Tuning Chemical Potential Difference across Alternately Doped Graphene p-n Junctions for High-Efficiency Photodetection.

PubMed

Lin, Li; Xu, Xiang; Yin, Jianbo; Sun, Jingyu; Tan, Zhenjun; Koh, Ai Leen; Wang, Huan; Peng, Hailin; Chen, Yulin; Liu, Zhongfan

2016-07-13

Being atomically thin, graphene-based p-n junctions hold great promise for applications in ultrasmall high-efficiency photodetectors. It is well-known that the efficiency of such photodetectors can be improved by optimizing the chemical potential difference of the graphene p-n junction. However, to date, such tuning has been limited to a few hundred millielectronvolts. To improve this critical parameter, here we report that using a temperature-controlled chemical vapor deposition process, we successfully achieved modulation-doped growth of an alternately nitrogen- and boron-doped graphene p-n junction with a tunable chemical potential difference up to 1 eV. Furthermore, such p-n junction structure can be prepared on a large scale with stable, uniform, and substitutional doping and exhibits a single-crystalline nature. This work provides a feasible method for synthesizing low-cost, large-scale, high efficiency graphene p-n junctions, thus facilitating their applications in optoelectronic and energy conversion devices.

Systematic study of the fusion barriers using different proximity-type potentials for N=Z colliding nuclei: New extensions

NASA Astrophysics Data System (ADS)

Dutt, Ishwar; Puri, Rajeev K.

2010-04-01

By using 14 different versions and parametrizations of a proximity potential and two new versions of the potential proposed in this paper, we perform a comparative study of fusion barriers by studying 26 symmetric reactions. The mass asymmetry ηA=((A2-A1)/(A2+A1)), however, is very large. Our detailed investigation reveals that most of the proximity potentials reproduce experimental data within ±8% on average. A comparison of fusion cross sections indicates that Bass 80, AW 95, and Denisov DP potentials have a better edge than other potentials. We also propose new versions of the proximity potential as well as Denisov parametrized potential. These new versions improve agreement with the data.

Electrophysiological property and chemical sensitivity of primary afferent neurons that innervate rat whisker hair follicles.

PubMed

Ikeda, Ryo; Gu, Jianguo

2016-01-01

Whisker hair follicles are sensory organs that sense touch and perform tactile discrimination in animals, and they are sites where sensory impulses are initiated when whisker hairs touch an object. The sensory signals are then conveyed by whisker afferent fibers to the brain for sensory perception. Electrophysiological property and chemical sensitivity of whisker afferent fibers, important factors affecting whisker sensory processing, are largely not known. In the present study, we performed patch-clamp recordings from pre-identified whisker afferent neurons in whole-mount trigeminal ganglion preparations and characterized their electrophysiological property and sensitivity to ATP, serotonin and glutamate. Of 97 whisker afferent neurons examined, 67% of them are found to be large-sized (diameter ≥45 µm) cells and 33% of them are medium- to small-sized (diameter <45 µm) cells. Almost every large-sized whisker afferent neuron fires a single action potential but many (40%) small/medium-sized whisker afferent neurons fire multiple action potentials in response to prolonged stepwise depolarization. Other electrophysiological properties including resting membrane potential, action potential threshold, and membrane input resistance are also significantly different between large-sized and small/medium-sized whisker afferent neurons. Most large-sized and many small/medium-sized whisker afferent neurons are sensitive to ATP and/or serotonin, and ATP and/or serotonin could evoke strong inward currents in these cells. In contrast, few whisker afferent neurons are sensitive to glutamate. Our results raise a possibility that ATP and/or serotonin may be chemical messengers involving sensory signaling for different types of rat whisker afferent fibers.

Electric potential distributions at the interface between plasmasheet clouds

NASA Technical Reports Server (NTRS)

Evans, D. S.; Roth, M.; Lemaire, J.

1987-01-01

At the interface between two plasma clouds with different densities, temperatures, and/or bulk velocities, there are large charge separation electric fields which can be modeled in the framework of a collisionless theory for tangential discontinuities. Two different classes of layers were identified: the first one corresponds to (stable) ion layers which are thicker than one ion Lamor radius; the second one corresponds to (unstable) electron layers which are only a few electron Larmor radii thick. It is suggested that these thin electron layers with large electric potential gradients (up to 400 mV/m) are the regions where large-amplitude electrostatic waves are spontaneously generated. These waves scatter the pitch angles of the ambient plasmasheet electron into the atmospheric loss cone. The unstable electron layers can therefore be considered as the seat of strong pitch angle scattering for the primary auroral electrons.

Global warming potential of pavements

NASA Astrophysics Data System (ADS)

Santero, Nicholas J.; Horvath, Arpad

2009-09-01

Pavements comprise an essential and vast infrastructure system supporting our transportation network, yet their impact on the environment is largely unquantified. Previous life-cycle assessments have only included a limited number of the applicable life-cycle components in their analysis. This research expands the current view to include eight different components: materials extraction and production, transportation, onsite equipment, traffic delay, carbonation, lighting, albedo, and rolling resistance. Using global warming potential as the environmental indicator, ranges of potential impact for each component are calculated and compared based on the information uncovered in the existing research. The relative impacts between components are found to be orders of magnitude different in some cases. Context-related factors, such as traffic level and location, are also important elements affecting the impacts of a given component. A strategic method for lowering the global warming potential of a pavement is developed based on the concept that environmental performance is improved most effectively by focusing on components with high impact potentials. This system takes advantage of the fact that small changes in high-impact components will have more effect than large changes in low-impact components.

Prokaryotic Abundance and Activity in Permafrost of the Northern Victoria Land and Upper Victoria Valley (Antarctica).

PubMed

La Ferla, Rosabruna; Azzaro, Maurizio; Michaud, Luigi; Caruso, Gabriella; Lo Giudice, Angelina; Paranhos, Rodolfo; Cabral, Anderson S; Conte, Antonella; Cosenza, Alessandro; Maimone, Giovanna; Papale, Maria; Rappazzo, Alessandro Ciro; Guglielmin, Mauro

2017-08-01

Victoria Land permafrost harbours a potentially large pool of cold-affected microorganisms whose metabolic potential still remains underestimated. Three cores (BC-1, BC-2 and BC-3) drilled at different depths in Boulder Clay (Northern Victoria Land) and one sample (DY) collected from a core in the Dry Valleys (Upper Victoria Valley) were analysed to assess the prokaryotic abundance, viability, physiological profiles and potential metabolic rates. The cores drilled at Boulder Clay were a template of different ecological conditions (different temperature regime, ice content, exchanges with atmosphere and with liquid water) in the same small basin while the Dry Valleys site was very similar to BC-2 conditions but with a complete different geological history and ground ice type. Image analysis was adopted to determine cell abundance, size and shape as well as to quantify the potential viable and respiring cells by live/dead and 5-cyano-2,3-ditolyl-tetrazolium chloride staining, respectively. Subpopulation recognition by apparent nucleic acid contents was obtained by flow cytometry. Moreover, the physiological profiles at community level by Biolog-Ecoplate™ as well as the ectoenzymatic potential rates on proteinaceous (leucine-aminopeptidase) and glucidic (ß-glucosidase) organic matter and on organic phosphates (alkaline-phosphatase) by fluorogenic substrates were tested. The adopted methodological approach gave useful information regarding viability and metabolic performances of microbial community in permafrost. The occurrence of a multifaceted prokaryotic community in the Victoria Land permafrost and a large number of potentially viable and respiring cells (in the order of 10 4 -10 5 ) were recognised. Subpopulations with a different apparent DNA content within the different samples were observed. The physiological profiles stressed various potential metabolic pathways among the samples and intense utilisation rates of polymeric carbon compounds and carbohydrates, mainly in deep samples. The measured enzymatic activity rates suggested the potential capability of the microbial community to decompose proteins and polysaccharides. The microbial community seems to be appropriate to contribute to biogeochemical cycling in this extreme environment.

A combining rule calculation of the ground-state van der Waals potentials of the magnesium rare-gas complexes

NASA Astrophysics Data System (ADS)

Saidi, Samah; Alharzali, Nissrin; Berriche, Hamid

2017-04-01

The potential energy curves and spectroscopic constants of the ground-state of the Mg-Rg (Rg = He, Ne, Ar, Kr, and Xe) van der Waals complexes are generated by the Tang-Toennies potential model and a set of derived combining rules. The parameters of the model are calculated from the potentials of the homonuclear magnesium and rare-gas dimers. The predicted spectroscopic constants are comparable to other available theoretical and experimental results, except in the case of Mg-He, we note that there are large differences between various determinations. Moreover, in order to reveal relative differences between species more obviously we calculated the reduced potential of these five systems. The curves are clumped closely together, but at intermediate range the Mg-He reduced potential is clearly very different from the others.

Active commuting to school in Finland, the potential for physical activity increase in different seasons

PubMed Central

Kallio, Jouni; Turpeinen, Salla; Hakonen, Harto; Tammelin, Tuija

2016-01-01

Background Active commuting to school (ACS) can be a significant source of physical activity and provide many health benefits. Objective This study identified the potential to increase physical activity levels by promoting ACS in Finnish schools and evaluated the effects of season, distance and age on ACS. Design Data were collected with a questionnaire from 5,107 students, aged 10–16, in 45 comprehensive schools in Finland. The distance and the mode of transport to school in different seasons were self-reported. Results The prevalence of ACS was over 80% during spring/fall for those living 0–5 km from school. ACS was inversely associated with the distance to school and was lower in winter compared to spring and fall. Cycling is less common in winter, especially among girls and younger students. The potential for increasing students’ physical activity levels via ACS seems to be largest in winter, especially among students living 1–5 km from school. The variation in the prevalence of ACS between schools was large, especially in winter. Conclusions When planning interventions to promote ACS, one is encouraged to acknowledge and evaluate the potential in the selected target schools in different seasons. The potential varies largely between schools and seasons and is highly dependent on students’ commuting distances. PMID:27924739

A fast time-difference inverse solver for 3D EIT with application to lung imaging.

PubMed

Javaherian, Ashkan; Soleimani, Manuchehr; Moeller, Knut

2016-08-01

A class of sparse optimization techniques that require solely matrix-vector products, rather than an explicit access to the forward matrix and its transpose, has been paid much attention in the recent decade for dealing with large-scale inverse problems. This study tailors application of the so-called Gradient Projection for Sparse Reconstruction (GPSR) to large-scale time-difference three-dimensional electrical impedance tomography (3D EIT). 3D EIT typically suffers from the need for a large number of voxels to cover the whole domain, so its application to real-time imaging, for example monitoring of lung function, remains scarce since the large number of degrees of freedom of the problem extremely increases storage space and reconstruction time. This study shows the great potential of the GPSR for large-size time-difference 3D EIT. Further studies are needed to improve its accuracy for imaging small-size anomalies.

[A study of complexity and power spectrum of cortical EEG and hippocampal potential in rats under different behavioral states].

PubMed

Feng, Zhou-yan; Zheng, Xiao-xiang

2002-08-01

Objective. To study the complexity and the power spectrum of cortical EEG and hippocampal potential in rats under waking and sleep states. Method. Cortical EEG and hippocampal potential were collected by implanted electrodes in freely moving rats. Algorithmic complexity (Kc), approximate entropy (ApEn), power spectral density (PSD) and gravity frequency of PSD of the potential waves were calculated. Result. The complexity of hippocampal potential was higher than that of cortical EEG under every state. The complexity of cortical EEG was lowest under the state of non rapid eye movement (NREM) sleep. The complexity of hippocampal potential was highest under waking state. The total power of both potentials in 0.5- 30 Hz frequency band showed their highest values under NREM state. Conclusion. The values of Kc and ApEn are closely related to the distributions of PSD. When there are evident peaks in PSD, the complexities of signals will decrease. The complexities may be used to distinguish the difference between cortical EEG and hippocampal potential, or large differences between the same kind of potentials under different behavioral states.

Microbial production of volatile sulphur compounds in the large intestine of pigs fed two different diets.

PubMed

Poulsen, H V; Jensen, B B; Finster, K; Spence, C; Whitehead, T R; Cotta, M A; Canibe, N

2012-07-01

  To investigate the production of volatile sulphur compounds (VSC) in the segments of the large intestine of pigs and to assess the impact of diet on this production.   Pigs were fed two diets based on either wheat and barley (STD) or wheat and dried distillers grains with solubles (DDGS). Net production of VSC and potential sulphate reduction rate (SRR) (sulphate saturated) along the large intestine were determined by means of in vitro incubations. The net production rate of hydrogen sulphide and potential SRR increased from caecum towards distal colon and were significantly higher in the STD group. Conversely, the net methanethiol production rate was significantly higher in the DDGS group, while no difference was observed for dimethyl sulphide. The number of sulphate-reducing bacteria and total bacteria were determined by quantitative PCR and showed a significant increase along the large intestine, whereas no diet-related differences were observed.   VSC net production varies widely throughout the large intestine of pigs and the microbial processes involved in this production can be affected by diet.   This first report on intestinal production of all VSC shows both spatial and dietary effects, which are relevant to both bowel disease- and odour mitigation research. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

The production of large and small wildfires

Treesearch

David T. Butry; Marcia Gumpertz; Marc G. Genton

2008-01-01

N aturallarge (catastrophic) disturbances are important because of their potential long-lasting impact on their surroundings, but underlying differences between frequent small and less common large disturbances are not well understood (Turner and Dale 1997, Romme et al. 1998, Turner and Dale 1998, chapter 4 of this book). Smaller disturbances may be better understood...

The potential for agricultural land use change to reduce flood risk in a large watershed

USDA-ARS?s Scientific Manuscript database

Effects of agricultural land management practices on surface runoff are evident at local scales, but evidence for watershed-scale impacts is limited. In this study, we used the Soil and Water Assessment Tool model to assess changes in downstream flood risks under different land uses for the large, ...

Pronounced differences in genetic structure despite overall ecological similarity for two Ambystoma salamanders in the same landscape

Treesearch

Andrew R. Whiteley; Kevin McGarigal; Michael K. Schwartz

2014-01-01

Studies linking genetic structure in amphibian species with ecological characteristics have focused on large differences in dispersal capabilities. Here, we test whether two species with similar dispersal potential but subtle differences in other ecological characteristics also exhibit strong differences in genetic structure in the same landscape. We examined eight...

Rubisco Catalytic Properties and Temperature Response in Crops1

PubMed Central

2016-01-01

Rubisco catalytic traits and their thermal dependence are two major factors limiting the CO2 assimilation potential of plants. In this study, we present the profile of Rubisco kinetics for 20 crop species at three different temperatures. The results largely confirmed the existence of significant variation in the Rubisco kinetics among species. Although some of the species tended to present Rubisco with higher thermal sensitivity (e.g. Oryza sativa) than others (e.g. Lactuca sativa), interspecific differences depended on the kinetic parameter. Comparing the temperature response of the different kinetic parameters, the Rubisco Km for CO2 presented higher energy of activation than the maximum carboxylation rate and the CO2 compensation point in the absence of mitochondrial respiration. The analysis of the Rubisco large subunit sequence revealed the existence of some sites under adaptive evolution in branches with specific kinetic traits. Because Rubisco kinetics and their temperature dependency were species specific, they largely affected the assimilation potential of Rubisco from the different crops, especially under those conditions (i.e. low CO2 availability at the site of carboxylation and high temperature) inducing Rubisco-limited photosynthesis. As an example, at 25°C, Rubisco from Hordeum vulgare and Glycine max presented, respectively, the highest and lowest potential for CO2 assimilation at both high and low chloroplastic CO2 concentrations. In our opinion, this information is relevant to improve photosynthesis models and should be considered in future attempts to design more efficient Rubiscos. PMID:27329223

Rubisco Catalytic Properties and Temperature Response in Crops.

PubMed

Hermida-Carrera, Carmen; Kapralov, Maxim V; Galmés, Jeroni

2016-08-01

Rubisco catalytic traits and their thermal dependence are two major factors limiting the CO2 assimilation potential of plants. In this study, we present the profile of Rubisco kinetics for 20 crop species at three different temperatures. The results largely confirmed the existence of significant variation in the Rubisco kinetics among species. Although some of the species tended to present Rubisco with higher thermal sensitivity (e.g. Oryza sativa) than others (e.g. Lactuca sativa), interspecific differences depended on the kinetic parameter. Comparing the temperature response of the different kinetic parameters, the Rubisco Km for CO2 presented higher energy of activation than the maximum carboxylation rate and the CO2 compensation point in the absence of mitochondrial respiration. The analysis of the Rubisco large subunit sequence revealed the existence of some sites under adaptive evolution in branches with specific kinetic traits. Because Rubisco kinetics and their temperature dependency were species specific, they largely affected the assimilation potential of Rubisco from the different crops, especially under those conditions (i.e. low CO2 availability at the site of carboxylation and high temperature) inducing Rubisco-limited photosynthesis. As an example, at 25°C, Rubisco from Hordeum vulgare and Glycine max presented, respectively, the highest and lowest potential for CO2 assimilation at both high and low chloroplastic CO2 concentrations. In our opinion, this information is relevant to improve photosynthesis models and should be considered in future attempts to design more efficient Rubiscos. © 2016 American Society of Plant Biologists. All Rights Reserved.

Determination of aerodynamic sensitivity coefficients based on the three-dimensional full potential equation

NASA Technical Reports Server (NTRS)

Elbanna, Hesham M.; Carlson, Leland A.

1992-01-01

The quasi-analytical approach is applied to the three-dimensional full potential equation to compute wing aerodynamic sensitivity coefficients in the transonic regime. Symbolic manipulation is used to reduce the effort associated with obtaining the sensitivity equations, and the large sensitivity system is solved using 'state of the art' routines. Results are compared to those obtained by the direct finite difference approach and both methods are evaluated to determine their computational accuracy and efficiency. The quasi-analytical approach is shown to be accurate and efficient for large aerodynamic systems.

Spatially distributed potential evapotranspiration modeling and climate projections.

PubMed

Gharbia, Salem S; Smullen, Trevor; Gill, Laurence; Johnston, Paul; Pilla, Francesco

2018-08-15

Evapotranspiration integrates energy and mass transfer between the Earth's surface and atmosphere and is the most active mechanism linking the atmosphere, hydrosphsophere, lithosphere and biosphere. This study focuses on the fine resolution modeling and projection of spatially distributed potential evapotranspiration on the large catchment scale as response to climate change. Six potential evapotranspiration designed algorithms, systematically selected based on a structured criteria and data availability, have been applied and then validated to long-term mean monthly data for the Shannon River catchment with a 50m 2 cell size. The best validated algorithm was therefore applied to evaluate the possible effect of future climate change on potential evapotranspiration rates. Spatially distributed potential evapotranspiration projections have been modeled based on climate change projections from multi-GCM ensembles for three future time intervals (2020, 2050 and 2080) using a range of different Representative Concentration Pathways producing four scenarios for each time interval. Finally, seasonal results have been compared to baseline results to evaluate the impact of climate change on the potential evapotranspiration and therefor on the catchment dynamical water balance. The results present evidence that the modeled climate change scenarios would have a significant impact on the future potential evapotranspiration rates. All the simulated scenarios predicted an increase in potential evapotranspiration for each modeled future time interval, which would significantly affect the dynamical catchment water balance. This study addresses the gap in the literature of using GIS-based algorithms to model fine-scale spatially distributed potential evapotranspiration on the large catchment systems based on climatological observations and simulations in different climatological zones. Providing fine-scale potential evapotranspiration data is very crucial to assess the dynamical catchment water balance to setup management scenarios for the water abstractions. This study illustrates a transferable systematic method to design GIS-based algorithms to simulate spatially distributed potential evapotranspiration on the large catchment systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Plasma sheath structure surrounding a large powered spacecraft

NASA Technical Reports Server (NTRS)

Mandell, M. J.; Jongeward, G. A.; Katz, I.

1984-01-01

Various factors determining the floating potential of a highly biased (about 4-kV) spacecraft in low earth orbit are discussed. While the common rule of thumb (90 percent negative; 10 percent positive) is usually a good guide, different biasing and grounding patterns can lead to high positive potentials. The NASCAP/LEO code can be used to predict spacecraft floating potential for complex three-dimensional spacecraft.

Smart grid initialization reduces the computational complexity of multi-objective image registration based on a dual-dynamic transformation model to account for large anatomical differences

NASA Astrophysics Data System (ADS)

Bosman, Peter A. N.; Alderliesten, Tanja

2016-03-01

We recently demonstrated the strong potential of using dual-dynamic transformation models when tackling deformable image registration problems involving large anatomical differences. Dual-dynamic transformation models employ two moving grids instead of the common single moving grid for the target image (and single fixed grid for the source image). We previously employed powerful optimization algorithms to make use of the additional flexibility offered by a dual-dynamic transformation model with good results, directly obtaining insight into the trade-off between important registration objectives as a result of taking a multi-objective approach to optimization. However, optimization has so far been initialized using two regular grids, which still leaves a great potential of dual-dynamic transformation models untapped: a-priori grid alignment with image structures/areas that are expected to deform more. This allows (far) less grid points to be used, compared to using a sufficiently refined regular grid, leading to (far) more efficient optimization, or, equivalently, more accurate results using the same number of grid points. We study the implications of exploiting this potential by experimenting with two new smart grid initialization procedures: one manual expert-based and one automated image-feature-based. We consider a CT test case with large differences in bladder volume with and without a multi-resolution scheme and find a substantial benefit of using smart grid initialization.

Transport of active ellipsoidal particles in ratchet potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ai, Bao-Quan, E-mail: aibq@scnu.edu.cn; Wu, Jian-Chun

2014-03-07

Rectified transport of active ellipsoidal particles is numerically investigated in a two-dimensional asymmetric potential. The out-of-equilibrium condition for the active particle is an intrinsic property, which can break thermodynamical equilibrium and induce the directed transport. It is found that the perfect sphere particle can facilitate the rectification, while the needlelike particle destroys the directed transport. There exist optimized values of the parameters (the self-propelled velocity, the torque acting on the body) at which the average velocity takes its maximal value. For the ellipsoidal particle with not large asymmetric parameter, the average velocity decreases with increasing the rotational diffusion rate, whilemore » for the needlelike particle (very large asymmetric parameter), the average velocity is a peaked function of the rotational diffusion rate. By introducing a finite load, particles with different shapes (or different self-propelled velocities) will move to the opposite directions, which is able to separate particles of different shapes (or different self-propelled velocities)« less

Access to enhanced differences in Marcus-Hush and Butler-Volmer electron transfer theories by systematic analysis of higher order AC harmonics.

PubMed

Stevenson, Gareth P; Baker, Ruth E; Kennedy, Gareth F; Bond, Alan M; Gavaghan, David J; Gillow, Kathryn

2013-02-14

The potential-dependences of the rate constants associated with heterogeneous electron transfer predicted by the empirically based Butler-Volmer and fundamentally based Marcus-Hush formalisms are well documented for dc cyclic voltammetry. However, differences are often subtle, so, presumably on the basis of simplicity, the Butler-Volmer method is generally employed in theoretical-experimental comparisons. In this study, the ability of Large Amplitude Fourier Transform AC Cyclic Voltammetry to distinguish the difference in behaviour predicted by the two formalisms has been investigated. The focus of this investigation is on the difference in the profiles of the first to sixth harmonics, which are readily accessible when a large amplitude of the applied ac potential is employed. In particular, it is demonstrated that systematic analysis of the higher order harmonic responses in suitable kinetic regimes provides predicted deviations of Marcus-Hush from Butler-Volmer behaviour to be established from a single experiment under conditions where the background charging current is minimal.

Structure of the mouthparts of Frankliniella bispinosa (Morgan) (Thysanoptera: Thripidae)

Treesearch

Carl C. Childers; Diann S. Achor

1991-01-01

Thrips are increasingly recognized as potentially serious pests in a number of different agricultural, ornamental and sylvan commodities worldwide as indicated by the papers presented at this conference. The small size of thrips, their large numbers, capacity for flight and wind dispersal, wide host ranges, poorly understood life histories and probable potential for...

Self-consistent field calculations of conductance through conjugated molecules at finite bias

NASA Astrophysics Data System (ADS)

Paulsson, Magnus; Stafström, Sven

2001-03-01

Conductance through conjugated molecules have previously been calculated for a large number of systems using the Landauer formula but only a few calculations have included charging effects. In this study we present calculations in the mean field approximation of the conductance of metal-molecule-metal systems using two different kinds of molecules for a large number of configurations and applied biases. The molecules are described in the Pariser-Parr Pople model. Current-voltage (I-V) characteristics and charge distribution of the molecule connected by one dimensional leads to reservoirs is solved within the Hartree-Fock approximation. Charging of the molecule occurs when the chemical potential of the reservoirs approach the resonant tunneling levels. The ensuing potential difference, due to the charging, shifts the tunneling peaks which affects the I-V curves considerably. Asymmetrical interaction with the metal leads, e.g. molecule on a metal surface contacted with an STM-tip, also give asymmetrical I-V curves where the potential of the molecule is shown to more closely follow the potential of the surface. Negative differential conductance is discussed in systems consisting of two weakly coupled molecules.

Conifer regeneration in stand-replacement portions of a large mixed-severity wildfire in the Klamath-Siskiyou Mountains

Treesearch

Daniel C. Donato; Joseph B. Fontaine; John L. Campbell; W. Douglas Robinson; J. Boone Kauffman; Beverly E. Law

2009-01-01

Large-scale wildfires (~104-106 ha) have the potential to eliminate seed sources over broad areas and thus may lead to qualitatively different regeneration dynamics than in small burns; however, regeneration after such events has received little study in temperate forests. Following a 200 000 ha mixed-severity...

Lecture Capture Podcasts: Differential Student Use and Performance in a Large Introductory Course

ERIC Educational Resources Information Center

Williams, Adrienne E.; Aguilar-Roca, Nancy M.; O'Dowd, Diane K.

2016-01-01

Video "podcast" recordings of lectures are popular with students, but are often associated with a decrease in attendance and little increase in performance. Assessment has generally focused on the class as a whole, potentially masking benefits to different subgroups. In this study, conducted in 2 sections of a large active-learning…

Perspective on the span-distributed-load concept for application to large cargo aircraft design

NASA Technical Reports Server (NTRS)

Whitehead, A. H., Jr.

1975-01-01

Results of a simplified analysis of the span-distributed-load concept (in which payload is placed within the wing structure) are presented. It is shown that a design based on these principles has a high potential for application to future large air cargo transport. Significant improvements are foreseen in increased payload fraction and productivity and in reduced fuel consumption and operating costs. A review of the efforts in the 1940's to develop all-wing aircraft shows the potential of transferring those early technological developments to current design of distributed-load aircraft. Current market analyses are projected to 1990 to show the future commercial demand for large capacity freighters. Several configuration designs which would serve different market requirements for these large freighters are discussed as are some of the pacing-technology requirements.

Numerical simulation using vorticity-vector potential formulation

NASA Technical Reports Server (NTRS)

Tokunaga, Hiroshi

1993-01-01

An accurate and efficient computational method is needed for three-dimensional incompressible viscous flows in engineering applications. On solving the turbulent shear flows directly or using the subgrid scale model, it is indispensable to resolve the small scale fluid motions as well as the large scale motions. From this point of view, the pseudo-spectral method is used so far as the computational method. However, the finite difference or the finite element methods are widely applied for computing the flow with practical importance since these methods are easily applied to the flows with complex geometric configurations. However, there exist several problems in applying the finite difference method to direct and large eddy simulations. Accuracy is one of most important problems. This point was already addressed by the present author on the direct simulations on the instability of the plane Poiseuille flow and also on the transition to turbulence. In order to obtain high efficiency, the multi-grid Poisson solver is combined with the higher-order, accurate finite difference method. The formulation method is also one of the most important problems in applying the finite difference method to the incompressible turbulent flows. The three-dimensional Navier-Stokes equations have been solved so far in the primitive variables formulation. One of the major difficulties of this method is the rigorous satisfaction of the equation of continuity. In general, the staggered grid is used for the satisfaction of the solenoidal condition for the velocity field at the wall boundary. However, the velocity field satisfies the equation of continuity automatically in the vorticity-vector potential formulation. From this point of view, the vorticity-vector potential method was extended to the generalized coordinate system. In the present article, we adopt the vorticity-vector potential formulation, the generalized coordinate system, and the 4th-order accurate difference method as the computational method. We present the computational method and apply the present method to computations of flows in a square cavity at large Reynolds number in order to investigate its effectiveness.

Bioinformatic Identification of Potential MicroRNAs and Their Targets in the Lingzhi or Reishi Medicinal Mushroom Ganoderma lucidum (Higher Basidiomycetes).

PubMed

Mu, Da-Shuai; Li, Chenyang; Shi, Liang; Zhang, Xuchen; Ren, Ang; Zhao, Ming-Wen

2015-01-01

MicroRNAs (miRNAs) are a class of small, endogenous, noncoding RNA molecules that negatively regulate gene expression at the transcriptional or the post-transcriptional level. Although a large number of miRNAs have been identified in many species, especially model plants and animals, miRNAs in fungi remain largely unknown. In this study, based on a database of expressed sequence tags in Ganoderma lucidum, 89 potential miRNAs were identified using computational methods. Real-time polymerase chain reaction analysis of miRNA-like samples prepared from G. lucidum at different development stages revealed that miRNA-like RNAs were differentially expressed in different stages. Furthermore, a total of 28 potential targets were found based on near-perfect or perfect complementarity between the randomly selected 9 miRNA-like RNAs and the target sequences, and potential targets for G. lucidum miRNA-like RNAs were predicted. Finally, we studied the expression pattern of 4 target genes in 3 different development stages of G. lucidum to further understand the mechanism of interaction between miRNA-like RNAs and their target genes. Our analysis paves the way toward identifying fungal miRNA-like RNAs that might be involved in various physiological and cellular differentiation processes.

Large Nc equivalence and baryons

NASA Astrophysics Data System (ADS)

Blake, Mike; Cherman, Aleksey

2012-09-01

In the large Nc limit, gauge theories with different gauge groups and matter content sometimes turn out to be “large Nc equivalent,” in the sense of having a set of coincident correlation functions. Large Nc equivalence has mainly been explored in the glueball and meson sectors. However, a recent proposal to dodge the fermion sign problem of QCD with a quark number chemical potential using large Nc equivalence motivates investigating the applicability of large Nc equivalence to correlation functions involving baryon operators. Here we present evidence that large Nc equivalence extends to the baryon sector, under the same type of symmetry realization assumptions as in the meson sector, by adapting the classic Witten analysis of large Nc baryons.

Errors in Measuring Water Potentials of Small Samples Resulting from Water Adsorption by Thermocouple Psychrometer Chambers 1

PubMed Central

Bennett, Jerry M.; Cortes, Peter M.

1985-01-01

The adsorption of water by thermocouple psychrometer assemblies is known to cause errors in the determination of water potential. Experiments were conducted to evaluate the effect of sample size and psychrometer chamber volume on measured water potentials of leaf discs, leaf segments, and sodium chloride solutions. Reasonable agreement was found between soybean (Glycine max L. Merr.) leaf water potentials measured on 5-millimeter radius leaf discs and large leaf segments. Results indicated that while errors due to adsorption may be significant when using small volumes of tissue, if sufficient tissue is used the errors are negligible. Because of the relationship between water potential and volume in plant tissue, the errors due to adsorption were larger with turgid tissue. Large psychrometers which were sealed into the sample chamber with latex tubing appeared to adsorb more water than those sealed with flexible plastic tubing. Estimates are provided of the amounts of water adsorbed by two different psychrometer assemblies and the amount of tissue sufficient for accurate measurements of leaf water potential with these assemblies. It is also demonstrated that water adsorption problems may have generated low water potential values which in prior studies have been attributed to large cut surface area to volume ratios. PMID:16664367

Errors in measuring water potentials of small samples resulting from water adsorption by thermocouple psychrometer chambers.

PubMed

Bennett, J M; Cortes, P M

1985-09-01

The adsorption of water by thermocouple psychrometer assemblies is known to cause errors in the determination of water potential. Experiments were conducted to evaluate the effect of sample size and psychrometer chamber volume on measured water potentials of leaf discs, leaf segments, and sodium chloride solutions. Reasonable agreement was found between soybean (Glycine max L. Merr.) leaf water potentials measured on 5-millimeter radius leaf discs and large leaf segments. Results indicated that while errors due to adsorption may be significant when using small volumes of tissue, if sufficient tissue is used the errors are negligible. Because of the relationship between water potential and volume in plant tissue, the errors due to adsorption were larger with turgid tissue. Large psychrometers which were sealed into the sample chamber with latex tubing appeared to adsorb more water than those sealed with flexible plastic tubing. Estimates are provided of the amounts of water adsorbed by two different psychrometer assemblies and the amount of tissue sufficient for accurate measurements of leaf water potential with these assemblies. It is also demonstrated that water adsorption problems may have generated low water potential values which in prior studies have been attributed to large cut surface area to volume ratios.

Invited review: gender issues related to spaceflight: a NASA perspective.

PubMed

Harm, D L; Jennings, R T; Meck, J V; Powell, M R; Putcha, L; Sams, C P; Schneider, S M; Shackelford, L C; Smith, S M; Whitson, P A

2001-11-01

This minireview provides an overview of known and potential gender differences in physiological responses to spaceflight. The paper covers cardiovascular and exercise physiology, barophysiology and decompression sickness, renal stone risk, immunology, neurovestibular and sensorimotor function, nutrition, pharmacotherapeutics, and reproduction. Potential health and functional impacts associated with the various physiological changes during spaceflight are discussed, and areas needing additional research are highlighted. Historically, studies of physiological responses to microgravity have not been aimed at examining gender-specific differences in the astronaut population. Insufficient data exist in most of the discipline areas at this time to draw valid conclusions about gender-specific differences in astronauts, in part due to the small ratio of women to men. The only astronaut health issue for which a large enough data set exists to allow valid conclusions to be drawn about gender differences is orthostatic intolerance following shuttle missions, in which women have a significantly higher incidence of presyncope during stand tests than do men. The most common observation across disciplines is that individual differences in physiological responses within genders are usually as large as, or larger than, differences between genders. Individual characteristics usually outweigh gender differences per se.

Invited review: gender issues related to spaceflight: a NASA perspective

NASA Technical Reports Server (NTRS)

Harm, D. L.; Jennings, R. T.; Meck, J. V.; Powell, M. R.; Putcha, L.; Sams, C. P.; Schneider, S. M.; Shackelford, L. C.; Smith, S. M.; Whitson, P. A.

2001-01-01

This minireview provides an overview of known and potential gender differences in physiological responses to spaceflight. The paper covers cardiovascular and exercise physiology, barophysiology and decompression sickness, renal stone risk, immunology, neurovestibular and sensorimotor function, nutrition, pharmacotherapeutics, and reproduction. Potential health and functional impacts associated with the various physiological changes during spaceflight are discussed, and areas needing additional research are highlighted. Historically, studies of physiological responses to microgravity have not been aimed at examining gender-specific differences in the astronaut population. Insufficient data exist in most of the discipline areas at this time to draw valid conclusions about gender-specific differences in astronauts, in part due to the small ratio of women to men. The only astronaut health issue for which a large enough data set exists to allow valid conclusions to be drawn about gender differences is orthostatic intolerance following shuttle missions, in which women have a significantly higher incidence of presyncope during stand tests than do men. The most common observation across disciplines is that individual differences in physiological responses within genders are usually as large as, or larger than, differences between genders. Individual characteristics usually outweigh gender differences per se.

Large protein as a potential target for use in rabies diagnostics.

PubMed

Santos Katz, I S; Dias, M H; Lima, I F; Chaves, L B; Ribeiro, O G; Scheffer, K C; Iwai, L K

Rabies is a zoonotic viral disease that remains a serious threat to public health worldwide. The rabies lyssavirus (RABV) genome encodes five structural proteins, multifunctional and significant for pathogenicity. The large protein (L) presents well-conserved genomic regions, which may be a good alternative to generate informative datasets for development of new methods for rabies diagnosis. This paper describes the development of a technique for the identification of L protein in several RABV strains from different hosts, demonstrating that MS-based proteomics is a potential method for antigen identification and a good alternative for rabies diagnosis.

The Energy Efficiency Potential of Cloud-Based Software: A U.S. Case Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masanet, Eric; Shehabi, Arman; Liang, Jiaqi

The energy use of data centers is a topic that has received much attention, given that data centers currently account for 1-2% of global electricity use. However, cloud computing holds great potential to reduce data center energy demand moving forward, due to both large reductions in total servers through consolidation and large increases in facility efficiencies compared to traditional local data centers. However, analyzing the net energy implications of shifts to the cloud can be very difficult, because data center services can affect many different components of society’s economic and energy systems.

Simulation of coherent nonlinear neutrino flavor transformation in the supernova environment: Correlated neutrino trajectories

NASA Astrophysics Data System (ADS)

Duan, Huaiyu; Fuller, George M.; Carlson, J.; Qian, Yong-Zhong

2006-11-01

We present results of large-scale numerical simulations of the evolution of neutrino and antineutrino flavors in the region above the late-time post-supernova-explosion proto-neutron star. Our calculations are the first to allow explicit flavor evolution histories on different neutrino trajectories and to self-consistently couple flavor development on these trajectories through forward scattering-induced quantum coupling. Employing the atmospheric-scale neutrino mass-squared difference (|δm2|≃3×10-3eV2) and values of θ13 allowed by current bounds, we find transformation of neutrino and antineutrino flavors over broad ranges of energy and luminosity in roughly the “bi-polar” collective mode. We find that this large-scale flavor conversion, largely driven by the flavor off-diagonal neutrino-neutrino forward scattering potential, sets in much closer to the proto-neutron star than simple estimates based on flavor-diagonal potentials and Mikheyev-Smirnov-Wolfenstein evolution would indicate. In turn, this suggests that models of r-process nucleosynthesis sited in the neutrino-driven wind could be affected substantially by active-active neutrino flavor mixing, even with the small measured neutrino mass-squared differences.

The Potentials of Using Cloud Computing in Schools: A Systematic Literature Review

ERIC Educational Resources Information Center

Hartmann, Simon Birk; Braae, Lotte Qulleq Nygaard; Pedersen, Sine; Khalid, Md. Saifuddin

2017-01-01

Cloud Computing (CC) refers to the physical structure of a communications network, where data is stored in large data centers and can be accessed anywhere, at any time, and from different devices. This systematic literature review identifies and categorizes the potential and barriers of cloud-based teaching in schools from an international…

Different Anaphoric Expressions Are Investigated by Event-Related Brain Potentials

ERIC Educational Resources Information Center

Streb, Judith; Hennighausen, Erwin; Rosler, Frank

2004-01-01

Event-related potentials were recorded to substantiate the claim of a distinct psycholinguistic status of (a) pronouns vs. proper names and (b) ellipses vs. proper names. In two studies 41 students read sentences in which the number of intervening words between the anaphor and its antecedent was either small or large. Comparing the far with the…

Flow adjustment inside large finite-size wind farms approaching the infinite wind farm regime

NASA Astrophysics Data System (ADS)

Wu, Ka Ling; Porté-Agel, Fernando

2017-04-01

Due to the increasing number and the growing size of wind farms, the distance among them continues to decrease. Thus, it is necessary to understand how these large finite-size wind farms and their wakes could interfere the atmospheric boundary layer (ABL) dynamics and adjacent wind farms. Fully-developed flow inside wind farms has been extensively studied through numerical simulations of infinite wind farms. The transportation of momentum and energy is only vertical and the advection of them is neglected in these infinite wind farms. However, less attention has been paid to examine the length of wind farms required to reach such asymptotic regime and the ABL dynamics in the leading and trailing edges of the large finite-size wind farms. Large eddy simulations are performed in this study to investigate the flow adjustment inside large finite-size wind farms in conventionally-neutral boundary layer with the effect of Coriolis force and free-atmosphere stratification from 1 to 5 K/km. For the large finite-size wind farms considered in the present work, when the potential temperature lapse rate is 5 K/km, the wind farms exceed the height of the ABL by two orders of magnitude for the incoming flow inside the farms to approach the fully-developed regime. An entrance fetch of approximately 40 times of the ABL height is also required for such flow adjustment. At the fully-developed flow regime of the large finite-size wind farms, the flow characteristics match those of infinite wind farms even though they have different adjustment length scales. The role of advection at the entrance and exit regions of the large finite-size wind farms is also examined. The interaction between the internal boundary layer developed above the large finite-size wind farms and the ABL under different potential temperature lapse rates are compared. It is shown that the potential temperature lapse rate plays a role in whether the flow inside the large finite-size wind farms adjusts to the fully-developed flow regime. The flow characteristics of the wake of these large finite-size wind farms are reported to forecast the effect of large finite-size wind farms on adjacent wind farms. A power deficit as large as 8% is found at a distance of 10 km downwind from the large finite-size wind farms.

Playing to Teachers' Strengths: Using Multiple Measures of Teacher Effectiveness to Improve Teacher Assignments

ERIC Educational Resources Information Center

Fox, Lindsay

2016-01-01

Current uses of value-added modeling largely ignore or assume away the potential for teachers to be more effective with one type of student than another or in one subject than another. This paper explores the stability of value-added measures across different subgroups and subjects using administrative data from a large urban school district. For…

(Re)Telling Lived Experiences in Different Tales: A Potential Pathway in Working towards an Inclusive PE

ERIC Educational Resources Information Center

Berg Svendby, Ellen

2016-01-01

Existing research reveals that there are large discrepancies between the rhetoric of inclusive practice and what actually takes place in physical education (PE) lessons. PE appears to be a conservative subject, where little has changed over the years, despite increased diversity in schools and new modes of movement in society at large. In this…

Molecular versus squared Woods-Saxon α-nucleus potentials in the 27Al(α, t)28Si reaction

NASA Astrophysics Data System (ADS)

Abdullah, M. N. A.; Das, S. K.; Tariq, A. S. B.; Mahbub, M. S.; Mondal, A. S.; Uddin, M. A.; Basak, A. K.; Gupta, H. M. Sen; Malik, F. B.

2003-06-01

The differential cross-section of the 27Al(alpha, t)28Si reaction for 64.5 MeV incident energy has been reanalysed in DWBA with full finite range using a squared Woods-Saxon (Michel) alpha-nucleus potential with the modified value of the depth parameter alpha = 2.0 as reported in a comment article by Michel and Reidemeister. This new value produces significant improvement in fitting the data of the reaction with its overall performance, in some cases, close to that previously observed for the molecular potential. Although the non-monotonic shallow molecular potential with a soft repulsive core and the Michel potentials produce the same quality fits to the elastic scattering and non-elastic processes, they are not phase equivalent. The two types of potential produce altogether different cross-sections, particularly at large reaction angles. The importance of the experimental cross-sections at large angles for both elastic scattering and non-elastic processes is elucidated.

Effects of Muscle Atrophy on Motor Control: Cage-size Effects

NASA Technical Reports Server (NTRS)

Stuart, D. G.

1985-01-01

Two populations of male Sprague-Dawley rats were raised either in conventional minimum-specification cages or in a larger cage. When the animals were mature (125 to 150 d), the physiological status of the soleus (SOL) and extensor digitorum longus (EDL) muscles of the small- and large-cage animals were compared. Analysis of whole-muscle properties including the performance of the test muscle during a standardized fatigue test in which the nerve to the test muscle was subjected to supramaximal intermittent stimulation shows: (1) the amplitude, area, mean amplitude, and peak-to-peak rate of the compound muscle action potential decreased per the course of the fatigue test; (2) cage size did not affect the profile of changes for any of the action-potential measurements; (3) changes exhibited in the compound muscle action potential by SOL and EDL were substantially different; and (4) except for SOL of the large-cage rats, there was a high correlation between all four measures of the compound muscle action potential and the peak tetanic force during the fatigue test; i.e., either the electrical activity largely etermines the force profile during the fatigue test or else contractile-related activity substantially affects the compound muscle action potential.

Affective traits link to reliable neural markers of incentive anticipation.

PubMed

Wu, Charlene C; Samanez-Larkin, Gregory R; Katovich, Kiefer; Knutson, Brian

2014-01-01

While theorists have speculated that different affective traits are linked to reliable brain activity during anticipation of gains and losses, few have directly tested this prediction. We examined these associations in a community sample of healthy human adults (n=52) as they played a Monetary Incentive Delay task while undergoing functional magnetic resonance imaging (FMRI). Factor analysis of personality measures revealed that subjects independently varied in trait Positive Arousal and trait Negative Arousal. In a subsample (n=14) retested over 2.5years later, left nucleus accumbens (NAcc) activity during anticipation of large gains (+$5.00) and right anterior insula activity during anticipation of large losses (-$5.00) showed significant test-retest reliability (intraclass correlations>0.50, p's<0.01). In the full sample (n=52), trait Positive Arousal correlated with individual differences in left NAcc activity during anticipation of large gains, while trait Negative Arousal correlated with individual differences in right anterior insula activity during anticipation of large losses. Associations of affective traits with neural activity were not attributable to the influence of other potential confounds (including sex, age, wealth, and motion). Together, these results demonstrate selective links between distinct affective traits and reliably-elicited activity in neural circuits associated with anticipation of gain versus loss. The findings thus reveal neural markers for affective dimensions of healthy personality, and potentially for related psychiatric symptoms. © 2013. Published by Elsevier Inc. All rights reserved.

Affective traits link to reliable neural markers of incentive anticipation

PubMed Central

Wu, Charlene C.; Samanez-Larkin, Gregory R.; Katovich, Kiefer; Knutson, Brian

2013-01-01

While theorists have speculated that different affective traits are linked to reliable brain activity during anticipation of gains and losses, few have directly tested this prediction. We examined these associations in a community sample of healthy human adults (n = 52) as they played a Monetary Incentive Delay Task while undergoing functional magnetic resonance imaging (FMRI). Factor analysis of personality measures revealed that subjects independently varied in trait Positive Arousal and Negative Arousal. In a subsample (n = 14) retested over 2.5 years later, left nucleus accumbens (NAcc) activity during anticipation of large gains (+$5.00) and right anterior insula activity during anticipation of large losses (−$5.00) showed significant test-retest reliability (intraclass correlations > 0.50, p’s < 0.01). In the full sample (n = 52), trait Positive Arousal correlated with individual differences in left NAcc activity during anticipation of large gains, while trait Negative Arousal correlated with individual differences in right anterior insula activity during anticipation of large losses. Associations of affective traits with neural activity were not attributable to the influence of other potential confounds (including sex, age, wealth, and motion). Together, these results demonstrate selective links between distinct affective traits and reliably-elicited activity in neural circuits associated with anticipation of gain versus loss. The findings thus reveal neural markers for affective dimensions of healthy personality, and potentially for related psychiatric symptoms. PMID:24001457

Particulate matter emissions from biochar-amended soils as a potential tradeoff to the negative emission potential

NASA Astrophysics Data System (ADS)

Ravi, Sujith; Sharratt, Brenton S.; Li, Junran; Olshevski, Stuart; Meng, Zhongju; Zhang, Jianguo

2016-10-01

Novel carbon sequestration strategies such as large-scale land application of biochar may provide sustainable pathways to increase the terrestrial storage of carbon. Biochar has a long residence time in the soil and hence comprehensive studies are urgently needed to quantify the environmental impacts of large-scale biochar application. In particular, black carbon emissions from soils amended with biochar may counteract the negative emission potential due to the impacts on air quality, climate, and biogeochemical cycles. We investigated, using wind tunnel experiments, the particulate matter emission potential of a sand and two agriculturally important soils amended with different concentrations of biochar, in comparison to control soils. Our results indicate that biochar application considerably increases particulate emissions possibly by two mechanisms-the accelerated emission of fine biochar particles and the generation and emission of fine biochar particles resulting from abrasion of large biochar particles by sand grains. Our study highlights the importance of considering the background soil properties (e.g., texture) and geomorphological processes (e.g., aeolian transport) for biochar-based carbon sequestration programs.

Tachyon inflation in the large-N formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbosa-Cendejas, Nandinii; De-Santiago, Josue; German, Gabriel

2015-11-01

We study tachyon inflation within the large-N formalism, which takes a prescription for the small Hubble flow slow-roll parameter ε{sub 1} as a function of the large number of e-folds N. This leads to a classification of models through their behaviour at large N. In addition to the perturbative N class, we introduce the polynomial and exponential classes for the ε{sub 1} parameter. With this formalism we reconstruct a large number of potentials used previously in the literature for tachyon inflation. We also obtain new families of potentials from the polynomial class. We characterize the realizations of tachyon inflation bymore » computing the usual cosmological observables up to second order in the Hubble flow slow-roll parameters. This allows us to look at observable differences between tachyon and canonical single field inflation. The analysis of observables in light of the Planck 2015 data shows the viability of some of these models, mostly for certain realization of the polynomial and exponential classes.« less

Flexible Redistribution in Cognitive Networks.

PubMed

Hartwigsen, Gesa

2018-06-15

Previous work has emphasized that cognitive functions in the human brain are organized into large-scale networks. However, the mechanisms that allow these networks to compensate for focal disruptions remain elusive. I suggest a new perspective on the compensatory flexibility of cognitive networks. First, I demonstrate that cognitive networks can rapidly change the functional weight of the relative contribution of different regions. Second, I argue that there is an asymmetry in the compensatory potential of different kinds of networks. Specifically, recruitment of domain-general functions can partially compensate for focal disruptions of specialized cognitive functions, but not vice versa. Considering the compensatory potential within and across networks will increase our understanding of functional adaptation and reorganization after brain lesions and offers a new perspective on large-scale neural network (re-)organization. Copyright © 2018 Elsevier Ltd. All rights reserved.

Finite-difference computations of rotor loads

NASA Technical Reports Server (NTRS)

Caradonna, F. X.; Tung, C.

1985-01-01

This paper demonstrates the current and future potential of finite-difference methods for solving real rotor problems which now rely largely on empiricism. The demonstration consists of a simple means of combining existing finite-difference, integral, and comprehensive loads codes to predict real transonic rotor flows. These computations are performed for hover and high-advance-ratio flight. Comparisons are made with experimental pressure data.

Finite-difference computations of rotor loads

NASA Technical Reports Server (NTRS)

Caradonna, F. X.; Tung, C.

1985-01-01

The current and future potential of finite difference methods for solving real rotor problems which now rely largely on empiricism are demonstrated. The demonstration consists of a simple means of combining existing finite-difference, integral, and comprehensive loads codes to predict real transonic rotor flows. These computations are performed for hover and high-advanced-ratio flight. Comparisons are made with experimental pressure data.

Sex Differences on "g" and Non-"g" Intellectual Performance Reveal Potential Sources of STEM Discrepancies

ERIC Educational Resources Information Center

Lemos, Gina C.; Abad, Francisco J.; Almeida, Leandro S.; Colom, Roberto

2013-01-01

The analysis of sex differences in cognitive abilities is largely confusing because these differences are masked by the pervasive influence of the general factor of intelligence (g). In this study a battery of five reasoning tests (abstract [AR], numerical [NR], verbal [VR], mechanical [MR], and spatial [SR]) was completed by a sample of 3233…

A Review of Sex Differences in Peer Relationship Processes: Potential Trade-Offs for the Emotional and Behavioral Development of Girls and Boys

ERIC Educational Resources Information Center

Rose, Amanda J.; Rudolph, Karen D.

2006-01-01

Theory and research on sex differences in adjustment focus largely on parental, societal, and biological influences. However, it also is important to consider how peers contribute to girls' and boys' development. This article provides a critical review of sex differences in several peer relationship processes, including behavioral and…

ATP is released from rabbit urinary bladder epithelial cells by hydrostatic pressure changes--a possible sensory mechanism?

PubMed Central

Ferguson, D R; Kennedy, I; Burton, T J

1997-01-01

1. The responses of rabbit urinary bladder to hydrostatic pressure changes and to electrical stimulation have been investigated using both the Ussing chamber and a superfusion apparatus. These experiments enabled us to monitor changes in both ionic transport across the tissue and cellular ATP release from it. 2. The urinary bladder of the rabbit maintains an electrical potential difference across its wall as a result largely of active sodium transport from the urinary (mucosal) to the serosal surface. 3. Small hydrostatic pressure differences produced by removal of bathing fluid from one side of the tissue caused reproducible changes in both potential difference and short-circuit current. The magnitude of these changes increases as the volume of fluid removed increases. 3. Amiloride on the mucosal (urinary), but not the serosal, surface of the membrane reduces the transepithelial potential difference and short-circuit current with an IC50 of 300 nM. Amiloride reduces the size of, but does not abolish, transepithelial potential changes caused by alterations in hydrostatic pressure. 4. Field electrical stimulation of strips of bladder tissue produces a reproducible release of ATP. Such release was demonstrated to occur largely from urothelial cells and is apparently non-vesicular as it increases in the absence of calcium and is not abolished by tetrodotoxin. 5. It is proposed that ATP is released from the urothelium as a sensory mediator for the degree of distension of the rabbit urinary bladder and other sensory modalities. PMID:9423189

EMI from Spacecraft Docking Systems Spacecraft Charging - Plasma Contact Potentials

NASA Technical Reports Server (NTRS)

Norgard, John D.; Scully, Robert; Musselman, Randall

2012-01-01

The plasma contact potential of a visiting vehicle (VV), such as the Orion Service Module (SM), is determined while docking at the Orion Crew Exploration Vehicle (CEV). Due to spacecraft charging effects on-orbit, the potential difference between the CEV and the VV can be large at docking, and an electrostatic discharge (ESD) could occur at capture, which could degrade, disrupt, damage, or destroy sensitive electronic equipment on the CEV and/or VV. Analytical and numerical models of the CEV are simulated to predict the worst-case potential difference between the CEV and the VV when the CEV is unbiased (solar panels unlit: eclipsed in the dark and inactive) or biased (solar panels sunlit: in the light and active).

Reproductive potential of Spodoptera eridania (Stoll) (Lepidoptera: Noctuidae) in the laboratory: effect of multiple couples and the size.

PubMed

Specht, A; Montezano, D G; Sosa-Gómez, D R; Paula-Moraes, S V; Roque-Specht, V F; Barros, N M

2016-06-01

This study aimed to evaluate the effect of keeping three couples in the same cage, and the size of adults emerged from small, medium-sized and large pupae (278.67 mg; 333.20 mg and 381.58 mg, respectively), on the reproductive potential of S. eridania (Stoll, 1782) adults, under controlled conditions (25 ± 1 °C, 70% RH and 14 hour photophase). We evaluated the survival, number of copulations, fecundity and fertility of the adult females. The survival of females from these different pupal sizes did not differ statistically, but the survival of males from large pupae was statistically shorter than from small pupae. Fecundity differed significantly and correlated positively with size. The number of effective copulations (espematophores) and fertility did not vary significantly with pupal size. Our results emphasize the importance of indicating the number of copulations and the size of the insects when reproductive parameters are compared.

Potential genotoxic effects of melted snow from an urban area revealed by the Allium cepa test.

PubMed

Blagojević, Jelena; Stamenković, Gorana; Vujosević, Mladen

2009-09-01

The presence of well-known atmospheric pollutants is regularly screened for in large towns but knowledge about the effects of mixtures of different pollutants and especially their genotoxic potential is largely missing. Since falling snow collects pollutants from the air, melted snow samples could be suitable for evaluating potential genotoxicity. For this purpose the Allium cepa anaphase-telophase test was used to analyse melted snow samples from Belgrade, the capital city of Serbia. Samples of snow were taken at two sites, characterized by differences in pollution intensity, in three successive years. At the more polluted site the analyses showed a very high degree of both toxicity and genotoxicity in the first year of the study corresponding to the effects of the known mutagen used as the positive control. At the other site the situation was much better but not without warning signals. The results showed that standard analyses for the presence of certain contaminants in the air do not give an accurate picture of the possible consequences of urban air pollution because the genotoxic potential remains hidden. The A. cepa test has been demonstrated to be very convenient for evaluation of air pollution through analyses of melted snow samples.

Changes in extremes due to half a degree warming in observations and models

NASA Astrophysics Data System (ADS)

Fischer, E. M.; Schleussner, C. F.; Pfleiderer, P.

2017-12-01

Assessing the climate impacts of half-a-degree warming increments is high on the post-Paris science agenda. Discriminating those effects is particularly challenging for climate extremes such as heavy precipitation and heat extremes for which model uncertainties are generally large, and for which internal variability is so important that it can easily offset or strongly amplify the forced local changes induced by half a degree warming. Despite these challenges we provide evidence for large-scale changes in the intensity and frequency of climate extremes due to half a degree warming. We first assess the difference in extreme climate indicators in observational data for the 1960s and 1970s versus the recent past, two periods differ by half a degree. We identify distinct differences for the global and continental-scale occurrence of heat and heavy precipitation extremes. We show that those observed changes in heavy precipitation and heat extremes broadly agree with simulated historical differences and are informative for the projected differences between 1.5 and 2°C warming despite different radiative forcings. We therefore argue that evidence from the observational record can inform the debate about discernible climate impacts in the light of model uncertainty by providing a conservative estimate of the implications of 0.5°C warming. A limitation of using the observational record arises from potential non-linearities in the response of climate extremes to a certain level of warming. We test for potential non-linearities in the response of heat and heavy precipitation extremes in a large ensemble of transient climate simulations. We further quantify differences between a time-window approach in a coupled model large ensemble vs. time-slice experiments using prescribed SST experiments performed in the context of the HAPPI-MIP project. Thereby we provide different lines of evidence that half a degree warming leads to substantial changes in the expected occurrence of heat and heavy precipitation extremes.

Evaluation of biochar powder on oxygen supply efficiency and global warming potential during mainstream large-scale aerobic composting.

PubMed

He, Xueqin; Chen, Longjian; Han, Lujia; Liu, Ning; Cui, Ruxiu; Yin, Hongjie; Huang, Guangqun

2017-12-01

This study investigated the effects of biochar powder on oxygen supply efficiency and global warming potential (GWP) in the large-scale aerobic composting pattern which includes cyclical forced-turning with aeration at the bottom of composting tanks in China. A 55-day large-scale aerobic composting experiment was conducted in two different groups without and with 10% biochar powder addition (by weight). The results show that biochar powder improves the holding ability of oxygen, and the duration time (O 2 >5%) is around 80%. The composting process with above pattern significantly reduce CH 4 and N 2 O emissions compared to the static or turning-only styles. Considering the average GWP of the BC group was 19.82% lower than that of the CK group, it suggests that rational addition of biochar powder has the potential to reduce the energy consumption of turning, improve effectiveness of the oxygen supply, and reduce comprehensive greenhouse effects. Copyright © 2017. Published by Elsevier Ltd.

Effect of plasma grid bias on extracted currents in the RF driven surface-plasma negative ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belchenko, Yu., E-mail: belchenko@inp.nsk.su; Ivanov, A.; Sanin, A.

2016-02-15

Extraction of negative ions from the large inductively driven surface-plasma negative ion source was studied. The dependencies of the extracted currents vs plasma grid (PG) bias potential were measured for two modifications of radio-frequency driver with and without Faraday screen, for different hydrogen feeds and for different levels of cesium conditioning. The maximal PG current was independent of driver modification and it was lower in the case of inhibited cesium. The maximal extracted negative ion current depends on the potential difference between the near-PG plasma and the PG bias potentials, while the absolute value of plasma potential in the drivermore » and in the PG area is less important for the negative ion production. The last conclusion confirms the main mechanism of negative ion production through the surface conversion of fast atoms.« less

Simple tool for the rapid, automated quantification of glacier advance/retreat observations using multiple methods

NASA Astrophysics Data System (ADS)

Lea, J.

2017-12-01

The quantification of glacier change is a key variable within glacier monitoring, with the method used potentially being crucial to ensuring that data can be appropriately compared with environmental data. The topic and timescales of study (e.g. land/marine terminating environments; sub-annual/decadal/centennial/millennial timescales) often mean that different methods are more suitable for different problems. However, depending on the GIS/coding expertise of the user, some methods can potentially be time consuming to undertake, making large-scale studies problematic. In addition, examples exist where different users have nominally applied the same methods in different studies, though with minor methodological inconsistencies in their approach. In turn, this will have implications for data homogeneity where regional/global datasets may be constructed. Here, I present a simple toolbox scripted in a Matlab® environment that requires only glacier margin and glacier centreline data to quantify glacier length, glacier change between observations, rate of change, in addition to other metrics. The toolbox includes the option to apply the established centreline or curvilinear box methods, or a new method: the variable box method - designed for tidewater margins where box width is defined as the total width of the individual terminus observation. The toolbox is extremely flexible, and has the option to be applied as either Matlab® functions within user scripts, or via a graphical user interface (GUI) for those unfamiliar with a coding environment. In both instances, there is potential to apply the methods quickly to large datasets (100s-1000s of glaciers, with potentially similar numbers of observations each), thus ensuring large scale methodological consistency (and therefore data homogeneity) and allowing regional/global scale analyses to be achievable for those with limited GIS/coding experience. The toolbox has been evaluated against idealised scenarios demonstrating its accuracy, while feedback from undergraduate students who have trialled the toolbox is that it is intuitive and simple to use. When released, the toolbox will be free and open source allowing users to potentially modify, improve and expand upon the current version.

Adsorption differences between low coverage enantiomers of alanine on the chiral Cu{421}R surface.

PubMed

Gladys, Michael J; Han, Jeong Woo; Pedersen, Therese S; Tadich, Anton; O'Donnell, Kane M; Thomsen, Lars

2017-05-31

Chiral separation using heterogeneous methods has long been sought after. Chiral metal surfaces have the potential to make it possible to model these systems using small amino acids, the building blocks for proteins. A comparison of submonolayer concentrations of alanine enantiomers adsorbed onto Cu{421} R has revealed a large geometrical differences between the two molecules as compared to the saturated coverage. Large differences were observed in HR-XPS and NEXAFS and complemented by theoretical DFT calculations. At approximately one third of a monolayer a comparison of the C1s XPS signal showed a shift in the methyl group of more than 300 meV indicating that the two enantiomers are in different chemical environments. NEXAFS spectroscopy confirmed the XPS variations and showed large differences in the orientation of the adsorbed molecules. Our DFT results show that the l-enantiomer is energetically the most stable in the {311} microfacet configuration. In contrast to the full monolayer coverage, these lower coverages showed enhanced selectivity.

Potential groundwater recharge for the State of Minnesota using the Soil-Water-Balance model, 1996-2010

USGS Publications Warehouse

Smith, Erik A.; Westenbroek, Stephen M.

2015-01-01

On an annual basis, however, potential recharge rates were as high as 27.2 inches per year. The highest annual mean recharge estimate across the State was for 2010, and the lowest mean recharge estimate was for 2003. Although precipitation variability partially explained the annual differences in potential recharge estimates, precipitation alone did not account for these differences, and other factors such as antecedent moisture conditions likely were important. Also, because precipitation gradients across the State can vary from year to year, the dominant land-cover class and hydrologic soil group combinations for a particular region had a large effect on the resulting potential recharge value. During 1996–2010, April had the greatest monthly mean potential recharge compared to all other months, accounting for a mean of 30 percent of annual potential recharge in this single month.

Effects of seed predators of different body size on seed mortality in Bornean logged forest.

PubMed

Hautier, Yann; Saner, Philippe; Philipson, Christopher; Bagchi, Robert; Ong, Robert C; Hector, Andy

2010-07-19

The Janzen-Connell hypothesis proposes that seed and seedling enemies play a major role in maintaining high levels of tree diversity in tropical forests. However, human disturbance may alter guilds of seed predators including their body size distribution. These changes have the potential to affect seedling survival in logged forest and may alter forest composition and diversity. We manipulated seed density in plots beneath con- and heterospecific adult trees within a logged forest and excluded vertebrate predators of different body sizes using cages. We show that small and large-bodied predators differed in their effect on con- and heterospecific seedling mortality. In combination small and large-bodied predators dramatically decreased both con- and heterospecific seedling survival. In contrast, when larger-bodied predators were excluded small-bodied predators reduced conspecific seed survival leaving seeds coming from the distant tree of a different species. Our results suggest that seed survival is affected differently by vertebrate predators according to their body size. Therefore, changes in the body size structure of the seed predator community in logged forests may change patterns of seed mortality and potentially affect recruitment and community composition.

Effects of Seed Predators of Different Body Size on Seed Mortality in Bornean Logged Forest

PubMed Central

Hautier, Yann; Saner, Philippe; Philipson, Christopher; Bagchi, Robert; Ong, Robert C.; Hector, Andy

2010-01-01

Background The Janzen-Connell hypothesis proposes that seed and seedling enemies play a major role in maintaining high levels of tree diversity in tropical forests. However, human disturbance may alter guilds of seed predators including their body size distribution. These changes have the potential to affect seedling survival in logged forest and may alter forest composition and diversity. Methodology/Principal Findings We manipulated seed density in plots beneath con- and heterospecific adult trees within a logged forest and excluded vertebrate predators of different body sizes using cages. We show that small and large-bodied predators differed in their effect on con- and heterospecific seedling mortality. In combination small and large-bodied predators dramatically decreased both con- and heterospecific seedling survival. In contrast, when larger-bodied predators were excluded small-bodied predators reduced conspecific seed survival leaving seeds coming from the distant tree of a different species. Conclusions/Significance Our results suggest that seed survival is affected differently by vertebrate predators according to their body size. Therefore, changes in the body size structure of the seed predator community in logged forests may change patterns of seed mortality and potentially affect recruitment and community composition. PMID:20657841

Many-particle-effects in the theory of the extended X-ray absorption fine structure

NASA Astrophysics Data System (ADS)

Tran Thoai, D. B.; Ekardt, W.

1981-10-01

The Lee-Beni-procedure for the calculation of the extended X-ray absorption fine structure (EXAFS) is extended so as to include the effects of the electronic charge density outside the localized muffin-tin potentials. In our scheme EXAFS is caused by back-scattering of an elementary excitation of a homogeneous electron gas by localized energy dependent many-particle muffin-tin potentials. The difference between the two schemes is negligible at large k's, as expected from physical grounds. However, at small and intermediate k-values the difference is quite large. The effect of the outer electrons as compared to the Lee-Beni-model is twofold. First, they renormalize the scattered electron in the usual way. Second, they are missing within the scattering muffin-tins. Hence, we avoid to count some of the electrons twice. Results are presented for Cu as an example.

The site-scale saturated zone flow model for Yucca Mountain: Calibration of different conceptual models and their impact on flow paths

USGS Publications Warehouse

Zyvoloski, G.; Kwicklis, E.; Eddebbarh, A.-A.; Arnold, B.; Faunt, C.; Robinson, B.A.

