bluuebunny/crossref_metadata_2025 huggingface dataset:
GLP-1 at physiological concentrations recruits skeletal and cardiac muscle microvasculature in healthy humans
Authors: Subaran Sharmila C. , Sauder Matthew A. , Chai Weidong , Jahn Linda A. , Fowler Dale E. , Aylor Kevin W. , Basu Ananda , Liu Zhenqi
Published: February 2014

Muscle microvascular surface area determines substrate and hormonal exchanges between plasma and muscle interstitium. GLP-1 (glucagon-like peptide-1) regulates glucose-dependent insulin secretion and has numerous extrapancreatic effects, including a salutary vascular action. To examine whether GLP-1 recruits skeletal and cardiac muscle microvasculature in healthy humans, 26 overnight-fasted healthy adults received a systemic infusion of GLP-1 (1.2 pmol/kg of body mass per min) for 150 min. Skeletal and cardiac muscle MBV (microvascular blood volume), MFV (microvascular flow velocity) and MBF (microvascular blood flow) were determined at baseline and after 30 and 150 min. Brachial artery diameter and mean flow velocity were measured and total blood flow was calculated before and at the end of the GLP-1 infusion. GLP-1 infusion raised plasma GLP-1 concentrations to the postprandial levels and suppressed plasma glucagon concentrations with a transient increase in plasma insulin concentrations. Skeletal and cardiac muscle MBV and MBF increased significantly at both 30 and 150 min (P<0.05). MFV did not change in skeletal muscle, but decreased slightly in cardiac muscle. GLP-1 infusion significantly increased brachial artery diameter (P<0.005) and flow velocity (P=0.05) at 150 min, resulting in a significant increase in total brachial artery blood flow (P<0.005). We conclude that acute GLP-1 infusion significantly recruits skeletal and cardiac muscle microvasculature in addition to relaxing the conduit artery in healthy humans. This could contribute to increased tissue oxygen, nutrient and insulin delivery and exchange and therefore better prandial glycaemic control and tissue function in humans.
Wideband rectangular printed monopole antenna for circular polarisation
Authors: Fujimoto Takafumi , Jono Kozo
Published: February 2014

A wideband printed rectangular monopole antenna for circularly polarised wave is proposed. The radiation characteristics of the wideband circular polarisation are achieved by designing the antenna asymmetrically. With simulations, the relationships between the antenna's geometrical parameters and the antenna's characteristics (axial ratio of circularly polarised wave and return loss) are clarified. The operational principle for wideband circular polarisation is explained by the simulated electric current distributions. Moreover, the simulated axial ratio, return loss, radiation patterns and gain are compared with the measured results. The simulated and measured bandwidths (3 dB axial ratio with a 10 dB return loss) are ∼56.2% (1.78–3.17 GHz) and 51.4% (1.82–3.08 GHz), respectively.
Dilute rigid dumbbell suspensions in large-amplitude oscillatory shear flow: Shear stress response
Authors: Bird R. B. , Giacomin A. J. , Schmalzer A. M. , Aumnate C.
Published: February 2014

We examine the simplest relevant molecular model for large-amplitude shear (LAOS) flow of a polymeric liquid: the suspension of rigid dumbbells in a Newtonian solvent. We find explicit analytical expressions for the shear rate amplitude and frequency dependences of the first and third harmonics of the alternating shear stress response. We include a detailed comparison of these predictions with the corresponding results for the simplest relevant continuum model: the corotational Maxwell model. We find that the responses of both models are qualitatively similar. The rigid dumbbell model relies entirely on the dumbbell orientation to explain the viscoelastic response of the polymeric liquid, including the higher harmonics in large-amplitude oscillatory shear flow. Our analysis employs the general method of Bird and Armstrong [“Time-dependent flows of dilute solutions of rodlike macromolecules,” J. Chem. Phys. 56, 3680 (1972)] for analyzing the behavior of the rigid dumbbell model in any unsteady shear flow. We derive the first three terms of the deviation of the orientational distribution function from the equilibrium state. Then, after getting the “paren functions,” we use these for evaluating the shear stress for LAOS flow. We find the shapes of the shear stress versus shear rate loops predicted to be reasonable.
Upgraded high time-resolved x-ray imaging crystal spectroscopy system for J-TEXT ohmic plasmas
Authors: Jin W. , Chen Z. Y. , Huang D. W. , Li Q. L. , Yan W. , Luo Y. H. , Lee S. G. , Shi Y. J. , Huang Y. H. , Tong R. H. , Yang Z. J. , Rao B. , Ding Y. H. , Zhuang G.
Published: February 2014

This paper presents the upgraded x-ray imaging crystal spectrometer (XICS) system on Joint Texas Experimental Tokamak (J-TEXT) tokamak and the latest experimental results obtained in last campaign. With 500 Hz frame rate of the new Pilatus detector and 5 cm × 10 cm spherically bent crystal, the XICS system can provide core electron temperature (Te), core ion temperature (Ti), and plasma toroidal rotation (VΦ) with a maximum temporal resolution of 2 ms for J-TEXT pure ohmic plasmas. These parameters with high temporal resolution are very useful in tokamak plasma research, especially for rapidly changed physical processes. The experimental results from the upgraded XICS system are presented.
Note: Folded optical system for narrow forward looking probe
Authors: Hou Hsuan-Chao , Hah Dooyoung , Kim Jeonghwan , Feldman M.
Published: February 2014

