bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyclic stretch-induced Crp3 sensitizes vascular smooth muscle cells to apoptosis during vein arterialization remodeling
Authors: Campos Luciene Cristina Gastalho , Ribeiro-Silva João Carlos , Menegon Alessandra Santos , Barauna Valerio Garrone , Miyakawa Ayumi Aurea , Krieger Jose Eduardo
Published: February 2018

Vein graft failure limits the long-term patency of the saphenous vein used as a conduit for coronary artery bypass graft. Early graft adaptation involves some degree of intima hyperplasia to sustain the hemodynamic stress, but the progress to occlusion in some veins remains unclear. We have demonstrated that stretch-induced up-regulation of cysteine and glycine-rich protein 3 (Crp3) in rat jugular vein and human saphenous vein in response to arterialization. Here, we developed a Crp3-knockout (KO) rat to investigate the role of Crp3 in vascular remodeling. After 28 days of jugular vein arterialization, the intima layer was three-fold thicker in the Crp3-KO that showed comparable smooth muscle cells (SMC) proliferation but an absence of early apoptosis observed in the wild-type (WT) rat. We then investigated the role of Crp3 in early integrin-mediated signaling apoptosis in isolated jugular SMC. Interestingly, under basal conditions, ceramide treatment failed to induce apoptosis in both WT and Crp3-KO SMC. Under stretch, Crp3 expression increased in WT SMC and ceramide-induced apoptosis. Immunoblotting analysis indicated that ceramide stretch-induced apoptosis in SMC is accompanied by a decrease in the phosphorylation status of both focal adhesion kinase (Fak) and protein kinase B (Akt), leading to an increase in Bax expression and caspase-3 cleavage. In contrast, ceramide failed to decrease Fak and Akt phosphorylation in Crp3-KO SMC and, therefore, there was no downstream induction of Bax expression and effector caspase-3 cleavage. Taken together, we provide evidence that stretch-induced Crp3 modulates vein remodeling in response to arterialization by sensitizing SMC to apoptosis.
MicroED: a versatile cryoEM method for structure determination
Authors: Nannenga Brent L. , Gonen Tamir
Published: February 2018

Micro-electron diffraction, or MicroED, is a structure determination method that uses a cryo-transmission electron microscope to collect electron diffraction data from nanocrystals. This technique has been successfully used to determine the high-resolution structures of many targets from crystals orders of magnitude smaller than what is needed for X-ray diffraction experiments. In this review, we will describe the MicroED method and recent structures that have been determined. Additionally, applications of electron diffraction to the fields of small molecule crystallography and materials science will be discussed.
Effective scaling registration approach by imposing emphasis on scale factor
Authors: Xu Siyu , Zhu Jihua , Li Yaochen , Wang Jun , Lu Huimin
Published: February 2018

This Letter proposes an effective approach for the scaling registration of point sets. By imposing the emphasis on the scale factor, the authors design a novel objective function, which can avoid the phenomenon that the scale factor converges to zero. Subsequently, the well‐designed function is optimised by the proposed scaling iterative closest point algorithm, which can calculate the optimal scaling transformation by iterations. The proposed approach is validated on public data sets, demonstrating its superiority over previous approaches on efficiency and robustness.
Circuit elements influence on optimal number of phases of DC/DC buck converter
Authors: Kováč D. , Bereš M. , Kováčová I. , Vince T. , Molnár J. , Dziak J. , Jacko P. , Bučko R. , Tomčíková I. , Schweiner D.
Published: February 2018

The letter deals with the methodology for determining the optimal number of phases of a multi‐phase DC to DC buck converter from the point of view of its maximum efficiency. It also analyses the impact of individual parameters of the converter and the used components on the number of these phases.
New channel quality metric for link adaptation in LTE up‐link systems
Authors: Zhang Shuang , Ren Guangliang , Bai Jialing , Xu Zijie
Published: February 2018

Channel quality metric is an important parameter for the adaptive Long Term Evolution (LTE) uplink, and has a great effect on the performance of the uplink. By modelling the data transmission in the LTE uplink as the complex modulated data pass through the additive Gaussian channel in the transform domain, the authors proposed a new metric, the ratio of the received equivalent average bit power to the average bit error power based on the idea of the modulation error ratio. The adaptive scheme with the proposed metric in the LTE uplink is also given. Simulation results demonstrate that the authors' proposed metric has a better control of the block error rate and can improve % in the throughput compared with the best metric among the conventional channel quality metrics.
EM‐based poor slot update method for MIMO IDD receiver in fast time‐varying channels
Authors: Kim Minsung , Cho Jehoon , Oh Taewon
Published: February 2018

In this study, the authors propose an expectation‐maximisation (EM)‐based poor slot update method for multiple‐input multiple‐output (MIMO) iterative detection and decoding (IDD) receivers to increase their channel tracking capability in fast time‐varying channels. The poor slots that trigger error propagation in a frame are selected, the channel state information is updated, and the updated recursive least squares channel tracking algorithm is executed. The accurate channel tracking capability of this new channel updating technique contributes to a 3 dB improvement in the bit error rate performance of an IDD receiver in a fast mobile environment (). The authors also demonstrate that an % complexity reduction can be achieved under various conditions.
Statistical approach using phase variance for analysing correlated multipath fading environment
Authors: Dhaka Arvind , Bhaskar Vidhyacharan , Nandal Amita , Marina Ninoslav
Published: February 2018