2003-01-01

This paper presents several different conceptual models of the Large Hydraulic Gradient (LHG) region north of Yucca Mountain and describes the impact of those models on groundwater flow near the potential high-level repository site. The results are based on a numerical model of site-scale saturated zone beneath Yucca Mountain. This model is used for performance assessment predictions of radionuclide transport and to guide future data collection and modeling activities. The numerical model is calibrated by matching available water level measurements using parameter estimation techniques, along with more informal comparisons of the model to hydrologic and geochemical information. The model software (hydrologic simulation code FEHM and parameter estimation software PEST) and model setup allows for efficient calibration of multiple conceptual models. Until now, the Large Hydraulic Gradient has been simulated using a low-permeability, east-west oriented feature, even though direct evidence for this feature is lacking. In addition to this model, we investigate and calibrate three additional conceptual models of the Large Hydraulic Gradient, all of which are based on a presumed zone of hydrothermal chemical alteration north of Yucca Mountain. After examining the heads and permeabilities obtained from the calibrated models, we present particle pathways from the potential repository that record differences in the predicted groundwater flow regime. The results show that Large Hydraulic Gradient can be represented with the alternate conceptual models that include the hydrothermally altered zone. The predicted pathways are mildly sensitive to the choice of the conceptual model and more sensitive to the quality of calibration in the vicinity on the repository. These differences are most likely due to different degrees of fit of model to data, and do not represent important differences in hydrologic conditions for the different conceptual models. ?? 2002 Elsevier Science B.V. All rights reserved.

Positive Affect Processing and Joint Attention in Infants at High Risk for Autism: An Exploratory Study

ERIC Educational Resources Information Center

Key, Alexandra P.; Ibanez, Lisa V.; Henderson, Heather A.; Warren, Zachary; Messinger, Daniel S.; Stone, Wendy L.

2015-01-01

Few behavioral indices of risk for autism spectrum disorders (ASD) are present before 12 months, and potential biomarkers remain largely unexamined. This prospective study of infant siblings of children with ASD (n = 16) and low-risk comparison infants (n = 15) examined group differences in event-related potentials (ERPs) indexing processing of…

Entropic potential field formed for a linear-motor protein near a filament: Statistical-mechanical analyses using simple models.

PubMed

Amano, Ken-Ichi; Yoshidome, Takashi; Iwaki, Mitsuhiro; Suzuki, Makoto; Kinoshita, Masahiro

2010-07-28

We report a new progress in elucidating the mechanism of the unidirectional movement of a linear-motor protein (e.g., myosin) along a filament (e.g., F-actin). The basic concept emphasized here is that a potential field is entropically formed for the protein on the filament immersed in solvent due to the effect of the translational displacement of solvent molecules. The entropic potential field is strongly dependent on geometric features of the protein and the filament, their overall shapes as well as details of the polyatomic structures. The features and the corresponding field are judiciously adjusted by the binding of adenosine triphosphate (ATP) to the protein, hydrolysis of ATP into adenosine diphosphate (ADP)+Pi, and release of Pi and ADP. As the first step, we propose the following physical picture: The potential field formed along the filament for the protein without the binding of ATP or ADP+Pi to it is largely different from that for the protein with the binding, and the directed movement is realized by repeated switches from one of the fields to the other. To illustrate the picture, we analyze the spatial distribution of the entropic potential between a large solute and a large body using the three-dimensional integral equation theory. The solute is modeled as a large hard sphere. Two model filaments are considered as the body: model 1 is a set of one-dimensionally connected large hard spheres and model 2 is a double helical structure formed by two sets of connected large hard spheres. The solute and the filament are immersed in small hard spheres forming the solvent. The major findings are as follows. The solute is strongly confined within a narrow space in contact with the filament. Within the space there are locations with sharply deep local potential minima along the filament, and the distance between two adjacent locations is equal to the diameter of the large spheres constituting the filament. The potential minima form a ringlike domain in model 1 while they form a pointlike one in model 2. We then examine the effects of geometric features of the solute on the amplitudes and asymmetry of the entropic potential field acting on the solute along the filament. A large aspherical solute with a cleft near the solute-filament interface, which mimics the myosin motor domain, is considered in the examination. Thus, the two fields in our physical picture described above are qualitatively reproduced. The factors to be taken into account in further studies are also discussed.

Equilibrium Structures and Absorption Spectra for SixOy Molecular Clusters using Density Functional Theory

DTIC Science & Technology

2017-05-05

dependent density functional theory (TD-DFT). The size of the clusters considered is relatively large compared to those considered in previous studies...are characterized by many different geometries, which potentially can be optimized with respect to specific materials design criteria, i.e., molecular...SixOy molecular clusters using density functional theory (DFT). The size of the clusters considered, however, is relatively large compared to those

Socio-Economic Status and Early Childhood Cognitive Skills: A Mediation Analysis Using the Young Lives Panel

ERIC Educational Resources Information Center

Lopez Boo, Florencia

2016-01-01

This article documents differences in cognitive development, as measured by the Peabody Picture Vocabulary Test (PPVT), between children from households with high and low socioeconomic status (SES) in two different phases of early childhood in four developing countries. A large number of potential mediators, such as urban residence, preschool…

Explanatory Item Response Modeling of Children's Change on a Dynamic Test of Analogical Reasoning

ERIC Educational Resources Information Center

Stevenson, Claire E.; Hickendorff, Marian; Resing, Wilma C. M.; Heiser, Willem J.; de Boeck, Paul A. L.

2013-01-01

Dynamic testing is an assessment method in which training is incorporated into the procedure with the aim of gauging cognitive potential. Large individual differences are present in children's ability to profit from training in analogical reasoning. The aim of this experiment was to investigate sources of these differences on a dynamic test of…

Redox equilibria in hydroxylamine oxidoreductase. Electrostatic control of electron redistribution in multielectron oxidative processes.

PubMed

Kurnikov, Igor V; Ratner, Mark A; Pacheco, A Andrew

2005-02-15

We report results of continuum electrostatics calculations of the cofactor redox potentials, and of the titratable group pK(a) values, in hydroxylamine oxidoreductase (HAO). A picture of a sophisticated multicomponent control of electron flow in the protein emerged from the studies. First, we found that neighboring heme cofactors strongly interact electrostatically, with energies of 50-100 mV. Thus, cofactor redox potentials depend on the oxidation state of other cofactors, and cofactor redox potentials in the active (partially oxidized) enzyme differ substantially from the values obtained in electrochemical redox titration experiments. We found that, together, solvent-exposed heme 1 (having a large negative redox potential) and heme 2 (having a large positive redox potential) form a lock for electrons generated during the oxidation reaction The attachment of HAO's physiological electron transfer partner cytochrome c(554) results in a positive shift in the redox potential of heme 1, and "opens the electron gate". Electrons generated as a result of hydroxylamine oxidation travel to heme 3 and heme 8, which have redox potentials close to 0 mV versus NHE (this result is in partial disagreement with an existing experimental redox potential assignment). The closeness of hemes 3 and 8 from different enzyme subunits allows redistribution of the four electrons generated as a result of hydroxylamine oxidation, among the three enzyme subunits. For the multielectron oxidation process to be maximally efficient, the redox potentials of the electron-accepting cofactors should be roughly equal, and electrostatic interactions between extra electrons on these cofactors should be minimal. The redox potential assignments presented in the paper satisfy this general rule.

Possible higher order phase transition in large-N gauge theory at finite temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishimura, Hiromichi

2017-08-07

We analyze the phase structure of SU(¥) gauge theory at finite temperature using matrix models. Our basic assumption is that the effective potential is dominated by double-trace terms for the Polyakov loops. As a function of the temperature, a background field for the Polyakov loop, and a quartic coupling, it exhibits a universal structure: in the large portion of the parameter space, there is a continuous phase transition analogous to the third-order phase transition of Gross,Witten and Wadia, but the order of phase transition can be higher than third. We show that different confining potentials give rise to drastically differentmore » behavior of the eigenvalue density and the free energy. Therefore lattice simulations at large N could probe the order of phase transition and test our results. Critical« less

Energy spectra of small bosonic clusters having a large two-body scattering length

NASA Astrophysics Data System (ADS)

Gattobigio, M.; Kievsky, A.; Viviani, M.

2012-10-01

In this work we investigate small clusters of bosons using the hyperspherical harmonic basis. We consider systems with A=2,3,4,5,6 particles interacting through a soft interparticle potential. In order to make contact with a real system, we use an attractive Gaussian potential that reproduces the values of the dimer binding energy and the atom-atom scattering length obtained with one of the most widely used 4He-4He interactions, the LM2M2 potential of Aziz and Slaman. The intensity of the potential is varied in order to explore the clusters’ spectra in different regions with large positive and large negative values of the two-body scattering length. In addition, we include a repulsive three-body force to reproduce the trimer binding energy. With this model, consisting in the sum of a two- and three-body potential, we have calculated the spectrum of the four-, five-, and six-particle systems. In all the regions explored, we have found that these systems present two states, one deep and one shallow close to the A-1 threshold. Some universal relations between the energy levels are extracted; in particular, we have estimated the universal ratios between thresholds of the three-, four-, and five-particle continua using the two-body Gaussian potential. They agree with recent measurements and theoretical predictions.

θ and the η ' in large N supersymmetric QCD

DOE PAGES

Dine, Michael; Draper, Patrick; Stephenson-Haskins, Laurel; ...

2017-05-22

Here, we study the large N θ dependence and the η' potential in supersymmetric QCD with small soft SUSY-breaking terms. Known exact results in SUSY QCD are found to reflect a variety of expectations from large N perturbation theory, including the presence of branches and the behavior of theories with matter (both with N f << N and N f ~ N ). But, there are also striking departures from ordinary QCD and the conventional large N description: instanton effects, when under control, are not exponentially suppressed at large N , and branched structure in supersymmetric QCD is always associatedmore » with approximate discrete symmetries. We suggest that these differences motivate further study of large N QCD on the lattice.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dine, Michael; Draper, Patrick; Stephenson-Haskins, Laurel

Here, we study the large N θ dependence and the η' potential in supersymmetric QCD with small soft SUSY-breaking terms. Known exact results in SUSY QCD are found to reflect a variety of expectations from large N perturbation theory, including the presence of branches and the behavior of theories with matter (both with N f << N and N f ~ N ). But, there are also striking departures from ordinary QCD and the conventional large N description: instanton effects, when under control, are not exponentially suppressed at large N , and branched structure in supersymmetric QCD is always associatedmore » with approximate discrete symmetries. We suggest that these differences motivate further study of large N QCD on the lattice.« less

Elastic and inelastic scattering for the 10B+58Ni system at near-barrier energies

NASA Astrophysics Data System (ADS)

Scarduelli, V.; Crema, E.; Guimarães, V.; Abriola, D.; Arazi, A.; de Barbará, E.; Capurro, O. A.; Cardona, M. A.; Gallardo, J.; Hojman, D.; Martí, G. V.; Pacheco, A. J.; Rodrígues, D.; Yang, Y. Y.; Deshmukh, N. N.; Paes, B.; Lubian, J.; Mendes Junior, D. R.; Morcelle, V.; Monteiro, D. S.

2017-11-01

Full angular distributions of the 10B elastically and inelastically scattered by 58Ni have been measured at different energies around the Coulomb barrier. The elastic and inelastic scattering of 10B on a medium mass target has been measured for the first time. The obtained angular distributions have been analyzed in terms of large-scale coupled reaction channel calculations, where several inelastic transitions of the projectile and the target, as well as the most relevant one- and two-step transfer reactions have been included in the coupling matrix. The roles of the spin reorientation, the spin-orbit interaction, and the large ground-state deformation of the 10B, in the reaction mechanism, were also investigated. The real part of the interaction potential between projectile and target was represented by a parameter-free double-folding potential, whereas no imaginary potential at the surface was considered. In this sense, the theoretical calculations were parameter free and their results were compared to experimental data to investigate the relative importance of the different reaction channels. A striking influence of the ground-state spin reorientation of the 10B nucleus was found, while all transfer reactions investigated had a minimum contribution to the dynamics of the system. Finally, the large static deformation of the 10B and the spin-orbit coupling can also play an important role in the system studied.

Biogas Production from Sugarcane Waste: Assessment on Kinetic Challenges for Process Designing.

PubMed

Janke, Leandro; Leite, Athaydes; Nikolausz, Marcell; Schmidt, Thomas; Liebetrau, Jan; Nelles, Michael; Stinner, Walter

2015-08-31

Biogas production from sugarcane waste has large potential for energy generation, however, to enable the optimization of the anaerobic digestion (AD) process each substrate characteristic should be carefully evaluated. In this study, the kinetic challenges for biogas production from different types of sugarcane waste were assessed. Samples of vinasse, filter cake, bagasse, and straw were analyzed in terms of total and volatile solids, chemical oxygen demand, macronutrients, trace elements, and nutritional value. Biochemical methane potential assays were performed to evaluate the energy potential of the substrates according to different types of sugarcane plants. Methane yields varied considerably (5-181 Nm³·tonFM(-1)), mainly due to the different substrate characteristics and sugar and/or ethanol production processes. Therefore, for the optimization of AD on a large-scale, continuous stirred-tank reactor with long hydraulic retention times (>35 days) should be used for biogas production from bagasse and straw, coupled with pre-treatment process to enhance the degradation of the fibrous carbohydrates. Biomass immobilization systems are recommended in case vinasse is used as substrate, due to its low solid content, while filter cake could complement the biogas production from vinasse during the sugarcane offseason, providing a higher utilization of the biogas system during the entire year.

Biogas Production from Sugarcane Waste: Assessment on Kinetic Challenges for Process Designing

PubMed Central

Janke, Leandro; Leite, Athaydes; Nikolausz, Marcell; Schmidt, Thomas; Liebetrau, Jan; Nelles, Michael; Stinner, Walter

2015-01-01

Biogas production from sugarcane waste has large potential for energy generation, however, to enable the optimization of the anaerobic digestion (AD) process each substrate characteristic should be carefully evaluated. In this study, the kinetic challenges for biogas production from different types of sugarcane waste were assessed. Samples of vinasse, filter cake, bagasse, and straw were analyzed in terms of total and volatile solids, chemical oxygen demand, macronutrients, trace elements, and nutritional value. Biochemical methane potential assays were performed to evaluate the energy potential of the substrates according to different types of sugarcane plants. Methane yields varied considerably (5–181 Nm3·tonFM−1), mainly due to the different substrate characteristics and sugar and/or ethanol production processes. Therefore, for the optimization of AD on a large-scale, continuous stirred-tank reactor with long hydraulic retention times (>35 days) should be used for biogas production from bagasse and straw, coupled with pre-treatment process to enhance the degradation of the fibrous carbohydrates. Biomass immobilization systems are recommended in case vinasse is used as substrate, due to its low solid content, while filter cake could complement the biogas production from vinasse during the sugarcane offseason, providing a higher utilization of the biogas system during the entire year. PMID:26404248

Li Isotope Studies of Olivine in Mantle Xenoliths by SIMS

NASA Technical Reports Server (NTRS)

Bell, D. R.; Hervig, R. L.; Buseck, P. R.

2005-01-01

Variations in the ratio of the stable isotopes of Li are a potentially powerful tracer of processes in planetary and nebular environments [1]. Large differences in the 7Li/6Li ratio between the terrestrial upper mantle and various crustal materials make Li isotope composition a potentially powerful tracer of crustal recycling processes on Earth [2]. Recent SIMS studies of terrestrial mantle and Martian meteorite samples report intra-mineral Li isotope zoning [3-5]. Substantial Li isotope heterogeneity also exists within and between the components of chondritic meteorites [6,7]. Experimental studies of Li diffusion suggest the potential for rapid isotope exchange at elevated temperatures [8]. Large variations in 7Li, exceeding the range of unaltered basalts, occur in terrestrial mantle-derived xenoliths from individual localities [9]. The origins of these variations are not fully understood.

The use of DRG for identifying clinical trials centers with high recruitment potential: a feasability study.

PubMed

Aegerter, Philippe; Bendersky, Noelle; Tran, Thi-Chien; Ropers, Jacques; Taright, Namik; Chatellier, Gilles

2014-01-01

Recruitment of large samples of patients is crucial for evidence level and efficacy of clinical trials (CT). Clinical Trial Recruitment Support Systems (CTRSS) used to estimate patient recruitment are generally specific to Hospital Information Systems and few were evaluated on a large number of trials. Our aim was to assess, on a large number of CT, the usefulness of commonly available data as Diagnosis Related Groups (DRG) databases in order to estimate potential recruitment. We used the DRG database of a large French multicenter medical institution (1.2 million inpatient stays and 400 new trials each year). Eligibility criteria of protocols were broken down into in atomic entities (diagnosis, procedures, treatments...) then translated into codes and operators recorded in a standardized form. A program parsed the forms and generated requests on the DRG database. A large majority of selection criteria could be coded and final estimations of number of eligible patients were close to observed ones (median difference = 25). Such a system could be part of the feasability evaluation and center selection process before the start of the clinical trial.

Pathobiology of Anaplastic Large Cell Lymphoma

PubMed Central

Piccaluga, Pier Paolo; Gazzola, Anna; Mannu, Claudia; Agostinelli, Claudio; Bacci, Francesco; Sabattini, Elena; Sagramoso, Carlo; Piva, Roberto; Roncolato, Fernando; Inghirami, Giorgio; Pileri, Stefano A.

2010-01-01

The authors revise the concept of anaplastic large cell lymphoma (ALCL) in the light of the recently updated WHO classification of Tumors of Hematopoietic and Lymphoid Tissues both on biological and clinical grounds. The main histological findings are illustrated with special reference to the cytological spectrum that is indeed characteristic of the tumor. The phenotype is reported in detail: the expression of the ALK protein as well as the chromosomal abnormalities is discussed with their potential pathogenetic implications. The clinical features of ALCL are presented by underlining the difference in terms of response to therapy and survival between the ALK-positive and ALK-negative forms. Finally, the biological rationale for potential innovative targeted therapies is presented. PMID:21331150

Stable isotopes in collagen and Late Quaternary carnivore palaeoecology

NASA Astrophysics Data System (ADS)

Bocherens, Hervé

2010-05-01

Several taxa of large carnivores co-occurred during the late Pleistocene in the steppe-tundra ecosystem, such as wolf Canis lupus, cave lion Panthera leo spelaea, cave hyaena Crocuta crocuta spelaea, brown bear Ursus arctos and cave bear Ursus spelaeus and Ursus ingressus. This abundance of taxa belonging to the same guild raises questions about niche partitioning, especially in terms of dietary specialization and prey selection. Observations of the dietary ecology of the extant relatives of these late Pleistocene carnivores does not provide unambiguous answers as these populations live under very different environmental conditions where other potential prey species are present, but it appears that most of these modern large carnivores are relatively flexible in their prey selection. Palaeontological investigations dealing with faunal associations and activity marks on fossil bones also have their limitations, such as taphonomic biases (palimpsests rather than biological associations) and do not allow the quantification of consumption of various preys. In contrast, carbon and nitrogen isotopic signatures of bone collagen depend directly on those of the average diet. Since different potential prey species occurring in the steppe-tundra exhibit consistent isotopic differences for these chemical elements, it is possible to relate the carbon and nitrogen isotopic signatures measured in fossil carnivores with the preferential consumption of some prey species. Some amount of quantification can be provided using modified versions of mixing models developed for modern ecosystems. In addition, this isotopic approach is individual-based and it is therefore possible to investigate intra- and inter-population differences in prey selection, as well as possible chronological trends and differences linked to genetic differences by combining isotopic and ancient DNA studies on the same material. The isotopic approach has already shown that among the tested large carnivores, cave bears of various genetic types are overwhelmingly vegetarian while coeval brown bears are essentially carnivores, cave lions have a marked preference for reindeer, and none of the large carnivores match Neanderthals in terms of megaherbivore consumption (i.e. woolly mammoth and woolly rhinoceros).

3. Neural changes in different gravity and ecophysiological environments - A survey

NASA Astrophysics Data System (ADS)

Slenzka, K.

Neural changes or neuronal plasticity occur after and during different stimulations and inputs in general. Gravity is one major input to the brain transferred from the vestibular system. However, often also direct effects of gravity on the cellular level are discussed. Our group was investigating the influence of different gravity environments on a large variety of neuronal enzymes in the developing fish brain. Long-term space travel or bases on Moon and Mars will have to deal not only with neural changes based on the different gravity environment, but also with potential negative or even toxic changes in the respective life support system. Our goal is now to identify reported enzyme activity changes in the brain based for example on potential toxic drugs or endocrine disruptors in combination with gravity induced changes. In this paper a survey will be undertaken discussing recent results obtained in ecotoxicology, gravitational biology combined with new data from our group regarding potential differences in brain glucose-6-phosphate dehydrogenase of medaka and zebrafish.

Direct computation of general chemical energy differences: Application to ionization potentials, excitation, and bond energies.

PubMed

Beste, A; Harrison, R J; Yanai, T

2006-08-21

Chemists are mainly interested in energy differences. In contrast, most quantum chemical methods yield the total energy which is a large number compared to the difference and has therefore to be computed to a higher relative precision than would be necessary for the difference alone. Hence, it is desirable to compute energy differences directly, thereby avoiding the precision problem. Whenever it is possible to find a parameter which transforms smoothly from an initial to a final state, the energy difference can be obtained by integrating the energy derivative with respect to that parameter (cf. thermodynamic integration or adiabatic connection methods). If the dependence on the parameter is predominantly linear, accurate results can be obtained by single-point integration. In density functional theory and Hartree-Fock, we applied the formalism to ionization potentials, excitation energies, and chemical bond breaking. Example calculations for ionization potentials and excitation energies showed that accurate results could be obtained with a linear estimate. For breaking bonds, we introduce a nongeometrical parameter which gradually turns the interaction between two fragments of a molecule on. The interaction changes the potentials used to determine the orbitals as well as the constraint on the orbitals to be orthogonal.

Theoretical characterization of the potential energy surface for NH + NO

NASA Technical Reports Server (NTRS)

Walch, Stephen P.

1993-01-01

The potential energy surface for NH + NO was characterized using complete active space self-consistent field (CASSCF) gradient calculation to determine the stationary point geometries and frequencies followed by CASSCF/internally contracted configuration interaction calculations to refine the energetics. The present results are in qualitative accord with the BAC-MP4 calculations, but there are differences as large as 8 kcal/mol in the detailed energetics.

Unexpectedly large impact of forest management and grazing on global vegetation biomass

NASA Astrophysics Data System (ADS)

Erb, Karl-Heinz; Kastner, Thomas; Plutzar, Christoph; Bais, Anna Liza S.; Carvalhais, Nuno; Fetzel, Tamara; Gingrich, Simone; Haberl, Helmut; Lauk, Christian; Niedertscheider, Maria; Pongratz, Julia; Thurner, Martin; Luyssaert, Sebastiaan

2018-01-01

Carbon stocks in vegetation have a key role in the climate system. However, the magnitude, patterns and uncertainties of carbon stocks and the effect of land use on the stocks remain poorly quantified. Here we show, using state-of-the-art datasets, that vegetation currently stores around 450 petagrams of carbon. In the hypothetical absence of land use, potential vegetation would store around 916 petagrams of carbon, under current climate conditions. This difference highlights the massive effect of land use on biomass stocks. Deforestation and other land-cover changes are responsible for 53-58% of the difference between current and potential biomass stocks. Land management effects (the biomass stock changes induced by land use within the same land cover) contribute 42-47%, but have been underestimated in the literature. Therefore, avoiding deforestation is necessary but not sufficient for mitigation of climate change. Our results imply that trade-offs exist between conserving carbon stocks on managed land and raising the contribution of biomass to raw material and energy supply for the mitigation of climate change. Efforts to raise biomass stocks are currently verifiable only in temperate forests, where their potential is limited. By contrast, large uncertainties hinder verification in the tropical forest, where the largest potential is located, pointing to challenges for the upcoming stocktaking exercises under the Paris agreement.

Unexpectedly large impact of forest management and grazing on global vegetation biomass.

PubMed

Erb, Karl-Heinz; Kastner, Thomas; Plutzar, Christoph; Bais, Anna Liza S; Carvalhais, Nuno; Fetzel, Tamara; Gingrich, Simone; Haberl, Helmut; Lauk, Christian; Niedertscheider, Maria; Pongratz, Julia; Thurner, Martin; Luyssaert, Sebastiaan

2018-01-04

Carbon stocks in vegetation have a key role in the climate system. However, the magnitude, patterns and uncertainties of carbon stocks and the effect of land use on the stocks remain poorly quantified. Here we show, using state-of-the-art datasets, that vegetation currently stores around 450 petagrams of carbon. In the hypothetical absence of land use, potential vegetation would store around 916 petagrams of carbon, under current climate conditions. This difference highlights the massive effect of land use on biomass stocks. Deforestation and other land-cover changes are responsible for 53-58% of the difference between current and potential biomass stocks. Land management effects (the biomass stock changes induced by land use within the same land cover) contribute 42-47%, but have been underestimated in the literature. Therefore, avoiding deforestation is necessary but not sufficient for mitigation of climate change. Our results imply that trade-offs exist between conserving carbon stocks on managed land and raising the contribution of biomass to raw material and energy supply for the mitigation of climate change. Efforts to raise biomass stocks are currently verifiable only in temperate forests, where their potential is limited. By contrast, large uncertainties hinder verification in the tropical forest, where the largest potential is located, pointing to challenges for the upcoming stocktaking exercises under the Paris agreement.

Unexpectedly large impact of forest management and grazing on global vegetation biomass

PubMed Central

Erb, K.-H.; Bais, A.L.S.; Carvalhais, N.; Fetzel, T.; Gingrich, S.; Haberl, H.; Lauk, C.; Niedertscheider, M.; Pongratz, J.; Thurner, M.; Luyssaert, S.

2017-01-01

Carbon stocks in vegetation play a key role in the climate system1–4, but their magnitude and patterns, their uncertainties, and the impact of land use on them remain poorly quantified. Based on a consistent integration of state-of-the art datasets, we show that vegetation currently stores ~450 PgC. In the hypothetical absence of land use, potential vegetation would store ~916 PgC, under current climate. This difference singles out the massive effect land use has on biomass stocks. Deforestation and other land-cover changes are responsible for 53-58% of the difference between current and potential biomass stocks. Land management effects, i.e. land-use induced biomass stock changes within the same land cover, contribute 42-47% but are underappreciated in the current literature. Avoiding deforestation hence is necessary but not sufficient for climate-change mitigation. Our results imply that trade-offs exist between conserving carbon stocks on managed land and raising the contribution of biomass to raw material and energy supply for climate change mitigation. Efforts to raise biomass stocks are currently only verifiable in temperate forests, where potentials are limited. In contrast, large uncertainties hamper verification in the tropical forest where the largest potentials are located, pointing to challenges for the upcoming stocktaking exercises under the Paris agreement. PMID:29258288

A multi-hypothesis tracker for clicking whales.

PubMed

Baggenstoss, Paul M

2015-05-01

This paper describes a tracker specially designed to track clicking beaked whales using widely spaced bottom-mounted hydrophones, although it can be adapted to different species and sensors. The input to the tracker is a sequence of static localization solutions obtained using time difference of arrival information at widely spaced hydrophones. To effectively handle input localizations with high ambiguity, the tracker is based on multi-hypothesis tracker concepts, so it considers all potential association hypotheses and keeps a large number of potential tracks in memory. The method is demonstrated on actual data and shown to successfully track multiple beaked whales at depth.

Facilitating large-scale clinical trials: in Asia.

PubMed

Choi, Han Yong; Ko, Jae-Wook

2010-01-01

The number of clinical trials conducted in Asian countries has started to increase as a result of expansion of the pharmaceutical market in this area. There is a growing opportunity for large-scale clinical trials because of the large number of patients, significant market potential, good quality of data, and the cost effective and qualified medical infrastructure. However, for carrying out large-scale clinical trials in Asia, there are several major challenges, including the quality control of data, budget control, laboratory validation, monitoring capacity, authorship, staff training, and nonstandard treatment that need to be considered. There are also several difficulties in collaborating on international trials in Asia because Asia is an extremely diverse continent. The major challenges are language differences, diversity of patterns of disease, and current treatments, a large gap in the experience with performing multinational trials, and regulatory differences among the Asian countries. In addition, there are also differences in the understanding of global clinical trials, medical facilities, indemnity assurance, and culture, including food and religion. To make regional and local data provide evidence for efficacy through the standardization of these differences, unlimited effort is required. At this time, there are no large clinical trials led by urologists in Asia, but it is anticipated that the role of urologists in clinical trials will continue to increase. Copyright © 2010 Elsevier Inc. All rights reserved.

Predicting climate-induced range shifts: model differences and model reliability.

Treesearch

Joshua J. Lawler; Denis White; Ronald P. Neilson; Andrew R. Blaustein

2006-01-01

Predicted changes in the global climate are likely to cause large shifts in the geographic ranges of many plant and animal species. To date, predictions of future range shifts have relied on a variety of modeling approaches with different levels of model accuracy. Using a common data set, we investigated the potential implications of alternative modeling approaches for...

A robust clustering algorithm for identifying problematic samples in genome-wide association studies.

PubMed

Bellenguez, Céline; Strange, Amy; Freeman, Colin; Donnelly, Peter; Spencer, Chris C A

2012-01-01

High-throughput genotyping arrays provide an efficient way to survey single nucleotide polymorphisms (SNPs) across the genome in large numbers of individuals. Downstream analysis of the data, for example in genome-wide association studies (GWAS), often involves statistical models of genotype frequencies across individuals. The complexities of the sample collection process and the potential for errors in the experimental assay can lead to biases and artefacts in an individual's inferred genotypes. Rather than attempting to model these complications, it has become a standard practice to remove individuals whose genome-wide data differ from the sample at large. Here we describe a simple, but robust, statistical algorithm to identify samples with atypical summaries of genome-wide variation. Its use as a semi-automated quality control tool is demonstrated using several summary statistics, selected to identify different potential problems, and it is applied to two different genotyping platforms and sample collections. The algorithm is written in R and is freely available at www.well.ox.ac.uk/chris-spencer chris.spencer@well.ox.ac.uk Supplementary data are available at Bioinformatics online.

Functional transient receptor potential vanilloid 1 and transient receptor potential vanilloid 4 channels along different segments of the renal vasculature.

PubMed

Chen, L; Kaßmann, M; Sendeski, M; Tsvetkov, D; Marko, L; Michalick, L; Riehle, M; Liedtke, W B; Kuebler, W M; Harteneck, C; Tepel, M; Patzak, A; Gollasch, M

2015-02-01

Transient receptor potential vanilloid 1 (TRPV1) and vanilloid 4 (TRPV4) cation channels have been recently identified to promote endothelium-dependent relaxation of mouse mesenteric arteries. However, the role of TRPV1 and TRPV4 in the renal vasculature is largely unknown. We hypothesized that TRPV1/4 plays a role in endothelium-dependent vasodilation of renal blood vessels. We studied the distribution of functional TRPV1/4 along different segments of the renal vasculature. Mesenteric arteries were studied as control vessels. The TRPV1 agonist capsaicin relaxed mouse mesenteric arteries with an EC50 of 25 nm, but large mouse renal arteries or rat descending vasa recta only at >100-fold higher concentrations. The vasodilatory effect of capsaicin in the low-nanomolar concentration range was endothelium-dependent and absent in vessels of Trpv1 -/- mice. The TRPV4 agonist GSK1016790A relaxed large conducting renal arteries, mesenteric arteries and vasa recta with EC50 of 18, 63 nm and ~10 nm respectively. These effects were endothelium-dependent and inhibited by a TRPV4 antagonist, AB159908 (10 μm). Capsaicin and GSK1016790A produced vascular dilation in isolated mouse perfused kidneys with EC50 of 23 and 3 nm respectively. The capsaicin effects were largely reduced in Trpv1 -/- kidneys, and the effects of GSK1016790A were inhibited in Trpv4 -/- kidneys. Our results demonstrate that two TRPV channels have unique sites of vasoregulatory function in the kidney with functional TRPV1 having a narrow, discrete distribution in the resistance vasculature and TRPV4 having more universal, widespread distribution along different vascular segments. We suggest that TRPV1/4 channels are potent therapeutic targets for site-specific vasodilation in the kidney. © 2014 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Stimulus novelty, task relevance and the visual evoked potential in man

NASA Technical Reports Server (NTRS)

Courchesne, E.; Hillyard, S. A.; Galambos, R.

1975-01-01

The effect of task relevance on P3 (waveform of human evoked potential) waves and the methodologies used to deal with them are outlined. Visual evoked potentials (VEPs) were recorded from normal adult subjects performing in a visual discrimination task. Subjects counted the number of presentations of the numeral 4 which was interposed rarely and randomly within a sequence of tachistoscopically flashed background stimuli. Intrusive, task-irrelevant (not counted) stimuli were also interspersed rarely and randomly in the sequence of 2s; these stimuli were of two types: simples, which were easily recognizable, and novels, which were completely unrecognizable. It was found that the simples and the counted 4s evoked posteriorly distributed P3 waves while the irrelevant novels evoked large, frontally distributed P3 waves. These large, frontal P3 waves to novels were also found to be preceded by large N2 waves. These findings indicate that the P3 wave is not a unitary phenomenon but should be considered in terms of a family of waves, differing in their brain generators and in their psychological correlates.

Influence of combined fundamental potentials in a nonlinear vibration energy harvester

NASA Astrophysics Data System (ADS)

Podder, Pranay; Mallick, Dhiman; Amann, Andreas; Roy, Saibal

2016-11-01

Ambient mechanical vibrations have emerged as a viable energy source for low-power wireless sensor nodes aiming the upcoming era of the ‘Internet of Things’. Recently, purposefully induced dynamical nonlinearities have been exploited to widen the frequency spectrum of vibration energy harvesters. Here we investigate some critical inconsistencies between the theoretical formulation and applications of the bistable Duffing nonlinearity in vibration energy harvesting. A novel nonlinear vibration energy harvesting device with the capability to switch amidst individually tunable bistable-quadratic, monostable-quartic and bistable-quartic potentials has been designed and characterized. Our study highlights the fundamentally different large deflection behaviors of the theoretical bistable-quartic Duffing oscillator and the experimentally adapted bistable-quadratic systems, and underlines their implications in the respective spectral responses. The results suggest enhanced performance in the bistable-quartic potential in comparison to others, primarily due to lower potential barrier and higher restoring forces facilitating large amplitude inter-well motion at relatively lower accelerations.

Avoiding 100 new power plants by increasing efficiency of room air conditioners in India: opportunities and challenges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phadke, Amol; Abhyankar, Nikit; Shah, Nihar

Electricity demand for room ACs is growing very rapidly in emerging economies such as India. We estimate the electricity demand from room ACs in 2030 in India considering factors such as weather and income growth using market data on penetration of ACs in different income classes and climatic regions. We discuss the status of the current standards, labels, and incentive programs to improve the efficiency of room ACs in these markets and assess the potential for further large improvements in efficiency and find that efficiency can be improved by over 40% cost effectively. The total potential energy savings from Roommore » AC efficiency improvement in India using the best available technology will reach over 118 TWh in 2030; potential peak demand saving is found to be 60 GW by 2030. This is equivalent to avoiding 120 new coal fired power plants of 500 MW each. We discuss policy options to complement, expand and improve the ongoing programs to capture this large potential.« less

The Effect of Reduction Potential on the Generation of the Perylene Diimide Radical Anions

NASA Astrophysics Data System (ADS)

Zhao, Y. Z.; Li, K. X.; Ding, S. Y.; Zhu, M.; Ren, H. P.; Ma, Q.; Guo, Z.; Tian, S. P.; Zhang, H. Q.; Miao, Z. C.

2018-07-01

Perylene diimide derivatives (PDIs) with different substituents in the bay positions (Un-PDI, DFPDI and THBPDI) were chosen in this report to investigate the effect of potential on the reduction of PDIs through base (hydrazine, 1,2-ethanediamine and triethylamine)-driven keto-enol anion tautomerism. The reduction potentials (PDI/PDI•-) of these compounds determined via cyclic voltammetry are -0.51, ‒0.34, and -0.098 V for Un-PDI, DFPDI, and THBPDI, respectively. The reduction of Un-PDI, DFPDI and THBPDI by hydrazine can produce corresponding radical anions and dianions, but the volume of hydrazine added at which the radicals started to appear is different and depends on their reduction potential. The similar phenomenon was observed using 1,2-ethylenediamine and triethylamine. However, only the radical anion was obtained even in a large excess of 1,2-ethanediamine or triethylamine. Moreover, the reduction of these PDIs with different bases added in the same amount was investigated, and the correlation with their basicity was shown.

Insight into Environmental Effects on Bonding and Redox Properties of [4Fe-4S] Clusters in Proteins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Shuqiang; Ichiye, Toshiko

The large differences in redox potentials between the HiPIPs and ferredoxins are generally attributed to hydrogen bonds and electrostatic effects from the protein and solvent. Recent ligand K-edge X-ray absorption studies by Solomon and co-workers show that the Fe-S covalencies of [4Fe-4S] clusters in the two proteins differ considerably apparently because of hydrogen bonds from water, indicating electronic effects may be important. However, combined density function theory (DFT) and photoelectron spectroscopy studies by our group and Wang and co-workers indicate that hydrogen bonds tune the potential of [4Fe-4S] clusters by mainly electrostatics. The DFT studies here rationalize both results, namelymore » that the observed change in the Fe-S covalency is due to differences in ligand conformation between the two proteins rather than hydrogen bonds. Moreover, the ligand conformation affects the calculated potentials by 100 mV and, thus, is a heretofore unconsidered means of tuning the potential.« less

Modeling Molecular Interactions in Water: From Pairwise to Many-Body Potential Energy Functions

PubMed Central

2016-01-01

Almost 50 years have passed from the first computer simulations of water, and a large number of molecular models have been proposed since then to elucidate the unique behavior of water across different phases. In this article, we review the recent progress in the development of analytical potential energy functions that aim at correctly representing many-body effects. Starting from the many-body expansion of the interaction energy, specific focus is on different classes of potential energy functions built upon a hierarchy of approximations and on their ability to accurately reproduce reference data obtained from state-of-the-art electronic structure calculations and experimental measurements. We show that most recent potential energy functions, which include explicit short-range representations of two-body and three-body effects along with a physically correct description of many-body effects at all distances, predict the properties of water from the gas to the condensed phase with unprecedented accuracy, thus opening the door to the long-sought “universal model” capable of describing the behavior of water under different conditions and in different environments. PMID:27186804

Interhemispheric differences in ionospheric convection: Cluster EDI observations revisited

NASA Astrophysics Data System (ADS)

Förster, M.; Haaland, S.

2015-07-01

The interaction between the interplanetary magnetic field and the geomagnetic field sets up a large-scale circulation in the magnetosphere. This circulation is also reflected in the magnetically connected ionosphere. In this paper, we present a study of ionospheric convection based on Cluster Electron Drift Instrument (EDI) satellite measurements covering both hemispheres and obtained over a full solar cycle. The results from this study show that average flow patterns and polar cap potentials for a given orientation of the interplanetary magnetic field can be very different in the two hemispheres. In particular during southward directed interplanetary magnetic field conditions, and thus enhanced energy input from the solar wind, the measurements show that the southern polar cap has a higher cross polar cap potential. There are persistent north-south asymmetries, which cannot easily be explained by the influence of external drivers. These persistent asymmetries are primarily a result of the significant differences in the strength and configuration of the geomagnetic field between the Northern and Southern Hemispheres. Since the ionosphere is magnetically connected to the magnetosphere, this difference will also be reflected in the magnetosphere in the form of different feedback from the two hemispheres. Consequently, local ionospheric conditions and the geomagnetic field configuration are important for north-south asymmetries in large regions of geospace.

Young's moduli of carbon materials investigated by various classical molecular dynamics schemes

NASA Astrophysics Data System (ADS)

Gayk, Florian; Ehrens, Julian; Heitmann, Tjark; Vorndamme, Patrick; Mrugalla, Andreas; Schnack, Jürgen

2018-05-01

For many applications classical carbon potentials together with classical molecular dynamics are employed to calculate structures and physical properties of such carbon-based materials where quantum mechanical methods fail either due to the excessive size, irregular structure or long-time dynamics. Although such potentials, as for instance implemented in LAMMPS, yield reasonably accurate bond lengths and angles for several carbon materials such as graphene, it is not clear how accurate they are in terms of mechanical properties such as for instance Young's moduli. We performed large-scale classical molecular dynamics investigations of three carbon-based materials using the various potentials implemented in LAMMPS as well as the EDIP potential of Marks. We show how the Young's moduli vary with classical potentials and compare to experimental results. Since classical descriptions of carbon are bound to be approximations it is not astonishing that different realizations yield differing results. One should therefore carefully check for which observables a certain potential is suited. Our aim is to contribute to such a clarification.

A theoretical study of the adiabatic and vertical ionization potentials of water.

PubMed

Feller, David; Davidson, Ernest R

2018-06-21

Theoretical predictions of the three lowest adiabatic and vertical ionization potentials of water were obtained from the Feller-Peterson-Dixon approach. This approach combines multiple levels of coupled cluster theory with basis sets as large as aug-cc-pV8Z in some cases and various corrections up to and including full configuration interaction theory. While agreement with experiment for the adiabatic ionization potential of the lowest energy 2 B 1 state was excellent, differences for other states were much larger, sometimes exceeding 10 kcal/mol (0.43 eV). Errors of this magnitude are inconsistent with previous benchmark work on 52 adiabatic ionization potentials, where a root mean square of 0.20 kcal/mol (0.009 eV) was found. Difficulties in direct comparisons between theory and experiment for vertical ionization potentials are discussed. With regard to the differences found for the 2 A 1 / 2 Π u and 2 B 2 adiabatic ionization potentials, a reinterpretation of the experimental spectrum appears justified.

Existence domains of arbitrary amplitude nonlinear structures in two-electron temperature space plasmas. II. High-frequency electron-acoustic solitons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maharaj, S. K.; Bharuthram, R.; Singh, S. V.

2012-12-15

A three-component plasma model composed of ions, cool electrons, and hot electrons is adopted to investigate the existence of large amplitude electron-acoustic solitons not only for the model for which inertia and pressure are retained for all plasma species which are assumed to be adiabatic but also neglecting inertial effects of the hot electrons. Using the Sagdeev potential formalism, the Mach number ranges supporting the existence of large amplitude electron-acoustic solitons are presented. The limitations on the attainable amplitudes of electron-acoustic solitons having negative potentials are attributed to a number of different physical reasons, such as the number density ofmore » either the cool electrons or hot electrons ceases to be real valued beyond the upper Mach number limit, or, alternatively, a negative potential double layer occurs. Electron-acoustic solitons having positive potentials are found to be supported only if inertial effects of the hot electrons are retained and these are found to be limited only by positive potential double layers.« less

Electrostatic field of the large fragment of Escherichia coli DNA polymerase I.

PubMed

Warwicker, J; Ollis, D; Richards, F M; Steitz, T A

1985-12-05

The electrostatic field of the large fragment of Escherichia coli DNA polymerase I (Klenow fragment) has been calculated by the finite difference procedure on a 2 A grid. The potential field is substantially negative at physiological pH (reflecting the net negative charge at this pH). The largest regions of positive potential are in the deep crevice of the C-terminal domain, which is the proposed binding site for the DNA substrate. Within the crevice, the electrostatic potential has a partly helical form. If the DNA is positioned to fulfil stereochemical requirements, then the positive potential generally follows the major groove and (to a lesser extent) the negative potential is in the minor groove. Such an arrangement could stabilize DNA configurations related by screw symmetry. The histidine residues of the Klenow fragment give the positive field of the groove a sensitivity to relatively small pH changes around neutrality. We suggest that the histidine residues could change their ionization states in response to DNA binding, and that this effect could contribute to the protein-DNA binding energy.

Standardized Method for High-throughput Sterilization of Arabidopsis Seeds.

PubMed

Lindsey, Benson E; Rivero, Luz; Calhoun, Chistopher S; Grotewold, Erich; Brkljacic, Jelena

2017-10-17

Arabidopsis thaliana (Arabidopsis) seedlings often need to be grown on sterile media. This requires prior seed sterilization to prevent the growth of microbial contaminants present on the seed surface. Currently, Arabidopsis seeds are sterilized using two distinct sterilization techniques in conditions that differ slightly between labs and have not been standardized, often resulting in only partially effective sterilization or in excessive seed mortality. Most of these methods are also not easily scalable to a large number of seed lines of diverse genotypes. As technologies for high-throughput analysis of Arabidopsis continue to proliferate, standardized techniques for sterilizing large numbers of seeds of different genotypes are becoming essential for conducting these types of experiments. The response of a number of Arabidopsis lines to two different sterilization techniques was evaluated based on seed germination rate and the level of seed contamination with microbes and other pathogens. The treatments included different concentrations of sterilizing agents and times of exposure, combined to determine optimal conditions for Arabidopsis seed sterilization. Optimized protocols have been developed for two different sterilization methods: bleach (liquid-phase) and chlorine (Cl2) gas (vapor-phase), both resulting in high seed germination rates and minimal microbial contamination. The utility of these protocols was illustrated through the testing of both wild type and mutant seeds with a range of germination potentials. Our results show that seeds can be effectively sterilized using either method without excessive seed mortality, although detrimental effects of sterilization were observed for seeds with lower than optimal germination potential. In addition, an equation was developed to enable researchers to apply the standardized chlorine gas sterilization conditions to airtight containers of different sizes. The protocols described here allow easy, efficient, and inexpensive seed sterilization for a large number of Arabidopsis lines.

Standardized Method for High-throughput Sterilization of Arabidopsis Seeds

PubMed Central

Calhoun, Chistopher S.; Grotewold, Erich; Brkljacic, Jelena

2017-01-01

Arabidopsis thaliana (Arabidopsis) seedlings often need to be grown on sterile media. This requires prior seed sterilization to prevent the growth of microbial contaminants present on the seed surface. Currently, Arabidopsis seeds are sterilized using two distinct sterilization techniques in conditions that differ slightly between labs and have not been standardized, often resulting in only partially effective sterilization or in excessive seed mortality. Most of these methods are also not easily scalable to a large number of seed lines of diverse genotypes. As technologies for high-throughput analysis of Arabidopsis continue to proliferate, standardized techniques for sterilizing large numbers of seeds of different genotypes are becoming essential for conducting these types of experiments. The response of a number of Arabidopsis lines to two different sterilization techniques was evaluated based on seed germination rate and the level of seed contamination with microbes and other pathogens. The treatments included different concentrations of sterilizing agents and times of exposure, combined to determine optimal conditions for Arabidopsis seed sterilization. Optimized protocols have been developed for two different sterilization methods: bleach (liquid-phase) and chlorine (Cl2) gas (vapor-phase), both resulting in high seed germination rates and minimal microbial contamination. The utility of these protocols was illustrated through the testing of both wild type and mutant seeds with a range of germination potentials. Our results show that seeds can be effectively sterilized using either method without excessive seed mortality, although detrimental effects of sterilization were observed for seeds with lower than optimal germination potential. In addition, an equation was developed to enable researchers to apply the standardized chlorine gas sterilization conditions to airtight containers of different sizes. The protocols described here allow easy, efficient, and inexpensive seed sterilization for a large number of Arabidopsis lines. PMID:29155739

Construction of the landscape for multi-stable systems: Potential landscape, quasi-potential, A-type integral and beyond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Peijie, E-mail: cliffzhou@pku.edu.cn; Li, Tiejun, E-mail: tieli@pku.edu.cn

Motivated by the famous Waddington’s epigenetic landscape metaphor in developmental biology, biophysicists and applied mathematicians made different proposals to construct the landscape for multi-stable complex systems. We aim to summarize and elucidate the relationships among these theories from a mathematical point of view. We systematically investigate and compare three different but closely related realizations in the recent literature: the Wang’s potential landscape theory from steady state distribution of stochastic differential equations (SDEs), the Freidlin-Wentzell quasi-potential from the large deviation theory, and the construction through SDE decomposition and A-type integral. We revisit that the quasi-potential is the zero noise limit ofmore » the potential landscape, and the potential function in the third proposal coincides with the quasi-potential. We compare the difference between local and global quasi-potential through the viewpoint of exchange of limit order for time and noise amplitude. We argue that local quasi-potentials are responsible for getting transition rates between neighboring stable states, while the global quasi-potential mainly characterizes the residence time of the states as the system reaches stationarity. The difference between these two is prominent when the transitivity property is broken. The most probable transition path by minimizing the Onsager-Machlup or Freidlin-Wentzell action functional is also discussed. As a consequence of the established connections among different proposals, we arrive at the novel result which guarantees the existence of SDE decomposition while denies its uniqueness in general cases. It is, therefore, clarified that the A-type integral is more appropriate to be applied to the decomposed SDEs rather than its primitive form as believed by previous researchers. Our results contribute to a deeper understanding of landscape theories for biological systems.« less

Construction of the landscape for multi-stable systems: Potential landscape, quasi-potential, A-type integral and beyond

NASA Astrophysics Data System (ADS)

Zhou, Peijie; Li, Tiejun

2016-03-01

Motivated by the famous Waddington's epigenetic landscape metaphor in developmental biology, biophysicists and applied mathematicians made different proposals to construct the landscape for multi-stable complex systems. We aim to summarize and elucidate the relationships among these theories from a mathematical point of view. We systematically investigate and compare three different but closely related realizations in the recent literature: the Wang's potential landscape theory from steady state distribution of stochastic differential equations (SDEs), the Freidlin-Wentzell quasi-potential from the large deviation theory, and the construction through SDE decomposition and A-type integral. We revisit that the quasi-potential is the zero noise limit of the potential landscape, and the potential function in the third proposal coincides with the quasi-potential. We compare the difference between local and global quasi-potential through the viewpoint of exchange of limit order for time and noise amplitude. We argue that local quasi-potentials are responsible for getting transition rates between neighboring stable states, while the global quasi-potential mainly characterizes the residence time of the states as the system reaches stationarity. The difference between these two is prominent when the transitivity property is broken. The most probable transition path by minimizing the Onsager-Machlup or Freidlin-Wentzell action functional is also discussed. As a consequence of the established connections among different proposals, we arrive at the novel result which guarantees the existence of SDE decomposition while denies its uniqueness in general cases. It is, therefore, clarified that the A-type integral is more appropriate to be applied to the decomposed SDEs rather than its primitive form as believed by previous researchers. Our results contribute to a deeper understanding of landscape theories for biological systems.

Characterization of AA2024-T3 by scanning Kelvin probe force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmutz, P.; Frankel, G.S.

1998-07-01

Volta potential mapping of AA2024-T3 on surfaces was performed with an atomic force microscope. A linear relation was found between the Volta potential measured in air and the corrosion potential in aqueous solution for a range of pure metal samples, indicating that this potential is a measurement of the practical nobility of the surface. Large differences in the Volta potential of intermetallic particles in AA2024-T3 and the matrix phase resulted in a potential map with high contrast that clearly identifies the location of the particles. All intermetallic particles, including the Mg-containing S-phase particles, had a Volta potential noble to thatmore » of the matrix. Surface films on the particles and the matrix were found to have strong effects on the potential, and probably explain the noble nature of the Mg-containing particles, which have been reported to be active to the matrix in solution. The effect of these surface films was examined by refreshing the sample surface using different techniques. Lateral heterogeneities in certain intermetallic particles were also revealed.« less

Simulation and analysis of soil-water conditions in the Great Plains and adjacent areas, central United States, 1951-80

USGS Publications Warehouse

Dugan, Jack T.; Zelt, Ronald B.

2000-01-01

Ground-water recharge and consumptive-irrigation requirements in the Great Plains and adjacent areas largely depend upon an environment extrinsic to the ground-water system. This extrinsic environment, which includes climate, soils, and vegetation, determines the water demands of evapotranspiration, the availability of soil water to meet these demands, and the quantity of soil water remaining for potential ground-water recharge after these demands are met. The geographic extent of the Great Plains contributes to large regional differences among all elements composing the extrinsic environment, particularly the climatic factors. A soil-water simulation program, SWASP, which synthesizes selected climatic, soil, and vegetation factors, was used to simulate the regional soil-water conditions during 1951-80. The output from SWASP consists of several soil-water characteristics, including surface runoff, infiltration, consumptive water requirements, actual evapotranspiration, potential recharge or deep percolation under various conditions, consumptive irrigation requirements, and net fluxes from the ground-water system under irrigated conditions. Simulation results indicate that regional patterns of potential recharge, consumptive irrigation requirements, and net fluxes from the ground-water system under irrigated conditions are largely determined by evapotranspiration and precipitation. The local effects of soils and vegetation on potential recharge cause potential recharge to vary by more than 50 percent in some areas having similar climatic conditions.

Searching for modified growth patterns with tomographic surveys

NASA Astrophysics Data System (ADS)

Zhao, Gong-Bo; Pogosian, Levon; Silvestri, Alessandra; Zylberberg, Joel

2009-04-01

In alternative theories of gravity, designed to produce cosmic acceleration at the current epoch, the growth of large scale structure can be modified. We study the potential of upcoming and future tomographic surveys such as Dark Energy Survey (DES) and Large Synoptic Survey Telescope (LSST), with the aid of cosmic microwave background (CMB) and supernovae data, to detect departures from the growth of cosmic structure expected within general relativity. We employ parametric forms to quantify the potential time- and scale-dependent variation of the effective gravitational constant and the differences between the two Newtonian potentials. We then apply the Fisher matrix technique to forecast the errors on the modified growth parameters from galaxy clustering, weak lensing, CMB, and their cross correlations across multiple photometric redshift bins. We find that even with conservative assumptions about the data, DES will produce nontrivial constraints on modified growth and that LSST will do significantly better.

Collapse of axion stars

DOE PAGES

Eby, Joshua; Leembruggen, Madelyn; Suranyi, Peter; ...

2016-12-15

Axion stars, gravitationally bound states of low-energy axion particles, have a maximum mass allowed by gravitational stability. Weakly bound states obtaining this maximum mass have sufficiently large radii such that they are dilute, and as a result, they are well described by a leading-order expansion of the axion potential. Here, heavier states are susceptible to gravitational collapse. Inclusion of higher-order interactions, present in the full potential, can give qualitatively different results in the analysis of collapsing heavy states, as compared to the leading-order expansion. In this work, we find that collapsing axion stars are stabilized by repulsive interactions present inmore » the full potential, providing evidence that such objects do not form black holes. In the last moments of collapse, the binding energy of the axion star grows rapidly, and we provide evidence that a large amount of its energy is lost through rapid emission of relativistic axions.« less

Influence of the narrow {111} planes on axial and planar ion channeling.

PubMed

Motapothula, M; Dang, Z Y; Venkatesan, T; Breese, M B H; Rana, M A; Osman, A

2012-05-11

We report channeling patterns where clearly resolved effects of the narrow {111} planes are observed in axial and planar alignments for 2 MeV protons passing through a 55 nm [001] silicon membrane. At certain axes, such as <213> and <314>, the offset in atomic rows forming the narrow {111} planes results in shielding from the large potential at the wide {111} planes, producing a region of shallow, asymmetric potential from which axial channeling patterns have no plane of symmetry. At small tilts from such axes, different behavior is observed from the wide and narrow {111} planes. At planar alignment, distinctive channeling effects due to the narrow planes are observed. As a consequence of the shallow potential well at the narrow planes, incident protons suffer dechanneled trajectories which are excluded from channeling within the wide planes, resulting in an anomalously large scattered beam at {111} alignment.

A hydrogeomorphic river network model predicts where and why hyporheic exchange is important in large basins

USGS Publications Warehouse

Gomez-Velez, Jesus D.; Harvey, Judson

2014-01-01

Hyporheic exchange has been hypothesized to have basin-scale consequences; however, predictions throughout river networks are limited by available geomorphic and hydrogeologic data and by models that can analyze and aggregate hyporheic exchange flows across large spatial scales. We developed a parsimonious but physically based model of hyporheic flow for application in large river basins: Networks with EXchange and Subsurface Storage (NEXSS). We applied NEXSS across a broad range of geomorphic diversity in river reaches and synthetic river networks. NEXSS demonstrates that vertical exchange beneath submerged bed forms rather than lateral exchange through meanders dominates hyporheic fluxes and turnover rates along river corridors. Per kilometer, low-order streams have a biogeochemical potential at least 2 orders of magnitude larger than higher-order streams. However, when biogeochemical potential is examined per average length of each stream order, low- and high-order streams were often found to be comparable. As a result, the hyporheic zone's intrinsic potential for biogeochemical transformations is comparable across different stream orders, but the greater river miles and larger total streambed area of lower order streams result in the highest cumulative impact from low-order streams. Lateral exchange through meander banks may be important in some cases but generally only in large rivers.

A hydrogeomorphic river network model predicts where and why hyporheic exchange is important in large basins

NASA Astrophysics Data System (ADS)

Gomez-Velez, Jesus D.; Harvey, Judson W.

2014-09-01

Hyporheic exchange has been hypothesized to have basin-scale consequences; however, predictions throughout river networks are limited by available geomorphic and hydrogeologic data and by models that can analyze and aggregate hyporheic exchange flows across large spatial scales. We developed a parsimonious but physically based model of hyporheic flow for application in large river basins: Networks with EXchange and Subsurface Storage (NEXSS). We applied NEXSS across a broad range of geomorphic diversity in river reaches and synthetic river networks. NEXSS demonstrates that vertical exchange beneath submerged bed forms rather than lateral exchange through meanders dominates hyporheic fluxes and turnover rates along river corridors. Per kilometer, low-order streams have a biogeochemical potential at least 2 orders of magnitude larger than higher-order streams. However, when biogeochemical potential is examined per average length of each stream order, low- and high-order streams were often found to be comparable. As a result, the hyporheic zone's intrinsic potential for biogeochemical transformations is comparable across different stream orders, but the greater river miles and larger total streambed area of lower order streams result in the highest cumulative impact from low-order streams. Lateral exchange through meander banks may be important in some cases but generally only in large rivers.

Are heritability and selection related to population size in nature? Meta-analysis and conservation implications.

PubMed

Wood, Jacquelyn L A; Yates, Matthew C; Fraser, Dylan J

2016-06-01

It is widely thought that small populations should have less additive genetic variance and respond less efficiently to natural selection than large populations. Across taxa, we meta-analytically quantified the relationship between adult census population size (N) and additive genetic variance (proxy: h (2)) and found no reduction in h (2) with decreasing N; surveyed populations ranged from four to one million individuals (1735 h (2) estimates, 146 populations, 83 species). In terms of adaptation, ecological conditions may systematically differ between populations of varying N; the magnitude of selection these populations experience may therefore also differ. We thus also meta-analytically tested whether selection changes with N and found little evidence for systematic differences in the strength, direction or form of selection with N across different trait types and taxa (7344 selection estimates, 172 populations, 80 species). Collectively, our results (i) indirectly suggest that genetic drift neither overwhelms selection more in small than in large natural populations, nor weakens adaptive potential/h (2) in small populations, and (ii) imply that natural populations of varying sizes experience a variety of environmental conditions, without consistently differing habitat quality at small N. However, we caution that the data are currently insufficient to determine whether some small populations may retain adaptive potential definitively. Further study is required into (i) selection and genetic variation in completely isolated populations of known N, under-represented taxonomic groups, and nongeneralist species, (ii) adaptive potential using multidimensional approaches and (iii) the nature of selective pressures for specific traits.

Effects of Baseline Levels of Flexibility and Vertical Jump Ability on Performance Following Different Volumes of Static Stretching and Potentiating Exercises in Elite Gymnasts

PubMed Central

Donti, Olyvia; Tsolakis, Charilaos; Bogdanis, Gregory C.

2014-01-01

This study examined the effects of baseline flexibility and vertical jump ability on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) following different volumes of stretching and potentiating exercises. ROM and CMJ were measured after two different warm-up protocols involving static stretching and potentiating exercises. Three groups of elite athletes (10 male, 14 female artistic gymnasts and 10 female rhythmic gymnasts) varying greatly in ROM and CMJ, performed two warm-up routines. One warm-up included short (15 s) static stretching followed by 5 tuck jumps, while the other included long static stretching (30 s) followed by 3x5 tuck jumps. ROM and CMJ were measured before, during and for 12 min after the two warm-up routines. Three-way ANOVA showed large differences between the three groups in baseline ROM and CMJ performance. A type of warm-up x time interaction was found for both ROM (p = 0.031) and CMJ (p = 0.016). However, all athletes, irrespective of group, responded in a similar fashion to the different warm-up protocols for both ROM and CMJ, as indicated from the lack of significant interactions for group (condition x group, time x group or condition x time x group). In the short warm-up protocol, ROM was not affected by stretching, while in the long warm-up protocol ROM increased by 5.9% ± 0.7% (p = 0.001) after stretching. Similarly, CMJ remained unchanged after the short warm-up protocol, but increased by 4.6 ± 0.9% (p = 0.012) 4 min after the long warm- up protocol, despite the increased ROM. It is concluded that the initial levels of flexibility and CMJ performance do not alter the responses of elite gymnasts to warm-up protocols differing in stretching and potentiating exercise volumes. Furthermore, 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance despite an increase in flexibility in these highly-trained athletes. Key Points The initial levels of flexibility and vertical jump ability have no effect on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) of elite gymnasts following warm-up protocols differing in stretching and potentiating exercise volumes Stretching of the main leg muscle groups for only 15 s has no effect on ROM of elite gymnasts In these highly-trained athletes, one set of 5 tuck jumps during warm-up is not adequate to increase CMJ performance, while 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance (by 4.6% above baseline), despite a 5.9% increase in flexibility due to the 30 s stretching exercises PMID:24570613

Numerical Simulations of Laminar Air-Water Flow of a Non-linear Progressive Wave at Low Wind Speed

NASA Astrophysics Data System (ADS)

Wen, X.; Mobbs, S.

2014-03-01

A numerical simulation for two-dimensional laminar air-water flow of a non-linear progressive water wave with large steepness is performed when the background wind speed varies from zero to the wave phase speed. It is revealed that in the water the difference between the analytical solution of potential flow and numerical solution of viscous flow is very small, indicating that both solutions of the potential flow and viscous flow describe the water wave very accurately. In the air the solutions of potential and viscous flows are very different due to the effects of viscosity. The velocity distribution in the airflow is strongly influenced by the background wind speed and it is found that three wind speeds, , (the maximum orbital velocity of a water wave), and (the wave phase speed), are important in distinguishing different features of the flow patterns.

Magnetic Susceptibility and Quantum Oscillations in a Buckled Honeycomb Lattice

NASA Astrophysics Data System (ADS)

Tabert, Calvin; Carbotte, Jules; Nicol, Elisabeth

2015-03-01

We calculate the magnetic response of a low-buckled honeycomb lattice with intrinsic spin-orbit coupling which is described by the Kane-Mele Hamiltonian (a model which would describe the low-energy physics of a material like silicene). Included in the Hamiltonian, is a sublattice potential difference term which may be induced by a perpendicular electric field; this field can tune the system from a topological insulator (TI), through a valley-spin polarized metal, to a trivial band insulator (BI). In an external magnetic field, a distinct signature of the phase transition is seen in the derivative of the magnetization with respect to chemical potential; this gives the quantization of the Hall plateaus through the Streda relation. The results are compared with the zero-frequency conductivity obtained from the Kubo formula. The magnetic susceptibility also displays signatures of the different topological phases. We also explore the de-Haas van-Alphen effect. At the transition point between the TI and BI, magnetic oscillations exist for any value of chemical potential. Away from the critical point, the chemical potential must be larger than the minimum gap. For large chemical potential (or small but finite sublattice potential difference), there is a strong beating pattern.

Organizational Trust in the Canadian Forces (La Confiance Organisationnelle dans les Forces Canadiennes)

DTIC Science & Technology

2008-03-01

potential differences in levels of trust between individualist and collectivist cultures . They collected survey data from 1,282 mid-level bank managers from...large banks in individualist cultures (Hawaii and Illinois) and in collectivist cultures ( South Korea, Japan, China, Taiwan, Hong Kong, and...organizational trust) than did people from collectivist cultures . No significant differences were found between cultures for intra-organizational trust

Adaptive Landscape Flattening Accelerates Sampling of Alchemical Space in Multisite λ Dynamics.

PubMed

Hayes, Ryan L; Armacost, Kira A; Vilseck, Jonah Z; Brooks, Charles L

2017-04-20

Multisite λ dynamics (MSλD) is a powerful emerging method in free energy calculation that allows prediction of relative free energies for a large set of compounds from very few simulations. Calculating free energy differences between substituents that constitute large volume or flexibility jumps in chemical space is difficult for free energy methods in general, and for MSλD in particular, due to large free energy barriers in alchemical space. This study demonstrates that a simple biasing potential can flatten these barriers and introduces an algorithm that determines system specific biasing potential coefficients. Two sources of error, deep traps at the end points and solvent disruption by hard-core potentials, are identified. Both scale with the size of the perturbed substituent and are removed by sharp biasing potentials and a new soft-core implementation, respectively. MSλD with landscape flattening is demonstrated on two sets of molecules: derivatives of the heat shock protein 90 inhibitor geldanamycin and derivatives of benzoquinone. In the benzoquinone system, landscape flattening leads to 2 orders of magnitude improvement in transition rates between substituents and robust solvation free energies. Landscape flattening opens up new applications for MSλD by enabling larger chemical perturbations to be sampled with improved precision and accuracy.

Long-distance abscisic acid signalling under different vertical soil moisture gradients depends on bulk root water potential and average soil water content in the root zone.

PubMed

Puértolas, Jaime; Alcobendas, Rosalía; Alarcón, Juan J; Dodd, Ian C

2013-08-01

To determine how root-to-shoot abscisic acid (ABA) signalling is regulated by vertical soil moisture gradients, root ABA concentration ([ABA](root)), the fraction of root water uptake from, and root water potential of different parts of the root zone, along with bulk root water potential, were measured to test various predictive models of root xylem ABA concentration [RX-ABA](sap). Beans (Phaseolus vulgaris L. cv. Nassau) were grown in soil columns and received different irrigation treatments (top and basal watering, and withholding water for varying lengths of time) to induce different vertical soil moisture gradients. Root water uptake was measured at four positions within the column by continuously recording volumetric soil water content (θv). Average θv was inversely related to bulk root water potential (Ψ(root)). In turn, Ψ(root) was correlated with both average [ABA](root) and [RX-ABA](sap). Despite large gradients in θv, [ABA](root) and root water potential was homogenous within the root zone. Consequently, unlike some split-root studies, root water uptake fraction from layers with different soil moisture did not influence xylem sap (ABA). This suggests two different patterns of ABA signalling, depending on how soil moisture heterogeneity is distributed within the root zone, which might have implications for implementing water-saving irrigation techniques. © 2013 John Wiley & Sons Ltd.

Cytogenetic effect of Alternanthera philoxeroides (alligator weed) on Agasicles hygrophila (Coleoptera: Chrysomelidae) in its native range

USDA-ARS?s Scientific Manuscript database

Plant polyploidy potentially affects plant-insect interactions; however, its effect on insect fitness remains largely unexplored. Alternanthera philoxeroides is a South American amphibious Amaranthaceae, which invades aquatic and terrestrial habitats. Different morphotypes and cytotypes were identif...