An optical system is described in which a laser beam makes three passes through a single graded index lens, forming a focus along the optic axis. It has important applications in endoscopic probes, where the forward looking characteristic permits the avoidance of obstacles and the narrow structure makes it minimally invasive.
Nanoconfined water under electric field at constant chemical potential undergoes electrostriction
Authors: Vanzo Davide , Bratko D. , Luzar Alenka
Published: February 2014

Electric control of nanopore permeation by water and solutions enables gating in membrane ion channels and can be exploited for transient surface tuning of rugged substrates, to regulate capillary permeability in nanofluidics, and to facilitate energy absorption in porous hydrophobic media. Studies of capillary effects, enhanced by miniaturization, present experimental challenges in the nanoscale regime thus making molecular simulations an important complement to direct measurement. In a molecular dynamics (MD) simulation, exchange of water between the pores and environment requires modeling of coexisting confined and bulk phases, with confined water under the field maintaining equilibrium with the unperturbed environment. In the present article, we discuss viable methodologies for MD sampling in the above class of systems, subject to size-constraints and uncertainties of the barostat function under confinement and nonuniform-field effects. Smooth electric field variation is shown to avoid the inconsistencies of MD integration under abruptly varied field and related ambiguities of conventional barostatting in a strongly nonuniform interfacial system. When using a proper representation of the field at the border region of the confined water, we demonstrate a consistent increase in electrostriction as a function of the field strength inside the pore open to a field-free aqueous environment.
Electron-paramagnetic resonance detection with software time locking
Authors: Aloisi Giovanni , Mannini Matteo , Caneschi Andrea , Dolci David , Carlà Marcello
Published: February 2014

A setup for electron paramagnetic resonance with narrow band digital detection is described. A low frequency reference tone is added to the radio frequency signal. This reference signal, after digital detection, is used to lock the resonance signal, even in the absence of hardware time locking among the radio frequency generator, the conversion local oscillators, and the sampling stage. Results obtained with 2,2-Diphenyl-1-Pycryl-Hydrazil are presented and discussed.
Wavy ferromagnetic device as single cell detection
Authors: Huang Hao-Ting , Ger Tzong-Rong , Lin Ya-Hui , Wei Zung-Hang
Published: February 2014

We demonstrate a design of using a wavy permalloy thin film as a cell sensing device for the purpose of single magnetic cell detection. The magnetoresistance curve (MR curve) differs according to the single magnetic cell attached to the surface. By analyzing the MR curves, we can determine the sensing capability of the permalloy magnetic film device. Our results indicate that the sensitivity of the permalloy film sensing devices with wavy surface is much higher than the devices with flat surface. When a single magnetic cell is captured by the wavy surface of the permalloy film, the switching field of the film increase which is caused by the stray field of the magnetic cell. We discover that the highest sensitivity occurs when the direction of the magnetic field is along the Z-axis, and there is significant potential for the application of cell detection.
Distribution of nanoscale nuclei in the amorphous dome of a phase change random access memory
Authors: Lee Bong-Sub , Darmawikarta Kristof , Raoux Simone , Shih Yen-Hao , Zhu Yu , Bishop Stephen G. , Abelson John R.
Published: February 2014

The nanoscale crystal nuclei in an amorphous Ge2Sb2Te5 bit in a phase change memory device were evaluated by fluctuation transmission electron microscopy. The quench time in the device (∼10 ns) afforded more and larger nuclei in the melt-quenched state than in the as-deposited state. However, nuclei were even more numerous and larger in a test structure with a longer quench time (∼100 ns), verifying the prediction of nucleation theory that slower cooling produces more nuclei. It also demonstrates that the thermal design of devices will strongly influence the population of nuclei, and thus the speed and data retention characteristics.
A contactless microwave-based diagnostic tool for high repetition rate laser systems
Authors: Braggio C. , Borghesani A. F.
Published: February 2014

We report on a novel electro-optic device for the diagnostics of high repetition rate laser systems. It is composed of a microwave receiver and of a second order nonlinear crystal, whose irradiation with a train of short laser pulses produces a time-dependent polarization in the crystal itself as a consequence of optical rectification. This process gives rise to the emission of microwave radiation that is detected by a receiver and is analyzed to infer the repetition rate and intensity of the pulses. We believe that this new method may overcome some of the limitations of photodetection techniques.
Computational efficiency improvement with Wigner rotation technique in studying atoms in intense few-cycle circularly polarized pulses
Authors: Yuan Minghu , Lü Rui , Feng Liqiang , Chu Tianshu
Published: February 2014

We show that by introducing Wigner rotation technique into the solution of time-dependent Schrödinger equation in length gauge, computational efficiency can be greatly improved in describing atoms in intense few-cycle circularly polarized laser pulses. The methodology with Wigner rotation technique underlying our openMP parallel computational code for circularly polarized laser pulses is described. Results of test calculations to investigate the scaling property of the computational code with the number of the electronic angular basis function l as well as the strong field phenomena are presented and discussed for the hydrogen atom.
Textured metastable VO2 (B) thin films on SrTiO3 substrates with significantly enhanced conductivity
Authors: Chen Aiping , Bi Zhenxing , Zhang Wenrui , Jian Jie , Jia Quanxi , Wang Haiyan
Published: February 2014

