bluuebunny/crossref_metadata_2025 huggingface dataset:
Resources and Pilot Results for Establishing a Mongolian Twin Register
Authors: Gombojav Bayasgalan , Damdinbazar Otgonbayar , Danshiitsoodol Narandalai , Dagvasumberel Gonchigsuren , Purevdorj Erkhembulgan , Gombojav Enkhtsetseg , Chuluunbaatar Urjinbadam , Ochir Chimedsuren , Ichinkhorloo Purevdorj , Sung Joohon
Published: December 2012

Despite the need to provide evidence-based health policy, most developing countries suffer from a lack of resources for sound epidemiologic evidence. Most twin registers have been established in developed countries and there are relatively fewer twin registers in developing countries. Considering the immense potential of twin research, it will be worthwhile to attempt to establish a new twin register in Mongolia, where biomedical studies are still scarce. Our objectives were to initiate the process of establishing a nation-wide twin register in Mongolia, based on a nation-wide, population-based database. With the approval and support of the Ministry of Population Development and Social Welfare of Mongolia, we were able to access an initial list of 411 twin pairs who live in the district of Ulaanbaatar, the capital city of Mongolia. By developing a questionnaire to estimate zygosity, we conducted a pilot survey. Those who registered consisted of 822 individuals or 411 twin pairs (same sex: male — 178; female — 157; different sex — 76), two sets of triplets (same sex: female — 2). The age of twins ranged from 1 to 81 (mean age 7.3 ± 11.3), and 52.4% were males. The first twin survey in Mongolia not only resulted in interim data for the Mongolian Twin Register, but has the potential for establishing a larger register by using the national database. It has been proven possible to establish a twin register for research purposes in Mongolia.
Marine ice deformation experiments: an empirical validation of creep parameters
Authors: Dierckx Marie , Tison Jean‐Louis
Published: December 2012

Marine ice is increasingly recognized as an important component of ice shelves in Antarctica. Because it mainly accretes in “weak” locations, it plays a crucial role in ice shelf stability. Little is known however on the rheology of this particular material (low salinity, no bubbles, specific fabrics). We present marine ice deformation experiments in unconfined uniaxial compression at −10 °C, −6 °C, and −3 °C. Generally, marine ice samples confirm the value of n = 3 for Glen's power law. It also appears to behave systematically “harder” than artificial or meteoric isotropic ice samples used in the past, in the studied stress condition. Bulk salinity does not seem to have a significant impact on the viscosity. All deformation curves compare well with a generalized empirical temperature/viscosity relationship. They represent the first experimental validation of the lower boundary of this rheological relationship recommended for use in modeling ice dynamics.
A simple dynamical model for gravity drainage of brine from growing sea ice
Authors: Rees Jones David W. , Worster M. Grae
Published: December 2012

Gravity drainage of brine through liquid brine channels is the dominant mechanism for the desalination of growing sea ice. We describe and determine mathematically the essential physics of this process, elucidating the connection between downward flow in brine channels and a convective upward flow in the rest of the porous ice, which we show has a vertically linear structure and strength proportional to a Rayleigh number. Our simple dynamical model of this process is used to interpret the exponential propagation of dye fronts in laboratory experiments. We propose that using our new, derived parameterization for gravity drainage in sea ice in terms of two unknown parameters could lead to computationally feasible improvements to thermodynamic sea‐ice models.
Properties of linear contrails in the Northern Hemisphere derived from 2006 Aqua MODIS observations
Authors: Bedka Sarah T. , Minnis Patrick , Duda David P. , Chee Thad L. , Palikonda Rabindra
Published: December 2012

Understanding the role of contrails in the Earth's radiation budget requires an accurate characterization of their macrophysical and microphysical properties, such as cloud top temperature, optical depth, and effective particle size. These properties are derived from 2006 MODerate‐resolution Imaging Spectroradiometer data over the Northern Hemisphere using a bi‐spectral, infrared‐only retrieval technique. Contrail temperature is estimated using a quadratic relationship of flight track pressure with latitude. The results reveal distinct seasonal trends in contrail microphysical properties, with slightly greater mean optical depths and slightly smaller particle sizes during summer. The average contrail optical depth and particle effective diameter are 0.216 and 35.7 µm, respectively. Although fewer contrails occurred at night, there are no appreciable diurnal differences in their retrieved properties. These results should help to fill the gap in our knowledge of contrail properties and will be valuable for model validation.
The ozone response to ENSO in Aura satellite measurements and a chemistry‐climate simulation
Authors: Oman Luke D. , Douglass Anne R. , Ziemke Jerry R. , Rodriguez Jose M. , Waugh Darryn W. , Nielsen J. Eric
Published: December 2012