In this study, the authors present an infinite‐series‐based approach for the performance analysis of n‐diversity receivers operating over Rayleigh correlated fading channels in the presence of correlated phase difference. The performance analysis is based on error probability and signal‐to‐noise ratio (SNR) criteria. The authors propose a model to investigate the impact of phase difference between n‐correlated Rayleigh fading channels. We have derived the closed form expression for phase distribution in a Rayleigh fading environment with the help of some statistical properties. The authors have also derived the joint density function of phase difference and its associated correlated envelopes. With the help of probability distribution function, the authors have observed two cases of equally spaced and loosely spaced antennas and showed that imperfect phase estimation lowers the SNR. The authors also present statistical analysis and the effectiveness of the proposed approximation to predict the variance of the phase difference. The authors have performed Monte Carlo simulation for a subcarrier‐based spectrum to analyse error probability with respect to phase and correlation.
Robust non‐overshooting tracking using continuous control for linear multivariable systems
Authors: Xavier Nithin , Bandyopadhyay Bijnan , Schmid Robert
Published: February 2018

A robust continuous control for tracking a step reference signal without any overshoot and arbitrarily small rise time is proposed for a linear multivariable system. Integral sliding mode technique with the super‐twisting sliding mode is used to make the control robust against the matched disturbances with bounded derivatives. Moore's eigenstructure assignment is used to compute nominal control part of the integral sliding mode technique which makes the system output to track the step reference with arbitrarily small rise time and without any overshoot under some mild assumptions. The efficacy of the proposed control is validated using simulation results on benchmark quadruple tank model.
Robust control of an active suspension system with actuator time delay by predictor feedback
Authors: Karim Afshar Keyvan , Javadi Ali , Jahed‐Motlagh Mohammad Reza
Published: February 2018

In this study, a delay‐dependent memory state‐feedback controller for linear systems with input time‐delay in the presence of external disturbance has been investigated. At first, a new formula is introduced to obtain the prediction vector from the system dynamics and then by using this formula, the effect of input time‐delay on the original delayed system is reduced. To guarantee the prescribed disturbance attenuation level of the closed‐loop system, Lyapunov theory and linear matrix inequality (LMI) approaches are used. In the case of feasibility, sufficient LMI conditions provide the stabilising gain of the predictor‐based controller. To illustrate the effectiveness of the proposed method, it is applied to a quarter‐car model of an active suspension system considering the actuator time‐delay.
Estimator design of switched linear systems under unknown persistent excitation
Authors: Li Can , Lian Jie
Published: February 2018

In this study, the robust estimation problem is investigated for discrete‐time switched linear systems with unknown persistent excitation. The robust current estimator is proposed to estimate the real state of the switched systems without the stability restriction. The estimator input is constructed based on the current and previous information of a switching signal and output measurement. Owing to the reference system and its estimator, the exponential stability of the estimation error systems is presented under the average dwell time switching and arbitrary switching. The upper bound or the property of attenuation is unnecessary for the unknown input considered here. In addition, neither the conventional decoupling principle nor non‐singular transformation is employed. At last, the effectiveness of established results is illustrated by a numerical example and a DC–DC boost converter.
Multi‐bit quantisation for similarity‐preserving hashing
Authors: Su Liang Liang , Tang Jun , Liang Dong , Zhu Ming
Published: February 2018

As a promising alternative to traditional search techniques, hashing‐based approximate nearest neighbour search provides an applicable solution for big data. Most existing efforts are devoted to finding better projections to preserve the neighbouring structure of original data points in Hamming space, but ignore the quantisation procedure which may lead to the breakdown of the neighbouring structure maintained in the projection stage. To address this issue, the authors propose a novel multi‐bit quantisation (MBQ) method using a Matthews correlation coefficient (MCC) term and a regularisation term. The authors' method utilises the neighbouring relationship and the distribution information of original data points instead of the projection dimension usually used in the previous MBQ methods to adaptively learn optimal quantisation thresholds, and allocates multiple bits per projection dimension in terms of the learned thresholds. Experiments on two typical image data sets demonstrate that the proposed method effectively preserves the similarity between data points in the original feature space and outperforms state‐of‐the‐art quantisation methods.
Model reference adaptive control of STATCOM for grid integration of wind energy systems
Authors: Mosaad Mohamed I.
Published: February 2018

This article proposes a model reference adaptive control (MRAC) of static synchronous compensator (STATCOM) for enhancing the integration of driven wind turbine‐based self‐excited induction generator (SEIG) into electrical grids. An MRAC‐based Massachusetts Institute of Technology adaptive mechanism is utilised to control the reactive power flow of grid‐integrated SEIG. The voltage‐source inverter sinusoidal pulse width modulation of the STATCOM is used to overcome the abnormal operating conditions in the wind energy conversion system. This accordingly increases the low‐voltage ride through (LVRT) capability. The abnormal operating conditions are faults occurring at the point of common coupling between the generator and the grid. The proposed MRAC is compared to proportional‐integral (PI) controllers tuned by genetic algorithm (GA). To evaluate the proposed control of STATCOM for enhancing grid‐integrated SEIG, a part of the Egyptian 220 kV network integrated with Zafarana Wind Energy System is used. The results provide evidence of an efficient and robust proposed adaptive control performance rather than static PI controller whose parameters tuned by GA in the voltage, currents, and wind generator speed responses. Moreover, the proposed controller increases the capability of continuous operation of the wind turbines under different abnormal operating conditions and also increases the LVRT capability.
Transcallosal, Transchoroidal Resection of a Recurrent Craniopharyngioma
Authors: Jean Walter
Published: February 2018

Objective To demonstrate the transchoroidal approach for the resection of a recurrent craniopharyngioma.