Complex dewetting scenarios of ultrathin silicon films for large-scale nanoarchitectures

PubMed Central

Naffouti, Meher; Backofen, Rainer; Salvalaglio, Marco; Bottein, Thomas; Lodari, Mario; Voigt, Axel; David, Thomas; Benkouider, Abdelmalek; Fraj, Ibtissem; Favre, Luc; Ronda, Antoine; Berbezier, Isabelle; Grosso, David; Abbarchi, Marco; Bollani, Monica

2017-01-01

Dewetting is a ubiquitous phenomenon in nature; many different thin films of organic and inorganic substances (such as liquids, polymers, metals, and semiconductors) share this shape instability driven by surface tension and mass transport. Via templated solid-state dewetting, we frame complex nanoarchitectures of monocrystalline silicon on insulator with unprecedented precision and reproducibility over large scales. Phase-field simulations reveal the dominant role of surface diffusion as a driving force for dewetting and provide a predictive tool to further engineer this hybrid top-down/bottom-up self-assembly method. Our results demonstrate that patches of thin monocrystalline films of metals and semiconductors share the same dewetting dynamics. We also prove the potential of our method by fabricating nanotransfer molding of metal oxide xerogels on silicon and glass substrates. This method allows the novel possibility of transferring these Si-based patterns on different materials, which do not usually undergo dewetting, offering great potential also for microfluidic or sensing applications. PMID:29296680

Complex dewetting scenarios of ultrathin silicon films for large-scale nanoarchitectures.

PubMed

Naffouti, Meher; Backofen, Rainer; Salvalaglio, Marco; Bottein, Thomas; Lodari, Mario; Voigt, Axel; David, Thomas; Benkouider, Abdelmalek; Fraj, Ibtissem; Favre, Luc; Ronda, Antoine; Berbezier, Isabelle; Grosso, David; Abbarchi, Marco; Bollani, Monica

2017-11-01

Dewetting is a ubiquitous phenomenon in nature; many different thin films of organic and inorganic substances (such as liquids, polymers, metals, and semiconductors) share this shape instability driven by surface tension and mass transport. Via templated solid-state dewetting, we frame complex nanoarchitectures of monocrystalline silicon on insulator with unprecedented precision and reproducibility over large scales. Phase-field simulations reveal the dominant role of surface diffusion as a driving force for dewetting and provide a predictive tool to further engineer this hybrid top-down/bottom-up self-assembly method. Our results demonstrate that patches of thin monocrystalline films of metals and semiconductors share the same dewetting dynamics. We also prove the potential of our method by fabricating nanotransfer molding of metal oxide xerogels on silicon and glass substrates. This method allows the novel possibility of transferring these Si-based patterns on different materials, which do not usually undergo dewetting, offering great potential also for microfluidic or sensing applications.

Recovery from the impact of light reduction on the seagrass Amphibolis griffithii, insights for dredging management.

PubMed

McMahon, Kathryn; Lavery, Paul S; Mulligan, Michael

2011-02-01

A large-scale, manipulative experiment was conducted to examine the extent and rate of recovery of meadows of the temperate Australian seagrass, Amphibolis griffithii to different light-reduction scenarios typical of dredging operations, and to identify potential indicators of recovery from light reduction stress. Shade cloth was used to mimic different intensities, durations and start times of light reduction, and then was removed to assess the recovery. The meadow could recover from 3 months of light stress (5-18% ambient) following 10 months re-exposure to ambient light, even when up to 72% of leaf biomass was lost, much faster recovery rates than has previously been observed for large seagrasses. However, when the meadow had been shaded for 6-9 months and more than 82% of leaf biomass was lost, no recovery was detected up to 23 months after the light stress had ceased, consistent with other studies. Five potential indicators of recovery were recommended. Copyright © 2010 Elsevier Ltd. All rights reserved.

Daily air temperature interpolated at high spatial resolution over a large mountainous region

USGS Publications Warehouse

Dodson, R.; Marks, D.

1997-01-01

Two methods are investigated for interpolating daily minimum and maximum air temperatures (Tmin and Tmax) at a 1 km spatial resolution over a large mountainous region (830 000 km2) in the U.S. Pacific Northwest. The methods were selected because of their ability to (1) account for the effect of elevation on temperature and (2) efficiently handle large volumes of data. The first method, the neutral stability algorithm (NSA), used the hydrostatic and potential temperature equations to convert measured temperatures and elevations to sea-level potential temperatures. The potential temperatures were spatially interpolated using an inverse-squared-distance algorithm and then mapped to the elevation surface of a digital elevation model (DEM). The second method, linear lapse rate adjustment (LLRA), involved the same basic procedure as the NSA, but used a constant linear lapse rate instead of the potential temperature equation. Cross-validation analyses were performed using the NSA and LLRA methods to interpolate Tmin and Tmax each day for the 1990 water year, and the methods were evaluated based on mean annual interpolation error (IE). The NSA method showed considerable bias for sites associated with vertical extrapolation. A correction based on climate station/grid cell elevation differences was developed and found to successfully remove the bias. The LLRA method was tested using 3 lapse rates, none of which produced a serious extrapolation bias. The bias-adjusted NSA and the 3 LLRA methods produced almost identical levels of accuracy (mean absolute errors between 1.2 and 1.3??C), and produced very similar temperature surfaces based on image difference statistics. In terms of accuracy, speed, and ease of implementation, LLRA was chosen as the best of the methods tested.

Post-genomic insights into the plant polysaccharide degradation potential of Aspergillus nidulans and comparison to Aspergillus niger and Aspergillus oryzae.

PubMed

Coutinho, Pedro M; Andersen, Mikael R; Kolenova, Katarina; vanKuyk, Patricia A; Benoit, Isabelle; Gruben, Birgit S; Trejo-Aguilar, Blanca; Visser, Hans; van Solingen, Piet; Pakula, Tiina; Seiboth, Bernard; Battaglia, Evy; Aguilar-Osorio, Guillermo; de Jong, Jan F; Ohm, Robin A; Aguilar, Mariana; Henrissat, Bernard; Nielsen, Jens; Stålbrand, Henrik; de Vries, Ronald P

2009-03-01

The plant polysaccharide degradative potential of Aspergillus nidulans was analysed in detail and compared to that of Aspergillus niger and Aspergillus oryzae using a combination of bioinformatics, physiology and transcriptomics. Manual verification indicated that 28.4% of the A. nidulans ORFs analysed in this study do not contain a secretion signal, of which 40% may be secreted through a non-classical method.While significant differences were found between the species in the numbers of ORFs assigned to the relevant CAZy families, no significant difference was observed in growth on polysaccharides. Growth differences were observed between the Aspergilli and Podospora anserina, which has a more different genomic potential for polysaccharide degradation, suggesting that large genomic differences are required to cause growth differences on polysaccharides. Differences were also detected between the Aspergilli in the presence of putative regulatory sequences in the promoters of the ORFs of this study and correlation of the presence of putative XlnR binding sites to induction by xylose was detected for A. niger. These data demonstrate differences at genome content, substrate specificity of the enzymes and gene regulation in these three Aspergilli, which likely reflect their individual adaptation to their natural biotope.

Distribution of Hydrocarbon-Utilizing Microorganisms and Hydrocarbon Biodegradation Potentials in Alaskan Continental Shelf Areas

PubMed Central

Roubal, George; Atlas, Ronald M.

1978-01-01

Hydrocarbon-utilizing microorganisms were enumerated from Alaskan continental shelf areas by using plate counts and a new most-probable-number procedure based on mineralization of 14C-labeled hydrocarbons. Hydrocarbon utilizers were ubiquitously distributed, with no significant overall concentration differences between sampling regions or between surface water and sediment samples. There were, however, significant seasonal differences in numbers of hydrocarbon utilizers. Distribution of hydrocarbon utilizers within Cook Inlet was positively correlated with occurrence of hydrocarbons in the environment. Hydrocarbon biodegradation potentials were measured by using 14C-radiolabeled hydrocarbon-spiked crude oil. There was no significant correlation between numbers of hydrocarbon utilizers and hydrocarbon biodegradation potentials. The biodegradation potentials showed large seasonal variations in the Beaufort Sea, probably due to seasonal depletion of available nutrients. Non-nutrient-limited biodegradation potentials followed the order hexadecane > naphthalene ≫ pristane > benzanthracene. In Cook Inlet, biodegradation potentials for hexadecane and naphthalene were dependent on availability of inorganic nutrients. Biodegradation potentials for pristane and benzanthracene were restricted, probably by resistance to attack by available enzymes in the indigenous population. PMID:655706

Expectations and reality for high latitude versus high elevation global change (Invited)

NASA Astrophysics Data System (ADS)

Bunn, A. G.; Lloyd, A. H.

2009-12-01

Arctic and alpine ecosystems are often treated as analogs of each other, in large part because they share a similar vegetation transition from forested to low-stature tundra communities. Despite the superficial similarities, the response of the two types of ecosystems to future climate change will likely differ because of differences in ecosystem history, function, and extent. The role of feedbacks differs substantially between the two as the Arctic terrestrial system is dominated by feedbacks which have the potential to significantly alter the rate and magnitude of future climate change. If invoked, these feedbacks will substantially alter and augment northern high latitude change far above the background forcing from increased greenhouse gas concentrations. The same is not obviously true for mountains, both because of the difference in areal extent and because of differences in soil characteristics that affect the potential for carbon cycle feedbacks. The climatic controls over biophysical processes may differ in subtle but important ways between the two systems despite the overriding importance of temperature as a control in both ecosystems. For example, changes in the position of the treeline ecotone in the Sierra Nevada during the late Holocene occurred in response to variation in both temperature and moisture, whereas treeline advance and retreat in Arctic regions appears to be primarily a function of temperature. Despite those differences, it appears likely that changes in Arctic and alpine ecosystems will have large influences on the global system. The consequences of changes in alpine ecosystems will be amplified by their large importance in controlling global water supplies. More than 50% of the world’s freshwater supplies, for example, are derived from mountainous regions. Any change to those regions might have disastrous effects on human welfare. Global impacts of changes in Arctic regions are amplified by the aforementioned feedbacks on the climate system, which have the potential to increase the rate of warming in high latitudes by several fold, with cascading effects on the global climate system. We will review some of the similarities and differences in arctic and alpine systems by showing data on predicted changes to the physical, floral, and faunal aspects of both systems paying particular attention to the role of feedbacks and forcings.

Isotopic Differences between Forage Consumed by a Large Herbivore in Open, Closed, and Coastal Habitats: New Evidence from a Boreal Study System.

PubMed

Giroux, Marie-Andrée; Valiquette, Éliane; Tremblay, Jean-Pierre; Côté, Steeve D

2015-01-01

Documenting habitat-related patterns in foraging behaviour at the individual level and over large temporal scales remains challenging for large herbivores. Stable isotope analysis could represent a valuable tool to quantify habitat-related foraging behaviour at the scale of individuals and over large temporal scales in forest dwelling large herbivores living in coastal environments, because the carbon (δ13C) or nitrogen (δ15N) isotopic signatures of forage can differ between open and closed habitats or between terrestrial and littoral forage, respectively. Here, we examined if we could detect isotopic differences between the different assemblages of forage taxa consumed by white-tailed deer that can be found in open, closed, supralittoral, and littoral habitats. We showed that δ13C of assemblages of forage taxa were 3.0 ‰ lower in closed than in open habitats, while δ15N were 2.0 ‰ and 7.4 ‰ higher in supralittoral and littoral habitats, respectively, than in terrestrial habitats. Stable isotope analysis may represent an additional technique for ecologists interested in quantifiying the consumption of terrestrial vs. marine autotrophs. Yet, given the relative isotopic proximity and the overlap between forage from open, closed, and supralittoral habitats, the next step would be to determine the potential to estimate their contribution to herbivore diet.

On the materials basis of modern society

PubMed Central

Graedel, T. E.; Nassar, N. T.; Reck, Barbara K.

2015-01-01

It is indisputable that modern life is enabled by the use of materials in its technologies. Those technologies do many things very well, largely because each material is used for purposes to which it is exquisitely fitted. The result over time has been a steady increase in product performance. We show that this materials complexity has markedly increased in the past half-century and that elemental life cycle analyses characterize rates of recycling and loss. A further concern is that of possible scarcity of some of the elements as their use increases. Should materials availability constraints occur, the use of substitute materials comes to mind. We studied substitution potential by generating a comprehensive summary of potential substitutes for 62 different metals in all their major uses and of the performance of the substitutes in those applications. As we show herein, for a dozen different metals, the potential substitutes for their major uses are either inadequate or appear not to exist at all. Further, for not 1 of the 62 metals are exemplary substitutes available for all major uses. This situation largely decouples materials substitution from price, thereby forcing material design changes to be primarily transformative rather than incremental. As wealth and population increase worldwide in the next few decades, scientists will be increasingly challenged to maintain and improve product utility by designing new and better materials, but doing so under potential constraints in resource availability. PMID:24297915

A Compendium of Transcriptomic Effects of Endocrine Disrupting Chemicals on the Fathead Minnow Ovary

EPA Science Inventory

Understanding potential hazards of chemicals released into the environment is challenging not only due to the large and growing number of chemicals and materials that need to be screened, but also to the bioavailability, exposure conditions, and species differences among others. ...

Copy number variation detection in cattle reveals potential breed specific differences

USDA-ARS?s Scientific Manuscript database

Copy Number Variations (CNVs) are large, common deletions or duplications of genome sequence among individuals of a species that have been linked to diseases and phenotypic traits. For example, a CNV-generating, translocation mechanism encompassing the KIT gene is responsible for color sidedness in ...

Antecedent conditions influence soil respiration differences in shrub and grass patches

USDA-ARS?s Scientific Manuscript database

Quantifying the response of soil respiration to past environmental conditions is critical for predicting how future climate and vegetation change will impact ecosystem carbon balance. Increased shrub dominance in semiarid grasslands has potentially large effects on soil carbon cycling. The goal of t...

Psychological Restoration Practices among College Students

ERIC Educational Resources Information Center

Altaher, Yara; Runnerstrom, Miryha G.

2018-01-01

This study investigates the restoration practices and the different types of environments sought out by college students during times of stress and also explores the potential for restorative experiences in built environments. In February 2015, 407 matriculated undergraduates at a large public research university voluntarily participated in this…

Cross-Cultural Analysis of E-Mail Reference

ERIC Educational Resources Information Center

Shachaf, Pnina; Meho, Lokman I.; Hara, Noriko

2007-01-01

Studies that examined virtual reference and its potential for collaboration have by and large represented experiences in western English-speaking countries. This article reports the results of a three-nation (Israel, Japan, and Lebanon) comparative analysis to bridge this research gap. Similarities and differences between these countries highlight…

Biospectroscopy reveals the effect of varying water quality on tadpole tissues of the common frog (Rana temporaria).

PubMed

Strong, Rebecca J; Halsall, Crispin J; Ferenčík, Martin; Jones, Kevin C; Shore, Richard F; Martin, Francis L

2016-06-01

Amphibians are undergoing large population declines in many regions around the world. As environmental pollution from both agricultural and urban sources has been implicated in such declines, there is a need for a biomonitoring approach to study potential impacts on this vulnerable class of organism. This study assessed the use of infrared (IR) spectroscopy as a tool to detect changes in several tissues (liver, muscle, kidney, heart and skin) of late-stage common frog (Rana temporaria) tadpoles collected from ponds with differing water quality. Small differences in spectral signatures were revealed between a rural agricultural pond and an urban pond receiving wastewater and landfill run-off; these were limited to the liver and heart, although large differences in body size were apparent, surprisingly with tadpoles from the urban site larger than those from the rural site. Large differences in liver spectra were found between tadpoles from the pesticide and nutrient impacted pond compared to the rural agricultural pond, particularly in regions associated with lipids. Liver mass and hepatosomatic indices were found to be significantly increased in tadpoles from the site impacted by pesticides and trace organic chemicals, suggestive of exposure to environmental contamination. Significant alterations were also found in muscle tissue between tadpoles from these two ponds in regions associated with glycogen, potentially indicative of a stress response. This study highlights the use of IR spectroscopy, a low-cost, rapid and reagent-free technique in the biomonitoring of a class of organisms susceptible to environmental degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Large Dog Relinquishment to Two Municipal Facilities in New York City and Washington, D.C.: Identifying Targets for Intervention

PubMed Central

Weiss, Emily; Slater, Margaret; Garrison, Laurie; Drain, Natasha; Dolan, Emily; Scarlett, Janet M.; Zawistowski, Stephen L.

2014-01-01

Simple Summary While the overall trend in euthanasia has been decreasing nationally, large dogs are at a higher risk of euthanasia than other-sized dogs in most animal shelters in the United States. We hypothesized that one way to increase the lives saved with regard to large dogs in shelters is to keep them home in the first place when possible. Our research is the first to collect data in New York City and Washington, D.C., identifying the process leading to the owner relinquishment of large dogs. We found that targets for interventions to decrease large dog relinquishment are likely different in each community. Abstract While the overall trend in euthanasia has been decreasing nationally, large dogs are at a higher risk of euthanasia than other sized dogs in most animal shelters in the United States. We hypothesized one way to increase the lives saved with respect to these large dogs is to keep them home when possible. In order to develop solutions to decrease relinquishment, a survey was developed to learn more about the reasons owners relinquish large dogs. The survey was administered to owners relinquishing their dogs at two large municipal facilities, one in New York City and one in Washington, D.C. There were 157 responses between the two facilities. We found both significant similarities and differences between respondents and their dogs from the two cities. We identified opportunities to potentially support future relinquishers and found that targets for interventions are likely different in each community. PMID:26480315

On Feature Extraction from Large Scale Linear LiDAR Data

NASA Astrophysics Data System (ADS)

Acharjee, Partha Pratim

Airborne light detection and ranging (LiDAR) can generate co-registered elevation and intensity map over large terrain. The co-registered 3D map and intensity information can be used efficiently for different feature extraction application. In this dissertation, we developed two algorithms for feature extraction, and usages of features for practical applications. One of the developed algorithms can map still and flowing waterbody features, and another one can extract building feature and estimate solar potential on rooftops and facades. Remote sensing capabilities, distinguishing characteristics of laser returns from water surface and specific data collection procedures provide LiDAR data an edge in this application domain. Furthermore, water surface mapping solutions must work on extremely large datasets, from a thousand square miles, to hundreds of thousands of square miles. National and state-wide map generation/upgradation and hydro-flattening of LiDAR data for many other applications are two leading needs of water surface mapping. These call for as much automation as possible. Researchers have developed many semi-automated algorithms using multiple semi-automated tools and human interventions. This reported work describes a consolidated algorithm and toolbox developed for large scale, automated water surface mapping. Geometric features such as flatness of water surface, higher elevation change in water-land interface and, optical properties such as dropouts caused by specular reflection, bimodal intensity distributions were some of the linear LiDAR features exploited for water surface mapping. Large-scale data handling capabilities are incorporated by automated and intelligent windowing, by resolving boundary issues and integrating all results to a single output. This whole algorithm is developed as an ArcGIS toolbox using Python libraries. Testing and validation are performed on a large datasets to determine the effectiveness of the toolbox and results are presented. Significant power demand is located in urban areas, where, theoretically, a large amount of building surface area is also available for solar panel installation. Therefore, property owners and power generation companies can benefit from a citywide solar potential map, which can provide available estimated annual solar energy at a given location. An efficient solar potential measurement is a prerequisite for an effective solar energy system in an urban area. In addition, the solar potential calculation from rooftops and building facades could open up a wide variety of options for solar panel installations. However, complex urban scenes make it hard to estimate the solar potential, partly because of shadows cast by the buildings. LiDAR-based 3D city models could possibly be the right technology for solar potential mapping. Although, most of the current LiDAR-based local solar potential assessment algorithms mainly address rooftop potential calculation, whereas building facades can contribute a significant amount of viable surface area for solar panel installation. In this paper, we introduce a new algorithm to calculate solar potential of both rooftop and building facades. Solar potential received by the rooftops and facades over the year are also investigated in the test area.

Performance of thermally-chargeable supercapacitors in different solvents.

PubMed

Lim, Hyuck; Zhao, Cang; Qiao, Yu

2014-07-07

The influence of solvent on the temperature sensitivity of the electrode potential of thermally-chargeable supercapacitors (TCSs) is investigated. For large electrodes, the output voltage is positively correlated with the dielectric constant of solvent. When nanoporous carbon electrodes are used, different characteristics of system performance are observed, suggesting that possible size effects must be taken into consideration when the solvent molecules and solvated ions are confined in a nanoenvironment.

Quantifying the potential for reservoirs to secure future surface water yields in the world’s largest river basins

NASA Astrophysics Data System (ADS)

Liu, Lu; Parkinson, Simon; Gidden, Matthew; Byers, Edward; Satoh, Yusuke; Riahi, Keywan; Forman, Barton

2018-04-01

Surface water reservoirs provide us with reliable water supply, hydropower generation, flood control and recreation services. Yet reservoirs also cause flow fragmentation in rivers and lead to flooding of upstream areas, thereby displacing existing land-use activities and ecosystems. Anticipated population growth and development coupled with climate change in many regions of the globe suggests a critical need to assess the potential for future reservoir capacity to help balance rising water demands with long-term water availability. Here, we assess the potential of large-scale reservoirs to provide reliable surface water yields while also considering environmental flows within 235 of the world’s largest river basins. Maps of existing cropland and habitat conservation zones are integrated with spatially-explicit population and urbanization projections from the Shared Socioeconomic Pathways to identify regions unsuitable for increasing water supply by exploiting new reservoir storage. Results show that even when maximizing the global reservoir storage to its potential limit (∼4.3–4.8 times the current capacity), firm yields would only increase by about 50% over current levels. However, there exist large disparities across different basins. The majority of river basins in North America are found to gain relatively little firm yield by increasing storage capacity, whereas basins in Southeast Asia display greater potential for expansion as well as proportional gains in firm yield under multiple uncertainties. Parts of Europe, the United States and South America show relatively low reliability of maintaining current firm yields under future climate change, whereas most of Asia and higher latitude regions display comparatively high reliability. Findings from this study highlight the importance of incorporating different factors, including human development, land-use activities, and climate change, over a time span of multiple decades and across a range of different scenarios when quantifying available surface water yields and the potential for reservoir expansion.

Routine health insurance data for scientific research: potential and limitations of the Agis Health Database.

PubMed

Smeets, Hugo M; de Wit, Niek J; Hoes, Arno W

2011-04-01

Observational studies performed within routine health care databases have the advantage of their large size and, when the aim is to assess the effect of interventions, can offer a completion to randomized controlled trials with usually small samples from experimental situations. Institutional Health Insurance Databases (HIDs) are attractive for research because of their large size, their longitudinal perspective, and their practice-based information. As they are based on financial reimbursement, the information is generally reliable. The database of one of the major insurance companies in the Netherlands, the Agis Health Database (AHD), is described in detail. Whether the AHD data sets meet the specific requirements to conduct several types of clinical studies is discussed according to the classification of the four different types of clinical research; that is, diagnostic, etiologic, prognostic, and intervention research. The potential of the AHD for these various types of research is illustrated using examples of studies recently conducted in the AHD. HIDs such as the AHD offer large potential for several types of clinical research, in particular etiologic and intervention studies, but at present the lack of detailed clinical information is an important limitation. Copyright © 2011 Elsevier Inc. All rights reserved.

Finite Difference Time Marching in the Frequency Domain: A Parabolic Formulation for the Convective Wave Equation

NASA Technical Reports Server (NTRS)

Baumeister, K. J.; Kreider, K. L.

1996-01-01

An explicit finite difference iteration scheme is developed to study harmonic sound propagation in ducts. To reduce storage requirements for large 3D problems, the time dependent potential form of the acoustic wave equation is used. To insure that the finite difference scheme is both explicit and stable, time is introduced into the Fourier transformed (steady-state) acoustic potential field as a parameter. Under a suitable transformation, the time dependent governing equation in frequency space is simplified to yield a parabolic partial differential equation, which is then marched through time to attain the steady-state solution. The input to the system is the amplitude of an incident harmonic sound source entering a quiescent duct at the input boundary, with standard impedance boundary conditions on the duct walls and duct exit. The introduction of the time parameter eliminates the large matrix storage requirements normally associated with frequency domain solutions, and time marching attains the steady-state quickly enough to make the method favorable when compared to frequency domain methods. For validation, this transient-frequency domain method is applied to sound propagation in a 2D hard wall duct with plug flow.

The Immunologic Basis for Severe Neonatal Herpes Disease and Potential Strategies for Therapeutic Intervention

PubMed Central

Gantt, Soren; Muller, William J.

2013-01-01

Herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2) infect a large proportion of the world's population. Infection is life-long and can cause periodic mucocutaneous symptoms, but it only rarely causes life-threatening disease among immunocompetent children and adults. However, when HSV infection occurs during the neonatal period, viral replication is poorly controlled and a large proportion of infants die or develop disability even with optimal antiviral therapy. Increasingly, specific differences are being elucidated between the immune system of newborns and those of older children and adults, which predispose to severe infections and reflect the transition from fetal to postnatal life. Studies in healthy individuals of different ages, individuals with primary or acquired immunodeficiencies, and animal models have contributed to our understanding of the mechanisms that control HSV infection and how these may be impaired during the neonatal period. This paper outlines our current understanding of innate and adaptive immunity to HSV infection, immunologic differences in early infancy that may account for the manifestations of neonatal HSV infection, and the potential of interventions to augment neonatal immune protection against HSV disease. PMID:23606868

Finite Difference Time Marching in the Frequency Domain: A Parabolic Formulation for Aircraft Acoustic Nacelle Design

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Kreider, Kevin L.

1996-01-01

An explicit finite difference iteration scheme is developed to study harmonic sound propagation in aircraft engine nacelles. To reduce storage requirements for large 3D problems, the time dependent potential form of the acoustic wave equation is used. To insure that the finite difference scheme is both explicit and stable, time is introduced into the Fourier transformed (steady-state) acoustic potential field as a parameter. Under a suitable transformation, the time dependent governing equation in frequency space is simplified to yield a parabolic partial differential equation, which is then marched through time to attain the steady-state solution. The input to the system is the amplitude of an incident harmonic sound source entering a quiescent duct at the input boundary, with standard impedance boundary conditions on the duct walls and duct exit. The introduction of the time parameter eliminates the large matrix storage requirements normally associated with frequency domain solutions, and time marching attains the steady-state quickly enough to make the method favorable when compared to frequency domain methods. For validation, this transient-frequency domain method is applied to sound propagation in a 2D hard wall duct with plug flow.

An eigenfunction method for reconstruction of large-scale and high-contrast objects.

PubMed

Waag, Robert C; Lin, Feng; Varslot, Trond K; Astheimer, Jeffrey P

2007-07-01

A multiple-frequency inverse scattering method that uses eigenfunctions of a scattering operator is extended to image large-scale and high-contrast objects. The extension uses an estimate of the scattering object to form the difference between the scattering by the object and the scattering by the estimate of the object. The scattering potential defined by this difference is expanded in a basis of products of acoustic fields. These fields are defined by eigenfunctions of the scattering operator associated with the estimate. In the case of scattering objects for which the estimate is radial, symmetries in the expressions used to reconstruct the scattering potential greatly reduce the amount of computation. The range of parameters over which the reconstruction method works well is illustrated using calculated scattering by different objects. The method is applied to experimental data from a 48-mm diameter scattering object with tissue-like properties. The image reconstructed from measurements has, relative to a conventional B-scan formed using a low f-number at the same center frequency, significantly higher resolution and less speckle, implying that small, high-contrast structures can be demonstrated clearly using the extended method.

Electrostatic screening in classical Coulomb fluids: exponential or power-law decay or both? An investigation into the effect of dispersion interactions

NASA Astrophysics Data System (ADS)

Kjellander, Roland

2006-04-01

It is shown that the nature of the non-electrostatic part of the pair interaction potential in classical Coulomb fluids can have a profound influence on the screening behaviour. Two cases are compared: (i) when the non-electrostatic part equals an arbitrary finite-ranged interaction and (ii) when a dispersion r-6 interaction potential is included. A formal analysis is done in exact statistical mechanics, including an investigation of the bridge function. It is found that the Coulombic r-1 and the dispersion r-6 potentials are coupled in a very intricate manner as regards the screening behaviour. The classical one-component plasma (OCP) is a particularly clear example due to its simplicity and is investigated in detail. When the dispersion r-6 potential is turned on, the screened electrostatic potential from a particle goes from a monotonic exponential decay, exp(-κr)/r, to a power-law decay, r-8, for large r. The pair distribution function acquire, at the same time, an r-10 decay for large r instead of the exponential one. There still remains exponentially decaying contributions to both functions, but these contributions turn oscillatory when the r-6 interaction is switched on. When the Coulomb interaction is turned off but the dispersion r-6 pair potential is kept, the decay of the pair distribution function for large r goes over from the r-10 to an r-6 behaviour, which is the normal one for fluids of electroneutral particles with dispersion interactions. Differences and similarities compared to binary electrolytes are pointed out.

Effect of silhouette color on trap catches of Dendroctonus frontalis (Coleoptera: Scolytidae)

Treesearch

B.L. Strom; R.A. Goyer

2001-01-01

With the exception of responses to semiochemicals, host selection behaviors of D. frontalis are largely unstudied. To better understand the host finding behavior of D. frontalis, and to identify potential visual disruptants, we evaluated the response of D. frontalis to multiple-funnel traps of eight different...

Tracking Women's Transitions to Adulthood: Race, Curricular Tracking, and Young Adult Outcomes

ERIC Educational Resources Information Center

Beattie, Irenee R.

2017-01-01

Theories suggest curricular tracking is linked to racial/ethnic inequality. However, prior studies largely examine cognitive outcomes like standardized test scores and neglect behavioral outcomes. They also overlook potential racial/ethnic differences "within" curricular tracks. This study asks the following questions: (a) Is curricular…

Enriching Later Life through Higher Education: Profiting from International Experience

ERIC Educational Resources Information Center

Ring, Chris; De Motte, Claire

2016-01-01

Developed countries differ greatly in their policy response to population ageing. In the United Kingdom, little attention is given to its positive features, and the potential of lifelong learning to enhance the wellbeing of older populations is largely disregarded. Universities have increasingly neglected them, while expanding provision for much…

Population differentiation in Pacific salmon: local adaptation, genetic drift, or the environment?

USGS Publications Warehouse

Adkison, Milo D.

1995-01-01

Morphological, behavioral, and life-history differences between Pacific salmon (Oncorhynchus spp.) populations are commonly thought to reflect local adaptation, and it is likewise common to assume that salmon populations separated by small distances are locally adapted. Two alternatives to local adaptation exist: random genetic differentiation owing to genetic drift and founder events, and genetic homogeneity among populations, in which differences reflect differential trait expression in differing environments. Population genetics theory and simulations suggest that both alternatives are possible. With selectively neutral alleles, genetic drift can result in random differentiation despite many strays per generation. Even weak selection can prevent genetic drift in stable populations; however, founder effects can result in random differentiation despite selective pressures. Overlapping generations reduce the potential for random differentiation. Genetic homogeneity can occur despite differences in selective regimes when straying rates are high. In sum, localized differences in selection should not always result in local adaptation. Local adaptation is favored when population sizes are large and stable, selection is consistent over large areas, selective diffeentials are large, and straying rates are neither too high nor too low. Consideration of alternatives to local adaptation would improve both biological research and salmon conservation efforts.

Experimental evidence for herbivore limitation of the treeline.

PubMed

Speed, James D M; Austrheim, Gunnar; Hester, Alison J; Mysterud, Atle

2010-11-01

The treeline ecotone divides forest from open alpine or arctic vegetation states. Treelines are generally perceived to be temperature limited. The role of herbivores in limiting the treeline is more controversial, as experimental evidence from relevant large scales is lacking. Here we quantify the impact of different experimentally controlled herbivore densities on the recruitment and survival of birch Betula pubescens tortuosa along an altitudinal gradient in the mountains of southern Norway. After eight years of summer grazing in large-scale enclosures at densities of 0, 25, and 80 sheep/km2, birch recruited within the whole altitudinal range of ungrazed enclosures, but recruitment was rarer in enclosures with low-density sheep and was largely limited to within the treeline in enclosures with high-density sheep. In contrast, the distribution of saplings (birch older than the experiment) did not differ between grazing treatments, suggesting that grazing sheep primarily limit the establishment of new tree recruits rather than decrease the survival of existing individuals. This study provides direct experimental evidence that herbivores can limit the treeline below its potential at the landscape scale and even at low herbivore densities in this climatic zone. Land use changes should thus be considered in addition to climatic changes as potential drivers of ecotone shifts.

Characterizing large river sounds: Providing context for understanding the environmental effects of noise produced by hydrokinetic turbines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bevelhimer, Mark S.; Deng, Z. Daniel; Scherelis, Constantin

2016-01-01

Underwater noise associated with the installation and operation of hydrokinetic turbines in rivers and tidal zones presents a potential environmental concern for fish and marine mammals. Comparing the spectral quality of sounds emitted by hydrokinetic turbines to natural and other anthropogenic sound sources is an initial step at understanding potential environmental impacts. Underwater recordings were obtained from passing vessels of different sizes and other underwater sound sources in both static and flowing waters. Static water measurements were taken in a lake with minimal background noise. Flowing water measurements were taken at a previously proposed deployment site for hydrokinetic turbines onmore » the Mississippi River, where the sound of flowing water is included in background measurements. The size of vessels measured ranged from a small fishing boat with a 60 HP outboard motor to an 18-unit barge train being pushed upstream by tugboat. As expected, large vessels with large engines created the highest sound levels, and when compared to the sound created by an operating HK turbine were many times greater. A comparison of sound levels from the same sources at different distances using both spherical and cylindrical sound attenuation functions suggests that spherical model results more closely approximate observed values.« less

Simulation studies for surfaces and materials strength

NASA Technical Reports Server (NTRS)

Halicioglu, Timur

1987-01-01

A realistic potential energy function comprising angle dependent terms was employed to describe the potential surface of the N+O2 system. The potential energy parameters were obtained from high level ab-initio results using a nonlinear fitting procedure. It was shown that the potential function is able to reproduce a large number of points on the potential surface with a small rms deviation. A literature survey was conducted to analyze exclusively the status of current small cluster research. This survey turned out to be quite useful in understanding and finding out the existing relationship between theoretical as well as experimental investigative techniques employed by different researchers. Additionally, the importance of the role played by computer simulation in small cluster research, was documented.

Adsorbed molecules in external fields: Effect of confining potential

NASA Astrophysics Data System (ADS)

Tyagi, Ashish; Silotia, Poonam; Maan, Anjali; Prasad, Vinod

2016-12-01

We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials.

Avoiding 100 New Power Plants by Increasing Efficiency of Room Air Conditioners in India: Opportunities and Challenges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phadke, Amol; Abhyankar, Nikit; Shah, Nihar

Electricity demand for room ACs is growing very rapidly in emerging economies such as India. We estimate the electricity demand from room ACs in 2030 in India considering factors such as weather and income growth using market data on penetration of ACs in different income classes and climatic regions. We discuss the status of the current standards, labels, and incentive programs to improve the efficiency of room ACs in these markets and assess the potential for further large improvements in efficiency and find that efficiency can be improved by over 40percent cost effectively. The total potential energy savings from Roommore » AC efficiency improvement in India using the best available technology will reach over 118 TWh in 2030; potential peak demand saving is found to be 60 GW by 2030. This is equivalent to avoiding 120 new coal fired power plants of 500 MW each. We discuss policy options to complement, expand and improve the ongoing programs to capture this large potential.« less

How to derive biological information from the value of the normalization constant in allometric equations.

PubMed

Kaitaniemi, Pekka

2008-04-09

Allometric equations are widely used in many branches of biological science. The potential information content of the normalization constant b in allometric equations of the form Y = bX(a) has, however, remained largely neglected. To demonstrate the potential for utilizing this information, I generated a large number of artificial datasets that resembled those that are frequently encountered in biological studies, i.e., relatively small samples including measurement error or uncontrolled variation. The value of X was allowed to vary randomly within the limits describing different data ranges, and a was set to a fixed theoretical value. The constant b was set to a range of values describing the effect of a continuous environmental variable. In addition, a normally distributed random error was added to the values of both X and Y. Two different approaches were then used to model the data. The traditional approach estimated both a and b using a regression model, whereas an alternative approach set the exponent a at its theoretical value and only estimated the value of b. Both approaches produced virtually the same model fit with less than 0.3% difference in the coefficient of determination. Only the alternative approach was able to precisely reproduce the effect of the environmental variable, which was largely lost among noise variation when using the traditional approach. The results show how the value of b can be used as a source of valuable biological information if an appropriate regression model is selected.

The potential impact of immunization campaign budget re-allocation on global eradication of paediatric infectious diseases

PubMed Central

2011-01-01

Background The potential benefits of coordinating infectious disease eradication programs that use campaigns such as supplementary immunization activities (SIAs) should not be over-looked. One example of a coordinated approach is an adaptive "sequential strategy": first, all annual SIA budget is dedicated to the eradication of a single infectious disease; once that disease is eradicated, the annual SIA budget is re-focussed on eradicating a second disease, etc. Herd immunity suggests that a sequential strategy may eradicate several infectious diseases faster than a non-adaptive "simultaneous strategy" of dividing annual budget equally among eradication programs for those diseases. However, mathematical modeling is required to understand the potential extent of this effect. Methods Our objective was to illustrate how budget allocation strategies can interact with the nonlinear nature of disease transmission to determine time to eradication of several infectious diseases under different budget allocation strategies. Using a mathematical transmission model, we analyzed three hypothetical vaccine-preventable infectious diseases in three different countries. A central decision-maker can distribute funding among SIA programs for these three diseases according to either a sequential strategy or a simultaneous strategy. We explored the time to eradication under these two strategies under a range of scenarios. Results For a certain range of annual budgets, all three diseases can be eradicated relatively quickly under the sequential strategy, whereas eradication never occurs under the simultaneous strategy. However, moderate changes to total SIA budget, SIA frequency, order of eradication, or funding disruptions can create disproportionately large differences in the time and budget required for eradication under the sequential strategy. We find that the predicted time to eradication can be very sensitive to small differences in the rate of case importation between the countries. We also find that the time to eradication of all three diseases is not necessarily lowest when the least transmissible disease is targeted first. Conclusions Relatively modest differences in budget allocation strategies in the near-term can result in surprisingly large long-term differences in time required to eradicate, as a result of the amplifying effects of herd immunity and the nonlinearities of disease transmission. More sophisticated versions of such models may be useful to large international donors or other organizations as a planning or portfolio optimization tool, where choices must be made regarding how much funding to dedicate to different infectious disease eradication efforts. PMID:21955853

The potential impact of immunization campaign budget re-allocation on global eradication of paediatric infectious diseases.

PubMed

Fitzpatrick, Tiffany; Bauch, Chris T

2011-09-28

The potential benefits of coordinating infectious disease eradication programs that use campaigns such as supplementary immunization activities (SIAs) should not be over-looked. One example of a coordinated approach is an adaptive "sequential strategy": first, all annual SIA budget is dedicated to the eradication of a single infectious disease; once that disease is eradicated, the annual SIA budget is re-focussed on eradicating a second disease, etc. Herd immunity suggests that a sequential strategy may eradicate several infectious diseases faster than a non-adaptive "simultaneous strategy" of dividing annual budget equally among eradication programs for those diseases. However, mathematical modeling is required to understand the potential extent of this effect. Our objective was to illustrate how budget allocation strategies can interact with the nonlinear nature of disease transmission to determine time to eradication of several infectious diseases under different budget allocation strategies. Using a mathematical transmission model, we analyzed three hypothetical vaccine-preventable infectious diseases in three different countries. A central decision-maker can distribute funding among SIA programs for these three diseases according to either a sequential strategy or a simultaneous strategy. We explored the time to eradication under these two strategies under a range of scenarios. For a certain range of annual budgets, all three diseases can be eradicated relatively quickly under the sequential strategy, whereas eradication never occurs under the simultaneous strategy. However, moderate changes to total SIA budget, SIA frequency, order of eradication, or funding disruptions can create disproportionately large differences in the time and budget required for eradication under the sequential strategy. We find that the predicted time to eradication can be very sensitive to small differences in the rate of case importation between the countries. We also find that the time to eradication of all three diseases is not necessarily lowest when the least transmissible disease is targeted first. Relatively modest differences in budget allocation strategies in the near-term can result in surprisingly large long-term differences in time required to eradicate, as a result of the amplifying effects of herd immunity and the nonlinearities of disease transmission. More sophisticated versions of such models may be useful to large international donors or other organizations as a planning or portfolio optimization tool, where choices must be made regarding how much funding to dedicate to different infectious disease eradication efforts.

Potential Analysis of Rainfall-induced Sediment Disaster

NASA Astrophysics Data System (ADS)

Chen, Jing-Wen; Chen, Yie-Ruey; Hsieh, Shun-Chieh; Tsai, Kuang-Jung; Chue, Yung-Sheng

2014-05-01

Most of the mountain regions in Taiwan are sedimentary and metamorphic rocks which are fragile and highly weathered. Severe erosion occurs due to intensive rainfall and rapid flow, the erosion is even worsen by frequent earthquakes and severely affects the stability of hillsides. Rivers are short and steep in Taiwan with large runoff differences in wet and dry seasons. Discharges respond rapidly with rainfall intensity and flood flows usually carry large amount of sediment. Because of the highly growth in economics and social change, the development in the slope land is inevitable in Taiwan. However, sediment disasters occur frequently in high and precipitous region during typhoon. To make the execution of the regulation of slope land development more efficiency, construction of evaluation model for sediment potential is very important. In this study, the Genetic Adaptive Neural Network (GANN) was implemented in texture analysis techniques for the classification of satellite images of research region before and after typhoon or extreme rainfall and to obtain surface information and hazard log data. By using GANN weight analysis, factors, levels and probabilities of disaster of the research areas are presented. Then, through geographic information system the disaster potential map is plotted to distinguish high potential regions from low potential regions. Finally, the evaluation processes for sediment disaster after rainfall due to slope land use are established. In this research, the automatic image classification and evaluation modules for sediment disaster after rainfall due to slope land disturbance and natural environment are established in MATLAB to avoid complexity and time of computation. After implementation of texture analysis techniques, the results show that the values of overall accuracy and coefficient of agreement of the time-saving image classification for different time periods are at intermediate-high level and above. The results of GANN show that the weight of building density is the largest in all slope land disturbance factors, followed by road density, orchard density, baren land density, vegetation density, and farmland density. The weight of geology is the largest in all natural environment factors, followed by slope roughness, slope, and elevation. Overlaying the locations of large sediment disaster in the past on the potential map predicted by GANN, we found that most damage areas were in the region with medium-high or high potential of landslide. Therefore, the proposed potential model of sediment disaster can be used in practice.

Modelling dispersal of radioactive contaminants in Arctic waters as a result of potential recovery operations on the dumped submarine K-27.

PubMed

Karcher, M; Hosseini, A; Schnur, R; Kauker, F; Brown, J E; Dowdall, M; Strand, P

2017-03-15

Of the wide variety of dumped objects containing radioactive materials in the Arctic seas, the submarine K-27 constitutes a major risk due to the large amount of highly enriched uranium onboard and its location in shallow waters. As the matter of potential operations involving raising of the submarine have entered the public arena, a priori assessment of the contamination in the Arctic marine environment that could result after a possible accident during such operations is a matter of some interest. The dispersion of contaminants within the Arctic has been assessed using a large scale hydrodynamic model for a series of plausible accident scenarios and locations under different oceanographic regimes. Results indicate that, depending primarily on the nature of a release (i.e. instantaneous or continuous), large areas of the Arctic marine environment will exhibit contamination to varying degrees. Copyright © 2017 Elsevier Ltd. All rights reserved.

Role of rasagiline in treating Parkinson's disease: Effect on disease progression.

PubMed

Malaty, Irene A; Fernandez, Hubert H

2009-08-01

Rasagiline is a second generation, selective, irreversible monoamine oxidase type B (MAO-B) inhibitor. It has demonstrated efficacy in monotherapy for early Parkinson's disease (PD) patients in one large randomized, placebo-controlled trial (TVP-1012 in Early Monotherapy for Parkinson's Disease Outpatients), and has shown ability to reduce off time in more advanced PD patients with motor fluctuations in two large placebo-controlled trials (Parkinson's Rasagiline: Efficacy and Safety in the Treatment of "Off", and Lasting Effect in Adjunct Therapy With Rasagiline Given Once Daily). Preclinical data abound to suggest potential for neuroprotection by this compound against a variety of neurotoxic insults in cell cultures and in animals. The lack of amphetamine metabolites provides an advantage over the first generation MAO-B inhibitor selegiline. One large trial has investigated the potential for disease modification in PD patients (Attenuation of Disease progression with Azilect Given Once-daily) and preliminary results maintain some possible advantage to earlier initiation of the 1 mg/day dose. The clinical significance of the difference detected remains a consideration.

Seaweeds from the Portuguese coast: A potential food resource?

NASA Astrophysics Data System (ADS)

Soares, C.; Machado, S.; Vieira, E. F.; Morais, S.; Teles, M. T.; Correia, M.; Carvalho, A.; Domingues, V. F.; Ramalhosa, M. J.; Delerue-Matos, C.; Antunes, F.

2017-09-01

The Portuguese coast presents a large amount of potentially edible seaweeds that are underexploited. The identification of different macroalgae species and their availability in the northern and central coast of the continental territory was assessed. The nutritional value of seaweeds is discussed based on a literature review (when available) focused on data for species collected in Portugal with the aim to define the most important nutritional parameters that should be characterized in the samples. Possible health concerns related with the presence of contaminants are also considered.

Increased tornado hazard in large metropolitan areas

NASA Astrophysics Data System (ADS)

Cusack, Stephen

2014-11-01

The tornado climate was compared between large metropolitan areas and neighbouring non-metro cities using modern tornado reports in the Storm Prediction Center (SPC) archives. Twenty large metro areas in the higher-risk region of the U.S. were used to boost sample sizes hence robustness of results. Observational biases were minimised by using the most densely populated zips. The analysis found 50% greater tornado frequency and a thicker-tailed severity distribution in metro areas compared to the non-metro cities. These differences are significant at the 1% level. Regarding tornado frequency, the primary question is whether the raised occurrence rates in metro areas are due to observation biases or real differences in tornado climate. Past studies found no relative biases at the population densities used here, whereas there are two potential urban drivers of tornadogenesis. First, the urban heat island raises the storm severity above and downwind of main urban areas, as recorded in precipitation and lightning datasets. Second, the increased surface roughness over metro areas raises low-level shear which in turn has been found to be favourable for tornadogenesis. Modification of convective storms over large metro areas is the more plausible explanation of raised tornado frequency. The drivers of a thicker-tailed tornado severity distribution in metro areas are less certain. Potential causes include: increased debris-loading in metro tornadoes; modification of storms' lower boundary layer by increased surface roughness in metro areas; the reduced density of damage indicators in non-metro cities.

Small lakes show muted climate change signal in deepwater temperatures

USGS Publications Warehouse

Winslow, Luke A.; Read, Jordan S.; Hansen, Gretchen J. A.; Hanson, Paul C.

2015-01-01

Water temperature observations were collected from 142 lakes across Wisconsin, USA, to examine variation in temperature of lakes exposed to similar regional climate. Whole lake water temperatures increased across the state from 1990 to 2012, with an average trend of 0.042°C yr−1 ± 0.01°C yr−1. In large (>0.5 km2) lakes, the positive temperature trend was similar across all depths. In small lakes (<0.5 km2), the warming trend was restricted to shallow waters, with no significant temperature trend observed in water >0.5 times the maximum lake depth. The differing response of small versus large lakes is potentially a result of wind-sheltering reducing turbulent mixing magnitude in small lakes. These results demonstrate that small lakes respond differently to climate change than large lakes, suggesting that current predictions of impacts to lakes from climate change may require modification.

QCD dirac operator at nonzero chemical potential: lattice data and matrix model.

PubMed

Akemann, Gernot; Wettig, Tilo

2004-03-12

Recently, a non-Hermitian chiral random matrix model was proposed to describe the eigenvalues of the QCD Dirac operator at nonzero chemical potential. This matrix model can be constructed from QCD by mapping it to an equivalent matrix model which has the same symmetries as QCD with chemical potential. Its microscopic spectral correlations are conjectured to be identical to those of the QCD Dirac operator. We investigate this conjecture by comparing large ensembles of Dirac eigenvalues in quenched SU(3) lattice QCD at a nonzero chemical potential to the analytical predictions of the matrix model. Excellent agreement is found in the two regimes of weak and strong non-Hermiticity, for several different lattice volumes.

Energy efficiency in the U.S. residential sector: An engineering and economic assessment of opportunities for large energy savings and greenhouse gas emissions reductions

NASA Astrophysics Data System (ADS)

Lima de Azevedo, Ines Margarida

Energy efficiency and conservation is a very promising part of a portfolio of the needed strategies to mitigate climate change. Several technologies and energy efficiency measures in the residential sector offer potential for large energy savings. However, while energy efficiency options are currently considered as a means of reducing carbon emissions, there is still large uncertainty about the effect of such measures on overall carbon savings. The first part of this thesis provides a national assessment of the energy efficiency potential in the residential sector under several different scenarios, which include the perspectives of different economic agents (consumers, utilities, ESCOs, and a society). The scenarios also include maximizing energy, electricity or carbon dioxide savings. The second part of this thesis deals with a detailed assessment of the potential for white-light LEDs for energy and carbon dioxide savings in the U.S. commercial and residential sectors. Solid-state lighting shows great promise as a source of efficient, affordable, color-balanced white light. Indeed, assuming market discount rates, the present work demonstrates that white solid-state lighting already has a lower levelized annual cost (LAC) than incandescent bulbs and that it will be lower than that of the most efficient fluorescent bulbs by the end of this decade. However, a large literature indicates that households do not make their decisions in terms of simple expected economic value. The present analysis shows that incorporating the findings from literature on high implicit discount rates from households when performing decisions towards efficient technologies delays the adoption of white LEDs by a couple of years. After a review of the technology, the present work compares the electricity consumption, carbon emissions and cost-effectiveness of current lighting technologies, when accounting for expected performance evolution through 2015. Simulations of lighting electricity consumption and implicit greenhouse gases emissions for the U.S. residential and commercial sectors through 2015 under different policy scenarios (voluntary solid-state lighting adoption, implementation of lighting standards in new construction and rebate programs or equivalent subsidies) are also included.

Geodetic methods to determine the relativistic redshift at the level of 10^{-18} in the context of international timescales: a review and practical results

NASA Astrophysics Data System (ADS)

Denker, Heiner; Timmen, Ludger; Voigt, Christian; Weyers, Stefan; Peik, Ekkehard; Margolis, Helen S.; Delva, Pacôme; Wolf, Peter; Petit, Gérard

2017-12-01

The frequency stability and uncertainty of the latest generation of optical atomic clocks is now approaching the one part in 10^{18} level. Comparisons between earthbound clocks at rest must account for the relativistic redshift of the clock frequencies, which is proportional to the corresponding gravity (gravitational plus centrifugal) potential difference. For contributions to international timescales, the relativistic redshift correction must be computed with respect to a conventional zero potential value in order to be consistent with the definition of Terrestrial Time. To benefit fully from the uncertainty of the optical clocks, the gravity potential must be determined with an accuracy of about 0.1 m2 s^{-2} , equivalent to about 0.01 m in height. This contribution focuses on the static part of the gravity field, assuming that temporal variations are accounted for separately by appropriate reductions. Two geodetic approaches are investigated for the derivation of gravity potential values: geometric levelling and the Global Navigation Satellite Systems (GNSS)/geoid approach. Geometric levelling gives potential differences with millimetre uncertainty over shorter distances (several kilometres), but is susceptible to systematic errors at the decimetre level over large distances. The GNSS/geoid approach gives absolute gravity potential values, but with an uncertainty corresponding to about 2 cm in height. For large distances, the GNSS/geoid approach should therefore be better than geometric levelling. This is demonstrated by the results from practical investigations related to three clock sites in Germany and one in France. The estimated uncertainty for the relativistic redshift correction at each site is about 2 × 10^{-18}.

Micropredation on sea urchins as a potential stabilizing process for rocky reefs

NASA Astrophysics Data System (ADS)

Bonaviri, Chiara; Gianguzza, Paola; Pipitone, Carlo; Hereu, Bernat

2012-10-01

Rocky reefs can shift from forest, a state dominated by erect algae with high biodiversity, to barren, an impoverished state dominated by encrusting algae. Sea urchins, abundant in barrens, are usually held responsible for the maintenance of this state. Predation by large fish can revert the barren state to forest by controlling sea urchin populations. However, the persistence of a community state sometimes seems to be independent from the presence of such large predators, suggesting the existence of other unknown mechanisms ensuring their stability. Theoretical studies suggest that the settler stage of sea urchins is determinant for maintaining a given rocky reef state. In this study, we have identified several potential invertebrate micropredators of settlers of the sea urchin Paracentrotus lividus and measured their predation activity. Predation rates showed marked differences among species, possibly due to morphological and/or behavioral traits. Micropredators were more abundant in the forest than in barren, and their potential impact on the sea urchin community differed between the two states by two orders of magnitude. These findings suggest a novel self-perpetuating mechanism stabilizing rocky reef systems, where the abundance of micropredators may contribute to shape the sea urchin population, which in turn is responsible for the persistence of the state.

Spatio-temporal population structuring and genetic diversity retention in depleted Atlantic Bluefin tuna of the Mediterranean Sea

PubMed Central

Riccioni, Giulia; Landi, Monica; Ferrara, Giorgia; Milano, Ilaria; Cariani, Alessia; Zane, Lorenzo; Sella, Massimo; Barbujani, Guido; Tinti, Fausto

2010-01-01

Fishery genetics have greatly changed our understanding of population dynamics and structuring in marine fish. In this study, we show that the Atlantic Bluefin tuna (ABFT, Thunnus thynnus), an oceanic predatory species exhibiting highly migratory behavior, large population size, and high potential for dispersal during early life stages, displays significant genetic differences over space and time, both at the fine and large scales of variation. We compared microsatellite variation of contemporary (n = 256) and historical (n = 99) biological samples of ABFTs of the central-western Mediterranean Sea, the latter dating back to the early 20th century. Measures of genetic differentiation and a general heterozygote deficit suggest that differences exist among population samples, both now and 96–80 years ago. Thus, ABFTs do not represent a single panmictic population in the Mediterranean Sea. Statistics designed to infer changes in population size, both from current and past genetic variation, suggest that some Mediterranean ABFT populations, although still not severely reduced in their genetic potential, might have suffered from demographic declines. The short-term estimates of effective population size are straddled on the minimum threshold (effective population size = 500) indicated to maintain genetic diversity and evolutionary potential across several generations in natural populations. PMID:20080643

A sex-specific trade-off between mating preferences for genetic compatibility and body size in a cichlid fish with mutual mate choice.

PubMed

Thünken, Timo; Meuthen, Denis; Bakker, Theo C M; Baldauf, Sebastian A

2012-08-07

Mating preferences for genetic compatibility strictly depend on the interplay of the genotypes of potential partners and are therein fundamentally different from directional preferences for ornamental secondary sexual traits. Thus, the most compatible partner is on average not the one with most pronounced ornaments and vice versa. Hence, mating preferences may often conflict. Here, we present a solution to this problem while investigating the interplay of mating preferences for relatedness (a compatibility criterion) and large body size (an ornamental or quality trait). In previous experiments, both sexes of Pelvicachromis taeniatus, a cichlid fish with mutual mate choice, showed preferences for kin and large partners when these criteria were tested separately. In the present study, test fish were given a conflicting choice between two potential mating partners differing in relatedness as well as in body size in such a way that preferences for both criteria could not simultaneously be satisfied. We show that a sex-specific trade-off occurs between mating preferences for body size and relatedness. For females, relatedness gained greater importance than body size, whereas the opposite was true for males. We discuss the potential role of the interplay between mating preferences for relatedness and body size for the evolution of inbreeding preference.

A sex-specific trade-off between mating preferences for genetic compatibility and body size in a cichlid fish with mutual mate choice

PubMed Central

Thünken, Timo; Meuthen, Denis; Bakker, Theo C. M.; Baldauf, Sebastian A.

2012-01-01

Mating preferences for genetic compatibility strictly depend on the interplay of the genotypes of potential partners and are therein fundamentally different from directional preferences for ornamental secondary sexual traits. Thus, the most compatible partner is on average not the one with most pronounced ornaments and vice versa. Hence, mating preferences may often conflict. Here, we present a solution to this problem while investigating the interplay of mating preferences for relatedness (a compatibility criterion) and large body size (an ornamental or quality trait). In previous experiments, both sexes of Pelvicachromis taeniatus, a cichlid fish with mutual mate choice, showed preferences for kin and large partners when these criteria were tested separately. In the present study, test fish were given a conflicting choice between two potential mating partners differing in relatedness as well as in body size in such a way that preferences for both criteria could not simultaneously be satisfied. We show that a sex-specific trade-off occurs between mating preferences for body size and relatedness. For females, relatedness gained greater importance than body size, whereas the opposite was true for males. We discuss the potential role of the interplay between mating preferences for relatedness and body size for the evolution of inbreeding preference. PMID:22513859

Effects of wildlife and cattle on tick abundance in central Kenya.

PubMed

Keesing, Felicia; Allan, Brian F; Young, Truman P; Ostfeld, Richard S

2013-09-01

In African savannas, large mammals, both wild and domestic, support an abundant and diverse population of tick ectoparasites. Because of the density of ticks and the many pathogens that they vector, cattle in East Africa are often treated with acaricides. While acaricides are known to be effective at reducing tick burdens on cattle, their effects on the overall abundance and community composition of ticks in savanna ecosystems are less well understood. It is also not known how well tick populations can be maintained in the absence of large mammals. We evaluated the effects of wildlife and of acaricide-treated cattle on host-seeking tick populations in a long-term, exclusion experiment in central Kenya. Over seven years, we sampled larval, nymphal, and adult ticks monthly on replicated treatment plots that controlled for the presence of cattle and for the presence of two guilds of large wild mammals: megaherbivores (giraffes and elephants) and all other large wild herbivores (> 15 kg). Two species of ticks were found in this habitat; across all surveys, 93% were Rhipicephalus pulchellus and 7% were R. praetextatus. The presence of acaricide-treated cattle dramatically reduced the abundance of host-seeking nymphal and adult ticks but did not affect the abundance of host-seeking larval ticks. The abundance of larval ticks was determined by the presence of large wild mammals, which appear to import gravid female ticks into the experimental plots. On plots with no large mammals, either wild or domestic, larval and nymphal ticks were rare. Adult R. pulchellus were most abundant in plots that allowed wildlife but excluded cattle. Adult R. praetextatus were relatively abundant in plots without any large mammals. These differences suggest that these ticks utilize different members of the host community. The reduction in ticks that results from the presence of acaricide-treated cattle has potential health benefits for humans and wildlife, but these benefits must be weighed against potential costs, including reduced availability of food for birds such as oxpeckers that feed on ticks.

Properties of slow oscillation during slow-wave sleep and anesthesia in cats

PubMed Central

Chauvette, Sylvain; Crochet, Sylvain; Volgushev, Maxim; Timofeev, Igor

2011-01-01

Deep anesthesia is commonly used as a model of slow-wave sleep (SWS). Ketamine-xylazine anesthesia reproduces the main features of sleep slow oscillation: slow, large amplitude waves in field potential, which are generated by the alternation of hyperpolarized and depolarized states of cortical neurons. However, direct quantitative comparison of field potential and membrane potential fluctuations during natural sleep and anesthesia is lacking, so it remains unclear how well the properties of sleep slow oscillation are reproduced by the ketamine-xylazine anesthesia model. Here, we used field potential and intracellular recordings in different cortical areas in the cat, to directly compare properties of slow oscillation during natural sleep and ketamine-xylazine anesthesia. During SWS cortical activity showed higher power in the slow/delta (0.1-4 Hz) and spindle (8-14 Hz) frequency range, while under anesthesia the power in the gamma band (30-100 Hz) was higher. During anesthesia, slow waves were more rhythmic and more synchronous across the cortex. Intracellular recordings revealed that silent states were longer and the amplitude of membrane potential around transition between active and silent states was bigger under anesthesia. Slow waves were largely uniform across cortical areas under anesthesia, but in SWS they were most pronounced in associative and visual areas, but smaller and less regular in somatosensory and motor cortices. We conclude that although the main features of the slow oscillation in sleep and anesthesia appear similar, multiple cellular and network features are differently expressed during natural SWS as compared to ketamine-xylazine anesthesia. PMID:22016533

Contribution potential of glaciers to water availability in different climate regimes

PubMed Central

Kaser, Georg; Großhauser, Martin; Marzeion, Ben

2010-01-01

Although reliable figures are often missing, considerable detrimental changes due to shrinking glaciers are universally expected for water availability in river systems under the influence of ongoing global climate change. We estimate the contribution potential of seasonally delayed glacier melt water to total water availability in large river systems. We find that the seasonally delayed glacier contribution is largest where rivers enter seasonally arid regions and negligible in the lowlands of river basins governed by monsoon climates. By comparing monthly glacier melt contributions with population densities in different altitude bands within each river basin, we demonstrate that strong human dependence on glacier melt is not collocated with highest population densities in most basins. PMID:21059938

Comparison of event related potentials with and without hypnagogic imagery.

PubMed

Michida, N; Hayashi, M; Hori, T

1998-04-01

It is hypothesized that when hypnagogic imagery occurs, an appropriate attention may allocate to the imagery, resulting in the allocation of attention to the external tone stimuli being diminished. N3 amplitude of event related potentials (ERP) obtained a significant difference between the conditions with and without imagery. Arousal level of behavior and electroencephalography were not different between the conditions, therefore it is interpreted that the decrease of the N3 amplitude during imagining reflects the diminution of the allocation of attention to the external tone stimuli. Another late component of ERP, P3, did not make clear peaks in this study despite a large time constant (tau=3.2 s) used for EEG records.

Measurement and modeling of polarized specular neutron reflectivity in large magnetic fields.

PubMed

Maranville, Brian B; Kirby, Brian J; Grutter, Alexander J; Kienzle, Paul A; Majkrzak, Charles F; Liu, Yaohua; Dennis, Cindi L

2016-08-01

The presence of a large applied magnetic field removes the degeneracy of the vacuum energy states for spin-up and spin-down neutrons. For polarized neutron reflectometry, this must be included in the reference potential energy of the Schrödinger equation that is used to calculate the expected scattering from a magnetic layered structure. For samples with magnetization that is purely parallel or antiparallel to the applied field which defines the quantization axis, there is no mixing of the spin states (no spin-flip scattering) and so this additional potential is constant throughout the scattering region. When there is non-collinear magnetization in the sample, however, there will be significant scattering from one spin state into the other, and the reference potentials will differ between the incoming and outgoing wavefunctions, changing the angle and intensities of the scattering. The theory of the scattering and recommended experimental practices for this type of measurement are presented, as well as an example measurement.

Measurement and modeling of polarized specular neutron reflectivity in large magnetic fields

PubMed Central

Maranville, Brian B.; Kirby, Brian J.; Grutter, Alexander J.; Kienzle, Paul A.; Majkrzak, Charles F.; Liu, Yaohua; Dennis, Cindi L.

2016-01-01

The presence of a large applied magnetic field removes the degeneracy of the vacuum energy states for spin-up and spin-down neutrons. For polarized neutron reflectometry, this must be included in the reference potential energy of the Schrödinger equation that is used to calculate the expected scattering from a magnetic layered structure. For samples with magnetization that is purely parallel or antiparallel to the applied field which defines the quantization axis, there is no mixing of the spin states (no spin-flip scattering) and so this additional potential is constant throughout the scattering region. When there is non-collinear magnetization in the sample, however, there will be significant scattering from one spin state into the other, and the reference potentials will differ between the incoming and outgoing wavefunctions, changing the angle and intensities of the scattering. The theory of the scattering and recommended experimental practices for this type of measurement are presented, as well as an example measurement. PMID:27504074

Measurement and modeling of polarized specular neutron reflectivity in large magnetic fields

DOE PAGES

Maranville, Brian B.; Kirby, Brian J.; Grutter, Alexander J.; ...

2016-06-09

The presence of a large applied magnetic field removes the degeneracy of the vacuum energy states for spin-up and spin-down neutrons. For polarized neutron reflectometry, this must be included in the reference potential energy of the Schrödinger equation that is used to calculate the expected scattering from a magnetic layered structure. For samples with magnetization that is purely parallel or antiparallel to the applied field which defines the quantization axis, there is no mixing of the spin states (no spin-flip scattering) and so this additional potential is constant throughout the scattering region. When there is non-collinear magnetization in the sample,more » however, there will be significant scattering from one spin state into the other, and the reference potentials will differ between the incoming and outgoing wavefunctions, changing the angle and intensities of the scattering. In conclusion, the theory of the scattering and recommended experimental practices for this type of measurement are presented, as well as an example measurement.« less

Role of data warehousing in healthcare epidemiology.

PubMed

Wyllie, D; Davies, J

2015-04-01

Electronic storage of healthcare data, including individual-level risk factors for both infectious and other diseases, is increasing. These data can be integrated at hospital, regional and national levels. Data sources that contain risk factor and outcome information for a wide range of conditions offer the potential for efficient epidemiological analysis of multiple diseases. Opportunities may also arise for monitoring healthcare processes. Integrating diverse data sources presents epidemiological, practical, and ethical challenges. For example, diagnostic criteria, outcome definitions, and ascertainment methods may differ across the data sources. Data volumes may be very large, requiring sophisticated computing technology. Given the large populations involved, perhaps the most challenging aspect is how informed consent can be obtained for the development of integrated databases, particularly when it is not easy to demonstrate their potential. In this article, we discuss some of the ups and downs of recent projects as well as the potential of data warehousing for antimicrobial resistance monitoring. Copyright © 2015. Published by Elsevier Ltd.

Mosquito species composition and phenology (Diptera, Culicidae) in two German zoological gardens imply different risks of mosquito-borne pathogen transmission.

PubMed

Heym, Eva C; Kampen, Helge; Walther, Doreen

2018-06-01

Due to their large diversity of potential blood hosts, breeding habitats, and resting sites, zoological gardens represent highly interesting places to study mosquito ecology. In order to better assess the risk of mosquito-borne disease-agent transmission in zoos, potential vector species must be known, as well as the communities in which they occur. For this reason, species composition and dynamics were examined in 2016 in two zoological gardens in Germany. Using different methods for mosquito sampling, a total of 2,257 specimens belonging to 20 taxa were collected. Species spectra depended on the collection method but generally differed between the two zoos, while species compositions and relative abundances varied seasonally in both of them. As both sampled zoos were located in the same climatic region and potential breeding sites within the zoos were similar, the differences in mosquito compositions are attributed to immigration of specimens from surrounding landscapes, although the different sizes of the zoos and the different blood host populations available probably also have an impact. Based on the differences in species composition and the various biological characteristics of the species, the risk of certain pathogens to be transmitted must also be expected to differ between the zoos. © 2018 The Society for Vector Ecology.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watkins, W.T.; Siebers, J.V.; Bzdusek, K.