Textured metastable VO2 (B) thin films with a layered structure were grown on SrTiO3 (001) by pulsed laser deposition. The X-ray diffraction and transmission electron microscopy results indicate that VO2 (B) films exhibit c-axis out-of-plane, while the films have 4 possible in-plane matching relations. In addition, a small amount of VO2 (M) phase can co-grow in the VO2 (B) phase when the film thickness exceeds a threshold. The thick VO2 films on STO exhibit a sharp metal-insulator transition with an increase of electrical conductivity in two orders of magnitude. This study may provide an alternative approach to enhance the performance of insulating VO2 (B) based batteries with increased electrical conductivity by incorporating VO2 (M) phase in the VO2 (B) phase layered network.
On fractional differential inclusions with the Jumarie derivative
Authors: Kamocki Rafał , Obczyński Cezary
Published: February 2014

In the paper, fractional differential inclusions with the Jumarie derivative are studied. We discuss the existence and uniqueness of a solution to such problems. Our study relies on standard variational methods.
Dynamic magnetostrictive properties of magnetization-graded ferromagnetic material and application in magnetoelectric composite
Authors: Lu Caijiang , Li Ping , Wen Yumei , Yang Aichao , Yang Chao , Yang Jin , He Wei , Zhang Jitao , Li Wenli
Published: February 2014

This paper investigates the dynamic magnetostrictive properties in a laminate ferromagnetic material FeCuNbSiB/Ni (FN) consisting of a Nickel (Ni) plate and the Fe-based nanocrystalline alloy (FeCuNbSiB) foils. The resonant dynamic piezomagnetic coefficient (d33,m) is studied particularly in experiments. The experimental results demonstrate that the d33,m versus DC bias magnetic field data of FN show strong hysteretic and remanent behaviors. The zero-biased d33,m ranges from 5.14 to 42.7 (nm/A), depending on the numbers of FeCuNbSiB layer L. The maximum zero-biased d33,m of FN is 42.7 nm/A for FN with L = 4, which is ∼24.1 times larger than that of Ni. By combining FN with piezoelectric Pb(Zr0.52,Ti0.48)O3 (PZT), a giant zero-biased magnetoelectric voltage coefficient αME of ∼89.2 (V/cm Oe) is observed in composite FN/PZT/FN. Thus, the laminate magnetostrictive layer FN can be used for obtaining a self-biased magnetoelectric composite.
Negative differential resistance behavior in phosphorus-doped armchair graphene nanoribbon junctions
Authors: Zhou Yuhong , Zhang Daoli , Zhang Jianbing , Ye Cong , Miao Xiangshui
Published: February 2014

In this present work, we investigate the electronic transport properties of phosphorus-doped armchair graphene nanoribbon (AGNR) junctions by employing nonequilibrium Green's functions in combination with the density-function theory. Two phosphorus (P) atoms are considered to substitute the central carbon atom with the different width of AGNRs. The results indicate that the electronic transport behaviors are strongly dependent on the width of the P-doped graphene nanoribbons. The current-voltage characteristics of the doped AGNR junctions reveal an interesting negative differential resistance (NDR) and exhibit three distinct family (3 n, 3 n + 1, 3 n + 2) behaviors. These results display that P doping is a very good way to achieve NDR of the graphene nanoribbon devices.
Monolithic integration of common mode filters with electrostatic discharge protection on silicon/porous silicon hybrid substrate
Authors: Capelle M. , Billoué J. , Concord J. , Poveda P. , Gautier G.
Published: February 2014

This work presents the integration of a common mode filter with ElectroStatic Discharge protection on a silicon/porous silicon hybrid substrate. The porous silicon fabrication was performed after the integration of active components. Thus, a fluoropolymer hard mask was used to protect the active devices during anodization and can be easily removed without damaging the porous silicon. Electrical characterization results have shown fully operational components and an increase of performance with the hybrid substrate regarding to p+-type silicon. Indeed, the cutoff frequency was increased by 8.8 GHz when porous silicon was fabricated below the bump pads and the inductors. This improvement is a promising result to extend the application of RF components for future communication standards with silicon technology.
Magneto-optic effects in silica core microstructured fibers with a ferrofluidic cladding
Authors: Agruzov Petr M. , Pleshakov Ivan V. , Bibik Efim E. , Shamray Alexander V.
Published: February 2014

Studies of magneto-optic effects in ferrofluid-filled silica core microstructured optical fibers are reported. Amplitude, frequency, and polarization dependencies of magneto-optic responses were measured for both the transverse and longitudinal geometries of the applied AC magnetic field. Magneto-optic responses of two types, i.e., the fast and slow one, were observed. A qualitative model based on the Néel rotation for the fast response and on particle motion and agglomeration for the slow response is proposed.
Magnetic control of ferroelectric polarization in a self-formed single magnetoelectric domain of multiferroic Ba3NbFe3Si2O14
Authors: Lee Nara , Choi Young Jai , Cheong Sang-Wook
Published: February 2014

We have discovered strong magnetoelectric (ME) effects in the single chiral-helical magnetic state of single-crystalline langasite Ba3NbFe3Si2O14 that is crystallographically chiral. The ferroelectric polarization, predominantly aligned along the a axis below the Nèel temperature of ∼27 K, changes in a highly non-linear fashion in the presence of in-plane magnetic fields (H) perpendicular to the a axis (H//b*). This ME effect as well as smaller ME effects in other directions exhibit no poling dependence, suggesting the presence of a self-formed single ME domain. In addition, these ME effects accompany no-measurable hysteresis, which is crucial for many technological applications.
Advanced photovoltaic/hydro hybrid renewable energy system for remote areas
Authors: Meshram Sweeka , Agnihotri Ganga , Gupta Sushma
Published: February 2014