Design Video case report.

Setting Microsurgical resection.

Participant The patient was a 27-year-old woman with a history of a craniopharyngioma, resected twice during the year prior to presentation to our unit. Both operations were done via the left anterolateral corridor, and afterward, she was blind in the left eye and was treated with Desmopressin (DDAVP) for diabetes insipidus (DI). Serial magnetic resonance imaging (MRI) showed progression of the tumor residual, and she was referred for further surgical intervention.

Main Outcome Measures Pre- and postoperative MRIs measured the degree of resection.

Results For this, her third surgery, a transcallosal, transchoroidal approach, was chosen to offer the widest possible exposure. Given her history, an aggressive total resection was the best strategy. The patient was placed supine with the head neutral. A right frontal craniotomy allowed access to the interhemispheric fissure. By opening the corpus callosum, the left lateral ventricle was entered. The transchoroidal approach started with dissection of the tenia fornicis to open the choroidal fissure. After this, sufficient exposure to the posterior parts of the tumor was gained. Resection proceeded to the bottom of the tumor, exposing the basilar apex and interpeduncular cistern, and continued back anteriorly. In the end, a microscopic total resection was achieved. With a long hospital stay to treat her brittle DI, the patient slowly returned to neurological baseline.

Conclusion The transchoroidal approach is an effective way to remove large tumors in the third ventricle.

The link to the video can be found at: https://youtu.be/2-Aqjaay8dg.
The Utility of Repeat Midtrimester Anatomy Ultrasound for Anomaly Detection
Authors: Wood S. , Owen John , Jenkins Sheri , Harper Lorie
Published: February 2018

Introduction Although guidelines recommend repeat ultrasound in the setting of an incomplete fetal anatomic survey, the clinical utility of this practice has not been established. As such, we aimed to assess the yield of repeat ultrasound for anomaly detection following an incomplete survey.

Materials and Methods This is a retrospective cohort study of all singletons who underwent a midtrimester anatomic ultrasound at University of Alabama at Birmingham (UAB) from 2006 to 2014. Patients with an incomplete ultrasound underwent repeat examinations until completion. The population was divided into cohorts FIRST, SECOND, and THIRD, corresponding to the ultrasound at which the exam was deemed complete. Each detected anomaly was tallied. The number of ultrasounds needed to detect an anomaly was then assessed per group.

Results Of 15,768 ultrasounds performed on 13,740 patients, 11,828 exams were completed on first attempt; 1,796 patients required a second, while 116 patients required a third scan or more. We detected 324 anomalies; 93.8% in FIRST, 5.9% in SECOND, and 0.3% in THIRD. The number of scans needed to detect an anomaly was 39, 189, and 348 for FIRST, SECOND, and THIRD, respectively.

Conclusion Over 90% of anomalies are detected on the initial fetal anatomic survey. The incremental diagnostic yield then decreases, requiring appreciably more repeat scans to detect one anomaly.
Variability in the Clock Face View Description of Femoral Tunnel Placement in ACL Reconstruction Using MRI-Based Bony Models
Authors: Patel Kushal , Hosseini Ali , Li Guoan , Gill Thomas , Bravman Jonathan , Kraeutler Matthew
Published: February 2018

Though controversial, the “clock face view” of the intercondylar notch remains a way some surgeons communicate regarding placement of the femoral tunnel in anterior cruciate ligament reconstruction. The purpose of this study was to quantify the differences in angle measurement between several previous descriptions of the clock face view by using a new reference standard. Three-Tesla magnetic resonance imaging (MRI) was used to scan 10 human knees to create three-dimensional MRI-based bony models which were used for measurements. A standardized clock face view was developed with the knee flexed to 90° using the junction of the cartilage and cortex of the medial and lateral surfaces of medial and lateral femoral condyles as the 3 o'clock and 9 o'clock, respectively, with the 12 o'clock established as the midpoint of the roof of the intercondylar notch. With the knee viewed at 90° of flexion, an “idealized” femoral tunnel position was plotted on the medial wall of the lateral femoral condyle at 30° (corresponding to the 10 o'clock or 2 o'clock position). The clock faces as described by Edwards et al, Heming et al, and Mochizuki et al were each then overlaid on this same model and the difference in measurement calculated. The average angles measured when the previously described clock faces were projected onto the idealized clock face view comparing a mark made at 30° were 47.7°, 7.2°, and 49.8° for the methods described by Edwards et al, Heming et al, and Mochizuki et al, respectively (all p < 0.001). Significant variation exists between angle measurements in simulated femoral tunnel placement based on the varying descriptions of the intercondylar clock face.
Heparin-Induced Thrombocytopenia during Obstetric Hospital Admissions
Authors: Sagaram Deepika , Siddiq Zainab , Eisenberger Andrew , Ananth Cande , Wright Jason , D'Alton Mary , Friedman Alexander
Published: February 2018

Introduction The rate of heparin-induced thrombocytopenia (HIT) on a population basis is unknown. The objective of this study was to characterize the risk for HIT during antepartum, delivery, and postpartum hospitalizations in the United States.

