bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural studies and physical properties of hexagonal-YbFeO3 thin films
Authors: Rai R. C. , Horvatits C. , Mckenna D. , Du Hart J.
Published: January 2019

We present structural, magnetic, and optical properties of multiferroic hexagonal YbFeO3 thin films, deposited on single crystal (001) Al2O3 and (111) ysz substrates by a magnetron sputtering system. Interestingly, the thermal stress affects YbFeO3 films on Al2O3 and ysz very differently. Although hexagonal-YbFeO3/Al2O3 films changed from a hexagonal to an orthorhombic phase due to annealing above 1000 °C, hexagonal-YbFeO3/ysz films remained mostly unaffected even after annealing at 1200 °C. The electronic excitations of the YbFeO3 thin films are dominated by Fe3+ d to d on-site electronic excitations as well as O 2p to Fe 3d, Yb 6s, and 5d charge-transfer excitations, and these excitations for hexagonal-YbFeO3 and orthorhombic-YbFeO3 thin films are distinctly different, consistent with the crystal field environments in the hexagonal and orthorhombic phases of YbFeO3. The room temperature energy band gaps of the hexagonal-YbFeO3 and orthorhombic-YbFeO3 thin films were measured to be ∼1.95 ± 0.05 eV and ∼2.40 ± 0.05 eV, respectively.
Wireless power transmission based on the double two-way spiral coil
Authors: Tian Zijian , Feng Liu , Gao Pengfei , He Fangyuan , Lin Yue
Published: January 2019

Magnetically coupled resonant (MCR) wireless power transmission (WPT) has the advantages of high efficiency, large transmission power and so on. It is suitable for medium-distance power supply. However, the traditional MCR WPT system based on the single one-way spiral coil (SOSC) will suffer frequency splitting due to the over-coupling between the transmitting and receiving coils during short-distance transmission. After analyzing the effect of coupling coefficient on the transmission efficiency of such systems, this paper proposed a double two-way spiral coil (DTSC) design method. This method used the structural features of the designed spiral coil to counteract the increased coupling coefficient due to short-distance transmission, thereby weakening the over-coupling between the transmitting coil and the receiving coil, narrowing the over-coupling region of the system, and compensating the effect of frequency splitting on the transmission efficiency during short-distance WPT. This method narrowed the system’s frequency splitting region and improved the system’s short-distance transmission efficiency. This paper analyzed the effect of the inner and the outer radius, the number of turns, and the pitch of the DTSC on the efficiency of the WPT system. This study showed that compared with the WPT system based on the SOSC, the WPT system based on the DTSC could narrow the frequency splitting region and significantly improve the short-distance transmission efficiency of the system. The correctness of the theoretical analysis has been verified by simulations and experiments.
Analysis of intersections of trajectories of systems of linear fractional differential equations
Authors: Deshpande Amey S. , Daftardar-Gejji Varsha , Vellaisamy P.
Published: January 2019

This article deals with trajectorial intersections in systems of linear fractional differential equations. We propose a classification of intersections of trajectories into three classes: (a) trajectories intersecting at the same time (IST), (b) trajectories intersecting at different times (IDT), and (c) self-intersections of a trajectory. We prove a generalization of the separation theorem for the case of linear fractional systems. This result proves the existence of the IST. Based on the presence of the IST, systems are further classified into two types, Type I and Type II systems, which are analyzed further for the IDT. Self-intersections in a fractional trajectory can be regular such as constant solution or limit-cycle behavior, or they can be irregular such as cusps or nodes. We give necessary and sufficient conditions for a trajectory to be regular.
State of charge and state of power management of the hybrid energy storage system in an architecture of microgrid
Authors: Bhowmik Pritam , Chandak Sheetal , Rout Pravat Kumar
Published: January 2019

This paper develops state variables for storage units and evaluates their performance in hybrid storage systems. To ensure an equalised storage utilisation factor, a self-tuned dynamic exponent controller is designed. The decentralised controller manages the state of charge within the high specific energy based hybrid storage units. Furthermore, to address the instability of the dc bus voltage, this paper proposes a fuzzy logic integrated dynamic PI based controller. The designed controller manages the state of power by regulating the compensation level of the high specific power based hybrid storage units during the transients. The improvement of the system stability through the proposed controllers is evaluated using the Nyquist stability criterion.
A modified approach for simulating electronically nonadiabatic dynamics via the generalized quantum master equation
Authors: Mulvihill Ellen , Schubert Alexander , Sun Xiang , Dunietz Barry D. , Geva Eitan
Published: January 2019

We present a modified approach for simulating electronically nonadiabatic dynamics based on the Nakajima-Zwanzig generalized quantum master equation (GQME). The modified approach utilizes the fact that the Nakajima-Zwanzig formalism does not require casting the overall Hamiltonian in system-bath form, which is arguably neither natural nor convenient in the case of the Hamiltonian that governs nonadiabatic dynamics. Within the modified approach, the effect of the nuclear degrees of freedom on the time evolution of the electronic reduced density operator is fully captured by a memory kernel super-operator. A methodology for calculating the memory kernel from projection-free inputs is developed. Simulating the electronic dynamics via the modified approach, with a memory kernel obtained using exact or approximate methods, can be more cost effective and/or lead to more accurate results than direct application of those methods. The modified approach is compared to previously proposed GQME-based approaches, and its robustness and accuracy are demonstrated on a benchmark spin-boson model with a memory kernel which is calculated within the Ehrenfest method.
Study of deep traps in AlGaN/GaN high-electron mobility transistors by electrical characterization and simulation
Authors: Ferrandis Philippe , El-Khatib Mariam , Jaud Marie-Anne , Morvan Erwan , Charles Matthew , Guillot Gérard , Bremond Georges
Published: January 2019

