bluuebunny/crossref_metadata_2025 huggingface dataset:
Suicidal Behaviors Among Adolescents – The Role of School and Home Environment
Authors: Badr Hanan El-Sayed
Published: September 2016

Abstract. Aim: This study aimed to determine the prevalence of suicidal behaviors (ideation, planning, and attempts) among adolescents aged 13–16, and to identify psychosocial correlates of suicidal behaviors. Method: The 2010 Kuwait Global School-Based Student Health Survey (GSHS) cross-sectional study employed a two-stage cluster sample design targeting a representative sample of 2,672 students. A weighting factor was applied to make inferences to all students of the same age. Students' suicidal behaviors were the focus of this paper. Results: The prevalence rates of suicide ideation, planning, and attempts were 20.0% (95% CI = 18.5–21.6%), 14.0% (95% CI = 12.7–15.4%), and 18.1% (95% CI = 16.6–19.5%), respectively. About 26% of adolescents reported at least one suicidal behavior, while 8.5% experienced all three suicidal behaviors. Multivariate analysis revealed that girls, smoking, physical violence, feeling lonely, exposure to bullying at school, and having nonempathetic parents were significant correlates of the experience of suicidal behaviors among adolescents. Moreover, suicidal ideation stood out as a predictor of attempting suicide more than suicidal planning in both the total population and separately by gender. Conclusion: The prevalence of suicidal behaviors was alarmingly high among Kuwaiti adolescents. Adverse school and home environments strongly contributed to such behaviors. School-based mental health programs are necessary to reduce these life-threatening behaviors in Kuwait.
Evolution by flight and fight: diverse mechanisms of adaptation by actively motile microbes
Authors: Rendueles Olaya , Velicer Gregory J
Published: September 2016

Evolutionary adaptation can be achieved by mechanisms accessible to all organisms, including faster growth and interference competition, but self-generated motility offers additional possibilities. We tested whether 55 populations of the bacterium Myxococcus xanthus that underwent selection for increased fitness at the leading edge of swarming colonies adapted by swarming faster toward unused resources or by other means. Populations adapted greatly but diversified markedly in both swarming phenotypes and apparent mechanisms of adaptation. Intriguingly, although many adapted populations swarm intrinsically faster than their ancestors, numerous others do not. Some populations evolved interference competition toward their ancestors, whereas others gained the ability to facultatively increase swarming rate specifically upon direct interaction with ancestral competitors. Our results both highlight the diverse range of mechanisms by which actively motile organisms can adapt evolutionarily and help to explain the high levels of swarming-phenotype diversity found in local soil populations of M. xanthus.
Methylation of SFRP2 gene as a promising noninvasive biomarker using feces in colorectal cancer diagnosis: a systematic meta-analysis
Authors: Yang Qihua , Huang Tao , Ye Guoliang , Wang Bojun , Zhang Xinjun
Published: September 2016

Methylation of secreted frizzled-related protein genes (SFRP) associated with the Wnt signaling pathway has previously been reported. However, the diagnostic role of SFRP methylation in colorectal cancer (CRC) remains unclear. A systematic search was performed to identify eligible articles for analysis. The pooled OR showed that SFRP1, SFRP2, SFRP4 and SFRP5 methylation was significantly higher in CRC and benign mucosal lesions than in normal colonic mucosa. When CRC was compared to benign mucosal lesions, SFRP1 and SFRP2 methylation had a significantly higher OR, but methylated SFRP4 and SFRP5 had a similar OR. Moreover, the pooled sensitivity, specificity and AUC (area under the curve) of methylated SFRP2 in feces of patients with CRC vs. healthy subjects was 0.71, 0.94 and 0.94, respectively. Therefore, methylation of SFRP1 and SFRP2 may be significantly correlated with CRC. However, in a study with small sample size, methylated SFRP4 and SFRP5 were not shown to be closely associated with CRC. Additionally, detection of SFRP2 methylation in feces presents a potential noninvasive biomarker for CRC diagnosis.
Ultrahigh Responsivity-Bandwidth Product in a Compact InP Nanopillar Phototransistor Directly Grown on Silicon
Authors: Ko Wai Son , Bhattacharya Indrasen , Tran Thai-Truong D. , Ng Kar Wei , Adair Gerke Stephen , Chang-Hasnain Connie
Published: September 2016

Highly sensitive and fast photodetectors can enable low power, high bandwidth on-chip optical interconnects for silicon integrated electronics. III-V compound semiconductor direct-bandgap materials with high absorption coefficients are particularly promising for photodetection in energy-efficient optical links because of the potential to scale down the absorber size, and the resulting capacitance and dark current, while maintaining high quantum efficiency. We demonstrate a compact bipolar junction phototransistor with a high current gain (53.6), bandwidth (7 GHz) and responsivity (9.5 A/W) using a single crystalline indium phosphide nanopillar directly grown on a silicon substrate. Transistor gain is obtained at sub-picowatt optical power and collector bias close to the CMOS line voltage. The quantum efficiency-bandwidth product of 105 GHz is the highest for photodetectors on silicon. The bipolar junction phototransistor combines the receiver front end circuit and absorber into a monolithic integrated device, eliminating the wire capacitance between the detector and first amplifier stage.
Prediction of prostate cancer recurrence using quantitative phase imaging: Validation on a general population
Authors: Sridharan Shamira , Macias Virgilia , Tangella Krishnarao , Melamed Jonathan , Dube Emily , Kong Max Xiangtian , Kajdacsy-Balla André , Popescu Gabriel
Published: September 2016

