bluuebunny/crossref_metadata_2025 huggingface dataset:
Unsupervised change detection of flood affected areas in SAR images using Rayleigh‐based Bayesian thresholding
Authors: Sumaiya Mohammed Naina , Shantha Selva Kumari Ramapackiam
Published: February 2018

In the Bayesian context, the rationale for using a particular probability density function (pdf) for a synthetic aperture radar (SAR) image improves the performance of unsupervised change detection (CD). So, this work is concentrated on promoting the consequence of selecting an empirical pdf and its parameter estimation technique. Rayleigh pdf is used to model approximation and detail sub‐bands of a dual tree complex wavelet transform (DTCWT) of the log ratio difference image. The chosen pdf has a potential impact on impulsive SAR images. The scale parameter of Rayleigh pdf is estimated using first‐order moments by exploiting Mellin transform. This iteration‐free parameter estimation technique, made the method faster. In each sub‐band at each level of DTCWT decomposition, the binary threshold is estimated to represent the change signal at different scales. The performance in the final change map is improved by combining intra‐scale along with inter‐scale sub‐band coefficients. The proposed method is tested on three flooding SAR image data sets acquired from European Space Agency environmental satellite, European remote‐sensing satellite (ERS)‐2 and ERS‐1 SAR instruments. The experimental results show that the proposed method achieves good CD performance in terms of false alarm rate and overall detection accuracy in less computing time.
Rotor position estimation of wound‐rotor synchronous starter/generator
Authors: Zhu Yujie , Liu Weiguo , Meng Tao , Peng Jichang , Jiao Ningfei
Published: February 2018

This study proposes a novel rotor position estimation method for wound‐rotor synchronous starter/generator (WSSG). At starting stage, WSSG needs a resolver to obtain main generator (MG)'s rotor position. However, the use of resolver increases starting system's complexity, volume, weight and cost. In order to solve this problem, a new kind of MG's rotor position estimation method is proposed, which considers the structure of WSSG as a resolver. This method injects a rotating voltage into MG's stator, detects main exciter's stator currents and subsequently processes the current signals to estimate MG's rotor position. Experiment results show that this method has high estimation accuracy, which are in good agreement with the theoretical analyses and simulation results. Compared to the traditional saliency tracking rotor position estimation method, this method does not rely on WSSG's parameters (including MG's saliency), and the signal processing procedures are more simple.
Magnetic field topology of the cool, active, short-period binary system σ2 Coronae Borealis
Authors: Rosén L. , Kochukhov O. , Alecian E. , Neiner C. , Morin J. , Wade G. A. ,   the BinaMIcS collaboration
Published: February 2018

Aims. The goal of this work is to study the cool, active binary star σ2 CrB, focussing on its magnetic field. The two F9–G0 components of this system are tidally locked and in a close orbit, increasing the chance of interaction between their magnetospheres.

Methods. We used Stokes IV data from the twin spectropolarimeters Narval at the TBL and ESPaDOnS at the CFHT. The least-squares deconvolution multi-line technique was used to increase the signal-to-noise ratio of the data. We then applied a new binary Zeeman–Doppler imaging code to reconstruct simultaneously the magnetic topology and brightness distribution of both components of σ2 CrB. This analysis was carried out for two observational epochs in 2014 and 2017.

Results. A previously unconfirmed magnetic field of the primary star has been securely detected. At the same time, the polarisation signatures of the secondary appear to have a systematically larger amplitude than that of the primary. This corresponds to a stronger magnetic field, for which the magnetic energy of the secondary exceeds that of the primary by a factor of 3.3–5.7. While the magnetic energy is similar for the secondary star in the two epochs, the magnetic energy is about twice as high in 2017 for the primary. The magnetic field topology of the two stars in the earlier epoch (2014) is very different. The fractions of energy in the dipole and quadrupole components of the secondary are similar and thereafter decrease with increasing harmonic angular degree ℓ. At the same time, for the primary the fraction of energy in the dipole component is low and the maximum energy contribution comes from ℓ = 4. However, in the 2017 epoch both stars have similar field topologies and a systematically decreasing energy with increasing ℓ. In the earlier epoch, the magnetic field at the visible pole appears to be of opposite polarity for the primary and secondary, suggesting linked magnetospheres. The apparent rotational periods of both σ2 CrB components are longer than the orbital period, which we interpret as an evidence of a solar-like differential rotation.

Conclusions. Despite their nearly identical fundamental parameters, the components of σ2 CrB system exhibit different magnetic field properties. This indicates that the magnetic dynamo process is a very sensitive function of stellar parameters.
Effets de la pâture sur la dynamique de la végétation herbacée au Sahel (Gourma, Mali) : une approche par modélisation
Authors: Diawara Mamadou Oumar , Hiernaux Pierre , Mougin Eric , Grippa Manuela , Delon Claire , Diakité Hawa Salif
Published: February 2018