The localization of deep traps in normally-off AlGaN/GaN metal-oxide-semiconductor channel high-electron mobility transistors has been established by means of capacitance and current deep level transient spectroscopies (DLTS). Electrical simulations of the total current density between the drain and source contacts, the electron density, and the equipotential line distribution helped to understand the transport mechanisms into the device and to determine the zone probed by DLTS measurements. By changing the drain-source voltage in current DLTS or the reverse bias in capacitance DLTS, we demonstrated that we can choose to probe either the region below the gate or the region between the gate and drain electrodes. We could then see that defects related to reactive ion etching induced surface damage, expected to be formed during the gate recess process, were located only under the gate contact whereas native defects were found everywhere in the GaN layer. Thanks to this method of localization, we assigned a trap with an EC – 0.5 eV to ion etching induced damage.
High-Tc superconducting THz emitters fabricated by wet etching
Authors: Shibano Yuuki , Kashiwagi Takanari , Komori Yuki , Sakamoto Kazuki , Tanabe Yuki , Yamamoto Takashi , Minami Hidetoshi , Klemm Richard A. , Kadowaki Kazuo
Published: January 2019

We studied the etching of small crystals of the high-Tc superconductor Bi2Sr2CaCu2O8+δ (Bi2212) with various dilute compositions of hydrochloric and nitric acids. A particular mixture of those acids was chosen to simultaneously fabricate multiple rectangular stand-alone Bi2212 mesa structures from a large, doubly-cleaved and doubly metallic-coated single crystal. The radiation characteristics of these devices were found to be very similar to stand-alone devices fabricated previously using dry-etching techniques. The greatly reduced time and cost of fabrication of stand-alone Bi2212 devices using our wet-etching technique should facilitate the mass production of a large number of identical stand-alone devices from a large single-crystalline Bi2212 substrate.
Machine learning methods for turbulence modeling in subsonic flows around airfoils
Authors: Zhu Linyang , Zhang Weiwei , Kou Jiaqing , Liu Yilang
Published: January 2019

In recent years, the data-driven turbulence model has attracted widespread concern in fluid mechanics. The existing approaches modify or supplement the original turbulence model by machine learning based on the experimental/numerical data, in order to augment the capability of the present turbulence models. Different from the previous researches, this paper directly reconstructs a mapping function between the turbulent eddy viscosity and the mean flow variables by neural networks and completely replaces the original partial differential equation model. On the other hand, compared with the machine learning models for the low Reynolds (Re) number flows based on direct numerical simulation data, high Reynolds number flows around airfoils present the apparent scaling effects and strong anisotropy, which induce large challenges in accuracy and generalization capability for the machine learning algorithm. We mainly concentrate on the high Reynolds number turbulent flows around the airfoils and take the results calculated by the computational fluid dynamics solver with the Spallart-Allmaras (SA) model as training data to construct a high-dimensional data-driven network model based on machine learning. The radial basis function neural network and the auxiliary optimization methods are adopted, and the individual models are built separately for the flow fields of the near-wall region, wake region, and far-field region. The training data in this paper is extracted from only three subsonic flow fields of NACA0012 airfoil. The data-driven turbulence model can be applied to various airfoils and flow states, and the predicted eddy viscosity, lift/drag coefficients, and skin friction distributions are all in good agreement with the results of the original SA model. This research demonstrates the promising prospect of machine learning methods in future studies about turbulence modeling.
Improved model of ionic transport in 2-D MoS2 membranes with sub-5 nm pores
Authors: Pérez María Daniela Barrios , Nicolaï Adrien , Delarue Patrice , Meunier Vincent , Drndić Marija , Senet Patrick
Published: January 2019

Solid-state nanopores made of two-dimensional materials such as molybdenum disulfide are of great interest thanks in part to promising applications such as ion filtration and biomolecule translocation. Controlled fabrication and tunability of nanoporous membranes require a better understanding of their ionic conductivity capabilities at the nanoscale. Here, we developed a model of ionic conductivity for a KCl electrolyte through sub 5-nm single-layer MoS2 nanopores using equilibrium all-atom molecular dynamics simulations. We investigate the dynamics of K+ and Cl− ions inside the pores in terms of concentration and mobility. We report that, for pore dimensions below 2.0 nm, which are of particular interest for biomolecule translocation applications, the behaviors of the concentration and mobility of ions strongly deviate from bulk properties. Specifically, we show that the free-energy difference for insertion of an ion within the pore is proportional to the inverse surface area of the pore and that the inverse mobility scales linearly as the inverse diameter. Finally, we provide an improved analytical model taking into account the deviation of ion dynamics from bulk properties, suitable for direct comparison with experiments.
Improvement of the pinning property in YBa2Cu3O7−

x
films below 35 K by doping with graphene oxide
Authors: Wang Jun , Zhang Qiangqiang , Liu Cong , Zhang Xingyi
Published: January 2019