Purpose: To introduce methods to analyze Deformable Image Registration (DIR) and identify regions of potential DIR errors. Methods: DIR Deformable Vector Fields (DVFs) quantifying patient anatomic changes were evaluated using the Jacobian determinant and the magnitude of DVF curl as functions of tissue density and tissue type. These quantities represent local relative deformation and rotation, respectively. Large values in dense tissues can potentially identify non-physical DVF errors. For multiple DVFs per patient, histograms and visualization of DVF differences were also considered. To demonstrate the capabilities of methods, we computed multiple DVFs for each of five Head and Neck (H'N) patientsmore » (P1–P5) via a Fast-symmetric Demons (FSD) algorithm and via a Diffeomorphic Demons (DFD) algorithm, and show the potential to identify DVF errors. Results: Quantitative comparisons of the FSD and DFD registrations revealed <0.3 cm DVF differences in >99% of all voxels for P1, >96% for P2, and >90% of voxels for P3. While the FSD and DFD registrations were very similar for these patients, the Jacobian determinant was >50% in 9–15% of soft tissue and in 3–17% of bony tissue in each of these cases. The volumes of large soft tissue deformation were consistent for all five patients using the FSD algorithm (mean 15%±4% volume), whereas DFD reduced regions of large deformation by 10% volume (785 cm{sup 3}) for P4 and by 14% volume (1775 cm{sup 3}) for P5. The DFD registrations resulted in fewer regions of large DVF-curl; 50% rotations in FSD registrations averaged 209±136 cm{sup 3} in soft tissue and 10±11 cm{sup 3} in bony tissue, but using DFD these values were reduced to 42±53 cm{sup 3} and 1.1±1.5 cm{sup 3}, respectively. Conclusion: Analysis of Jacobian determinant and curl as functions of tissue density can identify regions of potential DVF errors by identifying non-physical deformations and rotations. Collaboration with Phillips Healthcare, as indicated in authorship.« less

Prototypic Development and Evaluation of a Medium Format Metric Camera

NASA Astrophysics Data System (ADS)

Hastedt, H.; Rofallski, R.; Luhmann, T.; Rosenbauer, R.; Ochsner, D.; Rieke-Zapp, D.

2018-05-01

Engineering applications require high-precision 3D measurement techniques for object sizes that vary between small volumes (2-3 m in each direction) and large volumes (around 20 x 20 x 1-10 m). The requested precision in object space (1σ RMS) is defined to be within 0.1-0.2 mm for large volumes and less than 0.01 mm for small volumes. In particular, focussing large volume applications the availability of a metric camera would have different advantages for several reasons: 1) high-quality optical components and stabilisations allow for a stable interior geometry of the camera itself, 2) a stable geometry leads to a stable interior orientation that enables for an a priori camera calibration, 3) a higher resulting precision can be expected. With this article the development and accuracy evaluation of a new metric camera, the ALPA 12 FPS add|metric will be presented. Its general accuracy potential is tested against calibrated lengths in a small volume test environment based on the German Guideline VDI/VDE 2634.1 (2002). Maximum length measurement errors of less than 0.025 mm are achieved with different scenarios having been tested. The accuracy potential for large volumes is estimated within a feasibility study on the application of photogrammetric measurements for the deformation estimation on a large wooden shipwreck in the German Maritime Museum. An accuracy of 0.2 mm-0.4 mm is reached for a length of 28 m (given by a distance from a lasertracker network measurement). All analyses have proven high stabilities of the interior orientation of the camera and indicate the applicability for a priori camera calibration for subsequent 3D measurements.

Is a New Urban Development Model Building Greener Communities?

ERIC Educational Resources Information Center

Youngentob, Kara; Hostetler, Mark

2005-01-01

Although neotraditional architecture largely focuses on promoting sense of community (SOC), it has the potential to influence environmentalism in residents as well. In October 2002, the authors conducted a mail survey of 1,611 middleclass homeowners in Gainesville, Florida, to determine if there were differences in SOC and environmental behaviors,…

Hydrodynamic Versus Size-Exclusion Chromatography Characterization of Alternan and Comparison to Off-Line MALS

USDA-ARS?s Scientific Manuscript database

Alternan is an ultra-high molar mass polysaccharide composed of two different types of glycosidic linkages and which also possesses long-chain branching. It has great potential in a number of areas, including as a possible domestic replacement for gum Arabic. The high molar mass and large size of ...

Perturbation corrections to Koopmans' theorem. V - A study with large basis sets

NASA Technical Reports Server (NTRS)

Chong, D. P.; Langhoff, S. R.

1982-01-01

The vertical ionization potentials of N2, F2 and H2O were calculated by perturbation corrections to Koopmans' theorem using six different basis sets. The largest set used includes several sets of polarization functions. Comparison is made with measured values and with results of computations using Green's functions.

Feed-forward and generalized regression neural networks in modeling feeding behavior of pigs in the grow-finishing phase

USDA-ARS?s Scientific Manuscript database

Feeding patterns in group-housed grow-finishing pigs have been investigated for use in management decisions, identifying sick animals, and determining genetic differences within a herd. Development of models to predict swine feeding behaviour has been limited due the large number of potential enviro...

Direct and rapid determination of cotton maturity by FT-Mid-IR technique

USDA-ARS?s Scientific Manuscript database

FT-mid-IR (FT-MIR) spectra of seed and lint cottons were collected to explore the potential for the discrimination of immature cottons from mature ones and also for the determination of actual cotton maturity. Spectral features of immature and mature cottons revealed large differences in the 1200-90...

General proactive interference and the N450 response.

PubMed

Tays, William J; Dywan, Jane; Segalowitz, Sidney J

2009-10-25

Strategic repetition of verbal stimuli can effectively produce proactive interference (PI) effects in the Sternberg working memory task. Unique fronto-cortical activation to PI-eliciting letter probes has been interpreted as reflecting brain responses to PI. However, the use of only a small set of stimuli (e.g., letters and digits) requires constant repetition of stimuli in both PI and baseline trials, potentially creating a general PI effect in all conditions. We used event-related potentials to examine general PI effects by contrasting the interference-related frontal N450 response in two Sternberg tasks using a small versus large set size. We found that the N450 response differed significantly from baseline during the small set-size task only for response-conflict PI trials but not when PI was created solely from stimulus repetition. During the large set-size task N450 responses in both the familiarity-based and response-conflict PI conditions differed from baseline but not from each other. We conclude that the general stimulus repetition inherent in small set-size conditions can mask effects of familiarity-based PI and complicate the interpretation of any associated neural response.

The Methodology Applied in DPPH, ABTS and Folin-Ciocalteau Assays Has a Large Influence on the Determined Antioxidant Potential.

PubMed

Abramovič, Helena; Grobin, Blaž; Poklar, Nataša; Cigić, Blaž

2017-06-01

Antioxidant potential (AOP) is not only the property of the matrix analyzed but also depends greatly on the methodology used. The chromogenic radicals 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and Folin-Ciocalteu (FC) assay were applied to estimate how the method and the composition of the assay solvent influence the AOP determined for coffee, tea, beer, apple juice and dietary supplements. Large differences between the AOP values depending on the reaction medium were observed, with the highest AOP determined mostly in the FC assay. In reactions with chromogenic radicals several fold higher values of AOP were obtained in buffer pH 7.4 than in water or methanol. The type of assay and solvent composition have similar influences on the reactivity of a particular antioxidant, either pure or as part of a complex matrix. The reaction kinetics of radicals with antioxidants in samples reveals that AOP depends strongly on incubation time, yet differently for each sample analyzed and the assay applied.

Graphene decorated microelectrodes for simultaneous detection of ascorbic, dopamine, and folic acids by means of chemical vapor deposition

NASA Astrophysics Data System (ADS)

Namdar, N.; Hassanpour Amiri, M.; Dehghan Nayeri, F.; Gholizadeh, A.; Mohajerzadeh, S.

2015-09-01

In this paper, high quality and large area graphene layers were synthesized using thermal chemical vapour deposition on copper foil substrates. We use graphene incorporated electrodes to measure simultaneously ascorbic acid, dopamine and folic acid. Cyclic voltammetry and differential pulse voltammetry methods were used to evaluate electrochemical behaviour of the grown graphene layers. The graphene-modified electrode shows large electrochemical potential difference compared to bare gold electrodes with higher current responses. Also our fabricated electrodes configuration can be used easily for microfluidic analysis.

Cumulative effect of zinc oxide and titanium oxide nanoparticles on growth and chlorophyll a content of Picochlorum sp.

PubMed

Hazeem, Layla J; Bououdina, Mohammed; Rashdan, Suad; Brunet, Loïc; Slomianny, Christian; Boukherroub, Rabah

2016-02-01

The use of nanoparticles (NPs) is of increasing significance due to their large potential for various applications. Great attention should be paid on the possible impacts of nanoparticles on the environment as large amounts of them may reach the environment by accident or voluntarily. Marine algae are potential organisms for usage in nanopollution bioremediation in aquatic system, because of their ability to adapt to long exposure to NPs. Thus, it is of prime importance to study the possible interactions of different NPs with microalgae in assessing their potential environmental risks. Most studies on potential environmental effects of ZnO and TiO2 NPs have been performed independently and following the widely accepted, standardized test systems, which had been developed for the characterization of chemicals. In this study, we have examined the cumulative effect of ZnO and TiO2 NPs on Picochlorum sp. in addition to the individual effects of these NPs over 32 days. Our results indicate that the toxicity and availability of NPs to marine algae are reduced by their aggregation and sedimentation. NPs are found to have a negative effect on algal growth and chlorophyll a concentration during the early growth stages. In contrast, the case is reversed during the late growth stages. There is no significant difference between the effect of the NPs when they are used separately and when both ZnO and TiO2 are used together in the test (P > 0.05).

Biomimetic Beetle-Inspired Flapping Air Vehicle Actuated by Ionic Polymer-Metal Composite Actuator.

PubMed

Zhao, Yang; Xu, Di; Sheng, Jiazheng; Meng, Qinglong; Wu, Dezhi; Wang, Lingyun; Xiao, Jingjing; Lv, Wenlong; Chen, Qinnan; Sun, Daoheng

2018-01-01

During the last decades, the ionic polymer-metal composite (IPMC) received much attention because of its potential capabilities, such as large displacement and flexible bending actuation. In this paper, a biomimetic flapping air vehicle was proposed by combining the superiority of ionic polymer metal composite with the bionic beetle flapping principle. The blocking force was compared between casted IPMC and IPMC. The flapping state of the wing was investigated and the maximum displacement and flapping angle were measured. The flapping displacement under different voltage and frequency was tested. The flapping displacement of the wing and the support reaction force were measured under different frequency by experiments. The experimental results indicate that the high voltage and low frequency would get large flapping displacement.

Recent NASA Research on Aerodynamic Modeling of Post-Stall and Spin Dynamics of Large Transport Airplanes

NASA Technical Reports Server (NTRS)

Murch, Austin M.; Foster, John V.

2007-01-01

A simulation study was conducted to investigate aerodynamic modeling methods for prediction of post-stall flight dynamics of large transport airplanes. The research approach involved integrating dynamic wind tunnel data from rotary balance and forced oscillation testing with static wind tunnel data to predict aerodynamic forces and moments during highly dynamic departure and spin motions. Several state-of-the-art aerodynamic modeling methods were evaluated and predicted flight dynamics using these various approaches were compared. Results showed the different modeling methods had varying effects on the predicted flight dynamics and the differences were most significant during uncoordinated maneuvers. Preliminary wind tunnel validation data indicated the potential of the various methods for predicting steady spin motions.

Inter-layer potential for hexagonal boron nitride

NASA Astrophysics Data System (ADS)

Leven, Itai; Azuri, Ido; Kronik, Leeor; Hod, Oded

2014-03-01

A new interlayer force-field for layered hexagonal boron nitride (h-BN) based structures is presented. The force-field contains three terms representing the interlayer attraction due to dispersive interactions, repulsion due to anisotropic overlaps of electron clouds, and monopolar electrostatic interactions. With appropriate parameterization, the potential is able to simultaneously capture well the binding and lateral sliding energies of planar h-BN based dimer systems as well as the interlayer telescoping and rotation of double walled boron-nitride nanotubes of different crystallographic orientations. The new potential thus allows for the accurate and efficient modeling and simulation of large-scale h-BN based layered structures.

Adsorbed molecules in external fields: Effect of confining potential.

PubMed

Tyagi, Ashish; Silotia, Poonam; Maan, Anjali; Prasad, Vinod

2016-12-05

We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials. Copyright © 2016 Elsevier B.V. All rights reserved.

Discharge characteristics of biceps brachii motor units at recruitment when older adults sustained an isometric contraction.

PubMed

Pascoe, Michael A; Holmes, Matthew R; Enoka, Roger M

2011-02-01

The purpose of this study was to compare the discharge characteristics of motor units recruited during an isometric contraction that was sustained with the elbow flexor muscles by older adults at target forces that were less than the recruitment threshold force of each isolated motor unit. The discharge times of 27 single motor units were recorded from the biceps brachii in 11 old adults (78.8 ± 5.9 yr). The target force was set at either a relatively small (6.6 ± 3.7% maximum) or large (11.4 ± 4.5% maximum) difference below the recruitment threshold force and the contraction was sustained until the motor unit was recruited and discharged action potentials for about 60 s. The time to recruitment was longer for the large target-force difference (P = 0.001). At recruitment, the motor units discharged repetitively for both target-force differences, which contrasts with data from young adults when motor units discharged intermittently at recruitment for the large difference between recruitment threshold force and target force. The coefficient of variation (CV) for the first five interspike intervals (ISIs) increased from the small (18.7 ± 7.9) to large difference (35.0 ± 10.2%, P = 0.008) for the young adults, but did not differ for the two target force differences for the old adults (26.3 ± 14.7 to 24.0 ± 13.1%, P = 0.610). When analyzed across the discharge duration, the average CV for the ISI decreased similarly for the two target-force differences (P = 0.618) in old adults. These findings contrast with those of young adults and indicate that the integration of synaptic input during sustained contractions differs between young and old adults.

Large-Scale Brain Systems in ADHD: Beyond the Prefrontal-Striatal Model

PubMed Central

Castellanos, F. Xavier; Proal, Erika

2012-01-01

Attention-deficit/hyperactivity disorder (ADHD) has long been thought to reflect dysfunction of prefrontal-striatal circuitry, with involvement of other circuits largely ignored. Recent advances in systems neuroscience-based approaches to brain dysfunction enable the development of models of ADHD pathophysiology that encompass a number of different large-scale “resting state” networks. Here we review progress in delineating large-scale neural systems and illustrate their relevance to ADHD. We relate frontoparietal, dorsal attentional, motor, visual, and default networks to the ADHD functional and structural literature. Insights emerging from mapping intrinsic brain connectivity networks provide a potentially mechanistic framework for understanding aspects of ADHD, such as neuropsychological and behavioral inconsistency, and the possible role of primary visual cortex in attentional dysfunction in the disorder. PMID:22169776

Robustness of inflation to inhomogeneous initial conditions

NASA Astrophysics Data System (ADS)

Clough, Katy; Lim, Eugene A.; DiNunno, Brandon S.; Fischler, Willy; Flauger, Raphael; Paban, Sonia

2017-09-01

We consider the effects of inhomogeneous initial conditions in both the scalar field profile and the extrinsic curvature on different inflationary models. In particular, we compare the robustness of small field inflation to that of large field inflation, using numerical simulations with Einstein gravity in 3+1 dimensions. We find that small field inflation can fail in the presence of subdominant gradient energies, suggesting that it is much less robust to inhomogeneities than large field inflation, which withstands dominant gradient energies. However, we also show that small field inflation can be successful even if some regions of spacetime start out in the region of the potential that does not support inflation. In the large field case, we confirm previous results that inflation is robust if the inflaton occupies the inflationary part of the potential. Furthermore, we show that increasing initial scalar gradients will not form sufficiently massive inflation-ending black holes if the initial hypersurface is approximately flat. Finally, we consider the large field case with a varying extrinsic curvature K, such that some regions are initially collapsing. We find that this may again lead to local black holes, but overall the spacetime remains inflationary if the spacetime is open, which confirms previous theoretical studies.

Large magnetic entropy change in multiferroic HoFeO3 single crystal

NASA Astrophysics Data System (ADS)

Das, Moumita; Mandal, Prabhat

2018-04-01

In this article magnetic and magnetocaloric properties of HoFeO3 single crystal have been investigated by magnetization measurement in the temperature range 6-30K and near spin reorientation transition (TSR) region 45-61K. Remarkably large and reversible magnetic entropy change (-ΔSm) = 27J/kg K, has been observed for a field change of 0-6T near 9.5K due to metamagnetic transition. The value of ΔSm is 6J/kg K at 6T near TSR. This magnetocaloric parameter is larger than previously reported value along [100] crystallographic axis due to its anisotropic nature along different axis. This value is larger than some of the potential magnetic refrigerants in the same temperature range which is not reported previously. The ΔSm is also quite large for a small and moderate field change. For an example the values of ΔSmax are 7 and 12 J/kg K for field change of 2 and 3T. The large value of this magnetocaloric parameter suggests that HoFeO3 could be considered as a potential refrigerant material for low-temperature magnetic refrigeration technology to liquefaction the hydrogen and helium in fuel industry.

Investigating potential transferability of place-based research in land system science

NASA Astrophysics Data System (ADS)

Václavík, Tomáš; Langerwisch, Fanny; Cotter, Marc; Fick, Johanna; Häuser, Inga; Hotes, Stefan; Kamp, Johannes; Settele, Josef; Spangenberg, Joachim H.; Seppelt, Ralf

2016-09-01

Much of our knowledge about land use and ecosystem services in interrelated social-ecological systems is derived from place-based research. While local and regional case studies provide valuable insights, it is often unclear how relevant this research is beyond the study areas. Drawing generalized conclusions about practical solutions to land management from local observations and formulating hypotheses applicable to other places in the world requires that we identify patterns of land systems that are similar to those represented by the case study. Here, we utilize the previously developed concept of land system archetypes to investigate potential transferability of research from twelve regional projects implemented in a large joint research framework that focus on issues of sustainable land management across four continents. For each project, we characterize its project archetype, i.e. the unique land system based on a synthesis of more than 30 datasets of land-use intensity, environmental conditions and socioeconomic indicators. We estimate the transferability potential of project research by calculating the statistical similarity of locations across the world to the project archetype, assuming higher transferability potentials in locations with similar land system characteristics. Results show that areas with high transferability potentials are typically clustered around project sites but for some case studies can be found in regions that are geographically distant, especially when values of considered variables are close to the global mean or where the project archetype is driven by large-scale environmental or socioeconomic conditions. Using specific examples from the local case studies, we highlight the merit of our approach and discuss the differences between local realities and information captured in global datasets. The proposed method provides a blueprint for large research programs to assess potential transferability of place-based studies to other geographical areas and to indicate possible gaps in research efforts.

Sex differences in mouse Transient Receptor Potential Cation Channel, Subfamily M, Member 8 expressing trigeminal ganglion neurons

PubMed Central

Caudle, Stephanie L.; Jenkins, Alan C.; Ahn, Andrew H.; Neubert, John K.

2017-01-01

The detection of cool temperatures is thought to be mediated by primary afferent neurons that express the cool temperature sensing protein Transient Receptor Potential Cation Channel, Subfamily M, Member 8 (TRPM8). Using mice, this study tested the hypothesis that sex differences in sensitivity to cool temperatures were mediated by differences in neurons that express TRPM8. Ion currents from TRPM8 expressing trigeminal ganglion (TRG) neurons in females demonstrated larger hyperpolarization-activated cyclic nucleotide-gated currents (Ih) than male neurons at both 30° and 18°C. Additionally, female neurons’ voltage gated potassium currents (Ik) were suppressed by cooling, whereas male Ik was not significantly affected. At the holding potential tested (-60mV) TRPM8 currents were not visibly activated in either sex by cooling. Modeling the effect of Ih and Ik on membrane potentials demonstrated that at 30° the membrane potential in both sexes is unstable. At 18°, female TRPM8 TRG neurons develop a large oscillating pattern in their membrane potential, whereas male neurons become highly stable. These findings suggest that the differences in Ih and Ik in the TRPM8 TRG neurons of male and female mice likely leads to greater sensitivity of female mice to the cool temperature. This hypothesis was confirmed in an operant reward/conflict assay. Female mice contacted an 18°C surface for approximately half the time that males contacted the cool surface. At 33° and 10°C male and female mice contacted the stimulus for similar amounts of time. These data suggest that sex differences in the functioning of Ih and Ik in TRPM8 expressing primary afferent neurons leads to differences in cool temperature sensitivity. PMID:28472061

Application of a design-build-team approach to low cost and weight composite fuselage structure

NASA Technical Reports Server (NTRS)

Ilcewicz, L. B.; Walker, T. H.; Willden, K. S.; Swanson, G. D.; Truslove, G.; Metschan, S. L.; Pfahl, C. L.

1991-01-01

Relationships between manufacturing costs and design details must be understood to promote the application of advanced composite technologies to transport fuselage structures. A team approach, integrating the disciplines responsible for aircraft structural design and manufacturing, was developed to perform cost and weight trade studies for a twenty-foot diameter aft fuselage section. Baseline composite design and manufacturing concepts were selected for large quadrant panels in crown, side, and keel areas of the fuselage section. The associated technical issues were also identified. Detailed evaluation of crown panels indicated the potential for large weight savings and costs competitive with aluminum technology in the 1995 timeframe. Different processes and material forms were selected for the various elements that comprise the fuselage structure. Additional cost and weight savings potential was estimated for future advancements.

The limits of weak selection and large population size in evolutionary game theory.

PubMed

Sample, Christine; Allen, Benjamin

2017-11-01

Evolutionary game theory is a mathematical approach to studying how social behaviors evolve. In many recent works, evolutionary competition between strategies is modeled as a stochastic process in a finite population. In this context, two limits are both mathematically convenient and biologically relevant: weak selection and large population size. These limits can be combined in different ways, leading to potentially different results. We consider two orderings: the [Formula: see text] limit, in which weak selection is applied before the large population limit, and the [Formula: see text] limit, in which the order is reversed. Formal mathematical definitions of the [Formula: see text] and [Formula: see text] limits are provided. Applying these definitions to the Moran process of evolutionary game theory, we obtain asymptotic expressions for fixation probability and conditions for success in these limits. We find that the asymptotic expressions for fixation probability, and the conditions for a strategy to be favored over a neutral mutation, are different in the [Formula: see text] and [Formula: see text] limits. However, the ordering of limits does not affect the conditions for one strategy to be favored over another.

A prototype splitter apparatus for dividing large catches of small fish

USGS Publications Warehouse

Stapanian, Martin A.; Edwards, William H.

2012-01-01

Due to financial and time constraints, it is often necessary in fisheries studies to divide large samples of fish and estimate total catch from the subsample. The subsampling procedure may involve potential human biases or may be difficult to perform in rough conditions. We present a prototype gravity-fed splitter apparatus for dividing large samples of small fish (30–100 mm TL). The apparatus features a tapered hopper with a sliding and removable shutter. The apparatus provides a comparatively stable platform for objectively obtaining subsamples, and it can be modified to accommodate different sizes of fish and different sample volumes. The apparatus is easy to build, inexpensive, and convenient to use in the field. To illustrate the performance of the apparatus, we divided three samples (total N = 2,000 fish) composed of four fish species. Our results indicated no significant bias in estimating either the number or proportion of each species from the subsample. Use of this apparatus or a similar apparatus can help to standardize subsampling procedures in large surveys of fish. The apparatus could be used for other applications that require dividing a large amount of material into one or more smaller subsamples.

Revealing infinite derivative gravity's true potential: The weak-field limit around de Sitter backgrounds

NASA Astrophysics Data System (ADS)

Edholm, James

2018-03-01

General Relativity is known to produce singularities in the potential generated by a point source. Our universe can be modeled as a de Sitter (dS) metric and we show that ghost-free infinite derivative gravity (IDG) produces a nonsingular potential around a dS background, while returning to the GR prediction at large distances. We also show that although there are an apparently infinite number of coefficients in the theory, only a finite number actually affect the predictions. By writing the linearized equations of motion in a simplified form, we find that at distances below the Hubble length scale, the difference between the IDG potential around a flat background and around a de Sitter background is negligible.

Investigation of Hydrological Response of Three Identical Artificial Hillslopes at the Landscape Evolution Observatory

NASA Astrophysics Data System (ADS)

Matos, K.; Alves Meira Neto, A.; Troch, P. A. A.; Volkmann, T.

2017-12-01

Hydrological processes at the hillslope scale are complex and heterogeneous, but monitoring hillslopes with a large number of sensors or replicate experimental designs is rarely feasible. The Landscape Evolution Observatory (LEO) at Biosphere 2 consists of three replicated, large (330 m2) artificial hillslopes (East, Center and West) packed with 1-m depth of initially homogeneous, basaltic soil. Each landscape contains a spatially dense network of sensors capable of resolving meter-scale lateral heterogeneity and sub-meter scale vertical heterogeneity in moisture content and water potential, as well as the hillslope-integrated water balance components. A sophisticated irrigation system allows performing controlled forcing experiments. The three hillslopes are thought to be nearly identical, however recent data showed significant differences in discharge and storage behavior. A 45-day periodic-steady-state tracer experiment was conducted in November and December of 2016, where a 3.5-day long, identical irrigation sequence was repeated 15 times. Each sequence's rainfall, runoff, and storage dynamics were recorded, and distributed moisture characteristics were derived using paired moisture content and matric potential data from 496 positions in each hillslope. In order to understand why the three hillslopes behave hydrologically different, we analyzed soil water retention characteristics at various scales ranging from individually paired moisture and matric potential to whole-hillslope soil water retention characteristics. The results confirm the distinct hydrological behavior between the three hillslopes. The East and West hillslopes behave more similar with respect to the release of water. In contrast, the East and Center hillslopes are more similar with respect to their storage behavior. The differences in hillslope behavior arising from three identically built hillslopes are a surprising and beneficial opportunity to explore how differences in small-scale heterogeneity can impact hydrological dynamics at the hillslope scale.

Fractionation of Hydrogen Isotopes by Sulfate- and Nitrate-Reducing Bacteria.

PubMed

Osburn, Magdalena R; Dawson, Katherine S; Fogel, Marilyn L; Sessions, Alex L

2016-01-01

Hydrogen atoms from water and food are incorporated into biomass during cellular metabolism and biosynthesis, fractionating the isotopes of hydrogen-protium and deuterium-that are recorded in biomolecules. While these fractionations are often relatively constant in plants, large variations in the magnitude of fractionation are observed for many heterotrophic microbes utilizing different central metabolic pathways. The correlation between metabolism and lipid δ(2)H provides a potential basis for reconstructing environmental and ecological parameters, but the calibration dataset has thus far been limited mainly to aerobes. Here we report on the hydrogen isotopic fractionations of lipids produced by nitrate-respiring and sulfate-reducing bacteria. We observe only small differences in fractionation between oxygen- and nitrate-respiring growth conditions, with a typical pattern of variation between substrates that is broadly consistent with previously described trends. In contrast, fractionation by sulfate-reducing bacteria does not vary significantly between different substrates, even when autotrophic and heterotrophic growth conditions are compared. This result is in marked contrast to previously published observations and has significant implications for the interpretation of environmental hydrogen isotope data. We evaluate these trends in light of metabolic gene content of each strain, growth rate, and potential flux and reservoir-size effects of cellular hydrogen, but find no single variable that can account for the differences between nitrate- and sulfate-respiring bacteria. The emerging picture of bacterial hydrogen isotope fractionation is therefore more complex than the simple correspondence between δ(2)H and metabolic pathway previously understood from aerobes. Despite the complexity, the large signals and rich variability of observed lipid δ(2)H suggest much potential as an environmental recorder of metabolism.

Meaning of the field dependence of the renormalization scale in Higgs inflation

NASA Astrophysics Data System (ADS)

Hamada, Yuta; Kawai, Hikaru; Nakanishi, Yukari; Oda, Kin-ya

2017-05-01

We consider the prescription dependence of the Higgs effective potential under the presence of general nonminimal couplings. We evaluate the fermion loop correction to the effective action in a simplified Higgs-Yukawa model whose path integral measure takes simple form either in the Jordan or Einstein frame. The resultant effective action becomes identical in both cases when we properly take into account the quartically divergent term coming from the change of measure. Working in the counterterm formalism, we clarify that the difference between the prescriptions I and II comes from the counter term to cancel the logarithmic divergence. This difference can be absorbed into the choice of tree-level potential from the infinitely many possibilities, including all the higher-dimensional terms. We also present another mechanism to obtain a flat potential by freezing the running of the effective quartic coupling for large field values, using the nonminimal coupling in the gauge kinetic function.

Statistical Primer on Biosimilar Clinical Development.

PubMed

Isakov, Leah; Jin, Bo; Jacobs, Ira Allen

A biosimilar is highly similar to a licensed biological product and has no clinically meaningful differences between the biological product and the reference (originator) product in terms of safety, purity, and potency and is approved under specific regulatory approval processes. Because both the originator and the potential biosimilar are large and structurally complex proteins, biosimilars are not generic equivalents of the originator. Thus, the regulatory approach for a small-molecule generic is not appropriate for a potential biosimilar. As a result, different study designs and statistical approaches are used in the assessment of a potential biosimilar. This review covers concepts and terminology used in statistical analyses in the clinical development of biosimilars so that clinicians can understand how similarity is evaluated. This should allow the clinician to understand the statistical considerations in biosimilar clinical trials and make informed prescribing decisions when an approved biosimilar is available.

Limits of the potential flow approach to the single-mode Rayleigh-Taylor problem

NASA Astrophysics Data System (ADS)

Ramaprabhu, P.; Dimonte, Guy; Young, Yuan-Nan; Calder, A. C.; Fryxell, B.

2006-12-01

We report on the behavior of a single-wavelength Rayleigh-Taylor flow at late times. The calculations were performed in a long square duct (λ×λ×8λ) , using four different numerical simulations. In contradiction with potential flow theories that predict a constant terminal velocity, the single-wavelength Rayleigh-Taylor problem exhibits late-time acceleration. The onset of acceleration occurs as the bubble penetration depth exceeds the diameter of bubbles, and is observed for low and moderate density differences. Based on our simulations, we provide a phenomenological description of the observed acceleration, and ascribe this behavior to the formation of Kelvin-Helmholtz vortices on the bubble-spike interface that diminish the friction drag, while the associated induced flow propels the bubbles forward. For large density ratios, the formation of secondary instabilities is suppressed, and the bubbles remain terminal consistent with potential flow models.

Implementation Issues for Departure Planning Systems

NASA Technical Reports Server (NTRS)

Hansman, R. John; Feron, Eric; Clarke, John-Paul; Odoni, Amedeo

1999-01-01

The objective of the proposed effort is to investigate issues associated with the design and implementation of decision aiding tools to assist in improving the departure process at congested airports. This effort follows a preliminary investigation of potential Departure Planning approaches and strategies, which identified potential benefits in departure efficiency, and also in reducing the environmental impact of aircraft in the departure queue. The preliminary study bas based, in large part, on observations and analysis of departure processes at Boston, Logan airport. The objective of this follow-on effort is to address key implementation issues and to expand the observational base to include airports with different constraints and traffic demand. Specifically, the objectives of this research are to: (1) Expand the observational base to include airports with different underlying operational dynamics. (2) Develop prototype decision aiding algorithms/approaches and assess potential benefits. and (3) Investigate Human Machine Integration (HMI) issues associated with decision aids in tower environments.

EGCG in Green Tea Induces Aggregation of HMGB1 Protein through Large Conformational Changes with Polarized Charge Redistribution

NASA Astrophysics Data System (ADS)

Meng, Xuan-Yu; Li, Baoyu; Liu, Shengtang; Kang, Hongsuk; Zhao, Lin; Zhou, Ruhong

2016-02-01

As a major effective component in green tea, (-)-epigallocatechin-3-gallate (EGCG)’s potential benefits to human health have been widely investigated. Recent experimental evidences indicate that EGCG can induce the aggregation of HMGB1 protein, a late mediator of inflammation, which subsequently stimulates the autophagic degradation and thus provides protection from lethal endotoxemia and sepsis. In this study, we use molecular dynamics (MD) simulations to explore the underlying molecular mechanism of this aggregation of HMGB1 facilitated by EGCG. Our simulation results reveal that EGCG firmly binds to HMGB1 near Cys106, which supports previous preliminary experimental evidence. A large HMGB1 conformational change is observed, where Box A and Box B, two homogenous domains of HMGB1, are repositioned and packed together by EGCG. This new HMGB1 conformation has large molecular polarity and distinctive electrostatic potential surface. We suggest that the highly polarized charge distribution leads to the aggregation of HMGB1, which differs from the previous hypothesis that two HMGB1 monomers are linked by the dimer of EGCG. Possible aggregating modes have also been investigated with potential of mean force (PMF) calculations. Finally, we conclude that the conformation induced by EGCG is more aggregation-prone with higher binding free energies as compared to those without EGCG.

Use of Two-Body Correlated Basis Functions with van der Waals Interaction to Study the Shape-Independent Approximation for a Large Number of Trapped Interacting Bosons

NASA Astrophysics Data System (ADS)

Lekala, M. L.; Chakrabarti, B.; Das, T. K.; Rampho, G. J.; Sofianos, S. A.; Adam, R. M.; Haldar, S. K.

2017-05-01

We study the ground-state and the low-lying excitations of a trapped Bose gas in an isotropic harmonic potential for very small (˜ 3) to very large (˜ 10^7) particle numbers. We use the two-body correlated basis functions and the shape-dependent van der Waals interaction in our many-body calculations. We present an exhaustive study of the effect of inter-atomic correlations and the accuracy of the mean-field equations considering a wide range of particle numbers. We calculate the ground-state energy and the one-body density for different values of the van der Waals parameter C6. We compare our results with those of the modified Gross-Pitaevskii results, the correlated Hartree hypernetted-chain equations (which also utilize the two-body correlated basis functions), as well as of the diffusion Monte Carlo for hard sphere interactions. We observe the effect of the attractive tail of the van der Waals potential in the calculations of the one-body density over the truly repulsive zero-range potential as used in the Gross-Pitaevskii equation and discuss the finite-size effects. We also present the low-lying collective excitations which are well described by a hydrodynamic model in the large particle limit.

Salticid predation as one potential driving force of ant mimicry in jumping spiders

PubMed Central

Huang, Jin-Nan; Cheng, Ren-Chung; Li, Daiqin; Tso, I-Min

2011-01-01

Many spiders possess myrmecomorphy, and species of the jumping spider genus Myrmarachne exhibit nearly perfect ant mimicry. Most salticids are diurnal predators with unusually high visual acuity that prey on various arthropods, including conspecifics. In this study, we tested whether predation pressure from large jumping spiders is one possible driving force of perfect ant mimicry in jumping spiders. The results showed that small non-ant-mimicking jumping spiders were readily treated as prey by large ones (no matter whether heterospecific or conspecific) and suffered high attack and mortality rates. The size difference between small and large jumping spiders significantly affected the outcomes of predatory interactions between them: the smaller the juvenile jumping spiders, the higher the predation risk from large ones. The attack and mortality rates of ant-mimicking jumping spiders were significantly lower than those of non-ant-mimicking jumping spiders, indicating that a resemblance to ants could provide protection against salticid predation. However, results of multivariate behavioural analyses showed that the responses of large jumping spiders to ants and ant-mimicking salticids differed significantly. Results of this study indicate that predation pressure from large jumping spiders might be one selection force driving the evolution of nearly perfect myrmecomorphy in spiders and other arthropods. PMID:20961898

Does source population size affect performance in new environments?

PubMed Central

Yates, Matthew C; Fraser, Dylan J

2014-01-01

Small populations are predicted to perform poorly relative to large populations when experiencing environmental change. To explore this prediction in nature, data from reciprocal transplant, common garden, and translocation studies were compared meta-analytically. We contrasted changes in performance resulting from transplantation to new environments among individuals originating from different sized source populations from plants and salmonids. We then evaluated the effect of source population size on performance in natural common garden environments and the relationship between population size and habitat quality. In ‘home-away’ contrasts, large populations exhibited reduced performance in new environments. In common gardens, the effect of source population size on performance was inconsistent across life-history stages (LHS) and environments. When transplanted to the same set of new environments, small populations either performed equally well or better than large populations, depending on life stage. Conversely, large populations outperformed small populations within native environments, but only at later life stages. Population size was not associated with habitat quality. Several factors might explain the negative association between source population size and performance in new environments: (i) stronger local adaptation in large populations and antagonistic pleiotropy, (ii) the maintenance of genetic variation in small populations, and (iii) potential environmental differences between large and small populations. PMID:25469166

Buccal Swabbing as a Noninvasive Method To Determine Bacterial, Archaeal, and Eukaryotic Microbial Community Structures in the Rumen

PubMed Central

Kirk, Michelle R.; Jonker, Arjan; McCulloch, Alan

2015-01-01

Analysis of rumen microbial community structure based on small-subunit rRNA marker genes in metagenomic DNA samples provides important insights into the dominant taxa present in the rumen and allows assessment of community differences between individuals or in response to treatments applied to ruminants. However, natural animal-to-animal variation in rumen microbial community composition can limit the power of a study considerably, especially when only subtle differences are expected between treatment groups. Thus, trials with large numbers of animals may be necessary to overcome this variation. Because ruminants pass large amounts of rumen material to their oral cavities when they chew their cud, oral samples may contain good representations of the rumen microbiota and be useful in lieu of rumen samples to study rumen microbial communities. We compared bacterial, archaeal, and eukaryotic community structures in DNAs extracted from buccal swabs to those in DNAs from samples collected directly from the rumen by use of a stomach tube for sheep on four different diets. After bioinformatic depletion of potential oral taxa from libraries of samples collected via buccal swabs, bacterial communities showed significant clustering by diet (R = 0.37; analysis of similarity [ANOSIM]) rather than by sampling method (R = 0.07). Archaeal, ciliate protozoal, and anaerobic fungal communities also showed significant clustering by diet rather than by sampling method, even without adjustment for potentially orally associated microorganisms. These findings indicate that buccal swabs may in future allow quick and noninvasive sampling for analysis of rumen microbial communities in large numbers of ruminants. PMID:26276109

Variation in the population structure of Yukon River chum and coho salmon: Evaluating the potential impact of localized habitat degradation

USGS Publications Warehouse

Olsen, J.B.; Spearman, William J.; Sage, G.K.; Miller, S.J.; Flannery, B.G.; Wenburg, J.K.

2004-01-01

We used microsatellite and mitochondrial DNA-restriction fragment length polymorphism (mtDNA-RFLP) analyses to test the hypothesis that chum salmon Oncorhynchus keta and coho salmon O. kisutch in the Yukon River, Alaska, exhibit population structure at differing spatial scales. If the hypothesis is true, then the risk of losing genetic diversity because of habitat degradation from a gold mine near a Yukon River tributary could differ between the two species. For each species, collections were made from two tributaries in both the Innoko and Tanana rivers, which are tributaries to the lower and middle Yukon River. The results revealed a large difference in the degree and spatial distribution of population structure between the two species. For chum salmon, the microsatellite loci (F-statistic [FST] = 0.021) and mtDNA (F ST = -0.008) revealed a low degree of interpopulation genetic diversity on a relatively large geographic scale. This large-scale population structure should minimize, although not eliminate, the risk of genetic diversity loss due to localized habitat degradation. For coho salmon, the microsatellites (FST = 0.091) and mtDNA (FST = 0.586) revealed a high degree of interpopulation genetic diversity on a relatively small geographic scale. This small-scale population structure suggests that coho salmon are at a relatively high risk of losing genetic diversity due to lo-calized habitat degradation. Our study underscores the importance of a multispecies approach for evaluating the potential impact of land-use activities on the genetic diversity of Pacific salmon.

Feedback-related negativity in children with two subtypes of attention deficit hyperactivity disorder.

PubMed

Gong, Jingbo; Yuan, Jiajin; Wang, Suhong; Shi, Lijuan; Cui, Xilong; Luo, Xuerong

2014-01-01

The current model of ADHD suggests abnormal reward and punishment sensitivity, although differences in ADHD subgroups are unclear. This study aimed to investigate the effect of feedback valence (reward or punishment) and punishment magnitude (small or large) on Feedback-Related Negativity (FRN) and Late Positive Potential (LPP) in two subtypes of ADHD (ADHD-C and ADHD-I) compared to typically developing children (TD) during a children's gambling task. Children with ADHD-C (n = 16), children with ADHD-I (n = 15) and typically developing children (n = 15) performed a children's gambling task under three feedback conditions: large losses, small losses and gains. FRN and LPP components in brain potentials were recorded and analyzed. In TD children and children with ADHD-C, large loss feedback evoked more negative FRN amplitudes than small loss feedback, suggesting that brain sensitivity to the punishment and its magnitude is not impaired in children with ADHD-C. In contrast to these two groups, the FRN effect was absent in children with ADHD-I. The LPP amplitudes were larger in children with ADHD-C in comparison with those with ADHD-I, regardless of feedback valence and magnitude. Children with ADHD-C exhibit intact brain sensitivity to punishment similar to TD children. In contrast, children with ADHD-I are significantly impaired in neural sensitivity to the feedback stimuli and in particular, to punishment, compared to TD and ADHD-C children. Thus, FRN, rather than LPP, is a reliable index of the difference in reward and punishment sensitivity across different ADHD-subcategories.

Fine resolution map of top- and subsoil carbon sequestration potential in France.

PubMed

Chen, Songchao; Martin, Manuel P; Saby, Nicolas P A; Walter, Christian; Angers, Denis A; Arrouays, Dominique

2018-07-15

Although soils have a high potential to offset CO 2 emissions through its conversion into soil organic carbon (SOC) with long turnover time, it is widely accepted that there is an upper limit of soil stable C storage, which is referred to SOC saturation. In this study we estimate SOC saturation in French topsoil (0-30cm) and subsoil (30-50cm), using the Hassink equation and calculate the additional SOC sequestration potential (SOC sp ) by the difference between SOC saturation and fine fraction C on an unbiased sampling set of sites covering whole mainland France. We then map with fine resolution the geographical distribution of SOC sp over the French territory using a regression Kriging approach with environmental covariates. Results show that the controlling factors of SOC sp differ from topsoil and subsoil. The main controlling factor of SOCsp in topsoils is land use. Nearly half of forest topsoils are over-saturated with a SOC sp close to 0 (mean and standard error at 0.19±0.12) whereas cropland, vineyard and orchard soils are largely unsaturated with degrees of C saturation deficit at 36.45±0.68% and 57.10±1.64%, respectively. The determinant of C sequestration potential in subsoils is related to parent material. There is a large additional SOC sp in subsoil for all land uses with degrees of C saturation deficit between 48.52±4.83% and 68.68±0.42%. Overall the SOCsp for French soils appears to be very large (1008Mt C for topsoil and 1360Mt C for subsoil) when compared to previous total SOC stocks estimates of about 3.5Gt in French topsoil. Our results also show that overall, 176Mt C exceed C saturation in French topsoil and might thus be very sensitive to land use change. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

Climate-driven geographic distribution of the desert locust during recession periods: Subspecies' niche differentiation and relative risks under scenarios of climate change.

PubMed

Meynard, Christine N; Gay, Pierre-Emmanuel; Lecoq, Michel; Foucart, Antoine; Piou, Cyril; Chapuis, Marie-Pierre

2017-11-01

The desert locust is an agricultural pest that is able to switch from a harmless solitarious stage, during recession periods, to swarms of gregarious individuals that disperse long distances and affect areas from western Africa to India during outbreak periods. Large outbreaks have been recorded through centuries, and the Food and Agriculture Organization keeps a long-term, large-scale monitoring survey database in the area. However, there is also a much less known subspecies that occupies a limited area in Southern Africa. We used large-scale climatic and occurrence data of the solitarious phase of each subspecies during recession periods to understand whether both subspecies climatic niches differ from each other, what is the current potential geographical distribution of each subspecies, and how climate change is likely to shift their potential distribution with respect to current conditions. We evaluated whether subspecies are significantly specialized along available climate gradients by using null models of background climatic differences within and between southern and northern ranges and applying niche similarity and niche equivalency tests. The results point to climatic niche conservatism between the two clades. We complemented this analysis with species distribution modeling to characterize current solitarious distributions and forecast potential recession range shifts under two extreme climate change scenarios at the 2050 and 2090 time horizon. Projections suggest that, at a global scale, the northern clade could contract its solitarious recession range, while the southern clade is likely to expand its recession range. However, local expansions were also predicted in the northern clade, in particular in southern and northern margins of the current geographical distribution. In conclusion, monitoring and management practices should remain in place in northern Africa, while in Southern Africa the potential for the subspecies to pose a threat in the future should be investigated more closely. © 2017 John Wiley & Sons Ltd.

'Long-Cell Action' Corrosion: A Basic Mechanism Hidden Behind Components Degradation Issues in Nuclear Power Plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genn Saji

2006-07-01

In spite of industries' effort over the last 40 years, corrosion-related issues continue to be one of the largest unresolved problems for nuclear power plants worldwide. There are several types of strange corrosion phenomena from the point of view of our current understanding of corrosion science established in other fields. Some of these are IGSCC, PWSCC, AOA, and FAC (Erosion-Corrosion). Through studying and coping with diverse corrosion phenomena, the author believes that they share a common basis with respect to the assumed corrosion mechanism (e.g., 'local cell action' hypothesis). In general, local cell action is rarely severe since it producesmore » a fairly uniform corrosion. The 'long cell action' that transports electrons through structures far beyond the region of local cell corrosion activities has been identified as a basic mechanism in soil corrosion. If this mechanism is assumed in nuclear power plants, the structure becomes anodic in the area where the potential is less positive and cathodic where this potential is more positive. Metallic ions generated at anodic corrosion sites are transported to remote cathodic sites through the circulation of water and deposits as corrosion products. The SCC, FAC (E-C) and PWSCC occur in the anodic sites as the structure itself acts as a short-circuiting conductor between the two sites, the action is similar to a galvanic cell but in a very large scale. This situation is the same as a battery that has been short-circuited at the terminals. No apparent external potential difference exists between the two electrodes, but an electrochemical reaction is still taking place inside the battery cell with a large internal short current. In this example what is important is the potential difference between the local coolant and the surface of the structural material. Long cell action corrosion is likely enhancing the local cell action's anodic corrosion activities, such as SCC, FAC/E-C, and PWSCC. It tends to be more hazardous because of its localized nature compared with the local cell action corrosion. There exist various mechanisms (electrochemical cell configurations) that induce such potential differences, including: ionic concentration, aeration, temperature, flow velocity, radiation and corrosion potentials. In this paper, the author will discuss these potential differences and their relevance to the un-resolved corrosion issues in nuclear power plants. Due to the importance of this potential mechanism the author is calling for further verification experiments as a joint international project. (author)« less

Techniques for automatic large scale change analysis of temporal multispectral imagery

NASA Astrophysics Data System (ADS)

Mercovich, Ryan A.

Change detection in remotely sensed imagery is a multi-faceted problem with a wide variety of desired solutions. Automatic change detection and analysis to assist in the coverage of large areas at high resolution is a popular area of research in the remote sensing community. Beyond basic change detection, the analysis of change is essential to provide results that positively impact an image analyst's job when examining potentially changed areas. Present change detection algorithms are geared toward low resolution imagery, and require analyst input to provide anything more than a simple pixel level map of the magnitude of change that has occurred. One major problem with this approach is that change occurs in such large volume at small spatial scales that a simple change map is no longer useful. This research strives to create an algorithm based on a set of metrics that performs a large area search for change in high resolution multispectral image sequences and utilizes a variety of methods to identify different types of change. Rather than simply mapping the magnitude of any change in the scene, the goal of this research is to create a useful display of the different types of change in the image. The techniques presented in this dissertation are used to interpret large area images and provide useful information to an analyst about small regions that have undergone specific types of change while retaining image context to make further manual interpretation easier. This analyst cueing to reduce information overload in a large area search environment will have an impact in the areas of disaster recovery, search and rescue situations, and land use surveys among others. By utilizing a feature based approach founded on applying existing statistical methods and new and existing topological methods to high resolution temporal multispectral imagery, a novel change detection methodology is produced that can automatically provide useful information about the change occurring in large area and high resolution image sequences. The change detection and analysis algorithm developed could be adapted to many potential image change scenarios to perform automatic large scale analysis of change.

Drivers and seasonal predictability of extreme wind speeds in the ECMWF System 4 and a statistical model

NASA Astrophysics Data System (ADS)

Walz, M. A.; Donat, M.; Leckebusch, G. C.

2017-12-01

As extreme wind speeds are responsible for large socio-economic losses in Europe, a skillful prediction would be of great benefit for disaster prevention as well as for the actuarial community. Here we evaluate patterns of large-scale atmospheric variability and the seasonal predictability of extreme wind speeds (e.g. >95th percentile) in the European domain in the dynamical seasonal forecast system ECMWF System 4, and compare to the predictability based on a statistical prediction model. The dominant patterns of atmospheric variability show distinct differences between reanalysis and ECMWF System 4, with most patterns in System 4 extended downstream in comparison to ERA-Interim. The dissimilar manifestations of the patterns within the two models lead to substantially different drivers associated with the occurrence of extreme winds in the respective model. While the ECMWF System 4 is shown to provide some predictive power over Scandinavia and the eastern Atlantic, only very few grid cells in the European domain have significant correlations for extreme wind speeds in System 4 compared to ERA-Interim. In contrast, a statistical model predicts extreme wind speeds during boreal winter in better agreement with the observations. Our results suggest that System 4 does not seem to capture the potential predictability of extreme winds that exists in the real world, and therefore fails to provide reliable seasonal predictions for lead months 2-4. This is likely related to the unrealistic representation of large-scale patterns of atmospheric variability. Hence our study points to potential improvements of dynamical prediction skill by improving the simulation of large-scale atmospheric dynamics.

Parameterization Interactions in Global Aquaplanet Simulations

NASA Astrophysics Data System (ADS)

Bhattacharya, Ritthik; Bordoni, Simona; Suselj, Kay; Teixeira, João.

2018-02-01

Global climate simulations rely on parameterizations of physical processes that have scales smaller than the resolved ones. In the atmosphere, these parameterizations represent moist convection, boundary layer turbulence and convection, cloud microphysics, longwave and shortwave radiation, and the interaction with the land and ocean surface. These parameterizations can generate different climates involving a wide range of interactions among parameterizations and between the parameterizations and the resolved dynamics. To gain a simplified understanding of a subset of these interactions, we perform aquaplanet simulations with the global version of the Weather Research and Forecasting (WRF) model employing a range (in terms of properties) of moist convection and boundary layer (BL) parameterizations. Significant differences are noted in the simulated precipitation amounts, its partitioning between convective and large-scale precipitation, as well as in the radiative impacts. These differences arise from the way the subcloud physics interacts with convection, both directly and through various pathways involving the large-scale dynamics and the boundary layer, convection, and clouds. A detailed analysis of the profiles of the different tendencies (from the different physical processes) for both potential temperature and water vapor is performed. While different combinations of convection and boundary layer parameterizations can lead to different climates, a key conclusion of this study is that similar climates can be simulated with model versions that are different in terms of the partitioning of the tendencies: the vertically distributed energy and water balances in the tropics can be obtained with significantly different profiles of large-scale, convection, and cloud microphysics tendencies.

Implanted neural network potentials: Application to Li-Si alloys

NASA Astrophysics Data System (ADS)

Onat, Berk; Cubuk, Ekin D.; Malone, Brad D.; Kaxiras, Efthimios

2018-03-01

Modeling the behavior of materials composed of elements with different bonding and electronic structure character for large spatial and temporal scales and over a large compositional range is a challenging problem. Cases in point are amorphous alloys of Si, a prototypical covalent material, and Li, a prototypical metal, which are being considered as anodes for high-energy-density batteries. To address this challenge, we develop a methodology based on neural networks that extends the conventional training approach to incorporate pre-trained parts that capture the character of different components, into the overall network; we refer to this model as the "implanted neural network" method. We show that this approach works well for the Si-Li amorphous alloys for a wide range of compositions, giving good results for key quantities like the diffusion coefficients. The method is readily generalizable to more complicated situations that involve two or more different elements.

Uncertainty in flood damage estimates and its potential effect on investment decisions

NASA Astrophysics Data System (ADS)

Wagenaar, Dennis; de Bruijn, Karin; Bouwer, Laurens; de Moel, Hans

2015-04-01

This paper addresses the large differences that are found between damage estimates of different flood damage models. It explains how implicit assumptions in flood damage models can lead to large uncertainties in flood damage estimates. This explanation is used to quantify this uncertainty with a Monte Carlo Analysis. This Monte Carlo analysis uses a damage function library with 272 functions from 7 different flood damage models. This results in uncertainties in the order of magnitude of a factor 2 to 5. This uncertainty is typically larger for small water depths and for smaller flood events. The implications of the uncertainty in damage estimates for flood risk management are illustrated by a case study in which the economic optimal investment strategy for a dike segment in the Netherlands is determined. The case study shows that the uncertainty in flood damage estimates can lead to significant over- or under-investments.

Uncertainty in flood damage estimates and its potential effect on investment decisions

NASA Astrophysics Data System (ADS)

Wagenaar, D. J.; de Bruijn, K. M.; Bouwer, L. M.; De Moel, H.

2015-01-01

This paper addresses the large differences that are found between damage estimates of different flood damage models. It explains how implicit assumptions in flood damage models can lead to large uncertainties in flood damage estimates. This explanation is used to quantify this uncertainty with a Monte Carlo Analysis. As input the Monte Carlo analysis uses a damage function library with 272 functions from 7 different flood damage models. This results in uncertainties in the order of magnitude of a factor 2 to 5. The resulting uncertainty is typically larger for small water depths and for smaller flood events. The implications of the uncertainty in damage estimates for flood risk management are illustrated by a case study in which the economic optimal investment strategy for a dike segment in the Netherlands is determined. The case study shows that the uncertainty in flood damage estimates can lead to significant over- or under-investments.

Fast adaptive flat-histogram ensemble to enhance the sampling in large systems

NASA Astrophysics Data System (ADS)

Xu, Shun; Zhou, Xin; Jiang, Yi; Wang, YanTing

2015-09-01

An efficient novel algorithm was developed to estimate the Density of States (DOS) for large systems by calculating the ensemble means of an extensive physical variable, such as the potential energy, U, in generalized canonical ensembles to interpolate the interior reverse temperature curve , where S( U) is the logarithm of the DOS. This curve is computed with different accuracies in different energy regions to capture the dependence of the reverse temperature on U without setting prior grid in the U space. By combining with a U-compression transformation, we decrease the computational complexity from O( N 3/2) in the normal Wang Landau type method to O( N 1/2) in the current algorithm, as the degrees of freedom of system N. The efficiency of the algorithm is demonstrated by applying to Lennard Jones fluids with various N, along with its ability to find different macroscopic states, including metastable states.

Neutrinoless Double Beta Decay Matrix Elements in Light Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pastore, S.; Carlson, J.; Cirigliano, V.

We present the first ab initio calculations of neutrinoless double-β decay matrix elements in A=6-12 nuclei using variational Monte Carlo wave functions obtained from the Argonne v 18 two-nucleon potential and Illinois-7 three-nucleon interaction. We study both light Majorana neutrino exchange and potentials arising from a large class of multi-TeV mechanisms of lepton-number violation. Our results provide benchmarks to be used in testing many-body methods that can be extended to the heavy nuclei of experimental interest. In light nuclei we also study the impact of two-body short-range correlations and the use of different forms for the transition operators, such asmore » those corresponding to different orders in chiral effective theory.« less

Uranium phase diagram from first principles

NASA Astrophysics Data System (ADS)

Yanilkin, Alexey; Kruglov, Ivan; Migdal, Kirill; Oganov, Artem; Pokatashkin, Pavel; Sergeev, Oleg

2017-06-01

The work is devoted to the investigation of uranium phase diagram up to pressure of 1 TPa and temperature of 15 kK based on density functional theory. First of all the comparison of pseudopotential and full potential calculations is carried out for different uranium phases. In the second step, phase diagram at zero temperature is investigated by means of program USPEX and pseudopotential calculations. Stable and metastable structures with close energies are selected. In order to obtain phase diagram at finite temperatures the preliminary selection of stable phases is made by free energy calculation based on small displacement method. For remaining candidates the accurate values of free energy are obtained by means of thermodynamic integration method (TIM). For this purpose quantum molecular dynamics are carried out at different volumes and temperatures. Interatomic potentials based machine learning are developed in order to consider large systems and long times for TIM. The potentials reproduce the free energy with the accuracy 1-5 meV/atom, which is sufficient for prediction of phase transitions. The equilibrium curves of different phases are obtained based on free energies. Melting curve is calculated by modified Z-method with developed potential.

Validation Results for LEWICE 3.0

NASA Technical Reports Server (NTRS)

Wright, William B.

2005-01-01

A research project is underway at NASA Glenn to produce computer software that can accurately predict ice growth under any meteorological conditions for any aircraft surface. This report will present results from version 3.0 of this software, which is called LEWICE. This version differs from previous releases in that it incorporates additional thermal analysis capabilities, a pneumatic boot model, interfaces to computational fluid dynamics (CFD) flow solvers and has an empirical model for the supercooled large droplet (SLD) regime. An extensive comparison of the results in a quantifiable manner against the database of ice shapes and collection efficiency that have been generated in the NASA Glenn Icing Research Tunnel (IRT) has also been performed. The complete set of data used for this comparison will eventually be available in a contractor report. This paper will show the differences in collection efficiency between LEWICE 3.0 and experimental data. Due to the large amount of validation data available, a separate report is planned for ice shape comparison. This report will first describe the LEWICE 3.0 model for water collection. A semi-empirical approach was used to incorporate first order physical effects of large droplet phenomena into icing software. Comparisons are then made to every single element two-dimensional case in the water collection database. Each condition was run using the following five assumptions: 1) potential flow, no splashing; 2) potential flow, no splashing with 21 bin drop size distributions and a lift correction (angle of attack adjustment); 3) potential flow, with splashing; 4) Navier-Stokes, no splashing; and 5) Navier-Stokes, with splashing. Quantitative comparisons are shown for impingement limit, maximum water catch, and total collection efficiency. The results show that the predicted results are within the accuracy limits of the experimental data for the majority of cases.

Sensitivity of Asteroid Impact Risk to Uncertainty in Asteroid Properties and Entry Parameters

NASA Astrophysics Data System (ADS)

Wheeler, Lorien; Mathias, Donovan; Dotson, Jessie L.; NASA Asteroid Threat Assessment Project

2017-10-01

A central challenge in assessing the threat posed by asteroids striking Earth is the large amount of uncertainty inherent throughout all aspects of the problem. Many asteroid properties are not well characterized and can range widely from strong, dense, monolithic irons to loosely bound, highly porous rubble piles. Even for an object of known properties, the specific entry velocity, angle, and impact location can swing the potential consequence from no damage to causing millions of casualties. Due to the extreme rarity of large asteroid strikes, there are also large uncertainties in how different types of asteroids will interact with the atmosphere during entry, how readily they may break up or ablate, and how much surface damage will be caused by the resulting airbursts or impacts.In this work, we use our Probabilistic Asteroid Impact Risk (PAIR) model to investigate the sensitivity of asteroid impact damage to uncertainties in key asteroid properties, entry parameters, or modeling assumptions. The PAIR model combines physics-based analytic models of asteroid entry and damage in a probabilistic Monte Carlo framework to assess the risk posed by a wide range of potential impacts. The model samples from uncertainty distributions of asteroid properties and entry parameters to generate millions of specific impact cases, and models the atmospheric entry and damage for each case, including blast overpressure, thermal radiation, tsunami inundation, and global effects. To assess the risk sensitivity, we alternately fix and vary the different input parameters and compare the effect on the resulting range of damage produced. The goal of these studies is to help guide future efforts in asteroid characterization and model refinement by determining which properties most significantly affect the potential risk.

Bio inspired Magnet-polymer (Magpol) actuators

NASA Astrophysics Data System (ADS)

Ahmed, Anansa S.; Ramanujan, R. V.

2014-03-01

Magnet filler-polymer matrix composites (Magpol) are an emerging class of morphing materials. Magpol composites have an interesting ability to undergo large strains in response to an external magnetic field. The potential to develop Magpol as large strain actuators is due to the ability to incorporate large particle loading into the composite and also due to the increased interaction area at the interface of the nanoparticles and the composite. Mn-Zn ferrite fillers with different saturation magnetizations (Ms) were synthesized. Magpol composites consisting of magnetic ferrite filler particles in an Poly ethylene vinyl acetate (EVA) matrix were prepared. The deformation characteristics of the actuator were determined. The morphing ability of the Magpol composite was studied under different magnetic fields and also with different filler loadings. All films exhibited large strain under the applied magnetic field. The maximum strain of the composite showed an exponential dependence on the Ms. The work output of Magpol was also calculated using the work loop method. Work densities of upto 1 kJ/m3 were obtained which can be compared to polypyrrole actuators, but with almost double the typical strain. Applications of Magpol can include artificial muscles, drug delivery, adaptive optics and self healing structures. Advantages of Magpol include remote contactless actuation, high actuation strain and strain rate and quick response.

Taking OSCE examiner training on the road: reaching the masses.

PubMed

Reid, Katharine; Smallwood, David; Collins, Margo; Sutherland, Ruth; Dodds, Agnes

To ensure the rigour of objective structured clinical examinations (OSCEs) in assessing medical students, medical school educators must educate examiners with a view to standardising examiner assessment behaviour. Delivering OSCE examiner training is a necessary yet challenging part of the OSCE process. A novel approach to implementing training for current and potential OSCE examiners was trialled by delivering large-group education sessions at major teaching hospitals. The 'OSCE Roadshow' comprised a short training session delivered in the context of teaching hospital 'Grand Rounds' to current and potential OSCE examiners. The training was developed to educate clinicians about OSCE processes, clarify the examiners' role and required behaviours, and to review marking guides and mark allocation in an effort to standardise OSCE processes and encourage consistency in examiner marking behaviour. A short exercise allowed participants to practise marking a mock OSCE to investigate examiner marking behaviour after the training. OSCE Roadshows at four metropolitan and one rural teaching hospital were well received and well attended by 171 clinicians across six sessions. Unexpectedly, medical students also attended in large numbers ( n= 220). After training, participants' average scores for the mock OSCE clustered closely around the ideal score of 28 (out of 40), and the average scores did not differ according to the levels of clinical experience. The OSCE Roadshow demonstrated the potential of brief familiarisation training in reaching large numbers of current and potential OSCE examiners in a time and cost-effective manner to promote standardisation of OSCE processes.

Taking OSCE examiner training on the road: reaching the masses.

PubMed

Reid, Katharine; Smallwood, David; Collins, Margo; Sutherland, Ruth; Dodds, Agnes

2016-01-01

Background To ensure the rigour of objective structured clinical examinations (OSCEs) in assessing medical students, medical school educators must educate examiners with a view to standardising examiner assessment behaviour. Delivering OSCE examiner training is a necessary yet challenging part of the OSCE process. A novel approach to implementing training for current and potential OSCE examiners was trialled by delivering large-group education sessions at major teaching hospitals. Methods The 'OSCE Roadshow' comprised a short training session delivered in the context of teaching hospital 'Grand Rounds' to current and potential OSCE examiners. The training was developed to educate clinicians about OSCE processes, clarify the examiners' role and required behaviours, and to review marking guides and mark allocation in an effort to standardise OSCE processes and encourage consistency in examiner marking behaviour. A short exercise allowed participants to practise marking a mock OSCE to investigate examiner marking behaviour after the training. Results OSCE Roadshows at four metropolitan and one rural teaching hospital were well received and well attended by 171 clinicians across six sessions. Unexpectedly, medical students also attended in large numbers (n=220). After training, participants' average scores for the mock OSCE clustered closely around the ideal score of 28 (out of 40), and the average scores did not differ according to the levels of clinical experience. Conclusion The OSCE Roadshow demonstrated the potential of brief familiarisation training in reaching large numbers of current and potential OSCE examiners in a time and cost-effective manner to promote standardisation of OSCE processes.

The Perceived Impact of Unstable Gaps between Academic Ability and Performance on the Self-Image of Students with Learning Disabilities

ERIC Educational Resources Information Center

Einat, Amela

2017-01-01

Disparities among the different abilities of students with learning disabilities have attracted extensive research. The attention has largely focused on how low abilities mask good or high potential intellectual level, and the resulting frustration. Correspondingly, the literature has also concentrated on the methods of detection required to…

Migrating Learning Management Systems: A Case of a Large Public University

ERIC Educational Resources Information Center

Such, Brenda L. R.; Ritzhaupt, Albert D.; Thompson, George S.

2017-01-01

In the past 20 years, institutions of higher education have made major investments in Learning Management Systems (LMSs). As institutions have integrated the LMS into campus culture, the potential of migrating to not only an upgraded version of the LMS, but also an entirely different LMS, has become a reality. This qualitative research study…

Growth and gas exchange of different ponderosa pine stock types on dry sites

Treesearch

Jeremiah Ray Pinto

2009-01-01

Successful seedling establishment following outplanting relies heavily on a seedling's ability to access soil moisture. In the Inland Northwest USA, the summer season brings drought conditions causing low soil moisture in the upper soil profile - a potentially large barrier to seedling establishment. During the 2007 growing season, three studies examined the...

Evaluating Differences in Landscape Interpretation between Webcam and Field-Based Experiences

ERIC Educational Resources Information Center

Kolivras, Korine N.; Luebbering, Candice R.; Resler, Lynn M.

2012-01-01

Field trips have become less common due to issues including budget constraints and large class sizes. Research suggests that virtual field trips can substitute for field visits, but the role of webcams has not been evaluated. To investigate the potential for webcams to substitute for field trips, participants viewed urban and physical landscapes…

Cultural Differences in the Relationship between Perceived Family Environments and Self-Determination among Students with Disabilities

ERIC Educational Resources Information Center

Rodriguez, Raymond J.; Cavendish, Wendy

2013-01-01

This study examined the potential role of cultural variables in the relationship between perceived family environments and levels of self-determination among students with disabilities. Participants were 190 Latino, African-American and Euro-American students with disabilities enrolled in six high schools within a large urban school district in…

A feed-forward neural network for modeling feeding behavior of group-housed grow-finish pigs with respect to thermal conditions

USDA-ARS?s Scientific Manuscript database

Feeding patterns of pigs in the grow-finish phase have been investigated for use in management decisions, identifying sick animals, and determining genetic differences within a herd. Development of models to predict swine feeding behavior has been limited due the large number of potential environmen...

The Potential of Modelling Co-Teaching in Pre-Service Education

ERIC Educational Resources Information Center

Drescher, Talya

2017-01-01

Two studies aimed to document the process of preparing for and teaching collaborative education courses and to determine students' perception of collaboration and inclusion as a result of taking the course. Two sessions of collaborative teaching run by different professor dyads were studied over two 10-week quarters at a large public university.…

Phenotypic Characteristics of Autism Spectrum Disorder in a Diverse Sample of Somali and Other Children

ERIC Educational Resources Information Center

Esler, Amy N.; Hall-Lande, Jennifer; Hewitt, Amy

2017-01-01

The potential for culture to impact diagnosis of autism spectrum disorder (ASD) is high, yet remains largely unstudied. This study examined differences across racial/ethnic groups in ASD symptoms, cognitive and adaptive skills, and related behaviors in children with ASD that included a unique subgroup, children from the Somali diaspora. Somali…

Better almond water stress monitoring using fractional-order moments of non-normalized difference vegetation index

USDA-ARS?s Scientific Manuscript database

Stem water potential (SWP) has become a very popular tool for farmers to monitor the water status of almond trees. However, it is labor intensive and time consuming to scale up the measurements in the large field. With the development of unmanned aerial vehicles (UAVs) and sensing payload, it become...