Materials and Methods A large administrative database was used to determine the risk of HIT in hospitalized obstetric patients who received unfractionated heparin (UFH) or low molecular weight heparin (LMWH). Patients were presumed to have HIT if they were exposed to UFH or LMWH, received a diagnosis of HIT, and were administered a medication for the treatment of HIT including bivalirudin, argatroban, fondaparinux, or lepirudin. We queried severe complications of HIT including arterial thrombosis, limb amputation, heart failure, and death.

Results We identified 66,468 antepartum hospitalizations, 66,741 delivery hospitalizations, and 16,325 postpartum readmissions where women received pharmacologic prophylaxis. Of these, 10 antepartum admissions, 1 delivery admission, and 14 postpartum readmissions involved a diagnosis of HIT with treatment of bivalirudin, argatroban, fondaparinux, or lepirudin. There were no deaths and no diagnoses of arterial thrombosis, limb amputation, heart failure, and death.

Conclusion Risk for HIT among hospitalized obstetric patients is low. In this cohort, no cases of death or severe complications were noted in relation to the diagnosis.
Endoscopic Transsphenoidal Salvage Surgery for Symptomatic Residual Cystic Craniopharyngioma after Radiotherapy
Authors: Emanuelli Enzo , Frasson Giuliana , Cazzador Diego , Borsetto Daniele , Denaro Luca
Published: February 2018

Objectives Ideal treatment of craniopharyngiomas is still controversial. Radiotherapy (RT) is considered effective for recurrences or after subtotal tumor removal (STR). About 40 to 50% of patients may experience tumor cyst expansion soon after RT; in these cases, the role of salvage surgery is debated.

Design Operative video.

Setting Tertiary care center.

Participants An 11-year-old boy diagnosed with persistent craniopharyngioma. In 2015, the patient underwent right frontotemporal craniotomy for STR at another center, complicated by panhypopituitarism. Two years later, fractionated 54-Gy RT was performed on growing residual tumor. After 3 months, he was admitted to our hospital due to persistent malaise, vomiting, pulsating headache, and epistaxis. Ophthalmologic evaluation evidenced left homonymous hemianopsia.

Results A contrast-enhanced magnetic resonance imaging (MRI) showed a 27-mm cystic component enlarging from the cranial end of the persistent craniopharyngioma lesion, extending into the third ventricle. Biventricular hydrocephalus and brain midline shift to the right were present. Compared with the early post-RT MRI, the cystic component of the tumor demonstrated growth. The patient underwent external ventricular drainage placement for emergent treatment of hydrocephalus and endoscopic transsphenoidal surgery. After cystic content drainage, the lesion was completely removed with its capsule. A “gasket seal” technique was performed for skull base reconstruction, with autologous fascia lata, septal bone, and mucoperiosteum from inferior turbinate. Histologic examination confirmed the craniopharyngioma diagnosis. Postoperative MRI showed resolution of the hydrocephalus and complete tumor removal.

Conclusion Although shrinkage of cystic components of craniopharyngioma residuals may occur within 5 to 6 months after RT, salvage surgery is indicated in symptomatic patients.

The link to the video can be found at https://youtu.be/4x6Qe76bf60.
A table top experiment to investigate production and properties of a plasma confined by a dipole magnet
Authors: Baitha Anuj Ram , Kumar Ashwani , Bhattacharjee Sudeep
Published: February 2018

We report a table top experiment to investigate production and properties of a plasma confined by a dipole magnet. A water cooled, strong, cylindrical permanent magnet (NdFeB) magnetized along the axial direction and having a surface magnetic field of ∼0.5 T is employed to create a dipole magnetic field. The plasma is created by electron cyclotron resonance heating. Visual observations of the plasma indicate that radiation belts appear due to trapped particles, similar to the earth’s magnetosphere. The electron temperature lies in the range 2–13 eV and is hotter near the magnets and in a downstream region. It is found that the plasma (ion) density reaches a value close to 2 × 1011 cm−3 and peaks at a radial distance about 3 cm from the magnet. The plasma beta β (β = plasma pressure/magnetic pressure) increases radially outward, and the maximum β for the present experimental system is ∼2%. It is also found that the singly charged ions are dominant in the discharge.
Increased interference fringe visibility from the post-fabrication heat treatment of a perfect crystal silicon neutron interferometer
Authors: Heacock B. , Arif M. , Cory D. G. , Gnaeupel-Herold T. , Haun R. , Huber M. G. , Jamer M. E. , Nsofini J. , Pushin D. A. , Sarenac D. , Taminiau I. , Young A. R.
Published: February 2018

