bluuebunny/crossref_metadata_2025 huggingface dataset:
Sediment properties in the fluvial and estuarine environments of the Mekong River
Authors: Le Hoang-Anh , Gratiot Nicolas , Santini William , Ribolzi Olivier , Soares-Frazao Sandra , Deleersnijder Eric
Published: September 2018

The Mekong river, located in Southeast Asia, is one of the largest rivers in the world. It is facing serious problems related to sediment transport, e.g. the reduction of sediment volume supply to the delta and estuary. This study focuses on the physical properties of suspended particles in the upstream fluvial section (Luang Prabang, Laos) and in the region of tidal influence (Song Hau estuary, Vietnam). These sites are respectively the upper and lower limits of the Lower Mekong River (LMR), which are experiencing contrasted transport modes. The main objective of this study is to quantify the proportion of inert sand and of cohesive particles in the water through comprehensive measurements of particle size, settling velocity and flocculation in the water column. Two field campaigns were undertaken in the summer monsoon season. The results point out the predominance of flocculi, with sizes of 18 ± 5 μm in the fluvial environment and 15 ± 5 μm in the estuary and the similarities in patterns, mixture of sand (12 ± 5 %) and mud (88 ± 5 %). They also provide a statistically representative set of suspended particle populations in the upstream and downstream regions that could be used for improving numerical models.
Bed Load Transport Modelling Using Kinetic Theory
Authors: Matoušek Václav , Zrostlík Štěpán
Published: September 2018

Intense transport of bed load is associated with highconcentrated sediment-laden flow over a plane mobile bed at high bed shear. Typically, the flow exhibits a layered internal structure in which a vast majority of sediment grains is transported through a collisional layer above the bed. Our investigation focuses on steady uniform open-channel flow with a developed collisional transport layer and combines modelling and experiment to relate integral quantities, as the discharge of solids, discharge of mixture, and flow depth with the longitudinal slope of the bed and the internal structure of the flow above the bed. In the paper, flow with the internal structure described by linear vertical distributions of granular velocity and concentration across the collisional layer is analyzed by a model based on the classical kinetic theory of granular flows. The model predicts the total discharge, the discharge of sediment, and the flow depth for given (experimentally determined) bed slope and thickness of collisional layer. The model also predicts whether the intefacial dense layer develops between the bed and the collisional layer and how thick it is. Model predictions are compared with results of intense bed-load experiment carried out for lightweight sediment in our laboratory tilting flume.
MEASUREMENT OF INUNDATING FLOW FROM A BROKEN ENBANKMENT BY USING VIDEO IMAGES SHOOT FROM A MEDIA HELICOPTER
Authors: Fujita Ichiro , Notoya Yuichi , Furuta Takanori
Published: September 2018

The heavy rain disaster in the Kinugawa River basin that occurred along with the passage of the Typhoon 18 caused the embankment destruction in the middle reach of the river on September 10, 2015. Due to the overflow, the houses in the vicinity of the embankment collapsed, causing a flood inundation spreading over a wide area. Because the embankment breakwater occurred during the daytime, the state of the inundating flow was recorded from various angles by media helicopters or drones. In this study, we developed a method to extract quantitative flow information from a helicopter video image in which the shooting position and angles are changed one after another, because it was taken in emergency. In the analysis, the images were orthorectified after stabilizing the images, from which surface velocity distributions were measured by image-based technique such as the large-scale particle image velocimetry (LSPIV) or the space-time image velocimetry (STIV). As a result, the time change of water entering from the broken embankment and the total inundated water volume during the disaster were estimated. In addition, two-dimensional surface velocity distributions were analysed to show the spreading of inundated flow.
Wavenumber-frequency analysis of river surface texture to improve accuracy of image-based velocimetry
Authors: Tani Kojiro , Fujita Ichiro
Published: September 2018

In the unseeded image-based techniques for river surface flow measurements, advection speed of surface textures composed of surface ripples or floating objects is measured by image analysis. However, the methods would yield erroneous information when the surface texture is affected by gravity waves propagating in all directions. In order to improve the measurement accuracy, such wave effects have to be subtracted in the image analysis. For that purpose, a wavenumber-frequency analysis was applied to a space-time image (STI) generated in the space-time image velocimetry (STIV) analysis and succeeded in eliminating the wavegenerated pattern contained in the texture in STI. It was made clear that turbulence-generated texture propagates at the speed of surface flow.
The German National Flood Protection Programme: Evaluating the impact of supraregional flood protection measures on extreme floods using hydrodynamic modelling
Authors: Schuh Carina , Hatz Marcus
Published: September 2018

After the disastrous flood events of June 2013 in the German Elbe and Danube catchments, the German government together with the federal states decided on the joint elaboration of a nationwide flood protection programme (NHWSP, 2015-2027+). Within the frame of this programme, the government supports the realization of large-scale retention measures for the improvement of supra-regional flood prevention. For scientific monitoring, the Federal Institute of Hydrology (BfG) was mandated to conduct a two-part preparatory ad hoc study (2014-2015) and a subsequent research project (2015-2019) evaluating the collective impact of the planned retention measures on flooding processes and flood peak reduction in the Danube, Elbe, and Rhine basins. Findings from the ad hoc study provided the government with first elements of evidence for taking its decision on the elaboration of the NHWSP programme, and supported the development of a modelling strategy for the accompanying research project. By using extensive sets of hydrodynamic models, the research project takes into account the complex interrelations between supra-regional flood formation, flooding process, and retention control concepts when evaluating flood reduction on catchment level. It is expected to technically substantiate the government's NHWSP programme by refining the criteria for identification and prioritization of measures.
Influence of floodplain and riparian vegetation in the conveyance and structure of turbulent flow in compound channels
Authors: Fernandes João N. , Leal João B. , Cardoso António H.
Published: September 2018