The El Niño–Southern Oscillation (ENSO) is the dominant mode of inter‐annual variability in the tropical ocean and troposphere. Its impact on tropospheric circulation causes significant changes to the distribution of ozone. Here we derive the lower tropospheric to lower stratospheric ozone response to ENSO from observations by the Tropospheric Emission Spectrometer (TES) and the Microwave Limb Sounder (MLS) instruments, both on the Aura satellite, and compare to the simulated response from the Goddard Earth Observing System Chemistry‐Climate Model (GEOSCCM). Measurement ozone sensitivity is derived using multiple linear regression to include variations from ENSO as well as from the first two empirical orthogonal functions of the quasi‐biennial oscillation. Both measurements and simulation show features such as the negative ozone sensitivity to ENSO over the tropospheric tropical Pacific and positive ozone sensitivity over Indonesia and the Indian Ocean region. Ozone sensitivity to ENSO is generally positive over the midlatitude lower stratosphere, with greater sensitivity in the Northern Hemisphere. GEOSCCM reproduces both the overall pattern and magnitude of the ozone response to ENSO obtained from observations. We demonstrate the combined use of ozone measurements from MLS and TES to quantify the lower atmospheric ozone response to ENSO and suggest its possible usefulness in evaluating chemistry‐climate models.
Climate and climate change in a radiative‐convective equilibrium version of ECHAM6
Authors: Popke D. , Stevens B. , Voigt A.
Published: December 2012

Key Points

ECHAM6 is configured to run in RCE with a mixed‐layer ocean

RCE similar to tropics in mean vertical structure and overturning circulation

Lower climate sensitivity in RCE than in full GCM although feedbacks are present
On the separate effects of soil and land cover on Mediterranean ecohydrology: Two contrasting case studies in Sardinia, Italy
Authors: Montaldo Nicola , Corona Roberto , Albertson John D.
Published: December 2012

Key Points

Comparison of evapotraspiration observations at 2 Mediterranean ecosystems

CO2 and water use efficiency at two competitive ecosystems

Investigate the role of the vegetation type on ET and CO2 exchange dynamics
Cellular promiscuity: explaining cellular fidelity in vivo against unrestrained pluripotency in vitro
Authors: Schatten Gerald
Published: December 2012

The differentiation of pluripotent stem cells into various progeny is perplexing. In vivo, nature imposes strict fate constraints. In vitro, PSCs differentiate into almost any phenotype. Might the concept of ‘cellular promiscuity’ explain these surprising behaviours?
Rapid Quantitative CBF and CMRO2 Measurements from a Single PET Scan with Sequential Administration of Dual 15O-Labeled Tracers
Authors: Kudomi Nobuyuki , Hirano Yoshiyuki , Koshino Kazuhiro , Hayashi Takuya , Watabe Hiroshi , Fukushima Kazuhito , Moriwaki Hiroshi , Teramoto Noboru , Iihara Koji , Iida Hidehiro
Published: December 2012

Positron emission tomography ( PET) with 15O tracers provides essential information in patients with cerebral vascular disorders, such as cerebral blood flow ( CBF), oxygen extraction fraction ( OEF), and metabolic rate of oxygen ( CMRO2). However, most of techniques require an additional C15O scan for compensating cerebral blood volume ( CBV). We aimed to establish a technique to calculate all functional images only from a single dynamic PET scan, without losing accuracy or statistical certainties. The technique was an extension of previous dual-tracer autoradiography (DARG) approach, but based on the basis function method (DBFM), thus estimating all functional parametric images from a single session of dynamic scan acquired during the sequential administration of H215O and 15O2. Validity was tested on six monkeys by comparing global OEF by PET with those by arteriovenous blood sampling, and tested feasibility on young healthy subjects. The mean DBFM-derived global OEF was 0.57 ± 0.06 in monkeys, in an agreement with that by the arteriovenous method (0.54 ± 0.06). Image quality was similar and no significant differences were seen from DARG; 3.57% ± 6.44% and 3.84% ± 3.42% for CBF, and −2.79% ± 11.2% and −6.68% ± 10.5% for CMRO2. A simulation study demonstrated similar error propagation between DBFM and DARG. The DBFM method enables accurate assessment of CBF and CMRO2 without additional CBV scan within significantly shortened examination period, in clinical settings.
Pathogenic mutations causing LBSL affect mitochondrial aspartyl-tRNA synthetase in diverse ways
Authors: van Berge Laura , Kevenaar Josta , Polder Emiel , Gaudry Agnès , Florentz Catherine , Sissler Marie , van der Knaap Marjo S. , Scheper Gert C.
Published: December 2012

The autosomal recessive white matter disorder LBSL (leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation) is caused by mutations in DARS2, coding for mtAspRS (mitochondrial aspartyl-tRNA synthetase). Generally, patients are compound heterozygous for mutations in DARS2. Many different mutations have been identified in patients, including several missense mutations. In the present study, we have examined the effects of missense mutations found in LBSL patients on the expression, enzyme activity, localization and dimerization of mtAspRS, which is important for understanding the cellular defect underlying the pathogenesis of the disease. Nine different missense mutations were analysed and were shown to have various effects on mtAspRS properties. Several mutations have a direct effect on the catalytic activity of the enzyme; others have an effect on protein expression or dimerization. Most mutations have a clear impact on at least one of the properties of mtAspRS studied, probably resulting in a small contribution of the missense variants to the mitochondrial aspartylation activity in the cell.
Psychometric Evaluation of Visual Analog Scale for the Assessment of Chronic Tinnitus
Authors: Adamchic Ilya , Langguth Berthold , Hauptmann Christian , Alexander Tass Peter
Published: December 2012

Purpose

The development of therapeutic interventions for chronic tinnitus requires sensitive and clinically responsive tools to measure treatment-induced changes in tinnitus loudness and annoyance. In this study, the authors evaluated the psychometric properties of patient-reported visual analog scales (VAS) for measuring subjectively perceived tinnitus loudness and annoyance.