Prediction of biochemical recurrence risk of prostate cancer following radical prostatectomy is critical for determining whether the patient would benefit from adjuvant treatments. Various nomograms exist today for identifying individuals at higher risk for recurrence; however, an optimistic under-estimation of recurrence risk is a common problem associated with these methods. We previously showed that anisotropy of light scattering measured using quantitative phase imaging, in the stromal layer adjacent to cancerous glands, is predictive of recurrence. That nested-case controlled study consisted of specimens specifically chosen such that the current prognostic methods fail. Here we report on validating the utility of optical anisotropy for prediction of prostate cancer recurrence in a general population of 192 patients, with 17% probability of recurrence. Our results show that our method can identify recurrent cases with 73% sensitivity and 72% specificity, which is comparable to that of CAPRA-S, a current state of the art method, in the same population. However, our results show that optical anisotropy outperforms CAPRA-S for patients with Gleason grades 7–10. In essence, we demonstrate that anisotropy is a better biomarker for identifying high-risk cases, while Gleason grade is better suited for selecting non-recurrence. Therefore, we propose that anisotropy and current techniques be used together to maximize prediction accuracy.
A novel affinity-based method for the isolation of highly purified extracellular vesicles
Authors: Nakai Wataru , Yoshida Takeshi , Diez Diego , Miyatake Yuji , Nishibu Takahiro , Imawaka Naoko , Naruse Ken , Sadamura Yoshifusa , Hanayama Rikinari
Published: September 2016

Extracellular vesicles (EVs) such as exosomes and microvesicles serve as messengers of intercellular network, allowing exchange of cellular components between cells. EVs carry lipids, proteins and RNAs derived from their producing cells and have potential as biomarkers specific to cell types and even cellular states. However, conventional methods (such as ultracentrifugation or polymeric precipitation) for isolating EVs have disadvantages regarding purity and feasibility. Here, we have developed a novel method for EV purification by using Tim4 protein, which specifically binds the phosphatidylserine displayed on the surface of EVs. Because the binding is Ca2+-dependent, intact EVs can be easily released from Tim4 by adding Ca2+ chelators. Tim4 purification, which we have applied to cell conditioned media and biofluids, is capable of yielding EVs of a higher purity than those obtained using conventional methods. The lower contamination found in Tim4-purified EV preparations allows more EV-specific proteins to be detected by mass spectrometry, enabling better characterization and quantification of different EV populations’ proteomes. Tim4 protein can also be used as a powerful tool for quantification of EVs in both ELISA and flow cytometry formats. Thus, the affinity of Tim4 for EVs will find abundant applications in EV studies.
Genome-wide mapping of nucleosome positions in Saccharomyces cerevisiae in response to different nitrogen conditions
Authors: Zhang Peng , Du Guocheng , Zou Huijun , Xie Guangfa , Chen Jian , Shi Zhongping , Zhou Jingwen
Published: September 2016

Well-organized chromatin is involved in a number of various transcriptional regulation and gene expression. We used genome-wide mapping of nucleosomes in response to different nitrogen conditions to determine both nucleosome profiles and gene expression events in Saccharomyces cerevisiae. Nitrogen conditions influence general nucleosome profiles and the expression of nitrogen catabolite repression (NCR) sensitive genes. The nucleosome occupancy of TATA-containing genes was higher compared to TATA-less genes. TATA-less genes in high or low nucleosome occupancy, showed a significant change in gene coding regions when shifting cells from glutamine to proline as the sole nitrogen resource. Furthermore, a correlation between the expression of nucleosome occupancy induced NCR sensitive genes or TATA containing genes in NCR sensitive genes and nucleosome prediction were found when cells were cultured in proline or shifting from glutamine to proline as the sole nitrogen source compared to glutamine. These results also showed that variation of nucleosome occupancy accompany with chromatin-dependent transcription factor could influence the expression of a series of genes involved in the specific regulation of nitrogen utilization.
The effects of ordered carbon vacancies on stability and thermo-mechanical properties of V8C7 compared with VC
Authors: Chong XiaoYu , Jiang YeHua , Zhou Rong , Feng Jing
Published: September 2016

The ordered non-stoichiometric V8C7 can form in the VCy carbides by the disorder–order phase transformation. The intrusion of ordered carbon vacancies can affect their stability, mechanical, thermal and electronic properties. The relatively thermodynamic stability and mechanical properties at high temperature for the ordered stoichiometric VC and non-stoichiometric V8C7 are investigated in this paper by first-principle calculations combined with the quasi-harmonic approximation. The difference between the properties of VC and V8C7 can be obtained. We find that the V8C7 is thermodynamic more stable than VC, but has weaker elastic heat resistance than VC. Moreover, the minimum thermal conductivity of VC is a little larger than V8C7 and a simple way is proposed to characterize the anisotropy of lattice thermal conductivity based on the Cahill’s model.
SENP1 Is a Crucial Regulator for Cell Senescence through DeSUMOylation of Bmi1
Authors: Xia Nansong , Cai Juan , Wang Feifei , Dong Baijun , Liu Song , Chen Fengling , Cheng Jinke , Zuo Yong
Published: September 2016