Au Sahel, la végétation se compose d’une strate herbacée principalement composée de plantes annuelles et d’une strate ligneuse peu dense dominée par des épineux. Dans cette région, l’essentiel de la production fourragère a lieu entre juillet et septembre. Le disponible fourrager constitué au cours de cette courte période décroît durant les neuf mois de la saison sèche sous l’effet de plusieurs facteurs, dont la pâture des ruminants domestiques. Les effets de la pâture sur la dynamique saisonnière de la phytomasse herbacée ont fait l’objet de peu d’études au Sahel. La dynamique de saison sèche de la phytomasse herbacée sous l’effet de la pâture est simulée à l’aide du module « Patsec » du modèle STEP. Une étude de sensibilité du module Patsec à la composition spécifique, l’intensité et la saisonnalité de la charge compare les sorties du module aux observations faites en 2010–2011 sur trois sites pastoraux proches de Hombori à l’Est du Sahel malien. Les résultats montrent que le prélèvement fourrager par le bétail ne contribue que de façon secondaire à la « dégradation » saisonnière de la phytomasse herbacée. Par contre, les effets de la pâture sur le transfert des pailles dressées à la litière et l’enfouissement dans le sol de cette dernière sont nets. L’étude montre également qu’à charge égale exprimée en poids vif, la pâture par les bovins contribue moins au transfert paille-litière et à l’enfouissement de la litière que la pâture de petits ruminants, malgré l’importance du fourrage ligneux dans la ration des chèvres. Le modèle testé reproduit de façon satisfaisante la dynamique saisonnière de la phytomasse herbacée et peut servir d’outil de prévention des crises pastorales liées aux pénuries de fourrage en région sahélienne à travers un suivi de la charge animale et du disponible fourrager de saison sèche.
The occurrence of antibiotic resistance genes in tap water – a review
Authors: Siedlecka Agata
Published: February 2018

The study presents a review of the occurrence of genetic determinants of antibiotic resistance in tap water. The aim of this study was also to compare the applied methods for antibiotic resistance genes (ARGs) investigations in tap water. As the concentration of ARGs in treated, drinking water is expected to be very low and may cause problems in a standard isolation procedure, the special emphasis is placed on the applied procedures of DNA extraction and their efficiency. The study presents the first attempts to obtain DNA directly from tap water. Further efforts must be put to determine the final amount of obtained DNA and the presence of chosen ARGs among the molecules.
A comparative analysis of selected wastewater pretreatment processes in food industry
Authors: Jaszczyszyn Katarzyna , Góra Wojciech , Dymaczewski Zbysław , Borowiak Robert
Published: February 2018

The article presents a comparative analysis of the classical coagulation with the iron sulphate and adsorption on bentonite for the pretreatment of wastewater in the food industry. As a result of the studies, chemical oxygen demand (COD) and total nitrogen (TN) reduction were found to be comparable in both technologies, and a 29% higher total phosphorus removal efficiency by the coagulation was observed. After the coagulation and adsorption processes, a significant difference between mineral and organic fraction in the sludge was found (49% and 51% for bentonite and 28% and 72% for iron sulphate, respectively).
The virtual enhancements − solar proton event radiation (VESPER) model
Authors: Aminalragia-Giamini Sigiava , Sandberg Ingmar , Papadimitriou Constantinos , Daglis Ioannis A. , Jiggens Piers
Published: February 2018

A new probabilistic model introducing a novel paradigm for the modelling of the solar proton environment at 1 AU is presented. The virtual enhancements − solar proton event radiation model (VESPER) uses the European space agency's solar energetic particle environment modelling (SEPEM) Reference Dataset and produces virtual time-series of proton differential fluxes. In this regard it fundamentally diverges from the approach of existing SPE models that are based on probabilistic descriptions of SPE macroscopic characteristics such as peak flux and cumulative fluence. It is shown that VESPER reproduces well the dataset characteristics it uses, and further comparisons with existing models are made with respect to their results. The production of time-series as the main output of the model opens a straightforward way for the calculation of solar proton radiation effects in terms of time-series and the pairing with effects caused by trapped radiation and galactic cosmic rays.
Glycosylated α-Azido Amino Acids: Versatile Intermediates in the Synthesis of Neoglycoconjugates
Authors: Velasco-Torrijos Trinidad , O’Flaherty Róisín
Published: February 2018

A series of glycosylated α-azido amino acids was synthesized as precursors for neoglycoconjugates, a class of important biomolecules for drug discovery, and sensor development. The synthetically challenging 1,2-cis α-galactosylated species described herein were designed as building blocks in the synthesis of analogues of α-galactosyl ceramide, a potent immunomodulator. A benzyl-protected 1,2,3-triazolyl α-galactosyl-l-serine derivative was prepared using copper azide alkyne cycloaddition to showcase the potential of glycosylated α-azido amino acids in neoglycoconjugate design.
Divergent Oxidative Couplings between Indoles and 2,3-Dihydroxybenzoic Acid Derivatives for the Biomimetic Synthesis of Voacalgine A and Bipleiophylline
Authors: Poupon Erwan , Evanno Laurent , Vincent Guillaume , Denizot Natacha , Lachkar David , Kouklovsky Cyrille
Published: February 2018

The present feature article details our endeavors towards the synthesis of the highly intricate bisindole alkaloid bipleiophylline and its biosynthetic precursor voacalgine A: from the development of a divergent oxidative coupling between indole and dihydroxybenzoic acids, to the exploration of the chemical space from natural products and culminating in the biomimetic assembly of voacalgine A and bipleiophylline.
Percutaneous Image-Guided Treatment of Benign Musculoskeletal Tumors in Children
Authors: Gill Anne , Hawkins C. , O'Dell Matthew
Published: February 2018