Method

The authors analyzed data from a single-blind, randomized, placebo-controlled study of acoustic coordinated reset (CR) neuromodulation in patients with chronic tinnitus (trial registration: “Randomized Evaluation of Sound Evoked Treatment of Tinnitus [RESET] study”; ClinicalTrials.gov identifier: NCT00927121) to assess the reliability, validity, and minimally clinically identifiable difference (MCID) of the VAS loudness and VAS annoyance. The VAS loudness and VAS annoyance were completed at screening, at baseline, and at 5 visits during the 16 weeks of the clinical study. Data were analyzed with respect to test–retest reliability, validity, and MCID.

Results

VAS loudness and VAS annoyance showed good test-retest reliability of .8 and .79, respectively. In terms of convergent validity, VAS loudness and VAS annoyance correlated well with the tinnitus questionnaire at all clinical visits (max
r
= .67,
p
< .05). MCID estimates clustered between 10 and 15 points.

Conclusion

VAS loudness and VAS annoyance are valid and effective measurements for capturing reductions in tinnitus severity in patients with chronic tinnitus.
Stimuli and Normative Data for Detection of Ling-6 Sounds in Hearing Level
Authors: Scollie Susan , Glista Danielle , Tenhaaf Julianne , Dunn Andrea , Malandrino April , Keene Kelley , Folkeard Paula
Published: December 2012

Purpose

The purpose of this work was to develop and evaluate a calibrated version of the Ling-6 sounds for evaluation of aided detection thresholds. Stimuli were recorded, and data from calibration values in dB HL were developed. Aided performance was characterized in adults and children.

Method

Stimuli were recorded, prepared, and transferred to a CD for testing. Initial testing was completed on 29 normally hearing young adults to determine typical responses in dB SPL and reliability. Corrections to dB HL were determined for each stimulus. Twenty-seven adults and 5 children with hearing losses were tested.

Results

Average normal sound field thresholds were 1 dB HL. Aided thresholds for adults varied with unaided hearing level and were better for low-frequency sounds. Adults and children performed differently, possibly because of greater hearing aid gain for children.

Conclusions

Stimulus preparation and shaping resulted in a recorded, calibrated set of Ling-6 stimuli that provide flat normal thresholds in hearing level for normally hearing listeners. Typical performance ranges may vary with hearing level and prescription. More data are required to fully characterize this trend in the pediatric population.
Cosmetic Tattooing of Free Flaps following Head and Neck Reconstruction
Authors: Batstone Martin D. , Fox Carly M. , Dingley Mary E. , Cornelius C. Peter
Published: December 2012

Free flap reconstruction of the head and neck is a widespread procedure. The aesthetic outcome is frequently compromised by color mismatch between the donor site skin and the complex pigmentation of the face. Various surgical procedures have been described to improve the appearance of external skin paddles. Medical tattooing is commonly used for nipple pigmentation in breast reconstruction and cosmetic procedures such as permanent makeup. This article describes the technique and its application to head and neck reconstruction. Medical tattooing can be used to improve the cosmetic appearance of head and neck free flaps. There is no donor site morbidity and subtle changes in color can be replicated. The article describes the technique of medical tattooing with the use of illustrative cases. Medical tattooing is a viable alternative for improving the appearance of cutaneous skin paddles following head and neck reconstruction with free flaps. Its advantages include no donor site morbidity, availability of an infinite range of colors, no requirement for general anesthesia, and the ability to use multiple colors in the one flap for complex pigmentation requirements. Its disadvantages include the need for specialized skills and equipment and the fading of color over time.
Three-dimensional assemblies of semiconductor quantum dots in a wide-gap matrix providing an intermediate band for absorption
Authors: Popescu Voicu , Zunger Alex
Published: December 2012

We consider a self-assembled quantum dot (QD) system consisting of the QD itself, the wetting layer and the matrix on a substrate. The electronic structure for various III-V material combinations was determined by atomistic empirical pseudopotential calculations. Taking the widely investigated InAs/GaAs/GaAs(001) system as benchmark, we analyze the changes induced in the energy levels and offsets relevant for a QD-based intermediate band solar cell (IBSC). We explore the effects of (i) the dot material, (ii) the matrix material, and (iii) dot-matrix-substrate combinations that may enable strain balanced structures. Using as unique reference criterion the relative position of the intermediate band inside the band gap of the matrix, we suggest the dot/matrix/substrate combinations InAs/(In,Ga)P/GaAs(001), In(As,Sb)/GaAs/InP(001), and InAs/Ga(As,Sb)/InP(001) as promising candidates for QD-IBSCs.
Tensor hypercontraction. II. Least-squares renormalization
Authors: Parrish Robert M. , Hohenstein Edward G. , Martínez Todd J. , Sherrill C. David
Published: December 2012