The present study aims at understanding the changes in the channel conveyance and in the turbulent flow structure due to the presence of both submerged vegetation in the floodplains and riparian vegetation. An experimental campaign was carried out comprising uniform compound channels flows (i) without any kind of vegetation, (ii) with synthetic grass in the floodplains, (iii) with synthetic grass in the floodplains and rods in the interface between main channel and the floodplain and (iv) with synthetic grass in the floodplains and artificial shrubs in the interface between main channel and the floodplain. For comparison, the water depth in all flow cases was kept constant. Accurate acoustic Doppler velocimetry was used to evaluate the 3d velocity field and the turbulence structures characteristics.
A comparative analysis of 3-D representations of urban flood map in virtual environments for hazard communication purposes
Authors: De Santis Rosa , Macchione Francesco , Costabile Pierfranco , Costanzo Carmelina
Published: September 2018

The flood hazard/risk maps do not allow a non-expert audience an immediate perception of the flooding impacts. Therefore, we need to modernize maps providing new communication approaches. In this context, 3-D representations of flood inundation through emerging formats in virtual and augmented realities may be considered as a powerful tool to engage users with flood hazards. The challenge of the research is to create a virtual 3-D environment aimed at supporting the public, practitioners and decision-makers in interpreting and understanding the impact of simulated flood hazards. For this purpose, the paper aims to perform a comparative analysis of two techniques to carry out the 3-D realistic visualizations of a flood map for representing a potential flooding of the Crati River, in the old town of Cosenza (South of Italy). The first approach develops a simple and quick workflow that provides an overall look at a neighbourhood level, but reveals some limits in water level visualization at the individual buildings scale. The second one requires additional terrestrial laser scanning (TLS) acquisition and overcomes some limits of the first approach, by providing a visual insight about water level close to building façades.
Estimation of Critical Uncertainty Sources in Discharge Measurements using Controlled Experimental Conditions
Authors: Kim Dongsu , Despax Aurélien , Muste Marian , Le Coz Jérôme
Published: September 2018

Providing experimental results along with associated uncertainties is essential not only for ensuring confidence in the quality of the final results but also for guiding improved instrument design and the protocols for measurement acquisition. Moreover, if the uncertainty analysis is conducted in a controlled manner and over a wide range for the measured variables its results can serve as a decision-making aid in conducting new experiments. This paper provides three examples of end-to-end assessments of the impact of uncertainty sources involved in the discharge estimation in open channels using point velocities measured with Acoustic Doppler Velocimeter. The analyzed uncertainty sources are: a) the sampling duration for velocity measurement, b) the number of points in the verticals, and, c) the number of verticals across the measurement cross-section. The raw data for the uncertainty estimations were acquired at the KICT River Experiment Center (South Korea), an experimental facility designed for facilitiating quasi natural-scale experiments. The three sources of uncertainties are assembled in practical visualization means that can be used for planning the acquisition of new experiments with similar instruments.
Heat transfer convection of a power law fluid flow within a parallel plate channel provided with two generating obstacles
Authors: Boudiaf Ahlem , Danane Fetta , Benkahla Youb Khaled , Labsi Nabila , Boutra Abdelkader
Published: September 2018

The main objective of this work is to examine the heat transfer changes induced by the presence of heat generating obstacles and that for non-Newtonian fluid flow within a parallel plate channel. The effects of the two obstacle height and the distance between them, on the flow structure and Nusselt number are examined. The Finite Volume Method is used to discretize the conservation equations of mass, momentum, and energy. The SIMPLER algorithm is applied to remove the checkerboard pressure problem. The results are discussed in terms of streamlines and the Nusselt number for three combinations of height and separation distance of the two obstacles. Two recirculation zones are observed for all the cases with different intensity varying with the size of the obstacle and the separation distance. Likewise the results show that the heat removal, occurring by the Nusselt number variations, is widely affected by the size of the obstacles as well as by the distance between them.
Numerical simulation of heat transfer during leaf spring industrial quenching process
Authors: Slama Salma , Bouhafs Mahmoud , Bessrour Jamel , Ben Jaber Moez , Mokdadi Hassan
Published: September 2018

This study is carried out in partnership with the company CAVEO, manufacturer of leaf springs for vehicles. It concerns the development of a numerical model intended to follow the space-time temperature evolution of a leaf during two processing operations: hot cambering and quenching. This leaf is of a parabolic profile, made of EN-51CrV4 steel (AISI-6150). After austenitization, it passes through a cambering operation to confer it the desired deflection and then a quenching operation. This quenching is carried out in an oil bath to achieve better mechanical properties. The prediction of the temperature during quenching involves determining the heat transfer coefficient between the leaf and the oil bath. This coefficient is determined by quenching, under the same conditions as the leaf, using a standard probe of the same steel. The numerical model is based on the resolution of the transient heat equation by considering the heat loss flows towards the heterogeneous environment (ambient air, press contact and quenching oil). The results obtained by this model give the space-time temperature evolution of the leaf from the exit of the heating furnace to the exit of the oil bath. The numerical results are compared to the experimental profiles obtained through thermographic images throughout cambering and quenching operations. These results are consistent with experimental results.
Penetration/Aspiration bei gesunden Erwachsenen: ein
unterschätztes Phänomen?
Authors: Schwemmle Cornelia
Published: September 2018