Pinning induction in REBa2Cu3O7−x (RE = rare earth) films and coated conductors improves their critical current density (Jc). In general, however, interstitial elements, e.g., C and N, cannot act as effective pinning centers in REBa2Cu3O7−x materials because they typically lead to degeneration of the superconducting properties. In this work, the influence of graphene oxide (GO) on YBa2Cu3O7−x (YBCO) films was studied by measuring the critical temperature and angle-dependent critical current density. The results revealed that the concentration of GO in YBCO films modulated the critical temperature. The decay rate of Jc in H∥c field orientations decreased with decreasing temperature. At 35 K and 4.2 K, the YBCO/GO film exhibited a lower decay of Jc and less anisotropic behavior than the YBCO-BaMO3 (M = Zr, Hf) film. GO doping could, therefore, improve the pinning property of YBCO films below 35 K. This improvement could be due to the presence of nanosized carbon structures, which served as isotropic pinning centers at low temperature, as revealed by high-resolution transmission electron microscopy.
Probing alkenoxy radical electronic structure using anion PEI spectroscopy
Authors: Patros Kellyn M. , Mann Jennifer E. , Dobulis Marissa A. , Thompson Michael C. , Jarrold Caroline Chick
Published: January 2019

Photoelectron imaging spectra of three alkenoxide radical anions (3-buten-1-oxide, 3-buten-2-oxide, and 2-propenoxide) are presented and analyzed with supporting results of density functional theory calculations. In all spectra, intense detachment features are observed at approximately 2 eV electron binding energy, which is similar to the electron affinities of saturated neutral alkoxy radicals [Ramond et al., J. Chem. Phys. 112, 1158 (2000)]. Photoelectron angular distributions suggest the presence of several overlapping transitions which are assigned to the X̃ and Ã states of multiple energetically competitive conformers. The term energy of the Ã state of the 2-propenoxy radical, 0.17 eV, is higher than that of 3-buten-2-oxy (0.13 eV) and 3-buten-1-oxy (0.05 eV) radicals. Comparing the butenoxy radicals, we infer that stronger interactions between the non-bonding O 2p orbitals and the π bond increase the splitting between the ground and the first excited state in the 3-buten-2-oxy radical relative to the 3-buten-1-oxy radical.
On the correlation between topological defects of polarization field and Euler characteristics of ferroelectric nanostructures
Authors: Van Lich Le , Ton Quang-Thang , Nguyen Trong-Giang , Dinh Van-Hai
Published: January 2019

Materials with spatial-reversal broken symmetry such as ferroelectrics rarely exhibit topological field patterns, in contrast to time-reversal broken symmetry materials. Recently, geometrical confinements at the nanoscale are demonstrated to play an important role in the stabilization of nontrivial topological polarization patterns in ferroelectrics; however, a direct correlation between them remains hidden. In the present study, we establish a correlation between the topology of finite nanostructures and the topology of polarization fields through phase-field simulations and topological theory of defects. The obtained results show that ferroelectric nanostructures can exhibit stable topological defects in their polar patterns that are composed of topological bulk and edge defects with an integer and fractional winding numbers, respectively. In addition, we demonstrate that topological characteristics of polarization patterns are conserved, regardless of the structure transformation and external electric and mechanical fields. Such conserved topological defects in polarization patterns consistently relate to the Euler characteristics of ferroelectric nanostructures. Furthermore, we propose and prove a concept for geometry-mediated trapping of local topological defects in ferroelectric nanostructures, where defects can be intentionally tailored through a geometrical design.
Transmitters and receivers in SiGe BiCMOS technology for sensitive gas spectroscopy at 222 - 270 GHz
Authors: Schmalz K. , Rothbart N. , Eissa M. H. , Borngräber J. , Kissinger D. , Hübers H.-W.
Published: January 2019

This paper presents transmitter and receiver components for a gas spectroscopy system. The components are fabricated in IHP’s 0.13 μm SiGe BiCMOS technology. Two fractional-N phase-locked loops are used to generate dedicated frequency ramps for the transmitter and receiver and frequency shift keying for the transmitter. The signal-to-noise ratio (SNR) for the absorption line of gaseous methanol (CH3OH) at 247.6 GHz is used as measure for the performance of the system. The implemented mixer-first receiver allows a high performance of the system due to its linearity up to an input power of -10 dBm. Using a transmitter-array with an output power of 7 dBm an SNR of 4660 (integration time of 2 ms for each data point) was obtained for the 247.6 GHz absorption line of CH3OH at 5 Pa. We have extended our single frequency-band system for 228 – 252 GHz to a 2-band system to cover the range 222 – 270 GHz by combining corresponding two transmitters and receivers with the frequency bands 222 – 256 GHz and 250 – 270 GHz on single transmitter- and receiver-chips. This 2-band operation allows a parallel spectra acquisition and therefore a high flexibility of data acquisition for the two frequency-bands. The 50 GHz bandwidth allows for highly specific and selective gas sensing.
Three-dimensional fluid simulations of the Cs plasma release in the ionosphere
Authors: Zhang Xing , Sun Anbang , Tian Le , Zhang Guanjun
Published: January 2019