This paper presents modeling and simulation of the advanced photovoltaic (PV)/hydro based Hybrid Renewable Energy System (HRES) to electrify such isolated/remote areas, where grid accessibility is not possible. For 7.5 kW hydro generation system, a Self Excited Induction Generator (SEIG) with improved technique is used to optimize the utilization of hydro power. To achieve this aim, an uncontrolled bridge rectifier coupled with Hydro side Voltage Source Inverter is implemented for the SEIG based advanced hydro system. The PV system is configured by PV array, battery, DC/DC converter, maximum power point tracking controller, and PV side Voltage Source Inverter. A Constant Current Control scheme is developed in this paper to control active and reactive power flow and to synchronize hydro and PV systems. The proposed system uses fewer controlled switches, hence complexity of control has been reduced and system has higher efficiency and lower switching losses. The performance analysis of the HRES has been done to authenticate the existence of the system using the MATLAB software and results demonstrate that power quality of the proposed system is better and HRES is able to put into services.
High-field quasi-ballistic transport in AlGaN/GaN heterostructures
Authors: Danilchenko B. A. , Tripachko N. A. , Belyaev A. E. , Vitusevich S. A. , Hardtdegen H. , Lüth H.
Published: February 2014

Mechanisms of electron transport formation in 2D conducting channels of AlGaN/GaN heterostructures in extremely high electric fields at 4.2 K have been studied. Devices with a narrow constriction for the current flow demonstrate high-speed electron transport with an electron velocity of 6.8 × 107 cm/s. Such a velocity is more than two times higher than values reported for conventional semiconductors and about 15% smaller than the limit value predicted for GaN. Superior velocity is attained in the channel with considerable carrier reduction. The effect is related to a carrier runaway phenomenon. The results are in good agreement with theoretical predictions for GaN-based materials.
In-situ scanning electron microscope observation of electromigration-induced void growth in 30 nm ½ pitch Cu interconnect structures
Authors: Vanstreels K. , Czarnecki P. , Kirimura T. , Siew Y. K. , De Wolf I. , Bömmels J. , Tőkei Zs. , Croes K.
Published: February 2014

In-situ electromigration tests have been performed inside a scanning electron microscope on 30 nm wide single damascene interconnects without vias, where a good resolution was obtained and drift velocities during void growth could be measured at 300 °C. These tests showed direct evidence that the cathode end of the line, where a polycrystalline grain cluster encounters a bigger grain, can act as a flux divergent point of Cu diffusion. Moreover, it was found that a thicker barrier suppresses barrier/interface diffusivity of Cu atoms, thereby slowing down electromigration-induced void growth. It was also demonstrated that Cobalt based metal caps are beneficial to electromigration for advanced interconnects where thinner barriers are required.
A method to determine silver partitioning and lability in soils
Authors: Settimio Lara , McLaughlin Mike J. , Kirby Jason K. , Langdon Kate A.
Published: February 2014

Environmental context Soils contaminated with silver can have detrimental environmental effects because of silver’s toxicity to a range of soil-dwelling organisms. The total concentration of silver in soil, however, is often not a good indicator of potential toxicity as it does not account for variations in bioavailability. We report a method for soil analysis that measures the amount of silver available for uptake by soil-dwelling organisms, and hence could provide data that better reflect potential toxicity. Abstract There is increasing potential for pollution of soils by silver because of an increased use of this metal in consumer and industrial products. Silver may undergo reactions with soil components that mitigate its availability and potential toxicity, so that the total concentration of this metal in soil is not a useful indicator of potential risk. We developed an isotopic dilution method to simultaneously measure the partitioning (Kd-value) and lability (E-value) of Ag in soils, using the 110mAg isotope. An equilibration solution containing 10mM Ca(NO3)2 was used along with a cation exchange resin to correct for possible interferences from non-isotopically exchangeable Ag associated with soil colloids in suspension (Er-value). The quantification limits for Kd and Er will depend on the amounts of radioisotope spiked and daily detection limits of inductively coupled plasma-mass spectrometry instrumentation but are typically >4000Lkg–1 and <0.92mgkg–1. Measurement of Kd values for Ag in a range of soils indicated strong partitioning to the solid phase is positively associated with soil cation-exchange capacity or total organic carbon and pH. The concentrations of labile Ag in soils geogenically enriched in Ag were not detectable indicating occlusion of the Ag within poorly soluble solid phases. Measurement of labile Ag in soils spiked with a soluble Ag salt and aged for 2 weeks indicated rapid conversion of soluble Ag into non-isotopically exchangeable forms, either irreversibly adsorbed or precipitated in the soil. These results indicate that measurement of labile Ag will be important to estimate toxicity risks to soil organisms or to predict bioaccumulation through the food chain.
Relationship between fire-return interval and mulga (Acacia aneura) regeneration in the Gibson Desert and Gascoyne–Murchison regions of Western Australia
Authors: Ward Bruce G. , Bragg Thomas B. , Hayes Barbara A.
Published: February 2014

A study of 26 burnt mulga (Acacia aneura) stands was conducted from 2003 to 2012 in the Gibson Desert and eastern Gascoyne–Murchison region of Western Australia to assess the effect of fire interval on seedling regeneration. Tree-ring analysis and Landsat satellite imagery identified mulga stands with fire intervals ranging from 3 to 52 years. Results show fire-return intervals less than 20 years produce 2–3-year-old seedling regeneration lower than 50% of the original adult stand population (average juvenile-to-adult ratio=0.49). In total, 6 of the 26 stands sampled had reburnt within 3 to 10 years of the previous burn, a consequence of increased plant growth associated with higher rainfall. For all fires, summer fires were larger and more frequent (24 of 35 fires recorded, median fire size=150km2) than spring fires (median fire size=91km2). This study emphasises the important role of fire in maintaining the diversity and vigour of the mulga–Triodia ecosystem but indicates a minimum fire-return interval of 26 years to maintain mulga populations.
The Relationship between Interannual Climate Variability and Juvenile Eastern Oyster Abundance at a Regional Scale in Chesapeake Bay
Authors: Kimmel David G. , Tarnowski Mitchell , Newell Roger I. E.
Published: February 2014