Butler SG et al. Aspiration as a Function of Age, Sex, Liquid Type, Bolus Volume,
and Bolus Delivery Across the Healthy Adult Life Span. Ann Otol Rhinol Laryngol
2018; 127: 21–32

Mittels funktioneller endoskopischer Schluck-Untersuchung (FEES) wurden
Faktoren bestimmt, die im Verlauf des Erwachsenenlebens das Eindringen und
die Aspiration während des Schluckens beeinflussen. Die amerikanischen
HNO-Ärzt/innen vermuteten, dass bei gesunden Älteren ein höherer Fettgehalt
in Flüssigkeiten, das Bolusvolumen, die Aufnahme mit einem Strohhalm,
fortgeschrittenes Alter und männliches Geschlecht das Aspirationsrisiko
erhöht.
Psychische Auswirkungen der Frühgeburt auf die Eltern
Authors: Weigl Tobias
Published: September 2018

Die Frühgeburt ihres Kindes erleben Eltern meist als ein belastendes Ereignis. In seiner Doktorarbeit ging der Autor der Frage nach, welche psychischen Auswirkungen dies auf die Mütter und Väter hat. In diesem Artikel schildert er, wie sich die aktuelle Versorgungssituation darstellt und welche Empfehlungen sich daraus für den Umgang der Hebamme mit betroffenen Eltern ergeben.
Palliative Chirurgie beim metastasierten Urothelkarzinom
Authors: Hübner Nicolai , Shariat Shahrokh
Published: September 2018

Palliative Chirurgie wird zur Linderung von Symptomen und auch zur Verbesserung des Überlebens bei einigen Tumorentitäten eingesetzt. Beim Urothelkarzinom ist die Rolle der palliativen Chirurgie ist gering und klinische Daten sind selten. Durch besseres Ansprechen auf systemische Therapien werden aber auch zunehmend chirurgische Interventionen im Rahmen von individuellen Behandlungskonzepten durchgeführt und anschließend als Fallserien publiziert. Bei niedriger Metastasenlast, bzw. bei Tumoren, die sich auf Lymphknoten, in- und außerhalb des Beckens, bzw. singuläre Metastasen in der Lunge beschränken, scheinen einige ausgewählte Patienten auch davon zu profitieren. Das Abschätzen von Nutzen und Risiko ist allerdings schwierig und muss für jeden Patienten neu überlegt werden, weshalb prospektive Studien vermutlich auch in Zukunft nicht existieren werden. Diese Übersichtsarbeit versucht, die wichtigsten Publikationen zu diesem Thema zusammenzufassen.
Polydopamine: An Emerging Material in the Catalysis of Organic Transformations
Authors: Kunfi Attila , London Gábor
Published: September 2018

Polydopamine, a ‘mussel-inspired’ polymer, has been explored extensively in materials science as a universal coating. However, as an easily available, stable and environmentally benign material, it has recently been discovered to demonstrate catalytic applications. In this short review, we briefly discuss the main approaches employing polydopamine in the catalysis of organic transformations. These include metal/polydopamine-type systems and metal-free approaches that exploit the acid/base properties of this versatile polymer.

1 Introduction

2 PDA and Metal Catalysis

2.1 Reduction of Nitroaryl Compounds to Anilines

2.2 Reduction of Carbonyl Compounds to Alcohols

2.3 Suzuki and Heck Coupling Reactions

2.4 Other Reactions Catalyzed by M/PDA-Type Systems

3 PDA as a Catalyst Itself

4 Conclusion
Role of structural distortion on thermoelectric aspects of heavily Sr2+ doped GdMnO3
Authors: Tanwar Khagesh , Anjum Farheen , Shukla Ashutosh K. , Maiti Tanmoy
Published: September 2018

Manganites had been proposed as one of the potential n-type oxide materials to develop thermoelectric power generators. In the present investigation, we studied the structural and thermoelectric properties of Gd1-xSrxMnO3 (GSMO) (0.5 ≤ x ≤ 0.8) polycrystalline ceramics synthesized by a conventional solid-state route. Rietveld refinement of XRD patterns revealed the distorted orthorhombic Pbnm crystal structure in all the compositions. The decrease in J-T distortions, present on the Gd-rich side of GSMO (x ≤ 0.6), due to favored formation of Mn4+ was calculated. Thermoelectric properties such as Seebeck coefficient (S) and electrical conductivity (σ) of these ceramics were measured in the temperature range from room temperature to 900 °C. The negative values of the Seebeck coefficient throughout the temperature range confirm the n-type semiconducting nature in all the compositions. The conduction mechanism (below metal-semiconductor transition) of these materials was analyzed using the small polaron hopping conduction model.
Note: Optical filter method for high-resolution magnetostriction measurement using fiber Bragg grating under millisecond-pulsed high magnetic fields at cryogenic temperatures
Authors: Ikeda Akihiko , Matsuda Yasuhiro H. , Tsuda Hiroshi
Published: September 2018