Releasing plasma cloud is an efficient way to manage ionosphere properties. In this paper, we establish a three-dimensional fluid model to simulate the spatiotemporal evolution of released Cs plasma. Four types of particles are taken into account: released neutral Cs, ambient O, Cs+ and electron, among which the Cs+ and electron move according to the classical ambipolar diffusion. Meanwhile, photoionization induced by solar radiation and recombination of Cs+/electron are included in model as two chemical reactions. Based on this model, we investigate the influence of three factors: initial velocity of neutral Cs cloud, photoionization rate and altitude. The initial velocity can change the whole distribution of plasma cloud. When there is no velocity or velocity along the background magnetic field, the plasma cloud shows an ellipsoid shape and moves with neutral cloud. If the velocity is perpendicular to the magnetic field line, the cloud will be stretched in the same direction and does not move. We investigate the influence of photoionization rate under different initial velocities, and find that with the photoionization rate increasing, more and more particles remain in the initial release position. Moreover, the altitude affects the density of ambient O and temperature result in the diffusion coefficient and drifting velocity reducing and then the size of bulk plasma inclines to be reduced at lower altitude.
On the closure problem of the effective stress in the Eulerian-Eulerian and mixture modeling approaches for the simulation of liquid-particle suspensions
Authors: Jamshidi Rashid , Angeli Panagiota , Mazzei Luca
Published: January 2019

We address the closure problem of the phasic effective stress tensors in the Eulerian-Eulerian and mixture models, considering suspensions of identical particles dispersed in Newtonian liquids. First, after briefly describing the modeling approaches, we review the key mechanisms generating phasic stress and discuss the shortcomings of some constitutive expressions in reproducing important experimental observations. For dilute suspensions, these include the mixture viscosity rise with solid concentration whilst for dense suspensions, the occurrence of particle migration and the change of mixture rheology from Newtonian to non-Newtonian. We then use computational fluid dynamics simulations to compare results based on various stress tensor closures. In a first case study, the simulation results of a laminar flow in a horizontal pipe of a dilute suspension of particles dispersed in a Newtonian liquid are compared to experimental data obtained from the literature. We show that both the Eulerian-Eulerian and mixture models can predict pressure drops accurately but only if they are coupled with suitable experimental closures for the mixture rheology. In a second case study, we simulate the laminar flow of a dense suspension of identical particles dispersed in a Newtonian liquid through an abrupt expansion. We show that the particle concentration profile in the upstream tube, which develops owing to shear-induced particle migration, strongly affects the flow patterns downstream of the expansion. This migration must be modeled via an appropriate closure for the solid effective stress tensor; this allows capturing the sophisticated flow patterns in the expansion section.
Understanding and protecting against backscattered light in high-power laser systems
Authors: Yiu Yuen
Published: January 2019

Computer-simulated burn patterns from backscattered light during laser experiments may help mitigate damage in optical assemblies at high-power laser facilities.
Using Thermodynamics to Assess the Molecular Interactions of Tetrabutylphosphonium Carboxylate–Water Mixtures
Authors: Yeadon Darius J. , Jacquemin Johan , Plechkova Natalia V. , Gomes Margarida Costa , Seddon Kenneth R.
Published: January 2019

Densities, ρ, viscosities, η, and enthalpies of mixing, , of binary [P4 4 4 4][CnCOO]–water mixtures (with n=1, 2 or 7) were determined at atmospheric pressure as a function of temperature. The excess, , apparent, , and partial, , molar volumes were deduced from experimental data, as well as fragilities, m*, and excess Gibbs free energies of activation of viscous flow, . exhibited predominantly negative deviation from ideality, with a minimum at approximately ~0.8 for all three systems, indicating strong hydrogen-bonding interactions. All three binary systems were found to be fragile, with [P4 4 4 4][C7COO] showing the smallest deviations in fragility with the addition of water. values of the systems were exothermic over the entire composition range, having the following trend: [P4 4 4 4][C2COO]>[P4 4 4 4][C7COO]>[P4 4 4 4][C1COO].
Saccharopine, a lysine degradation intermediate, is a mitochondrial toxin
Authors: Leandro João , Houten Sander M.
Published: January 2019

Saccharopine, a nonproteinogenic amino acid originally isolated from the yeast Saccharomyces cerevisiae, is an intermediate in lysine metabolism. In this issue, Zhou et al. (2019. J. Cell Biol. https://doi.org./10.1083/jcb.201807204) show that abnormal accumulation of saccharopine results in defective mitochondrial dynamics and function in worm and mouse models.
Dual binding motifs underpin the hierarchical association of perilipins1–3 with lipid droplets
Authors: Ajjaji Dalila , Ben M'barek Kalthoum , Mimmack Michael L. , England Cheryl , Herscovitz Haya , Dong Liang , Kay Richard G. , Patel Satish , Saudek Vladimir , Small Donald M. , Savage David B. , Thiam Abdou Rachid
Published: January 2019