The least-squares tensor hypercontraction (LS-THC) representation for the electron repulsion integral (ERI) tensor is presented. Recently, we developed the generic tensor hypercontraction (THC) ansatz, which represents the fourth-order ERI tensor as a product of five second-order tensors [E. G. Hohenstein, R. M. Parrish, and T. J. Martínez, J. Chem. Phys. 137, 044103 (2012)]10.1063/1.4732310. Our initial algorithm for the generation of the THC factors involved a two-sided invocation of overlap-metric density fitting, followed by a PARAFAC decomposition, and is denoted PARAFAC tensor hypercontraction (PF-THC). LS-THC supersedes PF-THC by producing the THC factors through a least-squares renormalization of a spatial quadrature over the otherwise singular 1/r12 operator. Remarkably, an analytical and simple formula for the LS-THC factors exists. Using this formula, the factors may be generated with \documentclass[12pt]{minimal}\begin{document}${\cal O}(N^5)$\end{document}O(N5) effort if exact integrals are decomposed, or \documentclass[12pt]{minimal}\begin{document}${\cal O}(N^4)$\end{document}O(N4) effort if the decomposition is applied to density-fitted integrals, using any choice of density fitting metric. The accuracy of LS-THC is explored for a range of systems using both conventional and density-fitted integrals in the context of MP2. The grid fitting error is found to be negligible even for extremely sparse spatial quadrature grids. For the case of density-fitted integrals, the additional error incurred by the grid fitting step is generally markedly smaller than the underlying Coulomb-metric density fitting error. The present results, coupled with our previously published factorizations of MP2 and MP3, provide an efficient, robust \documentclass[12pt]{minimal}\begin{document}${\cal O}(N^4)$\end{document}O(N4) approach to both methods. Moreover, LS-THC is generally applicable to many other methods in quantum chemistry.
Optical cavity efficacy and lasing of focused ion beam milled GaN/InGaN micropillars
Authors: El-Ella Haitham A. R. , Collins Daniel P. , Kappers Menno J. , Taylor Robert A. , Oliver Rachel A.
Published: December 2012

Focused ion beam milled micropillars employing upper and lower distributed Bragg reflectors (DBRs) and incorporating InGaN quantum dots were analysed both microstructurally and optically. Comparison of the surface characteristics and the optical resonance of pillars milled employing two recipes, using comparatively higher and lower beam currents, were carried out through electron back scatter diffraction, atomic force microscopy and low temperature micro-photoluminescence. Low temperature micro-photoluminescence highlighted singly resolved InGaN quantum dot emission as well as modes with typical quality factors (Q) of ∼200–450 for typical 1–4 μm diameter pillars, while one exceptional 4 μm diameter pillar displayed optically-pumped lasing with a Q of ∼1100 at a threshold of ∼620 kWcm−2. The higher current recipe resulted in pillars with thicker surface amorphous layers, while the lower current recipe resulted in pillars with thinner surface amorphous layers but rougher surfaces. Micropillars milled through the recipe utilising higher beam currents were tentatively shown to possess lower Qs on average, correlating with the thickness of the surface amorphous layer. Finite difference frequency domain simulations in combination with analytical approximations of the various optical loss pathways suggested that surface scattering related optical loss was not significant compared to internal-based and surface absorption-based losses. The magnitude of the internal loss was observed to fluctuate significantly, which was thought to relate to the fluctuating micro-structure within the lower DBR and within the InGaN quantum dot layer.
Influence of geometrical deformation and electric field on transport characteristics through carbon nanotubes
Authors: Mouri Masaaki , Ogawa Matsuto , Souma Satofumi
Published: December 2012

We study computationally the electronic transport properties through mechanically squashed zigzag carbon nanotubes (CNTs) under the uniform electric field perpendicular to the tube axis, based on the tight-binding molecular dynamics method for the structural analysis and the Landauer-Büttiker's formalism for the transport analysis. Our simulations show that the band gaps of the zigzag carbon nanotubes exhibit nonlinear decrease as increasing the deformation ratio in the presence of the external perpendicular electric field, in contrast to the case of zero electric field, where the band gap decreases linearly as increasing the deformation ratio. Such properties allow us to tune the sensitivity of the electromechanical response in CNT devices by applying the external electric field.
The modification of central B/N atom chain on electron transport of graphene nanoribbons
Authors: Xiao Huaping , Chen Yuanping , Xie Yuee , Ouyang Tao , Zhang Ye , Zhong Jianxin
Published: December 2012

The electronic transport properties of hybrid graphene nanoribbons constructed by substituting C atom chain into B (N) atom chain are investigated through using the density functional theory in combination with the nonequilibrium Green's function method. It is found that the hybrid nanoribbon with armchair edge transits from semiconducting to metallic. While the transport properties of hybrid B (N) system with zigzag edge are highly improved with the transmission conductance around the Fermi level increasing to 6G0 (5G0). All these unique transport properties are mainly attributed to the coupling effect between B (N) atoms and C atoms at the interface of hybrid systems, which introduces a pair of bonding and antibonding bands around the Fermi level. The results indicate that such hybrid system is an effective way to modulate the transport properties of graphene nanoribbons.
Detection of organic vapors by graphene films functionalized with metallic nanoparticles
Authors: Gautam Madhav , Jayatissa Ahalapitiya H.
Published: December 2012

Graphene synthesized by chemical vapor deposition has been used to study the sensing behavior of graphene for different organic vapors in ppm level. All the measurements were carried out at a room temperature with dry air as the background gas. Synthesis of graphene was carried out on a copper foil using methane gas as a precursor. The Raman spectroscopy was used to monitor the quality of graphene films transferred to SiO2/Si substrates, revealing the sensing channel to be mostly monolayer, bilayer, or tri-layer graphene. Graphene surface was functionalized with gold and platinum nanoparticles to enhance the gas sensing behavior. The adsorption/desorption behavior of organic vapors in dry air was analyzed based on the change in the conductivity with the different exposure times in different concentrations. Among the vapors tested, the sensitivity was in the order: acetic acid > ethanol > acetone from all surfaces (bare graphene, graphene decorated with gold and platinum nanoparticles). The devices were successfully tested for four key characteristics (response, recovery, repeatability, and reliability) of any practical gas sensors. The dynamic response behavior of the devices was also analyzed and fitted with the first order exponential function relating to the Langmuir approach. Based on the fit, the average response rate was obtained between 0.22% and 1.04% per ppm for different organic vapors with different surfaces. Average response rate of around 0.5% per ppm for organic vapors demonstrates a high sensitivity of the device at the room temperature under the ambient conditions.
Hopping conduction in bismuth modified zinc vanadate glasses: An applicability of Mott's model
Authors: Punia R. , Kundu R. S. , Murugavel S. , Kishore N.
Published: December 2012

