bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of high energy photons in Z-pinch experiments on primary test stand
Authors: Si Fenni , Zhang Chuanfei , Xu Rongkun , Yuan Xi , Huang Zhanchang , Xu Zeping , Ye Fan , Yang Jianlun , Ning Jiamin , Hu Qingyuan , Zhu Xuebin
Published: August 2015

High energy photons are measured for the first time in wire-array Z-pinch experiments on the Primary Test Stand (PTS) which delivers a current up to 8 MA with a rise time of 70 ns. A special designed detecting system composed of three types of detectors is used to measure the average energy, intensity, and pulse waveform of high energy photons. Results from Pb-TLD (thermoluminescence dosimeter) detector indicate that the average energy is 480 keV (±15%). Pulse shape of high energy photons is measured by the photodiode detector consisted of scintillator coupled with a photodiode, and it is correlated with soft x-ray power by the same timing signal. Intensity is measured by both TLD and the photodiode detector, showing good accordance with each other, and it is 1010 cm−2 (±20%) at 2 m in the horizontal direction. Measurement results show that high energy photons are mainly produced in pinch regions due to accelerated electrons. PTS itself also produces high energy photons due to power flow electrons, which is one order smaller in amplitude than those from pinch region.
Domain evolution with electric field and delineation of extrinsic contributions in (K, Na, Li)(Nb, Ta, Sb)O3 single crystal
Authors: Wang Junjun , Zheng Limei , Yang Bin , Luo Zhenlin , Lu Xiaoyan , Liu Gang , Zhang Rui , Lv Tianquan , Cao Wenwu
Published: August 2015

Extrinsic contributions play an important role in the functionalities of ferroelectric materials, while domain structure evolution is crucial for understanding the extrinsic dielectric and piezoelectric responses. In this work, domain configuration changes with an electric field applied along [001]C in the tetragonal (K, Na, Li)(Nb, Sb, Ta)O3 single crystal were studied by means of polarizing light microscopy. Results show that parts of the spontaneous polarizations in the (001)C plane are switched to [001]C direction, while others still stay in the (001)C plane due to high induced internal stresses. Single domain state cannot be achieved even under a high electric field. After being poled along [001]C, the volume fraction of domains with polarzations in the (001)C plane is still about 25.2%. The extrinsic contributions to the dielectric constant are 15.7% and 27.2% under the E field of 1 kV/cm and under 2 kV/cm, respectively, estimated by the Rayleigh analysis.
Cobalt ferrite nanoparticles under high pressure
Authors: Saccone F. D. , Ferrari S. , Errandonea D. , Grinblat F. , Bilovol V. , Agouram S.
Published: August 2015

We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe2O4) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20–27 GPa to 7.5–12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B0 = 204 GPa) is considerably larger than the value previously reported for bulk CoFe2O4 (B0 = 172 GPa). In addition, when the pressure medium becomes non-hydrostatic and deviatoric stresses affect the experiments, there is a noticeable decrease of the compressibility of the studied sample (B0 = 284 GPa). After decompression, the cobalt ferrite lattice parameter does not revert to its initial value, evidencing a unit cell contraction after pressure was removed. Finally, Raman spectroscopy provides information on the pressure dependence of all Raman-active modes and evidences that cation inversion is enhanced by pressure under non-hydrostatic conditions, being this effect not fully reversible.
Dynamics of gradient formation by intracellular shuttling
Authors: Berezhkovskii Alexander M. , Shvartsman Stanislav Y.
Published: August 2015

A number of important cellular functions rely on the formation of intracellular protein concentration gradients. Experimental studies discovered a number of mechanisms for the formation of such gradients. One of the mechanisms relies on the intracellular shuttling of a protein that interconverts between the two states with different diffusivities, under the action of two enzymes, one of which is localized to the plasma membrane, whereas the second is uniformly distributed in the cytoplasm. Recent work reported an analytical solution for the steady state gradient in this mechanism, obtained in the framework of a one-dimensional reaction-diffusion model. Here, we study the dynamics in this model and derive analytical expressions for the Laplace transforms of the time-dependent concentration profiles in terms of elementary transcendental functions. Inverting these transforms numerically, one can obtain time-dependent concentration profiles of the two forms of the protein.
Experimental demonstration of a surface-electrode multipole ion trap
Authors: Maurice Mark , Allen Curtis , Green Dylan , Farr Andrew , Burke Timothy , Hilleke Russell , Clark Robert
Published: August 2015

We report on the design and experimental characterization of a surface-electrode multipole ion trap. Individual microscopic sugar particles are confined in the trap. The trajectories of driven particle motion are compared with a theoretical model, both to verify qualitative predictions of the model and to measure the charge-to-mass ratio of the confined particle. The generation of harmonics of the driving frequency is observed as a key signature of the nonlinear nature of the trap. We remark on possible applications of our traps, including to mass spectrometry.
Nonlinear modes of an intense laser beam interacting with a periodic lattice of nanoparticle
Authors: Sepehri Javan N. , Homami S. H. H.
Published: August 2015