High-resolution magnetostriction measurement of ΔL/L ∼ 10−6 at a speed of 5 MHz is performed using the optical filter method as the detection scheme for the fiber Bragg grating (FBG) based strain monitor under 35-ms pulsed high magnetic fields up to 45 T at 2.2 K. The resolution of magnetostriction is about the same order as the conventionally reported value from FBG based magnetostriction measurement systems for millisecond pulsed magnetic fields. The measurement speed is ∼100 times the conventional ones. The present system can be a faster alternative for the conventional FBG based magnetostriction measurement system for millisecond pulsed high magnetic fields.
Accurate numerical modeling of residual stress fields induced by laser shock peening
Authors: Sun Boyu , Qiao Hongchao , Zhao Jibin
Published: September 2018

To improve the accuracy of numerical simulation of laser shock peening, a novel model is developed to predict residual stress distribution. An optical beam measurement system, a white light confocal displacement sensor, and other sensors are used to measure the laser shock peening parameters. Based on actual parameters, the model of shock wave pressure spatial distribution is established. Effects of key parameters, viz., overlapping rate and laser beam quality on residual stress distribution are analyzed by the proposed model. The influence mechanism of laser beam quality on residual stress hole is analyzed. Compared with conventional models, it is found that the proposed model has higher precision to predict residual stress distribution. The processing efficiency and strengthening effect can be improved by optimizing the overlapping rate and laser beam quality. The edge gradient of shock wave pressure reduces the intensity of the release wave convergence at the center, which can improve the uniformity of residual stress distribution. The proposed model can not only improve the accuracy of numerical simulation, but also provide guidance for optimizing the laser beam quality.
Theory of critical balance in plasma turbulence
Authors: Terry P. W.
Published: September 2018

Critical balance, a statement of the approximate equality of a timescale of motion parallel to the magnetic field with a timescale of turbulent motion perpendicular to the field, is analyzed from a statistical description of the relative motion of two particles consistent with two-point correlation in a nonlinear gyrokinetic system with collisions. Critical balance is understood from a premise that the fastest time to any spatial scale that encounters decorrelated motions sets an overall correlation time for both perpendicular and parallel scales. For a regime of weak collisionality, this leads to the approximate equality of the parallel streaming time and the perpendicular turbulent correlation time, which is a standard statement of critical balance. These two timescales are only approximately equal because of effects in parallel streaming dynamics and collisions, the former producing deviations tied to variations of perpendicular and parallel wavenumbers. Analysis of a collisional regime shows that critical balance also applies in that limit with a modified relation between parallel and perpendicular spatial scales.
Enhancing concentrator monocrystalline Si solar cells by down conversion Ce3+-Yb3+ co-doped YAG phosphors
Authors: Li Lu , Lou Chaogang , Cao Huihui , Diao Han , Karunakaran Santhosh Kumar
Published: September 2018

Down conversion Ce3+-Yb3+ co-doped YAG phosphors are used to enhance concentrator monocrystalline silicon solar cells. The coating of polymethyl methacrylate (PMMA) mixed with the phosphors is deposited on the surface of the solar cells by spin-coating method. It is found that the solar cells with the phosphor coating always have higher conversion efficiency than the bare solar cells under different illumination intensities. This is attributed to the down conversion effect of the phosphors and the reduced reflection (especially in the wavelength range 350–550 nm). The reflection of the light emitted from the phosphor's particles at the air/PMMA interface also contributes to the improvement. The relative growth in the conversion efficiency of the solar cells with the phosphor coatings increases with the illumination intensity from 4.86% under 100 mW cm−2 to 6.04% under 400 mW cm−2 because the increase in the emission from the phosphors is faster than that of the illumination intensity when the illumination intensity increases.
Steep switching in trimmed-gate tunnel FET
Authors: Asai Hidehiro , Mori Takahiro , Matsukawa Takashi , Hattori Junichi , Endo Kazuhiko , Fukuda Koichi
Published: September 2018

We propose a tunnel field-effect transistor (TFET) having a trimmed gate (TG) structure, which considerably improves the subthreshold swing (SS). The TG structure truncates the needless long band-to-band tunneling (BTBT) paths to a “channel”, which normally appear in a conventional TFET, and realize a sudden switching to the on-state arising from a short BTBT path. Our simulations demonstrate that the TG-TFET can achieve an extremely steep SS, less than 10 mV/decade, in the double-gated Si-channel configuration. The TG structure also improves the ratio ION/IOFF to a value higher than that of ideal MOSFETs in the operation voltage range up to 0.35 V. The mechanism of steep switching is based on a simple modification of the gate electrostatic control; therefore, in addition to the demonstrated TFETs, the TG structure is universally applicable to many types of TFETs.
Surface reaction kinetics in atomic layer deposition: An analytical model and experiments
Authors: Muneshwar Triratna , Cadien Ken
Published: September 2018