The dc conductivity measured in a wide range of temperatures (room temperature to 533.16 K) for glass samples of compositions 50V2O5·xBi2O3·(50-x) ZnO; x = 0, 5, 10, 15, and 20, is discussed in this paper. The temperature dependent dc conductivity has been analyzed in the framework of various theoretical models, which describe the hopping conduction in disordered semiconducting systems. It has been observed that Mott's model of polaron hopping in transition metals is in good agreement with the experimental data in high as well as intermediate temperature regions. The various polaron hopping parameters have also been deduced. It has been ascertained by these estimated quantities and different approaches that the electrical conduction in present glass system is due to non-adiabatic variable range hopping of small polarons. Moreover, it has been found that Mott's and Greaves’ variable range hopping models are in good agreement with the experimental data in the whole studied temperature range in the present investigation.
Scanning nonlinear dielectric microscopy observation of accumulated charges in metal-SiO2-SiN-SiO2-Si flash memory by detecting higher-order nonlinear permittivity
Authors: Honda Koichiro , Cho Yasuo
Published: December 2012

Using scanning nonlinear dielectric microscopy with high-sensitivity capacitance variation detection capability, we succeeded in the high-resolution visualization of accumulated charges in metal-SiO2-SiN-SiO2-Si flash memory by detecting the higher-order (2-4 order) nonlinear permittivity. The obtained image contrast can be interpreted using a higher-order differential coefficient (dnC/dVn) of a quasi-static C-V curve of the SiO2-SiN-SiO2-Si interface capacitance as a function of externally applied voltage. Moreover, by using a higher-order nonlinear image, the charge concentration resolution can be improved. Thus, improved resolution of the spatial charge distribution is expected through improvement of the concentration resolution by the imaging of higher-order nonlinear dielectric terms.
Accurate quantum dynamics calculations using symmetrized Gaussians on a doubly dense Von Neumann lattice
Authors: Halverson Thomas , Poirier Bill
Published: December 2012

In a series of earlier articles [B. Poirier, J. Theor. Comput. Chem. 2, 65 (2003);10.1142/S0219633603000380 B. Poirier and A. Salam, J. Chem. Phys. 121, 1690 (2004);10.1063/1.1767511 B. Poirier and A. Salam, J. Chem. Phys. 121, 1704 (2004)10.1063/1.1767512], a new method was introduced for performing exact quantum dynamics calculations. The method uses a “weylet” basis set (orthogonalized Weyl-Heisenberg wavelets) combined with phase space truncation, to defeat the exponential scaling of CPU effort with system dimensionality—the first method ever able to achieve this long-standing goal. Here, we develop another such method, which uses a much more convenient basis of momentum-symmetrized Gaussians. Despite being non-orthogonal, symmetrized Gaussians are collectively local, allowing for effective phase space truncation. A dimension-independent code for computing energy eigenstates of both coupled and uncoupled systems has been created, exploiting massively parallel algorithms. Results are presented for model isotropic uncoupled harmonic oscillators and coupled anharmonic oscillators up to 27 dimensions. These are compared with the previous weylet calculations (uncoupled harmonic oscillators up to 15 dimensions), and found to be essentially just as efficient. Coupled system results are also compared to corresponding exact results obtained using a harmonic oscillator basis, and also to approximate results obtained using first-order perturbation theory up to the maximum dimensionality for which the latter may be feasibly obtained (four dimensions).
Impact of anisotropic atomic motions in proteins on powder-averaged incoherent neutron scattering intensities
Authors: Kneller Gerald R. , Chevrot Guillaume
Published: December 2012

This paper addresses the question to which extent anisotropic atomic motions in proteins impact angular-averaged incoherent neutron scattering intensities, which are typically recorded for powder samples. For this purpose, the relevant correlation functions are represented as multipole series in which each term corresponds to a different degree of intrinsic motional anisotropy. The approach is illustrated by a simple analytical model and by a simulation-based example for lysozyme, considering in both cases the elastic incoherent structure factor. The second example shows that the motional anisotropy of the protein atoms is considerable and contributes significantly to the scattering intensity.
Preferred armchair edges of epitaxial graphene on 6H-SiC(0001) by thermal decomposition
Authors: Hu T. W. , Ma D. Y. , Ma F. , Xu K. W.
Published: December 2012

Scanning tunneling microscopy is used to study the edge orientation of graphene fabricated by thermal decomposition of 6H-SiC. The exploration on the atomically resolved structures and the patterns in reciprocal space demonstrates that the armchair direction is always parallel to the basic vector of 6 × 6 reconstruction as well as the close-packed direction of 6H-SiC substrate. This can be used as the criterion to characterize the edge direction of graphene. With this method, it is found that armchair edges are preferred in both monolayer and bilayer regions. This special edge certainly will affect the electronic states and consequently the properties.
Explicit invariant manifolds and specialised trajectories in a class of unsteady flows
Authors: Balasuriya Sanjeeva
Published: December 2012