Cell senescence can limit proliferative potential and prevent tumorigenesis. Bmi1 is a key regulator in cell senescence by suppressing the Ink4a/Arf locus. However, how to regulate Bmi1 activity in cell senescence is largely unknown. Here, we show that SENP1 plays an important role in cell senescence by regulating Bmi1 SUMOylation. Senp1−/− primary MEF cells show resistance to cell senescence induced by passaging or other senescence inducing signals. SENP1 deficiency also reduces oncogene H-RasV12-induced senescence, and enhances H-RasV12-induced cell transformation. We further show that in Senp1−/− MEFs the expression of p19Arf, an important regulator in p53/p21-mediated cell senescence, is markedly reduced. Meanwhile, we demonstrate that SENP1 can specifically de-SUMOylate Bmi1 and thereby decreases the occupancy of Bmi1 on p19Arf promoter leading to decrease of H2AK119 mono-ubiquitination and up-expression of p19Arf. These data reveal a crucial role of SENP1 in regulation of cell senescence as well as cell transformation.
Oligomannan Prebiotic Attenuates Immunological, Clinical and Behavioral Symptoms in Mouse Model of Inflammatory Bowel Disease
Authors: Ferenczi Szilamér , Szegi Krisztián , Winkler Zsuzsanna , Barna Teréz , Kovács Krisztina J.
Published: September 2016

Inflammatory bowel disease shows increasing prevalence, however its pathomechanism and treatment is not fully resolved. Prebiotics are non-digestible carbohydrates which might provide an alternative to treat inflammatory conditions in the gut due to their positive effects either on the microbiome or through their direct effect on macrophages and mucosa. To test the protective effects of an oligomannan prebiotic, yeast cell wall mannooligosaccharide (MOS) was administered in dextran-sulphate-sodium (DSS)-induced mouse model of acute colitis. MOS reduced DSS-induced clinical- (weight loss, diarrhea) and histological scores (mucosal damage) as well as sickness-related anxiety. DSS treatment resulted in changes in colon microbiome with selective increase of Coliform bacteria. MOS administration attenuated colitis-related increase of Coliforms, normalized colonic muc2 expression and attenuated local expression of proinflammatory cytokines IL-1a, IL1b, IL6, KC, G-CSF and MCP1 as well as toll-like receptor TLR4 and NLRP3 inflammasome. Some of the protective effects of MOS were likely be mediated directly through local macrophages because MOS dose-dependently inhibited IL-1b and G-CSF induction following in vitro DSS challenge and IL1a, IL1b, G-SCF- and IL6 increases after LPS treatment in mouse macrophage cell line RAW264.7. These results highlight oligomannan prebiotics as therapeutic functional food for testing in clinical trials.
Correlations between fluorescence emission and base stacks of nucleic acid G-quadruplexes
Authors: Gao Shang , Cao Yanwei , Yan Yuting , Xiang Xiaoxuan , Guo Xinhua
Published: September 2016

Correlations between parallel G-quadruplex structures and featured fluorescence emission bands have been built.
The ant and the elephant: ambient RF harvesting from the uplink
Authors: Mimis Konstantinos , Gibbins David R. , Dumanli Sema , Watkins Gavin T.
Published: September 2016

This work investigates the available ambient radio frequency (RF) power density in dynamic, outdoor environments with a specific focus in the uplink. A spectrum survey was carried out around Bristol, UK between 500 MHz and 3 GHz using a handheld spectrum analyser and an omnidirectional broadband discone antenna. Measurements were performed while walking, travelling in a car and on a train. The results are compared with baseline indoors measurements, and as expected, ambient RF power densities in the outdoor environments were significantly higher. Interestingly, in some cases the power contained in the uplink of cellular communication networks is shown to be a better energy source than the downlink. It was found that in a train during rush hour, there is 17 times the mean power density and 45 times the peak power density in the uplink compared with the downlink. This shows that there is scope for ambient energy harvesting in environments with a large density of user equipment. Finally, by accounting for the rectifier efficiency it is estimated that during the train commute between Bristol and Bath in the UK a total of 27.2 mJ of energy could be collected.
Compact CHMSIW filters with TZs
Authors: Huang Liwen , Cha Hao
Published: September 2016

Novel capacitively loaded half‐mode substrate integrated waveguide (CHMSIW) filters with transmission zeros (TZs) are presented in this study. The CHMSIW is proposed by embedding a metallic stripline and inductive post in the HMSIW, which introduces a series inductor‐capacitor (LC) branch circuit in waveguide thereby generating TZ above the passband. Furthermore, as the embedded stripline introduces additional capacitance, a significant size reduction can be achieved for the CHMSIW in comparison with conventional HMSIW. Two types of CHMSIW resonator topologies are developed by varying the number of LC branches, with multiple TZs achieved by inserting multiple LC branches in waveguide. On the basis of the CHMSIW resonators, compact bandpass filters are designed and fabricated, where TZs are obtained in the upper stopband and a sharp transition is achieved from the passband to the stopband. To further improve the selectivity, mixed coupling is introduced in CHMSIW filters to generate additional TZs in the lower stopband. A prototype of the mixed‐coupled CHMSIW filter is designed and tested, and high selectivity as well as compact size and good out‐of‐band rejection have been achieved for the proposed mixed‐coupled CHMSIW filter.
Compact circular waveguide TM02‐TE11 mode converter
Authors: Zhang Xinge , Li Shaofu
Published: September 2016