Percutaneous ablation of benign musculoskeletal tumors in children has become an area of significant clinical growth over the last decade. With growing research interest, the technologies available and techniques used are becoming increasingly safe and effective. We review some of the more common ablation technologies and their utility in several common benign bone and soft tissue tumors that occur in children and young adults.
Ankle and Foot Injuries in the Young Athlete
Authors: Jaimes Camilo , Khwaja Asef , Chauvin Nancy
Published: February 2018

Injuries to the ankle and foot are common in the young athlete, especially with increasing participation and high levels of competitiveness in youth sports programs. Knowledge of the normal development of the foot and ankle is crucial to understand age-specific injury patterns because acute or chronic/repetitive stress to the developing skeleton results in injuries that differ from those seen in adults. Congenital abnormalities may also predispose children to increased risk of injury and pain. Radiologists must be aware of these distinctions to diagnose and classify injuries correctly for optimum treatment. We describe common and unique foot and ankle injuries in the young athlete. Throughout the article we focus not only on imaging findings but also on the mechanism of injury.
Managing the Lower Eyelid Complex in the Thick-Skinned Patient
Authors: Perkins Stephen , Floyd Elizabeth
Published: February 2018

Thick skin presents a unique set of challenges within the realm of facial plastic surgery, and addressing the lower lid complex is no exception. There are several procedures for addressing the lower lids, the first and foremost being lower lid blepharoplasty. However, the remaining procedures combined with surgical techniques have exclusive implications in thick skin. Understanding the anatomy and various techniques that can be applied to thick skin can help achieve aesthetically more pleasing results in comparison to those of thin skin. As will be discussed in this article, patients with skin color of Fitzpatrick's grade III or higher have several characteristics associated with their skin, including thicker dermis as well as different patterns of aging, which have implications for addressing the lower lid complex. The senior author has extensive experience performing lower lid procedures and seeks to impart how best to understand and adapt for these differences to allow for the best aesthetic result.
Chronisches Nierenversagen – Update 2018
Authors: Ketteler Markus , Wanner Christoph
Published: February 2018

Was ist neu?

SGLT2-Hemmung bei diabetischer und nicht-diabetischer Nierenerkrankung Die CANVAS-Programm-Studie hat mit Canagliflozin die Nephroprotektion, welche mit Empagliflozin publiziert wurde (EMPA-REG-Outcome-Studie), bestätigt. Die Therapie mit Liraglutide in der LEADER Studie suggeriert Nephroprotektion über eine Reduktion der Albuminurie und geringerem eGFR-Abfall in Subgruppen/Stadien der diabetischen Nierenerkrankung.

KDIGO-CKD-MBD-Leitlinien-Update 2017 Im Juli 2017 erfolgte ein Update der KDIGO (Kidney Disease: Improving Global Outcomes) -2009-Leitlinie zur Diagnostik und Therapie der Störungen des Mineral- und Knochenhaushalts bei chronischen Nierenerkrankungen. Änderungen betrafen die Knochendichtemessung, die Therapie von Hyperphosphatämie und Hyperparathyreoidismus im Prädialysestadium und eine Warnung vor exzessiver Kalziumexposition.

Ein neues parenterales Kalzimimetikum Zwei Phase-III-Studien zum Einsatz eines neuen parenteralen Kalzimimetikums (Etelcalcitid) wurden publiziert.
Degradation analysis of an operating PV module on a Farm Sanctuary
Authors: Freire Felipe , Melcher Steve , Hochgraf Clark G. , Kurinec Santosh K.
Published: February 2018

Silicon photovoltaic (PV) modules are considered the most reliable component of a photovoltaic system and according to the manufacturers have a lifetime from 25 to 30 years. However, some modules degrade or fail along their service time under outdoor exposure and harsh conditions. The reliability and lifetime of a module depend on its energy conversion performance and degradation modes. For better understanding of the mechanisms behind the degradation and failure of PV modules, this study reviews the governing degradation modes and investigates a ten-year-old operating crystalline silicon PV module installed at an active farm and animal sanctuary. Field current-voltage testing and Infrared imaging for hot spot detection have been employed in examining this PV module showing localized damaged regions. While new remote sensing tools are being deployed to monitor large-scale PV systems, this study provides a basic overview of PV reliability to small-scale community users. This work exemplifies academic-community collaborations in the field of sustainability.
Impact of interstitial iron on the study of meta-stable B-O defects in Czochralski silicon: Further evidence of a single defect
Authors: Kim Moonyong , Chen Daniel , Abbott Malcolm , Nampalli Nitin , Wenham Stuart , Stefani Bruno , Hallam Brett
Published: February 2018

We explore the influence of interstitial iron (Fei) on lifetime spectroscopy of boron-oxygen (B-O) related degradation in p-type Czochralski silicon. Theoretical and experimental evidence presented in this study indicate that iron-boron pair (Fe-B) related reactions could have influenced several key experimental results used to derive theories on the fundamental properties of the B-O defect. Firstly, the presence of Fei can account for higher apparent capture cross-section ratios (k) of approximately 100 observed in previous studies during early stages of B-O related degradation. Secondly, the association of Fe-B pairs can explain the initial stage of a two-stage recovery of carrier lifetime with dark annealing after partial degradation. Thirdly, Fei can result in high apparent k values after the permanent deactivation of B-O defects. Subsequently, we show that a single k value can describe the recombination properties associated with B-O defects throughout degradation, that the recovery during dark annealing occurs with a single-stage, and both the fast- and slow-stage B-O related degradation can be permanently deactivated during illuminated annealing. Accounting for the recombination activity of Fei provides further evidence that the B-O defect is a single defect, rather than two separate defects normally attributed to fast-forming recombination centers and slow-forming recombination centers. Implications of this finding for the nature of the B-O defect are also discussed.
Propagation of THz acoustic wave packets in GaN at room temperature
Authors: Maznev A. A. , Hung T.-C. , Yao Y.-T. , Chou T.-H. , Gandhi J. S. , Lindsay L. , Shin H. D. , Stokes D. W. , Forrest R. L. , Bensaoula A. , Sun C.-K. , Nelson K. A.
Published: February 2018