Atomic layer deposition (ALD) surface reactions are comprised of several elementary surface interactions (such as physisorption, desorption, and chemisorption) occurring at the substrate. Since ALD processes are often far from thermodynamic equilibrium, the surface saturation behavior is controlled by the kinetics of these involved interactions. In this article, we present a first-order kinetic model for ALD reaction, to simulate the cumulative effect of precursor exposure (tA), post-precursor purge (tP1), reactant exposure (tB), post-reactant purge (tP2), and substrate temperature (Tsub) on the resulting growth per cycle (GPC) in an ABAB… pulsed ALD process. Furthermore, to simulate the effect of inadequate reactor purges (tP1, and/or tP2) and undesired non-ALD side reactions, reaction pathways to account excess GPC are also taken into consideration. From our model calculations, we simulate GPC vs Tsub trends observed in ALD growth experiments and demonstrate that the process temperature window (ΔTALD) for a constant GPC depends upon the deposition cycle parameters tA, tP1, tB, and tP2. The modeled GPC vs Tsub trends are discussed and compared with SiNx, ZrN, and ZnO PEALD growth experiments.
Large tunnel magnetoresistance and temperature-driven spin filtering effect based on the compensated ferrimagnetic spin gapless semiconductor Ti2MnAl
Authors: Han Jiangchao , Gao Guoying
Published: September 2018

Spin gapless semiconductors, also known a special class of half-metallic magnets, have received more and more attention in spintronic applications due to the complete spin polarization and the electrical conductivity between half-metals and semiconductors. Motivated by the recent synthesis of spin gapless semiconductor Ti2MnAl with compensated ferrimagnetism (zero net magnetic moment) and high Curie temperature (above 650 K), we investigate the bias-voltage- and temperature-driven spin transport properties based on Ti2MnAl by using the density functional theory combined with nonequilibrium Green’s function method. A large tunnel magnetoresistance ratio (up to 2.8 × 106%), spin Seebeck effect, and temperature-driven spin filtering effect are found in the Ti2MnAl/InAs/Ti2MnAl(001) magnetic tunnel junction. These versatile transport properties suggest the potential applications for Ti2MnAl in spintronic devices and spin caloritronic devices.
Efficient longitudinal relaxation time measurement of 129Xe via bias-approach
Authors: Xiang Zhan , Qiyuan Jiang , Zhiguo Wang , Hui Luo , Hongchang Zhao
Published: September 2018

We proposed a new bias-approach method for measuring longitudinal relaxation time of 129Xe. Compared with the delayed pulse method, the measuring time of the proposed single-scan bias-approach is significantly decreased by more than 20 times, and the differences are 2% and 0.7% of two sample cell A and B respectively. By giving a small static magnetic field in the transverse domain, a π-pulse-induced 87Rb magnetometer signal bias with respect to the longitudinal magnetization of xenon was obtained. We then use a π/2 pulse to find the half-life time of longitudinal relaxation. Since the bias-approach has a low requirement of the systematic robust, it naturally becomes a more efficient method to measure the longitudinal relaxation time with respect to the noble gas in the vapor cell.
Altered ER–mitochondria contact impacts mitochondria calcium homeostasis and contributes to neurodegeneration in vivo in disease models
Authors: Lee Kyu-Sun , Huh Sungun , Lee Seongsoo , Wu Zhihao , Kim Ae-Kyeong , Kang Ha-Young , Lu Bingwei
Published: September 2018

Significance

Ca
2
+
regulates cellular metabolism, proliferation, and differentiation. Ca
2+
homeostasis is critical for cellular function and health. Mitochondria help buffer transient Ca
2+
elevations and prevent cell death induced by Ca
2+
overload. Mito-Ca
2+
is also required for optimal activity of certain key mitochondrial functions, such as oxidative phosphorylation and metabolism. Thus, mito-Ca
2+
homeostasis assumes central roles in cellular health. Endoplasmic reticulum (ER) and mitochondria make intimate contacts and exchange molecules such as Ca
2+
and lipids. We find that ER-to-mitochondria Ca
2+
transfer is important for mito-Ca
2+
homeostasis and that the conserved Miro protein is critically involved. We show that mito-Ca
2+
homeostasis is disrupted in neurodegenerative disease models and its restoration is beneficial. Our findings have important implications for therapeutic intervention of neurodegenerative diseases.
Structure of the membrane proximal external region of HIV-1 envelope glycoprotein
Authors: Fu Qingshan , Shaik Md Munan , Cai Yongfei , Ghantous Fadi , Piai Alessandro , Peng Hanqin , Rits-Volloch Sophia , Liu Zhijun , Harrison Stephen C. , Seaman Michael S. , Chen Bing , Chou James J.
Published: September 2018

The membrane-proximal external region (MPER) of the HIV-1 envelope glycoprotein (Env) bears epitopes of broadly neutralizing antibodies (bnAbs) from infected individuals; it is thus a potential vaccine target. We report an NMR structure of the MPER and its adjacent transmembrane domain in bicelles that mimic a lipid-bilayer membrane. The MPER lies largely outside the lipid bilayer. It folds into a threefold cluster, stabilized mainly by conserved hydrophobic residues and potentially by interaction with phospholipid headgroups. Antigenic analysis and comparison with published images from electron cryotomography of HIV-1 Env on the virion surface suggest that the structure may represent a prefusion conformation of the MPER, distinct from the fusion-intermediate state targeted by several well-studied bnAbs. Very slow bnAb binding indicates that infrequent fluctuations of the MPER structure give these antibodies occasional access to alternative conformations of MPER epitopes. Mutations in the MPER not only impede membrane fusion but also influence presentation of bnAb epitopes in other regions. These results suggest strategies for developing MPER-based vaccine candidates.
Evaluation of tropical coastal land cover and land use changes and their impacts on ecosystem service values
Authors: Ligate Elly Josephat , Chen Can , Wu Chengzhen
Published: September 2018