A class of unsteady two- and three-dimensional velocity fields for which the associated stable and unstable manifolds of the Lagrangian trajectories are explicitly known is introduced. These invariant manifolds form the important time-varying flow barriers which demarcate coherent fluids structures, and are associated with hyperbolic trajectories. Explicit expressions are provided for time-evolving hyperbolic trajectories (the unsteady analogue of saddle stagnation points), which are proven to be hyperbolic in the sense of exponential dichotomies. Elliptic trajectories (the unsteady analogue of stagnation points around which there is rotation, i.e., the “centre of a vortex”) are similarly explicitly expressed. While this class of models possesses integrable Lagrangian motion since formed by applying time-dependent spatially invertible transformations to steady flows, their hyperbolic/elliptic trajectories can be made to follow any user-specified path. The models are exemplified through two classical flows: the two-dimensional two-gyre Duffing flow and the three-dimensional Hill's spherical vortex. Extensions of the models to finite-time and nonhyperbolic manifolds are also presented. Given the paucity of explicit unsteady examples available, these models are expected to be useful testbeds for researchers developing and improving diagnostic methods for tracking flow structures in genuinely time-dependent flows.
Effects of the oxygen vacancy concentration in InGaZnO-based resistance random access memory
Authors: Kim Moon-Seok , Hwan Hwang Young , Kim Sungho , Guo Zheng , Moon Dong-Il , Choi Ji-Min , Seol Myeong-Lok , Bae Byeong-Soo , Choi Yang-Kyu
Published: December 2012

Resistance random access memory (RRAM) composed of stacked aluminum (Al)/InGaZnO(IGZO)/Al is investigated with different gallium concentrations. The stoichiometric ratio (x) of gallium in the InGaxZnO is varied from 0 to 4 for intentional control of the concentration of the oxygen vacancies (VO), which influences the electrical characteristics of the RRAM. No Ga in the IGZO (x = 0) significantly increases the value of VO and leads to a breakdown of the IGZO. In contrast, a high Ga concentration (x = 4) suppresses the generation of VO; hence, resistive switching is disabled. The optimal value of x is 2. Accordingly, enduring RRAM characteristics are achieved.
Dynamics of concentric and eccentric compound droplets suspended in extensional flows
Authors: Qu Xiaofeng , Wang Yechun
Published: December 2012

The motion, deformation, and stability of compound droplets in extensional flows are investigated numerically via a three-dimensional spectral boundary element method. We examine the droplet stability under the influences of the capillary number, the inner droplet size and the relative magnitude of the surface tension of the two interfaces composing the compound droplet. The influence of viscosity on the droplet deformation is also discussed. We conclude that a compound droplet with a larger inner droplet and/or smaller inner surface tension is less stable and cannot withstand strong flow. For moderate viscosity ratios, a compound droplet with a more viscous “shell” exhibits larger deformation at steady state. In addition, for an eccentric compound droplet, both the inner and outer droplets tend to migrate away from its original location due to the asymmetry of the problem. The initial location of the inner droplet also influences the droplet stability as well as the migration velocity of the compound droplet.
Crystalline silicon interface passivation improvement with a-Si1−xCx:H and its application in hetero-junction solar cells with intrinsic layer
Authors: Chang Teng-Hsiang , Chu Yen-Ho , Lee Chien-Chieh , Chang Jenq-Yang
Published: December 2012

Excellent passivation of an n-type Czochralski crystalline silicon surface is made possible by the deposition of hydrogenated silicon carbide (Si1−xCx:H) layers in the electron cyclotron resonance chemical vapor deposition. We investigate the structural effect with various CH4/SiH4 dilution ratios, and the lowest effective surface recombination velocity (21.03 cm/s) that can be obtained. We also demonstrate that the Voc can be improved more than 200 mV by inserting Si1−xCx:H layers to form hetero-junction with intrinsic thin layer (HIT) solar cells. The conversion efficiency of the planar HIT solar cell with μc-Si emitter can reach 13%.
Strain modulated transient photostriction in La and Nb codoped multiferroic BiFeO3 thin films
Authors: Jin Zuanming , Xu Yue , Zhang Zhengbing , Lin Xian , Ma Guohong , Cheng Zhenxiang , Wang Xiaolin
Published: December 2012

The coherent longitudinal acoustic (LA) phonons in La and Nb codoped polycrystalline BiFeO3 (Bi0.8La0.2Fe0.99Nb0.01O3 (BLFNO)) films are photo-induced and detected by the ultrafast reflectance spectroscopy. The generation mechanism of LA phonons is strongly connected with the ferroelectric polarization and is attributed to the transient photostriction effect, which is a combination of the optical rectification effect and the electrostriction effect. The strain modulation of sound velocity and out-of-plane elastic properties are demonstrated in BLFNO film on SrTiO3, which gives the insight on the dynamical coupling between electrical polarization and lattice deformation. Our findings are desired for the design of BiFeO3-based photo-driven remote control micro/nano devices.
Mn dopant on the “domain stabilization” effect of aged BaTiO3 and PbTiO3-based piezoelectrics
Authors: Zhang Lixue , Liu Wenfeng , Chen Wei , Ren Xiaobing , Sun Jun , Gurdal Erkan A. , Ural Seyit O. , Uchino Kenji
Published: December 2012