Using the concept of a metallic cylinder and a linearly tapered metallic baffle loaded in a circular waveguide to convert TM02 circular waveguide mode into TE11 circular waveguide mode, a novel and compact circular waveguide TM02‐TE11 mode converter is designed, fabricated, and measured. The detailed design methods, experimental setups and results are presented in this study. Simulation results show that the purity of output fundamental TE11 mode of the converter exceeds 99.6% for an operating frequency of 9.4 GHz and the power capability is as high as 1.66 GW, the mode conversion efficiency is more than 90% from 9.23 to 9.83 GHz band and the relative bandwidth is about 6.38%. A good agreement between measurements and simulations is observed. The circular waveguide TM02‐TE11 mode converter has many advantages, such as the simple structure, coaxial input and output, high conversion efficiency, proper bandwidth and high power‐handling capability. When used in the field of high power microwave transmission and radiation, the proposed converter could significantly enhance the compactness of all the radiation systems.
Active distribution power system with multi‐terminal DC links
Authors: Chen Dong , Xu Lie , Zhang Wendian
Published: September 2016

A fast power restoration operational scheme and relevant stabilising control is proposed for active distribution power systems with multi‐terminal DC network in replacement of the conventional normal open switches. A nine‐feeder benchmark distribution power system is established with a four‐terminal medium power DC system injected. The proposed power restoration scheme is based on the coordination among distributed control among relays, load switches, voltage source converters and autonomous operation of multi‐terminal DC system. A DC stabiliser is proposed with virtual impedance method to damp out potential oscillation caused by constant power load terminals. The proposed system and controls are validated by frequency domain state‐space model and time‐domain case study with Matlab/Simulink.
A universal property for sequential measurement
Authors: Westerbaan Abraham , Westerbaan Bas
Published: September 2016

We study the sequential product the operation p∗q=pqp on the set of effects, [0, 1]𝒜, of a von Neumann algebra 𝒜 that represents sequential measurement of first p and then q. In their work [J. Math. Phys. 49(5), 052106 (2008)], Gudder and Latrémolière give a list of axioms based on physical grounds that completely determines the sequential product on a von Neumann algebra of type I, that is, a von Neumann algebra ℬ(ℋ) of all bounded operators on some Hilbert space ℋ. In this paper we give a list of axioms that completely determines the sequential product on all von Neumann algebras simultaneously (Theorem 4).
State-resolved dynamics study of the H + HS reaction on the 3A′ and 3A″ states with time-dependent quantum wave packet method
Authors: Wu Hui , Duan Zhi-Xin , Yin Shu-Hui , Zhao Guang-Jiu
Published: September 2016

The quantum dynamics calculations of the H + HS (v = 0, j = 0) reaction on the 3A′ and 3A″ potential energy surfaces (PESs) are performed using the reactant coordinate based time-dependent wave packet method. State-averaged and state-resolved results for both channels of the title reaction are presented in the 0.02-1.0 eV collision energy range and compared with those carried out with quasi-classical trajectory (QCT) method. Total integral cross sections (ICSs) for both channels are in excellent agreement with previous quantum mechanical (QM)-Coriolis coupling results while poorly agree with the QCT ICSs of the exchange channel, particularly near the threshold energy region. The product rotational distributions show that for the abstraction channel, the agreement between our QM and the QCT results improves with increasing collision energy. For the exchange channel, our calculations predict colder rotational distributions as compared to those obtained by QCT calculations. Although the QM total differential cross sections (DCSs) are in qualitatively good agreement with the QCT results, the two sets of the state-to-state DCSs with several peaks exhibit great divergences. The origin of the divergences are traced by analyzing the QM DCS for the H + HS (v = 0, j = 0) → H2 (v′ = 0, j′ = 0) + S reaction on the 3A″ PES at Ec = 1.0 eV. It is discovered that several groups of J partial waves are involved in the reaction and the shape of the DCS is greatly altered by quantum interferences between them.
Phase-dependent ultrafast third-order optical nonlinearities in metallophthalocyanine thin films
Authors: Kumar Samir , Anil Kumar K. V. , Dharmaprakash S. M. , Das Ritwick
Published: September 2016

We present a comprehensive study on the impact of phase transformations of metallophthalocyanine thin films on their third-order nonlinear optical (NLO) properties. The metallophthalocyanine thin films are prepared by thermally evaporating the commercially available Copper(II)2,9,16,23-Tetra-tert-butyl-29H,31H-phthalocyanine (CuPc) and Zinc(II) 2,9,16,23-Tetra-tert-butyl-29H,31H-phthalocyanine (ZnPc) powder on glass substrate. Thermal annealing causes a phase transformation which has a distinct signature in powder X-ray diffraction and UV-Vis-NIR spectroscopy. The NLO characteristics which include nonlinear refractive index n2, as well as nonlinear absorption coefficient (βeff), were measured by using a single beam Z-scan technique. An ultrashort pulsed fiber laser emitting femtosecond pulses (Δτ ≈ 250 fs) at 1064 nm central wavelength is used as a source for the Z-scan experiment. The βeff values in as prepared thin films were ascertained to be smaller as compared to the annealed one due to the smaller value of saturation intensity (Is) which, in turn, is a consequence of ground-state bleaching in the thermally unstable amorphous state of the molecule. Interestingly, the nonlinear refractive indices bear opposite sign for CuPc and ZnPc. The variations in the third-order nonlinearity in CuPc and ZnPc are discussed in terms of molecular packing and geometries of metallophthalocyanine molecules.
Intensity modulated optical transmission in a non-linear dielectric environment with an embedded mono-layer transition metal dichalcogenide
Authors: Sengupta Parijat , Bellotti Enrico
Published: September 2016