The eastern oyster, Crassostrea virginica, is an important ecological and commercial species along the Eastern Seaboard of North America, although its abundance in Chesapeake Bay (Maryland and Virginia) has declined precipitously since the mid-1800s. Management activities, including efforts to enhance larval settlement, to rebuild the Chesapeake Bay eastern oyster population have met with limited success. Since 1939, juvenile oyster abundance has been measured at oyster bars in the northern portion of Chesapeake Bay. Prior analyses of those data indicate that juvenile oyster abundance is influenced by environmental conditions, which are related to regional climate. We quantified a regional scale (1,000 km2) climate signal using a synoptic climatology approach by identifying predominant weather patterns. We related these weather patterns to Susquehanna River freshwater discharge, a major influencing factor on Chesapeake Bay salinity, and the Palmer Hydrological Drought Index (PHDI), an indicator of the overall wetness or dryness of a given region. We developed path analysis models that linked weather patterns to Susquehanna River discharge and thence to either the PHDI or ambient salinity and water temperature and finally to juvenile oyster abundance in one of four preidentified spatial groupings. The path models indicated that weather patterns that produce wet conditions, leading to a higher PHDI and lower salinity, resulted in reduced juvenile oyster abundance; weather patterns that produce dry conditions that decreased the PHDI and increased salinity resulted in higher juvenile oyster abundance. Our results indicate that regions of higher juvenile oyster abundance may be predicted several months in advance using the path model. These predictions can be used to increase the effectiveness of oyster restoration efforts by indicating where hard substrate added to oyster bars in the four regions is likely to result in greater than average numbers of juvenile oysters.

Received January 16, 2013; accepted July 24, 2013

Published online December 3, 2013
Climate Change, Migration Phenology, and Fisheries Management Interact with Unanticipated Consequences
Authors: Peer A. C. , Miller T. J.
Published: February 2014

Accumulating evidence indicates that as global temperatures rise, reproductive behaviors, including migrations, are occurring earlier across a range of taxa. Alone, these changes are ecologically important; however, for some fish populations, management practices may unknowingly interact with climate-induced changes in reproductive phenology, leading to unanticipated changes in fishing mortality. The potential for such an interaction exists for the Chesapeake Bay Striped Bass Morone saxatilis fishery, which opens on the same week each year during the spawning season. Earlier migrants spawn before the fishery opens; however, later migrants are vulnerable to fishing before they reach the spawning grounds. Consequently, if there are climate-induced changes in Striped Bass spawning phenology, unexpected levels of fishing mortality may occur for egg-bearing, prespawn females. To evaluate the potential consequences of this temporally fixed fishing season, we analyzed a time series of gill-net catch data using an inference-based modeling approach to identify the environmental cues driving variation in the migratory timing of Striped Bass onto their two primary spawning grounds. We hypothesized that factors driving migratory timing would also influence the proportion of egg-bearing, prespawn females caught in the fishery each year. Results indicated that spring water temperature was the primary factor influencing the timing of movement onto spawning grounds, with higher temperatures resulting in early migrations. Importantly, our results indicated that in cool years, when females moved onto the spawning grounds later, more egg-bearing females were caught in the fishery before they could spawn. This situation provides impetus for establishing management approaches that reduce potential climate-induced variability in fishing mortality in the Chesapeake Bay and fisheries around the globe.

Received December 20, 2012; accepted September 5, 2013

Published online February 10, 2014
Automated Detection and Tracking of Adult Pacific Lampreys in Underwater Video Collected at Snake and Columbia River Fishways
Authors: Negrea Cristi , Thompson Donald E. , Juhnke Steven D. , Fryer Derek S. , Loge Frank J.
Published: February 2014

To reduce staffing demands and enhance observational accuracy, we designed, implemented, and tested a computerized system for processing underwater video clips captured by static cameras and removing “quiet” frames in which no activity is detected. When the system detects activity, it tracks and counts the moving object. The implementation uses an adaptive background-subtraction algorithm for detection and motion prediction for tracking. The system can be used to reduce the amount of video that must be reviewed by personnel, and it can produce total fish passage counts through the monitored area. The automated system reduced the total number of video hours requiring review by an average of 87.5% for count window videos and 83.5% for videos of picketed leads and lamprey passage orifices. The software detected 98.6% of the 144 Pacific Lampreys Entosphenus tridentatus that were observed in 185 h of raw video. Because the system is fully automated, monitoring requirements are negligible, and the cost reduction for fish monitoring is proportional to the number of quiet frames removed.