Self-guided nonlinear propagation of an intense laser beam through a periodic lattice of nanoparticle is studied. Using a perturbative method, a cubic nonlinear wave equation describing the laser-nanoparticle interaction in the weakly relativistic regime is derived. Transverse Eigen modes of the laser, nonlinear dispersion relation and its related group velocity are obtained. It is shown that the best fitted function to the transverse profile is Gaussian. Effect of the laser amplitude and also the ratio of nanoparticles radius to their separation on the nonlinear dispersion and amplitude profiles are investigated. It is found that the increase in the just mentioned parameters leads to the localization of transverse profile around the propagation axis.
Dynamics of a wire-to-cylinder atmospheric pressure high-voltage nanosecond discharge
Authors: Levko Dmitry , Raja Laxminarayan L.
Published: August 2015

The dynamics of a wire-to-cylinder atmospheric pressure high-voltage nanosecond discharge is studied by the one-dimensional Particle-in-Cell Monte Carlo collisions model in cylindrical coordinates. The x-ray photons emitted from the anode are found to be inconsequential to the generation of dense plasma in the gap. Rather, the electron impact ionization resulting from acceleration of naturally occurring background electrons in the discharge gap are enough to explain the generation of high-density (∼1015 cm−3) non-equilibrium plasma. The influence of the high-voltage rise time on the plasma parameters is discussed.
Where is the cosmic-ray modulation boundary of the heliosphere?
Authors: Zhang Ming , Luo Xi , Pogorelov Nikolai
Published: August 2015

The intensity of Galactic cosmic rays in the heliosphere is modulated by solar activities. The outer boundary where the solar modulation begins has always been a subject matter of debate in the cosmic-ray and heliophysics community. Various experimental methods and theoretical model calculations have been used to determine the boundary. Although the heliopause was always suspected to be the boundary, it is only until very recently after Voyager 1 had crossed the heliopause did we confirm that the boundary is indeed the heliopause. In this paper, we use a model simulation and detailed Voyager observation of cosmic rays at the heliopause crossing to show that the modulation boundary, in fact, is a fraction of an AU beyond the heliopause. Such a conclusion requires a very low turbulence level of the interstellar magnetic field in the outer heliosheath. According to the quasi-linear theory, a low level of turbulence should result in a very large diffusion coefficient parallel to the magnetic field and a very small perpendicular diffusion coefficient. For the first time, we are confident that Voyager 1 has obtained the truly pristine local interstellar cosmic-ray spectra down to the energies below 1 MeV. The cosmic-ray intensity is rapidly filtered by a thin layer of the interstellar magnetic field immediately outside of the heliopause. Its filtration amount depends on the conditions of magnetic field turbulence on the both sides of the heliopause, thus making it solar-cycle dependent as well.
The role of acoustofluidics in targeted drug delivery
Authors: Bose Nilanjana , Zhang Xunli , Maiti Tapas K. , Chakraborty Suman
Published: August 2015

With the fast development of acoustic systems in clinical and therapeutic applications, acoustically driven microbubbles have gained a prominent role as powerful tools to carry, transfer, direct, and target drug molecules in cells, tissues, and tumors in the expanding fields of targeted drug delivery and gene therapy. The aim of the present study is to establish a biocompatible acoustic microfluidic system and to demonstrate the generation of an acoustic field and its effects on microbubbles and biological cells in the microfluidic system. The acoustic field creates non-linear oscillations of the microbubble-clusters, which results in generation of shear stress on cells in such microsystems. This effectively helps in delivering extracellular probes in living cells by sonoporation. The sonoporation is investigated under the combined effects of acoustic stress and hydrodynamic stress during targeted drug and gene delivery.
Defect engineered d ferromagnetism in tin-doped indium oxide nanostructures and nanocrystalline thin-films
Authors: Khan Gobinda Gopal , Ghosh Shyamsundar , Sarkar Ayan , Mandal Guruprasad , Mukherjee Goutam Dev , Manju Unnikrishnan , Banu Nasrin , Dev Bhupendra Nath
Published: August 2015

Origin of unexpected defect engineered room-temperature ferromagnetism observed in tin-doped indium oxide (ITO) nanostructures (Nanowires, Nano-combs) and nanocrystalline thin films fabricated by pulsed laser deposition has been investigated. It is found that the ITO nanostructures prepared under argon environment exhibit strongest ferromagnetic signature as compared to that nanocrystalline thin films grown at oxygen. The evidence of singly ionized oxygen vacancy (V0+) defects, obtained from various spectroscopic measurements, suggests that such V0+ defects are mainly responsible for the intrinsic ferromagnetic ordering. The exchange interaction of the defects provides extensive opportunity to tune the room-temperature d0 ferromagnetism and optical properties of ITOs.
Silver coated nickel nanotip arrays for low concentration surface enhanced Raman scattering
Authors: Nash Ariel P. , Ye Dexian
Published: August 2015

A two-step glancing angle deposition method is developed to fabricate hierarchical metal nanostructures for surface enhanced Raman scattering (SERS). Nanotip arrays, which consist of a thin layer of silver on nickel nanoneedles, are deposited on silicon substrates by this method. Rhodamine 6G (R6G) is used to demonstrate the sensitivity of SERS at the near attomolar level. The scaling of Raman intensity with the concentration of R6G is related to the Langmuir-Freundlich isotherm.
The dependency of different stress-level SiN capping films and the optimization of D-SMT process for the device performance booster in Ge n-FinFETs
Authors: Liao M.-H. , Chen P.-G.
Published: August 2015