We find that annealing a previously chemically etched interferometer at 800 °C dramatically increased the interference fringe visibility from 23% to 90%. The Bragg plane misalignments were also measured before and after annealing using neutron rocking curves, showing that Bragg plane alignment was improved across the interferometer after annealing. This suggests that current interferometers with low fringe visibility may be salvageable and that annealing may become an important step in the fabrication process of future neutron interferometers, leading to less need for chemical etching and larger more exotic neutron interferometers.
Optical properties of electrically connected plasmonic nanoantenna dimer arrays
Authors: Zimmerman Darin T. , Borst Benjamin D. , Carrick Cassandra J. , Lent Joseph M. , Wambold Raymond A. , Weisel Gary J. , Willis Brian G.
Published: February 2018

We fabricate electrically connected gold nanoantenna arrays of homodimers and heterodimers on silica substrates and present a systematic study of their optical properties. Electrically connected arrays of plasmonic nanoantennas make possible the realization of novel photonic devices, including optical sensors and rectifiers. Although the plasmonic response of unconnected arrays has been studied extensively, the present study shows that the inclusion of nanowire connections modifies the device response significantly. After presenting experimental measurements of optical extinction for unconnected dimer arrays, we compare these to measurements of dimers that are interconnected by gold nanowire “busbars.” The connected devices show the familiar dipole response associated with the unconnected dimers but also show a second localized surface plasmon resonance (LSPR) that we refer to as the “coupled-busbar mode.” Our experimental study also demonstrates that the placement of the nanowire along the antenna modifies the LSPR. Using finite-difference time-domain simulations, we confirm the experimental results and investigate the variation of dimer gap and spacing. Changing the dimer gap in connected devices has a significantly smaller effect on the dipole response than it does in unconnected devices. On the other hand, both LSPR modes respond strongly to changing the spacing between devices in the direction along the interconnecting wires. We also give results for the variation of E-field strength in the dimer gap, which will be important for any working sensor or rectenna device.
Study of magnetization and magnetoelectricity in CoFe2O4/BiFeO3 core-shell composites
Authors: Kuila S. , Tiwary Sweta , Sahoo M. R. , Barik A. , Babu P. D. , Siruguri V. , Birajdar B. , Vishwakarma P. N.
Published: February 2018

CoFe2O4 (core)/BiFeO3 (shell) nanoparticles are prepared by varying the relative molar concentration of core and shell materials (40%CoFe2O4-60%BiFeO3, 50%CoFe2O4-50%BiFeO3, and 60%CoFe2O4-40%BiFeO3). The core-shell nature is confirmed from transmission electron microscopy on these samples. A plot of ΔM (=MFC-MZFC) vs temperature suggests the presence of two types of spin dynamics: (a) particle size dependent spin blocking and (b) spin-disorder. These two spin dynamic processes are found to contribute independently to the generation of magnetoelectric voltage. Very clear first order and second order magnetoelectric voltages are recorded. The resemblance of the first order magnetoelectric coefficient vs temperature plot to that of building up of order parameters in the mean field theory suggests that spin disorder can act like one of the essential ingredients in building the magnetoelectric coupling. The best result is obtained for the 50-50 composition sample, which may be due to better coupling of magnetostrictive CoFe2O4, and piezoelectric BiFeO3, because of the optimum thickness of shell and core.
Reduction of asymmetric wall force in ITER disruptions with fast current quench
Authors: Strauss H.
Published: February 2018

One of the problems caused by disruptions in tokamaks is the asymmetric electromechanical force produced in conducting structures surrounding the plasma. The asymmetric wall force in ITER asymmetric vertical displacement event (AVDE) disruptions is calculated in nonlinear 3D MHD simulations. It is found that the wall force can vary by almost an order of magnitude, depending on the ratio of the current quench time to the resistive wall magnetic penetration time. In ITER, this ratio is relatively low, resulting in a low asymmetric wall force. In JET, this ratio is relatively high, resulting in a high asymmetric wall force. Previous extrapolations based on JET measurements have greatly overestimated the ITER wall force. It is shown that there are two limiting regimes of AVDEs, and it is explained why the asymmetric wall force is different in the two limits.
Band edge states, intrinsic defects, and dopants in monolayer HfS2 and SnS2
Authors: Lu Haichang , Guo Yuzheng , Robertson John
Published: February 2018

Although monolayer HfS2 and SnS2 do not have a direct bandgap like MoS2, they have much higher carrier mobilities. Their band offsets are favorable for use with WSe2 in tunnel field effect transistors. Here, we study the effective masses, intrinsic defects, and substitutional dopants of these dichalcogenides. We find that HfS2 has surprisingly small effective masses for a compound that might appear partly ionic. The S vacancy in HfS2 is found to be a shallow donor while that in SnS2 is a deep donor. Substitutional dopants at the S site are found to be shallow. This contrasts with MoS2 where donors and acceptors are not always shallow or with black phosphorus where dopants can reconstruct into deep non-doping configurations. It is pointed out that HfS2 is more favorable than MoS2 for semiconductor processing because it has the more convenient CVD precursors developed for growing HfO2.
Characterization of atomic spin polarization lifetime of cesium vapor cells with neon buffer gas
Authors: Lou Janet W. , Cranch Geoffrey A.
Published: February 2018