Interhemispheric differences and solar cycle effects of the high-latitude ionospheric convection patterns deduced from Cluster EDI observations

NASA Astrophysics Data System (ADS)

Förster, Matthias; Haaland, Stein

2015-04-01

Here, we present a study of ionospheric convection at high latitudes that is based on satellite measurements of the Electron Drift Instrument (EDI) on-board the Cluster satellites, which were obtained over a full solar cycle (2001-2013). The mapped drift measurements are covering both hemispheres and a variety of different solar wind and interplanetary magnetic field (IMF) conditions. The large amount of data allows us to perform more detailed statistical studies. We show that flow patterns and polar cap potentials can differ between the two hemispheres on statistical average for a given IMF orientation. In particular, during southward directed IMF conditions, and thus enhanced energy input from the solar wind, we find that the southern polar cap has a higher cross polar cap potential. We also find persistent north-south asymmetries which cannot be explained by external drivers alone. Much of these asymmetries can probably be explained by significant differences in the strength and configuration of the geomagnetic field between the Northern and Southern Hemisphere. Since the ionosphere is magnetically connected to the magnetosphere, this difference will also be reflected in the magnetosphere in the form of different feedback from the two hemispheres. Consequently, local ionospheric conditions and the geomagnetic field configuration are important for north-south asymmetries in large regions of geospace. The average convection is higher during periods with high solar activity. Although local ionospheric conditions may play a role, we mainly attribute this to higher geomagnetic activity due to enhanced solar wind - magnetosphere interactions.

Neural Systems Underlying Individual Differences in Intertemporal Decision-making.

PubMed

Elton, Amanda; Smith, Christopher T; Parrish, Michael H; Boettiger, Charlotte A

2017-03-01

Excessively choosing immediate over larger future rewards, or delay discounting (DD), associates with multiple clinical conditions. Individual differences in DD likely depend on variations in the activation of and functional interactions between networks, representing possible endophenotypes for associated disorders, including alcohol use disorders (AUDs). Numerous fMRI studies have probed the neural bases of DD, but investigations of large-scale networks remain scant. We addressed this gap by testing whether activation within large-scale networks during Now/Later decision-making predicts individual differences in DD. To do so, we scanned 95 social drinkers (18-40 years old; 50 women) using fMRI during hypothetical choices between small monetary amounts available "today" or larger amounts available later. We identified neural networks engaged during Now/Later choice using independent component analysis and tested the relationship between component activation and degree of DD. The activity of two components during Now/Later choice correlated with individual DD rates: A temporal lobe network positively correlated with DD, whereas a frontoparietal-striatal network negatively correlated with DD. Activation differences between these networks predicted individual differences in DD, and their negative correlation during Now/Later choice suggests functional competition. A generalized psychophysiological interactions analysis confirmed a decrease in their functional connectivity during decision-making. The functional connectivity of these two networks negatively correlates with alcohol-related harm, potentially implicating these networks in AUDs. These findings provide novel insight into the neural underpinnings of individual differences in impulsive decision-making with potential implications for addiction and related disorders in which impulsivity is a defining feature.

Diagnosing prosopagnosia in East Asian individuals: Norms for the Cambridge Face Memory Test-Chinese.

PubMed

McKone, Elinor; Wan, Lulu; Robbins, Rachel; Crookes, Kate; Liu, Jia

2017-07-01

The Cambridge Face Memory Test (CFMT) is widely accepted as providing a valid and reliable tool in diagnosing prosopagnosia (inability to recognize people's faces). Previously, large-sample norms have been available only for Caucasian-face versions, suitable for diagnosis in Caucasian observers. These are invalid for observers of different races due to potentially severe other-race effects. Here, we provide large-sample norms (N = 306) for East Asian observers on an Asian-face version (CFMT-Chinese). We also demonstrate methodological suitability of the CFMT-Chinese for prosopagnosia diagnosis (high internal reliability, approximately normal distribution, norm-score range sufficiently far above chance). Additional findings were a female advantage on mean performance, plus a difference between participants living in the East (China) or the West (international students, second-generation children of immigrants), which we suggest might reflect personality differences associated with willingness to emigrate. Finally, we demonstrate suitability of the CFMT-Chinese for individual differences studies that use correlations within the normal range.

Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display.

PubMed

Lusk, Christopher H; Pérez-Millaqueo, Manuel M; Saldaña, Alfredo; Burns, Bruce R; Laughlin, Daniel C; Falster, Daniel S

2012-07-01

The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings' initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers. This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LAR(d)) was used to indicate plant light interception potential: LAR(d) is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle. Angiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LAR(d) was about twice that of conifers. Although specific leaf area was the most pervasive influence on LAR(d), differences in self-shading also significantly influenced LAR(d) of large seedlings. The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition.

Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display

PubMed Central

Lusk, Christopher H.; Pérez-Millaqueo, Manuel M.; Saldaña, Alfredo; Burns, Bruce R.; Laughlin, Daniel C.; Falster, Daniel S.

2012-01-01

Background and Aims The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings' initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers. Methods This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LARd) was used to indicate plant light interception potential: LARd is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle. Results Angiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LARd was about twice that of conifers. Although specific leaf area was the most pervasive influence on LARd, differences in self-shading also significantly influenced LARd of large seedlings. Conclusions The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition. PMID:22585929

Calculating the Bending Modulus for Multicomponent Lipid Membranes in Different Thermodynamic Phases

PubMed Central

2013-01-01

We establish a computational approach to extract the bending modulus, KC, for lipid membranes from relatively small-scale molecular simulations. Fluctuations in the splay of individual pairs of lipids faithfully inform on KC in multicomponent membranes over a large range of rigidities in different thermodynamic phases. Predictions are validated by experiments even where the standard spectral analysis-based methods fail. The local nature of this method potentially allows its extension to calculations of KC in protein-laden membranes. PMID:24039553

Mutual information based feature selection for medical image retrieval

NASA Astrophysics Data System (ADS)

Zhi, Lijia; Zhang, Shaomin; Li, Yan

2018-04-01

In this paper, authors propose a mutual information based method for lung CT image retrieval. This method is designed to adapt to different datasets and different retrieval task. For practical applying consideration, this method avoids using a large amount of training data. Instead, with a well-designed training process and robust fundamental features and measurements, the method in this paper can get promising performance and maintain economic training computation. Experimental results show that the method has potential practical values for clinical routine application.

Impact desolvation of electrosprayed microdroplets--a new ionization method for mass spectrometry of large biomolecules.

PubMed

Aksyonov, S A; Williams, P

2001-01-01

Impact desolvation of electrosprayed microdroplets (IDEM) is a new method for producing gas-phase ions of large biomolecules. Analytes are dissolved in an electrolyte solution which is electrosprayed in vacuum, producing highly charged micron and sub-micron sized droplets (microdroplets). These microdroplets are accelerated through potential differences approximately 5 - 10 kV to velocities of several km/s and allowed to impact a target surface. The energetic impacts vaporize the droplets and release desolvated gas-phase ions of the analyte molecules. Oligonucleotides (2- to 12-mer) and peptides (bradykinin, neurotensin) yield singly and doubly charged molecular ions with no detectable fragmentation. Because the extent of multiple charging is significantly less than in atmospheric pressure electrospray ionization, and the method produces ions largely free of adducts from solutions of high ionic strength, IDEM has some promise as a method for coupling to liquid chromatographic techniques and for mixture analysis. Ions are produced in vacuum at a flat equipotential surface, potentially allowing efficient ion extraction. Copyright 2001 John Wiley & Sons, Ltd.

Spatial dynamics of large-scale, multistage crab (Callinectes sapidus) dispersal: Determinants and consequences for recruitment

USGS Publications Warehouse

Etherington, L.L.; Eggleston, D.B.

2003-01-01

We assessed determinants and consequences of multistage dispersal on spatial recruitment of the blue crab, Callinectes sapidus, within the Croatan, Albemarle, Pamlico Estuarine System (CAPES), North Carolina, U.S.A. Large-scale sampling of early juvenile crabs over 4 years indicated that spatial abundance patterns were size-dependent and resulted from primary post-larval dispersal (pre-settlement) and secondary juvenile dispersal (early post-settlement). In general, primary dispersal led to high abundances within more seaward habitats, whereas secondary dispersal (which was relatively consistent) expanded the distribution of juveniles, potentially increasing the estuarine nursery capacity. There were strong relationships between juvenile crab density and specific wind characteristics; however, these patterns were spatially explicit. Various physical processes (e.g., seasonal wind events, timing and magnitude of tropical cyclones) interacted to influence dispersal during multiple stages and determined crab recruitment patterns. Our results suggest that the nursery value of different habitats is highly dependent on the dispersal potential (primary and secondary dispersal) to and from these areas, which is largely determined by the relative position of habitats within the estuarine landscape.

Role of rasagiline in treating Parkinson’s disease: Effect on disease progression

PubMed Central

Malaty, Irene A; Fernandez, Hubert H

2009-01-01

Rasagiline is a second generation, selective, irreversible monoamine oxidase type B (MAO-B) inhibitor. It has demonstrated efficacy in monotherapy for early Parkinson’s disease (PD) patients in one large randomized, placebo-controlled trial (TVP-1012 in Early Monotherapy for Parkinson’s Disease Outpatients), and has shown ability to reduce off time in more advanced PD patients with motor fluctuations in two large placebo-controlled trials (Parkinson’s Rasagiline: Efficacy and Safety in the Treatment of “Off”, and Lasting Effect in Adjunct Therapy With Rasagiline Given Once Daily). Preclinical data abound to suggest potential for neuroprotection by this compound against a variety of neurotoxic insults in cell cultures and in animals. The lack of amphetamine metabolites provides an advantage over the first generation MAO-B inhibitor selegiline. One large trial has investigated the potential for disease modification in PD patients (Attenuation of Disease progression with Azilect Given Once-daily) and preliminary results maintain some possible advantage to earlier initiation of the 1 mg/day dose. The clinical significance of the difference detected remains a consideration. PMID:19753135

Integration of fringe projection and two-dimensional digital image correlation for three-dimensional displacements measurements

NASA Astrophysics Data System (ADS)

Felipe-Sesé, Luis; López-Alba, Elías; Siegmann, Philip; Díaz, Francisco A.

2016-12-01

A low-cost approach for three-dimensional (3-D) full-field displacement measurement is applied for the analysis of large displacements involved in two different mechanical events. The method is based on a combination of fringe projection and two-dimensional digital image correlation (DIC) techniques. The two techniques have been employed simultaneously using an RGB camera and a color encoding method; therefore, it is possible to measure in-plane and out-of-plane displacements at the same time with only one camera even at high speed rates. The potential of the proposed methodology has been employed for the analysis of large displacements during contact experiments in a soft material block. Displacement results have been successfully compared with those obtained using a 3D-DIC commercial system. Moreover, the analysis of displacements during an impact test on a metal plate was performed to emphasize the application of the methodology for dynamics events. Results show a good level of agreement, highlighting the potential of FP + 2D DIC as low-cost alternative for the analysis of large deformations problems.

Validation of a triangular quantum well model for GaN-based HEMTs used in pH and dipole moment sensing

NASA Astrophysics Data System (ADS)

Rabbaa, S.; Stiens, J.

2012-11-01

Gallium nitride (GaN) is a relatively new semiconductor material that has the potential of replacing gallium arsenide (GaAs) in some of the more recent technological applications, for example chemical sensor applications. In this paper, we introduce a triangular quantum well model for an undoped AlGaN/GaN high electron mobility transistor (HEMT) structure used as a chemical and biological sensor for pH and dipole moment measurements of polar liquids. We have performed theoretical calculations related to the HEMT characteristics and we have compared them with experimental measurements carried out in many previous papers. These calculations include the current-voltage (I-V) characteristics of the device, the surface potential, the change in the drain current with the dipole moment and the drain current as a function of pH. The results exhibit good agreement with experimental measurements for different polar liquids and electrolyte solutions. It is also found that the drain current of the device exhibits a large linear variation with the dipole moment, and that the surface potential and the drain current depend strongly on the pH. Therefore, it can distinguish molecules with slightly different dipole moments and solutions with small variations in pH. The ability of the device to sense biomolecules (such as proteins) with very large dipole moments is investigated.

Free Global Dsm Assessment on Large Scale Areas Exploiting the Potentialities of the Innovative Google Earth Engine Platform

NASA Astrophysics Data System (ADS)

Nascetti, A.; Di Rita, M.; Ravanelli, R.; Amicuzi, M.; Esposito, S.; Crespi, M.

2017-05-01

The high-performance cloud-computing platform Google Earth Engine has been developed for global-scale analysis based on the Earth observation data. In particular, in this work, the geometric accuracy of the two most used nearly-global free DSMs (SRTM and ASTER) has been evaluated on the territories of four American States (Colorado, Michigan, Nevada, Utah) and one Italian Region (Trentino Alto- Adige, Northern Italy) exploiting the potentiality of this platform. These are large areas characterized by different terrain morphology, land covers and slopes. The assessment has been performed using two different reference DSMs: the USGS National Elevation Dataset (NED) and a LiDAR acquisition. The DSMs accuracy has been evaluated through computation of standard statistic parameters, both at global scale (considering the whole State/Region) and in function of the terrain morphology using several slope classes. The geometric accuracy in terms of Standard deviation and NMAD, for SRTM range from 2-3 meters in the first slope class to about 45 meters in the last one, whereas for ASTER, the values range from 5-6 to 30 meters. In general, the performed analysis shows a better accuracy for the SRTM in the flat areas whereas the ASTER GDEM is more reliable in the steep areas, where the slopes increase. These preliminary results highlight the GEE potentialities to perform DSM assessment on a global scale.

Bias present in US federal agency power plant CO2 emissions data and implications for the US clean power plan

NASA Astrophysics Data System (ADS)

Gurney, K. R.; Huang, J.; Coltin, K.

2016-06-01

Power plants constitute roughly 40% of carbon dioxide (CO2) emissions in the United States. Climate change science, air pollution regulation, and potential carbon trading policies rely on accurate, unbiased quantification of these large point sources. Two US federal agencies—the Department of Energy and the Environmental Protection Agency—tabulate the emissions from US power plants using two different methodological approaches. We have analyzed those two data sets and have found that when averaged over all US facilities, the median percentage difference is less than 3%. However, this small difference masks large, non-Gaussian, positive and negative differences at individual facilities. For example, over the 2001-2009 time period, nearly one-half of the facilities have monthly emission differences that exceed roughly ±6% and one-fifth exceed roughly ±13%. It is currently not possible to assess whether one, or both, of the datasets examined here are responsible for the emissions difference. Differences this large at the individual facility level raise concerns regarding the operationalization of policy within the United States such as the recently announced Clean Power Plan. This policy relies on the achievement of state-level CO2 emission rate targets. When examined at the state-level we find that one-third of the states have differences that exceed 10% of their assigned reduction amount. Such levels of uncertainty raise concerns about the ability of individual states to accurately quantify emission rates in order to meet the regulatory targets.

Biomimetic Beetle-Inspired Flapping Air Vehicle Actuated by Ionic Polymer-Metal Composite Actuator

PubMed Central

Zhao, Yang; Xu, Di; Sheng, Jiazheng; Meng, Qinglong; Wu, Dezhi; Wang, Lingyun; Xiao, Jingjing; Lv, Wenlong; Sun, Daoheng

2018-01-01

During the last decades, the ionic polymer-metal composite (IPMC) received much attention because of its potential capabilities, such as large displacement and flexible bending actuation. In this paper, a biomimetic flapping air vehicle was proposed by combining the superiority of ionic polymer metal composite with the bionic beetle flapping principle. The blocking force was compared between casted IPMC and IPMC. The flapping state of the wing was investigated and the maximum displacement and flapping angle were measured. The flapping displacement under different voltage and frequency was tested. The flapping displacement of the wing and the support reaction force were measured under different frequency by experiments. The experimental results indicate that the high voltage and low frequency would get large flapping displacement. PMID:29682006

A robust and effective time-independent route to the calculation of Resonance Raman spectra of large molecules in condensed phases with the inclusion of Duschinsky, Herzberg-Teller, anharmonic, and environmental effects

PubMed Central

Egidi, Franco; Bloino, Julien; Cappelli, Chiara; Barone, Vincenzo

2015-01-01

We present an effective time-independent implementation to model vibrational resonance Raman (RR) spectra of medium-large molecular systems with the inclusion of Franck-Condon (FC) and Herzberg-Teller (HT) effects and a full account of the possible differences between the harmonic potential energy surfaces of the ground and resonant electronic states. Thanks to a number of algorithmic improvements and very effective parallelization, the full computations of fundamentals, overtones, and combination bands can be routinely performed for large systems possibly involving more than two electronic states. In order to improve the accuracy of the results, an effective inclusion of the leading anharmonic effects is also possible, together with environmental contributions under different solvation regimes. Reduced-dimensionality approaches can further enlarge the range of applications of this new tool. Applications to imidazole, pyrene, and chlorophyll a1 in solution are reported, as well as comparisons with available experimental data. PMID:26550003

Finding common ground in large carnivore conservation: mapping contending perspectives

USGS Publications Warehouse

Mattson, D.J.; Byrd, K.L.; Rutherford, M.B.; Brown, S.R.; Clark, T.W.

2006-01-01

Reducing current conflict over large carnivore conservation and designing effective strategies that enjoy broad public support depend on a better understanding of the values, beliefs, and demands of those who are involved or affected. We conducted a workshop attended by diverse participants involved in conservation of large carnivores in the northern U.S. Rocky Mountains, and used Q methodology to elucidate participant perspectives regarding "problems" and "solutions". Q methodology employs qualitative and quantitative techniques to reveal the subjectivity in any situation. We identified four general perspectives for both problems and solutions, three of which (Carnivore Advocates, Devolution Advocates, and Process Reformers) were shared by participants across domains. Agency Empathizers (problems) and Economic Pragmatists (solutions) were not clearly linked. Carnivore and Devolution Advocates expressed diametrically opposed perspectives that legitimized different sources of policy-relevant information ("science" for Carnivore Advocates and "local knowledge" for Devolution Advocates). Despite differences, we identified potential common ground focused on respectful, persuasive, and creative processes that would build understanding and tolerance. ?? 2006 Elsevier Ltd. All rights reserved.

Analysis on the University’s Network Security Level System in the Big Data Era

NASA Astrophysics Data System (ADS)

Li, Tianli

2017-12-01

The rapid development of science and technology, the continuous expansion of the scope of computer network applications, has gradually improved the social productive forces, has had a positive impact on the increase production efficiency and industrial scale of China's different industries. Combined with the actual application of computer network in the era of large data, we can see the existence of influencing factors such as network virus, hacker and other attack modes, threatening network security and posing a potential threat to the safe use of computer network in colleges and universities. In view of this unfavorable development situation, universities need to pay attention to the analysis of the situation of large data age, combined with the requirements of network security use, to build a reliable network space security system from the equipment, systems, data and other different levels. To avoid the security risks exist in the network. Based on this, this paper will analyze the hierarchical security system of cyberspace security in the era of large data.

A constructive model potential method for atomic interactions

NASA Technical Reports Server (NTRS)

Bottcher, C.; Dalgarno, A.

1974-01-01

A model potential method is presented that can be applied to many electron single centre and two centre systems. The development leads to a Hamiltonian with terms arising from core polarization that depend parametrically upon the positions of the valence electrons. Some of the terms have been introduced empirically in previous studies. Their significance is clarified by an analysis of a similar model in classical electrostatics. The explicit forms of the expectation values of operators at large separations of two atoms given by the model potential method are shown to be equivalent to the exact forms when the assumption is made that the energy level differences of one atom are negligible compared to those of the other.

Weak Lensing Results of the Merging Cluster A1758

NASA Technical Reports Server (NTRS)

Markevitch, M.; Gonzalez, A. H.; Bradac, M.

2011-01-01

Here we present the weak lensing results of A1758, which is known to have four cluster members undergoing two separate mergers, A1758N and A1758S. Weak lensing results of A1758N agree with previous weak lensing results of clusters lE0657-558 (Bullet cluster) and MACS J0025.4-1222, whose X-ray gas components were found to be largely separated from their clusters' gravitational potentials. A1758N has a geometry that is different from previously published mergers in that one of its X-ray peaks overlays the corresponding gravitational potential and the other X-ray peak is well separated from its cluster's gravitational potential.

Potential distribution dataset of honeybees in Indian Ocean Islands: Case study of Zanzibar Island.

PubMed

Mwalusepo, Sizah; Muli, Eliud; Nkoba, Kiatoko; Nguku, Everlyn; Kilonzo, Joseph; Abdel-Rahman, Elfatih M; Landmann, Tobias; Fakih, Asha; Raina, Suresh

2017-10-01

Honeybees ( Apis mellifera ) are principal insect pollinators, whose worldwide distribution and abundance is known to largely depend on climatic conditions. However, the presence records dataset on potential distribution of honeybees in Indian Ocean Islands remain less documented. Presence records in shape format and probability of occurrence of honeybees with different temperature change scenarios is provided in this article across Zanzibar Island. Maximum entropy (Maxent) package was used to analyse the potential distribution of honeybees. The dataset provides information on the current and future distribution of the honey bees in Zanzibar Island. The dataset is of great importance for improving stakeholders understanding of the role of temperature change on the spatial distribution of honeybees.

Outlook and Challenges of Perovskite Solar Cells toward Terawatt-Scale Photovoltaic Module Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Kai; Kim, Donghoe; Whitaker, James B

Rapid development of perovskite solar cells (PSCs) during the past several years has made this photovoltaic (PV) technology a serious contender for potential large-scale deployment on the terawatt scale in the PV market. To successfully transition PSC technology from the laboratory to industry scale, substantial efforts need to focus on scalable fabrication of high-performance perovskite modules with minimum negative environmental impact. Here, we provide an overview of the current research and our perspective regarding PSC technology toward future large-scale manufacturing and deployment. Several key challenges discussed are (1) a scalable process for large-area perovskite module fabrication; (2) less hazardous chemicalmore » routes for PSC fabrication; and (3) suitable perovskite module designs for different applications.« less

An overview of the domestication and impact of the Salmonella mobilome.

PubMed

Mebrhatu, Mehari Tesfazgi; Cenens, William; Aertsen, Abram

2014-02-01

Salmonella spp. are accountable for a large fraction of the global infectious disease burden, with most of their infections being food- or water-borne. The phenotypic features and adaptive potential of Salmonella spp. appear to be driven to a large extent by mobile or laterally acquired genetic elements. A better understanding of the conduct and diversification of these important pathogens consequently requires a more profound insight into the different mechanisms by which these pivotal elements establish themselves in the cell and affect its behavior. This review, therefore, provides an overview of the physiological impact and domestication of the Salmonella mobilome.

A Mixed Finite Volume Element Method for Flow Calculations in Porous Media

NASA Technical Reports Server (NTRS)

Jones, Jim E.

1996-01-01

A key ingredient in the simulation of flow in porous media is the accurate determination of the velocities that drive the flow. The large scale irregularities of the geology, such as faults, fractures, and layers suggest the use of irregular grids in the simulation. Work has been done in applying the finite volume element (FVE) methodology as developed by McCormick in conjunction with mixed methods which were developed by Raviart and Thomas. The resulting mixed finite volume element discretization scheme has the potential to generate more accurate solutions than standard approaches. The focus of this paper is on a multilevel algorithm for solving the discrete mixed FVE equations. The algorithm uses a standard cell centered finite difference scheme as the 'coarse' level and the more accurate mixed FVE scheme as the 'fine' level. The algorithm appears to have potential as a fast solver for large size simulations of flow in porous media.

Biennial Wind Energy Conference and Workshop, 5th, Washington, DC, October 5-7, 1981, Proceedings

NASA Astrophysics Data System (ADS)

1982-05-01

The results of studies funded by the Federal government to advance the state of the art of wind energy conversion systems (WECS) construction, operation, applications, and financial viability are presented. The economics of WECS were considered in terms of applicable tax laws, computer simulations of net value of WECS to utilities, and the installation of Mod-2 2.5 MW and WTS-4 4MW wind turbines near Medicine Bow, WY to test the operation of two different large WECS on the same utility grid. Potential problems of increasing penetration of WECS-produced electricity on a utility grid were explored and remedies suggested. The structural dynamics of wind turbines were analyzed, along with means to predict potential noise pollution from large WECS, and to make blade fatigue life assessments. Finally, Darrieus rotor aerodynamics were investigated, as were dynamic stall in small WECS and lightning protection for wind turbines and components.

Large-Scale Brain Simulation and Disorders of Consciousness. Mapping Technical and Conceptual Issues.

PubMed

Farisco, Michele; Kotaleski, Jeanette H; Evers, Kathinka

2018-01-01

Modeling and simulations have gained a leading position in contemporary attempts to describe, explain, and quantitatively predict the human brain's operations. Computer models are highly sophisticated tools developed to achieve an integrated knowledge of the brain with the aim of overcoming the actual fragmentation resulting from different neuroscientific approaches. In this paper we investigate the plausibility of simulation technologies for emulation of consciousness and the potential clinical impact of large-scale brain simulation on the assessment and care of disorders of consciousness (DOCs), e.g., Coma, Vegetative State/Unresponsive Wakefulness Syndrome, Minimally Conscious State. Notwithstanding their technical limitations, we suggest that simulation technologies may offer new solutions to old practical problems, particularly in clinical contexts. We take DOCs as an illustrative case, arguing that the simulation of neural correlates of consciousness is potentially useful for improving treatments of patients with DOCs.

Large-Scale Brain Simulation and Disorders of Consciousness. Mapping Technical and Conceptual Issues

PubMed Central

Farisco, Michele; Kotaleski, Jeanette H.; Evers, Kathinka

2018-01-01

Modeling and simulations have gained a leading position in contemporary attempts to describe, explain, and quantitatively predict the human brain’s operations. Computer models are highly sophisticated tools developed to achieve an integrated knowledge of the brain with the aim of overcoming the actual fragmentation resulting from different neuroscientific approaches. In this paper we investigate the plausibility of simulation technologies for emulation of consciousness and the potential clinical impact of large-scale brain simulation on the assessment and care of disorders of consciousness (DOCs), e.g., Coma, Vegetative State/Unresponsive Wakefulness Syndrome, Minimally Conscious State. Notwithstanding their technical limitations, we suggest that simulation technologies may offer new solutions to old practical problems, particularly in clinical contexts. We take DOCs as an illustrative case, arguing that the simulation of neural correlates of consciousness is potentially useful for improving treatments of patients with DOCs. PMID:29740372

Lower Stratospheric Temperature Differences Between Meteorological Analyses in two cold Arctic Winters and their Impact on Polar Processing Studies

NASA Technical Reports Server (NTRS)

Manney, Gloria L.; Sabutis, Joseph L.; Pawson, Steven; Santee, Michelle L.; Naujokat, Barbara; Swinbank, Richard; Gelman, Melvyn E.; Ebisuzaki, Wesley; Atlas, Robert (Technical Monitor)

2001-01-01

A quantitative intercomparison of six meteorological analyses is presented for the cold 1999-2000 and 1995-1996 Arctic winters. The impacts of using different analyzed temperatures in calculations of polar stratospheric cloud (PSC) formation potential, and of different winds in idealized trajectory-based temperature histories, are substantial. The area with temperatures below a PSC formation threshold commonly varies by approximately 25% among the analyses, with differences of over 50% at some times/locations. Freie University at Berlin analyses are often colder than others at T is less than or approximately 205 K. Biases between analyses vary from year to year; in January 2000. U.K. Met Office analyses were coldest and National Centers for Environmental Prediction (NCEP) analyses warmest. while NCEP analyses were usually coldest in 1995-1996 and Met Office or NCEP[National Center for Atmospheric Research Reanalysis (REAN) warmest. European Centre for Medium Range Weather Forecasting (ECMWF) temperatures agreed better with other analyses in 1999-2000, after improvements in the assimilation model. than in 1995-1996. Case-studies of temperature histories show substantial differences using Met Office, NCEP, REAN and NASA Data Assimilation Office (DAO) analyses. In January 2000 (when a large cold region was centered in the polar vortex), qualitatively similar results were obtained for all analyses. However, in February 2000 (a much warmer period) and in January and February 1996 (comparably cold to January 2000 but with large cold regions near the polar vortex edge), distributions of "potential PSC lifetimes" and total time spent below a PSC formation threshold varied significantly among the analyses. Largest peaks in "PSC lifetime" distributions in January 2000 were at 4-6 and 11-14 days. while in the 1996 periods, they were at 1-3 days. Thus different meteorological conditions in comparably cold winters had a large impact on expectations for PSC formation and on the discrepancies between different meteorological analyses. Met Office. NCEP, REAN, ECMWF and DAO analyses are commonly used for trajectory calculations and in chemical transport models; the choice of which analysis to use can strongly influence the results of such studies.

Wildfire risk assessment in a typical Mediterranean wildland-urban interface of Greece.

PubMed

Mitsopoulos, Ioannis; Mallinis, Giorgos; Arianoutsou, Margarita

2015-04-01

The purpose of this study was to assess spatial wildfire risk in a typical Mediterranean wildland-urban interface (WUI) in Greece and the potential effect of three different burning condition scenarios on the following four major wildfire risk components: burn probability, conditional flame length, fire size, and source-sink ratio. We applied the Minimum Travel Time fire simulation algorithm using the FlamMap and ArcFuels tools to characterize the potential response of the wildfire risk to a range of different burning scenarios. We created site-specific fuel models of the study area by measuring the field fuel parameters in representative natural fuel complexes, and we determined the spatial extent of the different fuel types and residential structures in the study area using photointerpretation procedures of large scale natural color orthophotographs. The results included simulated spatially explicit fire risk components along with wildfire risk exposure analysis and the expected net value change. Statistical significance differences in simulation outputs between the scenarios were obtained using Tukey's significance test. The results of this study provide valuable information for decision support systems for short-term predictions of wildfire risk potential and inform wildland fire management of typical WUI areas in Greece.

Wildfire Risk Assessment in a Typical Mediterranean Wildland-Urban Interface of Greece

NASA Astrophysics Data System (ADS)

Mitsopoulos, Ioannis; Mallinis, Giorgos; Arianoutsou, Margarita

2015-04-01

The purpose of this study was to assess spatial wildfire risk in a typical Mediterranean wildland-urban interface (WUI) in Greece and the potential effect of three different burning condition scenarios on the following four major wildfire risk components: burn probability, conditional flame length, fire size, and source-sink ratio. We applied the Minimum Travel Time fire simulation algorithm using the FlamMap and ArcFuels tools to characterize the potential response of the wildfire risk to a range of different burning scenarios. We created site-specific fuel models of the study area by measuring the field fuel parameters in representative natural fuel complexes, and we determined the spatial extent of the different fuel types and residential structures in the study area using photointerpretation procedures of large scale natural color orthophotographs. The results included simulated spatially explicit fire risk components along with wildfire risk exposure analysis and the expected net value change. Statistical significance differences in simulation outputs between the scenarios were obtained using Tukey's significance test. The results of this study provide valuable information for decision support systems for short-term predictions of wildfire risk potential and inform wildland fire management of typical WUI areas in Greece.

Genetic and molecular bases of yield-associated traits: a translational biology approach between rice and wheat.

PubMed

Valluru, Ravi; Reynolds, Matthew P; Salse, Jerome

2014-07-01

Transferring the knowledge bases between related species may assist in enlarging the yield potential of crop plants. Being cereals, rice and wheat share a high level of gene conservation; however, they differ at metabolic levels as a part of the environmental adaptation resulting in different yield capacities. This review focuses on the current understanding of genetic and molecular regulation of yield-associated traits in both crop species, highlights the similarities and differences and presents the putative knowledge gaps. We focus on the traits associated with phenology, photosynthesis, and assimilate partitioning and lodging resistance; the most important drivers of yield potential. Currently, there are large knowledge gaps in the genetic and molecular control of such major biological processes that can be filled in a translational biology approach in transferring genomics and genetics informations between rice and wheat.

Heat-flow properties of systems with alternate masses or alternate on-site potentials.

PubMed

Pereira, Emmanuel; Santana, Leonardo M; Ávila, Ricardo

2011-07-01

We address a central issue of phononics: the search of properties or mechanisms to manage the heat flow in reliable materials. We analytically study standard and simple systems modeling the heat flow in solids, namely, the harmonic, self-consistent harmonic and also anharmonic chains of oscillators, and we show an interesting insulating effect: While in the homogeneous models the heat flow decays as the inverse of the particle mass, in the chain with alternate masses it decays as the inverse of the square of the mass difference, that is, it decays essentially as the mass ratio (between the smaller and the larger one) for a large mass difference. A similar effect holds if we alternate on-site potentials instead of particle masses. The existence of such behavior in these different systems, including anharmonic models, indicates that it is a ubiquitous phenomenon with applications in the heat flow control.

Modeling of equilibrium hollow objects stabilized by electrostatics.

PubMed

Mani, Ethayaraja; Groenewold, Jan; Kegel, Willem K

2011-05-18

The equilibrium size of two largely different kinds of hollow objects behave qualitatively differently with respect to certain experimental conditions. Yet, we show that they can be described within the same theoretical framework. The objects we consider are 'minivesicles' of ionic and nonionic surfactant mixtures, and shells of Keplerate-type polyoxometalates. The finite-size of the objects in both systems is manifested by electrostatic interactions. We emphasize the importance of constant charge and constant potential boundary conditions. Taking these conditions into account, indeed, leads to the experimentally observed qualitatively different behavior of the equilibrium size of the objects.

Energy Partition and Variability of Earthquakes

NASA Astrophysics Data System (ADS)

Kanamori, H.

2003-12-01

During an earthquake the potential energy (strain energy + gravitational energy + rotational energy) is released, and the released potential energy (Δ W) is partitioned into radiated energy (ER), fracture energy (EG), and thermal energy (E H). How Δ W is partitioned into these energies controls the behavior of an earthquake. The merit of the slip-weakening concept is that only ER and EG control the dynamics, and EH can be treated separately to discuss the thermal characteristics of an earthquake. In general, if EG/E_R is small, the event is ``brittle", if EG /ER is large, the event is ``quasi static" or, in more common terms, ``slow earthquakes" or ``creep". If EH is very large, the event may well be called a thermal runaway rather than an earthquake. The difference in energy partition has important implications for the rupture initiation, evolution and excitation of long-period ground motions from very large earthquakes. We review the current state of knowledge on this problem in light of seismological observations and the basic physics of fracture. With seismological methods, we can measure only ER and the lower-bound of Δ W, Δ W0, and estimation of other energies involves many assumptions. ER: Although ER can be directly measured from the radiated waves, its determination is difficult because a large fraction of energy radiated at the source is attenuated during propagation. With the commonly used teleseismic and regional methods, only for events with MW>7 and MW>4, respectively, we can directly measure more than 10% of the total radiated energy. The rest must be estimated after correction for attenuation. Thus, large uncertainties are involved, especially for small earthquakes. Δ W0: To estimate Δ W0, estimation of the source dimension is required. Again, only for large earthquakes, the source dimension can be estimated reliably. With the source dimension, the static stress drop, Δ σ S, and Δ W0, can be estimated. EG: Seismologically, EG is the energy mechanically dissipated during faulting. In the context of the slip-weakening model, EG can be estimated from Δ W0 and ER. Alternatively, EG can be estimated from the laboratory data on the surface energy, the grain size and the total volume of newly formed fault gouge. This method suggests that, for crustal earthquakes, EG/E_R is very small, less than 0.2 even for extreme cases, for earthquakes with MW>7. This is consistent with the EG estimated with seismological methods, and the fast rupture speeds during most large earthquakes. For shallow subduction-zone earthquakes, EG/E_R varies substantially depending on the tectonic environments. EH: Direct estimation of EH is difficult. However, even with modest friction, EH can be very large, enough to melt or even dissociate a significant amount of material near the slip zone for large events with large slip, and the associated thermal effects may have significant effects on fault dynamics. The energy partition varies significantly for different types of earthquakes, e.g. large earthquakes on mature faults, large earthquakes on faults with low slip rates, subduction-zone earthquakes, deep focus earthquakes etc; this variability manifests itself in the difference in the evolution of seismic slip pattern. The different behaviors will be illustrated using the examples for large earthquakes, including, the 2001 Kunlun, the 1998 Balleny Is., the 1994 Bolivia, the 2001 India earthquake, the 1999 Chi-Chi, and the 2002 Denali earthquakes.

Nonhost Resistance of Barley to Different Fungal Pathogens Is Associated with Largely Distinct, Quantitative Transcriptional Responses1[W][OA

PubMed Central

Zellerhoff, Nina; Himmelbach, Axel; Dong, Wubei; Bieri, Stephane; Schaffrath, Ulrich; Schweizer, Patrick

2010-01-01

Nonhost resistance protects plants against attack by the vast majority of potential pathogens, including phytopathogenic fungi. Despite its high biological importance, the molecular architecture of nonhost resistance has remained largely unexplored. Here, we describe the transcriptional responses of one particular genotype of barley (Hordeum vulgare subsp. vulgare ‘Ingrid’) to three different pairs of adapted (host) and nonadapted (nonhost) isolates of fungal pathogens, which belong to the genera Blumeria (powdery mildew), Puccinia (rust), and Magnaporthe (blast). Nonhost resistance against each of these pathogens was associated with changes in transcript abundance of distinct sets of nonhost-specific genes, although general (not nonhost-associated) transcriptional responses to the different pathogens overlapped considerably. The powdery mildew- and blast-induced differences in transcript abundance between host and nonhost interactions were significantly correlated with differences between a near-isogenic pair of barley lines that carry either the Mlo wild-type allele or the mutated mlo5 allele, which mediates basal resistance to powdery mildew. Moreover, during the interactions of barley with the different host or nonhost pathogens, similar patterns of overrepresented and underrepresented functional categories of genes were found. The results suggest that nonhost resistance and basal host defense of barley are functionally related and that nonhost resistance to different fungal pathogens is associated with more robust regulation of complex but largely nonoverlapping sets of pathogen-responsive genes involved in similar metabolic or signaling pathways. PMID:20172964

Robustness of inflation to inhomogeneous initial conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clough, Katy; Lim, Eugene A.; DiNunno, Brandon S.

We consider the effects of inhomogeneous initial conditions in both the scalar field profile and the extrinsic curvature on different inflationary models. In particular, we compare the robustness of small field inflation to that of large field inflation, using numerical simulations with Einstein gravity in 3+1 dimensions. We find that small field inflation can fail in the presence of subdominant gradient energies, suggesting that it is much less robust to inhomogeneities than large field inflation, which withstands dominant gradient energies. However, we also show that small field inflation can be successful even if some regions of spacetime start out inmore » the region of the potential that does not support inflation. In the large field case, we confirm previous results that inflation is robust if the inflaton occupies the inflationary part of the potential. Furthermore, we show that increasing initial scalar gradients will not form sufficiently massive inflation-ending black holes if the initial hypersurface is approximately flat. Finally, we consider the large field case with a varying extrinsic curvature K , such that some regions are initially collapsing. We find that this may again lead to local black holes, but overall the spacetime remains inflationary if the spacetime is open, which confirms previous theoretical studies.« less

Refining the Use of the Web (and Web Search) as a Language Teaching and Learning Resource

ERIC Educational Resources Information Center

Wu, Shaoqun; Franken, Margaret; Witten, Ian H.

2009-01-01

The web is a potentially useful corpus for language study because it provides examples of language that are contextualized and authentic, and is large and easily searchable. However, web contents are heterogeneous in the extreme, uncontrolled and hence "dirty," and exhibit features different from the written and spoken texts in other linguistic…

Stem Cell, Regenerative Medicine and Cancer | Center for Cancer Research

Cancer.gov

Of the estimated trillion cells that build up our bodies, only a little number can self-renew and give rise to many different cell types. These unspecialized cells are called stem cells. Stem cell division and differentiation is fundamental to the development of the mature organism. Stem cells have recently attracted significant attention largely due to their potential medical

Large divalent cations and electrostatic potentials adjacent to membranes. Experimental results with hexamethonium.

PubMed Central

Alvarez, O; Brodwick, M; Latorre, R; McLaughlin, A; McLaughlin, S; Szabo, G

1983-01-01

A simple extension of the Gouy-Chapman theory predicts that the ability of a divalent cation to screen charges at a membrane-solution interface decreases significantly if the distance between the charges on the cation is comparable with the Debye length. We tested this prediction by investigating the effect of hexamethonium on the electrostatic potential adjacent to negatively charged phospholipid bilayer membranes. The distance between the two charges of an extended hexamethonium molecule is approximately 1 nm, which is the Debye length in the 0.1 M monovalent salt solutions used in these experiments. Six different experimental approaches were utilized. We measured the electrophoretic mobility of multilamellar vesicles to determine the zeta potential, the line width of the 31P nuclear magnetic resonance (NMR) signal from sonicated vesicles to calculate the change in potential at the phosphodiester moiety of the lipid, and the conductance of planar bilayer membranes exposed to either carriers (nonactin) or pore formers (gramicidin) to estimate the change in potential within the membrane. We also measured directly the effect of hexamethonium on the potential above a monolayer formed from negative lipids, and attempted to calculate the change in the surface potential of a bilayer membrane from capacitance measurements. With the exception of the capacitance calculations, each of the techniques gave comparable results: hexamethonium exerts a smaller effect on the potential than that predicted by the classic screening theory. The results are consistent with the predictions of the extended Gouy-Chapman theory and are relevant to the interpretation of physiological and pharmacological experiments that utilize hexamethonium and other large divalent cations. PMID:6198001

Vacuum selection on axionic landscapes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Gaoyuan; Battefeld, Thorsten, E-mail: gaoyuan.wang@stud.uni-goettingen.de, E-mail: tbattefe@astro.physik.uni-goettingen.de

2016-04-01

We compute the distribution of minima that are reached dynamically on multi-field axionic landscapes, both numerically and analytically. Such landscapes are well suited for inflationary model building due to the presence of shift symmetries and possible alignment effects (the KNP mechanism). The resulting distribution of dynamically reached minima differs considerably from the naive expectation based on counting all vacua. These differences are more pronounced in the presence of many fields due to dynamical selection effects: while low lying minima are preferred as fields roll down the potential, trajectories are also more likely to get trapped by one of the manymore » nearby minima. We show that common analytic arguments based on random matrix theory in the large D-limit to estimate the distribution of minima are insufficient for quantitative arguments pertaining to the dynamically reached ones. This discrepancy is not restricted to axionic potentials. We provide an empirical expression for the expectation value of such dynamically reached minimas' height and argue that the cosmological constant problem is not alleviated in the absence of anthropic arguments. We further comment on the likelihood of inflation on axionic landscapes in the large D-limit.« less

Improving consistency in large laboratory courses: a design for a standardized practical exam.

PubMed

Chen, Xinnian; Graesser, Donnasue; Sah, Megha

2015-06-01

Laboratory courses serve as important gateways to science, technology, engineering, and mathematics education. One of the challenges in assessing laboratory learning is to conduct meaningful and standardized practical exams, especially for large multisection laboratory courses. Laboratory practical exams in life sciences courses are frequently administered by asking students to move from station to station to answer questions, apply knowledge gained during laboratory experiments, interpret data, and identify various tissues and organs using various microscopic and gross specimens. This approach puts a stringent time limit on all questions regardless of the level of difficulty and also invariably increases the potential risk of cheating. To avoid potential cheating in laboratory courses with multiple sections, the setup for practical exams is often changed in some way between sections. In laboratory courses with multiple instructors or teaching assistants, practical exams may be handled inconsistently among different laboratory sections, due to differences in background knowledge, perceptions of the laboratory goals, or prior teaching experience. In this article, we describe a design for a laboratory practical exam that aims to align the assessment questions with well-defined laboratory learning objectives and improve the consistency among all laboratory sections. Copyright © 2015 The American Physiological Society.

Host specificity in vascular epiphytes: a review of methodology, empirical evidence and potential mechanisms

PubMed Central

Wagner, Katrin; Mendieta-Leiva, Glenda; Zotz, Gerhard

2015-01-01

Information on the degree of host specificity is fundamental for an understanding of the ecology of structurally dependent plants such as vascular epiphytes. Starting with the seminal paper of A.F.W. Schimper on epiphyte ecology in the late 19th century over 200 publications have dealt with the issue of host specificity in vascular epiphytes. We review and critically discuss this extensive literature. The available evidence indicates that host ranges of vascular epiphytes are largely unrestricted while a certain host bias is ubiquitous. However, tree size and age and spatial autocorrelation of tree and epiphyte species have not been adequately considered in most statistical analyses. More refined null expectations and adequate replication are needed to allow more rigorous conclusions. Host specificity could be caused by a large number of tree traits (e.g. bark characteristics and architectural traits), which influence epiphyte performance. After reviewing the empirical evidence for their relevance, we conclude that future research should use a more comprehensive approach by determining the relative importance of various potential mechanisms acting locally and by testing several proposed hypotheses regarding the relative strength of host specificity in different habitats and among different groups of structurally dependent flora. PMID:25564514

A Review on Potential of Proteins as an Excipient for Developing a Nano-Carrier Delivery System.

PubMed

Chakraborty, Amrita; Dhar, Pubali

2017-01-01

In neo-age research, nano-materials have emerged as potential tools for the revolution of diagnostic and therapeutic field because of their nano-scale effects, increased surface area-volume ratio, and other beneficial properties. For the last few decades, protein has been regarded as the most attractive and versatile natural bio-macromolecule among all of the available biopolymers. Protein is largely exploited as a nano-carrier system in the pharmaceutical industry due to its low cytotoxocity, biocompatibility, biodegradability, abundant renewable sources, significant attaching ability, clinically useful targeting, and site-specific efficient uptake. This review mainly emphasizes on the latest development and progress achieved in the utilization of protein as a nano-vehicle for a large number of therapeutics such as drugs, genes, hormones, enzymse, nutraceuticals, antibodies, peptides, etc. We also discuss the sources of protein materials, fabrication aspects, advantages, constraints, in vivo and in vitro studies and provide a comparative analysis between the different types of proteins as nano-carriers. The variation of the release pattern and molecular mechanism of the encapsulated molecule with respect to different protein types and various nano-structures are also highlighted here to explore the enormous promises of this novel approach.

Prediction of large negative shaded-side spacecraft potentials

NASA Technical Reports Server (NTRS)

Prokopenko, S. M. L.; Laframboise, J. G.

1977-01-01

A calculation by Knott, for the floating potential of a spherically symmetric synchronous-altitude satellite in eclipse, was adapted to provide simple calculations of upper bounds on negative potentials which may be achieved by electrically isolated shaded surfaces on spacecraft in sunlight. Large (approximately 60 percent) increases in predicted negative shaded-side potentials are obtained. To investigate effective potential barrier or angular momentum selection effects due to the presence of less negative sunlit-side or adjacent surface potentials, these expressions were replaced by the ion random current, which is a lower bound for convex surfaces when such effects become very severe. Further large increases in predicted negative potentials were obtained, amounting to a doubling in some cases.

Combining points and lines in rectifying satellite images

NASA Astrophysics Data System (ADS)

Elaksher, Ahmed F.

2017-09-01

The quick advance in remote sensing technologies established the potential to gather accurate and reliable information about the Earth surface using high resolution satellite images. Remote sensing satellite images of less than one-meter pixel size are currently used in large-scale mapping. Rigorous photogrammetric equations are usually used to describe the relationship between the image coordinates and ground coordinates. These equations require the knowledge of the exterior and interior orientation parameters of the image that might not be available. On the other hand, the parallel projection transformation could be used to represent the mathematical relationship between the image-space and objectspace coordinate systems and provides the required accuracy for large-scale mapping using fewer ground control features. This article investigates the differences between point-based and line-based parallel projection transformation models in rectifying satellite images with different resolutions. The point-based parallel projection transformation model and its extended form are presented and the corresponding line-based forms are developed. Results showed that the RMS computed using the point- or line-based transformation models are equivalent and satisfy the requirement for large-scale mapping. The differences between the transformation parameters computed using the point- and line-based transformation models are insignificant. The results showed high correlation between the differences in the ground elevation and the RMS.

A Comparative Study of Four Methods for the Detection of Nematode Eggs and Large Protozoan Cysts in Mandrill Faecal Material.

PubMed

Pouillevet, Hanae; Dibakou, Serge-Ely; Ngoubangoye, Barthélémy; Poirotte, Clémence; Charpentier, Marie J E

2017-01-01

Coproscopical methods like sedimentation and flotation techniques are widely used in the field for studying simian gastrointestinal parasites. Four parasites of known zoonotic potential were studied in a free-ranging, non-provisioned population of mandrills (Mandrillus sphinx): 2 nematodes (Necatoramericanus/Oesophagostomum sp. complex and Strongyloides sp.) and 2 protozoan species (Balantidium coli and Entamoeba coli). Different coproscopical techniques are available but they are rarely compared to evaluate their efficiency to retrieve parasites. In this study 4 different field-friendly methods were compared. A sedimentation method and 3 different McMaster methods (using sugar, salt, and zinc sulphate solutions) were performed on 47 faecal samples collected from different individuals of both sexes and all ages. First, we show that McMaster flotation methods are appropriate to detect and thus quantify large protozoan cysts. Second, zinc sulphate McMaster flotation allows the retrieval of a higher number of parasite taxa compared to the other 3 methods. This method further shows the highest probability to detect each of the studied parasite taxa. Altogether our results show that zinc sulphate McMaster flotation appears to be the best technique to use when studying nematodes and large protozoa. © 2017 S. Karger AG, Basel.

Item Analyses of Memory Differences

PubMed Central

Salthouse, Timothy A.

2017-01-01

Objective Although performance on memory and other cognitive tests is usually assessed with a score aggregated across multiple items, potentially valuable information is also available at the level of individual items. Method The current study illustrates how analyses of variance with item as one of the factors, and memorability analyses in which item accuracy in one group is plotted as a function of item accuracy in another group, can provide a more detailed characterization of the nature of group differences in memory. Data are reported for two memory tasks, word recall and story memory, across age, ability, repetition, delay, and longitudinal contrasts. Results The item-level analyses revealed evidence for largely uniform differences across items in the age, ability, and longitudinal contrasts, but differential patterns across items in the repetition contrast, and unsystematic item relations in the delay contrast. Conclusion Analyses at the level of individual items have the potential to indicate the manner by which group differences in the aggregate test score are achieved. PMID:27618285

Bacterial Translocation Ratchets: Shared Physical Principles with Different Molecular Implementations: How bacterial secretion systems bias Brownian motion for efficient translocation of macromolecules.

PubMed

Hepp, Christof; Maier, Berenike

2017-10-01

Secretion systems enable bacteria to import and secrete large macromolecules including DNA and proteins. While most components of these systems have been identified, the molecular mechanisms of macromolecular transport remain poorly understood. Recent findings suggest that various bacterial secretion systems make use of the translocation ratchet mechanism for transporting polymers across the cell envelope. Translocation ratchets are powered by chemical potential differences generated by concentration gradients of ions or molecules that are specific to the respective secretion systems. Bacteria employ these potential differences for biasing Brownian motion of the macromolecules within the conduits of the secretion systems. Candidates for this mechanism include DNA import by the type II secretion/type IV pilus system, DNA export by the type IV secretion system, and protein export by the type I secretion system. Here, we propose that these three secretion systems employ different molecular implementations of the translocation ratchet mechanism. © 2017 The Authors. BioEssays Published by WILEY Periodicals, Inc.

Coordinating DNA polymerase traffic during high and low fidelity synthesis.

PubMed

Sutton, Mark D

2010-05-01

With the discovery that organisms possess multiple DNA polymerases (Pols) displaying different fidelities, processivities, and activities came the realization that mechanisms must exist to manage the actions of these diverse enzymes to prevent gratuitous mutations. Although many of the Pols encoded by most organisms are largely accurate, and participate in DNA replication and DNA repair, a sizeable fraction display a reduced fidelity, and act to catalyze potentially error-prone translesion DNA synthesis (TLS) past lesions that persist in the DNA. Striking the proper balance between use of these different enzymes during DNA replication, DNA repair, and TLS is essential for ensuring accurate duplication of the cell's genome. This review highlights mechanisms that organisms utilize to manage the actions of their different Pols. A particular emphasis is placed on discussion of current models for how different Pols switch places with each other at the replication fork during high fidelity replication and potentially error-pone TLS. Copyright (c) 2010 Elsevier B.V. All rights reserved.

A comparison of dispersing media for various engineered carbon nanoparticles.

PubMed

Buford, Mary C; Hamilton, Raymond F; Holian, Andrij

2007-07-27

With the increased manufacture and use of carbon nanoparticles (CNP) there has been increasing concern about the potential toxicity of fugitive CNP in the workplace and ambient environment. To address this matter a number of investigators have conducted in vitro and in vivo toxicity assessments. However, a variety of different approaches for suspension of these particles (culture media, Tween 80, dimethyl sulfoxide, phosphate-buffered saline, fetal calf serum, and others), and different sources of materials have generated potentially conflicting outcomes. The quality of the dispersion of nanoparticles is very dependent on the medium used to suspend them, and this then will most likely affect the biological outcomes. In this work, the distributions of different CNP (sources and types) have been characterized in various media. Furthermore, the outcome of instilling the different agglomerates, or size distributions, was examined in mouse lungs after one and seven days. Our results demonstrated that CNP suspended in serum produced particle suspensions with the fewest large agglomerates, and the most uniform distribution in mouse lungs. In addition, no apparent clearance of instilled CNP took place from lungs even after seven days. This work demonstrates that CNP agglomerates are present in all dispersing vehicles to some degree. The vehicle that contains some protein, lipid or protein/lipid component disperses the CNP best, producing fewer large CNP agglomerates. In contrast, vehicles absent of lipid and protein produce the largest CNP agglomerates. The source of the CNP is also a factor in the degree of particle agglomeration within the same vehicle.

Population structure of resident, immigrant, and swimming Corophium volutator (Amphipoda) on an intertidal mudflat in the Bay of Fundy, Canada

NASA Astrophysics Data System (ADS)

Drolet, David; Barbeau, Myriam A.

2012-05-01

Spatial variation in biotic and abiotic conditions, and differences in dispersive behavior of different life history stages can result in the formation of zones with different demography for infaunal and epifaunal species within vast intertidal flats. In this study, we evaluated within-mudflat homogeneity of the infaunal amphipod Corophium volutator found in the mud (residents), colonizing artificially disturbed areas (immigrants), and caught in the water column (swimmers) on a large mudflat in the upper Bay of Fundy, Canada. Densities of residents, immigrants, and swimmers were well structured in space (both along and across shore). Occasionally, significant differences in size structure, sex ratio, and proportion of ovigerous females were found at different intertidal levels, but these were short-lived. Comparisons of size and sex structure of residents, immigrants, and swimmers revealed occasional marked differences, with small juveniles and large adult males moving most. However, this size-bias in movement did not translate into zones with different population dynamics, suggesting that ample dispersal, through swimming and drifting in the water column, homogenized the population and masked potential effects of variation in environmental conditions. We therefore conclude that the mudflat represents one homogeneous population.

Addressing the stimulant treatment gap: A call to investigate the therapeutic benefits potential of cannabinoids for crack-cocaine use.

PubMed

Fischer, Benedikt; Kuganesan, Sharan; Gallassi, Andrea; Malcher-Lopes, Renato; van den Brink, Wim; Wood, Evan

2015-12-01

Crack-cocaine use is prevalent in numerous countries, yet concentrated primarily - largely within urban contexts - in the Northern and Southern regions of the Americas. It is associated with a variety of behavioral, physical and mental health and social problems which gravely affect users and their environments. Few evidence-based treatments for crack-cocaine use exist and are available to users in the reality of street drug use. Numerous pharmacological treatments have been investigated but with largely disappointing results. An important therapeutic potential for crack-cocaine use may rest in cannabinoids, which have recently seen a general resurgence for varied possible therapeutic usages for different neurological diseases. Distinct potential therapeutic benefits for crack-cocaine use and common related adverse symptoms may come specifically from cannabidiol (CBD) - one of the numerous cannabinoid components found in cannabis - with its demonstrated anxiolytic, anti-psychotic, anti-convulsant effects and potential benefits for sleep and appetite problems. The possible therapeutic prospects of cannabinoids are corroborated by observational studies from different contexts documenting crack-cocaine users' 'self-medication' efforts towards coping with crack-cocaine-related problems, including withdrawal and craving, impulsivity and paranoia. Cannabinoid therapeutics offer further benefits of being available in multiple formulations, are low in adverse risk potential, and may easily be offered in community-based settings which may add to their feasibility as interventions for - predominantly marginalized - crack-cocaine user populations. Supported by the dearth of current therapeutic options for crack-cocaine use, we are advocating for the implementation of a rigorous research program investigating the potential therapeutic benefits of cannabinoids for crack-cocaine use. Given the high prevalence of this grave substance use problem in the Americas, opportunities for such research should urgently be created and facilitated there. Copyright © 2015 Elsevier B.V. All rights reserved.

Statistical analysis of mesoscale rainfall: Dependence of a random cascade generator on large-scale forcing

NASA Technical Reports Server (NTRS)

Over, Thomas, M.; Gupta, Vijay K.

1994-01-01

Under the theory of independent and identically distributed random cascades, the probability distribution of the cascade generator determines the spatial and the ensemble properties of spatial rainfall. Three sets of radar-derived rainfall data in space and time are analyzed to estimate the probability distribution of the generator. A detailed comparison between instantaneous scans of spatial rainfall and simulated cascades using the scaling properties of the marginal moments is carried out. This comparison highlights important similarities and differences between the data and the random cascade theory. Differences are quantified and measured for the three datasets. Evidence is presented to show that the scaling properties of the rainfall can be captured to the first order by a random cascade with a single parameter. The dependence of this parameter on forcing by the large-scale meteorological conditions, as measured by the large-scale spatial average rain rate, is investigated for these three datasets. The data show that this dependence can be captured by a one-to-one function. Since the large-scale average rain rate can be diagnosed from the large-scale dynamics, this relationship demonstrates an important linkage between the large-scale atmospheric dynamics and the statistical cascade theory of mesoscale rainfall. Potential application of this research to parameterization of runoff from the land surface and regional flood frequency analysis is briefly discussed, and open problems for further research are presented.

Reflective properties of randomly rough surfaces under large incidence angles.

PubMed

Qiu, J; Zhang, W J; Liu, L H; Hsu, P-f; Liu, L J

2014-06-01

The reflective properties of randomly rough surfaces at large incidence angles have been reported due to their potential applications in some of the radiative heat transfer research areas. The main purpose of this work is to investigate the formation mechanism of the specular reflection peak of rough surfaces at large incidence angles. The bidirectional reflectance distribution function (BRDF) of rough aluminum surfaces with different roughnesses at different incident angles is measured by a three-axis automated scatterometer. This study used a validated and accurate computational model, the rigorous coupled-wave analysis (RCWA) method, to compare and analyze the measurement BRDF results. It is found that the RCWA results show the same trend of specular peak as the measurement. This paper mainly focuses on the relative roughness at the range of 0.16<σ/λ<5.35. As the relative roughness decreases, the specular peak enhancement dramatically increases and the scattering region significantly reduces, especially under large incidence angles. The RCWA and the Rayleigh criterion results have been compared, showing that the relative error of the total integrated scatter increases as the roughness of the surface increases at large incidence angles. In addition, the zero-order diffractive power calculated by RCWA and the reflectance calculated by Fresnel equations are compared. The comparison shows that the relative error declines sharply when the incident angle is large and the roughness is small.

Venomous snakebites in an urban area: what are the possibilities?

PubMed

Jasper, E H; Miller, M; Neuburger, K J; Widder, P C; Snyder, J W; Lopez, B L

2000-01-01

To estimate the number of different species of venomous snakes privately kept in a large urban area. An anonymous survey of potential snake owners in the Philadelphia urban and suburban area. The survey was mailed to members of the Philadelphia Herpetological Society. In addition, the survey was published in 2 herpetological newsletters and online in the Herpetology Network. One hundred sixty responses were obtained during a 6-month period. Ownership of 74 different varieties of venomous snakes was reported. Antivenin was not locally available for 13 of these species. A wide variety of venomous captive snakes can be found in the private sector. The potential for having to treat an envenomation requires the emergency physician to maintain an education of snakebite management options, including the various antivenin options available in their geographical location.

Analytical model of surface potential profiles and transfer characteristics for hetero stacked tunnel field-effect transistors

NASA Astrophysics Data System (ADS)

Xu, Hui Fang; Sun, Wen; Han, Xin Feng

2018-06-01

An analytical model of surface potential profiles and transfer characteristics for hetero stacked tunnel field-effect transistors (HS-TFETs) is presented for the first time, where hetero stacked materials are composed of two different bandgaps. The bandgap of the underlying layer is smaller than that of the upper layer. Under different device parameters (upper layer thickness, underlying layer thickness, and hetero stacked materials) and temperature, the validity of the model is demonstrated by the agreement of its results with the simulation results. Moreover, the results show that the HS-TFETs can obtain predominant performance with relatively slow changes of subthreshold swing (SS) over a wide drain current range, steep average subthreshold swing, high on-state current, and large on–off state current ratio.

Buccal swabbing as a noninvasive method to determine bacterial, archaeal, and eukaryotic microbial community structures in the rumen.

PubMed

Kittelmann, Sandra; Kirk, Michelle R; Jonker, Arjan; McCulloch, Alan; Janssen, Peter H

2015-11-01

Analysis of rumen microbial community structure based on small-subunit rRNA marker genes in metagenomic DNA samples provides important insights into the dominant taxa present in the rumen and allows assessment of community differences between individuals or in response to treatments applied to ruminants. However, natural animal-to-animal variation in rumen microbial community composition can limit the power of a study considerably, especially when only subtle differences are expected between treatment groups. Thus, trials with large numbers of animals may be necessary to overcome this variation. Because ruminants pass large amounts of rumen material to their oral cavities when they chew their cud, oral samples may contain good representations of the rumen microbiota and be useful in lieu of rumen samples to study rumen microbial communities. We compared bacterial, archaeal, and eukaryotic community structures in DNAs extracted from buccal swabs to those in DNAs from samples collected directly from the rumen by use of a stomach tube for sheep on four different diets. After bioinformatic depletion of potential oral taxa from libraries of samples collected via buccal swabs, bacterial communities showed significant clustering by diet (R = 0.37; analysis of similarity [ANOSIM]) rather than by sampling method (R = 0.07). Archaeal, ciliate protozoal, and anaerobic fungal communities also showed significant clustering by diet rather than by sampling method, even without adjustment for potentially orally associated microorganisms. These findings indicate that buccal swabs may in future allow quick and noninvasive sampling for analysis of rumen microbial communities in large numbers of ruminants. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

LiNbO3 surfaces from a microscopic perspective

NASA Astrophysics Data System (ADS)

Sanna, Simone; Gero Schmidt, Wolf

2017-10-01

A large number of oxides has been investigated in the last twenty years as possible new materials for various applications ranging from opto-electronics to heterogeneous catalysis. In this context, ferroelectric oxides are particularly promising. The electric polarization plays a crucial role at many oxide surfaces, and it largely determines their physical and chemical properties. Ferroelectrics offer in addition the possibility to control/switch the electric polarization and hence the surface chemistry, allowing for the realization of domain-engineered nanoscale devices such as molecular detectors or highly efficient catalysts. Lithium niobate (LiNbO3) is a ferroelectric with a high spontaneous polarization, whose surfaces have a huge and largely unexplored potential. Owing to recent advances in experimental techniques and sample preparation, peculiar and exclusive properties of LiNbO3 surfaces could be demonstrated. For example, water films freeze at different temperatures on differently polarized surfaces, and the chemical etching properties of surfaces with opposite polarization are strongly different. More important, the ferroelectric domain orientation affects temperature dependent surface stabilization mechanisms and molecular adsorption phenomena. Various ab initio theoretical investigations have been performed in order to understand the outcome of these experiments and the origin of the exotic behavior of the lithium niobate surfaces. Thanks to these studies, many aspects of their surface physics and chemistry could be clarified. Yet other puzzling features are still not understood. This review gives a résumé on the present knowledge of lithium niobate surfaces, with a particular view on their microscopic properties, explored in recent years by means of ab initio calculations. Relevant aspects and properties of the surfaces that need further investigation are briefly discussed. The review is concluded with an outlook of challenges and potential payoff for LiNbO3 based applications.

Estaurine Freshwater Entrainment By Oyster Reefs: Quantifying A Keystone Ecosystem Service

NASA Astrophysics Data System (ADS)

Kaplan, D. A.; Olabarrieta, M.; Frederick, P.; Valle-Levinson, A.; Seavey, J.

2014-12-01

Oyster reefs have been shown to provide myriad critical ecosystem services, however their role in directing flow and currents during non-storm conditions has been largely neglected. In many regions, oyster reefs form as linear structures perpendicular to the coast and across the path of streams and rivers, potentially entraining large volumes of freshwater flow and altering nearshore mixing. We hypothesize that these reefs have the potential to influence salinity over large areas, providing a "keystone" ecosystem service by supporting multiple estuarine functions. Here we present results from a field and modeling study to quantify the effects of reef extent and elevation on estuarine salinities under varying river discharge. We found salinity differences ranging from 2 to 16 g/kg between inshore and offshore sides of degraded oyster reefs in the Suwannee Sound (FL, USA), supporting the role of reefs as local-scale freshwater dams. Moreover, differences between inshore and offshore salinities were correlated with flow, with the most marked differences during periods of low flow. Hydrodynamic modeling using the 3-D Regional Ocean Modeling System (ROMS) suggests that the currently degraded reef system entrained greater volumes of freshwater in the past, buffering the landward advance of high salinities, particularly during low flow events related to droughts. Using ROMS, we also modeled a variety of hypothetical oyster bar morphology scenarios (historical, current, and "restored") to understand how changes in reef structure (elevation, extent, and completeness) impact estuarine mixing and near-shore salinities. Taken together, these results serve to: 1) elucidate a poorly documented ecosystem service of oyster reefs; 2) provide an estimate of the magnitude and sptial extent of the freshwater entrainment effect; and 3) offer quantitative information to managers and restoration specialists interested in restoring oyster habitat.

Deformation of periodic nanovoid structures in Mg single crystals

NASA Astrophysics Data System (ADS)

Xu, Shuozhi; Su, Yanqing; Zare Chavoshi, Saeed

2018-01-01

Large scale molecular dynamics (MD) simulations in Mg single crystal containing periodic cylindrical voids subject to uniaxial tension along the z direction are carried out. Models with different initial void sizes and crystallographic orientations are explored using two interatomic potentials. It is found that (i) a larger initial void always leads to a lower yield stress, in agreement with an analytic prediction; (ii) in the model with x[\\bar{1}100]-y[0001]-z[11\\bar{2}0] orientations, the two potentials predict different types of tension twins and phase transformation; (iii) in the model with x[0001]-y[11\\bar{2}0]-z[\\bar{1}100] orientations, the two potentials identically predict the nucleation of edge dislocations on the prismatic plane, which then glide away from the void, resulting in extrusions at the void surface; in the case of the smallest initial void, these surface extrusions pinch the void into two voids. Besides bringing new physical understanding of the nanovoid structures, our work highlights the variability and uncertainty in MD simulations arising from the interatomic potential, an issue relatively lightly addressed in the literature to date.