We use femtosecond laser pulses to generate coherent longitudinal acoustic phonons at frequencies of 1–1.4 THz and study their propagation in GaN-based structures at room temperature. Two InGaN-GaN multiple-quantum-well (MQW) structures separated by a 2.3 μm-thick GaN spacer are used to simultaneously generate phonon wave packets with a central frequency determined by the period of the MQW and detect them after passing through the spacer. The measurements provide lower bounds for phonon lifetimes in GaN, which are still significantly lower than those from first principles predictions. The material Q-factor at 1 THz is found to be at least as high as 900. The measurements also demonstrate a partial specular reflection from the free surface of GaN at 1.4 THz. This work shows the potential of laser-based methods for THz range phonon spectroscopy and the promise for extending the viable frequency range of GaN-based acousto-electronic devices.
Internally coupled metamaterial beam for simultaneous vibration suppression and low frequency energy harvesting
Authors: Hu Guobiao , Tang Lihua , Das Raj
Published: February 2018

The paper proposes a modified metamaterial beam for simultaneous vibration suppression and energy harvesting. Local resonators in the modified metamaterial beam are alternately coupled, and each resonator is associated with a piezoelectric element for converting vibrations into electrical energy. First, the mathematical model of the modified metamaterial beam based piezoelectric energy harvester (PEH) is developed. The vibration suppression and energy harvesting performances of this system are analysed and compared with those of a conventional metamaterial beam PEH. The analytical results predict that not only the energy harvesting performance can be massively reinforced in the low frequency range, but also the vibration suppression performance can be slightly enhanced due to the appearance of an additional band gap. Subsequently, two finite element models, Models A and B, are developed. Model A is expected to be equivalent to the analytical model for validation and the local oscillators represented by lumped parameters in the analytical model are modelled by using cantilevers with tip masses. These tip masses are alternately coupled with ideal springs. The finite element analysis results in terms of both vibration suppression and energy harvesting show good agreement with the analytical results. Finally, to propose a more practical design of the internal coupling, Model B is established. Every two neighbouring tip masses are alternately coupled by using a beam connection. The finite element analysis results show that Model B is not completely equivalent to the proposed analytical model: no significant enhancement in terms of energy harvesting but a remarkably enhanced vibration suppression performance.
Comparison between Trichel pulse in negative corona and self-pulsing in other configurations
Authors: Xia Qing , Zhang Yu , He Feng , Qin Yu , Jiang Zhaorui , Ouyang Jiting
Published: February 2018

We present here a comparison study on self-pulsing phenomena in negative corona, hollow cathode discharges (HCD) and parallel-plate discharge in air. The voltage-current (V-I) curve, the waveforms of self-pulsed currents, and the time-resolved images of the pulsed discharge are measured under various operating conditions. It is experimentally evidenced that the Trichel pulse in a negative corona and the self-pulsing in HCD and/or parallel-plate discharge have similar features as well as spatial-temporal developing process. It is suggested that they should have a similar mechanism that the pulsing reflects the mode transition of discharge between the low-current Townsend and the high-current normal glow. The pulse rising corresponds to the breakdown and formation of temporal glow discharge in a background of low-current Townsend discharge, while the decay edge relates to the transition back to Townsend discharge. The pulse interval is the re-building process of the space charge layer of high density to ensure the glow breakdown.
Electronic and spectroscopic characterizations of SNP isomers
Authors: Trabelsi Tarek , Al Mogren Muneerah Mogren , Hochlaf Majdi , Francisco Joseph S.
Published: February 2018

High-level ab initio electronic structure calculations were performed to characterize SNP isomers. In addition to the known linear SNP, cyc-PSN, and linear SPN isomers, we identified a fourth isomer, linear PSN, which is located ∼2.4 eV above the linear SNP isomer. The low-lying singlet and triplet electronic states of the linear SNP and SPN isomers were investigated using a multi-reference configuration interaction method and large basis set. Several bound electronic states were identified. However, their upper rovibrational levels were predicted to pre-dissociate, leading to S + PN, P + NS products, and multi-step pathways were discovered. For the ground states, a set of spectroscopic parameters were derived using standard and explicitly correlated coupled-cluster methods in conjunction with augmented correlation-consistent basis sets extrapolated to the complete basis set limit. We also considered scalar and core-valence effects. For linear isomers, the rovibrational spectra were deduced after generation of their 3D-potential energy surfaces along the stretching and bending coordinates and variational treatments of the nuclear motions.
Effects of neutral distribution and external magnetic field on plasma momentum in electrodeless plasma thrusters
Authors: Takase Kazuki , Takahashi Kazunori , Takao Yoshinori
Published: February 2018