Lipid droplets (LDs) in all eukaryotic cells are coated with at least one of the perilipin (Plin) family of proteins. They all regulate key intracellular lipases but do so to significantly different extents. Where more than one Plin is expressed in a cell, they associate with LDs in a hierarchical manner. In vivo, this means that lipid flux control in a particular cell or tissue type is heavily influenced by the specific Plins present on its LDs. Despite their early discovery, exactly how Plins target LDs and why they displace each other in a “hierarchical” manner remains unclear. They all share an amino-terminal 11-mer repeat (11mr) amphipathic region suggested to be involved in LD targeting. Here, we show that, in vivo, this domain functions as a primary highly reversible LD targeting motif in Plin1–3, and, in vitro, we document reversible and competitive binding between a wild-type purified Plin1 11mr peptide and a mutant with reduced binding affinity to both “naked” and phospholipid-coated oil–water interfaces. We also present data suggesting that a second carboxy-terminal 4-helix bundle domain stabilizes LD binding in Plin1 more effectively than in Plin2, whereas it weakens binding in Plin3. These findings suggest that dual amphipathic helical regions mediate LD targeting and underpin the hierarchical binding of Plin1–3 to LDs.
A computational model of the early stages of acentriolar meiotic spindle assembly
Authors: Letort Gaelle , Bennabi Isma , Dmitrieff Serge , Nedelec François , Verlhac Marie-Hélène , Terret Marie-Emilie
Published: January 2019

The mitotic spindle is an ensemble of microtubules responsible for the repartition of the chromosomal content between the two daughter cells during division. In metazoans, spindle assembly is a gradual process involving dynamic microtubules and recruitment of numerous associated proteins and motors. During mitosis, centrosomes organize and nucleate the majority of spindle microtubules. In contrast, oocytes lack canonical centrosomes but are still able to form bipolar spindles, starting from an initial ball that self-organizes in several hours. Interfering with early steps of meiotic spindle assembly can lead to erroneous chromosome segregation. Although not fully elucidated, this process is known to rely on antagonistic activities of plus end– and minus end–directed motors. We developed a model of early meiotic spindle assembly in mouse oocytes, including key factors such as microtubule dynamics and chromosome movement. We explored how the balance between plus end– and minus end–directed motors, as well as the influence of microtubule nucleation, impacts spindle morphology. In a refined model, we added spatial regulation of microtubule stability and minus-end clustering. We could reproduce the features of early stages of spindle assembly from 12 different experimental perturbations and predict eight additional perturbations. With its ability to characterize and predict chromosome individualization, this model can help deepen our understanding of spindle assembly.
Developing an antimicrobial stewardship program across a rural health system: The Avera Health experience
Authors: Laible Brad R , Grosdidier Jamie , Nazir Jawad
Published: January 2019

Purpose

The stages of development of a health system–wide antimicrobial stewardship program (ASP) using existing personnel and technology are described.

Small hospitals with limited resources may struggle to meet ASP requirements, particularly facilities without onsite infectious disease physicians and/or experienced infectious disease pharmacists. Strategies for ASP development employed by Avera Health, a 33-hospital health system in the Midwest, included identifying relevant drug utilization and resistance patterns, education and pathway development, and implementation of Web-based conferencing to provide pharmacists throughout the system with access to infectious disease expertise on a daily basis. These efforts resulted in an evolving single-system ASP that has leveraged existing resources to overcome some system barriers. Program outcomes to date include a reduction in the use of a targeted agent, improved pathogen susceptibility trends, and rates of hospital-associated Clostridium difficile infection below national benchmarks.

Conclusion

The Avera Health ASP grew from a collaborative project targeting levofloxacin overuse and resistance among key bacteria to a formal, health system–wide ASP in a rural setting. This program used existing personnel to provide standardized processes, educational campaigns, and antimicrobial expertise through the use of technology. This ASP program may provide helpful examples of ASP strategies for other rural health systems with similar resources.
Reducing time to pregnancy and facilitating the birth of healthy children through functional analysis of embryo physiology†
Authors: Ferrick Laura , Lee Yee Shan Lisa , Gardner David K
Published: January 2019

An ever-increasing number of couples rely on assisted reproductive technologies (ART) in order to conceive a child. Although advances in embryo culture have led to increases in the success rates of clinical ART, it often takes more than one treatment cycle to conceive a child. Ensuring patients conceive as soon as possible with a healthy embryo is a priority for reproductive medicine. Currently, selection of embryos for transfer relies predominantly on the morphological assessment of the preimplantation embryo; however, morphology is not an absolute link to embryo physiology, nor the health of the resulting child. Non-invasive quantitation of individual embryo physiology, a key regulator of both embryo viability and health, could provide valuable information to assist in the selection of the most viable embryo for transfer, hence reducing the time to pregnancy. Further, according to the Barker Hypothesis, the environment to which a fetus is exposed to during gestation affects subsequent offspring health. If the environment of the preimplantation period is capable of affecting metabolism, which in turn will affect gene expression through the metaboloepigenetic link, then assessment of embryo metabolism should represent an indirect measure of future offspring health. Previously, the term viable embryo has been used in association with the potential of an embryo to establish a pregnancy. Here, we propose the term healthy embryo to reflect the capacity of that embryo to lead to a healthy child and adult.
‘Personal’ troubles and public spaces: the community as a site of care and social action
Authors: Crean Mags
Published: January 2019