Impact of Groundwater Salinity on Bioremediation Enhanced by Micro-Nano Bubbles

PubMed Central

Li, Hengzhen; Hu, Liming; Xia, Zhiran

2013-01-01

Micro-nano bubbles (MNBs) technology has shown great potential in groundwater bioremediation because of their large specific surface area, negatively charged surface, long stagnation, high oxygen transfer efficiency, etc. Groundwater salinity, which varies from sites due to different geological and environmental conditions, has a strong impact on the bioremediation effect. However, the groundwater salinity effect on MNBs’ behavior has not been reported. In this study, the size distribution, oxygen transfer efficiency and zeta potential of MNBs was investigated in different salt concentrations. In addition, the permeability of MNBs’ water through sand in different salt concentrations was studied. The results showed that water salinity has no influence on bubble size distribution during MNBs generation. MNBs could greatly enhance the oxygen transfer efficiency from inner bubbles to outer water, which may greatly enhance aerobic bioremediation. However, the enhancement varied depending on salt concentration. 0.7 g/L was found to be the optimal salt concentration to transfer oxygen. Moreover, MNBs in water salinity of 0.7 g/L had the minimum zeta potential. The correlation of zeta potential and mass transfer was discussed. The hydraulic conductivities of sand were similar for MNBs water with different salt concentrations. The results suggested that salinity had a great influence on MNBs performance, and groundwater salinity should be taken into careful consideration in applying MNBs technology to the enhancement of bioremediation. PMID:28788299

Imaging the Anomalous Charge Distribution Inside CsPbBr3 Perovskite Quantum Dots Sensitized Solar Cells.

PubMed

Panigrahi, Shrabani; Jana, Santanu; Calmeiro, Tomás; Nunes, Daniela; Martins, Rodrigo; Fortunato, Elvira

2017-10-24

Highly luminescent CsPbBr 3 perovskite quantum dots (QDs) have gained huge attention in research due to their various applications in optoelectronics, including as a light absorber in photovoltaic solar cells. To improve the performances of such devices, it requires a deeper knowledge on the charge transport dynamics inside the solar cell, which are related to its power-conversion efficiency. Here, we report the successful fabrication of an all-inorganic CsPbBr 3 perovskite QD sensitized solar cell and the imaging of anomalous electrical potential distribution across the layers of the cell under different illuminations using Kelvin probe force microscopy. Carrier generation, separation, and transport capacity inside the cells are dependent on the light illumination. Large differences in surface potential between electron and hole transport layers with unbalanced carrier separation at the junction have been observed under white light (full solar spectrum) illumination. However, under monochromatic light (single wavelength of solar spectrum) illumination, poor charge transport occurred across the junction as a consequence of less difference in surface potential between the active layers. The outcome of this study provides a clear idea on the carrier dynamic processes inside the cells and corresponding surface potential across the layers under the illumination of different wavelengths of light to understand the functioning of the solar cells and ultimately for the improvement of their photovoltaic performances.

Fabrication of large binary colloidal crystals with a NaCl structure

PubMed Central

Vermolen, E. C. M.; Kuijk, A.; Filion, L. C.; Hermes, M.; Thijssen, J. H. J.; Dijkstra, M.; van Blaaderen, A.

2009-01-01

Binary colloidal crystals offer great potential for tuning material properties for applications in, for example, photonics, semiconductors and spintronics, because they allow the positioning of particles with quite different characteristics on one lattice. For micrometer-sized colloids, it is believed that gravity and slow crystallization rates hinder the formation of high-quality binary crystals. Here, we present methods for growing binary colloidal crystals with a NaCl structure from relatively heavy, hard-sphere-like, micrometer-sized silica particles by exploring the following external fields: electric, gravitational, and dielectrophoretic fields and a structured surface (colloidal epitaxy). Our simulations show that the free-energy difference between the NaCl and NiAs structures, which differ in their stacking of the hexagonal planes of the larger spheres, is very small (≈0.002 kBT). However, we demonstrate that the fcc stacking of the large spheres, which is crucial for obtaining the pure NaCl structure, can be favored by using a combination of the above-mentioned external fields. In this way, we have successfully fabricated large, 3D, oriented single crystals having a NaCl structure without stacking disorder. PMID:19805259

Efficient molecular dynamics simulations with many-body potentials on graphics processing units

NASA Astrophysics Data System (ADS)

Fan, Zheyong; Chen, Wei; Vierimaa, Ville; Harju, Ari

2017-09-01

Graphics processing units have been extensively used to accelerate classical molecular dynamics simulations. However, there is much less progress on the acceleration of force evaluations for many-body potentials compared to pairwise ones. In the conventional force evaluation algorithm for many-body potentials, the force, virial stress, and heat current for a given atom are accumulated within different loops, which could result in write conflict between different threads in a CUDA kernel. In this work, we provide a new force evaluation algorithm, which is based on an explicit pairwise force expression for many-body potentials derived recently (Fan et al., 2015). In our algorithm, the force, virial stress, and heat current for a given atom can be accumulated within a single thread and is free of write conflicts. We discuss the formulations and algorithms and evaluate their performance. A new open-source code, GPUMD, is developed based on the proposed formulations. For the Tersoff many-body potential, the double precision performance of GPUMD using a Tesla K40 card is equivalent to that of the LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) molecular dynamics code running with about 100 CPU cores (Intel Xeon CPU X5670 @ 2.93 GHz).

Large-scale electrophysiology: acquisition, compression, encryption, and storage of big data.

PubMed

Brinkmann, Benjamin H; Bower, Mark R; Stengel, Keith A; Worrell, Gregory A; Stead, Matt

2009-05-30

The use of large-scale electrophysiology to obtain high spatiotemporal resolution brain recordings (>100 channels) capable of probing the range of neural activity from local field potential oscillations to single-neuron action potentials presents new challenges for data acquisition, storage, and analysis. Our group is currently performing continuous, long-term electrophysiological recordings in human subjects undergoing evaluation for epilepsy surgery using hybrid intracranial electrodes composed of up to 320 micro- and clinical macroelectrode arrays. DC-capable amplifiers, sampling at 32kHz per channel with 18-bits of A/D resolution are capable of resolving extracellular voltages spanning single-neuron action potentials, high frequency oscillations, and high amplitude ultra-slow activity, but this approach generates 3 terabytes of data per day (at 4 bytes per sample) using current data formats. Data compression can provide several practical benefits, but only if data can be compressed and appended to files in real-time in a format that allows random access to data segments of varying size. Here we describe a state-of-the-art, scalable, electrophysiology platform designed for acquisition, compression, encryption, and storage of large-scale data. Data are stored in a file format that incorporates lossless data compression using range-encoded differences, a 32-bit cyclically redundant checksum to ensure data integrity, and 128-bit encryption for protection of patient information.

Potential toxicological hazard due to endocrine-disrupting chemicals on Mediterranean top predators: State of art, gender differences and methodological tools

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fossi, M.C.; Casini, S.; Marsili, L.

Man-made endocrine-disrupting chemicals (EDCs) range across all continents and oceans. Some geographic areas are potentially more threatened than others: one of these is the Mediterranean Sea. Levels of some xenobiotics are much higher here than in other seas and oceans. In this paper we review the final results of a project supported by the Italian Ministry of the Environment, in which the hypothesis that Mediterranean top predator species (such as large pelagic fish and marine mammals) are potentially at risk due to EDCs was investigated. We illustrate the need to develop and apply sensitive methodological tools, such as biomarkers (Vitellogenin,more » Zona Radiata proteins and CYP1A activities) for evaluation of toxicological risk in large pelagic fish top predators (Swordfish (Xiphias gladius), Bluefin Tuna (Thunnus thynnus thynnus)) and nondestructive biomarkers (CYP1A activities and fibroblast cell culture in skin biopsy), for the hazard assessment of threatened marine mammals species (Striped Dolphin, (Stenella coeruleoalba), Bottlenose Dolphin (Tursiops truncatus), Common Dolphin (Delphinus delphis) and Fin Whale (Balaenoptera physalus))exposed to EDCs. Differential gender susceptibility to EDCs is also explored both in large pelagic fish and in cetaceans. In cetaceans, male specimens showed higher cytochrome P450 induction (BPMO in skyn biopsies, CYP2B in fibroblasts cell cultures) by xenobiotics with respect to females.« less

Large-scale Electrophysiology: Acquisition, Compression, Encryption, and Storage of Big Data

PubMed Central

Brinkmann, Benjamin H.; Bower, Mark R.; Stengel, Keith A.; Worrell, Gregory A.; Stead, Matt

2009-01-01

The use of large-scale electrophysiology to obtain high spatiotemporal resolution brain recordings (>100 channels) capable of probing the range of neural activity from local field potential oscillations to single neuron action potentials presents new challenges for data acquisition, storage, and analysis. Our group is currently performing continuous, long-term electrophysiological recordings in human subjects undergoing evaluation for epilepsy surgery using hybrid intracranial electrodes composed of up to 320 micro- and clinical macroelectrode arrays. DC-capable amplifiers, sampling at 32 kHz per channel with 18-bits of A/D resolution are capable of resolving extracellular voltages spanning single neuron action potentials, high frequency oscillations, and high amplitude ultraslow activity, but this approach generates 3 terabytes of data per day (at 4 bytes per sample) using current data formats. Data compression can provide several practical benefits, but only if data can be compressed and appended to files in real-time in a format that allows random access to data segments of varying size. Here we describe a state-of-the-art, scalable, electrophysiology platform designed for acquisition, compression, encryption, and storage of large-scale data. Data are stored in a file format that incorporates lossless data compression using range encoded differences, a 32-bit cyclically redundant checksum to ensure data integrity, and 128-bit encryption for protection of patient information. PMID:19427545

Novel Stimulation Paradigms with Temporally-Varying Parameters to Reduce Synchronous Activity at the Onset of High Frequency Stimulation in Rat Hippocampus

PubMed Central

Cai, Ziyan; Feng, Zhouyan; Guo, Zheshan; Zhou, Wenjie; Wang, Zhaoxiang; Wei, Xuefeng

2017-01-01

Deep brain stimulation (DBS) has shown wide applications for treating various disorders in the central nervous system by using high frequency stimulation (HFS) sequences of electrical pulses. However, upon the onset of HFS sequences, the narrow pulses could induce synchronous firing of action potentials among large populations of neurons and cause a transient phase of “onset response” that is different from the subsequent steady state. To investigate the transient onset phase, the antidromically-evoked population spikes (APS) were used as an electrophysiological marker to evaluate the synchronous neuronal reactions to axonal HFS in the hippocampal CA1 region of anesthetized rats. New stimulation paradigms with time-varying intensity and frequency were developed to suppress the “onset responses”. Results show that HFS paradigms with ramp-up intensity at the onset phase could suppress large APS potentials. In addition, an intensity ramp with a slower ramp-up rate or with a higher pulse frequency had greater suppression on APS amplitudes. Therefore, to reach a desired pulse intensity rapidly, a stimulation paradigm combining elevated frequency and ramp-up intensity was used to shorten the transition phase of initial HFS without evoking large APS potentials. The results of the study provide important clues for certain transient side effects of DBS and for development of new adaptive stimulation paradigms. PMID:29066946

Reproductive Biology and Its Impact on Body Size: Comparative Analysis of Mammalian, Avian and Dinosaurian Reproduction

PubMed Central

Werner, Jan; Griebeler, Eva Maria

2011-01-01

Janis and Carrano (1992) suggested that large dinosaurs might have faced a lower risk of extinction under ecological changes than similar-sized mammals because large dinosaurs had a higher potential reproductive output than similar-sized mammals (JC hypothesis). First, we tested the assumption underlying the JC hypothesis. We therefore analysed the potential reproductive output (reflected in clutch/litter size and annual offspring number) of extant terrestrial mammals and birds (as “dinosaur analogs”) and of extinct dinosaurs. With the exception of rodents, the differences in the reproductive output of similar-sized birds and mammals proposed by Janis and Carrano (1992) existed even at the level of single orders. Fossil dinosaur clutches were larger than litters of similar-sized mammals, and dinosaur clutch sizes were comparable to those of similar-sized birds. Because the extinction risk of extant species often correlates with a low reproductive output, the latter difference suggests a lower risk of population extinction in dinosaurs than in mammals. Second, we present a very simple, mathematical model that demonstrates the advantage of a high reproductive output underlying the JC hypothesis. It predicts that a species with a high reproductive output that usually faces very high juvenile mortalities will benefit more strongly in terms of population size from reduced juvenile mortalities (e.g., resulting from a stochastic reduction in population size) than a species with a low reproductive output that usually comprises low juvenile mortalities. Based on our results, we suggest that reproductive strategy could have contributed to the evolution of the exceptional gigantism seen in dinosaurs that does not exist in extant terrestrial mammals. Large dinosaurs, e.g., the sauropods, may have easily sustained populations of very large-bodied species over evolutionary time. PMID:22194835

Citizen Astronomy in China: An Overview

NASA Astrophysics Data System (ADS)

Ye, Quan-Zhi

2018-01-01

Citizen astronomers have benefited from technological advancements in the recent decades as they fill the scientific gaps left by professional astronomers, in the areas such as time domain observations, visual classification and data mining. Here I present an overview of the current status of citizen astronomy in China. Chinese citizen astronomers have made a visible contribution in the discoveries of new objects; however, comparing to their counterparts in the western world, they appear to be less interested in researches that do not involve making new discovery, such as visual classification, long-term monitoring of objects, and data mining. From a questionnaire survey that aimed to investigate the motivation of Chinese citizen astronomers, we find that this population is predominantly male (92%) who mostly reside in economically developed provinces. A large fraction (69%) of the respondents are students and young professionals younger than the age of 25, which differs significantly from the occupation and age distribution of typical Chinese Internet users as well as the user distribution of large international citizen science projects such as the Galaxy Zoo. This suggests that youth generation in China is more willing to participate citizen astronomy research than average generation. Additionally, we find that interests in astronomy, desire to learn new knowledges, have a fun experience and meet new friends in the community are all important driving factors for Chinese citizen astronomers to participate research. This also differs from their counterparts in western countries. With a large youth population that is interested in astronomy as well as a number of large astronomical facilities that are being planned or built, we believe that citizen astronomy in China has a vast potential. Timely and proper guidance from the professionals will be essential to help citizen astronomers to fulfill this potential.

Evaluation of linear classifiers on articles containing pharmacokinetic evidence of drug-drug interactions.

PubMed

Kolchinsky, A; Lourenço, A; Li, L; Rocha, L M

2013-01-01

Drug-drug interaction (DDI) is a major cause of morbidity and mortality. DDI research includes the study of different aspects of drug interactions, from in vitro pharmacology, which deals with drug interaction mechanisms, to pharmaco-epidemiology, which investigates the effects of DDI on drug efficacy and adverse drug reactions. Biomedical literature mining can aid both kinds of approaches by extracting relevant DDI signals from either the published literature or large clinical databases. However, though drug interaction is an ideal area for translational research, the inclusion of literature mining methodologies in DDI workflows is still very preliminary. One area that can benefit from literature mining is the automatic identification of a large number of potential DDIs, whose pharmacological mechanisms and clinical significance can then be studied via in vitro pharmacology and in populo pharmaco-epidemiology. We implemented a set of classifiers for identifying published articles relevant to experimental pharmacokinetic DDI evidence. These documents are important for identifying causal mechanisms behind putative drug-drug interactions, an important step in the extraction of large numbers of potential DDIs. We evaluate performance of several linear classifiers on PubMed abstracts, under different feature transformation and dimensionality reduction methods. In addition, we investigate the performance benefits of including various publicly-available named entity recognition features, as well as a set of internally-developed pharmacokinetic dictionaries. We found that several classifiers performed well in distinguishing relevant and irrelevant abstracts. We found that the combination of unigram and bigram textual features gave better performance than unigram features alone, and also that normalization transforms that adjusted for feature frequency and document length improved classification. For some classifiers, such as linear discriminant analysis (LDA), proper dimensionality reduction had a large impact on performance. Finally, the inclusion of NER features and dictionaries was found not to help classification.

Reproductive biology and its impact on body size: comparative analysis of mammalian, avian and dinosaurian reproduction.

PubMed

Werner, Jan; Griebeler, Eva Maria

2011-01-01

Janis and Carrano (1992) suggested that large dinosaurs might have faced a lower risk of extinction under ecological changes than similar-sized mammals because large dinosaurs had a higher potential reproductive output than similar-sized mammals (JC hypothesis). First, we tested the assumption underlying the JC hypothesis. We therefore analysed the potential reproductive output (reflected in clutch/litter size and annual offspring number) of extant terrestrial mammals and birds (as "dinosaur analogs") and of extinct dinosaurs. With the exception of rodents, the differences in the reproductive output of similar-sized birds and mammals proposed by Janis and Carrano (1992) existed even at the level of single orders. Fossil dinosaur clutches were larger than litters of similar-sized mammals, and dinosaur clutch sizes were comparable to those of similar-sized birds. Because the extinction risk of extant species often correlates with a low reproductive output, the latter difference suggests a lower risk of population extinction in dinosaurs than in mammals. Second, we present a very simple, mathematical model that demonstrates the advantage of a high reproductive output underlying the JC hypothesis. It predicts that a species with a high reproductive output that usually faces very high juvenile mortalities will benefit more strongly in terms of population size from reduced juvenile mortalities (e.g., resulting from a stochastic reduction in population size) than a species with a low reproductive output that usually comprises low juvenile mortalities. Based on our results, we suggest that reproductive strategy could have contributed to the evolution of the exceptional gigantism seen in dinosaurs that does not exist in extant terrestrial mammals. Large dinosaurs, e.g., the sauropods, may have easily sustained populations of very large-bodied species over evolutionary time.

A CRITICAL ASSESSMENT OF BIODOSIMETRY METHODS FOR LARGE-SCALE INCIDENTS

PubMed Central

Swartz, Harold M.; Flood, Ann Barry; Gougelet, Robert M.; Rea, Michael E.; Nicolalde, Roberto J.; Williams, Benjamin B.

2014-01-01

Recognition is growing regarding the possibility that terrorism or large-scale accidents could result in potential radiation exposure of hundreds of thousands of people and that the present guidelines for evaluation after such an event are seriously deficient. Therefore, there is a great and urgent need for after-the-fact biodosimetric methods to estimate radiation dose. To accomplish this goal, the dose estimates must be at the individual level, timely, accurate, and plausibly obtained in large-scale disasters. This paper evaluates current biodosimetry methods, focusing on their strengths and weaknesses in estimating human radiation exposure in large-scale disasters at three stages. First, the authors evaluate biodosimetry’s ability to determine which individuals did not receive a significant exposure so they can be removed from the acute response system. Second, biodosimetry’s capacity to classify those initially assessed as needing further evaluation into treatment-level categories is assessed. Third, we review biodosimetry’s ability to guide treatment, both short- and long-term, is reviewed. The authors compare biodosimetric methods that are based on physical vs. biological parameters and evaluate the features of current dosimeters (capacity, speed and ease of getting information, and accuracy) to determine which are most useful in meeting patients’ needs at each of the different stages. Results indicate that the biodosimetry methods differ in their applicability to the three different stages, and that combining physical and biological techniques may sometimes be most effective. In conclusion, biodosimetry techniques have different properties, and knowledge of their properties for meeting the different needs for different stages will result in their most effective use in a nuclear disaster mass-casualty event. PMID:20065671

Utilization of Satellite Data in Land Surface Hydrology: Sensitivity and Assimilation

NASA Technical Reports Server (NTRS)

Lakshmi, Venkataraman; Susskind, Joel

1999-01-01

This paper investigates the sensitivity of potential evapotranspiration to input meteorological variables, viz- surface air temperature and surface vapor pressure. The sensitivity studies have been carried out for a wide range of land surface variables such as wind speed, leaf area index and surface temperatures. Errors in the surface air temperature and surface vapor pressure result in errors of different signs in the computed potential evapotranspiration. This result has implications for use of estimated values from satellite data or analysis of surface air temperature and surface vapor pressure in large scale hydrological modeling. The comparison of cumulative potential evapotranspiration estimates using ground observations and satellite observations over Manhattan, Kansas for a period of several months shows very little difference between the two. The cumulative differences between the ground based and satellite based estimates of potential evapotranspiration amounted to less that 20mm over a 18 month period and a percentage difference of 15%. The use of satellite estimates of surface skin temperature in hydrological modeling to update the soil moisture using a physical adjustment concept is studied in detail including the extent of changes in soil moisture resulting from the assimilation of surface skin temperature. The soil moisture of the surface layer is adjusted by 0.9mm over a 10 day period as a result of a 3K difference between the predicted and the observed surface temperature. This is a considerable amount given the fact that the top layer can hold only 5mm of water.

Carbonate Precipitation through Microbial Activities in Natural Environment, and Their Potential in Biotechnology: A Review

PubMed Central

Zhu, Tingting; Dittrich, Maria

2016-01-01

Calcium carbonate represents a large portion of carbon reservoir and is used commercially for a variety of applications. Microbial carbonate precipitation, a by-product of microbial activities, plays an important metal coprecipitation and cementation role in natural systems. This natural process occurring in various geological settings can be mimicked and used for a number of biotechnologies, such as metal remediation, carbon sequestration, enhanced oil recovery, and construction restoration. In this study, different metabolic activities leading to calcium carbonate precipitation, their native environment, and potential applications and challenges are reviewed. PMID:26835451

EASApprox® skin-stretching system: A secure and effective method to achieve wound closure.

PubMed

Song, Mingzhi; Zhang, Zhen; Liu, Tao; Liu, Song; Li, Gang; Liu, Zhaochang; Huang, Jingyang; Chen, Song; Li, Linan; Guo, Li; Qiu, Yang; Wan, Jiajia; Liu, Yuejian; Wu, Tao; Wang, Xiaoyong; Lu, Ming; Wang, Shouyu

2017-07-01

Large skin defects are commonly observed in the clinic and have attracted much attention recently. Therefore, finding an effective solution for large skin defects is a global problem. The objective of the present study was to assess the effectiveness of the EASApprox ® skin-stretching system for closing large skin defects. Skin defects (5×5 cm) were created on the forearms of 9 Bama miniature pigs, which were randomly divided into the following three groups: Direct suture, the new EASApprox ® skin-stretching device and Kirschner wires. Microcirculation was assessed before surgery and after wound closure. Following the different treatments, the defects were sutured, and wound healing was assessed based on a clinical score. Furthermore, microscopic and ultramicroscopic structures were evaluated, including collagen, elastic fibers and the microvessel density. Significant differences in the clinical score and microvessel density were observed among the groups. Additionally, the mean length obtained for elastic fibers was larger than that obtained for the other two groups. Finally, the new EASApprox ® skin-stretching device resulted in successful wound management and with only minor side effects on skin histology and microcirculation. Therefore, this method has the potential to be used for healing large skin defects.

Cryo-FIB-SEM serial milling and block face imaging: Large volume structural analysis of biological tissues preserved close to their native state.

PubMed

Vidavsky, Netta; Akiva, Anat; Kaplan-Ashiri, Ifat; Rechav, Katya; Addadi, Lia; Weiner, Steve; Schertel, Andreas

2016-12-01

Many important biological questions can be addressed by studying in 3D large volumes of intact, cryo fixed hydrated tissues (⩾10,000μm 3 ) at high resolution (5-20nm). This can be achieved using serial FIB milling and block face surface imaging under cryo conditions. Here we demonstrate the unique potential of the cryo-FIB-SEM approach using two extensively studied model systems; sea urchin embryos and the tail fin of zebrafish larvae. We focus in particular on the environment of mineral deposition sites. The cellular organelles, including mitochondria, Golgi, ER, nuclei and nuclear pores are made visible by the image contrast created by differences in surface potential of different biochemical components. Auto segmentation and/or volume rendering of the image stacks and 3D reconstruction of the skeleton and the cellular environment, provides a detailed view of the relative distribution in space of the tissue/cellular components, and thus of their interactions. Simultaneous acquisition of secondary and back-scattered electron images adds additional information. For example, a serial view of the zebrafish tail reveals the presence of electron dense mineral particles inside mitochondrial networks extending more than 20μm in depth in the block. Large volume imaging using cryo FIB SEM, as demonstrated here, can contribute significantly to the understanding of the structures and functions of diverse biological tissues. Copyright © 2016 Elsevier Inc. All rights reserved.

Variability of North Atlantic Hurricane Frequency in a Large Ensemble of High-Resolution Climate Simulations

NASA Astrophysics Data System (ADS)

Mei, W.; Kamae, Y.; Xie, S. P.

2017-12-01

Forced and internal variability of North Atlantic hurricane frequency during 1951-2010 is studied using a large ensemble of climate simulations by a 60-km atmospheric general circulation model that is forced by observed sea surface temperatures (SSTs). The simulations well capture the interannual-to-decadal variability of hurricane frequency in best track data, and further suggest a possible underestimate of hurricane counts in the current best track data prior to 1966 when satellite measurements were unavailable. A genesis potential index (GPI) averaged over the Main Development Region (MDR) accounts for more than 80% of the forced variations in hurricane frequency, with potential intensity and vertical wind shear being the dominant factors. In line with previous studies, the difference between MDR SST and tropical mean SST is a simple but useful predictor; a one-degree increase in this SST difference produces 7.1±1.4 more hurricanes. The hurricane frequency also exhibits internal variability that is comparable in magnitude to the interannual variability. The 100-member ensemble allows us to address the following important questions: (1) Are the observations equivalent to one realization of such a large ensemble? (2) How many ensemble members are needed to reproduce the variability in observations and in the forced component of the simulations? The sources of the internal variability in hurricane frequency will be identified and discussed. The results provide an explanation for the relatively week correlation ( 0.6) between MDR GPI and hurricane frequency on interannual timescales in observations.

The new science of cognitive sex differences.

PubMed

Miller, David I; Halpern, Diane F

2014-01-01

Surprising new findings indicate that many conclusions about sex differences and similarities in cognitive abilities need to be reexamined. Cognitive sex differences are changing, decreasing for some tasks whereas remaining stable or increasing for other tasks. Some sex differences are detected in infancy, but the data are complex and depend on task characteristics. Diverse disciplines have revolutionized our understanding of why these differences exist. For instance, fraternal-twin studies align with earlier literature to help establish the role of prenatal androgens and large international datasets help explain how cultural factors such as economic prosperity and gender equity affect females and males differently. Understanding how biological and environmental factors interact could help maximize cognitive potential and address pressing societal issues. Copyright © 2013 Elsevier Ltd. All rights reserved.

Low but significant genetic differentiation underlies biologically meaningful phenotypic divergence in a large Atlantic salmon population.

PubMed

Aykanat, Tutku; Johnston, Susan E; Orell, Panu; Niemelä, Eero; Erkinaro, Jaakko; Primmer, Craig R

2015-10-01

Despite decades of research assessing the genetic structure of natural populations, the biological meaning of low yet significant genetic divergence often remains unclear due to a lack of associated phenotypic and ecological information. At the same time, structured populations with low genetic divergence and overlapping boundaries can potentially provide excellent models to study adaptation and reproductive isolation in cases where high-resolution genetic markers and relevant phenotypic and life history information are available. Here, we combined single nucleotide polymorphism (SNP)-based population inference with extensive phenotypic and life history data to identify potential biological mechanisms driving fine-scale subpopulation differentiation in Atlantic salmon (Salmo salar) from the Teno River, a major salmon river in Europe. Two sympatrically occurring subpopulations had low but significant genetic differentiation (FST  = 0.018) and displayed marked differences in the distribution of life history strategies, including variation in juvenile growth rate, age at maturity and size within age classes. Large, late-maturing individuals were virtually absent from one of the two subpopulations, and there were significant differences in juvenile growth rates and size at age after oceanic migration between individuals in the respective subpopulations. Our findings suggest that different evolutionary processes affect each subpopulation and that hybridization and subsequent selection may maintain low genetic differentiation without hindering adaptive divergence. © 2015 John Wiley & Sons Ltd.

Motor potential profile and a robust method for extracting it from time series of motor positions.

PubMed

Wang, Hongyun

2006-10-21

Molecular motors are small, and, as a result, motor operation is dominated by high-viscous friction and large thermal fluctuations from the surrounding fluid environment. The small size has hindered, in many ways, the studies of physical mechanisms of molecular motors. For a macroscopic motor, it is possible to observe/record experimentally the internal operation details of the motor. This is not yet possible for molecular motors. The chemical reaction in a molecular motor has many occupancy states, each having a different effect on the motor motion. The overall effect of the chemical reaction on the motor motion can be characterized by the motor potential profile. The potential profile reveals how the motor force changes with position in a motor step, which may lead to insights into how the chemical reaction is coupled to force generation. In this article, we propose a mathematical formulation and a robust method for constructing motor potential profiles from time series of motor positions measured in single molecule experiments. Numerical examples based on simulated data are shown to demonstrate the method. Interestingly, it is the small size of molecular motors (negligible inertia) that makes it possible to recover the potential profile from time series of motor positions. For a macroscopic motor, the variation of driving force within a cycle is smoothed out by the large inertia.

Taking OSCE examiner training on the road: reaching the masses

PubMed Central

Reid, Katharine; Smallwood, David; Collins, Margo; Sutherland, Ruth; Dodds, Agnes

2016-01-01

Background To ensure the rigour of objective structured clinical examinations (OSCEs) in assessing medical students, medical school educators must educate examiners with a view to standardising examiner assessment behaviour. Delivering OSCE examiner training is a necessary yet challenging part of the OSCE process. A novel approach to implementing training for current and potential OSCE examiners was trialled by delivering large-group education sessions at major teaching hospitals. Methods The ‘OSCE Roadshow’ comprised a short training session delivered in the context of teaching hospital ‘Grand Rounds’ to current and potential OSCE examiners. The training was developed to educate clinicians about OSCE processes, clarify the examiners’ role and required behaviours, and to review marking guides and mark allocation in an effort to standardise OSCE processes and encourage consistency in examiner marking behaviour. A short exercise allowed participants to practise marking a mock OSCE to investigate examiner marking behaviour after the training. Results OSCE Roadshows at four metropolitan and one rural teaching hospital were well received and well attended by 171 clinicians across six sessions. Unexpectedly, medical students also attended in large numbers (n=220). After training, participants’ average scores for the mock OSCE clustered closely around the ideal score of 28 (out of 40), and the average scores did not differ according to the levels of clinical experience. Conclusion The OSCE Roadshow demonstrated the potential of brief familiarisation training in reaching large numbers of current and potential OSCE examiners in a time and cost-effective manner to promote standardisation of OSCE processes. PMID:27687287

Profiling of potential driver mutations in sarcomas by targeted next generation sequencing.

PubMed

Andersson, Carola; Fagman, Henrik; Hansson, Magnus; Enlund, Fredrik

2016-04-01

Comprehensive genetic profiling by massively parallel sequencing, commonly known as next generation sequencing (NGS), is becoming the foundation of personalized oncology. For sarcomas very few targeted treatments are currently in routine use. In clinical practice the preoperative diagnostic workup of soft tissue tumours largely relies on core needle biopsies. Although mostly sufficient for histopathological diagnosis, only very limited amounts of formalin fixated paraffin embedded tissue are often available for predictive mutation analysis. Targeted NGS may thus open up new possibilities for comprehensive characterization of scarce biopsies. We therefore set out to search for driver mutations by NGS in a cohort of 55 clinically and morphologically well characterized sarcomas using low input of DNA from formalin fixated paraffin embedded tissues. The aim was to investigate if there are any recurrent or targetable aberrations in cancer driver genes in addition to known chromosome translocations in different types of sarcomas. We employed a panel covering 207 mutation hotspots in 50 cancer-associated genes to analyse DNA from nine gastrointestinal stromal tumours, 14 synovial sarcomas, seven myxoid liposarcomas, 22 Ewing sarcomas and three Ewing-like small round cell tumours at a large sequencing depth to detect also mutations that are subclonal or occur at low allele frequencies. We found nine mutations in eight different potential driver genes, some of which are potentially actionable by currently existing targeted therapies. Even though no recurrent mutations in driver genes were found in the different sarcoma groups, we show that targeted NGS-based sequencing is clearly feasible in a diagnostic setting with very limited amounts of paraffin embedded tissue and may provide novel insights into mesenchymal cell signalling and potentially druggable targets. Interestingly, we also identify five non-synonymous sequence variants in 4 established cancer driver genes in DNA from normal tissue from sarcoma patients that may possibly predispose or contribute to neoplastic development. Copyright © 2016 Elsevier Inc. All rights reserved.

Internal architecture, permeability structure, and hydrologic significance of contrasting fault-zone types

NASA Astrophysics Data System (ADS)

Rawling, Geoffrey C.; Goodwin, Laurel B.; Wilson, John L.

2001-01-01

The Sand Hill fault is a steeply dipping, large-displacement normal fault that cuts poorly lithified Tertiary sediments of the Albuquerque basin, New Mexico, United States. The fault zone does not contain macroscopic fractures; the basic structural element is the deformation band. The fault core is composed of foliated clay flanked by structurally and lithologically heterogeneous mixed zones, in turn flanked by damage zones. Structures present within these fault-zone architectural elements are different from those in brittle faults formed in lithified sedimentary and crystalline rocks that do contain fractures. These differences are reflected in the permeability structure of the Sand Hill fault. Equivalent permeability calculations indicate that large-displacement faults in poorly lithified sediments have little potential to act as vertical-flow conduits and have a much greater effect on horizontal flow than faults with fractures.

Profiling of lipid and glycogen accumulations under different growth conditions in the sulfothermophilic red alga Galdieria sulphuraria.

PubMed

Sakurai, Toshihiro; Aoki, Motohide; Ju, Xiaohui; Ueda, Tatsuya; Nakamura, Yasunori; Fujiwara, Shoko; Umemura, Tomonari; Tsuzuki, Mikio; Minoda, Ayumi

2016-01-01

The unicellular red alga Galdieria sulphuraria grows efficiently and produces a large amount of biomass in acidic conditions at high temperatures. It has great potential to produce biofuels and other beneficial compounds without becoming contaminated with other organisms. In G. sulphuraria, biomass measurements and glycogen and lipid analyses demonstrated that the amounts and compositions of glycogen and lipids differed when cells were grown under autotrophic, mixotrophic, and heterotrophic conditions. Maximum biomass production was obtained in the mixotrophic culture. High amounts of glycogen were obtained in the mixotrophic cultures, while the amounts of neutral lipids were similar between mixotrophic and heterotrophic cultures. The amounts of neutral lipids were highest in red algae, including thermophiles. Glycogen structure and fatty acids compositions largely depended on the growth conditions. Copyright © 2015. Published by Elsevier Ltd.

Somatic spikes regulate dendritic signaling in small neurons in the absence of backpropagating action potentials.

PubMed

Myoga, Michael H; Beierlein, Michael; Regehr, Wade G

2009-06-17

Somatic spiking is known to regulate dendritic signaling and associative synaptic plasticity in many types of large neurons, but it is unclear whether somatic action potentials play similar roles in small neurons. Here we ask whether somatic action potentials can also influence dendritic signaling in an electrically compact neuron, the cerebellar stellate cell (SC). Experiments were conducted in rat brain slices using a combination of imaging and electrophysiology. We find that somatic action potentials elevate dendritic calcium levels in SCs. There was little attenuation of calcium signals with distance from the soma in SCs from postnatal day 17 (P17)-P19 rats, which had dendrites that averaged 60 microm in length, and in short SC dendrites from P30-P33 rats. Somatic action potentials evoke dendritic calcium increases that are not affected by blocking dendritic sodium channels. This indicates that dendritic signals in SCs do not rely on dendritic sodium channels, which differs from many types of large neurons, in which dendritic sodium channels and backpropagating action potentials allow somatic spikes to control dendritic calcium signaling. Despite the lack of active backpropagating action potentials, we find that trains of somatic action potentials elevate dendritic calcium sufficiently to release endocannabinoids and retrogradely suppress parallel fiber to SC synapses in P17-P19 rats. Prolonged SC firing at physiologically realistic frequencies produces retrograde suppression when combined with low-level group I metabotropic glutamate receptor activation. Somatic spiking also interacts with synaptic stimulation to promote associative plasticity. These findings indicate that in small neurons the passive spread of potential within dendrites can allow somatic spiking to regulate dendritic calcium signaling and synaptic plasticity.

Use of morphometric soil aggregates parameters to evaluate the reclamation process in mined areas located at amazon forest - Brazil

NASA Astrophysics Data System (ADS)

Ribeiro, A. I.; Fengler, F. H.; Longo, R. M.; Mello, G. F.; Damame, D. B.; Crowley, D. E.

2015-12-01

Brazil has a high mineral potential that have been explored over the years. A large fraction of these mineral resources are located in Amazon region, which is known for its large biodiversity and world climate importance. As the policies that control the Amazon preservation are relatively new, several mining activities have been exploring the Amazon territory, promoting a large process of degradation. Once the mining activities have a high potential of environmental changes the government created polices to restrain the mining in Amazon forests and obligate mining companies to reclaim theirs minded areas. However, the measurement of reclamation development still is a challenging task for the Professionals involved. The volume and complexity of the variables, allied to the difficulty in identifying the reclamation of ecosystem functionalities are still lack to ensure the reclamation success. In this sense this work aims to investigate the representativeness of morphometric soil aggregates parameters in the understanding of reclamation development. The study area is located in the National Forest of Jamari, State of Rondônia. In the past mining companies explored the region producing eight closed mines that are now in reclamation process. The soil aggregates morphometric measurements: geometric mean diameter (GMD), aggregate circularity index, and aggregate roundness, were choose based in its obtaining facility, and their association to biological activity. To achieve the proposed objective the aggregates of eight sites in reclamation, from different closed mines, where chosen and compared to Amazon forest and open mine soil aggregates. The results were analyzed to one way ANOVA to identifying differences between areas in reclamation, natural ecosystem, and open mine. It was obtained differences for GMD and circularity index. However, only the circularity index allowed to identifying differences between the reclamation sites. The results allowed concluding: (1) Morphometric aggregates measurements can represent the reclamation process in Amazon territory; (2) To validate the results more areas in reclamation process in different ecosystems must be investigated; (3) Roundness didn't represented any differences.Key words: circularity index, ecosystem, geometric mean diameter.

Evolution of the properties of Al(n)N(n) clusters with size.

PubMed

Costales, Aurora; Blanco, M A; Francisco, E; Pandey, Ravindra; Martín Pendás, A

2005-12-29

A global optimization of stoichiometric (AlN)(n) clusters (n = 1-25, 30, 35, ..., 95, 100) has been performed using the basin-hopping (BH) method and describing the interactions with simple and yet realistic interatomic potentials. The results for the smaller isomers agree with those of previous electronic structure calculations, thus validating the present scheme. The lowest-energy isomers found can be classified in three different categories according to their structural motifs: (i) small clusters (n = 2-5), with planar ring structures and 2-fold coordination, (ii) medium clusters (n = 6-40), where a competition between stacked rings and globular-like empty cages exists, and (iii) large clusters (n > 40), large enough to mix different elements of the previous stage. All the atoms in small and medium-sized clusters are in the surface, while large clusters start to display interior atoms. Large clusters display a competition between tetrahedral and octahedral-like features: the former lead to a lower energy interior in the cluster, while the latter allow for surface terminations with a lower energy. All of the properties studied present different regimes according to the above classification. It is of particular interest that the local properties of the interior atoms do converge to the bulk limit. The isomers with n = 6 and 12 are specially stable with respect to the gain or loss of AlN molecules.

The ESO Diffuse Interstellar Band Large Exploration Survey (EDIBLES)

NASA Astrophysics Data System (ADS)

Cami, J.; Cox, N. L.; Farhang, A.; Smoker, J.; Elyajouri, M.; Lallement, R.; Bacalla, X.; Bhatt, N. H.; Bron, E.; Cordiner, M. A.; de Koter, A..; Ehrenfreund, P.; Evans, C.; Foing, B. H.; Javadi, A.; Joblin, C.; Kaper, L.; Khosroshahi, H. G.; Laverick, M.; Le Petit, F..; Linnartz, H.; Marshall, C. C.; Monreal-Ibero, A.; Mulas, G.; Roueff, E.; Royer, P.; Salama, F.; Sarre, P. J.; Smith, K. T.; Spaans, M.; van Loon, J. T..; Wade, G.

2018-03-01

The ESO Diffuse Interstellar Band Large Exploration Survey (EDIBLES) is a Large Programme that is collecting high-signal-to-noise (S/N) spectra with UVES of a large sample of O and B-type stars covering a large spectral range. The goal of the programme is to extract a unique sample of high-quality interstellar spectra from these data, representing different physical and chemical environments, and to characterise these environments in great detail. An important component of interstellar spectra is the diffuse interstellar bands (DIBs), a set of hundreds of unidentified interstellar absorption lines. With the detailed line-of-sight information and the high-quality spectra, EDIBLES will derive strong constraints on the potential DIB carrier molecules. EDIBLES will thus guide the laboratory experiments necessary to identify these interstellar “mystery molecules”, and turn DIBs into powerful diagnostics of their environments in our Milky Way Galaxy and beyond. We present some preliminary results showing the unique capabilities of the EDIBLES programme.

Role of Rituximab and Rituximab Biosimilars in Diffuse Large B-Cell Lymphoma.

PubMed

Coleman, Morton; Lammers, Philip E; Ciceri, Fabio; Jacobs, Ira A

2016-04-01

Diffuse large B-cell lymphoma (DLBCL), an aggressive non-Hodgkin lymphoma (NHL), is the most-common subtype of NHL. DLBCL can be classified into at least 3 major immunologically distinct types, which contributes to considerable variation in disease prognosis and response to treatment. DLBCL potentially is curable, even when diagnosed at advanced stages. The current standard of care for most patients with untreated or relapsed/refractory DLBCL is chemoimmunotherapy containing rituximab, an anti-CD20 monoclonal antibody. With advanced understanding of the molecular mechanisms involved in the pathogenesis of DLBCL and specific signaling pathways that are activated in different subtypes, potential new therapeutic targets have been identified, some of which are at the late stages of clinical development. This review summarizes the critical role of rituximab in the current standard of care treatment for DLBCL and discusses why rituximab is likely to remain an important component of treatment options for DLBCL in the foreseeable future. In addition, current and emerging therapeutic agents, including potential benefits of rituximab biosimilars, for patients with DLBCL are discussed. The advent of rituximab biosimilars may facilitate accessibility of rituximab-based chemotherapies to patients with DLBCL and has potential cost-saving benefits for healthcare systems globally. Copyright © 2016 Elsevier Inc. All rights reserved.

Biotechnological Potential of Cold Adapted Pseudoalteromonas spp. Isolated from ‘Deep Sea’ Sponges

PubMed Central

Borchert, Erik; Knobloch, Stephen; Dwyer, Emilie; Flynn, Sinéad; Jackson, Stephen A.; Jóhannsson, Ragnar; Marteinsson, Viggó T.; O’Gara, Fergal; Dobson, Alan D. W.

2017-01-01

The marine genus Pseudoalteromonas is known for its versatile biotechnological potential with respect to the production of antimicrobials and enzymes of industrial interest. We have sequenced the genomes of three Pseudoalteromonas sp. strains isolated from different deep sea sponges on the Illumina MiSeq platform. The isolates have been screened for various industrially important enzymes and comparative genomics has been applied to investigate potential relationships between the isolates and their host organisms, while comparing them to free-living Pseudoalteromonas spp. from shallow and deep sea environments. The genomes of the sponge associated Pseudoalteromonas strains contained much lower levels of potential eukaryotic-like proteins which are known to be enriched in symbiotic sponge associated microorganisms, than might be expected for true sponge symbionts. While all the Pseudoalteromonas shared a large distinct subset of genes, nonetheless the number of unique and accessory genes is quite large and defines the pan-genome as open. Enzymatic screens indicate that a vast array of enzyme activities is expressed by the isolates, including β-galactosidase, β-glucosidase, and protease activities. A β-glucosidase gene from one of the Pseudoalteromonas isolates, strain EB27 was heterologously expressed in Escherichia coli and, following biochemical characterization, the recombinant enzyme was found to be cold-adapted, thermolabile, halotolerant, and alkaline active. PMID:28629190

Effect of chloride ion concentration on the galvanic corrosion of α phase brass by eccrine sweat.

PubMed

Meekins, Andrew; Bond, John W; Chaloner, Penelope

2012-07-01

Inductively coupled plasma mass spectrometry measurement of the relative concentration of sodium, chloride, calcium, and potassium ions in eccrine sweat deposits from 40 donors revealed positive correlations between chloride and sodium (ρ = 0.684, p < 0.01) and chloride and calcium ions (ρ = 0.91, p < 0.01). Correlations between ion concentration and the corrosion of α phase brass by the donated sweat were investigated by visual grading of the degree of corrosion, by measuring the copper/zinc ratio using energy-dispersive X-ray spectroscopy, and from a measurement of the potential difference between corroded and uncorroded brass when a large potential was applied to the uncorroded brass. An increasing copper/zinc ratio (indicative of dezincification) was found to correlate positively to both chloride ion concentration and visual grading of corrosion, while visual grading gave correlations with potential difference measurements that were indicative of the preferential surface oxidation of zinc rather than copper. © 2012 American Academy of Forensic Sciences.

What are the effects of Agro-Ecological Zones and land use region boundaries on land resource projection using the Global Change Assessment Model?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Di Vittorio, Alan V.; Kyle, Page; Collins, William D.

Understanding the potential impacts of climate change is complicated by mismatched spatial representations between gridded Earth System Models (ESMs) and Integrated Assessment Models (IAMs), whose regions are typically larger and defined by geopolitical and biophysical criteria. In this study we address uncertainty stemming from the construction of land use regions in an IAM, the Global Change Assessment Model (GCAM), whose regions are currently based on historical climatic conditions (1961-1990). We re-define GCAM’s regions according to projected climatic conditions (2070-2099), and investigate how this changes model outcomes for land use, agriculture, and forestry. By 2100, we find potentially large differences inmore » projected global and regional area of biomass energy crops, fodder crops, harvested forest, and intensive pasture. These land area differences correspond with changes in agricultural commodity prices and production. These results have broader implications for understanding policy scenarios and potential impacts, and for evaluating and comparing IAM and ESM simulations.« less

Potential Energy Surface of the Chromium Dimer Re-re-revisited with Multiconfigurational Perturbation Theory.

PubMed

Vancoillie, Steven; Malmqvist, Per Åke; Veryazov, Valera

2016-04-12

The chromium dimer has long been a benchmark molecule to evaluate the performance of different computational methods ranging from density functional theory to wave function methods. Among the latter, multiconfigurational perturbation theory was shown to be able to reproduce the potential energy surface of the chromium dimer accurately. However, for modest active space sizes, it was later shown that different definitions of the zeroth-order Hamiltonian have a large impact on the results. In this work, we revisit the system for the third time with multiconfigurational perturbation theory, now in order to increase the active space of the reference wave function. This reduces the impact of the choice of zeroth-order Hamiltonian and improves the shape of the potential energy surface significantly. We conclude by comparing our results of the dissocation energy and vibrational spectrum to those obtained from several highly accurate multiconfigurational methods and experiment. For a meaningful comparison, we used the extrapolation to the complete basis set for all methods involved.

Areas prone to slow slip events impede earthquake rupture propagation and promote afterslip.

PubMed

Rolandone, Frederique; Nocquet, Jean-Mathieu; Mothes, Patricia A; Jarrin, Paul; Vallée, Martin; Cubas, Nadaya; Hernandez, Stephen; Plain, Morgan; Vaca, Sandro; Font, Yvonne

2018-01-01

At subduction zones, transient aseismic slip occurs either as afterslip following a large earthquake or as episodic slow slip events during the interseismic period. Afterslip and slow slip events are usually considered as distinct processes occurring on separate fault areas governed by different frictional properties. Continuous GPS (Global Positioning System) measurements following the 2016 M w (moment magnitude) 7.8 Ecuador earthquake reveal that large and rapid afterslip developed at discrete areas of the megathrust that had previously hosted slow slip events. Regardless of whether they were locked or not before the earthquake, these areas appear to persistently release stress by aseismic slip throughout the earthquake cycle and outline the seismic rupture, an observation potentially leading to a better anticipation of future large earthquakes.

Personality in 100,000 Words: A large-scale analysis of personality and word use among bloggers

PubMed Central

Yarkoni, Tal

2010-01-01

Previous studies have found systematic associations between personality and individual differences in word use. Such studies have typically focused on broad associations between major personality domains and aggregate word categories, potentially masking more specific associations. Here I report the results of a large-scale analysis of personality and word use in a large sample of blogs (N=694). The size of the dataset enabled pervasive correlations with personality to be identified for a broad range of lexical variables, including both aggregate word categories and individual English words. The results replicated category-level findings from previous offline studies, identified numerous novel associations at both a categorical and single-word level, and underscored the value of complementary approaches to the study of personality and word use. PMID:20563301

Mean velocity and turbulence measurements in a 90 deg curved duct with thin inlet boundary layer

NASA Technical Reports Server (NTRS)

Crawford, R. A.; Peters, C. E.; Steinhoff, J.; Hornkohl, J. O.; Nourinejad, J.; Ramachandran, K.

1985-01-01

The experimental database established by this investigation of the flow in a large rectangular turning duct is of benchmark quality. The experimental Reynolds numbers, Deans numbers and boundary layer characteristics are significantly different from previous benchmark curved-duct experimental parameters. This investigation extends the experimental database to higher Reynolds number and thinner entrance boundary layers. The 5% to 10% thick boundary layers, based on duct half-width, results in a large region of near-potential flow in the duct core surrounded by developing boundary layers with large crossflows. The turbulent entrance boundary layer case at R sub ed = 328,000 provides an incompressible flowfield which approaches real turbine blade cascade characteristics. The results of this investigation provide a challenging benchmark database for computational fluid dynamics code development.

Areas prone to slow slip events impede earthquake rupture propagation and promote afterslip

PubMed Central

Rolandone, Frederique; Nocquet, Jean-Mathieu; Mothes, Patricia A.; Jarrin, Paul; Vallée, Martin; Cubas, Nadaya; Hernandez, Stephen; Plain, Morgan; Vaca, Sandro; Font, Yvonne

2018-01-01

At subduction zones, transient aseismic slip occurs either as afterslip following a large earthquake or as episodic slow slip events during the interseismic period. Afterslip and slow slip events are usually considered as distinct processes occurring on separate fault areas governed by different frictional properties. Continuous GPS (Global Positioning System) measurements following the 2016 Mw (moment magnitude) 7.8 Ecuador earthquake reveal that large and rapid afterslip developed at discrete areas of the megathrust that had previously hosted slow slip events. Regardless of whether they were locked or not before the earthquake, these areas appear to persistently release stress by aseismic slip throughout the earthquake cycle and outline the seismic rupture, an observation potentially leading to a better anticipation of future large earthquakes. PMID:29404404

First evidence of an extensive Acheulean large cutting tool accumulation in Europe from Porto Maior (Galicia, Spain).

PubMed

Méndez-Quintas, E; Santonja, M; Pérez-González, A; Duval, M; Demuro, M; Arnold, L J

2018-02-15

We describe a European Acheulean site characterised by an extensive accumulation of large cutting tools (LCT). This type of Lower Paleolithic assemblage, with dense LCT accumulations, has only been found on the African continent and in the Near East until now. The identification of a site with large accumulations of LCTs favours the hypothesis of an African origin for the Acheulean of Southwest Europe. The lithic tool-bearing deposits date back to 293-205 thousand years ago. Our chronological findings confirm temporal overlap between sites with clear "African" Acheulean affinities and Early Middle Paleolithic sites found elsewhere in the region. These complex technological patterns could be consistent with the potential coexistence of different human species in south-western Europe during the Middle Pleistocene.

Eosinophils may play regionally disparate roles in influencing IgA(+) plasma cell numbers during large and small intestinal inflammation.

PubMed

Forman, Ruth; Bramhall, Michael; Logunova, Larisa; Svensson-Frej, Marcus; Cruickshank, Sheena M; Else, Kathryn J

2016-05-31

Eosinophils are innate immune cells present in the intestine during steady state conditions. An intestinal eosinophilia is a hallmark of many infections and an accumulation of eosinophils is also observed in the intestine during inflammatory disorders. Classically the function of eosinophils has been associated with tissue destruction, due to the release of cytotoxic granule contents. However, recent evidence has demonstrated that the eosinophil plays a more diverse role in the immune system than previously acknowledged, including shaping adaptive immune responses and providing plasma cell survival factors during the steady state. Importantly, it is known that there are regional differences in the underlying immunology of the small and large intestine, but whether there are differences in context of the intestinal eosinophil in the steady state or inflammation is not known. Our data demonstrates that there are fewer IgA(+) plasma cells in the small intestine of eosinophil-deficient ΔdblGATA-1 mice compared to eosinophil-sufficient wild-type mice, with the difference becoming significant post-infection with Toxoplasma gondii. Remarkably, and in complete contrast, the absence of eosinophils in the inflamed large intestine does not impact on IgA(+) cell numbers during steady state, and is associated with a significant increase in IgA(+) cells post-infection with Trichuris muris compared to wild-type mice. Thus, the intestinal eosinophil appears to be less important in sustaining the IgA(+) cell pool in the large intestine compared to the small intestine, and in fact, our data suggests eosinophils play an inhibitory role. The dichotomy in the influence of the eosinophil over small and large intestinal IgA(+) cells did not depend on differences in plasma cell growth factors, recruitment potential or proliferation within the different regions of the gastrointestinal tract (GIT). We demonstrate for the first time that there are regional differences in the requirement of eosinophils for maintaining IgA+ cells between the large and small intestine, which are more pronounced during inflammation. This is an important step towards further delineation of the enigmatic functions of gut-resident eosinophils.

Ionization-potential depression and dynamical structure factor in dense plasmas

NASA Astrophysics Data System (ADS)

Lin, Chengliang; Röpke, Gerd; Kraeft, Wolf-Dietrich; Reinholz, Heidi

2017-07-01

The properties of a bound electron system immersed in a plasma environment are strongly modified by the surrounding plasma. The modification of an essential quantity, the ionization energy, is described by the electronic and ionic self-energies, including dynamical screening within the framework of the quantum statistical theory. Introducing the ionic dynamical structure factor as the indicator for the ionic microfield, we demonstrate that ionic correlations and fluctuations play a critical role in determining the ionization potential depression. This is, in particular, true for mixtures of different ions with large mass and charge asymmetry. The ionization potential depression is calculated for dense aluminum plasmas as well as for a CH plasma and compared to the experimental data and more phenomenological approaches used so far.

Einstein coefficients and oscillator strengths for low lying state of CO molecules

NASA Astrophysics Data System (ADS)

Swer, S.; Syiemiong, A.; Ram, M.; Jha, A. K.; Saxena, A.

2018-04-01

Einstein Coefficients and Oscillator Strengths for different state of CO molecule have been calculated using LEROY'S LEVEL program and MOLCAS ab initio code. Using the wave function derived from Morse potential and transition dipole moment obtained from ab initio calculation, The potential energy functions were computed for these states using the spectroscopic constants. The Morse potential of these states and electronic transition dipole moment of the transition calculated in a recent ab initio study have been used in LEVEL program to produce transition dipole matrix element for a large number of bands. Einstein Coefficients have also been used to compute the radiative lifetimes of several vibrational levels and the calculated values are compared with other theoretical results and experimental values.

Comparison between epiphyte assemblages of leaves and rhizomes of the seagrass Posidonia oceanica subjected to different levels of anthropogenic eutrophication

NASA Astrophysics Data System (ADS)

Balata, David; Bertocci, Iacopo; Piazzi, Luigi; Nesti, Ugo

2008-09-01

This paper aimed to compare epiphyte assemblages of leaves and rhizomes of Posidonia oceanica exposed to different levels of concentration of nutrients. The same design including a potentially impacted meadow and two reference meadows was used in each of two locations, characterized by the presence of a city or of suspended cages of a fish farm, respectively. This allowed to test for the consistency of responses of epiphytic assemblages to different sources of eutrophication. In both studies, results documented differences in patterns of composition and abundance of epiphytic assemblages on leaves between disturbed and reference meadows, while assemblages on rhizomes did not appear sensitive to this kind of disturbance. Moreover, in potentially impacted meadows, both assemblages showed different patterns of spatial variability compared to reference assemblages. Species composition and abundance of epiphyte assemblages seemed suitable for detecting moderate nutrient increases, even if adequate sampling designs are needed to separate patterns related to the large natural spatial variability of these systems from those related to changes in environmental conditions.

Visual Word Recognition Across the Adult Lifespan

PubMed Central

Cohen-Shikora, Emily R.; Balota, David A.

2016-01-01

The current study examines visual word recognition in a large sample (N = 148) across the adult lifespan and across a large set of stimuli (N = 1187) in three different lexical processing tasks (pronunciation, lexical decision, and animacy judgments). Although the focus of the present study is on the influence of word frequency, a diverse set of other variables are examined as the system ages and acquires more experience with language. Computational models and conceptual theories of visual word recognition and aging make differing predictions for age-related changes in the system. However, these have been difficult to assess because prior studies have produced inconsistent results, possibly due to sample differences, analytic procedures, and/or task-specific processes. The current study confronts these potential differences by using three different tasks, treating age and word variables as continuous, and exploring the influence of individual differences such as vocabulary, vision, and working memory. The primary finding is remarkable stability in the influence of a diverse set of variables on visual word recognition across the adult age spectrum. This pattern is discussed in reference to previous inconsistent findings in the literature and implications for current models of visual word recognition. PMID:27336629

Are Current Atomistic Force Fields Accurate Enough to Study Proteins in Crowded Environments?

PubMed Central

Petrov, Drazen; Zagrovic, Bojan

2014-01-01

The high concentration of macromolecules in the crowded cellular interior influences different thermodynamic and kinetic properties of proteins, including their structural stabilities, intermolecular binding affinities and enzymatic rates. Moreover, various structural biology methods, such as NMR or different spectroscopies, typically involve samples with relatively high protein concentration. Due to large sampling requirements, however, the accuracy of classical molecular dynamics (MD) simulations in capturing protein behavior at high concentration still remains largely untested. Here, we use explicit-solvent MD simulations and a total of 6.4 µs of simulated time to study wild-type (folded) and oxidatively damaged (unfolded) forms of villin headpiece at 6 mM and 9.2 mM protein concentration. We first perform an exhaustive set of simulations with multiple protein molecules in the simulation box using GROMOS 45a3 and 54a7 force fields together with different types of electrostatics treatment and solution ionic strengths. Surprisingly, the two villin headpiece variants exhibit similar aggregation behavior, despite the fact that their estimated aggregation propensities markedly differ. Importantly, regardless of the simulation protocol applied, wild-type villin headpiece consistently aggregates even under conditions at which it is experimentally known to be soluble. We demonstrate that aggregation is accompanied by a large decrease in the total potential energy, with not only hydrophobic, but also polar residues and backbone contributing substantially. The same effect is directly observed for two other major atomistic force fields (AMBER99SB-ILDN and CHARMM22-CMAP) as well as indirectly shown for additional two (AMBER94, OPLS-AAL), and is possibly due to a general overestimation of the potential energy of protein-protein interactions at the expense of water-water and water-protein interactions. Overall, our results suggest that current MD force fields may distort the picture of protein behavior in biologically relevant crowded environments. PMID:24854339

Plastic efficiency of different implants used for repair of soft and bone tissue defects.

PubMed

Iriyanov, Yu M; Chernov, V F; Radchenko, S A; Chernov, A V

2013-08-01

The results of clinical and experimental morphological studies of regenerates forming after replacement of large defects of the abdominal wall and tibia with implants from different materials (polytetrafluoroethylene, reperene, prolene, titanium, and titanium nickelide) are analyzed. Study of the regenerate histology and fibroarchitectonics has shown good prospects of mesh constructions from titanium nickelide for effective surgical repair of these defects. The use of this implant seems to be theoretically well-based and promising, particularly under conditions of suppurative infection and low individual reparative regenerative potential.

Quantitative operando visualization of the energy band depth profile in solar cells.

PubMed

Chen, Qi; Mao, Lin; Li, Yaowen; Kong, Tao; Wu, Na; Ma, Changqi; Bai, Sai; Jin, Yizheng; Wu, Dan; Lu, Wei; Wang, Bing; Chen, Liwei

2015-07-13

The energy band alignment in solar cell devices is critically important because it largely governs elementary photovoltaic processes, such as the generation, separation, transport, recombination and collection of charge carriers. Despite the expenditure of considerable effort, the measurement of energy band depth profiles across multiple layers has been extremely challenging, especially for operando devices. Here we present direct visualization of the surface potential depth profile over the cross-sections of operando organic photovoltaic devices using scanning Kelvin probe microscopy. The convolution effect due to finite tip size and cantilever beam crosstalk has previously prohibited quantitative interpretation of scanning Kelvin probe microscopy-measured surface potential depth profiles. We develop a bias voltage-compensation method to address this critical problem and obtain quantitatively accurate measurements of the open-circuit voltage, built-in potential and electrode potential difference.

Quantitative operando visualization of the energy band depth profile in solar cells

PubMed Central

Chen, Qi; Mao, Lin; Li, Yaowen; Kong, Tao; Wu, Na; Ma, Changqi; Bai, Sai; Jin, Yizheng; Wu, Dan; Lu, Wei; Wang, Bing; Chen, Liwei

2015-01-01

The energy band alignment in solar cell devices is critically important because it largely governs elementary photovoltaic processes, such as the generation, separation, transport, recombination and collection of charge carriers. Despite the expenditure of considerable effort, the measurement of energy band depth profiles across multiple layers has been extremely challenging, especially for operando devices. Here we present direct visualization of the surface potential depth profile over the cross-sections of operando organic photovoltaic devices using scanning Kelvin probe microscopy. The convolution effect due to finite tip size and cantilever beam crosstalk has previously prohibited quantitative interpretation of scanning Kelvin probe microscopy-measured surface potential depth profiles. We develop a bias voltage-compensation method to address this critical problem and obtain quantitatively accurate measurements of the open-circuit voltage, built-in potential and electrode potential difference. PMID:26166580

Real-time estimation and biofeedback of single-neuron firing rates using local field potentials

PubMed Central

Hall, Thomas M.; Nazarpour, Kianoush; Jackson, Andrew

2014-01-01

The long-term stability and low-frequency composition of local field potentials (LFPs) offer important advantages for robust and efficient neuroprostheses. However, cortical LFPs recorded by multi-electrode arrays are often assumed to contain only redundant information arising from the activity of large neuronal populations. Here we show that multichannel LFPs in monkey motor cortex each contain a slightly different mixture of distinctive slow potentials that accompany neuronal firing. As a result, the firing rates of individual neurons can be estimated with surprising accuracy. We implemented this method in a real-time biofeedback brain–machine interface, and found that monkeys could learn to modulate the activity of arbitrary neurons using feedback derived solely from LFPs. These findings provide a principled method for monitoring individual neurons without long-term recording of action potentials. PMID:25394574

Predicting potential global distributions of two Miscanthus grasses: implications for horticulture, biofuel production, and biological invasions.

PubMed

Hager, Heather A; Sinasac, Sarah E; Gedalof, Ze'ev; Newman, Jonathan A

2014-01-01

In many regions, large proportions of the naturalized and invasive non-native floras were originally introduced deliberately by humans. Pest risk assessments are now used in many jurisdictions to regulate the importation of species and usually include an estimation of the potential distribution in the import area. Two species of Asian grass (Miscanthus sacchariflorus and M. sinensis) that were originally introduced to North America as ornamental plants have since escaped cultivation. These species and their hybrid offspring are now receiving attention for large-scale production as biofuel crops in North America and elsewhere. We evaluated their potential global climate suitability for cultivation and potential invasion using the niche model CLIMEX and evaluated the models' sensitivity to the parameter values. We then compared the sensitivity of projections of future climatically suitable area under two climate models and two emissions scenarios. The models indicate that the species have been introduced to most of the potential global climatically suitable areas in the northern but not the southern hemisphere. The more narrowly distributed species (M. sacchariflorus) is more sensitive to changes in model parameters, which could have implications for modelling species of conservation concern. Climate projections indicate likely contractions in potential range in the south, but expansions in the north, particularly in introduced areas where biomass production trials are under way. Climate sensitivity analysis shows that projections differ more between the selected climate change models than between the selected emissions scenarios. Local-scale assessments are required to overlay suitable habitat with climate projections to estimate areas of cultivation potential and invasion risk.

Mapping opportunities and challenges for rewilding in Europe.

PubMed

Ceaușu, Silvia; Hofmann, Max; Navarro, Laetitia M; Carver, Steve; Verburg, Peter H; Pereira, Henrique M

2015-08-01

Farmland abandonment takes place across the world due to socio-economic and ecological drivers. In Europe agricultural and environmental policies aim to prevent abandonment and halt ecological succession. Ecological rewilding has been recently proposed as an alternative strategy. We developed a framework to assess opportunities for rewilding across different dimensions of wilderness in Europe. We mapped artificial light, human accessibility based on transport infrastructure, proportion of harvested primary productivity (i.e., ecosystem productivity appropriated by humans through agriculture or forestry), and deviation from potential natural vegetation in areas projected to be abandoned by 2040. At the continental level, the levels of artificial light were low and the deviation from potential natural vegetation was high in areas of abandonment. The relative importance of wilderness metrics differed regionally and was strongly connected to local environmental and socio-economic contexts. Large areas of projected abandonment were often located in or around Natura 2000 sites. Based on these results, we argue that management should be tailored to restore the aspects of wilderness that are lacking in each region. There are many remaining challenges regarding biodiversity in Europe, but megafauna species are already recovering. To further potentiate large-scale rewilding, Natura 2000 management would need to incorporate rewilding approaches. Our framework can be applied to assessing rewilding opportunities and challenges in other world regions, and our results could guide redirection of subsidies to manage social-ecological systems. © 2015 The Authors. Conservation Biology published by wiley Periodicals, Inc. on behalf of the Society for Conservation Biology.

Meteorology and Wake Vortex Influence on American Airlines FL-587 Accident

NASA Technical Reports Server (NTRS)

Proctor, Fred H.; Hamilton, David W.; Rutishauser, David K.; Switzer, George F.

2004-01-01

The atmospheric environment surrounding the crash of American Airlines Flight 587 is investigated. Examined are evidence for any unusual atmospheric conditions and the potential for encounters with aircraft wake vortices. Computer simulations are carried out with two different vortex prediction models and a Large Eddy Simulation model. Wind models are proposed for studying aircraft and pilot response to the wake vortex encounter.

Tasting Words and Letting Them Hang in the Air. About Subject-Oriented Language in Kindergarten

ERIC Educational Resources Information Center

Askeland, Norunn; Maagero, Eva

2010-01-01

In the first part of this article we will briefly point out the learning areas in the Norwegian Framework plan for contents and tasks in kindergartens from 2006, and argue that the introduction of these areas means a large potential for focusing on different kinds of subject-oriented language in kindergarten. We will present some features of…

Customization of Discriminant Function Analysis for Prediction of Solar Flares

DTIC Science & Technology

2005-03-01

lives such as telecommunication, commercial airlines, electrical power , wireless services, and terrestrial weather tracking and forecasting...the 1800’s can wreak havoc on today’s power , fuel, and telecommunication lines and finds its origin in solar activity. Enormous amounts of solar...inducing potential differences across large areas of the surface. Earth-bound power , fuel, and telecommunication lines grounded to the Earth provide an

Ground-Based High-Power Microwave Decoy Discrimination System.