The effects of neutral distribution and an external magnetic field on plasma distribution and thruster performance are numerically investigated using a particle-in-cell simulation with Monte Carlo collisions (PIC-MCC) and the direct simulation Monte Carlo (DSMC) method. The modeled thruster consists of a quartz tube 1 cm in diameter and 3 cm in length, where a double-turn rf loop antenna is wound at the center of the tube and a solenoid is placed between the loop antenna and the downstream tube exit. A xenon propellant is introduced from both the upstream and downstream sides of the thruster, and the flow rates are varied while maintaining the total gas flow rate of 30 μg/s. The PIC-MCC calculations have been conducted using the neutral distribution obtained from the DSMC calculations, which were applied with different strengths of the magnetic field. The numerical results show that both the downstream gas injection and the external magnetic field with a maximum strength near the thruster exit lead to a shift of the plasma density peak from the upstream to the downstream side. Consequently, a larger total thrust is obtained when increasing the downstream gas injection and the magnetic field strength, which qualitatively agrees with a previous experiment using a helicon plasma source.
Giant excitation induced bandgap renormalization in TMDC monolayers
Authors: Meckbach L. , Stroucken T. , Koch S. W.
Published: February 2018

Optical absorption and gain spectra in MoS2 monolayers with thermal carrier distributions are calculated from the combined gap and Dirac-Bloch equations. It is shown that the excited carriers lead to a bandgap renormalization as large as 800 meV for a suspended monolayer MoS2. Above the critical density, optical gain is obtained over an approx. 400 meV broad spectral range above the gap. Whereas the absorption spectra in the low density regime are very sensitive to the dielectric environment, the spectra become purely intrinsic at elevated carrier densities.
Inclusion of orbital relaxation and correlation through the unitary group adapted open shell coupled cluster theory using non-relativistic and scalar relativistic Hamiltonians to study the core ionization potential of molecules containing light to medium-heavy elements
Authors: Sen Sangita , Shee Avijit , Mukherjee Debashis
Published: February 2018

The orbital relaxation attendant on ionization is particularly important for the core electron ionization potential (core IP) of molecules. The Unitary Group Adapted State Universal Coupled Cluster (UGA-SUMRCC) theory, recently formulated and implemented by Sen et al. [J. Chem. Phys. 137, 074104 (2012)], is very effective in capturing orbital relaxation accompanying ionization or excitation of both the core and the valence electrons [S. Sen et al., Mol. Phys. 111, 2625 (2013); A. Shee et al., J. Chem. Theory Comput. 9, 2573 (2013)] while preserving the spin-symmetry of the target states and using the neutral closed-shell spatial orbitals of the ground state. Our Ansatz invokes a normal-ordered exponential representation of spin-free cluster-operators. The orbital relaxation induced by a specific set of cluster operators in our Ansatz is good enough to eliminate the need for different sets of orbitals for the ground and the core-ionized states. We call the single configuration state function (CSF) limit of this theory the Unitary Group Adapted Open-Shell Coupled Cluster (UGA-OSCC) theory. The aim of this paper is to comprehensively explore the efficacy of our Ansatz to describe orbital relaxation, using both theoretical analysis and numerical performance. Whenever warranted, we also make appropriate comparisons with other coupled-cluster theories. A physically motivated truncation of the chains of spin-free T-operators is also made possible by the normal-ordering, and the operational resemblance to single reference coupled-cluster theory allows easy implementation. Our test case is the prediction of the 1s core IP of molecules containing a single light- to medium-heavy nucleus and thus, in addition to demonstrating the orbital relaxation, we have addressed the scalar relativistic effects on the accuracy of the IPs by using a hierarchy of spin-free Hamiltonians in conjunction with our theory. Additionally, the contribution of the spin-free component of the two-electron Gaunt term, not usually taken into consideration, has been estimated at the Self-Consistent Field (ΔSCF) level and is found to become increasingly important and eventually quite prominent for molecules with third period atoms and below. The accuracies of the IPs computed using UGA-OSCC are found to be of the same order as the Coupled Cluster Singles Doubles (ΔCCSD) values while being free from spin contamination. Since the UGA-OSCC uses a common set of orbitals for the ground state and the ion, it obviates the need of two N5 AO to MO transformation in contrast to the ΔCCSD method.
Excellent thermoelectric performance achieved over broad temperature plateau in indium-doped SnTe-AgSbTe2 alloys
Authors: He Mingkai , Feng Dan , Wu Di , Guan Yingdong , He Jiaqing
Published: February 2018

SnTe is deemed as a natural candidate to replace the state-of-the-art thermoelectric material PbTe, due to its low-cost, low-toxicity, and mechanical stability. Nevertheless, both the peak and average figure of merits of SnTe currently are way too inferior as compared to PbTe. In this work, we report that a peak figure of merit as high as ∼1.3 can be achieved at 873 K in p-type SnTe when it is simultaneously doped with Indium and alloyed with AgSbTe2. Moreover, the average figure of merit can be lifted astonishingly from 0.244 up to 0.84, by a factor of 344%, which is the record high value ever reported. The enhanced thermoelectric performance comes from a synergetic improvement of the power factor and reduction of lattice thermal conductivity. The former can be ascribed to the introduction of resonant states by Indium and probable regulation of the valence band structure by AgSbTe2 alloying, while the latter is believed to originate from the vast substitutional point defects at the Sn site by Ag and Sb substitution.
First reports of per- and poly-fluoroalkyl substances (PFASs) in Australian native and introduced freshwater fish and crustaceans
Authors: Taylor Matthew D.
Published: February 2018