The crisis in community development in Ireland has been discussed by community workers, academics and equality experts. This article contributes to this analysis with empirical research encompassing the voice of people living with inequality, including a number of community activists. The research shows how affective relations take precedence in women’s discussions about social class inequality and activism at a community level. Yet, this everyday concern with the affective is not given a legitimate status in academic and political discourse about community development. It is argued that this depoliticization of affective relations is part of the crisis in community development when it fails to incorporate a political analysis of what matters most to people at a community level.
A Novel Olfactometer for Efficient and Flexible Odorant Delivery
Authors: Burton Shawn D , Wipfel Mia , Guo Michael , Eiting Thomas P , Wachowiak Matt
Published: January 2019

Understanding how sensory space maps to neural activity in the olfactory system requires efficiently and flexibly delivering numerous odorants within single experimental preparations. Such delivery is difficult with current olfactometer designs, which typically include limited numbers of stimulus channels and are subject to intertrial and interchannel contamination of odorants. Here, we present a novel olfactometer design that is easily constructed, modular, and capable of delivering an unlimited number of odorants in air with temporal precision and no detectable intertrial or interchannel contamination. The olfactometer further allows for the flexible generation of odorant mixtures and flexible timing of odorant sequences. Odorant delivery from the olfactometer is turbulent but reliable from trial to trial, supporting operant conditioning of mice in an odorant discrimination task and permitting odorants and concentrations to be mapped to neural activity with a level of precision equivalent to that obtained with a flow dilution olfactometer. This novel design thus provides several unique advantages for interrogating olfactory perception and for mapping sensory space to neural activity in the olfactory system.
Long-term outcome of third, fourth and fifth kidney transplantation: technical aspects and immunological challenges
Authors: Benkö Tamas , Halfmann Patrizia , Gäckler Anja , Radünz Sonia , Treckmann Jürgen W , Kaiser Gernot M , Hoyer Dieter P
Published: January 2019

Background

The number of patients on waiting lists for repeated kidney transplantation has increased. However, retransplanted patients have a greater surgical and immunological risk than first-time kidney recipients.

Methods

We retrospectively analysed all kidney recipients that underwent third, fourth or fifth kidney transplantation (Group 3+) at the University Hospital Essen, Essen, Germany from October 1973 to January 2017. A historical cohort of recipients retransplanted with a second kidney (Group 2) served as the control. Donor and recipient demographic data, cold ischaemia time (CIT), warm ischaemia time, overall operation time and methods, transplantectomy of previous kidney grafts, incidence of surgical and immunological complications as well as patient- and death-censored survival were analysed.

Results

We identified 108 recipients transplanted with the third, fourth or fifth renal allograft. Patients with more than one transplantation had significantly higher surgical risk due to atherosclerosis (P = 0.002) and higher immunological risk due to higher panel reactive antibody levels preoperatively (current panel reactive antibody P = 0.004; highest panel reactive antibody value P = 0.0001). Group 3+ patients had more often undergone previous transplant nephrectomy (P = 0.0001). There was a significant difference in CIT (P = 0.009), overall operative time (P = 0.0001) and post-transplantation thrombotic events (P = 0.02). We could not demonstrate any differences in graft and patient survival.

Conclusion

Third, fourth and fifth transplant recipients are a high-risk patient cohort. Our results suggest that patient survival after more than three renal transplantations is similar to that of second graft recipients. This supports the concept of repeated kidney retransplantations.
Fluoroquinolone resistance in carbapenem-resistant Elizabethkingia anophelis: phenotypic and genotypic characteristics of clinical isolates with topoisomerase mutations and comparative genomic analysis
Authors: Jian Ming-Jr , Cheng Yun-Hsiang , Chung Hsing-Yi , Cheng Yu-Hsuan , Yang Hung-Yi , Hsu Chih-Sin , Perng Cherng-Lih , Shang Hung-Sheng
Published: January 2019

Background

MDR Elizabethkingia anophelis strains are implicated in an increasing number of healthcare-associated infections worldwide, including a recent cluster of E. anophelis infections in the Midwestern USA associated with significant morbidity and mortality. However, there is minimal information on the antimicrobial susceptibilities of E. anophelis strains or their antimicrobial resistance to carbapenems and fluoroquinolones.

Objectives

Our aim was to examine the susceptibilities and genetic profiles of clinical isolates of E. anophelis from our hospital, characterize their carbapenemase genes and production of MBLs, and determine the mechanism of fluoroquinolone resistance.

Methods

A total of 115 non-duplicated isolates of E. anophelis were examined. MICs of antimicrobial agents were determined using the Sensititre 96-well broth microdilution panel method. QRDR mutations and MBL genes were identified using PCR. MBL production was screened for using a combined disc test.

Results

All E. anophelis isolates harboured the blaGOB and blaB genes with resistance to carbapenems. Antibiotic susceptibility testing indicated different resistance patterns to ciprofloxacin and levofloxacin in most isolates. Sequencing analysis confirmed that a concurrent GyrA amino acid substitution (Ser83Ile or Ser83Arg) in the hotspots of respective QRDRs was primarily responsible for high-level ciprofloxacin/levofloxacin resistance. Only one isolate had no mutation but a high fluoroquinolone MIC.