The capping stressed SiN film is one of the most important process steps for the dislocation stress memorization technique (D-SMT), which has been used widely in the current industry, for the electron mobility booster in the n-type transistor beyond the 32/28 nm technology node. In this work, we found that the different stress-level SiN capping films influence the crystal re-growth velocities along different directions including [100] and [110] directions in Ge a lot. It can be further used to optimize the dislocation angle in the transistor during the D-SMT process and then results in the largest channel stress distribution to boost the device performance in the Ge n-FinFETs. Based on the theoretical calculation and experimental demonstration, it shows that the Ge three dimensional (3D) n-FinFETs device performance is improved ∼55% with the usage of +3 GPa tensile stressed SiN capping film. The channel stress and dislocation angle is ∼2.5 GPa and 30°, measured by the atomic force microscope-Raman technique and transmission electron microscopy, respectively.
Lateral manipulation and interplay of local Kondo resonances in a two-impurity Kondo system
Authors: Ren Jindong , Wu Xu , Guo Haiming , Pan Jinbo , Du Shixuan , Luo Hong-Gang , Gao Hong-Jun
Published: August 2015

The atomic-scale spatial relationship of a two-impurity Kondo system has been determined at varying lateral distance by scanning tunneling microscopy (STM) and spectroscopy. The localized spins of two cobalt magnetic adatoms that are placed on different electrodes of an STM form two individual Kondo singlet states, each showing quite different Kondo coupling, i.e., the tip-Kondo with low Kondo temperature and the sample-Kondo with high Kondo temperature. The differential conductance dI/dV spectra show the continuous changes of the resonance peak feature when approaching the Kondo tip laterally to the local sample-Kondo impurity on the surface. The result indicates a notable interplay between these two Kondo systems. We propose a convolution model based on the q factor of the sample-Kondo (qs) and tip-Kondo (qt) to interpret the change of various tunneling channels and the evolution of the experimental spectra.
Communication: Spectroscopic consequences of proton delocalization in OCHCO+
Authors: Fortenberry Ryan C. , Yu Qi , Mancini John S. , Bowman Joel M. , Lee Timothy J. , Crawford T. Daniel , Klemperer William F. , Francisco Joseph S.
Published: August 2015

Even though quartic force fields (QFFs) and highly accurate coupled cluster computations describe the OCHCO+ cation at equilibrium as a complex between carbon monoxide and the formyl cation, two notable and typical interstellar and atmospheric molecules, the prediction from the present study is that the equilibrium C∞v structure is less relevant to observables than the saddle-point D∞h structure. This is the conclusion from diffusion Monte Carlo and vibrational self-consistent field/virtual state configuration interaction calculations utilizing a semi-global potential energy surface. These calculations demonstrate that the proton “rattle” motion (ν6) has centrosymmetric delocalization of the proton over the D∞h barrier lying only 393.6 cm−1 above the double-well OCHCO+ C∞v minima. As a result, this molecule will likely appear D∞h, and the rotational spectrum will be significantly dimmer than the computed equilibrium 2.975 D center-of-mass dipole moment indicates. However, the proton transfer fundamental, determined to be at roughly 300 cm−1, has a very strong intensity. This prediction as well as those of other fundamentals should provide useful guides for laboratory detection of this cation. Finally, it is shown that the two highest energy QFF-determined modes are actually in good agreement with their vibrational configuration interaction counterparts. These high-level quantum chemical methods provide novel insights into this fascinating and potentially common interstellar molecule.
Terahertz emission from thin metal films with porous nanostructures
Authors: Zhang Liangliang , Buccheri Fabrizio , Zhang Cunlin , Zhang X.-C.
Published: August 2015

We characterized the terahertz emission from a thin metal film with quasi-randomly distributed porous nanostructures. Unlike many demonstrated nanostructured metal terahertz sources, the emission is in the forward direction when the laser excitation illuminates the metal film at normal incidence, making its integration in a time-domain terahertz system straightforward. We attribute the generation mechanism to optical rectification. Moreover, we observe a deviation from the expected linear scaling of the terahertz electric field with excitation laser pulse energy, which we relate to thermal heating of the emitter.
Comparative study on the charge-trapping properties of TaAlO and ZrAlO high-k composites with designed band alignment
Authors: Lu W. , Wei C. Y. , Jiang K. , Liu J. Q. , Lu J. X. , Han P. , Li A. D. , Xia Y. D. , Xu B. , Yin J. , Liu Z. G.
Published: August 2015

The charge-trapping memory (CTM) structures Pt/Al2O3/TaAlO/Al2O3/p-Si and Pt/Al2O3/ZrAlO/Al2O3/p-Si were fabricated by using rf-sputtering and atomic layer deposition techniques, in which the potentials at the bottom of the conduction band (PBCB) of high-k composites TaAlO and ZrAlO were specially designed. With a lower PBCB difference between TaAlO and p-Si than that between ZrAlO and p-Si, TaAlO CTM device shows a better charge-trapping performance. A density of trapped charges 2.88 × 1013/cm2 at an applied voltage of ±7 V was obtained for TaAlO CTM device, and it could keep about 60% of initially trapped charges after 10 years. It was suggested that the PBCB difference between high-k composite and p-Si dominates their charge-trapping behaviors.
The impact of selecting for increased ewe fat level on reproduction and its potential to reduce supplementary feeding in a commercial composite flock
Authors: Walkom S. F. , Brien F. D. , Hebart M. L. , Pitchford W. S.
Published: August 2015