The dephasing time of spin-polarized atoms in an atomic vapor cell plays an important role in determining the stability of vapor-cell clocks as well as the sensitivity of optically-pumped magnetometers. The presence of a buffer gas can extend the lifetime of these atoms. Many vapor cell systems operate at a fixed (often elevated) temperature. For ambient temperature operation with no temperature control, it is necessary to characterize the temperature dependence as well. We present a spin-polarization lifetime study of Cesium vapor cells with different buffer gas pressures, and find good agreement with expectations based on the combined effects of wall collisions, spin exchange, and spin destruction. For our (7.5 mm diameter) vapor cells, the lifetime can be increased by two orders of magnitude by introducing Ne buffer gas up to 100 Torr. Additionally, the dependence of the lifetime on temperature is measured (25 - 47 oC) and simulated for the first time to our knowledge with reasonable agreement.
Nano-indentation used to study pyramidal slip in GaN single crystals
Authors: Krimsky E. , Jones K. A. , Tompkins R. P. , Rotella P. , Ligda J. , Schuster B. E.
Published: February 2018

The nucleation and structure of dislocations created by the nano-indentation of GaN samples with dislocation densities ≈103, 106 or 109 ⊥/cm2 were studied in the interest of learning how dislocations can be created to relieve the mismatch strain in ternary nitride films grown on (0001) oriented binary nitride substrates. Using transmission electron microscopy and stress analyses to assist in interpreting the nano-indentation data, we determined that the pop-ins in the indenter load vs. penetration depth curves are created by an avalanche process at stresses well above the typical yield stress. The process begins by the homogeneous formation of a basal plane screw dislocation that triggers the formation of pyramidal and other basal plane dislocations that relieve the excess stored elastic energy. It appears that pyramidal slip can occur on either the {1122} or {0111} planes, as there is little resistance to the cross slip of screw dislocations.
Laplace transformed MP2 for three dimensional periodic materials using stochastic orbitals in the plane wave basis and correlated sampling
Authors: Schäfer Tobias , Ramberger Benjamin , Kresse Georg
Published: February 2018

We present an implementation and analysis of a stochastic high performance algorithm to calculate the correlation energy of three-dimensional periodic systems in second-order Møller-Plesset perturbation theory (MP2). In particular we measure the scaling behavior of the sample variance and probe whether this stochastic approach is competitive if accuracies well below 1 meV per valence orbital are required, as it is necessary for calculations of adsorption, binding, or surface energies. The algorithm is based on the Laplace transformed MP2 (LTMP2) formulation in the plane wave basis. The time-dependent Hartree-Fock orbitals, appearing in the LTMP2 formulation, are stochastically rotated in the occupied and unoccupied Hilbert space. This avoids a full summation over all combinations of occupied and unoccupied orbitals, as inspired by the work of Neuhauser, Rabani, and Baer [J. Chem. Theory Comput. 9, 24 (2013)]. Additionally, correlated sampling is introduced, accelerating the statistical convergence significantly.
Effects of mechanical strain on optical properties of ZnO nanowire
Authors: Vazinishayan Ali , Lambada Dasaradha Rao , Yang Shuming , Zhang Guofeng , Cheng Biyao , Woldu Yonas Tesfaye , Shafique Shareen , Wang Yiming , Anastase Ndahimana
Published: February 2018

The main objective of this study is to investigate the influences of mechanical strain on optical properties of ZnO nanowire (NW) before and after embedding ZnS nanowire into the ZnO nanowire, respectively. For this work, commercial finite element modeling (FEM) software package ABAQUS and three-dimensional (3D) finite-difference time-domain (FDTD) methods were utilized to analyze the nonlinear mechanical behavior and optical properties of the sample, respectively. Likewise, in this structure a single focused Gaussian beam with wavelength of 633 nm was used as source. The dimensions of ZnO nanowire were defined to be 12280 nm in length and 103.2 nm in diameter with hexagonal cross-section. In order to investigate mechanical properties, three-point bending technique was adopted so that both ends of the model were clamped with mid-span under loading condition and then the physical deformation model was imported into FDTD solutions to study optical properties of ZnO nanowire under mechanical strain. Moreover, it was found that increase in the strain due to the external load induced changes in reflectance, transmittance and absorptance, respectively.
Enhanced graphene nonlinear response through geometrical plasmon focusing
Authors: Saavedra J. R. M. , García de Abajo F. Javier
Published: February 2018

We propose a simple approach to couple light into graphene plasmons and focus these excitations at focal spots of a size determined by the plasmon wavelength, thus producing high optical field enhancement that boosts the nonlinear response of the material. More precisely, we consider a graphene structure in which incident light is coupled to its plasmons at the carbon edges and subsequently focused on a spot of size comparable to the plasmon wavelength. We observe large confinement of graphene plasmons, materializing in small, intense focal spots, in which the extraordinary nonlinear response of this material leads to relatively intense harmonic generation. This result shows the potential of plasmon focusing in suitably edged graphene structures to produce large field confinement and nonlinear response without involving elaborated nanostructuring.
Thymic involution and rising disease incidence with age
Authors: Palmer Sam , Albergante Luca , Blackburn Clare C. , Newman T. J.
Published: February 2018

Significance

Understanding the risk factors of carcinogenesis is a major goal of biomedical research. Historically, the focus has been on the role of somatic mutations, and the reason for cancer typically occurring late in life is predominantly attributed to a gradual accumulation of such mutations. We challenge that view and propose that the decline of the immune system is the primary reason why cancer is an age-related disease. The immunological model featured here captures risk profiles for many cancer types and infectious diseases, suggesting that therapies reversing T cell exhaustion or restoring T cell production will be promising avenues of treatment.
Capping protein regulates actin dynamics during cytokinetic midbody maturation
Authors: Terry Stephen J. , Donà Federico , Osenberg Paul , Carlton Jeremy G. , Eggert Ulrike S.
Published: February 2018