Conclusions

Our study identified a strong correlation between antibiotic susceptibility profiles and mechanisms of fluoroquinolone resistance among carbapenem-resistant E. anophelis isolates, providing an important foundation for continued surveillance and epidemiological analyses of emerging E. anophelis opportunistic infections. Minocycline or ciprofloxacin has the potential for treatment of severe E. anophelis infections.
Multilocus phylogeny, species delimitation and biogeography of Iberian valvatiform springsnails (Caenogastropoda: Hydrobiidae), with the description of a new genus
Authors: Delicado Diana , Arconada Beatriz , Aguado Amanda , Ramos Marian A
Published: January 2019

Valvatiform gastropods of the family Hydrobiidae are frequently found in European spring-fed systems. Their simplified and sometimes convergent morphological structures and restricted geographical ranges make the description and identification of valvatiform species challenging. In the Iberian Peninsula, to date, 20 valvatiform species have been described morphologically. To test morphological species delimitations and to evaluate the role of physical geography on their evolutionary history, we analysed two mitochondrial (COI and 16S rRNA) and two nuclear (28S rRNA and 18S rRNA) gene fragments of 16 valvatiform species from the Iberian Peninsula. Molecular species delimitation methods consistently inferred 11 of the nominal species. Our phylogenetic analyses recovered the species Islamia azarum as an independent lineage, distantly related to other genera, which we place in the new genus Deganta. Furthermore, Iberian valvatiform hydrobiids do not form a monophyletic subunit, but they are included in two distinct clades of Hydrobiidae. Divergence times indicate that speciation in these clades is likely to have coincided with the formation of major Iberian mountain ranges and river basins. Similarities of geographical subdivision and divergent times between this assemblage and the non-valvatiform genus Corrosella provide strong evidence for the role of the Iberian geographical barriers in shaping the biogeography of these springsnails.
Effects of the Endophytic BacteriaBacillus cereusBCM2 on Tomato Root Exudates andMeloidogyne incognitaInfection
Authors: Li Xia , Hu Hai-Jing , Li Jing-Yu , Wang Cong , Chen Shuang-Lin , Yan Shu-Zhen
Published: January 2019

Root-knot nematodes (Meloidogyne spp.) cause serious crop losses worldwide. The colonization of tomato roots by endophytic bacteria Bacillus cereus BCM2 can greatly reduce Meloidogyne incognita damage, and tomato roots carrying BCM2 were repellent to M. incognita second-stage juveniles (J2). Here, the effects of BCM2 colonization on the composition of tomato root exudates was evaluated and potential mechanisms for BCM2-mediated M. incognita control explored using a linked twin-pot assay and GC-MS. On water agar plates, J2 preferentially avoided filter paper treated with tomato root exudates (organic phase only) from plants inoculated with BCM2, visiting these 67.1% less than controls. In a linked twin-pot assay, BCM2 treatment resulted in a 42.0% reduction in the number of nematodes in the soil, a 43.3% reduction in the number of galls and a 47.7% decrease in the density of M. incognita in root tissues. Analysis of root exudate composition revealed that BCM2 inoculation increased the number of components in exudates. Among these, 2,4-di-tert-butylphenol, 3,3-dimethyloctane, and n-tridecane secretions markedly increased. In repellency trials on water agar plates, J2 avoided 2,4-di-tert-butylphenol, n-tridecane, and 3,3-dimethyloctane at concentrations of 4 mmol/liter. In a linked twin-pot assay, inoculation with 2,4-di-tert-butylphenol or 3,3-dimethyloctane reduced the number of nematodes in the soil (by 54.9 and 70.6%, respectively), the number of galls (by 53.7 and 52.4%), and the number of M. incognita in root tissues (by 67.5 and 36.3%). BCM2 colonization in tomato roots affected the composition of root exudates, increasing the secretion of substances that appear to be repellent, thus decreasing M. incognita J2 infection of roots.
Single inhaler maintenance and reliever therapy in pediatric asthma
Authors: Nalin Ug , Stout Sean , Portnoy Jay M.
Published: January 2019

Purpose of review

Asthma affects more than 25 million people worldwide and continues to grow in prevalence. According to a center for disease control and prevention (CDC) report, the total annual cost of asthma in the United States between 2008 and 2013, including medical care, absenteeism, and mortality, was $81.9 billion. Although the National Institute of Health guidelines recommend fixed inhaled corticosteroid (ICS) dosing, the 2008–2010 Medical Expenditure Panel Survey showed that asthma is still poorly controlled. Single inhaler maintenance and reliever therapy (SMART) offers a possible alternative management plan. This is a review of SMART vs. current treatment guidelines.

Recent findings

SMART addresses variable inflammation with symptom-driven dosing of ICS. It relies on a combination inhaler that has a long-acting β-agonist, which has an immediate onset of action to provide quick relief, in combination with an ICS. Recent studies show that SMART decreases the frequency and severity of asthma exacerbations when compared to fixed ICS dosing. In addition, intermittent use of ICS gave a reduced effect on growth and permitted a lower total amount of ICS to be delivered.