In southern Australian grazing systems, energy availability typically exceeds energy requirements. Grazing systems are likely to have higher profitability if ewes can utilise this relatively cheap feed by gaining more condition (muscle and fat) and then mobilising it when feed is expensive. The present paper focusses on the importance of genetic merit for fat on the lifetime productivity of the ewe within a commercial operation. The analysis was carried out on a maternal composite stud flock in Holbrook, New South Wales. Ultrasound fat and muscle depth were measured on 2796 ewes as lambs at post-weaning and as adult ewes, to determine the genetic relationship between young and adult body composition. The hypothesis of the paper is that selection for increased fat at young age will improve body condition of adult ewes, which will lead to improved reproduction and potentially reduced requirements for supplementary feeding. Given that the difference in feed cost between times of abundance and shortage is likely to be larger, the system may become more profitable despite being less efficient (owing to increased feed intake). Our results indicated that selection for scanned post-weaning fat and muscle depth in lambs should lead to increased fat muscle and body condition in the breeding ewe because of strong genetic correlation estimates between the post-weaning and adult traits of 0.68–0.99. The influence of body composition traits on reproduction (number of lambs weaned) within the stud flock was weak. However, it is hypothesised that by genetically increasing post-weaning fat depth in ewes, producers could improve profitability by reducing the demands for supplementary feeding.
Nuclear transfer alters placental gene expression and associated histone modifications of the placental-specific imprinted gene pleckstrin homology-like domain, family A, member 2 (PHLDA2) in cattle
Authors: Arnold Daniel R. , Gaspar Roberta C. , da Rocha Carlos V. , Sangalli Juliano R. , de Bem Tiago H. C. , Corrêa Carolina A. P. , Penteado João C. T. , Meirelles Flavio V. , Lopes Flavia L.
Published: August 2015

Abnormal placental development is frequent in nuclear transfer (NT) pregnancies and is likely to be associated with altered epigenetic reprogramming. In the present study, fetal and placental measurements were taken on Day 60 of gestation in cows with pregnancies produced by AI, IVF and NT. Placentas were collected and subjected to histological evaluation, the expression of genes important in trophoblast differentiation and expression of the placental imprinted gene pleckstrin homology-like domain, family A, member 2 (PHLDA2), as well as chromatin immunoprecipitation (ChIP) for histone marks within the promoter of PHLDA2. Fewer binucleated cells were observed in NT cotyledons, followed by IVF and AI cotyledons (P < 0.05). Expression of heart and neural crest derivatives expressed 1 (HAND1), placental lactogen (PL), pregnancy-associated glycoprotein 9 (PAG-9) and PHLDA2 was elevated in NT cotyledons compared with AI cotyledons. Expression of PHLDA2 was higher in IVF than AI samples (P < 0.05). ChIP revealed an increase in the permissive mark dimethylation of lysine 4 on histone H3 (H3K4me2), surprisingly associated with the silent allele of PHLDA2, and a decrease in the inhibitory mark H3K9me2 in NT samples. Thus, genes critical for placental development were altered in NT placentas, including an imprinted gene. Allele-specific changes in the permissive histone mark in the PHLDA2 promoter indicate misregulation of imprinting in clones. Abnormal trophoblast differentiation could have resulted in lower numbers of binucleated cells following NT. These results suggest that the altered expression of imprinted genes associated with NT are also caused by changes in histone modifications.
Velocities of unloaded muscle filaments are not limited by drag forces imposed by myosin cross-bridges
Authors: Brizendine Richard K. , Alcala Diego B. , Carter Michael S. , Haldeman Brian D. , Facemyer Kevin C. , Baker Josh E. , Cremo Christine R.
Published: August 2015

Significance

In vitro experiments that measure relative sliding velocities between actin and myosin filaments give insight into how the muscle motor protein myosin works in muscle. We show that when the physiological filamentous myosin moves along actin filaments, the velocities cannot be explained by the prevailing theory. Instead, we propose a paradigm in which myosin heads undergo unloaded “powerstrokes” rather than work in mechanical opposition to each other during contraction. This model is consistent with unloaded shortening velocities measured in muscle.
The political economy of concurrent partners: toward a history of sex–love–gift connections in the time of AIDS
Authors: Hunter Mark
Published: August 2015

Over the last decade, one of the most influential explanations for high HIV prevalence in sub-Saharan Africa is the existence of sexual networks characterised by concurrent partners. Recently, however, a growing number of scholars have challenged the evidential basis for the concurrency argument. While this dispute has led to a call for more sophisticated quantitative methods to measure concurrency, this article widens the discussion to emphasise the political economic roots and qualitative dimension of concurrent partnered relations. Specifically, the paper argues for the importance of situating concurrency within key historical processes and, to that end, gives special consideration to the growth of ‘transactional sex' – non-prostitute but material relations between men and women. Critics of the concurrency–HIV thesis have sometimes dismissed as anecdotal accounts of sex–gift exchanges in Africa. Yet by exploring through an ethnographic/historical lens the changing configuration of sex, love and gifts in South Africa, this article illuminates different manifestations of concurrency, including connections between concurrency and condom use.
Revisiting the economics of transactional sex: evidence from Tanzania
Authors: Deane Kevin , Wamoyi Joyce
Published: August 2015