We report that an obvious difference in the “domain stabilization” effect between 1.0 mol. % Mn doped (Ba1−xSrx)TiO3 and (Pb1−xSrx)TiO3 piezoelectrics with a similar c/a ratio and aging treatment, though typically “increased” stabilization effect occurs with the increase of c/a in each system. The three-time larger microscopic defect dipole field Ei in lead-system from P-E measurements suggests the more aligned defect dipoles through kinetically easier hopping of oxygen vacancy originated from local structure rather than the average structure like c/a may be a primary cause of the strong domain stabilization effect. This may help on the hardening functionality improvement of lead-free systems.
Quasi-optical terahertz polarizers enabled by inkjet printing of carbon nanocomposites
Authors: Das Arindam , Schutzius Thomas M. , Megaridis Constantine M. , Subhechha Subhali , Wang Tao , Liu Lei
Published: December 2012

We report an approach for cost-effective manufacturing of THz quasi-optical polarizers by inkjet printing of polymer-carbon nanowhisker (CNW) dispersions. The electromagnetic interference properties of coatings with fixed CNW/polymer composition and varying thickness are quantified by a frequency domain THz spectroscopy system in the range 570–630 GHz. A shielding effectiveness of ∼40 dB is attained for 70 μm-thick coatings. A prototype THz polarizer printed on Mylar film displayed transmission and absorbance that varied with polarization orientation. The degree of polarization for film thickness of ∼1 μm was 0.35. This performance can be improved by refining grid dimensions, increasing coating thickness and adopting multi-layer polarizer structures.
Negative photoconductance in SiO2(Co)/GaAs heterostructure in the avalanche regime
Authors: Lutsev L. V. , Pavlov V. V. , Usachev P. A. , Astretsov A. A. , Stognij A. I. , Novitskii N. N.
Published: December 2012

Negative photoconductance of heterostructures of silicon dioxide films containing cobalt nanoparticles grown on gallium arsenide SiO2(Co)/GaAs has been observed in the avalanche regime. Light with the photon energy less than the bandgap energy of the GaAs creates holes trapped on defects within the GaAs bandgap. This suppresses the avalanche feedback and causes a reduction of the current flowing through the SiO2(Co)/GaAs heterostructure.
Magnetostatic surface wave propagation in a one-dimensional magnonic crystal with broken translational symmetry
Authors: Filimonov Y. , Pavlov E. , Vystostkii S. , Nikitov S.
Published: December 2012

Magnetostatic surface wave propagation through the one-dimensional magnonic crystal with broken translational symmetry developed in an yttrium iron garnet film was experimentally studied. Magnonic crystals were prepared in the form of lattices of etched grooves in yttrium iron garnet film where structural defect was inserted in the center of the lattice in the form of a single defective crest or groove with the width different from those in the lattices. The defect modes within the magnonic bandgaps were detected under conditions corresponding to excitation of the Bragg reflecting resonator formed by the defect.
Dielectrophoretic properties of engineered protein patterned colloidal particles
Authors: Honegger T. , Peyrade D.
Published: December 2012

This work determines the dielectrophoretic response of surface modified polystyrene and silica colloidal particles by experimentally measuring their Clausius-Mossotti factors. Commercial charged particles, fabricated ones coated with fibronectin, and Janus particles that have been grafted with fibronectin on one side only were investigated. We show that the dielectrophoretic response of such particles can be controlled by the modification of the chemistry or the anisotropy of their surface. Moreover, by modelling the polarizabilities of those particles, the dielectric parameters of the particles and the grafted layer of protein can be measured.
Improved current distribution in resistive memory on flexible substrate using nitrogen-rich TaN electrode
Authors: Zheng Zhi-Wei , Cheng Chun-Hu , Chou Kun-I , Liu Ming , Chin Albert
Published: December 2012

Narrow current distribution, good endurance, and low 28 μW switching power are successfully achieved in Ni/GeOx/TiOy/TaN resistive random access memory devices. The good distribution and endurance are attributed to the nitrogen-rich TaN to increase the oxidation resistance and decrease the TaON and oxygen vacancies formation from x-ray photoelectron spectroscopy measurements, where such oxygen vacancies are related to current conduction at high resistance state. In addition, the devices on the flexible polyimide substrate exhibit excellent mechanical endurance upon repeated bending tests, showing their high potential for low-cost flexible memory application.
Dissolved organic carbon mobilisation in relation to variable discharges and environmental flows in a highly regulated lowland river
Authors: Westhorpe Douglas P. , Mitrovic Simon M.
Published: December 2012