Per- and poly-fluoroalkyl substances (PFASs) are persistent organic pollutants that have been extensively used in commercial and industrial applications, such as aqueous film-forming foam (AFFF) formulations. Widespread use of AFFFs has led to an increasing number of reports documenting PFAS contamination around civilian and military airports. However, research on the presence and distribution of PFASs in Australia is lacking. This study presents the first report of PFASs in Australian native and introduced freshwater species, sampled from a watercourse adjacent to the regional airport and colocated fire training ground near Tamworth, New South Wales, Australia. Perfluorooctane sulfonate was the most abundant PFAS compound in biota samples from this area, and both introduced common carp Cyprinus carpio and native Murray cod Maccullochella peelii had average concentrations higher than the Australian trigger value of 5.2μgkg–1. Common yabby Cherax destructor and golden perch Macquaria ambigua carried low concentrations, and common yabby also had low concentrations of perfluorohexane sulfonate. Differences in foraging habits provided some potential explanations of the differences observed among species. There is a clear and pressing need to better understand potential toxicological and reproductive effects of PFASs on Australian freshwater species.
Caspase-1 self-cleavage is an intrinsic mechanism to terminate inflammasome activity
Authors: Boucher Dave , Monteleone Mercedes , Coll Rebecca C. , Chen Kaiwen W. , Ross Connie M. , Teo Jessica L. , Gomez Guillermo A. , Holley Caroline L. , Bierschenk Damien , Stacey Katryn J. , Yap Alpha S. , Bezbradica Jelena S. , Schroder Kate
Published: February 2018

Host-protective caspase-1 activity must be tightly regulated to prevent pathology, but mechanisms controlling the duration of cellular caspase-1 activity are unknown. Caspase-1 is activated on inflammasomes, signaling platforms that facilitate caspase-1 dimerization and autoprocessing. Previous studies with recombinant protein identified a caspase-1 tetramer composed of two p20 and two p10 subunits (p20/p10) as an active species. In this study, we report that in the cell, the dominant species of active caspase-1 dimers elicited by inflammasomes are in fact full-length p46 and a transient species, p33/p10. Further p33/p10 autoprocessing occurs with kinetics specified by inflammasome size and cell type, and this releases p20/p10 from the inflammasome, whereupon the tetramer becomes unstable in cells and protease activity is terminated. The inflammasome–caspase-1 complex thus functions as a holoenzyme that directs the location of caspase-1 activity but also incorporates an intrinsic self-limiting mechanism that ensures timely caspase-1 deactivation. This intrinsic mechanism of inflammasome signal shutdown offers a molecular basis for the transient nature, and coordinated timing, of inflammasome-dependent inflammatory responses.
Picosecond laser micro/nano surface texturing of nickel for superhydrophobicity
Authors: Wang X C , Wang B , Xie H , Zheng H Y , Lam Y C
Published: February 2018

A single step direct picosecond laser texturing process was demonstrated to be able to obtain a superhydrophobic surface on a nickel substrate, a key material for mold fabrication in the manufacture of various devices, including polymeric microfluidic devices. A two-scale hierarchical surface structure of regular 2D array micro-bumps with nano-ripples was produced on a nickel surface. The laser textured surface initially showed superhydrophilicity with almost complete wetting of the structured surface just after laser treatment, then quickly changed to nearly superhydrophobic with a water contact angle (WCA) of 140° in less than 1 d, and finally became superhydrophobic with a WCA of more than 150° and a contact angle hysteresis (CAH) of less than 5°. The mechanism involved in the process is discussed in terms of surface morphology and surface chemistry. The ultra-fast laser induced NiO catalytic effect was thought to play a key role in modifying the surface chemistry so as to lower the surface energy. The developed process has the potential to improve the performance of nickel mold in the fabrication of microfluidic devices.
Kpax3: Bayesian bi-clustering of large sequence datasets
Authors: Pessia Alberto , Corander Jukka
Published: February 2018

Motivation

Estimation of the hidden population structure is an important step in many genetic studies. Often the aim is also to identify which sequence locations are the most discriminative between groups of samples for a given data partition. Automated discovery of interesting patterns that are present in the data can help to generate new biological hypotheses.

Results

We introduce Kpax3, a Bayesian method for bi-clustering multiple sequence alignments. Influence of individual sites will be determined in a supervised manner by using informative prior distributions for the model parameters. Our inference method uses an implementation of both split-merge and Gibbs sampler type MCMC algorithms to traverse the joint posterior of partitions of samples and variables. We use a large Rotavirus sequence dataset to demonstrate the ability of Kpax3 to generate biologically important hypotheses about differential selective pressures across a virus protein.

Availability and implementation

Kpax3 is implemented as a Julia package and released under the MIT license. Source code and documentation are available at: https://github.com/albertopessia/Kpax3.jl.