Transactional sex has been identified as one of the key structural drivers of the HIV epidemic. Mainstream economic analyses of this practice primarily conceptualise transactional sex in the language of rational choice, with the focus on behavioural decisions that women make over whether to engage in transactional interactions (or not). However, whilst providing some important insights in relation to the role of poverty and the importance of acknowledging that women are more than passive agents, these approaches fail to address the social and economic complexities of this practice that are reflected in the broader literature. Further, due to the technical framework used, there is a failure to deal with the broader socio-economic and historical underpinnings of this practice. Using evidence from fieldwork undertaken in Tanzania, the authors revisit the economics of transactional sex, and offer an alternative economic approach to understanding this practice. They explore the notion that transactional sex is an established local sexual norm, and how this norm is creatively applied and reapplied in a range of situations by different actors, including through participation in local value chains. Their analysis has a number of implications for future prevention efforts that differ from the current focus on microfinance as a means of empowering women.
Gas phase synthesis of two ensembles of silicon nanoparticles
Authors: Mohan A , de Jong M M , Poulios I , Schropp R E I , Rath J K
Published: August 2015

Dusty plasmas provide a very favorable environment for the growth of silicon nanocrystals. For application of silicon nanocrystals in a solar cell, the fabrication of monodisperse silicon quantum dots has been challenging. We report a single step method to synthesize silicon (Si) nanoparticles in a custom designed dedicated plasma reactor. The nanoparticles produced in the gas phase belong to two different phases exhibiting different structural and optical properties. Particles made in the bulk of the plasma are aggregates of crystalline particles with a mean size of 100 nm. Particles made in locally enhanced plasma regions produced at holes present in the grounded electrode contain free-standing quantum sized particles with crystallites (with mean size of 2.95 nm) embedded within an amorphous matrix. We provide insight on different plasma processes leading to the formation of aggregates and free-standing particles. We hypothesize that the free standing particles are formed due to the excess energetic electrons present in locally enhanced discharges.
Model-based analysis of keratin intermediate filament assembly
Authors: Martin Ines , Leitner Anke , Walther Paul , Herrmann Harald , Marti Othmar
Published: August 2015

The cytoskeleton of epithelial cells consists of three types of filament systems: microtubules, actin filaments and intermediate filaments (IFs). Here, we took a closer look at type I and type II IF proteins, i.e. keratins. They are hallmark constituents of epithelial cells and are responsible for the generation of stiffness, the cellular response to mechanical stimuli and the integrity of entire cell layers. Thereby, keratin networks constitute an important instrument for cells to adapt to their environment. In particular, we applied models to characterize the assembly of keratin K8 and K18 into elongated filaments as a means for network formation. For this purpose, we measured the length of in vitro assembled keratin K8/K18 filaments by transmission electron microscopy at different time points. We evaluated the experimental data of the longitudinal annealing reaction using two models from polymer chemistry: the Schulz–Zimm model and the condensation polymerization model. In both scenarios one has to make assumptions about the reaction process. We compare how well the models fit the measured data and thus determine which assumptions fit best. Based on mathematical modelling of experimental filament assembly data we define basic mechanistic properties of the elongation reaction process.
Dark current measurements in humid SF6: influence of electrode roughness, relative humidity and pressure
Authors: Zavattoni L , Hanna R , Lesaint O , Gallot-Lavallée O
Published: August 2015

The measurement of ‘dark current’ in pressurized SF6 at high electric field is performed using electrodes with a coaxial geometry. To identify the main mechanisms involved in measured currents, the influences of electrode roughness, gas pressure and relative humidity have been investigated. The experimental results reveal that charge injection from the electrode constitute the predominant process responsible for the dark current. The latter is nearly identical in positive and negative polarities, and shows an exponential increase versus the relative humidity and the electric field. The analysis of results shows that under high electric field, the emission of charged water clusters from the water films adsorbed on electrodes probably constitutes the main mechanism of charge emission.
The defect-induced fracture behaviors of hexagonal boron-nitride monolayer nanosheets under uniaxial tension
Authors: Qi-lin Xiong , Zhen-huan Li , Xiao-geng Tian
Published: August 2015

Due to its excellent mechanical and electrical insulating properties, the hexagonal boron-nitride (h-BN) monolayer nanosheet is regarded as a complementary addition to graphene. However, its mechanical strength can be significantly affected by various defects pre-existing in it, such as a Stone–Wales defect, a vacancy defect, an atomic anti-site defect, etc. In this work, the influences of various pre-existing defects on the fracture behaviors of an h-BN monolayer nanosheet are investigated carefully using molecular dynamics simulation. The results show that the nucleation and evolution of a fracture induced by defects in the h-BN monolayer nanosheet are directional, and that the crack always starts from the location which has a weak bond energy. An unexpected observation is that the defect propagates mostly in the zigzag direction but occasionally in the armchair direction. The fracture strength and the fracture strain of the h-BN monolayer nanosheet are reduced at different extents due to the various pre-existing defects. Additionally, for the defective h-BN monolayer nanosheets, the fracture strength and strain measured in the armchair direction is much higher than the strength found in the zigzag direction. However, the strengths measured in the armchair and zigzag directions for the defect-free h-BN monolayer nanosheets almost are identical which implies that the armchair direction has a stronger ability to resist various defects compared to the zigzag direction.
Investigations of LHW-plasma coupling and current drive at high density related to H-mode experiments in EAST
Authors: Ding B.J. , Li Y.C. , Zhang L. , Li M.H. , Wei W. , Kong E.H. , Wang M. , Xu H.D. , Wang S.L. , Xu G.S. , Zhao L.M. , Hu H.C. , Jia H. , Cheng M. , Yang Y. , Liu L. , Zhao H.L. , Peysson Y. , Decker J. , Goniche M. , Amicucci L. , Cesario R. , Tuccillo A.A. , Baek S.G. , Parker R. , Bonoli P.T. , Paoletti F. , Yang C. , Shan J.F. , Liu F.K. , Zhao Y.P. , Gong X.Z. , Hu L.Q. , Gao X. , Wan B.N. , Li J.G.
Published: August 2015