Understanding about land cover and land use (LCLU) changes, as well as the associated impacts on ecosystem service values (ESV) is extremely important in the management of coastal ecosystems globally. Thus, this study assessed temporal LCLU changes, the underlying socioeconomic drivers and dynamics of ESV in the coastal zone of Tanzania. The LCLU data for 2000 and 2010 were from the Globe Land 30 mapping products at 30-meter spatial resolution developed by National Geomatics Center of China, while 2016 images were produced from Landsat 8. Classification of images was done from Landsat TM/ETM+ for 2000, 2010, and 2016 years complemented with MODIS and Normalized Difference Vegetation Index time series, and Chinese HJ imagery. LCLU categories and ecosystem service coefficients were used to compute ESV on each LCLU categories. Between 2000 and 2016, farmland, shrub land, waterbody, and artificial surface expanded while forest, grazing land, and wetlands declined. The ESV increased on farmland, shrub land, and waterbody, while the decline was found on forest, grazing land, and wetlands. The ESV and the total population ratios declined from $80.4, 63.8, and $46.0 million in 2000, 2010, and 2016, respectively. Perfect positive correlation was on LCLU change and ESV, population and households in crop farming, livestock keeping, and bioenergy use. Population pressure and socioeconomic activities have amplified the degradation of the coastal ecosystems. If not abetted, there is a danger of further impairments on these ecosystems. We advise to regulate population and socioeconomic activities to avoid more negative impacts of coastal LCLU change.
The Population-Level Impacts of Excluding Norovirus-Infected Food Workers From the Workplace: A Mathematical Modeling Study
Authors: Yang Wen , Steele Molly , Lopman Ben , Leon Juan S , Hall Aron J
Published: September 2018

Norovirus is the leading cause of acute gastroenteritis and foodborne disease in the United States. The Food and Drug Administration recommends that food workers infected with norovirus be excluded from the workplace while symptomatic and for 48 hours after their symptoms subside. Compliance with this recommendation is not ideal, and the population-level impacts of changes in food-worker compliance have yet to be quantified. We aimed to assess the population impacts of varying degrees of compliance with the current recommendation through the use of a compartmental model. We modeled the number and proportion of symptomatic norovirus cases averted annually in the US population (using data from 1983–2014) in specific age groups (children aged <5 years, children aged 5–17 years, adults aged 18–64 years, and adults aged ≥65 years) under various scenarios of food-worker exclusion (i.e., proportion compliant and days of postsymptomatic exclusion) in comparison with a referent scenario which assumed that 66.6¯% of norovirus-symptomatic food workers and 0% of postsymptomatic food workers were excluded from work. Overall, we estimated that 6.0 million cases of norovirus have already been avoided annually under the referent scenario and that 6.7 million (28%) more cases might be avoided through 100% compliance with the current recommendations. Substantial population-level benefits were predicted from improved compliance in exclusion of norovirus-infected food workers from the workplace—benefits that may be realized through policies or programs incentivizing self-exclusion.
Early-Emerging Sulcal Patterns Are Atypical in Fetuses with Congenital Heart Disease
Authors: Ortinau Cynthia M , Rollins Caitlin K , Gholipour Ali , Yun Hyuk Jin , Marshall Mackenzie , Gagoski Borjan , Afacan Onur , Friedman Kevin , Tworetzky Wayne , Warfield Simon K , Newburger Jane W , Inder Terrie E , Grant P Ellen , Im Kiho
Published: September 2018

Fetuses with congenital heart disease (CHD) have third trimester alterations in cortical development on brain magnetic resonance imaging (MRI). However, the intersulcal relationships contributing to global sulcal pattern remain unknown. This study applied a novel method for examining the geometric and topological relationships between sulci to fetal brain MRIs from 21–30 gestational weeks in CHD fetuses (n = 19) and typically developing (TD) fetuses (n = 17). Sulcal pattern similarity index (SI) to template fetal brain MRIs was determined for the position, area, and depth for corresponding sulcal basins and intersulcal relationships for each subject. CHD fetuses demonstrated altered global sulcal patterns in the left hemisphere compared with TD fetuses (TD [SI, mean ± SD]: 0.822 ± 0.023, CHD: 0.795 ± 0.030, P = 0.002). These differences were present in the earliest emerging sulci and were driven by differences in the position of corresponding sulcal basins (TD: 0.897 ± 0.024, CHD: 0.878 ± 0.019, P = 0.006) and intersulcal relationships (TD: 0.876 ± 0.031, CHD: 0.857 ± 0.018, P = 0.033). No differences in cortical gyrification index, mean curvature, or surface area were present. These data suggest our methods may be more sensitive than traditional measures for evaluating cortical developmental alterations early in gestation.
Early Adolescence is a Critical Period for the Maturation of Inhibitory Behavior
Authors: Reynolds Lauren M , Yetnikoff Leora , Pokinko Matthew , Wodzinski Michael , Epelbaum Julia G , Lambert Laura C , Cossette Marie-Pierre , Arvanitogiannis Andreas , Flores Cecilia
Published: September 2018