We study the optical behavior of an arrangement in which the interface between a linear and non-linear dielectric media is covered by an embedded mono-layer of transition metal dichalcogenides (TMDC). The optical behavior is qualitatively obtained through transmission and reflection coefficients which are a function of the third order non-linear susceptibility of the Kerr-type dielectric and the inter-band optical conductivity of the TMDC mono-layer. The inter-band optical conductivity of the TMDC mono-layer is calculated using the Kubo formalism from the linear response theory. In particular, we theoretically demonstrate that the optical response of this structure can be switched between the total internal reflection and a normal transmission regime by controlling the intensity of the incident radiation. The reflection and transmission functions are shown to be amenable to further control by altering the inter-band optical conductivity of the embedded TMDC mono-layer. The optical conductivity is directly related to its energy dispersion. We specifically choose two TMDC mono-layers, MoS2 and WSe2, which have nearly identical dispersion parameters apart from a much stronger spin-orbit coupling in the latter. The stronger spin-orbit coupling in WSe2 does not significantly alter the inter-band optical conductivity to manifest as an enhanced reflection spectrum. However, we find that application of an external perturbation such as strain could be effectively used to modulate the overall optical response. We conclude by discussing briefly the phenomenon of optical bistability which arises in materials exhibiting optical non-linearity via an intensity-dependent refractive index.
Optimization and application of cooled avalanche photodiodes for spectroscopic fluctuation measurements with ultra-fast charge exchange recombination spectroscopy
Authors: Truong D. D. , Fonck R. J. , McKee G. R.
Published: September 2016

The Ultra-Fast Charge Exchange Recombination Spectroscopy (UF-CHERS) diagnostic is a highly specialized spectroscopic instrument with 2 spatial channels consisting of 8 spectral channels each and a resolution of ∼0.25 nm deployed at DIII-D to measure turbulent ion temperature fluctuations. Charge exchange emissions are obtained between 528 and 530 nm with 1 μs time resolution to study plasma instabilities. A primary challenge of extracting fluctuation measurements from raw UF-CHERS signals is photon and electronic noise. In order to reduce dark current, the Avalanche Photodiode (APD) detectors are thermo-electrically cooled. State-of-the-art components are used for the signal amplifiers and conditioners to minimize electronic noise. Due to the low incident photon power (≤1 nW), APDs with a gain of up to 300 are used to optimize the signal to noise ratio. Maximizing the APDs’ gain while minimizing the excess noise factor (ENF) is essential since the total noise of the diagnostic sets a floor for the minimum level of detectable broadband fluctuations. The APDs’ gain should be high enough that photon noise dominates electronic noise, but not excessive so that the ENF overwhelms plasma fluctuations. A new generation of cooled APDs and optimized preamplifiers exhibits significantly enhanced signal-to-noise compared to a previous generation. Experiments at DIII-D have allowed for characterization and optimization of the ENF vs. gain. A gain of ∼100 at 1700 V is found to be near optimal for most plasma conditions. Ion temperature and toroidal velocity fluctuations due to the edge harmonic oscillation in quiescent H-mode plasmas are presented to demonstrate UF-CHERS’ capabilities.
Enhanced superconductivity by strain and carrier-doping in borophene: A first principles prediction
Authors: Xiao R. C. , Shao D. F. , Lu W. J. , Lv H. Y. , Li J. Y. , Sun Y. P.
Published: September 2016

By first principles calculations, we predict that the recently prepared borophene is a pristine two-dimensional monolayer superconductor in which the superconductivity can be significantly enhanced by strain and charge carrier doping. The intrinsic metallic ground state with high density of states at Fermi energy and strong Fermi surface nesting lead to sizeable electron-phonon coupling, making the freestanding borophene superconduct with Tc close to 19.0 K. The tensile strain can increase the Tc to 27.4 K, while the hole doping can notably increase Tc to 34.8 K. The results indicate that the borophene grown on substrates with large lattice parameters or under photoexcitation can show enhanced superconductivity with Tc far above the liquid hydrogen temperature of 20.3 K, which will largely broaden the applications of such promising material.
Parametric study of H-Darrieus vertical-axis turbines using CFD simulations
Authors: Gosselin Rémi , Dumas Guy , Boudreau Matthieu
Published: September 2016