Two important issues in achieving lower hybrid current drive (LHCD) high confinement plasma in EAST are to improve lower hybrid wave (LHW)-plasma coupling and to drive the plasma current at a high density. Studies in different configurations with different directions of toroidal magnetic field (B
t) show that the density near the antenna is affected by both the radial electric field induced by plasma without a LHW (E
r_plasma) in the scrape off layer (SOL), and the radial electric field induced by LHW power (E
r_LH) near the grill. Investigations indicate that E

r
  ×  B

t
in the SOL leads to a different effect of configuration on the LHW-plasma coupling and E

r_LH
  ×  B

t
accounts for the asymmetric density behaviour in the SOL observed in the experiments, where E
r is the total radial electric field in the SOL. Modelling of parametric instability (PI), collisional absorption (CA) and scattering from density fluctuations (SDF) in the edge region, performed considering the parameters of high density LHCD experiments in EAST, has shown that these mechanisms could be responsible for the low current drive (CD) efficiency at high density. Radiofrequency probe spectra, useful for documenting PI occurrence, show sidebands whose amplitude in the case of the lithiated vacuum chamber is smaller than in the case of poor lithiation, consistently with growth rates from PI modeling of the respective reference discharges. Since strong lithiation is also expected to diminish the parasitic effect on the LHCD of the remaining possible mechanisms, this appears to be a useful method for improving LHCD efficiency at a high density.
Quality, Safety, and Value in Pediatric Orthopaedic Surgery
Authors: Glotzbecker Michael P. , Wang Kevin , Waters Peter M. , McCarthy James , Flynn John M. , Vitale Michael G.
Published: August 2015

Enhancing patient safety and the quality of care continues to be a focus of considerable public and professional interest. We have made dramatic strides in our technical ability to care for children with pediatric orthopaedic problems, but it has become increasingly obvious that there are also significant opportunities to improve the quality, safety, and value of the care we deliver. The purpose of this article is to introduce pediatric orthopaedic surgeons to the rationale for and principles of quality improvement and to provide an update on quality, safety, and value projects within Pediatric Orthopaedic Society of North America.
Gait Pattern and Lower Extremity Alignment in Children With Diastrophic Dysplasia
Authors: Bayhan Ilhan A. , Er Mehmet S. , Nishnianidze Tristan , Ditro Colleen , Rogers Kenneth J. , Miller Freeman , Mackenzie William G.
Published: August 2015

Background:

The aim of this study was to describe the dynamic lower extremity alignment in children with diastrophic dysplasia (DD) by 3-dimensional gait analyses. Our main hypothesis was that gait kinematics and kinetics are different than the age-normalized population and patellar dislocation can alter the gait in patients with DD.

Methods:

A retrospective review of clinical data and radiographs was conducted for patients with DD who had gait analysis before lower extremity skeletal surgery excluding foot procedures. Lower extremity range of motion was measured. The Pediatric Outcomes Data Collection Instrument (PODCI) was administered to parents to evaluate their children’s functional status. Gait laboratory data were collected to compare the hip and knee kinematics in cases with and without patellar dislocation. Anteroposterior standing radiographs were taken for all patients to assess the correlation between measurements (clinical, radiologic, and gait) for coronal knee alignment.

Results:

Thirty lower extremities of 15 children (7 females and 8 males) were evaluated. The mean age was 7.4±3 years, the mean height was 97.7±15 cm (z=−5.1), and the mean weight was 20.6±6.2 kg (z=−0.8). The DD PODCI subscores were statistically significantly lower (P<0.05) than the average stature for developing children, except for the happiness score. Gait analysis, compared between all DD and an age-normalized average stature group, showed decreased forward velocity, step length, and stride length with an increased average forward tilt of the trunk and pelvis, hip flexion, hip adduction, and internal rotation (P<0.001). Delta hip and knee motion were also decreased (P<0.001). The patella was dislocated in 19 (63.3%) and central in 11 (36.6%) knees. Comparison of the minimum knee and hip flexion at the stance phase demonstrated increased crouch gait in the patellar dislocation group (P<0.001). Knee alignment measurements between clinical examination and gait analysis showed moderate correlation (r, 0.476; P=0.008).

Conclusions:

Children with DD demonstrated lower PODCI subscores except for happiness. Gait analysis showed limited lower extremity function of the children with DD in our study group. Patella dislocation group had increased crouch gait.