Psychiatric conditions marked by impairments in cognitive control often emerge during adolescence, when the prefrontal cortex (PFC) and its inputs undergo structural and functional maturation and are vulnerable to disruption by external events. It is not known, however, whether there exists a specific temporal window within the broad range of adolescence when the development of PFC circuitry and its related behaviors are sensitive to disruption. Here we show, in male mice, that repeated exposure to amphetamine during early adolescence leads to impaired behavioral inhibition, aberrant PFC dopamine connectivity, and reduced PFC dopamine function in adulthood. Remarkably, these deficits are not observed following exposure to the exact same amphetamine regimen at later times. These findings demonstrate that there is a critical period for the disruption of the adolescent maturation of cognitive control and PFC dopamine function and suggest that early adolescence is particularly relevant to the emergence of psychopathology in humans.
Derivation and validation of a prognostic model to predict mortality in patients with advanced chronic kidney disease
Authors: Schmidt Rebecca J , Landry Daniel L , Cohen Lewis , Moss Alvin H , Dalton Cheryl , Nathanson Brian H , Germain Michael J
Published: September 2018

Background

Guiding patients with advanced chronic kidney disease (CKD) through advance care planning about future treatment obliges an assessment of prognosis. A patient-specific integrated model to predict mortality could inform shared decision-making for patients with CKD.

Methods

Patients with Stages 4 and 5 CKD from Massachusetts (749) and West Virginia (437) were prospectively evaluated for clinical parameters, functional status [Karnofsky Performance Score (KPS)] and their provider’s response to the Surprise Question (SQ). A predictive model for 12-month mortality was derived with the Massachusetts cohort and then validated externally on the West Virginia cohort. Logistic regression was used to create the model, and the c-statistic and Hosmer–Lemeshow statistic were used to assess model discrimination and calibration, respectively.

Results

In the derivation cohort, the SQ, KPS and age were most predictive of 12-month mortality with odds ratios (ORs) [95% confidence interval (CI)] of 3.29 (1.87–5.78) for a ‘No’ response to the SQ, 2.09 (95% CI 1.19–3.66) for fair KPS and 1.41 (95% CI 1.15–1.74) per 10-year increase in age. The c-statistic for the 12-month mortality model for the derivation cohort was 0.80 (95% CI 0.75–0.84) and for the validation cohort was 0.74 (95% CI 0.66–0.83).

Conclusions

Our integrated prognostic model for 12-month mortality in patients with advanced CKD had good discrimination and calibration. This model provides prognostic information to aid nephrologists in identifying and counseling advanced CKD patients with poor prognosis who are facing the decision to initiate dialysis or pursue medical management without dialysis.
The course and predictors of perceived unsupportive responses by family and friends among women newly diagnosed with gynecological cancers
Authors: Manne Sharon L , Kashy Deborah A , Kissane David W , Ozga Melissa , Virtue Shannon Myers , Heckman Carolyn J
Published: September 2018

Perceived unsupportive responses from close others play an important role in psychological adaptation of patients with cancer. Little is known about whether these negative responses change after someone experiences a serious life event, and even less is known about the individual characteristics and related factors that might contribute to both the levels of and changes in perceived unsupportive responses over the course of adaptation to an experience. This longitudinal study aimed to evaluate changes in perceived unsupportive behavior from family and friends among women newly with gynecologic cancer as well as initial demographic, disease, and psychological factors that predict the course of perceived unsupportive behavior over time. Women (N = 125) assigned to the usual care arm of a randomized clinical trial comparing a coping and communication intervention with a supportive counseling intervention to usual care completed six surveys over an 18 month period. Growth models using multilevel modeling were used to predict unsupportive responses over time. Average levels of perceived unsupportive responses from family and friends were low. Unsupportive responses varied from patient to patient, but patients did not report a systematic change in perceived unsupportive responses over time. Cultivating meaning and peace and coping efficacy were associated with fewer perceived unsupportive responses as well as reductions in perceived unsupportive responses over time. Emotional distress, cancer concerns, functional impairment, holding back sharing concerns, and cognitive and behavioral avoidance predicted higher perceived unsupportive responses over time. The findings are discussed in terms of the self-presentation theory and social network responses to persons undergoing difficult life events.
Using the Clerkship Shelf Exam Score as a Qualification for an Overall Clerkship Grade of Honors: A Valid Practice or Unfair to Students?
Authors: Schilling David C.
Published: September 2018

Most clerkships require medical students to pass the National Board of Medical Examiners (NBME) subject (shelf) exam to pass the clerkship. Many use the NBME’s recommended honors cut score on the shelf exam to determine medical student eligibility for an overall clerkship grade of honors. This use of a conjunctive scoring model for determining honors is inconsistent with the logic behind the intended use of this model for making pass–fail determinations. Further, many clerkships use grading systems that employ both this conjunctive model for honors eligibility and a compensatory scoring model for determining the overall clerkship grade. For students who fall short of the shelf exam honors cut score, such a grading system effectively increases the weighting of shelf exam performance and decreases the clerkship’s transparency about the weighting of performance on other assessments toward the clerkship composite score and overall grade. It may also lead to contradictory grading results in which student B has a higher composite score than student A, yet student B receives a lower overall grade. The author illustrates how to calculate a weight for shelf exam performance that would be fairer to students and would help create a more transparent weighting scheme for the grading system. The author recommends that clerkships restructure their grading systems so that shelf exam honors-eligibility cut scores are not used as conjunctive criteria for determining overall clerkship grades of honors. A reexamination of the NBME’s practice of suggesting honors-eligibility cut scores for shelf exams is also recommended.
Do Admissions Multiple Mini-Interview and Traditional Interview Scores Predict Subsequent Academic Performance? A Study of Five California Medical Schools
Authors: Jerant Anthony , Henderson Mark C. , Griffin Erin , Hall Theodore R. , Kelly Carolyn J. , Peterson Ellena M. , Wofsy David , Tancredi Daniel J. , Sousa Francis J. , Franks Peter
Published: September 2018

Purpose

To compare the predictive validities of medical school admissions multiple mini-interviews (MMIs) and traditional interviews (TIs).