A parametric study of vertical axis turbines of the H-Darrieus type is conducted using state-of-the-art Computational Fluid Dynamics (CFD) and the k-ω Shear Stress Transport RANS model in its unsteady form. Although most parameters have previously been investigated individually, the effect of solidity, number of blades, tip speed ratio, Reynolds number, fixed blade pitch angle, and blade thickness on the aerodynamic efficiency of the turbine is evaluated using the same performance evaluation set-up in order to determine what would be the best aerodynamic configuration and operation parameter in a given application. The quantitative impact of 3D effects associated with the blade aspect ratio and the use of end-plates is also investigated. For high-Reynolds applications, optimal radius-based solidity is found to be around σ=0.2, while higher solidities show a lower maximum efficiency than what was previously published using simpler streamtube based methods. In 3D, a small blade aspect ratio (AR=7) leads to a relative efficiency drop of nearly 60% compared to the 2D prediction. Longer blades improve the 3D efficiency greatly. End-plates are found to have a positive effect on power extraction performances, as long as their size and thus their drag are limited.
Charged particle dynamics in the presence of non-Gaussian Lévy electrostatic fluctuations
Authors: Moradi Sara , del-Castillo-Negrete Diego , Anderson Johan
Published: September 2016

Full orbit dynamics of charged particles in a 3-dimensional helical magnetic field in the presence of α-stable Lévy electrostatic fluctuations and linear friction modeling collisional Coulomb drag is studied via Monte Carlo numerical simulations. The Lévy fluctuations are introduced to model the effect of non-local transport due to fractional diffusion in velocity space resulting from intermittent electrostatic turbulence. The probability distribution functions of energy, particle displacements, and Larmor radii are computed and showed to exhibit a transition from exponential decay, in the case of Gaussian fluctuations, to power law decay in the case of Lévy fluctuations. The absolute value of the power law decay exponents is linearly proportional to the Lévy index α. The observed anomalous non-Gaussian statistics of the particles' Larmor radii (resulting from outlier transport events) indicate that, when electrostatic turbulent fluctuations exhibit non-Gaussian Lévy statistics, gyro-averaging and guiding centre approximations might face limitations and full particle orbit effects should be taken into account.
High-resolution, high-linearity temperature sensor using surface acoustic wave device based on LiNbO3/SiO2/Si substrate
Authors: Tian Xiang-Guang , Liu Heng , Tao Lu-Qi , Yang Yi , Jiang Hanjun , Ren Tian-Ling
Published: September 2016

A high-resolution and high-linearity surface acoustic wave (SAW) temperature sensor, consisting of a SAW resonator device fabricated on novel X-cut LiNbO3/SiO2/Si piezoelectric substrate and a resonance frequency readout chip using standard 180 nm CMOS technology, is presented for the first time. High temperature performance substrate LiNbO3/SiO2/Si is prepared mainly by ion implantation and wafer bonding at first. RF SAW device with resonance frequency near 900 MHz is designed and fabricated on the substrate. Traditional probe method using network analyzer and the readout chip method are both implemented to characterize the fabricated SAW device. Further measurement of temperature using resonance frequency shift of SAW device demonstrates the feasibility of the combined system as a portable SAW temperature sensor. The obtained frequency-temperature relation of the fabricated device is almost linear. The frequency resolution of the readout chip is 733 Hz and the corresponding temperature accuracy is 0.016 ° C. Resolution of the sensor in this work is superior to most of the commercial temperature measurement sensors. Theory analysis and finite element simulation are also presented to prove the mechanism and validity of using SAW device for temperature detection applications. We conclude that the high-linearity frequency-temperature relation is achieved by the offset between high-order coefficients of LiNbO3 and SiO2 with opposite signs. This work offers the possibility of temperature measuring in ultra-high precision sensing and control applications.
Proper hygiene and effective management of livestock as a panacea for agricultural development and increase in Nigeria's gross domestic product (GDP): a review.
Authors: Kwaghe A. V. , Vakuru C. T. , Ndahi M. D. , Abubakar A. , Iwar V. N. , Eze E.
Published: September 2016

Increased livestock production and better food security will naturally follow from proper livestock management practices. Such management practices include the application of appropriate vaccination schedule, biosecurity, feeding regimen, and implementation and sustenance of improved and feasible livestock policies. In meat production, the abattoir needs to be well equipped for antemortem and postmortem procedures, hygienic processing of carcasses, and packaging, to improve the quality and quantity of meat and meat products. In Nigeria, about 90% of the livestock industry (cattle, sheep and goats) is managed extensively (nomadic management system) or semi-intensively (animals are taken out to graze and are brought home with little or no provision at home). These systems are greatly affected by insufficient grazing reserves, lack of cattle routes, and consequently, by conflicts between the livestock farmers and crop farmers due to invasion of livestock into farms during grazing. During the dry season, livestock animals tend to become emaciated due to insufficient food, which leads to health depreciation due to declined immune status, and decline in meat production and reproduction rate. Diseases possess a great challenge to meat and egg production due to illiteracy and lack of resources for proper management of livestock. In the poultry industry, where most of the meat is produced, typically no or only some biosecurity procedures are in place at the commercial farms. The backyard local poultry are kept without any form of care; they tend to scavenge for their food and are prone to all forms of diseases, parasites and predators. The hygienic status and carcass preparation at Nigeria's abattoirs is very poor, which affects the meat industry. In general, livestock production in the country is greatly affected by poor management practices, diseases and poor meat processing strategies, which leads to the production of low-quality meat that can easily decompose, and the spread of food-borne and zoonotic diseases. Livestock policies in the country have not produced the desired economic growth due to their inadequate implementation. Also, the oil boom era relegated agriculture to the background from being the major part of the nation's gross domestic product (GDP). There is need for new strategies and proper implementation of livestock policies - it is recommended to encourage stakeholders to participate and to diversify the industry into manufacturing and not just production. This study was carried out in order to assess state of livestock production, management systems including assessment of livestock policies, and challenges faced by this industry in Nigeria, and to identify the way forward for better livestock production and subsequent increase in the nation's GDP.
Evolution of an academic career: DML’s influence
Authors: Mandeville Tom
Published: September 2016

