zhi-Pei
Published: October 2013

A Gram-staining-negative, heterotrophic, facultatively anaerobic bacterium, designated AE6T, was isolated from a grouper (Epinephelus malabaricas) culture tank in a recirculating mariculture system located in Tianjin, China. Strain AE6T was able to grow at 15–40 °C (optimum, 30–35 °C), at pH 5.5–10.0 (optimum, pH 7.0–7.5) and in the presence of 0.5–7 % (w/v) NaCl (optimum, 2–3 %). It contained Q-8 as the predominant respiratory quinone, phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) as the major polar lipids and C16 : 1ω7c/C16 : 1ω6c (40.4 %), C18 : 1ω7c (15.5 %) and C16 : 0 (13.5 %) as the predominant cellular fatty acids. The genomic DNA G+C content was 47.1 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain AE6T belonged to the genus

Photobacterium

(94.2–96.8 % of 16S rRNA gene sequence similarity) and formed a distinct phylogenetic lineage within the genus and exhibited the highest sequence similarity to

Photobacterium aphoticum

CECT 7614T (96.8 %). Multilocus sequence analysis (MLSA) using four loci (gyrB, rpoA, pyrH and recA) also revealed that strain AE6T was phylogenetically related to the genus

Photobacterium

. Based on the phylogenetic, chemotaxonomic and phenotypic evidence, strain AE6T is considered to represent a novel species of the genus

Photobacterium

, for which the name

Photobacterium

aquae sp. nov. is proposed. The type strain is AE6T ( = CGMCC 1.12159T = JCM 18480T).
How Do Hospitals Cope with Sustained Slow Growth in Medicare Prices?
Authors: White Chapin , Wu Vivian Yaling
Published: October 2013

Objective

To estimate the effects of changes in Medicare inpatient hospital prices on hospitals' overall revenues, operating expenses, profits, assets, and staffing.

Primary Data Source

Medicare hospital cost reports (1996–2009).

Study Design

For each hospital, we quantify the year‐to‐year price impacts from changes in the Medicare payment formula. We use cumulative simulated price impacts as instruments for Medicare inpatient revenues. We use a series of two‐stage least squares panel data regressions to estimate the effects of changes in Medicare revenues among all hospitals, and separately among not‐for‐profit versus for‐profit hospitals, and among hospitals experiencing real price increases (“gainers”) versus decreases (“losers”).

Principal Findings

Medicare price cuts are associated with reductions in overall revenues even larger than the direct Medicare price effect, consistent with price spillovers. Among not‐for‐profit hospitals, revenue reductions are fully offset by reductions in operating expenses, and profits are unchanged. Among for‐profit hospitals, revenue reductions decrease profits one‐for‐one. Responses of gainers and losers are roughly symmetrical.

Conclusions

On average, hospitals do not appear to make up for Medicare cuts by “cost shifting,” but by adjusting their operating expenses over the long run. The Medicare price cuts in the Affordable Care Act will “bend the curve,” that is, significantly slow the growth in hospitals' total revenues and operating expenses.
Structure and function of voltage‐gated sodium channels at atomic resolution
Authors: Catterall William A.
Published: October 2013

New Findings

What is the topic of this review?

The central goal of the research reviewed here is to understand the functional properties of voltage‐gated sodium channels at the level of high‐resolution structure of the channel protein.

What advances does it highlight?

The key functional properties of voltage‐gated sodium channels, including voltage‐dependent activation. Sodium conductance and selectivity, block by local anesthetics and related drugs, and both fast and slow inactivation, are now understood at the level of protein structure with high resolution. These emerging high‐resolution structural models may lead to development of safer and more efficacious drugs for treatment of epilepsy, chronic pain, and cardiac arrhythmia through structure‐based drug design.

Voltage‐gated sodium channels initiate action potentials in nerve, muscle and other excitable cells. Early physiological studies described sodium selectivity, voltage‐dependent activation and fast inactivation, and developed conceptual models for sodium channel function. This review article follows the topics of my 2013 Sharpey‐Schafer Prize Lecture and gives an overview of research using a combination of biochemical, molecular biological, physiological and structural biological approaches that have elucidated the structure and function of sodium channels at the atomic level. Structural models for voltage‐dependent activation, sodium selectivity and conductance, drug block and both fast and slow inactivation are discussed. A perspective for the future envisions new advances in understanding the structural basis for sodium channel function and the opportunity for structure‐based discovery of novel therapeutics.