Received March 27, 2013; accepted September 23, 2013

Published online January 30, 2014
Summer Thermal Thresholds of Fish Community Transitions in Connecticut Streams
Authors: Beauchene Mike , Becker Mary , Bellucci Christopher J. , Hagstrom Neal , Kanno Yoichiro
Published: February 2014

Thermal tolerances have been studied for individual fish species but few have investigated how stream fish assemblages respond along a temperature gradient and which thermal ranges act as a threshold, triggering discernible community change. The purpose of this study was to define summer temperature thresholds of fish community transitions in Connecticut streams. The program Threshold Indicator Taxa Analysis suggested that the coldwater class had a June–August mean water temperature < 18.29°C, the coolwater class 18.29–21.70°C, and a warmwater class > 21.70°C. Significant indicator species of coldwater streams were Slimy Sculpin Cottus cognatus and Brook Trout Salvelinus fontinalis. Significant indicator species of warmwater streams were Cutlip Minnow Exoglossum maxillingua, Smallmouth Bass Micropterus dolomieu, Rock Bass Ambloplites rupestris, Brown Bullhead Ameiurus nebulosus, Redbreast Sunfish Lepomis auritus and Yellow Bullhead A. natalis. The narrow 3.41°C temperature range between the coldwater and warmwater thresholds was designated as a coolwater transition zone, with potential for the presence of both coldwater and warmwater species and lack of species uniquely associated with this thermal range. Our approach based on a robust set of water temperature and fish community data should be applicable to other temperate regions and will be useful for informing development of thermal criteria, application of multimetric indices, and planning for anticipated effects of climate change.

Received July 2, 2013; accepted October 8, 2013

Published online January 30, 2014
Monitoring Stock-Specific Abundance, Run Timing, and Straying of Chinook Salmon in the Columbia River Using Genetic Stock Identification (GSI)
Authors: Hess Jon E. , Whiteaker John M. , Fryer Jeffrey K. , Narum Shawn R.
Published: February 2014

Genetic stock identification (GSI) provides a method of characterizing stock-specific abundance, run timing, and straying as they pertain to the population demographics and behavior of both hatchery and wild fish and thus assists with fisheries management. In this study, tissues were collected and genotyped at 13 microsatellite loci from adult Chinook Salmon Oncorhynchus tshawytscha that passed Bonneville Dam during four consecutive migration years (2004–2007). GSI methods were used to estimate the proportions of stocks in a broad genetic baseline, with high-density coverage of Chinook Salmon across the eastern Pacific Rim. The estimates of abundance for interior Columbia River stocks showed widespread decline consistent with a shift to poor ocean conditions during the years when the fish in this study were at sea, but divergent stock- and age-specific patterns were also observed. For example, the upper Columbia River spring-run stock experienced a unique net gain in abundance during this period, and the interior Columbia River summer–fall-run stock experienced a delayed decline of 4-year-olds. Stocks with early run timing shifted to later migrations. However, run timing distributions did not shift unidirectionally for all stocks across years, and stock membership in three major run timing categories was maintained. Of 9,215 total adults sampled, 27 (0.3%) were out-of-basin strays and a quarter of the strays were putatively of wild origin. The general concordance of GSI results with those based on more traditional methods supports the effectiveness of GSI as a tool for fisheries management.

Received May 5, 2013; accepted October 23, 2013

Published online February 10, 2014
Minimally Invasive Delivery of a Novel Direct Epicardial Assist Device in a Porcine Heart Failure Model
Authors: McGarvey Jeremy R. , Shimaoka Toru , Takebayashi Satoshi , Aoki Chikashi , Kondo Norihiro , Takebe Manabu , Zsido Gerald A. , Jassar Arminder , Gorman Joseph H. , Pilla James J. , Gorman Robert C.
Published: February 2014

Objective

Despite advances in design, modern ventricular assist device placement involves median sternotomy and cardiopulmonary bypass and is associated with infectious/embolic complications. In this study, we examine the feasibility and function of a novel minimally invasive, non–blood-contacting epicardial assist device in a porcine ischemic cardiomyopathy model.

Methods

Feasibility was first tested in an ex vivo thoracoscopic trainer box with slaughterhouse hearts. Five male Yorkshire swine underwent selective ligation of the circumflex artery to create a posterolateral infarct Twelve weeks after infarct, all animals underwent left minithoracotomy. A custom inflatable bladder was positioned over the epicardial surface of the infarct and firmly secured to the surrounding border zone myocardium with polypropylene mesh and minimally invasive mesh tacks. An external gas pulsation system actively inflated and deflated the bladder in synchrony with the cardiac cycle. All animals then underwent cardiac magnetic resonance imaging to assess ventricular function.

Results

All subjects successfully underwent off-pump placement of the epicardial assist device via minithoracotomy. Ejection fraction significantly improved from 29.1% ± 4.8% to 39.6% ± 4.23% ( P < 0.001) when compared with pretreatment. End-systolic volume decreased (76.6 ± 13.3 mL vs 62.4 ± 12.0 mL, P < 0.001) and stroke volume increased (28.6 ± 3.4 mL vs 37.9 ± 3.1 mL, P < 0.05) when assisted. No change was noted in end-diastolic volume (105.1 ± 11.4 vs 100.3 ± 12.7). On postmortem examination, mesh fixation and device position were excellent in all cases. No adverse events were encountered.