When I first met Don, I was already an established research fellow in regional economics. Don’s subsequent influence directly helped me follow my dreams, passions and interests. Thus, my academic career grew, developed and transformed from regional economics, to information economics, and eventually to evolutionary economics. This reflection traces that evolving process, illustrating Don’s influence throughout.
PSSV: a novel pattern-based probabilistic approach for somatic structural variation identification
Authors: Chen Xi , Shi Xu , Hilakivi-Clarke Leena , Shajahan-Haq Ayesha N , Clarke Robert , Xuan Jianhua
Published: September 2016

Motivation

Whole genome DNA-sequencing (WGS) of paired tumor and normal samples has enabled the identification of somatic DNA changes in an unprecedented detail. Large-scale identification of somatic structural variations (SVs) for a specific cancer type will deepen our understanding of driver mechanisms in cancer progression. However, the limited number of WGS samples, insufficient read coverage, and the impurity of tumor samples that contain normal and neoplastic cells, limit reliable and accurate detection of somatic SVs.

Results

We present a novel pattern-based probabilistic approach, PSSV, to identify somatic structural variations from WGS data. PSSV features a mixture model with hidden states representing different mutation patterns; PSSV can thus differentiate heterozygous and homozygous SVs in each sample, enabling the identification of those somatic SVs with heterozygous mutations in normal samples and homozygous mutations in tumor samples. Simulation studies demonstrate that PSSV outperforms existing tools. PSSV has been successfully applied to breast cancer data to identify somatic SVs of key factors associated with breast cancer development.

Availability and Implementation

An R package of PSSV is available at http://www.cbil.ece.vt.edu/software.htm.

Supplementary information

Supplementary data are available at Bioinformatics online.
5 Minute Teaching Time Outs: A String of Teaching Pearls
Authors: Patel Silka , Bienstock Jessica , White-Prock Paula , Smith Dora , Burrell Dayna , Chou Betty
Published: September 2016

BACKGROUND:

Incorporating didactics designed to improve teaching skills into departmental agenda is challenging but necessary. Often lectures take place once a year with little continuing reinforcement. Five Minute Teaching Time Outs (5MTTO) were created to introduce and reinforce important teaching skills to all levels of educators. The goal was to incorporate them into routine departmental activities such as M&M/Grand Rounds.

METHODS:

A multicenter prospective survey was conducted to assess faculty, fellow and resident attitudes towards the 5MTTO. Six-5MTTOs were created to cover a broad range of teaching topics. These were presented over the year at routinely scheduled department meetings. Participants were asked to fill out an anonymous survey at the completion of each 5MTTO.

RESULTS:

On average 45 participants were present at each 5MTTO among the 3 institutions, usually evenly split between faculty/fellows and residents. On average, after each session, participants agreed/strongly agreed that material from the individual 5MTTOs would influence their teaching approach 82–97% of the time. Over 92% of the time participants agreed/strongly agreed that 5 minutes was adequate and over 93% agreed/strongly agreed to having future 5MTTO.

DISCUSSION:

Incorporating teaching skills into departmental activities can be difficult due to time constraints. Regular reinforcement is as important for educators as it is for learners. These 5MTTO are well-received by the department, fit into already scheduled activities and may influence the teaching behaviors of our clinician-educators.
Integrating Basic Science Into a Senior Medical Student Residency Preparation Elective
Authors: Malone Anita , Stein Tamara , Marzano David , Skinner Bethany , Hammoud Maya , Morgan Helen
Published: September 2016

BACKGROUND:

Increasing medical student residency preparedness is an important current initiative in medical education. Demonstrating knowledge of abdominal and pelvic anatomy is a vital level 1 milestone. Anatomy is typically taught early in medical school, and multiple studies have demonstrated that there is a significant decline in anatomical knowledge throughout medical school. Residency preparation electives are an optimal time for integrating anatomical teaching in relevant clinical and surgical contexts.

METHODS:

In 2014 and 2015, 27 senior medical students matching into OBGYN residency participated in a 4-week Advanced Clinical Skills in OBGYN. Two half-day sessions were dedicated to reviewing pelvic viscera, vasculature and nerve supply, and perineal anatomy using embalmed cadavers. Clinical correlations were emphasized throughout dissection. Two half-days consisted of operative procedures performed on fresh-frozen cadavers. Anatomical knowledge was assessed with pre- and post-course multiple choice assessment. Statistical analysis consisted of paired t tests. Student satisfaction was assessed with a web-based survey.

RESULTS:

Anatomical knowledge scores increased significantly from 64.8% (SD=1.99) to 83.6% (SD=1.63), P<.01. On a 5 point scale (1=Strongly Disagree, 5=Strongly Agree) when asked if the sessions were “relevant to their education” and “made them feel more prepared for residency,” students' average responses were 4.93 and 4.89, respectively.