DTIC Science & Technology

1987-12-23

understanding of plasma instabilities, self-induced magnetic effects , space - charge considerations, production of ion currents, etc. 3.3.4 Cross-Field...breakdown, due to small potential differences. Interaction volumes can therefore be large, avoiding breakdown and space - charge effects (at the price...the interference of the incident and reflected wave, and by the electrostatic forces of the surface (positive) and space charge (negative) trapped in

Occurrence modes of As, Sb, Te, Bi, Ag in sulfide assemblages of gold deposits of the Urals

NASA Astrophysics Data System (ADS)

Vikent'eva, O.; Vikentev, I.

2016-04-01

Review of occurrence modes of trace toxic elements ("potential pollutants") in ores from large gold deposits (the Urals) of different genetic types is presented. Mineral forms of these elements as well as their presence in main minerals from gold-bearing sulfide assemblages according to SEM, EPMA, INAA, ICP-MS and LA-ICP-MS are demonstrated.

Attrition in a Large Scale Longitudinal Study of the Elderly: The Role of Health-Status Variables.

ERIC Educational Resources Information Center

Horgas, Ann L.; And Others

In a longitudinal study, subject attrition constitutes a potential threat to the usefulness of data collected from subjects remaining in later waves of the study. If attrition is selective, then the sample at later waves of the study may be representative of a different population than that represented at the outset of the study. This study…

Tapered holey fibers for spot-size and numerical-aperture conversion.

PubMed

Town, G E; Lizier, J T

2001-07-15

Adiabatically tapered holey fibers are shown to be potentially useful for guided-wave spot-size and numerical-aperture conversion. Conditions for adiabaticity and design guidelines are provided in terms of the effective-index model. We also present finite-difference time-domain calculations of downtapered holey fiber, showing that large spot-size conversion factors are obtainable with minimal loss by use of short, optimally shaped tapers.

Differences between brain mass and body weight scaling to height: potential mechanism of reduced mass-specific resting energy expenditure of taller adults.

PubMed

Heymsfield, Steven B; Chirachariyavej, Thamrong; Rhyu, Im Joo; Roongpisuthipong, Chulaporn; Heo, Moonseong; Pietrobelli, Angelo

2009-01-01

Adult resting energy expenditure (REE) scales as height( approximately 1.5), whereas body weight (BW) scales as height( approximately 2). Mass-specific REE (i.e., REE/BW) is thus lower in tall subjects compared with their shorter counterparts, the mechanism of which is unknown. We evaluated the hypothesis that high-metabolic-rate brain mass scales to height with a power significantly less than that of BW, a theory that if valid would provide a potential mechanism for height-related REE effects. The hypothesis was tested by measuring brain mass on a large (n = 372) postmortem sample of Thai men. Since brain mass-body size relations may be influenced by age, the hypothesis was secondarily explored in Thai men age < or =45 yr (n = 299) and with brain magnetic resonance imaging (MRI) studies in Korean men (n = 30) age > or =20<30 yr. The scaling of large body compartments was examined in a third group of Asian men living in New York (NY, n = 28) with MRI and dual-energy X-ray absorptiometry. Brain mass scaled to height with a power (mean +/- SEE; 0.46 +/- 0.13) significantly smaller (P < 0.001) than that of BW scaled to height (2.36 +/- 0.19) in the whole group of Thai men; brain mass/BW scaled negatively to height (-1.94 +/- 0.20, P < 0.001). Similar results were observed in younger Thai men, and results for brain mass/BW vs. height were directionally the same (P = 0.09) in Korean men. Skeletal muscle and bone scaled to height with powers similar to that of BW (i.e., approximately 2-3) in the NY Asian men. Models developed using REE estimates in Thai men suggest that brain accounts for most of the REE/BW height dependency. Tall and short men thus differ in relative brain mass, but the proportions of BW as large compartments appear independent of height, observations that provide a potential mechanistic basis for related differences in REE and that have implications for the study of adult energy requirements.

Avian Influenza Virus Surveillance in High Arctic Breeding Geese, Greenland.

PubMed

Gaidet, Nicolas; Leclercq, India; Batéjat, Christophe; Grassin, Quentin; Daufresne, Tanguy; Manuguerra, Jean-Claude

2018-06-01

The connectedness in Arctic regions between migratory waterbird populations originating from different continents and the potential for virus exchange at their shared Arctic breeding ground point to the need to explore the largely unstudied circumpolar circulation of avian influenza viruses (AIV). We here report the investigation of AIV in wild birds and lakes in a high Arctic area of Northeast Greenland. No AIV could be detected in the fecal, feather, and water samples collected from large flocks of pink-footed geese Anser brachyrhynchus and barnacle geese Branta leucopsis in and around refuge lakes, where they congregate at high density during their flightless molting period in summer.

Treatment of anemia in chronic kidney disease: known, unknown, and both.

PubMed

Foley, Robert N

2011-01-01

Erythropoiesis is a rapidly evolving research arena and several mechanistic insights show therapeutic promise. In contrast with the rapid advance of mechanistic science, optimal management of anemia in patients with chronic kidney disease remains a difficult and polarizing issue. Although several large hemoglobin target trials have been performed, optimal treatment targets remain elusive, because none of the large trials to date have unequivocally identified differences in primary outcome rates or death rates, and because other reported outcomes indicate the potential for harm (rates of stroke, early requirement for dialysis, and vascular access thrombosis) and benefit (reductions in transfusion requirements and fatigue).

Uncertainty in flood damage estimates and its potential effect on investment decisions

NASA Astrophysics Data System (ADS)

Wagenaar, D. J.; de Bruijn, K. M.; Bouwer, L. M.; de Moel, H.

2016-01-01

This paper addresses the large differences that are found between damage estimates of different flood damage models. It explains how implicit assumptions in flood damage functions and maximum damages can have large effects on flood damage estimates. This explanation is then used to quantify the uncertainty in the damage estimates with a Monte Carlo analysis. The Monte Carlo analysis uses a damage function library with 272 functions from seven different flood damage models. The paper shows that the resulting uncertainties in estimated damages are in the order of magnitude of a factor of 2 to 5. The uncertainty is typically larger for flood events with small water depths and for smaller flood events. The implications of the uncertainty in damage estimates for flood risk management are illustrated by a case study in which the economic optimal investment strategy for a dike segment in the Netherlands is determined. The case study shows that the uncertainty in flood damage estimates can lead to significant over- or under-investments.

Walking in Two French Neighborhoods: A Study of How Park Numbers and Locations Relate to Everyday Walking

PubMed Central

Rioux, Liliane; Werner, Carol M.; Mokounkolo, Rene; Brown, Barbara B.

2017-01-01

Research indicates that people are drawn to green spaces with attractive amenities. This study extends that finding by comparing walking patterns in two neighborhoods with different numbers of parks; parks did not differ in rated attractiveness nor did neighborhoods differ substantially in rated walkability. Adults, aged 32–86 years (n = 90), drew their 3 most recent walking routes on maps of their neighborhood. Analyses showed that participants’ round trips were longer by 265.5 meters (.16 mile) in the neighborhood with a single, large, centrally located park (p < .02). However, participants in the neighborhood with multiple, small, more distributed parks, visited more streets, p < .001, more streets with green spaces, p < .038, and used more varied routes, p < .012. Results suggest there are potential benefits to both layouts. Large centralized parks may invite longer walks; smaller, well-distributed parks may invite more varied routes suggestive of appropriation and motivation processes. Both layouts might be combined in a single neighborhood to attract more walkers. PMID:28579664

Positional error and time-activity patterns in near-highway proximity studies: an exposure misclassification analysis

PubMed Central

2013-01-01

Background The growing interest in research on the health effects of near-highway air pollutants requires an assessment of potential sources of error in exposure assignment techniques that rely on residential proximity to roadways. Methods We compared the amount of positional error in the geocoding process for three different data sources (parcels, TIGER and StreetMap USA) to a “gold standard” residential geocoding process that used ortho-photos, large multi-building parcel layouts or large multi-unit building floor plans. The potential effect of positional error for each geocoding method was assessed as part of a proximity to highway epidemiological study in the Boston area, using all participants with complete address information (N = 703). Hourly time-activity data for the most recent workday/weekday and non-workday/weekend were collected to examine time spent in five different micro-environments (inside of home, outside of home, school/work, travel on highway, and other). Analysis included examination of whether time-activity patterns were differentially distributed either by proximity to highway or across demographic groups. Results Median positional error was significantly higher in street network geocoding (StreetMap USA = 23 m; TIGER = 22 m) than parcel geocoding (8 m). When restricted to multi-building parcels and large multi-unit building parcels, all three geocoding methods had substantial positional error (parcels = 24 m; StreetMap USA = 28 m; TIGER = 37 m). Street network geocoding also differentially introduced greater amounts of positional error in the proximity to highway study in the 0–50 m proximity category. Time spent inside home on workdays/weekdays differed significantly by demographic variables (age, employment status, educational attainment, income and race). Time-activity patterns were also significantly different when stratified by proximity to highway, with those participants residing in the 0–50 m proximity category reporting significantly more time in the school/work micro-environment on workdays/weekdays than all other distance groups. Conclusions These findings indicate the potential for both differential and non-differential exposure misclassification due to geocoding error and time-activity patterns in studies of highway proximity. We also propose a multi-stage manual correction process to minimize positional error. Additional research is needed in other populations and geographic settings. PMID:24010639

Positional error and time-activity patterns in near-highway proximity studies: an exposure misclassification analysis.

PubMed

Lane, Kevin J; Kangsen Scammell, Madeleine; Levy, Jonathan I; Fuller, Christina H; Parambi, Ron; Zamore, Wig; Mwamburi, Mkaya; Brugge, Doug

2013-09-08

The growing interest in research on the health effects of near-highway air pollutants requires an assessment of potential sources of error in exposure assignment techniques that rely on residential proximity to roadways. We compared the amount of positional error in the geocoding process for three different data sources (parcels, TIGER and StreetMap USA) to a "gold standard" residential geocoding process that used ortho-photos, large multi-building parcel layouts or large multi-unit building floor plans. The potential effect of positional error for each geocoding method was assessed as part of a proximity to highway epidemiological study in the Boston area, using all participants with complete address information (N = 703). Hourly time-activity data for the most recent workday/weekday and non-workday/weekend were collected to examine time spent in five different micro-environments (inside of home, outside of home, school/work, travel on highway, and other). Analysis included examination of whether time-activity patterns were differentially distributed either by proximity to highway or across demographic groups. Median positional error was significantly higher in street network geocoding (StreetMap USA = 23 m; TIGER = 22 m) than parcel geocoding (8 m). When restricted to multi-building parcels and large multi-unit building parcels, all three geocoding methods had substantial positional error (parcels = 24 m; StreetMap USA = 28 m; TIGER = 37 m). Street network geocoding also differentially introduced greater amounts of positional error in the proximity to highway study in the 0-50 m proximity category. Time spent inside home on workdays/weekdays differed significantly by demographic variables (age, employment status, educational attainment, income and race). Time-activity patterns were also significantly different when stratified by proximity to highway, with those participants residing in the 0-50 m proximity category reporting significantly more time in the school/work micro-environment on workdays/weekdays than all other distance groups. These findings indicate the potential for both differential and non-differential exposure misclassification due to geocoding error and time-activity patterns in studies of highway proximity. We also propose a multi-stage manual correction process to minimize positional error. Additional research is needed in other populations and geographic settings.

The Sabah Biodiversity Experiment: a long-term test of the role of tree diversity in restoring tropical forest structure and functioning

PubMed Central

Hector, Andy; Philipson, Christopher; Saner, Philippe; Chamagne, Juliette; Dzulkifli, Dzaeman; O'Brien, Michael; Snaddon, Jake L.; Ulok, Philip; Weilenmann, Maja; Reynolds, Glen; Godfray, H. Charles J.

2011-01-01

Relatively, little is known about the relationship between biodiversity and ecosystem functioning in forests, especially in the tropics. We describe the Sabah Biodiversity Experiment: a large-scale, long-term field study on the island of Borneo. The project aims at understanding the relationship between tree species diversity and the functioning of lowland dipterocarp rainforest during restoration following selective logging. The experiment is planned to run for several decades (from seed to adult tree), so here we focus on introducing the project and its experimental design and on assessing initial conditions and the potential for restoration of the structure and functioning of the study system, the Malua Forest Reserve. We estimate residual impacts 22 years after selective logging by comparison with an appropriate neighbouring area of primary forest in Danum Valley of similar conditions. There was no difference in the alpha or beta species diversity of transect plots in the two forest types, probably owing to the selective nature of the logging and potential effects of competitive release. However, despite equal total stem density, forest structure differed as expected with a deficit of large trees and a surfeit of saplings in selectively logged areas. These impacts on structure have the potential to influence ecosystem functioning. In particular, above-ground biomass and carbon pools in selectively logged areas were only 60 per cent of those in the primary forest even after 22 years of recovery. Our results establish the initial conditions for the Sabah Biodiversity Experiment and confirm the potential to accelerate restoration by using enrichment planting of dipterocarps to overcome recruitment limitation. What role dipterocarp diversity plays in restoration only will become clear with long-term results. PMID:22006970

Orbital structure in oscillating galactic potentials

NASA Astrophysics Data System (ADS)

Terzić, Balša; Kandrup, Henry E.

2004-01-01

Subjecting a galactic potential to (possibly damped) nearly periodic, time-dependent variations can lead to large numbers of chaotic orbits experiencing systematic changes in energy, and the resulting chaotic phase mixing could play an important role in explaining such phenomena as violent relaxation. This paper focuses on the simplest case of spherically symmetric potentials subjected to strictly periodic driving with the aim of understanding precisely why orbits become chaotic and under what circumstances they will exhibit systematic changes in energy. Four unperturbed potentials V0(r) were considered, each subjected to a time dependence of the form V(r, t) =V0(r)(1 +m0 sinωt). In each case, the orbits divide clearly into regular and chaotic, distinctions which appear absolute. In particular, transitions from regularity to chaos are seemingly impossible. Over finite time intervals, chaotic orbits subdivide into what can be termed `sticky' chaotic orbits, which exhibit no large-scale secular changes in energy and remain trapped in the phase-space region where they started; and `wildly' chaotic orbits, which do exhibit systematic drifts in energy as the orbits diffuse to different phase-space regions. This latter distinction is not absolute, transitions corresponding apparently to orbits penetrating a `leaky' phase-space barrier. The three different orbit types can be identified simply in terms of the frequencies for which their Fourier spectra have the most power. An examination of the statistical properties of orbit ensembles as a function of driving frequency ω allows us to identify the specific resonances that determine orbital structure. Attention focuses also on how, for fixed amplitude m0, such quantities as the mean energy shift, the relative measure of chaotic orbits and the mean value of the largest Lyapunov exponent vary with driving frequency ω and how, for fixed ω, the same quantities depend on m0.

The Sabah Biodiversity Experiment: a long-term test of the role of tree diversity in restoring tropical forest structure and functioning.

PubMed

Hector, Andy; Philipson, Christopher; Saner, Philippe; Chamagne, Juliette; Dzulkifli, Dzaeman; O'Brien, Michael; Snaddon, Jake L; Ulok, Philip; Weilenmann, Maja; Reynolds, Glen; Godfray, H Charles J

2011-11-27

Relatively, little is known about the relationship between biodiversity and ecosystem functioning in forests, especially in the tropics. We describe the Sabah Biodiversity Experiment: a large-scale, long-term field study on the island of Borneo. The project aims at understanding the relationship between tree species diversity and the functioning of lowland dipterocarp rainforest during restoration following selective logging. The experiment is planned to run for several decades (from seed to adult tree), so here we focus on introducing the project and its experimental design and on assessing initial conditions and the potential for restoration of the structure and functioning of the study system, the Malua Forest Reserve. We estimate residual impacts 22 years after selective logging by comparison with an appropriate neighbouring area of primary forest in Danum Valley of similar conditions. There was no difference in the alpha or beta species diversity of transect plots in the two forest types, probably owing to the selective nature of the logging and potential effects of competitive release. However, despite equal total stem density, forest structure differed as expected with a deficit of large trees and a surfeit of saplings in selectively logged areas. These impacts on structure have the potential to influence ecosystem functioning. In particular, above-ground biomass and carbon pools in selectively logged areas were only 60 per cent of those in the primary forest even after 22 years of recovery. Our results establish the initial conditions for the Sabah Biodiversity Experiment and confirm the potential to accelerate restoration by using enrichment planting of dipterocarps to overcome recruitment limitation. What role dipterocarp diversity plays in restoration only will become clear with long-term results.

Consensus on criteria for potential areas for wolf reintroduction in Mexico.

PubMed

Araiza, Marcela; Carrillo, Luis; List, Rurik; González, Carlos A López; Meyer, Enrique Martínez; Martínez-Gutiérrez, Patricia G; Moctezuma, Oscar; Sánchez-Morales, Nahum E; Servín, Jorge

2012-08-01

Given the conflict with human interests that in many cases results in the extirpation of large carnivores, acceptance of their reintroduction is a considerable challenge. By the 1980s Mexican wolves (Canis lupus) were extinct in the wild. In 1998 a population was reintroduced in the Blue Range Mountains of New Mexico (U.S.A.). Efforts to reintroduce the species in Mexico have been ongoing since the late 1980s. Four teams working independently identified 6 areas in northern Mexico in the historic range of Mexican wolves, where reintroductions could potentially be successful. Each team used different methods and criteria to identify the areas, which makes it difficult to prioritize among these areas. Therefore, members of the different teams worked together to devise criteria for use in identifying priority areas. They identified areas with high, intermediate, and low potential levels of conflict between wolves and humans. Areas with low potential conflict had larger buffers (i.e., distance from human settlement to areas suitable for wolves) around human settlements than high- and intermediate-conflict areas and thus were thought most appropriate for the first reintroduction. High-conflict areas contained habitat associated with wolf presence, but were closer to human activity. The first reintroduction of Mexican wolves to Mexico occurred in October 2011 in one of the identified low-conflict areas. The identification of suitable areas for reintroduction represents a crucial step in the process toward the restoration of large carnivores. Choice of the first reintroduction area can determine whether the reintroduction is successful or fails. A failure may preclude future reintroduction efforts in a region or country. ©2012 Society for Conservation Biology.

New probiotic strains for inflammatory bowel disease management identified by combining in vitro and in vivo approaches.

PubMed

Alard, J; Peucelle, V; Boutillier, D; Breton, J; Kuylle, S; Pot, B; Holowacz, S; Grangette, C

2018-02-27

Alterations in the gut microbiota composition play a key role in the development of chronic diseases such as inflammatory bowel disease (IBD). The potential use of probiotics therefore gained attention, although outcomes were sometimes conflicting and results largely strain-dependent. The present study aimed to identify new probiotic strains that have a high potential for the management of this type of pathologies. Strains were selected from a large collection by combining different in vitro and in vivo approaches, addressing both anti-inflammatory potential and ability to improve the gut barrier function. We identified six strains with an interesting anti-inflammatory profile on peripheral blood mononuclear cells and with the ability to restore the gut barrier using a gut permeability model based on Caco-2 cells sensitized with hydrogen peroxide. The in vivo evaluation in two 2,4,6-trinitrobenzene sulfonic acid-induced murine models of colitis highlighted that some of the strains exhibited beneficial activities against acute colitis while others improved chronic colitis. Bifidobacterium bifidum PI22, the strain that exhibited the most protective capacities against acute colitis was only slightly efficacious against chronic colitis, while Bifidobacterium lactis LA804 which was less efficacious in the acute model was the most protective against chronic colitis. Lactobacillus helveticus PI5 was not anti-inflammatory in vitro but the best in strengthening the epithelial barrier and as such able to significantly dampen murine acute colitis. Interestingly, Lactobacillus salivarius LA307 protected mice significantly against both types of colitis. This work provides crucial clues for selecting the best strains for more efficacious therapeutic approaches in the management of chronic inflammatory diseases. The strategy employed allowed us to identify four strains with different characteristics and a high potential for the management of inflammatory diseases, such as IBD.

Alternative derivation of an exchange-only density-functional optimized effective potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joubert, D. P.

2007-10-15

An alternative derivation of the exchange-only density-functional optimized effective potential equation is given. It is shown that the localized Hartree-Fock-common energy denominator Green's function approximation (LHF-CEDA) for the density-functional exchange potential proposed independently by Della Sala and Goerling [J. Chem. Phys. 115, 5718 (2001)] and Gritsenko and Baerends [Phys. Rev. A 64, 42506 (2001)] can be derived as an approximation to the OEP exchange potential in a similar way that the KLI approximation [Phys. Rev. A 45, 5453 (1992)] was derived. An exact expression for the correction term to the LHF-CEDA approximation can thus be found. The correction term canmore » be expressed in terms of the first-order perturbation-theory many-electron wave function shift when the Kohn-Sham Hamiltonian is subjected to a perturbation equal to the difference between the density-functional exchange potential and the Hartree-Fock nonlocal potential, expressed in terms of the Kohn-Sham orbitals. An explicit calculation shows that the density weighted mean of the correction term is zero, confirming that the LHF-CEDA approximation can be interpreted as a mean-field approximation. The corrected LHF-CEDA equation and the optimized effective potential equation are shown to be identical, with information distributed differently between terms in the equations. For a finite system the correction term falls off at least as fast as 1/r{sup 4} for large r.« less

Alternative derivation of an exchange-only density-functional optimized effective potential

NASA Astrophysics Data System (ADS)

Joubert, D. P.

2007-10-01

An alternative derivation of the exchange-only density-functional optimized effective potential equation is given. It is shown that the localized Hartree-Fock common energy denominator Green’s function approximation (LHF-CEDA) for the density-functional exchange potential proposed independently by Della Sala and Görling [J. Chem. Phys. 115, 5718 (2001)] and Gritsenko and Baerends [Phys. Rev. A 64, 42506 (2001)] can be derived as an approximation to the OEP exchange potential in a similar way that the KLI approximation [Phys. Rev. A 45, 5453 (1992)] was derived. An exact expression for the correction term to the LHF-CEDA approximation can thus be found. The correction term can be expressed in terms of the first-order perturbation-theory many-electron wave function shift when the Kohn-Sham Hamiltonian is subjected to a perturbation equal to the difference between the density-functional exchange potential and the Hartree-Fock nonlocal potential, expressed in terms of the Kohn-Sham orbitals. An explicit calculation shows that the density weighted mean of the correction term is zero, confirming that the LHF-CEDA approximation can be interpreted as a mean-field approximation. The corrected LHF-CEDA equation and the optimized effective potential equation are shown to be identical, with information distributed differently between terms in the equations. For a finite system the correction term falls off at least as fast as 1/r4 for large r .

Polishers around the globe: an overview on the market of large astronomical mirrors

NASA Astrophysics Data System (ADS)

Döhring, Thorsten

2014-07-01

Astronomical mirrors are key elements in modern optical telescopes, their dimensions are usually large and their specifications are demanding. Only a limited number of skilled companies respectively institutions around the world are able to master the challenge to polish an individual astronomical mirror, especially in dimensions above one meter. This paper presents an overview on the corresponding market including a listing of polishers around the globe. Therefore valuable information is provided to the astronomical community: Polishers may use the information as a global competitor database, astronomers and project managers may get more transparency on potential suppliers, and suppliers of polishing equipment may learn about unknown potential customers in other parts of the world. An evaluation of the historical market demand on large monolithic astronomical mirrors is presented. It concluded that this is still a niche market with a typical mean rate of 1-2 mirrors per year. Polishing of such mirrors is an enabling technology with impact on the development of technical know-how, public relation, visibility and reputation of the supplier. Within a corresponding technical discussion different polishing technologies are described. In addition it is demonstrated that strategic aspects and political considerations are influencing the selection of the optical finisher.

Single field double inflation and primordial black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kannike, K.; Marzola, L.; Raidal, M.

Within the framework of scalar-tensor theories, we study the conditions that allow single field inflation dynamics on small cosmological scales to significantly differ from that of the large scales probed by the observations of cosmic microwave background. The resulting single field double inflation scenario is characterised by two consequent inflation eras, usually separated by a period where the slow-roll approximation fails. At large field values the dynamics of the inflaton is dominated by the interplay between its non-minimal coupling to gravity and the radiative corrections to the inflaton self-coupling. For small field values the potential is, instead, dominated by amore » polynomial that results in a hilltop inflation. Without relying on the slow-roll approximation, which is invalidated by the appearance of the intermediate stage, we propose a concrete model that matches the current measurements of inflationary observables and employs the freedom granted by the framework on small cosmological scales to give rise to a sizeable population of primordial black holes generated by large curvature fluctuations. We find that these features generally require a potential with a local minimum. We show that the associated primordial black hole mass function is only approximately lognormal.« less

Techniques for extracting single-trial activity patterns from large-scale neural recordings

PubMed Central

Churchland, Mark M; Yu, Byron M; Sahani, Maneesh; Shenoy, Krishna V

2008-01-01

Summary Large, chronically-implanted arrays of microelectrodes are an increasingly common tool for recording from primate cortex, and can provide extracellular recordings from many (order of 100) neurons. While the desire for cortically-based motor prostheses has helped drive their development, such arrays also offer great potential to advance basic neuroscience research. Here we discuss the utility of array recording for the study of neural dynamics. Neural activity often has dynamics beyond that driven directly by the stimulus. While governed by those dynamics, neural responses may nevertheless unfold differently for nominally identical trials, rendering many traditional analysis methods ineffective. We review recent studies – some employing simultaneous recording, some not – indicating that such variability is indeed present both during movement generation, and during the preceding premotor computations. In such cases, large-scale simultaneous recordings have the potential to provide an unprecedented view of neural dynamics at the level of single trials. However, this enterprise will depend not only on techniques for simultaneous recording, but also on the use and further development of analysis techniques that can appropriately reduce the dimensionality of the data, and allow visualization of single-trial neural behavior. PMID:18093826

Aqueous Two-Phase Systems at Large Scale: Challenges and Opportunities.

PubMed

Torres-Acosta, Mario A; Mayolo-Deloisa, Karla; González-Valdez, José; Rito-Palomares, Marco

2018-06-07

Aqueous two-phase systems (ATPS) have proved to be an efficient and integrative operation to enhance recovery of industrially relevant bioproducts. After ATPS discovery, a variety of works have been published regarding their scaling from 10 to 1000 L. Although ATPS have achieved high recovery and purity yields, there is still a gap between their bench-scale use and potential industrial applications. In this context, this review paper critically analyzes ATPS scale-up strategies to enhance the potential industrial adoption. In particular, large-scale operation considerations, different phase separation procedures, the available optimization techniques (univariate, response surface methodology, and genetic algorithms) to maximize recovery and purity and economic modeling to predict large-scale costs, are discussed. ATPS intensification to increase the amount of sample to process at each system, developing recycling strategies and creating highly efficient predictive models, are still areas of great significance that can be further exploited with the use of high-throughput techniques. Moreover, the development of novel ATPS can maximize their specificity increasing the possibilities for the future industry adoption of ATPS. This review work attempts to present the areas of opportunity to increase ATPS attractiveness at industrial levels. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rate/state Coulomb stress transfer model for the CSEP Japan seismicity forecast

NASA Astrophysics Data System (ADS)

Toda, Shinji; Enescu, Bogdan

2011-03-01

Numerous studies retrospectively found that seismicity rate jumps (drops) by coseismic Coulomb stress increase (decrease). The Collaboratory for the Study of Earthquake Prediction (CSEP) instead provides us an opportunity for prospective testing of the Coulomb hypothesis. Here we adapt our stress transfer model incorporating rate and state dependent friction law to the CSEP Japan seismicity forecast. We demonstrate how to compute the forecast rates of large shocks in 2009 using the large earthquakes during the past 120 years. The time dependent impact of the coseismic stress perturbations explains qualitatively well the occurrence of the recent moderate size shocks. Such ability is partly similar to that of statistical earthquake clustering models. However, our model differs from them as follows: the off-fault aftershock zones can be simulated using finite fault sources; the regional areal patterns of triggered seismicity are modified by the dominant mechanisms of the potential sources; the imparted stresses due to large earthquakes produce stress shadows that lead to a reduction of the forecasted number of earthquakes. Although the model relies on several unknown parameters, it is the first physics based model submitted to the CSEP Japan test center and has the potential to be tuned for short-term earthquake forecasts.

The BACnet Campus Challenge - Part 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masica, Ken; Tom, Steve

Here, the BACnet protocol was designed to achieve interoperability among building automation vendors and evolve over time to include new functionality as well as support new communication technologies such as the Ethernet and IP protocols as they became prevalent and economical in the market place. For large multi-building, multi-vendor campus environments, standardizing on the BACnet protocol as an implementation strategy can be a key component in meeting the challenge of an interoperable, flexible, and scalable building automation system. The interoperability of BACnet is especially important when large campuses with legacy equipment have DDC upgrades to facilities performed over different timemore » frames and use different contractors that install equipment from different vendors under the guidance of different campus HVAC project managers. In these circumstances, BACnet can serve as a common foundation for interoperability when potential variability exists in approaches to the design-build process by numerous parties over time. Likewise, BACnet support for a range of networking protocols and technologies can be a key strategy for achieving flexible and scalable automation systems as campuses and enterprises expand networking infrastructures using standard interoperable protocols like IP and Ethernet.« less

The BACnet Campus Challenge - Part 1

DOE PAGES

Masica, Ken; Tom, Steve

2015-12-01

Here, the BACnet protocol was designed to achieve interoperability among building automation vendors and evolve over time to include new functionality as well as support new communication technologies such as the Ethernet and IP protocols as they became prevalent and economical in the market place. For large multi-building, multi-vendor campus environments, standardizing on the BACnet protocol as an implementation strategy can be a key component in meeting the challenge of an interoperable, flexible, and scalable building automation system. The interoperability of BACnet is especially important when large campuses with legacy equipment have DDC upgrades to facilities performed over different timemore » frames and use different contractors that install equipment from different vendors under the guidance of different campus HVAC project managers. In these circumstances, BACnet can serve as a common foundation for interoperability when potential variability exists in approaches to the design-build process by numerous parties over time. Likewise, BACnet support for a range of networking protocols and technologies can be a key strategy for achieving flexible and scalable automation systems as campuses and enterprises expand networking infrastructures using standard interoperable protocols like IP and Ethernet.« less

Recovering the fine structures in solar images

NASA Technical Reports Server (NTRS)

Karovska, Margarita; Habbal, S. R.; Golub, L.; Deluca, E.; Hudson, Hugh S.

1994-01-01

Several examples of the capability of the blind iterative deconvolution (BID) technique to recover the real point spread function, when limited a priori information is available about its characteristics. To demonstrate the potential of image post-processing for probing the fine scale and temporal variability of the solar atmosphere, the BID technique is applied to different samples of solar observations from space. The BID technique was originally proposed for correction of the effects of atmospheric turbulence on optical images. The processed images provide a detailed view of the spatial structure of the solar atmosphere at different heights in regions with different large-scale magnetic field structures.

Polymer separations by liquid interaction chromatography: principles - prospects - limitations.

PubMed

Radke, Wolfgang

2014-03-28

Most heterogeneities of polymers with respect to different structural features cannot be resolved by only size exclusion chromatography (SEC), the most frequently applied mode of polymer chromatography. Instead, methods of interaction chromatography became increasingly important. However, despite the increasing applications the principles and potential of polymer interaction chromatography are still often unknown to a large number of polymer scientists. The present review will explain the principles of the different modes of polymer chromatography. Based on selected examples it will be shown which separation techniques can be successfully applied for separations with respect to the different structural features of polymers. Copyright © 2013 Elsevier B.V. All rights reserved.

Long-term variability of the thunderstorm and hail potential in Europe

NASA Astrophysics Data System (ADS)

Mohr, Susanna; Kunz, Michael; Speidel, Johannes; Piper, David

2016-04-01

Severe thunderstorms and associated hazardous weather events such as hail frequently cause considerable damage to buildings, crops, and automobiles, resulting in large monetary costs in many parts of Europe and the world. To relate single extreme hail events to the historic context and to estimate their return periods and possible trends related to climate change, long-term statistics of hail events are required. Due to the local-scale nature of hail and a lack of suitable observation systems, however, hailstorms are not captured reliably and comprehensively for a long period of time. In view of this fact, different proxies (indirect climate data) obtained from sounding stations and regional climate models can be used to infer the probability and intensity of thunderstorms or hailstorms. In contrast to direct observational data, such proxies are available homogeneously over a long time period. The aim of the study is to investigate the potential for severe thunderstorms and their changes over past decades. Statistical analyses of sounding data show that the convective potential over the past 20 - 30 years has significantly increased over large parts of Central Europe, making severe thunderstorms more likely. A similar picture results from analyses of weather types that are most likely associated with damaging hailstorms. These weather patterns have increased, even if only slightly but nevertheless statistically significantly, in the time period from 1971 to 2000. To improve the diagnostics of hail events in regional climate models, a logistic hail model has been developed by means of a multivariate analysis method. The model is based on a combination of appropriate hail-relevant meteorological parameters. The output of the model is a new index that estimates the potential of the atmosphere for hailstorm development, referred to as potential hail index (PHI). Applied to a high-resolved reanalysis run for Europe driven by NCEP/NCAR1, long-term changes of the PHI for 60 years (1951-2010) show large annual and multiannual variability. The trends are mostly positive in the western parts and negative to the east. However, due to the large temporal variability, the trends are not significant at most of the grid points. Furthermore, it becomes clear that the environmental conditions that favor the formation of hailstorms prevail in larger areas. This finding suggests that, despite the local-scale nature of convective storms, the ambient conditions favoring these events are mainly controlled by large-scale circulation patterns and mechanisms. This result is important to estimate the convective potential of the atmosphere in case of single events.

Hydrology and relation of selected water-quality constituents to selected physical factors in Dakota County, Minnesota, 1990-91

USGS Publications Warehouse

Almendinger, J.E.; Mitton, G.B.

1995-01-01

Selected water-quality constituents were determined in water from 5 surface-water sites and 29 wells in Dakota County, Minnesota, to search for possible relations to selected physical factors, including waste-water discharge, agricultural land, Quaternary deposits, bedrock, soil-leaching potential, and water-table depth. All surface-water samples were from the Vermillion River Basin, whose hydrologic setting was studied to determine its relation to the ground-water flow in the surrounding surficial sand aquifer. Each site was sampled from 1 to 12 times during 1990- 91. A total of 198 samples were collected; selected samples were analyzed for major inorganic ions, nutrients, and triazine content. Physical factors within the area of land assumed to be contributing water to each sampling site were determined from existing mapped or digitized sources. Nitrate concentrations in ground water were related to agricultural land and soil-leaching potential. Nitrate concentrations were large (median 13.2 milligrams per liter as nitrogen) where the percentage of agricultural land in the contributing area was large (equal to or greater than 75 percent) and where the soils had a large soil-leaching potential. Nitrate concentrations were small (median 3.2 milligrams per liter as nitrogen) where the soils had a small soil-leaching potential, despite a large percentage of agricultural land. The statistical relation was not particularly strong, however: the null hypothesis that sites with different soil-leaching potentials had the same nitrate concentrations in ground water was rejected by the Kruskal-Wallis test at only the probability P = 0.15 level. Water-table depth was not an important factor in the relation between nitrate concentrations in ground water and agricultural land. Discharge from a waste-water treatment plant provided most of the downstream loading of nitrate into the Vermillion River mainstem. Triazines were found in small concentrations (less than 2 micrograms per liter) in the Vermillion River and its tributaries. No relation was apparent between selected water-quality constituents and either Quaternary deposits or bedrock.

Fermi surfaces in Kondo insulators

NASA Astrophysics Data System (ADS)

Liu, Hsu; Hartstein, Máté; Wallace, Gregory J.; Davies, Alexander J.; Ciomaga Hatnean, Monica; Johannes, Michelle D.; Shitsevalova, Natalya; Balakrishnan, Geetha; Sebastian, Suchitra E.

2018-04-01

We report magnetic quantum oscillations measured using torque magnetisation in the Kondo insulator YbB12 and discuss the potential origin of the underlying Fermi surface. Observed quantum oscillations as well as complementary quantities such as a finite linear specific heat capacity in YbB12 exhibit similarities with the Kondo insulator SmB6, yet also crucial differences. Small heavy Fermi sections are observed in YbB12 with similarities to the neighbouring heavy fermion semimetallic Fermi surface, in contrast to large light Fermi surface sections in SmB6 which are more similar to the conduction electron Fermi surface. A rich spectrum of theoretical models is suggested to explain the origin across different Kondo insulating families of a bulk Fermi surface potentially from novel itinerant quasiparticles that couple to magnetic fields, yet do not couple to weak DC electric fields.

Cell and Particle Interactions and Aggregation During Electrophoretic Motion

NASA Technical Reports Server (NTRS)

Davis, Robert H.

2000-01-01

The objectives of this research were (i) to perform experiments for observing and quantifying electrophoretic aggregation, (ii) to develop a theoretical description to appropriately analyze and compare with the experimental results, (iii) to study the combined effects of electrophoretic and gravitational aggregation of large particles, and the combined effects of electrophoretic and Brownian aggregation of small particles, and (iv) to perform a preliminary design of a potential future flight experiment involving electrophoretic aggregation. Electrophoresis refers to the motion of charged particles, droplets or molecules in response to an applied electric field. Electrophoresis is commonly used for analysis and separation of biological particles or molecules. When particles have different surface charge densities or potentials, they will migrate at different velocities in an electric field. This differential migration leads to the possibility that they will collide and aggregate, thereby preventing separation.

Positive Affect Processing and Joint Attention in Infants at High Risk for Autism: An Exploratory Study

PubMed Central

Key, Alexandra P.; Ibanez, Lisa V.; Henderson, Heather A.; Warren, Zachary; Messinger, Daniel S.; Stone, Wendy L.

2014-01-01

Few behavioral indices of risk for autism spectrum disorders (ASD) are present before 12 months, and potential biomarkers remain largely unexamined. This prospective study of infant siblings of children with ASD (n=16) and low-risk comparison infants (n= 15) examined group differences in event-related potentials (ERPs) indexing processing of facial positive affect (N290/P400, Nc) at 9 months and their relation to joint attention at 15 months. Group differences were most pronounced for subtle facial expressions, in that the low-risk group exhibited relatively longer processing (P400 latency) and greater attention resource allocation (Nc amplitude). Exploratory analyses found associations between ERP responses and later joint attention, suggesting that attention to positive affect cues may support the development of other social competencies. PMID:25056131

Geospatial Augmented Reality for the interactive exploitation of large-scale walkable orthoimage maps in museums

NASA Astrophysics Data System (ADS)

Wüest, Robert; Nebiker, Stephan

2018-05-01

In this paper we present an app framework for augmenting large-scale walkable maps and orthoimages in museums or public spaces using standard smartphones and tablets. We first introduce a novel approach for using huge orthoimage mosaic floor prints covering several hundred square meters as natural Augmented Reality (AR) markers. We then present a new app architecture and subsequent tests in the Swissarena of the Swiss National Transport Museum in Lucerne demonstrating the capabilities of accurately tracking and augmenting different map topics, including dynamic 3d data such as live air traffic. The resulting prototype was tested with everyday visitors of the museum to get feedback on the usability of the AR app and to identify pitfalls when using AR in the context of a potentially crowded museum. The prototype is to be rolled out to the public after successful testing and optimization of the app. We were able to show that AR apps on standard smartphone devices can dramatically enhance the interactive use of large-scale maps for different purposes such as education or serious gaming in a museum context.

Genetic basis of climatic adaptation in scots pine by bayesian quantitative trait locus analysis.

PubMed Central

Hurme, P; Sillanpää, M J; Arjas, E; Repo, T; Savolainen, O

2000-01-01

We examined the genetic basis of large adaptive differences in timing of bud set and frost hardiness between natural populations of Scots pine. As a mapping population, we considered an "open-pollinated backcross" progeny by collecting seeds of a single F(1) tree (cross between trees from southern and northern Finland) growing in southern Finland. Due to the special features of the design (no marker information available on grandparents or the father), we applied a Bayesian quantitative trait locus (QTL) mapping method developed previously for outcrossed offspring. We found four potential QTL for timing of bud set and seven for frost hardiness. Bayesian analyses detected more QTL than ANOVA for frost hardiness, but the opposite was true for bud set. These QTL included alleles with rather large effects, and additionally smaller QTL were supported. The largest QTL for bud set date accounted for about a fourth of the mean difference between populations. Thus, natural selection during adaptation has resulted in selection of at least some alleles of rather large effect. PMID:11063704

Prospects, recent advancements and challenges of different wastewater streams for microalgal cultivation.

PubMed

Guldhe, Abhishek; Kumari, Sheena; Ramanna, Luveshan; Ramsundar, Prathana; Singh, Poonam; Rawat, Ismail; Bux, Faizal

2017-12-01

Microalgae are recognized as one of the most powerful biotechnology platforms for many value added products including biofuels, bioactive compounds, animal and aquaculture feed etc. However, large scale production of microalgal biomass poses challenges due to the requirements of large amounts of water and nutrients for cultivation. Using wastewater for microalgal cultivation has emerged as a potential cost effective strategy for large scale microalgal biomass production. This approach also offers an efficient means to remove nutrients and metals from wastewater making wastewater treatment sustainable and energy efficient. Therefore, much research has been conducted in the recent years on utilizing various wastewater streams for microalgae cultivation. This review identifies and discusses the opportunities and challenges of different wastewater streams for microalgal cultivation. Many alternative routes for microalgal cultivation have been proposed to tackle some of the challenges that occur during microalgal cultivation in wastewater such as nutrient deficiency, substrate inhibition, toxicity etc. Scope and challenges of microalgal biomass grown on wastewater for various applications are also discussed along with the biorefinery approach. Copyright © 2017 Elsevier Ltd. All rights reserved.

Peptide arrays on cellulose support: SPOT synthesis, a time and cost efficient method for synthesis of large numbers of peptides in a parallel and addressable fashion.

PubMed

Hilpert, Kai; Winkler, Dirk F H; Hancock, Robert E W

2007-01-01

Peptide synthesis on cellulose using SPOT technology allows the parallel synthesis of large numbers of addressable peptides in small amounts. In addition, the cost per peptide is less than 1% of peptides synthesized conventionally on resin. The SPOT method follows standard fluorenyl-methoxy-carbonyl chemistry on conventional cellulose sheets, and can utilize more than 600 different building blocks. The procedure involves three phases: preparation of the cellulose membrane, stepwise coupling of the amino acids and cleavage of the side-chain protection groups. If necessary, peptides can be cleaved from the membrane for assays performed using soluble peptides. These features make this method an excellent tool for screening large numbers of peptides for many different purposes. Potential applications range from simple binding assays, to more sophisticated enzyme assays and studies with living microbes or cells. The time required to complete the protocol depends on the number and length of the peptides. For example, 400 9-mer peptides can be synthesized within 6 days.

Separate collection of household food waste for anaerobic degradation - Comparison of different techniques from a systems perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernstad, A., E-mail: Anna.bernstad@chemeng.lth.se; Cour Jansen, J. la

Highlight: Black-Right-Pointing-Pointer Four modern and innovative systems for household food waste collection are compared. Black-Right-Pointing-Pointer Direct emissions and resource use were based on full-scale data. Black-Right-Pointing-Pointer Conservation of nutrients/energy content over the system was considered. Black-Right-Pointing-Pointer Systems with high energy/nutrient recovery are most environmentally beneficial. - Abstract: Four systems for household food waste collection are compared in relation the environmental impact categories eutrophication potential, acidification potential, global warming potential as well as energy use. Also, a hotspot analysis is performed in order to suggest improvements in each of the compared collection systems. Separate collection of household food waste in papermore » bags (with and without drying prior to collection) with use of kitchen grinders and with use of vacuum system in kitchen sinks were compared. In all cases, food waste was used for anaerobic digestion with energy and nutrient recovery in all cases. Compared systems all resulted in net avoidance of assessed environmental impact categories; eutrophication potential (-0.1 to -2.4 kg NO{sub 3}{sup -}eq/ton food waste), acidification potential (-0.4 to -1.0 kg SO{sub 2}{sup -}eq/ton food waste), global warming potential (-790 to -960 kg CO{sub 2}{sup -}eq/ton food waste) and primary energy use (-1.7 to -3.6 GJ/ton food waste). Collection with vacuum system results in the largest net avoidance of primary energy use, while disposal of food waste in paper bags for decentralized drying before collection result in a larger net avoidance of global warming, eutrophication and acidification. However, both these systems not have been taken into use in large scale systems yet and further investigations are needed in order to confirm the outcomes from the comparison. Ranking of scenarios differ largely if considering only emissions in the foreground system, indicating the importance of taking also downstream emissions into consideration when comparing different collection systems. The hot spot identification shows that losses of organic matter in mechanical pretreatment as well as tank connected food waste disposal systems and energy in drying and vacuum systems reply to the largest impact on the results in each system respectively.« less

Spatiotemporal Fractionation Schemes for Irradiating Large Cerebral Arteriovenous Malformations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Unkelbach, Jan, E-mail: junkelbach@mgh.harvard.edu; Bussière, Marc R.; Chapman, Paul H.

2016-07-01

Purpose: To optimally exploit fractionation effects in the context of radiosurgery treatments of large cerebral arteriovenous malformations (AVMs). In current practice, fractionated treatments divide the dose evenly into several fractions, which generally leads to low obliteration rates. In this work, we investigate the potential benefit of delivering distinct dose distributions in different fractions. Methods and Materials: Five patients with large cerebral AVMs were reviewed and replanned for intensity modulated arc therapy delivered with conventional photon beams. Treatment plans allowing for different dose distributions in all fractions were obtained by performing treatment plan optimization based on the cumulative biologically effective dosemore » delivered at the end of treatment. Results: We show that distinct treatment plans can be designed for different fractions, such that high single-fraction doses are delivered to complementary parts of the AVM. All plans create a similar dose bath in the surrounding normal brain and thereby exploit the fractionation effect. This partial hypofractionation in the AVM along with fractionation in normal brain achieves a net improvement of the therapeutic ratio. We show that a biological dose reduction of approximately 10% in the healthy brain can be achieved compared with reference treatment schedules that deliver the same dose distribution in all fractions. Conclusions: Boosting complementary parts of the target volume in different fractions may provide a therapeutic advantage in fractionated radiosurgery treatments of large cerebral AVMs. The strategy allows for a mean dose reduction in normal brain that may be valuable for a patient population with an otherwise normal life expectancy.« less

Charcoal addition to soils in NE England: a carbon sink with environmental co-benefits?

PubMed

Bell, M J; Worrall, F

2011-04-01

Interest in the application of biochar (charcoal produced during the pyrolysis of biomass) to agricultural land is increasing across the world, recognised as a potential way to capture and store atmospheric carbon. Its interest is heightened by its potential co-benefits for soil quality and fertility. The majority of research has however been undertaken in tropical rather than temperate regions. This study assessed the potential for lump-wood charcoal addition (as a substitute for biochar) to soil types which are typically under arable and forest land-use in North East England. The study was undertaken over a 28 week period and found: i) No significant difference in net ecosystem respiration (NER) between soils containing charcoal and those without, other than in week 1 of the trial. ii) A significantly higher dissolved organic carbon (DOC) flux from soils containing large amounts of charcoal than from those untreated, when planted with ryegrass. iii) That when increased respiration or DOC loss did occur, neither was sufficiently large to alter the carbon sink benefits of charcoal application. iv) That charcoal incorporation resulted in a significantly lower nitrate flux in soil leachate from mineral soils. v) That charcoal incorporation caused significant increases in soil pH, from 6.98 to 7.22 on bare arable soils when 87,500 kg charcoal/ha was applied. Consideration of both the carbon sink and environmental benefits observed here suggests that charcoal application to temperate soils typical of North East England should be considered as a method of carbon sequestration. Before large scale land application is encouraged, further large scale trials should be undertaken to confirm the positive results of this research. Copyright © 2011 Elsevier B.V. All rights reserved.

Separation of plutonium from lanthanum by electrolysis in LiCl KCl onto molten bismuth electrode

NASA Astrophysics Data System (ADS)

Serp, J.; Lefebvre, P.; Malmbeck, R.; Rebizant, J.; Vallet, P.; Glatz, J.-P.

2005-04-01

This work presents a study on the electroseparation of plutonium from lanthanum using molten bismuth electrodes in LiCl-KCl eutectic at 733 K. The reduction potentials of Pu3+ and La3+ ions were measured on a Bi thin film electrode using cyclic voltammetry (CV). A difference between the peak potentials for the formation of PuBi2 and LaBi2 of approximately 100 mV was found. Separation tests were then carried out using different current densities and salt phase compositions between a plutonium rod anode and an unstirred molten Bi cathode in order to evaluate the efficiency of an electrolytic separation process. At a current density of 12 mA/cm2/wt% (Pu3+), only Pu3+ ions are reduced into the molten Bi electrode, leaving La3+ ions in the salt melt. Similar results were found at two different Pu/La concentration ratios ([Pu]/[La] = 4 and 10). At a current density of 26 mA/cm2/wt% (Pu3+), co-reduction of Pu and La was observed as expected by the large negative potential of the Bi cathode during the separation test.

[Construction and evaluation of ecological network in Poyang Lake Eco-economic Zone, China.

PubMed

Chen, Xiao Ping; Chen, Wen Bo

2016-05-01

Large-scale ecological patches play an important role in regional biodiversity conservation. However, with the rapid progress of China's urbanization, human disturbance on the environment is becoming stronger. Large-scale ecological patches will degrade not only in quantity, but also in quality, threatening the connections among them due to isolation and seriously affecting the biodiversity protection. Taking Poyang Lake Eco-economic Zone as a case, this paper established the potential ecological corridors by minimum cost model and GIS technique taking the impacts of landscape types, slope and human disturbance into consideration. Then, based on gravity quantitative model, we analyzed the intensity of ecological interactions between patches, and the potential ecological corridors were divided into two classes for sake of protection. Finally, the important ecological nodes and breaking points were identified, and the structure of the potential ecological network was analyzed. The results showed that forest and cropland were the main landscape types of ecological corridor composition, interaction between ecological patches differed obviously and the structure of the composed regional ecological network was complex with high connectivity and closure. It might provide a scientific basis for the protection of biodiversity and ecological network optimization in Poyang Lake Eco-economic Zone.

A comparison of dispersing media for various engineered carbon nanoparticles

PubMed Central

Buford, Mary C; Hamilton, Raymond F; Holian, Andrij

2007-01-01

Background With the increased manufacture and use of carbon nanoparticles (CNP) there has been increasing concern about the potential toxicity of fugitive CNP in the workplace and ambient environment. To address this matter a number of investigators have conducted in vitro and in vivo toxicity assessments. However, a variety of different approaches for suspension of these particles (culture media, Tween 80, dimethyl sulfoxide, phosphate-buffered saline, fetal calf serum, and others), and different sources of materials have generated potentially conflicting outcomes. The quality of the dispersion of nanoparticles is very dependent on the medium used to suspend them, and this then will most likely affect the biological outcomes. Results In this work, the distributions of different CNP (sources and types) have been characterized in various media. Furthermore, the outcome of instilling the different agglomerates, or size distributions, was examined in mouse lungs after one and seven days. Our results demonstrated that CNP suspended in serum produced particle suspensions with the fewest large agglomerates, and the most uniform distribution in mouse lungs. In addition, no apparent clearance of instilled CNP took place from lungs even after seven days. Conclusion This work demonstrates that CNP agglomerates are present in all dispersing vehicles to some degree. The vehicle that contains some protein, lipid or protein/lipid component disperses the CNP best, producing fewer large CNP agglomerates. In contrast, vehicles absent of lipid and protein produce the largest CNP agglomerates. The source of the CNP is also a factor in the degree of particle agglomeration within the same vehicle. PMID:17655771

A comparison of in situ measurements of vector-E and - vector-V x vector-B from Dynamics Explorer 2

NASA Technical Reports Server (NTRS)

Hanson, W. B.; Coley, W. R.; Heelis, R. A.; Maynard, N. C.; Aggson, T. L.

1993-01-01

Dynamics Explorer-2 provided the first opportunity to make a direct comparison of in situ measurements of the high-latitude convection electric field by two distinctly different techniques. The vector electric field instrument (VEFI) used antennae to measure the intrinsic electric fields and the ion drift meter (IDM) and retarding potential analyzer (RPA) measured the ion drift velocity vector, from which the convection electric field can be deduced. The data from three orbits having large electric fields at high latitude are presented, one at high, one at medium, and one at low altitudes. The general agreement between the two measurements of electric field is very good, with typical differences at high latitudes of the order of a few millivolts per meter, but there are some regions where the particle fluxes are extremely large (e.g., the cusp) and the disagreement is worse, probably because of IDM difficulties. The auroral zone potential patterns derived from the two devices are in excellent agreement for two of the cases, but not in the third, where bad attitude data may be the problem. At low latitudes there are persistent differences in the measurements of a few millivolts per meter, though these differences are quite constant from orbit to orbit. This problem seems to arise from some shortcoming in the VEFI measurments. Overall, however, these measurements confirm the concept of `frozen-in' plasma that drifts with velocity vector-E x vector-B/B(exp 2) within the measurement errors of the two techniques.

Two-machine flow shop scheduling integrated with preventive maintenance planning

NASA Astrophysics Data System (ADS)

Wang, Shijin; Liu, Ming

2016-02-01

This paper investigates an integrated optimisation problem of production scheduling and preventive maintenance (PM) in a two-machine flow shop with time to failure of each machine subject to a Weibull probability distribution. The objective is to find the optimal job sequence and the optimal PM decisions before each job such that the expected makespan is minimised. To investigate the value of integrated scheduling solution, computational experiments on small-scale problems with different configurations are conducted with total enumeration method, and the results are compared with those of scheduling without maintenance but with machine degradation, and individual job scheduling combined with independent PM planning. Then, for large-scale problems, four genetic algorithm (GA) based heuristics are proposed. The numerical results with several large problem sizes and different configurations indicate the potential benefits of integrated scheduling solution and the results also show that proposed GA-based heuristics are efficient for the integrated problem.

Climate limits across space and time on European forest structure

NASA Astrophysics Data System (ADS)

Moreno, A. L. S.; Neumann, M.; Hasenauer, H.

2017-12-01

The impact climate has on forests has been extensively studied. However, the large scale effect climate has on forest structures, such as average diameters, heights and basal area are understudied in a spatially explicit manner. The limits, tipping points and thresholds that climate places on forest structures dictate the services a forest may provide, the vulnerability of a forest to mortality and the potential value of the timber there within. The majority of current research either investigates climate impacts on forest pools and fluxes, on a tree physiological scale or on case studies that are used to extrapolate results and potential impacts. A spatially explicit study on how climate affects forest structure over a large region would give valuable information to stakeholders who are more concerned with ecosystem services that cannot be described by pools and fluxes but require spatially explicit information - such as biodiversity, habitat suitability, and market values. In this study, we quantified the limits that climate (maximum, minimum temperature and precipitation) places on 3 forest structures, diameter at breast height, height, and basal area throughout Europe. Our results show clear climatic zones of high and low upper limits for each forest structure variable studied. We also spatially analyzed how climate restricts the potential bio-physical upper limits and creates tipping points of each forest structure variable and which climate factors are most limiting. Further, we demonstrated how the climate change has affected 8 individual forests across Europe and then the continent as a whole. We find that diameter, height and basal area are limited by climate in different ways and that areas may have high upper limits in one structure and low upper limits in another limitted by different climate variables. We also found that even though individual forests may have increased their potential upper limit forest structure values, European forests as a whole have lost, on average, 5.0%, 1.7% and 6.5% in potential mean forest diameter, height and basal area, respectively.

Further Refinement of the LEWICE SLD Model

NASA Technical Reports Server (NTRS)

Wright, William B.

2006-01-01

A research project is underway at NASA Glenn Research Center to produce computer software that can accurately predict ice growth for any meteorological conditions for any aircraft surface. This report will present results from version 3.2 of this software, which is called LEWICE. This version differs from previous releases in that it incorporates additional thermal analysis capabilities, a pneumatic boot model, interfaces to external computational fluid dynamics (CFD) flow solvers and has an empirical model for the supercooled large droplet (SLD) regime. An extensive comparison against the database of ice shapes and collection efficiencies that have been generated in the NASA Glenn Icing Research Tunnel (IRT) has also been performed. The complete set of data used for this comparison will eventually be available in a contractor report. This paper will show the differences in collection efficiency and ice shape between LEWICE 3.2 and experimental data. This report will first describe the LEWICE 3.2 SLD model. A semi-empirical approach was used to incorporate first order physical effects of large droplet phenomena into icing software. Comparisons are then made to every two-dimensional case in the water collection database and the ice shape database. Each collection efficiency condition was run using the following four assumptions: 1) potential flow, no splashing; 2) potential flow, with splashing; 3) Navior-Stokes, no splashing; 4) Navi r-Stokes, with splashing. All cases were run with 21 bin drop size distributions and a lift correction (angle of attack adjustment). Quantitative comparisons are shown for impingement limit, maximum water catch, and total collection efficiency. Due to the large number of ice shape cases, comprehensive comparisons were limited to potential flow cases with and without splashing. Quantitative comparisons are shown for horn height, horn angle, icing limit, area, and leading edge thickness. The results show that the predicted results for both ice shape and water collection are within the accuracy limits of the experimental data for the majority of cases.

Gene expression profiles of changes underlying different-sized human rotator cuff tendon tears.

PubMed

Chaudhury, Salma; Xia, Zhidao; Thakkar, Dipti; Hakimi, Osnat; Carr, Andrew J

2016-10-01

Progressive cellular and extracellular matrix (ECM) changes related to age and disease severity have been demonstrated in rotator cuff tendon tears. Larger rotator cuff tears demonstrate structural abnormalities that potentially adversely influence healing potential. This study aimed to gain greater insight into the relationship of pathologic changes to tear size by analyzing gene expression profiles from normal rotator cuff tendons, small rotator cuff tears, and large rotator cuff tears. We analyzed gene expression profiles of 28 human rotator cuff tendons using microarrays representing the entire genome; 11 large and 5 small torn rotator cuff tendon specimens were obtained intraoperatively from tear edges, which we compared with 12 age-matched normal controls. We performed real-time polymerase chain reaction and immunohistochemistry for validation. Torn rotator cuff tendons demonstrated upregulation of a number of key genes, such as matrix metalloproteinase 3, 10, 12, 13, 15, 21, and 25; a disintegrin and metalloproteinase (ADAM) 12, 15, and 22; and aggrecan. Amyloid was downregulated in all tears. Small tears displayed upregulation of bone morphogenetic protein 5. Chemokines and cytokines that may play a role in chemotaxis were altered; interleukins 3, 10, 13, and 15 were upregulated in tears, whereas interleukins 1, 8, 11, 18, and 27 were downregulated. The gene expression profiles of normal controls and small and large rotator cuff tear groups differ significantly. Extracellular matrix remodeling genes were found to contribute to rotator cuff tear pathogenesis. Rotator cuff tears displayed upregulation of a number of matrix metalloproteinase (3, 10, 12, 13, 15, 21, and 25), a disintegrin and metalloproteinase (ADAM 12, 15, and 22) genes, and downregulation of some interleukins (1, 8, and 27), which play important roles in chemotaxis. These gene products may potentially have a role as biomarkers of failure of healing or therapeutic targets to improve tendon healing. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

New Evidence on Self-Affirmation Effects and Theorized Sources of Heterogeneity from Large-Scale Replications

PubMed Central

Hanselman, Paul; Rozek, Christopher S.; Grigg, Jeffrey; Borman, Geoffrey D.

2016-01-01

Brief, targeted self-affirmation writing exercises have recently been offered as a way to reduce racial achievement gaps, but evidence about their effects in educational settings is mixed, leaving ambiguity about the likely benefits of these strategies if implemented broadly. A key limitation in interpreting these mixed results is that they come from studies conducted by different research teams with different procedures in different settings; it is therefore impossible to isolate whether different effects are the result of theorized heterogeneity, unidentified moderators, or idiosyncratic features of the different studies. We addressed this limitation by conducting a well-powered replication of self-affirmation in a setting where a previous large-scale field experiment demonstrated significant positive impacts, using the same procedures. We found no evidence of effects in this replication study and estimates were precise enough to reject benefits larger than an effect size of 0.10. These null effects were significantly different from persistent benefits in the prior study in the same setting, and extensive testing revealed that currently theorized moderators of self-affirmation effects could not explain the difference. These results highlight the potential fragility of self-affirmation in educational settings when implemented widely and the need for new theory, measures, and evidence about the necessary conditions for self-affirmation success. PMID:28450753

Dressed ion theory of size-asymmetric electrolytes: effective ionic charges and the decay length of screened Coulomb potential and pair correlations.

PubMed

Forsberg, Björn; Ulander, Johan; Kjellander, Roland

2005-02-08

The effects of ionic size asymmetry on long-range electrostatic interactions in electrolyte solutions are investigated within the primitive model. Using the formalism of dressed ion theory we analyze correlation functions from Monte Carlo simulations and the hypernetted chain approximation for size asymmetric 1:1 electrolytes. We obtain decay lengths of the screened Coulomb potential, effective charges of ions, and effective permittivity of the solution. It is found that the variation of these quantities with the degree of size asymmetry depends in a quite intricate manner on the interplay between the electrostatic coupling and excluded volume effects. In most cases the magnitude of the effective charge of the small ion species is larger than that of the large species; the difference increases with increasing size asymmetry. The effective charges of both species are larger (in absolute value) than the bare ionic charge, except for high asymmetry where the effective charge of the large ions can become smaller than the bare charge.

Dendritic Na+ spikes enable cortical input to drive action potential output from hippocampal CA2 pyramidal neurons

PubMed Central

Sun, Qian; Srinivas, Kalyan V; Sotayo, Alaba; Siegelbaum, Steven A

2014-01-01

Synaptic inputs from different brain areas are often targeted to distinct regions of neuronal dendritic arbors. Inputs to proximal dendrites usually produce large somatic EPSPs that efficiently trigger action potential (AP) output, whereas inputs to distal dendrites are greatly attenuated and may largely modulate AP output. In contrast to most other cortical and hippocampal neurons, hippocampal CA2 pyramidal neurons show unusually strong excitation by their distal dendritic inputs from entorhinal cortex (EC). In this study, we demonstrate that the ability of these EC inputs to drive CA2 AP output requires the firing of local dendritic Na+ spikes. Furthermore, we find that CA2 dendritic geometry contributes to the efficient coupling of dendritic Na+ spikes to AP output. These results provide a striking example of how dendritic spikes enable direct cortical inputs to overcome unfavorable distal synaptic locale to trigger axonal AP output and thereby enable efficient cortico-hippocampal information flow. DOI: http://dx.doi.org/10.7554/eLife.04551.001 PMID:25390033

SAR-based sea traffic monitoring: a reliable approach for maritime surveillance

NASA Astrophysics Data System (ADS)

Renga, Alfredo; Graziano, Maria D.; D'Errico, M.; Moccia, A.; Cecchini, A.

2011-11-01

Maritime surveillance problems are drawing the attention of multiple institutional actors. National and international security agencies are interested in matters like maritime traffic security, maritime pollution control, monitoring migration flows and detection of illegal fishing activities. Satellite imaging is a good way to identify ships but, characterized by large swaths, it is likely that the imaged scenes contain a large number of ships, with the vast majority, hopefully, performing legal activities. Therefore, the imaging system needs a supporting system which identifies legal ships and limits the number of potential alarms to be further monitored by patrol boats or aircrafts. In this framework, spaceborne Synthetic Aperture Radar (SAR) sensors, terrestrial AIS and the ongoing satellite AIS systems can represent a great potential synergy for maritime security. Starting from this idea the paper develops different designs for an AIS constellation able to reduce the time lag between SAR image and AIS data acquisition. An analysis of SAR-based ship detection algorithms is also reported and candidate algorithms identified.

Diffusion of Brownian particles in a tilted periodic potential under the influence of an external Ornstein-Uhlenbeck noise

NASA Astrophysics Data System (ADS)

Bai, Zhan-Wu; Zhang, Wei

2018-01-01

The diffusion behaviors of Brownian particles in a tilted periodic potential under the influence of an internal white noise and an external Ornstein-Uhlenbeck noise are investigated through numerical simulation. In contrast to the case when the bias force is smaller or absent, the diffusion coefficient exhibits a nonmonotonic dependence on the correlation time of the external noise when bias force is large. A mechanism different from locked-to-running transition theory is presented for the diffusion enhancement by a bias force in intermediate to large damping. In the underdamped regime and the presence of external noise, the diffusion coefficient is a monotonically decreasing function of low temperature rather than a nonmonotonic function when external noise is absent. The diffusive process undergoes four regimes when bias force approaches but is less than its critical value and noises intensities are small. These behaviors can be attributed to the locked-to-running transition of particles.

Disgust and Obsessive Beliefs in Contamination-related OCD

PubMed Central

Cisler, Josh M.; Brady, Robert E.; Olatunji, Bunmi O.; Lohr, Jeffrey M.

2010-01-01

A large body of evidence suggests that disgust is an important affective process underlying contamination fear. An independent line of research demonstrates that obsessive beliefs, particularly overestimations of threat, are also an important cognitive process underlying contamination fear. The present study attempts to integrate these two lines of research by testing whether obsessive beliefs potentiate the influence of disgust propensity on contamination fear. The interaction between disgust propensity and obsessive beliefs was tested in two large non-clinical samples (N = 252 in Study 1; N = 308 in Study 2) using two different self-report measures of contamination fear. Regression analyses supported the hypotheses in both samples. The interaction remained significant when controlling for negative affect. The results are hypothesized to suggest that contamination fear results, at least partly, from obsessive beliefs about the contamination-based appraisals that accompany heightened disgust responding. These results complement previous affective-driven explanations of the role of disgust in contamination fear by suggesting cognitive factors that similarly potentiate disgust’s role in contamination fear. PMID:20877585

Outdoor environmental assessment of attention promoting settings for preschool children.

PubMed

Mårtensson, F; Boldemann, C; Söderström, M; Blennow, M; Englund, J-E; Grahn, P

2009-12-01

The restorative potential of green outdoor environments for children in preschool settings was investigated by measuring the attention of children playing in settings with different environmental features. Eleven preschools with outdoor environments typical for the Stockholm area were assessed using the outdoor play environment categories (OPEC) and the fraction of visible sky from play structures (sky view factor), and 198 children, aged 4.5-6.5 years, were rated by the staff for inattentive, hyperactive and impulsive behaviors with the ECADDES tool. Children playing in large and integrated outdoor areas containing large areas of trees, shrubbery and a hilly terrain showed less often behaviors of inattention (p<.05). The choice of tool for assessment of attention is discussed in relation to outdoor stay and play characteristics in Swedish preschool settings. The results indicate that the restorative potential of green outdoor environments applies also to preschool children and that environmental assessment tools as OPEC can be useful when to locate and develop health-promoting land adjacent to preschools.