Levels of Evidence:

Level III—diagnostic study.
Temperature Change When Drilling Near the Distal Femoral Physis in a Skeletally Immature Ovine Model
Authors: Tenfelde Allison M. , Esquivel Amanda O. , Cracchiolo Allison M. , Lemos Stephen E.
Published: August 2015

Background:

The possibility of physeal injury during anterior cruciate ligament reconstruction in the pediatric population is a concern. The purpose of this study was to determine whether drilling at or near the physis could cause a temperature increase that could trigger chondrolysis.

Methods:

Skeletally immature cadaveric lamb distal femurs were used for this study and randomly placed in 1 of 6 groups (n=10 in each group). We examined the 8 and 10 mm Flipcutter at a distance of 0.5 mm from the physis and an 8 and 10 mm acorn-tipped reamer at a distance of 0.5 and 3.0 mm from the physis. During drilling, temperature change at the distal femoral physis was continuously measured until the temperature decreased to the original value.

Results:

An interreamer comparison yielded a significant difference when drilling 0.5 mm from the physis (P=0.001). Pair-wise Mann-Whitney post hoc tests were performed to further evaluate the differences among the groups. The 8 mm FlipCutter had a significantly higher maximum temperature (39.8±1.4°C) compared with the 10 mm FlipCutter (38.0±0.6°C,P=0.001), 8 mm acorn-tipped reamer (38.1±0.9°C,P=0.007), and 10 mm acorn-tipped reamer (37.5±0.3°C,P<0.001).

Conclusions:

The risk of thermal-induced injury to the physis is low with an all epiphyseal drilling technique, when a traditional acorn-tipped reamer over a guidepin is utilized, even if the drilling occurs very close to the physis. In addition, the risk of drilling with a FlipCutter is low, but may be greater than a traditional reamer.

Clinical Relevance:

Thermal-induced necrosis is a realistic concern, due to the characteristics of the distal femoral physis, and the propensity for this physis to respond poorly to injury. Our study supports that drilling near the physis can be done safely, although smaller reamers and nontraditional designs may generate higher heat.

Level of Evidence:

Level I—basic science.
Outcomes of Hemiepiphyseal Stapling for Genu Valgum Deformities in Patients With Multiple Hereditary Exostoses: A Comparative Study of Patients With Deformities of Idiopathic Cause
Authors: Kang Seungcheol , Kim Jae Young , Park Soo-Sung
Published: August 2015

Background:

Patients with multiple hereditary exostoses (MHE) frequently present with a genu valgum deformity. Temporary hemiepiphysiodesis, such as hemiepiphyseal stapling, is a relatively safe surgical method to correct angular deformities in skeletally immature patients, but its outcomes for genu valgum deformity in MHE patients have not been extensively reported. We investigated the outcomes of hemiepiphyseal stapling in MHE patients (MHE group) and compared those with the outcomes in patients with idiopathic deformities (idiopathic group) after adjusting for potential bias.

Methods:

Data from 70 limbs with genu valgum deformity (15 MHE and 55 idiopathic), which had undergone hemiepiphyseal stapling, were retrospectively reviewed. The outcomes were focused on the achievement of satisfactory correction and the velocity of correction. The independent effects of each characteristic on each outcome were investigated using multivariate analyses. The outcomes between the groups were also compared after 1:2 matching using propensity score analysis.

Results:

The mean valgus angle of the MHE group was 7.4±4.1 degrees at stapling and was corrected to 1.3±3.0 degrees at staple removal. The rate of satisfactory corrections was not different between the MHE and idiopathic groups (67% and 70%, respectively, P=0.820). However, the correction velocity was significantly lower in the MHE group than in the idiopathic group on both multivariate analysis (P=0.001) and matching comparison (4.4 vs. 7.9 degrees/y, P<0.001). The duration of correction was longer in the MHE group than in the idiopathic group by approximately half a year (1.5±0.6 vs. 0.9±0.3 y, respectively, P=0.003).

Conclusions:

In MHE patients with genu valgum deformity, satisfactory correction can be achieved by hemiepiphyseal stapling and is comparable with that seen in idiopathic patients. However, the MHE group showed lower correction velocity and required a longer time by about one half year for correction compared with the idiopathic group. Temporary hemiepiphysiodesis should be considered at an earlier age for patients with MHE compared with those with idiopathic deformity.

Level of Evidence:

Level III—prognostic study.
Pediatric Orthopaedic Providers’ Views on Transition From Pediatric to Adult Care
Authors: Fishman Laurie N. , DiFazio Rachel , Miller Patricia , Shanske Susan , Waters Peter M.
Published: August 2015

Background:

Surgical specialties are underrepresented in the discussions regarding transition and transfer of patients to adult care. We sought the pediatric orthopaedic perspective on types of patients seen into adulthood, age cut-offs, triggers for transfer, and barriers to transition. We examined provider demographic factors that may influence perspectives.

Methods:

An internet-based survey was sent to all members of the Pediatric Orthopaedic Society of North America and the Pediatric Orthopaedic Practitioner Society. Responses were voluntary and anonymous.