DISCUSSION:

We need to better prepare senior medical students for obstetrics and gynecology residency. This purposeful and innovative approach to improving preparedness for residency improved anatomical knowledge, with very high student satisfaction ratings.
Residents' Insight on Student Mistreatment: What We Learned From Our First Action Research Cycle
Authors: Galey Hannah , Thompson Amy , Bennett Aurora , Flood-Shaffer Kellie , Wagner Emily
Published: September 2016

BACKGROUND:

The medical student mistreatment literature focuses on prevalence, risk factors, and mistreatment sources. Studies describe interventions to improve learning culture, however many students continue to report mistreatment. We initiated a project to engage residents to construct knowledge of the mistreatment phenomenon, plan, and evaluate actions to address this problem.

METHODS:

Action research (AR) is a repetitive, cyclical, participatory research process. We used the method of Group Level Assessment (GLA) to organize our first AR cycle. In a group setting, residents responded individually to 22 theoretically-derived prompts. Residents viewed all responses, performed first-cut qualitative analysis, and planned actions from group discussion. Secondary qualitative analysis was performed to understand mistreatment characteristics, contributing factors, responses and outcomes, and interventions.

RESULTS:

Twenty-three residents participated. Factors identified that contributed to student mistreatment included different medical specialty paths, unprepared students, poorly defined expectations, hierarchy, poor communications, and residents' need for patience, time and inspiration to teach. Residents acknowledged both negative and positive outcomes from humiliation, including loss of focus, learner withdrawal, positive resilience traits, motivation to learn, and attention to details. Solutions spanned clinical and educational interventions to needed gains in personal insight and improved behaviors.

DISCUSSION:

Our findings confirm the influence of previously described factors contributing to medical student mistreatment. Most importantly, we gained significant insight into local factors contributing to this phenomenon. Residents are now organizational change-makers, an AR principle. As a result, we are implementing resident-inspired interventions and moving forward with our next AR cycle.
Smart Phone-Based Quick Response (QR) Evaluations for Residents: What Do Faculty Think?
Authors: Debiec Katherine , Sobhani Nasim , Fay Emily , Stephenson-Famy Alyssa , Schiff Melissa
Published: September 2016

BACKGROUND:

Providing ample, high quality and timely venue-based evaluations of resident performance is a critical mandate of graduate medical education.

METHODS:

We utilized a before and after study design to compare a paper venue-based evaluation tool for procedures to a smart phone QR evaluation tool introduced in July 2014 at the University of Washington OB-GYN Residency Program. Each resident was assigned a QR code for faculty to access the evaluation in a smart-phone based application. Faculty completed a baseline survey evaluating the paper tool and a 6-month follow-up survey evaluating the QR tool. We compared characteristics of the feedback and the evaluation tools using Wilcoxon signed rank test.

RESULTS:

Twenty-three of 40 (58%) eligible teaching faculty 40 completed surveys at 0 and 6 months after introducing the QR tool. More faculty (57.1%) agreed that the QR tool promoted interaction compared to the paper tool (13.0%, P=.0005). More faculty (85.7%) felt comfortable approaching residents with the QR tool compared with paper (34.8%, P=.0019) and more felt that the QR tool (52.4%) helped give feedback for residents (17.4%, P=.0071). Greater percentage of faculty (71.4%) provided feedback within 24 hours with the QR tool compared with paper (17.4%, P=.0005).

DISCUSSION:

Faculty are comfortable utilizing smart phone-based QR technology for resident evaluation and it appears to be associated with more timely feedback.
Development and Validation of Mental Practice as a Training Strategy for Abdominal Hysterectomy
Authors: Salva Catherine , Saab Said , Dayaratna Sandra , Hutton Ellyn , Bastek Jamie
Published: September 2016

Local Mentor: Lorraine Dugoff, MD

APGO Advisor: Alice R. Goepfert, MD

PURPOSE:

To develop and validate a Mental Practice tool for resident training in abdominal hysterectomy.

BACKGROUND:

Abdominal hysterectomy is a common operation performed by obstetrician-gynecologists. Training opportunities for this procedure are diminishing due to many factors. Mental Practice (the use of mental imagery to rehearse a task symbolically before performance) has been used successfully in sports and music to enhance skill. This strategy demonstrates benefit in existing surgical education literature.

METHODS:

A Mental Practice script was developed by taking expert surgeons through a cognitive walk-through to identify key procedural cues. For validation, resident and attending gynecologic surgeons mentally rehearsed abdominal hysterectomy. Ability to mentally practice this procedure was assessed before and after exposure to the tool. We used a validated 7-point Likert scale questionnaire composed of 8 questions (MIQ: Mental Imagery Questionnaire, 56 points).

EVALUATION:

The study included 16 subjects, with experience ranging from 0 to >100 procedures. Reliability testing of the questionnaire (Cronbach alpha 0.915 before Mental Practice training and 0.933 after) indicated internal consistency. Construct validity was also supported. Significant improvement in MIQ score after use of the tool was shown by residents (39 versus 44; P=.003). Attending scores also improved but not significantly (54 versus 55; P=.066), suggesting a ceiling effect. A linear relationship was evident between the benefit of the tool and experience (P=.051).

DISSEMINATION:

A larger study is planned to determine the effect of mental practice on surgical performance for residents.

REFLECTIVE CRITIQUE:

The tool was most useful for trainees with the least surgical experience.