Supplementary information

Supplementary data are available at Bioinformatics online.
Improving SNP prioritization and pleiotropic architecture estimation by incorporating prior knowledge using graph-GPA
Authors: Kim Hang J , Yu Zhenning , Lawson Andrew , Zhao Hongyu , Chung Dongjun
Published: February 2018

Integration of genetic studies for multiple phenotypes is a powerful approach to improving the identification of genetic variants associated with complex traits. Although it has been shown that leveraging shared genetic basis among phenotypes, namely pleiotropy, can increase statistical power to identify risk variants, it remains challenging to effectively integrate genome-wide association study (GWAS) datasets for a large number of phenotypes. We previously developed graph-GPA, a Bayesian hierarchical model that integrates multiple GWAS datasets to boost statistical power for the identification of risk variants and to estimate pleiotropic architecture within a unified framework. Here we propose a novel improvement of graph-GPA which incorporates external knowledge about phenotype–phenotype relationship to guide the estimation of genetic correlation and the association mapping. The application of graph-GPA to GWAS datasets for 12 complex diseases with a prior disease graph obtained from a text mining of biomedical literature illustrates its power to improve the identification of risk genetic variants and to facilitate understanding of genetic relationship among complex diseases.

Availability and implementation

graph-GPA is implemented as an R package ‘GGPA’, which is publicly available at http://dongjunchung.github.io/GGPA/. DDNet, a web interface to query diseases of interest and download a prior disease graph obtained from a text mining of biomedical literature, is publicly available at http://www.chunglab.io/ddnet/.

Supplementary information

Supplementary data are available at Bioinformatics online.
ALMA [C i] observations toward the central region of Seyfert galaxy NGC 613
Authors: Miyamoto Yusuke , Seta Masumichi , Nakai Naomasa , Watanabe Yoshimasa , Salak Dragan , Ishii Shun
Published: February 2018

We report ALMA observations of [C i](3P1 − 3P0), 13CO, and C18O(J = 1–0) toward the central region of a nearby Seyfert galaxy NGC 613. The very high resolutions of 0${^{\prime\prime}_{.}}$26 × 0${^{\prime\prime}_{.}}$23 (=22 × 20 pc) for [C i] and 0${^{\prime\prime}_{.}}$42 × 0${^{\prime\prime}_{.}}$35 (=36 × 30 pc) for 13CO, and C18O resolve the circumnuclear disk (CND) and star-forming ring. The distribution of [C i] in the ring resembles that of the CO emission, although [C i] is prominent in the CND. This can be caused by the low intensities of the CO isotopes due to the low optical depths under the high temperature in the CND. We found that the intensity ratios of [C i] to 12CO(3–2) ($R_{\rm C\,{\small I}/CO}$) and to 13CO(1–0) ($R_{\rm C\,{\small I}/^{13}CO}$) are high at several positions around the edge of the ring. The spectral profiles of CO lines mostly correspond each other in the spots of the ring and high $R_{\rm C\,{\small I}/CO}$, but those of [C i] at spots of high $R_{\rm C\,{\small I}/CO}$ are different from those of CO. These results indicate that [C i] at the high $R_{\rm C\,{\small I}/CO}$ traces different gas from that traced by the CO lines. The [C i] kinematics along the minor axis of NGC 613 could be interpreted as a bubbly molecular outflow. The outflow rate of molecular gas is higher than star formation rate in the CND. The flow could be mainly boosted by the active galactic nucleus through its radio jets.
Acute Pain Assessment in Sedated Patients in the Postanesthesia Care Unit
Authors: Pereira-Morales Sherily , Arroyo-Novoa Carmen Mabel , Wysocki Annette , Sanzero Eller Lucille
Published: February 2018

Context:

Acute postoperative pain remains inadequately assessed and managed. A valid instrument that assesses acute pain in sedated postanesthesia care unit (PACU) patients is needed.

Objectives:

Two behavioral pain assessment instruments, the NonVerbal Pain Scale Revised (NVPS-R) and Critical-care Pain Observation Tool (CPOT), were used to determine whether these instruments adequately assess acute pain in the PACU.

Methods:

A crossover study design was used. The study was conducted in the Medical Services Administration at the Puerto Rico Medical Center. Upon PACU arrival, patient sedation levels were evaluated using the Richmond Agitation Sedation Scale. Acute pain was assessed using the CPOT (scored, 0 to 8) and the NVPS-R (scored, 0 to 10) at timepoints 0, 15, 30, 45, 60, 90, and 120 minutes. Descriptive statistics and mixed model regression analysis were used to compare pain score assessment between instruments.

Results:

Clinically significant increases in vital signs and respiratory indicators using the NVPS-R were not seen in patients with significant pain at time 0, 15, and 120 minutes. The CPOT vocalization indicator was more frequent in patients with significant pain.

Conclusions:

Findings suggest that NVPS-R and CPOT can assess acute pain in sedated PACU patients. In patients with significant pain, the CPOT vocalization indicator was more consistent than physiological and respiratory indicators in detecting acute pain. Thus, our data do not support the exclusive use of vital sign indicators to assess acute pain, suggesting the superiority of the CPOT for the assessment of acute pain in sedated PACU patients.
Equilibration Time Required for Respiratory System Compliance and Oxygenation Response Following Changes in Positive End-Expiratory Pressure in Mechanically Ventilated Children
Authors: Smallwood Craig D. , Walsh Brian K. , Arnold John H. , Gouldstone Andrew
Published: February 2018

Objectives:

Increases in positive end-expiratory pressure are implemented to improve oxygenation through the recruitment and stabilization of collapsed alveoli. However, the time it takes for a positive end-expiratory pressure change to have maximum effect upon oxygenation and pulmonary compliance has not been adequately described in children. Therefore, we sought to quantify the time required for oxygenation and pulmonary system compliance changes in children requiring mechanical ventilation.