Conclusions

Directed epicardial assistance improves ventricular function in a porcine ischemic cardiomyopathy model and may provide a safe alternative to currently available ventricular assist device therapies. Further, the technique used for device positioning and fixation suggests that an entirely thoracoscopic approach is possible.
The structure and micromechanics of elastic tissue
Authors: Green Ellen M. , Mansfield Jessica C. , Bell James S. , Winlove C. Peter
Published: February 2014

Elastin is a major component of tissues such as lung and blood vessels, and endows them with the long-range elasticity necessary for their physiological functions. Recent research has revealed the complexity of these elastin structures and drawn attention to the existence of extensive networks of fine elastin fibres in tissues such as articular cartilage and the intervertebral disc. Nonlinear microscopy, allowing the visualization of these structures in living tissues, is informing analysis of their mechanical properties. Elastic fibres are complex in composition and structure containing, in addition to elastin, an array of microfibrillar proteins, principally fibrillin. Raman microspectrometry and X-ray scattering have provided new insights into the mechanisms of elasticity of the individual component proteins at the molecular and fibrillar levels, but more remains to be done in understanding their mechanical interactions in composite matrices. Elastic tissue is one of the most stable components of the extracellular matrix, but impaired mechanical function is associated with ageing and diseases such as atherosclerosis and diabetes. Efforts to understand these associations through studying the effects of processes such as calcium and lipid binding and glycation on the mechanical properties of elastin preparationsin vitrohave produced a confusing picture, and further efforts are required to determine the molecular basis of such effects.
Impact of heating on passive and active biomechanics of suspended cells
Authors: Chan C. J. , Whyte G. , Boyde L. , Salbreux G. , Guck J.
Published: February 2014

A cell is a complex material whose mechanical properties are essential for its normal functions. Heating can have a dramatic effect on these mechanical properties, similar to its impact on the dynamics of artificial polymer networks. We investigated such mechanical changes by the use of a microfluidic optical stretcher, which allowed us to probe cell mechanics when the cells were subjected to different heating conditions at different time scales. We find that HL60/S4 myeloid precursor cells become mechanically more compliant and fluid-like when subjected to either a sudden laser-induced temperature increase or prolonged exposure to higher ambient temperature. Above a critical temperature of 52 ± 1°C, we observed active cell contraction, which was strongly correlated with calcium influx through temperature-sensitive transient receptor potential vanilloid 2 (TRPV2) ion channels, followed by a subsequent expansion in cell volume. The change from passive to active cellular response can be effectively described by a mechanical model incorporating both active stress and viscoelastic components. Our work highlights the role of TRPV2 in regulating the thermomechanical response of cells. It also offers insights into how cortical tension and osmotic pressure govern cell mechanics and regulate cell-shape changes in response to heat and mechanical stress.
Structure of the extended-spectrum class C β-lactamase ADC-1 fromAcinetobacter baumannii
Authors: Bhattacharya Monolekha , Toth Marta , Antunes Nuno Tiago , Smith Clyde A. , Vakulenko Sergei B.
Published: February 2014

ADC-type class C β-lactamases comprise a large group of enzymes that are encoded by genes located on the chromosome ofAcinetobacter baumannii, a causative agent of serious bacterial infections. Overexpression of these enzymes rendersA. baumanniiresistant to various β-lactam antibiotics and thus severely compromises the ability to treat infections caused by this deadly pathogen. Here, the high-resolution crystal structure of ADC-1, the first member of this clinically important family of antibiotic-resistant enzymes, is reported. Unlike the narrow-spectrum class C β-lactamases, ADC-1 is capable of producing resistance to the expanded-spectrum cephalosporins, rendering them inactive againstA. baumannii. The extension of the substrate profile of the enzyme is likely to be the result of structural differences in the R2-loop, primarily the deletion of three residues and subsequent rearrangement of the A10a and A10b helices. These structural rearrangements result in the enlargement of the R2 pocket of ADC-1, allowing it to accommodate the bulky R2 substituents of the third-generation cephalosporins, thus enhancing the catalytic efficiency of the enzyme against these clinically important antibiotics.
The structure of Rv2372c identifies an RsmE-like methyltransferase from Mycobacterium tuberculosis
Authors: Kumar Atul , Kumar Santosh , Taneja Bhupesh
Published: February 2014

U1498 of 16S rRNA plays an important role in translation fidelity as well as in antibiotic response. U1498 is present in a methylated form in the decoding centre of the ribosome. In this study, Rv2372c from Mycobacterium tuberculosis has been identified as an RsmE-like methyltransferase which specifically methylates U1498 of 16S rRNA at the N3 position and can complement RsmE-deleted Escherichia coli. The crystal structure of Rv2372c has been determined, and reveals that the protein belongs to a distinct class in the SPOUT superfamily and exists as a dimer. The deletion of critical residues at the C-terminus of Rv2372c leads to an inability of the protein to form stable dimers and to abolition of the methyltransferase activity. A ternary model of Rv2372c with its cofactor S-adenosylmethionine (SAM) and the 16S rRNA fragment 148716S rRNA1510 helps to identify binding pockets for SAM (in the deep trefoil knot) and substrate RNA (at the dimer interface) and suggests an SN2 mechanism for the methylation of N3 of U1498 in 16S rRNA.
The structure of cytomegalovirus immune modulator UL141 highlights structural Ig-fold versatility for receptor binding
Authors: Nemčovičová Ivana , Zajonc Dirk M.
Published: February 2014