Results:

Response rates were 27% for the Pediatric Orthopaedic Society of North America and 24% for the Pediatric Orthopaedic Practitioner Society. Most respondents (70%) care for patients over the age of 25 years and many (35%) for patients over the age of 40. The most common conditions cared for were neuromuscular and congenital disorders. Respondents who worked in a fully salaried model reported caring for fewer of these adult patients compared with those working in other types of payment structure (P<0.001). Respondents working in free-standing children’s hospitals reported fewer patients over 30 years old compared with nonchildren’s hospital settings (P<0.001). There were no significant differences between profit-based and nonprofit settings. The top triggers for transfer to adult providers were: (1) adult comorbidities; (2) transition to medical specialist; and (3) institutional policy. The top barriers to transfer were: (1) lack of qualified adult providers; (2) institutional policy; and (3) on-going surgical issues.

Conclusions:

Many providers care for older patients, often using external triggers for transfer to adult care. Financial considerations may need to be further explored. Variation in care may be aided by national society guidelines.

Level of Evidence:

Level III—survey research.
Antidepressant Use in the Elderly Is Associated With an Increased Risk of Dementia
Authors: Wang Chenkun , Gao Sujuan , Hendrie Hugh C. , Kesterson Joe , Campbell Noll L. , Shekhar Anantha , Callahan Christopher M.
Published: August 2015

A retrospective cohort study was conducted including 3688 patients age 60 years or older without dementia enrolled in a depression screening study in primary care clinics. Information on antidepressant use and incident dementia during follow-up was retrieved from electronic medical records. The Cox proportional hazard models were used to compare the risk for incident dementia among 5 participant groups: selective serotonin re-uptake inhibitors (SSRI) only, non-SSRI only (non-SSRI), mixed group of SSRI and non-SSRI, not on antidepressants but depressed, and not on antidepressants and not depressed. SSRI and non-SSRI users had significantly higher dementia risk than the nondepressed nonusers (hazard ratio [HR]=1.83, P=0.0025 for SSRI users and HR=1.50, P=0.004 for non-SSRI users). In addition, SSRIs users had significantly higher dementia risk than non-users with severe depression (HR=2.26, P=0.0005). Future research is needed to confirm our results in other populations and to explore potential mechanism underlying the observed association.
DIS3 shapes the RNA polymerase II transcriptome in humans by degrading a variety of unwanted transcripts
Authors: Szczepińska Teresa , Kalisiak Katarzyna , Tomecki Rafal , Labno Anna , Borowski Lukasz S. , Kulinski Tomasz M. , Adamska Dorota , Kosinska Joanna , Dziembowski Andrzej
Published: August 2015

Human DIS3, the nuclear catalytic subunit of the exosome complex, contains exonucleolytic and endonucleolytic active domains. To identify DIS3 targets genome-wide, we combined comprehensive transcriptomic analyses of engineered HEK293 cells that expressed mutant DIS3, with Photoactivatable Ribonucleoside-Enhanced Cross-Linking and Immunoprecipitation (PAR-CLIP) experiments. In cells expressing DIS3 with both catalytic sites mutated, RNAs originating from unannotated genomic regions increased ∼2.5-fold, covering ∼70% of the genome and allowing for thousands of novel transcripts to be discovered. Previously described pervasive transcription products, such as Promoter Upstream Transcripts (PROMPTs), accumulated robustly upon DIS3 dysfunction, representing a significant fraction of PAR-CLIP reads. We have also detected relatively long putative premature RNA polymerase II termination products of protein-coding genes whose levels in DIS3 mutant cells can exceed the mature mRNAs, indicating that production of such truncated RNA is a common phenomenon. In addition, we found DIS3 to be involved in controlling the formation of paraspeckles, nuclear bodies that are organized aroundNEAT1lncRNA, whose short form was overexpressed in cells with mutatedDIS3. Moreover, theDIS3mutations resulted in misregulation of expression of ∼50% of transcribed protein-coding genes, probably as a secondary effect of accumulation of various noncoding RNA species. Finally, cells expressing mutant DIS3 accumulated snoRNA precursors, which correlated with a strong PAR-CLIP signal, indicating that DIS3 is the main snoRNA-processing enzyme. EXOSC10 (RRP6) instead controls the levels of the mature snoRNAs. Overall, we show that DIS3 has a major nucleoplasmic function in shaping the human RNA polymerase II transcriptome.
Regulation of alternative splicing in Drosophila by 56 RNA binding proteins
Authors: Brooks Angela N. , Duff Michael O. , May Gemma , Yang Li , Bolisetty Mohan , Landolin Jane , Wan Ken , Sandler Jeremy , Booth Benjamin W. , Celniker Susan E. , Graveley Brenton R. , Brenner Steven E.
Published: August 2015

Alternative splicing is regulated by RNA binding proteins (RBPs) that recognize pre-mRNA sequence elements and activate or repress adjacent exons. Here, we used RNA interference and RNA-seq to identify splicing events regulated by 56 Drosophila proteins, some previously unknown to regulate splicing. Nearly all proteins affected alternative first exons, suggesting that RBPs play important roles in first exon choice. Half of the splicing events were regulated by multiple proteins, demonstrating extensive combinatorial regulation. We observed that SR and hnRNP proteins tend to act coordinately with each other, not antagonistically. We also identified a cross-regulatory network where splicing regulators affected the splicing of pre-mRNAs encoding other splicing regulators. This large-scale study substantially enhances our understanding of recent models of splicing regulation and provides a resource of thousands of exons that are regulated by 56 diverse RBPs.