SMART appears to outperform treatment that is based on current guidelines in the United States. As inhalers capable of being used for SMART are already approved, what is needed is Food and Drug Administration approval of the SMART strategy.
Aligning Delivery System and Training Missions in Academic Medical Centers to Promote High-Value Care
Authors: Gupta Reshma , Sehgal Niraj , Arora Vineet M.
Published: January 2019

Academic medical centers (AMCs) are transforming to improve their care delivery and learning environments so that they build a culture that fosters high-value care. However, AMCs struggle to create learning environments where trainees are part of the reason for institutional success and their initiatives have high impact and are sustainable. The authors believe that AMCs can reach these goals if they codevelop strategic priorities and provide infrastructure to support alignment between the missions of health delivery systems and graduate medical education (GME).

They outline four steps for AMCs and policy makers to create an infrastructure that supports this alignment to deliver value-based care. First, AMCs can align strategic priorities between delivery systems and educators by creating a common understanding of why initiatives require priorities within the health care system. Second, AMCs can support alignment with data from multiple sources that are reliable, valid, and actionable for trainees. Third, resident initiatives can create sustained impact by linking trainees to the institutional staff and infrastructure supporting value improvement efforts. Fourth, incentive payment programs through medical education could augment current system incentives to propel further alignment between education and delivery systems. The authors support their recommendations with concrete examples from emerging models created by GME and health delivery system leaders at AMCs across the country.
Medical Students’ Perceptions of and Responses to Health Care Disparities During Clinical Clerkships
Authors: Glaser Johanna , Pfeffinger Alana , Quan Judy , Fernandez Alicia
Published: January 2019

Purpose

To measure the frequency and nature of student-perceived clinician-driven health care disparities, and determine their impact on medical students’ professional development.

Method

Retrospective study of fourth-year medical students at the University of California, San Francisco School of Medicine, August 2016 to June 2017. Conducted via an electronic survey asking about frequency/nature of directly witnessed health care disparities and barriers/facilitators to action during third-year clerkships; and individual, semistructured interviews focusing on clinical details and impact on students’ professional development.

Results

Respondents were 103/159 students (65%). In internal medicine clerkships, a majority perceived disparities as occurring sometimes (2–7 times in eight-week clerkship) or often (at least once weekly or nearly daily) based on language barriers (90%), patients’ homelessness (77%), history of substance abuse (76%), obesity (67%), and race/ethnicity: Latino (72%), black (71%), and Asian (56%). Results from other clerkships were similar. Barriers to student action to perceived disparities included fear of poor evaluations, hierarchy/powerlessness, a “don’t speak up” culture, the desire to be a team player, limited clinical experience, and perceiving doctors as “good people” who provide disparate care unintentionally. Impact on professional development varied, ranging from students’ normalization of disparities as stemming from clinical constraints to increased motivation to provide equitable care.

Conclusions

Medical students routinely witness health care disparities during clerkships, and their observations spotlight specific clinical practices. For some students, these observations lead to a normalization of disparities; for others, they heighten commitment to equity. Clinical curricula should incorporate responding to health care disparities.
Expert Consensus on Inclusion of the Social Determinants of Health in Undergraduate Medical Education Curricula
Authors: Mangold Karen A. , Bartell Tami R. , Doobay-Persaud Ashti A. , Adler Mark D. , Sheehan Karen M.
Published: January 2019

Purpose

Accreditation bodies have mandated teaching social determinants of health (SDH) to medical students, but there has been limited guidance for educators on what or how to teach, and how to evaluate students’ competence. To fill this gap, this study aimed to develop an SDH curricular consensus guide for teaching SDH to medical students.

Method

In 2017, the authors used a modified Delphi technique to survey an expert panel of educators, researchers, students, and community advocates about knowledge, skills, and attitudes (KSA) and logistics regarding SDH teaching and assessment. They identified the panel and ranked a comprehensive list of topics based on a scoping review of SDH education studies and discussions with key informants. A total of 57 experts were invited.

Results

Twenty-two and 12 panelists participated in Delphi rounds 1 and 2, respectively. The highest-ranked items regarding KSA were “Appreciation that the SDH are some of the root causes of health outcomes and health inequities” and “How to work effectively with community health workers.” The panel achieved consensus that SDH should constitute 29% of the total curriculum and be taught continuously throughout the curriculum. Multiple-choice tests were ranked lowest as an assessment method, and patient feedback was ranked highest. Panelists noted that SDH content must be a part of standardized exams to be prioritized by faculty and students.

Conclusions

An expert panel endorsed essential curricular content, teaching methods, and evaluation approaches that can be used to help guide medical educators regarding SDH curriculum development.
A Conversation About the Role of Humiliation in Teaching: The Ugly, the Bad, and the Good
Authors: Hoskison Karl , Beasley Brent W.
Published: January 2019

In this Invited Commentary, the authors identify the ugly, the bad, and the good in teaching in medical education, based on their experiences as medical students and then educators. They reflect on the mistreatment they endured during medical school and its impact on their education and their careers as educators. They also highlight those exemplars from their training who role modeled the type of physician and educator they want to be. The authors conclude by describing the elements of learner-centered education that they practice, which may be helpful for others to consider, and call on their fellow educators to end the practice of humiliating learners by moving away from a controlled-motivation model toward an autonomy-supportive approach to education.