Significance

Actin dynamics drive many steps of cell division. Here, we show that the actin capping protein (CP) is unexpectedly involved in midbody maturation, a poorly understood phase of the cell cycle where cells remodel their intercellular bridges to prepare for separation. The loss of CP results in excessive filamentous actin throughout the cell cycle, but only postfurrowing cytokinesis is inhibited. We propose that optimal actin filament function is achieved by a balance between CP-dependent filament capping and formin-driven polymerization. This raises the intriguing possibility that cells utilize specific types of actin filament networks to progress through division. This finding has profound implications on understanding actin-dependent processes such as cell division, migration, adhesion, and morphogenesis.
Finite-size effects in the short-time height distribution of the Kardar–Parisi–Zhang equation
Authors: Smith Naftali R , Meerson Baruch , Sasorov Pavel
Published: February 2018

We use the optimal fluctuation method to evaluate the short-time probability distribution

P

(
H
,
L
,
t
)

of height at a single point,

H
=
h

(
x
=
0
,
t
)

, of the evolving Kardar–Parisi–Zhang (KPZ) interface

h

(
x
,
t
)

on a ring of length 2L. The process starts from a flat interface. At short times typical (small) height fluctuations are unaffected by the KPZ nonlinearity and belong to the Edwards–Wilkinson universality class. The nonlinearity, however, strongly affects the (asymmetric) tails of

P

(
H
)

. At large

L

/

t

the faster-decaying tail has a double structure: it is L-independent,

−
ln

P

∼

|
H
|

5

/

2

/

t

1

/

2

, at intermediately large

|
H
|

, and L-dependent,

−
ln

P

∼

|
H
|

2

L

/

t

, at very large

|
H
|

. The transition between these two regimes is sharp and, in the large

L

/

t

limit, behaves as a fractional-order phase transition. The transition point

H
=

H

c

+

depends on

L

/

t

. At small

L

/

t

, the double structure of the faster tail disappears, and only the very large-H tail,

−
ln

P

∼

|
H
|

2

L

/

t

, is observed. The slower-decaying tail does not show any L-dependence at large

L

/

t

, where it coincides with the slower tail of the GOE Tracy–Widom distribution. At small

L

/

t

this tail also has a double structure. The transition between the two regimes occurs at a value of height

H
=

H

c

−

which depends on

L

/

t

. At

L

/

t

→
0

the transition behaves as a mean-field-like second-order phase transition. At

|
H
|
<
|

H
c

−

|

the slower tail behaves as

−
ln

P

∼

|
H
|

2

L

/

t

, whereas at

|
H
|
>
|

H
c

−

|

it coincides with the slower tail of the GOE Tracy–Widom distribution.
KMgene: a unified R package for gene-based association analysis for complex traits
Authors: Yan Qi , Fang Zhou , Chen Wei
Published: February 2018

In this report, we introduce an R package KMgene for performing gene-based association tests for familial, multivariate or longitudinal traits using kernel machine (KM) regression under a generalized linear mixed model framework. Extensive simulations were performed to evaluate the validity of the approaches implemented in KMgene.

Availability and implementation

http://cran.r-project.org/web/packages/KMgene.

Supplementary information

Supplementary data are available at Bioinformatics online.
HIITE: HIV-1 incidence and infection time estimator
Authors: Park Sung Yong , Love Tanzy M T , Kapoor Shivankur , Lee Ha Youn
Published: February 2018

Motivation

Around 2.1 million new HIV-1 infections were reported in 2015, alerting that the HIV-1 epidemic remains a significant global health challenge. Precise incidence assessment strengthens epidemic monitoring efforts and guides strategy optimization for prevention programs. Estimating the onset time of HIV-1 infection can facilitate optimal clinical management and identify key populations largely responsible for epidemic spread and thereby infer HIV-1 transmission chains. Our goal is to develop a genomic assay estimating the incidence and infection time in a single cross-sectional survey setting.

Results

We created a web-based platform, HIV-1 incidence and infection time estimator (HIITE), which processes envelope gene sequences using hierarchical clustering algorithms and informs the stage of infection, along with time since infection for incident cases. HIITE’s performance was evaluated using 585 incident and 305 chronic specimens’ envelope gene sequences collected from global cohorts including HIV-1 vaccine trial participants. HIITE precisely identified chronically infected individuals as being chronic with an error less than 1% and correctly classified 94% of recently infected individuals as being incident. Using a mixed-effect model, an incident specimen’s time since infection was estimated from its single lineage diversity, showing 14% prediction error for time since infection. HIITE is the first algorithm to inform two key metrics from a single time point sequence sample. HIITE has the capacity for assessing not only population-level epidemic spread but also individual-level transmission events from a single survey, advancing HIV prevention and intervention programs.

Availability and implementation

Web-based HIITE and source code of HIITE are available at http://www.hayounlee.org/software.html.