Natural killer (NK) cells are critical components of the innate immune system as they rapidly detect and destroy infected cells. To avoid immune recognition and to allow long-term persistence in the host, Human cytomegalovirus (HCMV) has evolved a number of genes to evade or inhibit immune effector pathways. In particular, UL141 can inhibit cell-surface expression of both the NK cell-activating ligand CD155 as well as the TRAIL death receptors (TRAIL-R1 and TRAIL-R2). The crystal structure of unliganded HCMV UL141 refined to 3.25 Å resolution allowed analysis of its head-to-tail dimerization interface. A `dimerization-deficient' mutant of UL141 (ddUL141) was further designed, which retained the ability to bind to TRAIL-R2 or CD155 while losing the ability to cross-link two receptor monomers. Structural comparison of unliganded UL141 with UL141 bound to TRAIL-R2 further identified a mobile loop that makes intimate contacts with TRAIL-R2 upon receptor engagement. Superposition of the Ig-like domain of UL141 on the CD155 ligand T-cell immunoreceptor with Ig and ITIM domains (TIGIT) revealed that UL141 can potentially engage CD155 similar to TIGIT by using the C′C′′ and GF loops. Further mutations in the TIGIT binding site of CD155 (Q63R and F128R) abrogated UL141 binding, suggesting that the Ig-like domain of UL141 is a viral mimic of TIGIT, as it targets the same binding site on CD155 using similar `lock-and-key' interactions. Sequence alignment of the UL141 gene and its orthologues also showed conservation in this highly hydrophobic (L/A)X
6G `lock' motif for CD155 binding as well as conservation of the TRAIL-R2 binding patches, suggesting that these host–receptor interactions are evolutionary conserved.
Methyl 1-benzyl-5-methyl-2,4-diphenyl-1H-pyrrole-3-carboxylate
Authors: Lopchuk Justin M. , Gribble Gordon W. , Jasinski Jerry P.
Published: February 2014

In the title compound, C26H23NO2, the dihedral angles between the pyrrole ring and the two phenyl rings are 58.1 (6) and 71.5 (5)°. The mean planes of the 5-methylbenzene ring and the carboxyl group are twisted by 89.5 (3) and 22.1 (9)°, respectively, from the pyrrole ring. In the crystal, weak C—H...O interactions lead to supramolecular layers in theabplane.
4-Nitrophthalonitrile
Authors: Jan Chin Yee , Shamsudin Norzianah Binti Haji , Tan Ai Ling , Young David J. , Ng Seik Weng , Tiekink Edward R. T.
Published: February 2014

In the title compound, C8H3N3O2(systematic name: 4-nitrobenzene-1,2-dicarbonitrile), the nitro group is twisted out of the plane of the benzene ring to which it is attached [O—N—Cring—Cringtorsion angle = 9.80 (13)°]. In the crystal packing, supramolecular layers with a zigzag topology in theacplane are sustained by C—H...N interactions.
2-((1E)-1-{2-[(2Z)-4-(4-Bromophenyl)-3-phenyl-2,3-dihydro-1,3-thiazol-2-ylidene]hydrazin-1-ylidene}ethyl)pyridin-1-ium bromide monohydrate
Authors: Mague Joel T. , Mohamed Shaaban K. , Akkurt Mehmet , Abd El-Alaziz Ahmed T. , Albayati Mustafa R.
Published: February 2014

In the title hydrated molecular salt, C22H18BrN4S+·Br−·H2O, the aromatic rings make dihedral angles of 14.20 (12), 34.29 (10) and 68.75 (11)° with the thiazole ring. In the crystal, molecules are linked into chains running parallel to theaaxis by association of the bromide ions and the water molecules of crystallization with the cationsviaN—H...O, O—H...Br, C—H...N and C—H...Br hydrogen-bonding interactions. C—H...π and C—Br...π [3.7426 (11) Å, 161.73 (7)°] interactions are also observed, forming infinite chains extending along theb-axis direction.
(Methoxymethylidene)dimethylazanium tetraphenylborate acetonitrile monosolvate
Authors: Tiritiris Ioannis , Saur Stefan , Kantlehner Willi
Published: February 2014

In the cation of the title salt, C4H10NO+·C24H20B−·C2H3N, the C—N bond lengths are 1.2864 (16), 1.4651 (17) and 1.4686 (16) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.2978 (15) Å shows double-bond character, pointing towards charge delocalization within the NCO plane of the iminium ion. C—H...π interactions are present between the methine H atom and two of the phenyl rings of the tetraphenylborate ion. The latter forms an aromatic pocket in which the cation is embedded. The iminium ion is further connected through a C—H...N hydrogen bond to the acetonitrile molecule. This leads to the formation of a two-dimensional supramolecular pattern along thebcplane.
4-Thiocarbamoylpyridin-1-ium iodide
Authors: Shotonwa Ibukun O. , Boeré René T.
Published: February 2014

The title salt, C6H7N2S+·I−, crystallizes with two independent cations and two anions in the asymmetric unit. In one of the cations, the dihedral angle between the pyridinium ring and the thioamide group is 28.9 (2)°; in the other it is 33.5 (2)°. In the crystal, N—H...S and C—H...S hydrogen bonds link the independent cations into pairs. These pairs form a three-dimensional network through additional N—H...I and C—H...I hydrogen bonds to the anions.
2-(4,5-Dimethoxy-2-nitrophenyl)-4-methoxy-3-methyl-9-phenylsulfonyl-9H-carbazole
Authors: Narayanan P. , Sethusankar K. , Saravanan Velu , Mohanakrishnan Arasambattu K.
Published: February 2014

In the title compound, C28H24N2O7S, the carbazole system is essentially planar, with a maximum deviation of 0.0644 (19) Å for the C atom connected to the 4,5-dimethoxy-2-nitrophenyl group. The dihedral angle between the carbazole moiety and the dimethoxy-substituted nitrophenyl ring is 58.55 (7)°. The sulfonyl group forms two intramolecular C—H...O bonds with the adjacent carbazole system, forming two cyclicS(6) motifs. In the crystal, molecules are linked along theaaxis in bands consisting of cyclicR33(15) motifs through two further C—H...O hydrogen bonds.