Design:

Retrospective analysis of continuous data.

Settings:

Multidisciplinary ICU of a pediatric university hospital.

Patients:

Mechanically ventilated pediatric subjects.

Interventions:

A case was eligible for analysis if during a 90-minute window following an increase in positive end-expiratory pressure, no other changes to the ventilator were made, ventilator and physiologic data were continuously available and a positive oxygenation response was observed. Time to 90% (T90) of the maximum change in oxygenation and compliance was computed. Differences between oxygenation and compliance T90 were compared using a paired t test. The effect of severity of illness (by oxygen saturation index) upon oxygenation and compliance was analyzed.

Measurements and Main Results:

A total of 200 subjects were enrolled and 1,150 positive end-expiratory pressure change cases were analyzed. Of these, 54 subjects with 171 positive end-expiratory pressure change case were included in the analysis (67% were responders).

Changes in dynamic compliance (T90 = 38 min) preceded changes in oxygenation (T90 = 71 min; p < 0.001). Oxygenation response differed depending on severity of illness quantified by oxygen saturation index; lung dysfunction was associated with a longer response time (p = 0.001).

Conclusions:

T90 requires 38 and 71 minutes for dynamic pulmonary compliance and oxygenation, respectively; the latter was directly observed to be dependent upon severity of illness. To our knowledge, this is the first report of oxygenation and compliance equilibration data following positive end-expiratory pressure increases in pediatric mechanically ventilated subjects.
Fish/shellfish intake and the risk of head and neck cancer
Authors: McClain Kathleen M. , Bradshaw Patrick T. , Khankari Nikhil K. , Gammon Marilie D. , Olshan Andrew F.
Published: February 2018

Fish intake and other dietary sources of omega-3 fatty acids have been shown to be associated with a reduced risk for some cancers. Although previous studies of head and neck cancer have reported associations with different dietary factors, including reduced risks for fruits and vegetables and putatively healthy dietary patterns, associations specific to fish intake are unclear. This study investigated the association between fish/shellfish intake and risk of squamous cell carcinoma of the head and neck (SCCHN) using data from the Carolina Head and Neck Cancer Epidemiology Study, a population-based case–control study conducted in 46 North Carolina counties with cases recruited from 2002 through 2006. Controls were frequency matched to the cases on age, sex, and race; the final sample size was 1039 cases and 1375 controls. Demographic, lifestyle, and dietary information were collected using an in-person interviewer-administered structured questionnaire. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated with unconditional logistic regression. Patients whose fish/shellfish intake was among the highest tertile had a 20% lower odds of SCCHN compared with those in the lowest tertile (OR: 0.80; 95% CI: 0.60–1.07) after adjustment for the matching and other factors (income, energy intake, fruit intake, cigarette smoking, and alcohol intake). The inverse association was more pronounced for oral cavity and oropharyngeal tumors, for African Americans, and for females, but CIs were wide. To further investigate this potential risk reduction strategy for SCCHN, future studies should consider examining specific fish/shellfish, cooking practices, and other omega-3 fatty acid sources.
Molecular Biology of Exfoliation Syndrome
Authors: Schlötzer-Schrehardt Ursula
Published: February 2018

Exfoliation syndrome (XFS) is a common age-related matrix process resulting from excessive production and disordered assembly of elastic microfibrillar components into highly cross-linked fibrillary aggregates throughout the anterior eye segment and various organ systems. The underlying molecular pathophysiology involves a complex interplay of profibrotic protagonists including growth factors, proteolytic enzymes and inhibitors, proinflammatory cytokines, chaperones, and dysregulated stress response pathways including insufficient autophagy. Interaction between individual genetic predisposition and stress factors is a plausible theory explaining the development of XFS in the aging individual. Genome-wide association studies have identified robust genetic associations with LOXL1, CACNA1A, and 5 additional genes including POMP and TMEM136, which provide new biological insights into the pathology of XFS and highlight a role for abnormal matrix cross-linking processes, Ca2+ channel deficiency, blood-aqueous barrier dysfunction, and abnormal ubiquitin-proteasome signaling in XFS pathophysiology. However, the exact pathophysiological mechanisms, the functional role of genetic risk variants, and gene-environment interactions still remain to be characterized.
Laser Management of Glaucoma in Exfoliation Syndrome
Authors: Sandhu Simrenjeet , Damji Karim F.
Published: February 2018

Argon laser trabeculoplasty as well as selective laser trabeculoplasty can be used in patients with exfoliation syndrome with similar safety and efficacy. However, treatment effect may abruptly reverse and patients need to be followed regularly to monitor intraocular pressure control. Newer laser treatment modalities including micropulse laser trabeculoplasty, titanium sapphire laser trabeculoplasty and pattern scanning trabeculoplasty show promising results but need to be studied in exfoliation patients. For exfoliation patients with angle closure, peripheral iridectomy, iridoplasty or cataract extraction can be very helpful. For refractory exfoliation glaucoma, transscleral diode laser cyclophotocoagulation offers a reasonable option to lower intraocular pressure. Other approaches to cyclophotocoagulation such as micropulse transcleral diode laser need to be studied further in exfoliation patients.