Supplementary information

Supplementary data are available at Bioinformatics online.
Incidence of Healthcare-Associated Influenza-Like Illness After a Primary Care Encounter Among Young Children
Authors: Feemster Kristen , Localio Russell , Grundmeier Robert , Metlay Joshua P , Coffin Susan E
Published: February 2018

Background

Despite potential respiratory virus transmission in pediatric clinics, little is known about the risk of healthcare-associated viral infections attributable to outpatient encounters. We evaluated whether exposure to a pediatric clinic visit was associated with subsequent influenza-like illness (ILI).

Methods

Using electronic health record data, we conducted a retrospective cohort study of all children aged <6 years who presented to a provider in a 29-clinic pediatric primary care network for a non–ILI-related encounter over 2 respiratory virus seasons (September 1, 2012, to April 30, 2014). We defined a risk period for potential healthcare-associated (HA) ILI of 1 to 8 days after a non-ILI clinic visit and identified all cases of ILI to compare the incidences of ILI visits 1 to 8 days after a non-ILI encounter and those of visits >8 days after a non-ILI encounter.

Results

Among 149987 children <6 years of age (mean age, 2.5 years) with ≥1 non-ILI visit during the study period, 531928 total encounters and 13951 (2.9%) ILI encounters were identified; 1941 (13.9%) occurred within the HA-ILI risk window. The incidence rate ratios (IRRs) for ILI 1 to 8 days after compared with ILI >8 days after a non-ILI visit during season 1 were 1.36 (95% confidence interval, 1.22–1.52) among children ≥2 years of age and 1.01 (95% confidence interval, 0.93–1.09) among children <2 years of age. Estimates remained consistent during season 2 and with a risk window of 3, 4, or 9 days.

Conclusions

Pediatric clinic visits during a respiratory virus season were significantly associated with an increased incidence of subsequent ILI among children aged 2 to 6 years but not among those aged <2 years. These findings support the hypothesis that respiratory virus transmission in a pediatric clinic can result in HA ILI in young children.
Incidence, Etiology, and Outcomes of Community-Acquired Pneumonia: A Population-Based Study
Authors: Bjarnason Agnar , Westin Johan , Lindh Magnus , Andersson Lars-Magnus , Kristinsson Karl G , Löve Arthur , Baldursson Olafur , Gottfredsson Magnus
Published: February 2018

Background

The microbial etiology of community-acquired pneumonia (CAP) is often unclear in clinical practice, and previous studies have produced variable results. Population-based studies examining etiology and incidence are lacking. This study examined the incidence and etiology of CAP requiring hospitalization in a population-based cohort as well as risk factors and outcomes for specific etiologies.

Methods

Consecutive admissions due to CAP in Reykjavik, Iceland were studied. Etiologic testing was performed with cultures, urine-antigen detection, and polymerase chain reaction analysis of airway samples. Outcomes were length of stay, intensive care unit admission, assisted ventilation, and mortality.

Results

The inclusion rate was 95%. The incidence of CAP requiring hospitalization was 20.6 cases per 10000 adults/year. A potential pathogen was detected in 52% (164 of 310) of admissions and in 74% (43 of 58) with complete sample sets. Streptococcuspneumoniae was the most common pathogen (61 of 310, 20%; incidence: 4.1/10000). Viruses were identified in 15% (47 of 310; incidence: 3.1/10000), Mycoplasmapneumoniae were identified in 12% (36 of 310; incidence: 2.4/10000), and multiple pathogens were identified in 10% (30 of 310; incidence: 2.0/10000). Recent antimicrobial therapy was associated with increased detection of M pneumoniae (P < .001), whereas a lack of recent antimicrobial therapy was associated with increased detection of S pneumoniae (P = .02). Symptoms and outcomes were similar irrespective of microbial etiology.

Conclusions

Pneumococci, M pneumoniae, and viruses are the most common pathogens associated with CAP requiring hospital admission, and they all have a similar incidence that increases with age. Symptoms do not correlate with specific agents, and outcomes are similar irrespective of pathogens identified.
Customized Pessary Fabrication Using Three-Dimensional Printing Technology
Authors: Barsky Michael , Kelley Robert , Bhora Faiz Y. , Hardart Anne
Published: February 2018

BACKGROUND:

Pessaries are a treatment option for pelvic organ prolapse, stress urinary incontinence (SUI), and cervical incompetence. An effective pessary is comfortable, corrects the presenting problem, does not cause adverse effects, and is easy to remove. Discomfort and poor fit limit the usefulness of pessaries for many women. Each patient presents with unique anatomy and thus the effectiveness of commercially available pessaries may be limited by lack of customization.

METHOD:

A patient presenting with SUI and failed commercial pessary fittings desired nonsurgical treatment. Using a mold fabricated with a three-dimensional printer and polylactic acid filament, a medical-grade silicone pessary was custom-made for the patient.

EXPERIENCE:

The silicone pessary was placed vaginally in the patient for a period of 48 hours. The patient did not report any discomfort or bladder leakage. In addition, the pessary did not dislodge with coughing, sneezing, or straining. After removal, a speculum examination showed normal epithelium.

CONCLUSION:

We report the successful insertion of a customized three-dimensional–printed pessary in a patient with SUI. Three-dimensional–printed pessaries are feasible and their utility may extend to the patient with anatomy incompatible with commercially available pessaries.