Method

This longitudinal observational study of 2011–2013 matriculants to five California public medical schools examined the associations of MMI scores (two schools) and TI scores (three schools) with subsequent academic performance. Regression models adjusted for sociodemographics and undergraduate academic metrics examined associations of standardized mean MMI and TI scores with United States Medical Licensing Examination Step 1 and Step 2 Clinical Knowledge (CK) scores and, for required clerkships, with mean National Board of Medical Examiners Clinical Science subject (shelf) exam score and number of honors grades.

Results

Of the 1,460 medical students, 746 (51.1%) interviewed at more than one study school; 579 (39.7%) completed at least one MMI and at least one TI. Neither interview type was associated with Step 1 scores. Higher MMI scores were associated with more clerkship honors grades (adjusted incidence rate ratio [AIRR] 1.28 more [95% CI 1.18, 1.39; P < .01] per SD increase) and higher shelf exam and Step 2 CK scores (adjusted mean 0.73 points higher [95% CI 0.28, 1.18; P < .01] and 1.25 points higher [95% CI 0.09, 2.41; P = .035], respectively, per SD increase). Higher TI scores were associated only with more honors grades (AIRR 1.11 more [95% CI 1.01, 1.20; P = .03] per SD increase).

Conclusions

MMI scores were more strongly associated with subsequent academic performance measures than were TI scores.
Reflectance Confocal Microscopy Can Help the Dermatopathologist in the Diagnosis of Challenging Skin Lesions
Authors: Kelsey Andrew , Grant-Kels Jane M. , Rabinovitz Harold , Oliviero Margaret , Scope Alon
Published: September 2018

Despite the successful assignment of Current Procedural Terminology codes, there are barriers to incorporating in vivo reflectance confocal microscopy (RCM) into daily practice. Importantly, the dermatopathologist can play a key role in interpreting RCM images and can use these images to correlate with histopathology. Herein, we describe, using a case series, how RCM can be incorporated into the dermatopothalogist's practice. We also summarize the criteria for RCM diagnosis of common neoplasms.
Reporting of Baseline Characteristics to Accompany Analysis by Instrumental Variables
Authors: MacKenzie Todd A. , O’Malley A. James , Bekelis Kimon
Published: September 2018

A property and criticism of instrumental variable (IV) estimators is that they estimate the exposure effect in the compliers, individuals whose exposure is influenced by the instrument. It is conceivable that the exposure effect is different in individuals whose exposure is not influenced by the instrument. For that reason, it is useful to know who the compliers are. We present methods for reporting averages and other statistics and comparing them between the compliers and noncompliers, which are applicable to scenarios in which the instrument and exposure are fixed in time and dichotomous. The methods are illustrated in a comparison of outcomes between teaching and nonteaching hospitals in patients undergoing brain or spinal surgery.
Protective Action of Diazoxide on Isoproterenol-Induced Hypertrophy Is Mediated by Reduction in MicroRNA-132 Expression
Authors: Narasimhan Gayathri , Carrillo Elba D. , Hernández Ascención , García María C. , Sánchez Jorge A.
Published: September 2018

Introduction and Methods:

The effects of diazoxide on cardiac hypertrophy and miR-132 expression were characterized in adult rats and in cardiomyocytes. Diazoxide effects on reactive oxygen species (ROS) production and on the cAMP-response element binding (CREB) transcription factor's abundance in cardiomyocytes were also analyzed. ROS measurements used a fluorescent dye. Western blot analysis and quantitative Reverse Transcription Polymerase Chain Reaction were used to measure phosphorylated form of CREB (pCREB) abundance and miR-132 expression, respectively.

Results:

Isoproterenol (ISO) induced cardiac hypertrophy, an effect that was mitigated by diazoxide. The rate of ROS production, CREB phosphorylation, and miR-132 expression increased after the addition of ISO. H2O2 increased pCREB abundance and miR-132 expression; upregulation of miR-132 was blocked by the specific inhibitor of CREB transcription, 666-15. Consistent with a role of ROS on miR-132 expression, diazoxide prevented the increase in ROS production, miR-132 expression, and pCREB abundance produced by ISO. Phosphorylation of CREB by ISO was prevented by U0126, an inhibitor of mitogen-activated protein kinase.

Conclusions:

Our data first demonstrate that diazoxide mitigates hypertrophy by preventing an increase in miR-132 expression. The mechanism likely involves less ROS production leading to less phosphorylation of CREB. Our data further show that ROS enhance miR-132 transcription, and that ISO effects are probably mediated by the mitogen-activated protein kinase pathway.