The relationships between discharge and dissolved organic carbon (DOC) have been extensively studied in rainfall runoff-driven stream systems. Less is known about discharge and DOC relationships in river systems dependent on floodplain inundation. We examined DOC dynamics and mobilisation over low discharge periods and several larger discharge events in the highly regulated lowland Namoi River, Australia. Stable isotope signatures (δ13C) of various water-column fractions (e.g. 200 µm, fine particulate organic matter) were used to determine the sources of DOC. DOC concentrations over low discharge periods were fairly similar among sites and ranged between 5 and 10 mg L–1. Concentrations during a high-discharge event increased substantially with a mean of 20.4 mg L–1 and a maximum of 44 mg L–1. Significant positive linear relationships were found between DOC concentrations and discharge (P < 0.001, r2 = 0.45). The 13C composition of DOC sampled across the three sites (e.g. –26.2‰) suggests a mixture of terrestrial and aquatic sources, with little downstream variation; however, we would envisage that during periods of high discharge allochthonous sources would dominate. Environmental flows (that are ecologically beneficial, potentially reversing changes brought about by flow regulation) have been allocated to the river, with the intention to increase the amount of DOC delivered to the river. The relationship between DOC and discharge was used to estimate DOC loads to the river under different modelled flow-management scenarios, including without environmental flow, with environmental flow, and simulated natural (low development) flow. On the basis of the modelling results, environmental flows should increase the amount of allochthonous DOC transported within the river in years with moderate and large flow events. Years with low flows did not deliver large loads of allochthonous DOC. The present results showed the potential variability in DOC delivery in relation to floodplain inundation in a lowland river that may not otherwise be detected in rainfall/runoff-driven headwater streams.
Larval anisakid nematodes in teleost fishes from Lizard Island, northern Great Barrier Reef, Australia
Authors: Jabbar Abdul , Asnoussi Abdouslam , Norbury Luke J. , Eisenbarth Albert , Shamsi Shokoofeh , Gasser Robin B. , Lopata Andreas L. , Beveridge Ian
Published: December 2012

A survey was undertaken to characterise larval anisakid nematodes present in teleosts at Lizard Island on the northern Great Barrier Reef. In total, 464 fish were examined from 32 families, 62 genera and 107 species. Anisakid nematodes were found in 46 (9.9%) of the fish examined. Infections in Atherinidae, Lethrinidae, Lutjanidae and Serranidae were moderately prevalent, with the intensities of infection ranging from 1 to 80; whereas in the Sphyraenidae and Scombridae, the prevalence of infection was very high, with intensities ranging from 1 to >375 anisakids. A combined morphological and molecular-phylogenetic approach was employed to identify larval anisakid nematodes to species and/or genotypes. The nematodes examined were identified as Anisakis typica (three genotypes based on molecular characterisation), Terranova Types I (five genotypes) and II (five genotypes) and Hysterothylacium Types IV, V (four genotypes), VI and X. The findings of the present study provide some insights into the distribution of larval anisakid nematodes in coral-reef fishes and a basis for future investigations of anisakid populations in marine fishes.
Contributions of an animal scientist to understanding the biology of the uterus and pregnancy
Authors: Bazer Fuller W.
Published: December 2012

I developed a passion for reproductive biology when taking a course in Physiology of Reproduction at Louisiana State University while preparing to apply for Veterinary School at Texas A&M University. My career path changed. I entered graduate school, obtained a Ph.D. and have enjoyed an academic career conducting research in uterine biology and pregnancy in animal science departments at the University of Florida and at Texas A&M University. My contributions to science include: (1) identification of molecules secreted by or transported by uterine epithelia into the uterine lumen that are critical to successful establishment and maintenance of pregnancy, (2) discovery of steroids and proteins required for pregnancy-recognition signalling and their mechanisms of action in pigs and ruminants, (3) patterns of fetal–placental development and placental transport of nutrients, (4) identification of links between nutrients and components of histotroph that affect fetal–placental development, (5) characterising aspects of the endocrinology of pregnancy and (6) contributing to efforts to exploit the therapeutic value of interferon tau, particularly for treatment of autoimmune and inflammatory diseases. Current research focuses on select nutrients in the uterine lumen, specifically amino acids, glucose and fructose, that affect conceptus development, the therapeutic potential for interferon tau, stromal–epithelial cell signalling whereby progesterone and oestrogen act via steroid receptors in uterine stromal cells to stimulate secretion of growth factors (e.g. fibroblast growth factors and hepatocyte growth factor) that regulate uterine epithelial cells and conceptus trophectoderm, and roles of toll-like receptors expressed by uterine epithelia and conceptus trophectoderm in pregnancy.
Hosting the preimplantation embryo: potentials and limitations of different approaches for analysing embryo - endometrium interactions in cattle
Authors: Ulbrich Susanne E. , Wolf Eckhard , Bauersachs Stefan
Published: December 2012

Ongoing detailed investigations into embryo–maternal communication before implantation reveal that during early embryonic development a plethora of events are taking place. During the sexual cycle, remodelling and differentiation processes in the endometrium are controlled by ovarian hormones, mainly progesterone, to provide a suitable environment for establishment of pregnancy. In addition, embryonic signalling molecules initiate further sequences of events; of these molecules, prostaglandins are discussed herein as specifically important. Inadequate receptivity may impede preimplantation development and implantation, leading to embryonic losses. Because there are multiple factors affecting fertility, receptivity is difficult to comprehend. This review addresses different models and methods that are currently used and discusses their respective potentials and limitations in distinguishing key messages out of molecular twitter. Transcriptome, proteome and metabolome analyses generate comprehensive information and provide starting points for hypotheses, which need to be substantiated using further confirmatory methods. Appropriate in vivo and in vitro models are needed to disentangle the effects of participating factors in the embryo–maternal dialogue and to help distinguish associations from causalities. One interesting model is the study of somatic cell nuclear transfer embryos in normal recipient heifers. A multidisciplinary approach is needed to properly assess the importance of the uterine milieu for embryonic development and to use the large number of new findings to solve long-standing issues regarding fertility.