Diffusion bonded boron/aluminum spar-shell fan blade

NASA Technical Reports Server (NTRS)

Carlson, C. E. K.; Cutler, J. L.; Fisher, W. J.; Memmott, J. V. W.

1980-01-01

Design and process development tasks intended to demonstrate composite blade application in large high by-pass ratio turbofan engines are described. Studies on a 3.0 aspect radio space and shell construction fan blade indicate a potential weight savings for a first stage fan rotor of 39% when a hollow titanium spar is employed. An alternate design which featured substantial blade internal volume filled with titanium honeycomb inserts achieved a 14% potential weight savings over the B/M rotor system. This second configuration requires a smaller development effort and entails less risk to translate a design into a successful product. The feasibility of metal joining large subsonic spar and shell fan blades was demonstrated. Initial aluminum alloy screening indicates a distinct preference for AA6061 aluminum alloy for use as a joint material. The simulated airfoil pressings established the necessity of rigid air surfaces when joining materials of different compressive rigidities. The two aluminum alloy matrix choices both were successfully formed into blade shells.

Networks with fourfold connectivity in two dimensions.

PubMed

Tessier, Frédéric; Boal, David H; Discher, Dennis E

2003-01-01

The elastic properties of planar, C4-symmetric networks under stress and at nonzero temperature are determined by simulation and mean field approximations. Attached at fourfold coordinated junction vertices, the networks are self-avoiding in that their elements (or bonds) may not intersect each other. Two different models are considered for the potential energy of the elements: either Hooke's law springs or flexible tethers (square well potential). For certain ranges of stress and temperature, the properties of the networks are captured by one of several models: at large tensions, the networks behave like a uniform system of square plaquettes, while at large compressions or high temperatures, they display many characteristics of an ideal gas. Under less severe conditions, mean field models with more general shapes (parallelograms) reproduce many essential features of both networks. Lastly, the spring network expands without limit at a two-dimensional tension equal to the force constant of the spring; however, it does not appear to collapse under compression, except at zero temperature.

Marine actinobacteria: an important source of bioactive natural products.

PubMed

Manivasagan, Panchanathan; Kang, Kyong-Hwa; Sivakumar, Kannan; Li-Chan, Eunice C Y; Oh, Hyun-Myung; Kim, Se-Kwon

2014-07-01

Marine environment is largely an untapped source for deriving actinobacteria, having potential to produce novel, bioactive natural products. Actinobacteria are the prolific producers of pharmaceutically active secondary metabolites, accounting for about 70% of the naturally derived compounds that are currently in clinical use. Among the various actinobacterial genera, Actinomadura, Actinoplanes, Amycolatopsis, Marinispora, Micromonospora, Nocardiopsis, Saccharopolyspora, Salinispora, Streptomyces and Verrucosispora are the major potential producers of commercially important bioactive natural products. In this respect, Streptomyces ranks first with a large number of bioactive natural products. Marine actinobacteria are unique enhancing quite different biological properties including antimicrobial, anticancer, antiviral, insecticidal and enzyme inhibitory activities. They have attracted global in the last ten years for their ability to produce pharmaceutically active compounds. In this review, we have focused attention on the bioactive natural products isolated from marine actinobacteria, possessing unique chemical structures that may form the basis for synthesis of novel drugs that could be used to combat resistant pathogenic microorganisms. Copyright © 2014 Elsevier B.V. All rights reserved.

Predicting fat, lean and the weights of primal cuts for growing pigs of different genotypes and sexes using computed tomography.

PubMed

Carabús, A; Sainz, R D; Oltjen, J W; Gispert, M; Font-i-Furnols, M

2015-03-01

The aim of the present study was to find single equations to predict the amounts of fat, lean, and the weights of the primal cuts (ham, loin, belly, and shoulder) as well as ham composition of pigs from 30 to 120 kg BW of different genotypes (GEN; Exp. 1) and sexual conditions (SEX; Exp. 2). Two types of regression equations, taking into account different work situations, were developed: 1) research applications, using computed tomography (CT) parameters, and 2) potential on-farm applications, which could be obtained using easily accessible equipment. Two data sets were used: Exp. 1 included 90 gilts from 3 different GEN: 30 Duroc × (Landrace × Large White), 30 Pietrain × (Landrace × Large White), and 30 Landrace × Large White, and Exp. 2 included 92 Pietrain × (Landrace × Duroc) pigs of different SEX: 24 each of females, entire males, castrated males, and 20 immunocastrated males. Pigs were fully CT scanned in vivo at 30, 70, 100, and 120 kg BW. A subsample of pigs of each GEN ( = 5) or SEX ( = 4) were slaughtered at 30, 70, and 100 kg BW, and all remaining pigs were slaughtered after weighing and scanning at 120 kg BW. For all the slaughtered pigs, the 4 main cuts were fully (GEN) or partially dissected (SEX). CT images were analyzed and used to predict the lean and fat contents as well as the weights of the primal cuts and the composition of the ham. Total amounts of fat and lean for both populations were predicted with high levels of accuracy ( = 0.994 and 0.993, respectively) and proportions of random error for GEN and SEX effects (0.998 and 0.946 for the fat and 0.997 and 0.836 for the lean predictions, respectively). Moreover, the composition of ham (fat, lean, and bone) was very well predicted with high proportions (> 80%) of random error for GEN and SEX effect using CT and potential on-farm predictors.

The temperature of primary melts and mantle sources of komatiites, OIBs, MORBs and LIPs

NASA Astrophysics Data System (ADS)

Sobolev, Alexander

2015-04-01

There is general agreement that the convecting mantle, although mostly peridotitic in composition, is compositionally and thermally heterogeneous on different spatial scales. The amount, sizes, temperatures and compositions of these heterogeneities significantly affect mantle dynamics because they may diverge greatly from dominant peridotites in their density and fusibility. Differences in potential temperature and composition of mantle domains affect magma production and cannot be easily distinguished from each other. This has led to radically different interpretations of the melting anomalies that produce ocean-island basalts, large igneous provinces and komatiites: most scientists believe that they originate as hot, deep-sourced mantle plumes; but a small though influential group (e.g. Anderson 2005, Foulger, 2010) propose that they derive from high proportions of easily fusible recycled or delaminated crust, or in the case of komatiites contain large amount of H2O (e.g. Grove & Parman, 2004). The way to resolve this ambiguity is an independent estimation of temperature and composition of mantle sources of various types of magma. In this paper I report application of newly developed olivine-spinel-melt geothermometers based on partition of Al, Cr, Sc and Y for different primitive lavas from mid-ocean ridges, ocean-island basalts, large igneous provinces and komatiites. The results suggest significant variations of crystallization temperature for the same Fo of high magnesium olivines of different types of mantle-derived magmas: from the lowest (down to 1220 degree C) for MORB to the highest (up to over 1500 degree C) for komatiites and Siberian meimechites. These results match predictions from Fe-Mg olivine-melt equilibrium and confirm the relatively low temperature of the mantle source of MORB and higher temperatures in the mantle plumes that produce the OIB of Iceland, Hawaii, Gorgona, Archean komatiites and several LIPs (e.g Siberian and NAMP). The established liquidus temperatures and compositions of primary melts allow estimating potential temperatures and compositions of their mantle sources. The results strongly confirm mantle plume theory and presence of variable amounts of recycled crustal material in the mantle sources. This study has been founded by Russian Science Foundation grant 14-17-00491.

Wetlands as large-scale nature-based solutions: status and future challenges for research and management

NASA Astrophysics Data System (ADS)

Thorslund, Josefin; Jarsjö, Jerker; Destouni, Georgia

2017-04-01

Wetlands are often considered as nature-based solutions that can provide a multitude of services of great social, economic and environmental value to humankind. The services may include recreation, greenhouse gas sequestration, contaminant retention, coastal protection, groundwater level and soil moisture regulation, flood regulation and biodiversity support. Changes in land-use, water use and climate can all impact wetland functions and occur at scales extending well beyond the local scale of an individual wetland. However, in practical applications, management decisions usually regard and focus on individual wetland sites and local conditions. To understand the potential usefulness and services of wetlands as larger-scale nature-based solutions, e.g. for mitigating negative impacts from large-scale change pressures, one needs to understand the combined function multiple wetlands at the relevant large scales. We here systematically investigate if and to what extent research so far has addressed the large-scale dynamics of landscape systems with multiple wetlands, which are likely to be relevant for understanding impacts of regional to global change. Our investigation regards key changes and impacts of relevance for nature-based solutions, such as large-scale nutrient and pollution retention, flow regulation and coastal protection. Although such large-scale knowledge is still limited, evidence suggests that the aggregated functions and effects of multiple wetlands in the landscape can differ considerably from those observed at individual wetlands. Such scale differences may have important implications for wetland function-effect predictability and management under large-scale change pressures and impacts, such as those of climate change.

Global bending quantum number and the absence of monodromy in the HCN{r_reversible}CNH molecule

DOE Office of Scientific and Technical Information (OSTI.GOV)

Efstathiou, K.; Sadovskii, D.A.; Joyeux, M.

We introduce and analyze a model system based on a deformation of a spherical pendulum that can be used to reproduce large amplitude bending vibrations of flexible triatomic molecules with two stable linear equilibria. On the basis of our model and the recent vibrational potential [ J. Chem. Phys. 115, 3706 (2001) ], we analyze the HCN/CNH isomerizing molecule. We find that HCN/CNH has no monodromy and introduce the second global bending quantum number for this system at all energies where the potential is expected to work. We also show that LiNC/LiCN is a qualitatively different system with monodromy.

[Imaging of odontogenic tumors of the maxilla].

PubMed

Martin-Duverneuil, N; Sahli-Amor, M; Chiras, J

2009-05-01

Odontogenic tumors of the maxilla are frequent, mainly represented by cysts of the jaw. However, this group of tumors include a large number of potentially intricate pathologies whose evolution is dominated by frequent recurrences justifying long-term follow-up. When such a lesion is discovered, evaluation of imaging features combined with an extensive knowledge of the different patterns of other lesions (particularly their potentially evolutive patterns related to growth) can often suggest the diagnosis. While definitive diagnosis frequently relies on histology, it is not rare that the patterns are so intricate that final diagnosis is based on a correlation between clinical, imaging and histological findings.

Modelling and operation strategies of DLR's large scale thermocline test facility (TESIS)

NASA Astrophysics Data System (ADS)

Odenthal, Christian; Breidenbach, Nils; Bauer, Thomas

2017-06-01

In this work an overview of the TESIS:store thermocline test facility and its current construction status will be given. Based on this, the TESIS:store facility using sensible solid filler material is modelled with a fully transient model, implemented in MATLAB®. Results in terms of the impact of filler site and operation strategies will be presented. While low porosity and small particle diameters for the filler material are beneficial, operation strategy is one key element with potential for optimization. It is shown that plant operators have to ponder between utilization and exergetic efficiency. Different durations of the charging and discharging period enable further potential for optimizations.

Raising yield potential in wheat: increasing photosynthesis capacity and efficiency

USDA-ARS?s Scientific Manuscript database

Increasing wheat yields to help to ensure food security is a major challenge. Meeting this challenge requires a quantum improvement in the yield potential of wheat. Past increases in yield potential have largely resulted from improvements in harvest index not through increased biomass. Further large...

Nanostructural characterization of large-scale porous alumina fabricated via anodizing in arsenic acid solution

NASA Astrophysics Data System (ADS)

Akiya, Shunta; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

2017-05-01

Anodizing of aluminum in an arsenic acid solution is reported for the fabrication of anodic porous alumina. The highest potential difference (voltage) without oxide burning increased as the temperature and the concentration of the arsenic acid solution decreased, and a high anodizing potential difference of 340 V was achieved. An ordered porous alumina with several tens of cells was formed in 0.1-0.5 M arsenic acid solutions at 310-340 V for 20 h. However, the regularity of the porous alumina was not improved via anodizing for 72 h. No pore sealing behavior of the porous alumina was observed upon immersion in boiling distilled water, and it may be due to the formation of an insoluble complex on the oxide surface. The porous alumina consisted of two different layers: a hexagonal alumina layer that contained arsenic from the electrolyte and a pure alumina honeycomb skeleton. The porous alumina exhibited a white photoluminescence emission at approximately 515 nm under UV irradiation at 254 nm.

The coexistence temperature of hydrogen clathrates: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Luis, D. P.; Romero-Ramirez, I. E.; González-Calderón, A.; López-Lemus, J.

2018-03-01

Extensive molecular dynamics simulations in the equilibrium isobaric-isothermal (NPT) ensemble were developed to determine the coexistence temperatures of the water hydrogen mixture using the direct coexistence method. The water molecules were modeled using the four-site TIP4P/Ice analytical potential, and the hydrogen molecules were described using a three-site potential. The simulations were performed at different pressures (p = 900, 1500, 3000, and 4000 bars). At each pressure, a series of simulations were developed at different temperatures (from 230 to 270 K). Our results followed a line parallel to the experimental coexistence temperatures and underestimated these temperatures by approximately 25 K in the investigated range. The final configurations could or could not contain a fluid phase depending on the pressure, in accordance with the phase diagram. In addition, we explored the dynamics of the H2 molecules through clathrate hydrate cages and observed different behaviors of the H2 molecules in the small cages and the large cages of the sII structure.

The capture of heritable variation for genetic quality through social competition.

PubMed

Wolf, Jason B; Harris, W Edwin; Royle, Nick J

2008-09-01

In theory, females of many species choose mates based on traits that are indicators of male genetic quality. A fundamental question in evolutionary biology is why genetic variation for such indicator traits persists despite strong persistent selection imposed by female preference, which is known as the lek paradox. One potential solution to the lek paradox suggests that the traits that are targets of mate choice should evolve condition-dependent expression and that condition should have a large genetic variance. Condition is expected to exhibit high genetic variance because it is affected by a large number of physiological processes and hence, condition-dependent traits should 'capture' variation contributed by a large number of loci. We suggest that a potentially important cause of variation in condition is competition for limited resources. Here, we discuss a pair of models to analyze the evolutionary genetics of traits affected by success in social competition for resources. We show that competition can contribute to genetic variation of 'competition-dependent' traits that have fundamentally different evolutionary properties than other sources of variation. Competition dependence can make traits honest indicators of genetic quality by revealing the relative competitive ability of males, can provide a component of heritable variation that does not contribute to trait evolution, and can help maintain heritable variation under directional selection. Here we provide a general introduction to the concept of competition dependence and briefly introduce two models to demonstrate the potential evolutionary consequences of competition-dependent trait expression.

Empirical relations between large wood transport and catchment characteristics

NASA Astrophysics Data System (ADS)

Steeb, Nicolas; Rickenmann, Dieter; Rickli, Christian; Badoux, Alexandre

2017-04-01

The transport of vast amounts of large wood (LW) in water courses can considerably aggravate hazardous situations during flood events, and often strongly affects resulting flood damage. Large wood recruitment and transport are controlled by various factors which are difficult to assess and the prediction of transported LW volumes is difficult. Such information are, however, important for engineers and river managers to adequately dimension retention structures or to identify critical stream cross-sections. In this context, empirical formulas have been developed to estimate the volume of transported LW during a flood event (Rickenmann, 1997; Steeb et al., 2017). The data base of existing empirical wood load equations is, however, limited. The objective of the present study is to test and refine existing empirical equations, and to derive new relationships to reveal trends in wood loading. Data have been collected for flood events with LW occurrence in Swiss catchments of various sizes. This extended data set allows us to derive statistically more significant results. LW volumes were found to be related to catchment and transport characteristics, such as catchment size, forested area, forested stream length, water discharge, sediment load, or Melton ratio. Both the potential wood load and the fraction that is effectively mobilized during a flood event (effective wood load) are estimated. The difference of potential and effective wood load allows us to derive typical reduction coefficients that can be used to refine spatially explicit GIS models for potential LW recruitment.

Impacts devalue the potential of large-scale terrestrial CO2 removal through biomass plantations

NASA Astrophysics Data System (ADS)

Boysen, L. R.; Lucht, W.; Gerten, D.; Heck, V.

2016-09-01

Large-scale biomass plantations (BPs) are often considered a feasible and safe climate engineering proposal for extracting carbon from the atmosphere and, thereby, reducing global mean temperatures. However, the capacity of such terrestrial carbon dioxide removal (tCDR) strategies and their larger Earth system impacts remain to be comprehensively studied—even more so under higher carbon emissions and progressing climate change. Here, we use a spatially explicit process-based biosphere model to systematically quantify the potentials and trade-offs of a range of BP scenarios dedicated to tCDR, representing different assumptions about which areas are convertible. Based on a moderate CO2 concentration pathway resulting in a global mean warming of 2.5 °C above preindustrial level by the end of this century—similar to the Representative Concentration Pathway (RCP) 4.5—we assume tCDR to be implemented when a warming of 1.5 °C is reached in year 2038. Our results show that BPs can slow down the progression of increasing cumulative carbon in the atmosphere only sufficiently if emissions are reduced simultaneously like in the underlying RCP4.5 trajectory. The potential of tCDR to balance additional, unabated emissions leading towards a business-as-usual pathway alike RCP8.5 is therefore very limited. Furthermore, in the required large-scale applications, these plantations would induce significant trade-offs with food production and biodiversity and exert impacts on forest extent, biogeochemical cycles and biogeophysical properties.

Development and tests of MCP based timing and multiplicity detector for MIPs

NASA Astrophysics Data System (ADS)

Feofilov, G.; Kondratev, V.; Stolyarov, O.; Tulina, T.; Valiev, F.; Vinogradov, L.

2017-01-01

We present summary of technological developments and tests of the MCP based large area detector aimed at precise timing and charged particles multiplicity measurements. Results obtained in course of these developments of isochronous (simultaneity) precise signal readout, passive summation of 1 ns signals, fast (1 GHz) front-end electronics, miniature vacuum systems, etc. could be potentially interesting for a number of future applications in different fields.

Comparison of Birds Detected from Roadside and Off-Road Point Counts in the Shenandoah National Park

Treesearch

Cherry M.E. Keller; Mark R. Fuller

1995-01-01

Roadside point counts are generally used for large surveys to increase the number of samples. We examined differences in species detected from roadside versus off-road (200-m and 400-m) point counts in the Shenandoah National Park. We also compared the list of species detected in the first 3 minutes to those detected in 10 minutes for potential species biases. Results...

Highlighting Relationships of a Smartphone's Social Ecosystem in Potentially Large Investigations.

PubMed

Andriotis, Panagiotis; Oikonomou, George; Tryfonas, Theo; Li, Shancang

2016-09-01

Social media networks are becoming increasingly popular because they can satisfy diverse needs of individuals (both personal and professional). Modern mobile devices are empowered with increased capabilities, taking advantage of the technological progress that makes them smarter than their predecessors. Thus, a smartphone user is not only the phone owner, but also an entity that may have different facets and roles in various social media networks. We believe that these roles can be aggregated in a single social ecosystem, which can be derived by the smartphone. In this paper, we present our concept of the social ecosystem in contemporary devices and we attempt to distinguish the different communities that occur from the integration of social networking in our lives. In addition, we propose techniques to highlight major actors within the ecosystem. Moreover, we demonstrate our suggested visualization scheme, which illustrates the linking of entities that live in separate communities using data taken from the smartphone. Finally, we extend our concept to include various parallel ecosystems during potentially large investigations and we link influential entities in a vertical fashion. We particularly examine cases where data aggregation is performed by specific applications, producing volumes of textual data that can be analyzed with text mining methods. Our analysis demonstrates the risks of the rising "bring your own device" trend in enterprise environments.

Cigarette smoking and the oral microbiome in a large study of American adults

PubMed Central

Wu, Jing; Peters, Brandilyn A; Dominianni, Christine; Zhang, Yilong; Pei, Zhiheng; Yang, Liying; Ma, Yingfei; Purdue, Mark P; Jacobs, Eric J; Gapstur, Susan M; Li, Huilin; Alekseyenko, Alexander V; Hayes, Richard B; Ahn, Jiyoung

2016-01-01

Oral microbiome dysbiosis is associated with oral disease and potentially with systemic diseases; however, the determinants of these microbial imbalances are largely unknown. In a study of 1204 US adults, we assessed the relationship of cigarette smoking with the oral microbiome. 16S rRNA gene sequencing was performed on DNA from oral wash samples, sequences were clustered into operational taxonomic units (OTUs) using QIIME and metagenomic content was inferred using PICRUSt. Overall oral microbiome composition differed between current and non-current (former and never) smokers (P<0.001). Current smokers had lower relative abundance of the phylum Proteobacteria (4.6%) compared with never smokers (11.7%) (false discovery rate q=5.2 × 10−7), with no difference between former and never smokers; the depletion of Proteobacteria in current smokers was also observed at class, genus and OTU levels. Taxa not belonging to Proteobacteria were also associated with smoking: the genera Capnocytophaga, Peptostreptococcus and Leptotrichia were depleted, while Atopobium and Streptococcus were enriched, in current compared with never smokers. Functional analysis from inferred metagenomes showed that bacterial genera depleted by smoking were related to carbohydrate and energy metabolism, and to xenobiotic metabolism. Our findings demonstrate that smoking alters the oral microbiome, potentially leading to shifts in functional pathways with implications for smoking-related diseases. PMID:27015003

The role of interbasin groundwater transfers in geologically complex terranes, demonstrated by the Great Basin in the western United States

NASA Astrophysics Data System (ADS)

Nelson, Stephen T.; Mayo, Alan L.

2014-06-01

In the Great Basin, USA, bedrock interbasin flow is conceptualized as the mechanism by which large groundwater fluxes flow through multiple basins and intervening mountains. Interbasin flow is propounded based on: (1) water budget imbalances, (2) potential differences between basins, (3) stable isotope evidence, and (4) modeling studies. However, water budgets are too imprecise to discern interbasin transfers and potential differences may exist with or without interbasin fluxes. Potentiometric maps are dependent on conceptual underpinnings, leading to possible false inferences regarding interbasin transfers. Isotopic evidence is prone to non-unique interpretation and may be confounded by the effects of climate change. Structural and stratigraphic considerations in a geologically complex region like the Great Basin should produce compartmentalization, where increasing aquifer size increases the odds of segmentation along a given flow path. Initial conceptual hypotheses should explain flow with local recharge and short flow paths. Where bedrock interbasin flow is suspected, it is most likely controlled by diversion of water into the damage zones of normal faults, where fault cores act as barriers. Large-scale bedrock interbasin flow where fluxes must transect multiple basins, ranges, and faults at high angles should be the conceptual model of last resort.

Rhizosphere biophysics and root water uptake

NASA Astrophysics Data System (ADS)

Carminati, Andrea; Zarebanadkouki, Mohsen; Ahmed, Mutez A.; Passioura, John

2016-04-01

The flow of water into the roots and the (putative) presence of a large resistance at the root-soil interface have attracted the attention of plant and soil scientists for decades. Such resistance has been attributed to a partial contact between roots and soil, large gradients in soil matric potential around the roots, or accumulation of solutes at the root surface creating a negative osmotic potential. Our hypothesis is that roots are capable of altering the biophysical properties of the soil around the roots, the rhizosphere, facilitating root water uptake in dry soils. In particular, we expect that root hairs and mucilage optimally connect the roots to the soil maintaining the hydraulic continuity across the rhizosphere. Using a pressure chamber apparatus we measured the relation between transpiration rate and the water potential difference between soil and leaf xylem during drying cycles in barley mutants with and without root hairs. The samples were grown in well structured soils. At low soil moistures and high transpiration rates, large drops in water potential developed around the roots. These drops in water potential recovered very slowly, even after transpiration was severely decreased. The drops in water potential were much bigger in barley mutants without root hairs. These mutants failed to sustain high transpiration rates in dry conditions. To explain the nature of such drops in water potential across the rhizosphere we performed high resolution neutron tomography of the rhizosphere of the barleys with and without root hairs growing in the same soil described above. The tomograms suggested that the hydraulic contact between the soil structures was the highest resistance for the water flow in dry conditions. The tomograms also indicate that root hairs and mucilage improved the hydraulic contact between roots and soil structures. At high transpiration rates and low water contents, roots extracted water from the rhizosphere, while the bulk soil, due its low unsaturated conductivity, failed to compensate root water uptake. We conclude that root hairs are functional to increase the contact area between the roots and the soil structures and mucilage maintains wet the soil region between root hairs. These observations demonstrate the importance of the biophysical processes in the rhizosphere in modulating root water uptake.

Large underground, liquid based detectors for astro-particle physics in Europe: scientific case and prospects

NASA Astrophysics Data System (ADS)

Autiero, D.; Äystö, J.; Badertscher, A.; Bezrukov, L.; Bouchez, J.; Bueno, A.; Busto, J.; Campagne, J.-E.; Cavata, Ch; Chaussard, L.; de Bellefon, A.; Déclais, Y.; Dumarchez, J.; Ebert, J.; Enqvist, T.; Ereditato, A.; von Feilitzsch, F.; Fileviez Perez, P.; Göger-Neff, M.; Gninenko, S.; Gruber, W.; Hagner, C.; Hess, M.; Hochmuth, K. A.; Kisiel, J.; Knecht, L.; Kreslo, I.; Kudryavtsev, V. A.; Kuusiniemi, P.; Lachenmaier, T.; Laffranchi, M.; Lefievre, B.; Lightfoot, P. K.; Lindner, M.; Maalampi, J.; Maltoni, M.; Marchionni, A.; Marrodán Undagoitia, T.; Marteau, J.; Meregaglia, A.; Messina, M.; Mezzetto, M.; Mirizzi, A.; Mosca, L.; Moser, U.; Müller, A.; Natterer, G.; Oberauer, L.; Otiougova, P.; Patzak, T.; Peltoniemi, J.; Potzel, W.; Pistillo, C.; Raffelt, G. G.; Rondio, E.; Roos, M.; Rossi, B.; Rubbia, A.; Savvinov, N.; Schwetz, T.; Sobczyk, J.; Spooner, N. J. C.; Stefan, D.; Tonazzo, A.; Trzaska, W.; Ulbricht, J.; Volpe, C.; Winter, J.; Wurm, M.; Zalewska, A.; Zimmermann, R.

2007-11-01

This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatuses employ three different and, to some extent, complementary detection techniques: GLACIER (liquid argon TPC), LENA (liquid scintillator) and MEMPHYS (water Cherenkov), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to open and outstanding physics issues such as the search for matter instability, the detection of astrophysical neutrinos and geo-neutrinos and to the possible use of these detectors in future high intensity neutrino beams.

Improved cache performance in Monte Carlo transport calculations using energy banding

NASA Astrophysics Data System (ADS)

Siegel, A.; Smith, K.; Felker, K.; Romano, P.; Forget, B.; Beckman, P.

2014-04-01

We present an energy banding algorithm for Monte Carlo (MC) neutral particle transport simulations which depend on large cross section lookup tables. In MC codes, read-only cross section data tables are accessed frequently, exhibit poor locality, and are typically too much large to fit in fast memory. Thus, performance is often limited by long latencies to RAM, or by off-node communication latencies when the data footprint is very large and must be decomposed on a distributed memory machine. The proposed energy banding algorithm allows maximal temporal reuse of data in band sizes that can flexibly accommodate different architectural features. The energy banding algorithm is general and has a number of benefits compared to the traditional approach. In the present analysis we explore its potential to achieve improvements in time-to-solution on modern cache-based architectures.

Review Of E-Beam Electrical Test Techniques

NASA Astrophysics Data System (ADS)

Hohn, Fritz J.

1987-09-01

Electron beams as a viable technique for contactless testing of electrical functions and electrical integrity of different active devices in VLSI-chips has been demonstrated over the past years. This method of testing electronic networks, most widely used in the laboratory environment, is based on an electron probe which is deflected from point to point in the network. A current of secondary electrons emitted in response to the impingement of the electron probe is converted to a signal indicating the presence of a voltage or varying potential at the different points. Voltage contrast, electron beam induced current, dual potential approach, stroboscopic techniques and other methods have been developed and are used to detect different functional failures in devices. Besides the VLSI application, the contactless testing of three dimensional conductor networks of a 10cm x 10cm x .8cm multilayer ceramic module poses a different and new application for the electron beam test technique. A dual potential electron beam test system allows to generate electron beam induced voltage contrast. The same system at a different potential is used to detect this voltage contrast over the large area without moving the substrate and thus test for the electrical integrity of the networks. Less attention in most of the applications has been paid to the electron optical environment, mostly SEM's were upgraded or converted to do the job of a "voltage contrast" machine. This by no means will satisfy all requirements and more thoughts have to be given to aspects such as: low voltage electron guns: thermal emitter, Schottky emitter, field emitter, low voltage electron optics, two lens systems, different means of detection, signal processing - storage and others. This paper will review available E-beam test techniques, specific applications and some critical components.

Circulating avian influenza viruses closely related to the 1918 virus have pandemic potential

PubMed Central

Watanabe, Tokiko; Zhong, Gongxun; Russell, Colin A.; Nakajima, Noriko; Hatta, Masato; Hanson, Anthony; McBride, Ryan; Burke, David F.; Takahashi, Kenta; Fukuyama, Satoshi; Tomita, Yuriko; Maher, Eileen A.; Watanabe, Shinji; Imai, Masaki; Neumann, Gabriele; Hasegawa, Hideki; Paulson, James C.; Smith, Derek J.; Kawaoka, Yoshihiro

2014-01-01

Summary Wild birds harbor a large gene pool of influenza A viruses that have the potential to cause influenza pandemics. Foreseeing and understanding this potential is important for effective surveillance. Our phylogenetic and geographic analyses revealed the global prevalence of avian influenza virus genes whose proteins differ only a few amino acids from the 1918 pandemic influenza virus, suggesting that 1918-like pandemic viruses may emerge in the future. To assess this risk, we generated and characterized a virus composed of avian influenza viral segments with high homology to the 1918 virus. This virus exhibited higher pathogenicity in mice and ferrets than an authentic avian influenza virus. Further, acquisition of seven amino acid substitutions in the viral polymerases and the hemagglutinin surface glycoprotein conferred respiratory droplet transmission to the 1918-like avian virus in ferrets, demonstrating that contemporary avian influenza viruses with 1918 virus-like proteins may have pandemic potential. PMID:24922572

Modeling the Energy Use of a Connected and Automated Transportation System (Poster)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonder, J.; Brown, A.

Early research points to large potential impacts of connected and automated vehicles (CAVs) on transportation energy use - dramatic savings, increased use, or anything in between. Due to a lack of suitable data and integrated modeling tools to explore these complex future systems, analyses to date have relied on simple combinations of isolated effects. This poster proposes a framework for modeling the potential energy implications from increasing penetration of CAV technologies and for assessing technology and policy options to steer them toward favorable energy outcomes. Current CAV modeling challenges include estimating behavior change, understanding potential vehicle-to-vehicle interactions, and assessing trafficmore » flow and vehicle use under different automation scenarios. To bridge these gaps and develop a picture of potential future automated systems, NREL is integrating existing modeling capabilities with additional tools and data inputs to create a more fully integrated CAV assessment toolkit.« less

An overview on the TACTS mission using the new German research aircraft HALO in summer 2012

NASA Astrophysics Data System (ADS)

Engel, Andreas; Boenisch, Harald

2013-04-01

The TACTS (Transport and Composition in the UTLS) mission is the first large atmospheric mission of the new German research aircraft HALO. TACTS aims at improving our understanding of the transport processes which determine the chemical composition in the UTLS with a special emphasis on the transition from summer to fall. The mission was flown in August and September 2012 with a fully equipped aircraft carrying 13 different instruments measuring a wide range of chemical tracers with different lifetimes and different source-sink characteristics. The payload consists of both in-situ and remote sensing instruments. In addition to TACTS the same payload was employed to measure the chemical composition during a large north-south transect as part of the ESMVal project. Data are available up to to altitudes above 15 km, potential temperatures above 400 K and covering the latitude range from 65°S to 80°N. Due to the large payload a very wide range of measurements allows for a very good characterisation of the chemical composition. All instruments performed well and close to complete data sets are available for all flights performed during both missions. We present an overview of the scientific aims of TACTS, the payload, the measurements performed and some selected first results.

Confirmation of general relativity on large scales from weak lensing and galaxy velocities.

PubMed

Reyes, Reinabelle; Mandelbaum, Rachel; Seljak, Uros; Baldauf, Tobias; Gunn, James E; Lombriser, Lucas; Smith, Robert E

2010-03-11

Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, E(G), that combines measures of large-scale gravitational lensing, galaxy clustering and structure growth rate. The combination is insensitive to 'galaxy bias' (the difference between the clustering of visible galaxies and invisible dark matter) and is thus robust to the uncertainty in this parameter. Modified theories of gravity generally predict values of E(G) different from the general relativistic prediction because, in these theories, the 'gravitational slip' (the difference between the two potentials that describe perturbations in the gravitational metric) is non-zero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that E(G) = 0.39 +/- 0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of E(G) approximately 0.4. The measured value excludes a model within the tensor-vector-scalar gravity theory, which modifies both Newtonian and Einstein gravity. However, the relatively large uncertainty still permits models within f(R) theory, which is an extension of general relativity. A fivefold decrease in uncertainty is needed to rule out these models.

Confirmation of general relativity on large scales from weak lensing and galaxy velocities

NASA Astrophysics Data System (ADS)

Reyes, Reinabelle; Mandelbaum, Rachel; Seljak, Uros; Baldauf, Tobias; Gunn, James E.; Lombriser, Lucas; Smith, Robert E.

2010-03-01

Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, EG, that combines measures of large-scale gravitational lensing, galaxy clustering and structure growth rate. The combination is insensitive to `galaxy bias' (the difference between the clustering of visible galaxies and invisible dark matter) and is thus robust to the uncertainty in this parameter. Modified theories of gravity generally predict values of EG different from the general relativistic prediction because, in these theories, the `gravitational slip' (the difference between the two potentials that describe perturbations in the gravitational metric) is non-zero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that EG = 0.39+/-0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of EG~0.4. The measured value excludes a model within the tensor-vector-scalar gravity theory, which modifies both Newtonian and Einstein gravity. However, the relatively large uncertainty still permits models within f() theory, which is an extension of general relativity. A fivefold decrease in uncertainty is needed to rule out these models.

Thermal characterizations of a large-format lithium ion cell focused on high current discharges

NASA Astrophysics Data System (ADS)

Veth, C.; Dragicevic, D.; Merten, C.

2014-12-01

The thermal behavior of a large-format lithium ion cell has been investigated during measurements on cell and battery level. High current discharges up to 300 A are the main topic of this study. This paper demonstrates that the temperature response to high current loads provides the possibility to investigate internal cell parameters and their inhomogeneity. In order to identify thermal response caused by internal cell processes, the heat input due to contact resistances has been minimized. The differences between the thermal footprint of a cell during cell and battery measurements are being addressed. The study presented here focuses on the investigation of thermal hot and cold spots as well as temperature gradients in a 50 Ah pouch cell. Furthermore, it is demonstrated that the difference between charge and discharge can have significant influence on the thermal behavior of lithium ion cells. Moreover, the miscellaneous thermal characteristics of differently aged lithium ion cells highlight the possibility of an ex-situ non-destructive post-mortem-analysis, providing the possibility of a qualitative and quantitative characterization of inhomogeneous cell-aging. These investigations also generate excellent data for the validation and parameterization of electro-thermal cell models, predicting the distribution of temperature, current, potential, SOC and SOH inside large-format cells.

Plasma dynamics on current-carrying magnetic flux tubes

NASA Technical Reports Server (NTRS)

Swift, Daniel W.

1992-01-01

A 1D numerical simulation is used to investigate the evolution of a plasma in a current-carrying magnetic flux tube of variable cross section. A large potential difference, parallel to the magnetic field, is applied across the domain. The result is that density minimum tends to deepen, primarily in the cathode end, and the entire potential drop becomes concentrated across the region of density minimum. The evolution of the simulation shows some sensitivity to particle boundary conditions, but the simulations inevitably evolve into a final state with a nearly stationary double layer near the cathode end. The simulation results are at sufficient variance with observations that it appears unlikely that auroral electrons can be explained by a simple process of acceleration through a field-aligned potential drop.

Breathing Bright Solitons in a Bose Einstein Condensate

NASA Astrophysics Data System (ADS)

Chong, Gui-Shu; Hai, Wen-Hua; Xie, Qiong-Tao

2003-12-01

A Bose-Einstein condensate with time varying scattering length in time-dependent harmonic trap is analytically investigated and soliton-like solutions of the Gross-Pitaeviskii equation are obtained to describe single soliton, bisoliton and N-soliton properties of the matter wave. The influences of the geometrical property and modulate frequency of trapping potential on soliton behaviour are discussed. When the trap potential has a very small trap aspect ratio or oscillates with a high frequency, the matter wave preserves its shape nearly like a soliton train in propagation, while the breathing behaviour, which displays the periodic collapse and revival of the matter wave, is found for a relatively large aspect ratio or slow varying potential. Meanwhile mass centre of the matter wave translates and/or oscillates for different trap aspect ratio and trap frequencies.

Using variance structure to quantify responses to perturbation in fish catches

USGS Publications Warehouse

Vidal, Tiffany E.; Irwin, Brian J.; Wagner, Tyler; Rudstam, Lars G.; Jackson, James R.; Bence, James R.

2017-01-01

We present a case study evaluation of gill-net catches of Walleye Sander vitreus to assess potential effects of large-scale changes in Oneida Lake, New York, including the disruption of trophic interactions by double-crested cormorants Phalacrocorax auritus and invasive dreissenid mussels. We used the empirical long-term gill-net time series and a negative binomial linear mixed model to partition the variability in catches into spatial and coherent temporal variance components, hypothesizing that variance partitioning can help quantify spatiotemporal variability and determine whether variance structure differs before and after large-scale perturbations. We found that the mean catch and the total variability of catches decreased following perturbation but that not all sampling locations responded in a consistent manner. There was also evidence of some spatial homogenization concurrent with a restructuring of the relative productivity of individual sites. Specifically, offshore sites generally became more productive following the estimated break point in the gill-net time series. These results provide support for the idea that variance structure is responsive to large-scale perturbations; therefore, variance components have potential utility as statistical indicators of response to a changing environment more broadly. The modeling approach described herein is flexible and would be transferable to other systems and metrics. For example, variance partitioning could be used to examine responses to alternative management regimes, to compare variability across physiographic regions, and to describe differences among climate zones. Understanding how individual variance components respond to perturbation may yield finer-scale insights into ecological shifts than focusing on patterns in the mean responses or total variability alone.

Symmetry energy III: Isovector skins

NASA Astrophysics Data System (ADS)

Danielewicz, Paweł; Singh, Pardeep; Lee, Jenny

2017-02-01

Isoscalar density is a sum of neutron and proton densities and isovector is a normalized difference. Here, we report the experimental evidence for the displacement of the isovector and isoscalar surfaces in nuclei, by ∼ 0.9 fm from each other. We analyze data on quasielastic (QE) charge exchange (p,n) reactions, concurrently with proton and neutron elastic scattering data for the same target nuclei, following the concepts of the isoscalar and isovector potentials combined into Lane optical potential. The elastic data largely probe the geometry of the isoscalar potential and the (p,n) data largely probe a relation between the geometries of the isovector and isoscalar potentials. The targets include 48Ca, 90Zr, 120Sn and 208Pb and projectile incident energy values span the range of (10-50) MeV. In our fit to elastic and QE charge-exchange data, we allow the values of isoscalar and isovector radii, diffusivities and overall potential normalizations to float away from those in the popular Koning and Delaroche parametrization. We find that the best-fit isovector radii are consistently larger than isoscalar and the best-fit isovector surfaces are steeper. Upon identifying the displacement of the potential surfaces with the displacement of the surfaces for the densities in the Skyrme-Hartree-Fock calculations, and by supplementing the results with those from analyzing excitation energies to isobaric analog states in the past, we arrive at the slope and value of the symmetry energy at normal density of 70 < L < 101 MeV and 33.5 < aaV < 36.4 MeV, respectively.

Toward production from gas hydrates: Current status, assessment of resources, and simulation-based evaluation of technology and potential

USGS Publications Warehouse

Moridis, G.J.; Collett, T.S.; Boswell, R.; Kurihara, M.; Reagan, M.T.; Koh, C.; Sloan, E.D.

2009-01-01

Gas hydrates (GHs) are a vast energy resource with global distribution in the permafrost and in the oceans. Even if conservative estimates are considered and only a small fraction is recoverable, the sheer size of the resource is so large that it demands evaluation as a potential energy source. In this review paper, we discuss the distribution of natural GH accumulations, the status of the primary international research and development (R&D) programs, and the remaining science and technological challenges facing the commercialization of production. After a brief examination of GH accumulations that are well characterized and appear to be models for future development and gas production, we analyze the role of numerical simulation in the assessment of the hydrate-production potential, identify the data needs for reliable predictions, evaluate the status of knowledge with regard to these needs, discuss knowledge gaps and their impact, and reach the conclusion that the numerical-simulation capabilities are quite advanced and that the related gaps either are not significant or are being addressed. We review the current body of literature relevant to potential productivity from different types of GH deposits and determine that there are consistent indications of a large production potential at high rates across long periods from a wide variety of hydrate deposits. Finally, we identify (a) features, conditions, geology and techniques that are desirable in potential production targets; (b) methods to maximize production; and (c) some of the conditions and characteristics that render certain GH deposits undesirable for production. Copyright ?? 2009 Society of Petroleum Engineers.

Toward production from gas hydrates: Current status, assessment of resources, and simulation-based evaluation of technology and potential

USGS Publications Warehouse

Moridis, G.J.; Collett, T.S.; Boswell, R.; Kurihara, M.; Reagan, M.T.; Koh, C.; Sloan, E.D.

2008-01-01

Gas hydrates are a vast energy resource with global distribution in the permafrost and in the oceans. Even if conservative estimates are considered and only a small fraction is recoverable, the sheer size of the resource is so large that it demands evaluation as a potential energy source. In this review paper, we discuss the distribution of natural gas hydrate accumulations, the status of the primary international R&D programs, and the remaining science and technological challenges facing commercialization of production. After a brief examination of gas hydrate accumulations that are well characterized and appear to be models for future development and gas production, we analyze the role of numerical simulation in the assessment of the hydrate production potential, identify the data needs for reliable predictions, evaluate the status of knowledge with regard to these needs, discuss knowledge gaps and their impact, and reach the conclusion that the numerical simulation capabilities are quite advanced and that the related gaps are either not significant or are being addressed. We review the current body of literature relevant to potential productivity from different types of gas hydrate deposits, and determine that there are consistent indications of a large production potential at high rates over long periods from a wide variety of hydrate deposits. Finally, we identify (a) features, conditions, geology and techniques that are desirable in potential production targets, (b) methods to maximize production, and (c) some of the conditions and characteristics that render certain gas hydrate deposits undesirable for production. Copyright 2008, Society of Petroleum Engineers.

Trends in Trace Element Fractionation Between Foraminiferal Species and the Role of Biomineralization

NASA Astrophysics Data System (ADS)

Reichart, G. J.; Nooijer, L. D.; Geerken, E.; Mezger, E.; van Dijk, I. V.; Daemmer, L. K.

2017-12-01

Reconstructions of past climate and environments are largely based on stable isotopes and trace element concentrations measured on fossil foraminiferal calcite. Their element and isotope composition roughly reflects seawater composition and physical conditions, which in turn, are related to paleoceanographic parameters. More recently, attempts are being made to infer ranges in environmental parameters using the observed differences in the composition within individual tests. Remarkably, inter-species differences in trace element incorporation are well-correlated over a wide range of environmental conditions. This is particularly remarkable knowing that different environmental factors influence incorporation of these elements at various magnitudes. Most likely the complex biomineralization of foraminifera potentially offsets trace elements similarly at all these scales and also between different species. This suggests that at least parts of the mechanisms underlying foraminiferal biomineralization are similar for all species, which in turn provides important clues on the cellular mechanisms operating during calcification. Moreover, the systematics in trace element partitioning between species could potentially provide important clues for unravelling past changes in trace element composition of the ancient ocean.

Pharmaceuticals and personal care products (PPCPs): a review on environmental contamination in China.

PubMed

Liu, Jin-Lin; Wong, Ming-Hung

2013-09-01

Pharmaceuticals and personal care products (PPCPs) which contain diverse organic groups, such as antibiotics, hormones, antimicrobial agents, synthetic musks, etc., have raised significant concerns in recently years for their persistent input and potential threat to ecological environment and human health. China is a large country with high production and consumption of PPCPs for its economic development and population growth in recent years. This may result in PPCP contamination in different environmental media of China. This review summarizes the current contamination status of different environment media, including sewage, surface water, sludge, sediments, soil, and wild animals, in China by PPCPs. The human body burden and adverse effects derived from PPCPs are also evaluated. Based on this review, it has been concluded that more contamination information of aquatic environment and wildlife as well as human body burden of PPCPs in different areas of China is urgent. Studies about their environmental behavior and control technologies need to be conducted, and acute and chronic toxicities of different PPCP groups should be investigated for assessing their potential ecological and health risks. © 2013.

Room temperature ionic liquids: A simple model. Effect of chain length and size of intermolecular potential on critical temperature.

PubMed

Chapela, Gustavo A; Guzmán, Orlando; Díaz-Herrera, Enrique; del Río, Fernando

2015-04-21

A model of a room temperature ionic liquid can be represented as an ion attached to an aliphatic chain mixed with a counter ion. The simple model used in this work is based on a short rigid tangent square well chain with an ion, represented by a hard sphere interacting with a Yukawa potential at the head of the chain, mixed with a counter ion represented as well by a hard sphere interacting with a Yukawa potential of the opposite sign. The length of the chain and the depth of the intermolecular forces are investigated in order to understand which of these factors are responsible for the lowering of the critical temperature. It is the large difference between the ionic and the dispersion potentials which explains this lowering of the critical temperature. Calculation of liquid-vapor equilibrium orthobaric curves is used to estimate the critical points of the model. Vapor pressures are used to obtain an estimate of the triple point of the different models in order to calculate the span of temperatures where they remain a liquid. Surface tensions and interfacial thicknesses are also reported.

Hippocampus duality: Memory and novelty detection are subserved by distinct mechanisms.

PubMed

Barbeau, Emmanuel J; Chauvel, Patrick; Moulin, Christopher J A; Regis, Jean; Liégeois-Chauvel, Catherine

2017-04-01

The hippocampus plays a pivotal role both in novelty detection and in long-term memory. The physiological mechanisms underlying these behaviors have yet to be understood in humans. We recorded intracerebral evoked potentials within the hippocampus of epileptic patients (n = 10) during both memory and novelty detection tasks (targets in oddball tasks). We found that memory and detection tasks elicited late local field potentials in the hippocampus during the same period, but of opposite polarity (negative during novelty detection tasks, positive during memory tasks, ∼260-600 ms poststimulus onset, P < 0.05). Critically, these potentials had maximal amplitude on the same contact in the hippocampus for each patient. This pattern did not depend on the task as different types of memory and novelty detection tasks were used. It did not depend on the novelty of the stimulus or the difficulty of the task either. Two different hypotheses are discussed to account for this result: it is either due to the activation of CA1 pyramidal neurons by two different pathways such as the monosynaptic and trisynaptic entorhinal-hippocampus pathways, or to the activation of different neuronal populations, that is, differing either functionally (e.g., novelty/familiarity neurons) or located in different regions of the hippocampus (e.g., CA1/subiculum). In either case, these activities may integrate the activity of two distinct large-scale networks implementing externally or internally oriented, mutually exclusive, brain states. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Double layers and double wells in arbitrary degenerate plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akbari-Moghanjoughi, M.

Using the generalized hydrodynamic model, the possibility of variety of large amplitude nonlinear excitations is examined in electron-ion plasma with arbitrary electron degeneracy considering also the ion temperature effect. A new energy-density relation is proposed for plasmas with arbitrary electron degeneracy which reduces to the classical Boltzmann and quantum Thomas-Fermi counterparts in the extreme limits. The pseudopotential method is employed to find the criteria for existence of nonlinear structures such as solitons, periodic nonlinear structures, and double-layers for different cases of adiabatic and isothermal ion fluids for a whole range of normalized electron chemical potential, η{sub 0}, ranging from dilutemore » classical to completely degenerate electron fluids. It is observed that there is a Mach-speed gap in which no large amplitude localized or periodic nonlinear excitations can propagate in the plasma under consideration. It is further revealed that the plasma under investigation supports propagation of double-wells and double-layers the chemical potential and Mach number ranges of which are studied in terms of other plasma parameters. The Mach number criteria for nonlinear waves are shown to significantly differ for cases of classical with η{sub 0} < 0 and quantum with η{sub 0} > 0 regimes. It is also shown that the localized structure propagation criteria possess significant dissimilarities for plasmas with adiabatic and isothermal ions. Current research may be generalized to study the nonlinear structures in plasma containing positrons, multiple ions with different charge states, and charged dust grains.« less

Functional tradeoffs underpin salinity-driven divergence in microbial community composition.

PubMed

Dupont, Chris L; Larsson, John; Yooseph, Shibu; Ininbergs, Karolina; Goll, Johannes; Asplund-Samuelsson, Johannes; McCrow, John P; Celepli, Narin; Allen, Lisa Zeigler; Ekman, Martin; Lucas, Andrew J; Hagström, Åke; Thiagarajan, Mathangi; Brindefalk, Björn; Richter, Alexander R; Andersson, Anders F; Tenney, Aaron; Lundin, Daniel; Tovchigrechko, Andrey; Nylander, Johan A A; Brami, Daniel; Badger, Jonathan H; Allen, Andrew E; Rusch, Douglas B; Hoffman, Jeff; Norrby, Erling; Friedman, Robert; Pinhassi, Jarone; Venter, J Craig; Bergman, Birgitta

2014-01-01

Bacterial community composition and functional potential change subtly across gradients in the surface ocean. In contrast, while there are significant phylogenetic divergences between communities from freshwater and marine habitats, the underlying mechanisms to this phylogenetic structuring yet remain unknown. We hypothesized that the functional potential of natural bacterial communities is linked to this striking divide between microbiomes. To test this hypothesis, metagenomic sequencing of microbial communities along a 1,800 km transect in the Baltic Sea area, encompassing a continuous natural salinity gradient from limnic to fully marine conditions, was explored. Multivariate statistical analyses showed that salinity is the main determinant of dramatic changes in microbial community composition, but also of large scale changes in core metabolic functions of bacteria. Strikingly, genetically and metabolically different pathways for key metabolic processes, such as respiration, biosynthesis of quinones and isoprenoids, glycolysis and osmolyte transport, were differentially abundant at high and low salinities. These shifts in functional capacities were observed at multiple taxonomic levels and within dominant bacterial phyla, while bacteria, such as SAR11, were able to adapt to the entire salinity gradient. We propose that the large differences in central metabolism required at high and low salinities dictate the striking divide between freshwater and marine microbiomes, and that the ability to inhabit different salinity regimes evolved early during bacterial phylogenetic differentiation. These findings significantly advance our understanding of microbial distributions and stress the need to incorporate salinity in future climate change models that predict increased levels of precipitation and a reduction in salinity.

Transport of fluorobenzoate tracers in a vegetated hydrologic control volume: 1. Experimental results

NASA Astrophysics Data System (ADS)

Queloz, Pierre; Bertuzzo, Enrico; Carraro, Luca; Botter, Gianluca; Miglietta, Franco; Rao, P. S. C.; Rinaldo, Andrea

2015-04-01

This paper reports about the experimental evidence collected on the transport of five fluorobenzoate tracers injected under controlled conditions in a vegetated hydrologic volume, a large lysimeter (fitted with load cells, sampling ports, and an underground chamber) where two willows prompting large evapotranspiration fluxes had been grown. The relevance of the study lies in the direct and indirect measures of the ways in which hydrologic fluxes, in this case, evapotranspiration from the upper surface and discharge from the bottom drainage, sample water and solutes in storage at different times under variable hydrologic forcings. Methods involve the accurate control of hydrologic inputs and outputs and a large number of suitable chemical analyses of water samples in discharge waters. Mass extraction from biomass has also been performed ex post. The results of the 2 year long experiment established that our initial premises on the tracers' behavior, known to be sorption-free under saturated conditions which we verified in column leaching tests, were unsuitable as large differences in mass recovery appeared. Issues on reactivity thus arose and were addressed in the paper, in this case attributed to microbial degradation and solute plant uptake. Our results suggest previously unknown features of fluorobenzoate compounds as hydrologic tracers, potentially interesting for catchment studies owing to their suitability for distinguishable multiple injections, and an outlook on direct experimental closures of mass balance in hydrologic transport volumes involving fluxes that are likely to sample differently stored water and solutes.

The complex evolutionary history of big-eared horseshoe bats (Rhinolophus macrotis complex): insights from genetic, morphological and acoustic data

PubMed Central

Sun, Keping; Kimball, Rebecca T.; Liu, Tong; Wei, Xuewen; Jin, Longru; Jiang, Tinglei; Lin, Aiqing; Feng, Jiang

2016-01-01

Palaeoclimatic oscillations and different landscapes frequently result in complex population-level structure or the evolution of cryptic species. Elucidating the potential mechanisms is vital to understanding speciation events. However, such complex evolutionary patterns have rarely been reported in bats. In China, the Rhinolophus macrotis complex contains a large form and a small form, suggesting the existence of a cryptic bat species. Our field surveys found these two sibling species have a continuous and widespread distribution with partial sympatry. However, their evolutionary history has received little attention. Here, we used extensive sampling, morphological and acoustic data, as well as different genetic markers to investigate their evolutionary history. Genetic analyses revealed discordance between the mitochondrial and nuclear data. Mitochondrial data identified three reciprocally monophyletic lineages: one representing all small forms from Southwest China, and the other two containing all large forms from Central and Southeast China, respectively. The large form showed paraphyly with respect to the small form. However, clustering analyses of microsatellite and Chd1 gene sequences support two divergent clusters separating the large form and the small form. Moreover, morphological and acoustic analyses were consistent with nuclear data. This unusual pattern in the R. macrotis complex might be accounted for by palaeoclimatic oscillations, shared ancestral polymorphism and/or interspecific hybridization. PMID:27748429

Visualizing phylogenetic tree landscapes.

PubMed

Wilgenbusch, James C; Huang, Wen; Gallivan, Kyle A

2017-02-02

Genomic-scale sequence alignments are increasingly used to infer phylogenies in order to better understand the processes and patterns of evolution. Different partitions within these new alignments (e.g., genes, codon positions, and structural features) often favor hundreds if not thousands of competing phylogenies. Summarizing and comparing phylogenies obtained from multi-source data sets using current consensus tree methods discards valuable information and can disguise potential methodological problems. Discovery of efficient and accurate dimensionality reduction methods used to display at once in 2- or 3- dimensions the relationship among these competing phylogenies will help practitioners diagnose the limits of current evolutionary models and potential problems with phylogenetic reconstruction methods when analyzing large multi-source data sets. We introduce several dimensionality reduction methods to visualize in 2- and 3-dimensions the relationship among competing phylogenies obtained from gene partitions found in three mid- to large-size mitochondrial genome alignments. We test the performance of these dimensionality reduction methods by applying several goodness-of-fit measures. The intrinsic dimensionality of each data set is also estimated to determine whether projections in 2- and 3-dimensions can be expected to reveal meaningful relationships among trees from different data partitions. Several new approaches to aid in the comparison of different phylogenetic landscapes are presented. Curvilinear Components Analysis (CCA) and a stochastic gradient decent (SGD) optimization method give the best representation of the original tree-to-tree distance matrix for each of the three- mitochondrial genome alignments and greatly outperformed the method currently used to visualize tree landscapes. The CCA + SGD method converged at least as fast as previously applied methods for visualizing tree landscapes. We demonstrate for all three mtDNA alignments that 3D projections significantly increase the fit between the tree-to-tree distances and can facilitate the interpretation of the relationship among phylogenetic trees. We demonstrate that the choice of dimensionality reduction method can significantly influence the spatial relationship among a large set of competing phylogenetic trees. We highlight the importance of selecting a dimensionality reduction method to visualize large multi-locus phylogenetic landscapes and demonstrate that 3D projections of mitochondrial tree landscapes better capture the relationship among the trees being compared.

Similarities and differences in ablative and non-ablative iron oxide nanoparticle hyperthermia cancer treatment

NASA Astrophysics Data System (ADS)

Petryk, Alicia A.; Misra, Adwiteeya; Kastner, Elliot J.; Mazur, Courtney M.; Petryk, James D.; Hoopes, P. Jack

2015-03-01

The use of hyperthermia to treat cancer is well studied and has utilized numerous delivery techniques, including microwaves, radio frequency, focused ultrasound, induction heating, infrared radiation, warmed perfusion liquids (combined with chemotherapy), and recently, metallic nanoparticles (NP) activated by near infrared radiation (NIR) and alternating magnetic field (AMF) based platforms. It has been demonstrated by many research groups that ablative temperatures and cytotoxicity can be produced with locally NP-based hyperthermia. Such ablative NP techniques have demonstrated the potential for success. Much attention has also been given to the fact that NP may be administered systemically, resulting in a broader cancer therapy approach, a lower level of tumor NP content and a different type of NP cancer therapy (most likely in the adjuvant setting). To use NP based hyperthermia successfully as a cancer treatment, the technique and its goal must be understood and utilized in the appropriate clinical context. The parameters include, but are not limited to, NP access to the tumor (large vs. small quantity), cancer cell-specific targeting, drug carrying capacity, potential as an ionizing radiation sensitizer, and the material properties (magnetic characteristics, size and charge). In addition to their potential for cytotoxicity, the material properties of the NP must also be optimized for imaging, detection and direction. In this paper we will discuss the differences between, and potential applications for, ablative and non-ablative magnetic nanoparticle hyperthermia.

Latency correction of event-related potentials between different experimental protocols

NASA Astrophysics Data System (ADS)

Iturrate, I.; Chavarriaga, R.; Montesano, L.; Minguez, J.; Millán, JdR

2014-06-01

Objective. A fundamental issue in EEG event-related potentials (ERPs) studies is the amount of data required to have an accurate ERP model. This also impacts the time required to train a classifier for a brain-computer interface (BCI). This issue is mainly due to the poor signal-to-noise ratio and the large fluctuations of the EEG caused by several sources of variability. One of these sources is directly related to the experimental protocol or application designed, and may affect the amplitude or latency of ERPs. This usually prevents BCI classifiers from generalizing among different experimental protocols. In this paper, we analyze the effect of the amplitude and the latency variations among different experimental protocols based on the same type of ERP. Approach. We present a method to analyze and compensate for the latency variations in BCI applications. The algorithm has been tested on two widely used ERPs (P300 and observation error potentials), in three experimental protocols in each case. We report the ERP analysis and single-trial classification. Main results. The results obtained show that the designed experimental protocols significantly affect the latency of the recorded potentials but not the amplitudes. Significance. These results show how the use of latency-corrected data can be used to generalize the BCIs, reducing the calibration time when facing a new experimental protocol.

Transcriptome difference and potential crosstalk between liver and mammary tissue in mid-lactation primiparous dairy cows.

PubMed

Bu, Dengpan; Bionaz, Massimo; Wang, Mengzhi; Nan, Xuemei; Ma, Lu; Wang, Jiaqi

2017-01-01

Liver and mammary gland are among the most important organs during lactation in dairy cows. With the purpose of understanding both the different and the complementary roles and the crosstalk of those two organs during lactation, a transcriptome analysis was performed on liver and mammary tissues of 10 primiparous dairy cows in mid-lactation. The analysis was performed using a 4×44K Bovine Agilent microarray chip. The transcriptome difference between the two tissues was analyzed using SAS JMP Genomics using ANOVA with a false discovery rate correction (FDR). The analysis uncovered >9,000 genes differentially expressed (DEG) between the two tissues with a FDR<0.001. The functional analysis of the DEG uncovered a larger metabolic (especially related to lipid) and inflammatory response capacity in liver compared with mammary tissue while the mammary tissue had a larger protein synthesis and secretion, proliferation/differentiation, signaling, and innate immune system capacity compared with the liver. A plethora of endogenous compounds, cytokines, and transcription factors were estimated to control the DEG between the two tissues. Compared with mammary tissue, the liver transcriptome appeared to be under control of a large array of ligand-dependent nuclear receptors and, among endogenous chemical, fatty acids and bacteria-derived compounds. Compared with liver, the transcriptome of the mammary tissue was potentially under control of a large number of growth factors and miRNA. The in silico crosstalk analysis between the two tissues revealed an overall large communication with a reciprocal control of lipid metabolism, innate immune system adaptation, and proliferation/differentiation. In summary the transcriptome analysis confirmed prior known differences between liver and mammary tissue, especially considering the indication of a larger metabolic activity in liver compared with the mammary tissue and the larger protein synthesis, communication, and proliferative capacity in mammary tissue compared with the liver. Relatively novel is the indication by the data that the transcriptome of the liver is highly regulated by dietary and bacteria-related compounds while the mammary transcriptome is more under control of hormones, growth factors, and miRNA. A large crosstalk between the two tissues with a reciprocal control of metabolism and innate immune-adaptation was indicated by the network analysis that allowed uncovering previously unknown crosstalk between liver and mammary tissue for several signaling molecules.

Transcriptome difference and potential crosstalk between liver and mammary tissue in mid-lactation primiparous dairy cows

PubMed Central

Bu, Dengpan; Bionaz, Massimo; Wang, Mengzhi; Nan, Xuemei; Ma, Lu; Wang, Jiaqi

2017-01-01

Liver and mammary gland are among the most important organs during lactation in dairy cows. With the purpose of understanding both the different and the complementary roles and the crosstalk of those two organs during lactation, a transcriptome analysis was performed on liver and mammary tissues of 10 primiparous dairy cows in mid-lactation. The analysis was performed using a 4×44K Bovine Agilent microarray chip. The transcriptome difference between the two tissues was analyzed using SAS JMP Genomics using ANOVA with a false discovery rate correction (FDR). The analysis uncovered >9,000 genes differentially expressed (DEG) between the two tissues with a FDR<0.001. The functional analysis of the DEG uncovered a larger metabolic (especially related to lipid) and inflammatory response capacity in liver compared with mammary tissue while the mammary tissue had a larger protein synthesis and secretion, proliferation/differentiation, signaling, and innate immune system capacity compared with the liver. A plethora of endogenous compounds, cytokines, and transcription factors were estimated to control the DEG between the two tissues. Compared with mammary tissue, the liver transcriptome appeared to be under control of a large array of ligand-dependent nuclear receptors and, among endogenous chemical, fatty acids and bacteria-derived compounds. Compared with liver, the transcriptome of the mammary tissue was potentially under control of a large number of growth factors and miRNA. The in silico crosstalk analysis between the two tissues revealed an overall large communication with a reciprocal control of lipid metabolism, innate immune system adaptation, and proliferation/differentiation. In summary the transcriptome analysis confirmed prior known differences between liver and mammary tissue, especially considering the indication of a larger metabolic activity in liver compared with the mammary tissue and the larger protein synthesis, communication, and proliferative capacity in mammary tissue compared with the liver. Relatively novel is the indication by the data that the transcriptome of the liver is highly regulated by dietary and bacteria-related compounds while the mammary transcriptome is more under control of hormones, growth factors, and miRNA. A large crosstalk between the two tissues with a reciprocal control of metabolism and innate immune-adaptation was indicated by the network analysis that allowed uncovering previously unknown crosstalk between liver and mammary tissue for several signaling molecules. PMID:28291785

Introduction of a method for presenting health-based impacts of the emission from products, based on emission measurements of materials used in manufacturing of the products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jørgensen, Rikke Bramming, E-mail: rikke.jorgensen@iot.ntnu.no

A method for presenting the health impact of emissions from furniture is introduced, which could be used in the context of environmental product declarations. The health impact is described by the negative indoor air quality potential, the carcinogenic potential, the mutagenic and reprotoxic potential, the allergenic potential, and the toxicological potential. An experimental study of emissions from four pieces of furniture is performed by testing both the materials used for production of the furniture and the complete piece of furniture, in order to compare the results gained by adding emissions of material with results gained from testing the finished piecemore » of furniture. Calculating the emission from a product based on the emission from materials used in the manufacture of the product is a new idea. The relation between calculated results and measured results from the same products differ between the four pieces of furniture tested. Large differences between measured and calculated values are seen for leather products. More knowledge is needed to understand why these differences arise. Testing materials allows us to compare different suppliers of the same material. Four different foams and three different timber materials are tested, and the results vary between materials of the same type. If the manufacturer possesses this type of knowledge of the materials from the subcontractors it could be used as a selection criterion according to production of low emission products. -- Highlights: • A method for presenting health impact of emissions is introduced. • An experimental study of emissions from four pieces of furniture is performed. • Health impact is calculated based on sum of contribution from the materials used. • Calculated health impact is compared to health impact of the manufactured product. • The results show that health impact could be useful in product development and for presentation in EPDs.« less

Recent developments for the Large Binocular Telescope Guiding Control Subsystem

NASA Astrophysics Data System (ADS)

Golota, T.; De La Peña, M. D.; Biddick, C.; Lesser, M.; Leibold, T.; Miller, D.; Meeks, R.; Hahn, T.; Storm, J.; Sargent, T.; Summers, D.; Hill, J.; Kraus, J.; Hooper, S.; Fisher, D.

2014-07-01

The Large Binocular Telescope (LBT) has eight Acquisition, Guiding, and wavefront Sensing Units (AGw units). They provide guiding and wavefront sensing capability at eight different locations at both direct and bent Gregorian focal stations. Recent additions of focal stations for PEPSI and MODS instruments doubled the number of focal stations in use including respective motion, camera controller server computers, and software infrastructure communicating with Guiding Control Subsystem (GCS). This paper describes the improvements made to the LBT GCS and explains how these changes have led to better maintainability and contributed to increased reliability. This paper also discusses the current GCS status and reviews potential upgrades to further improve its performance.

How Project Managers Really Manage: An Indepth Look at Some Managers of Large, Complex NASA Projects

NASA Technical Reports Server (NTRS)

Mulenburg, Gerald M.; Impaeilla, Cliff (Technical Monitor)

2000-01-01

This paper reports on a research study by the author that examined ten contemporary National Aeronautics and Space Administration (NASA) complex projects. In-depth interviews with the project managers of these projects provided qualitative data about the inner workings of the project and the methodologies used in establishing and managing the projects. The inclusion of a variety of space, aeronautics, and ground based projects from several different NASA research centers helped to reduce potential bias in the findings toward any one type of project, or technical discipline. The findings address the participants and their individual approaches. The discussion includes possible implications for project managers of other large, complex, projects.

Explaining sex differences in reactions to relationship infidelities: comparisons of the roles of sex, gender, beliefs, attachment, and sociosexual orientation.

PubMed

Brase, Gary L; Adair, Lora; Monk, Kale

2014-02-04

To the extent that sex differences are mediated by mechanisms such as sex-roles and beliefs, individual differences in these more proximate traits should account for significant portions of relevant sex differences. Differences between women and men in reactions to sexual and emotional infidelity were assessed in a large sample of participants (n = 477), and these target reactions were evaluated as a function of many potential proximate mediators (infidelity implications beliefs, gender-role beliefs, interpersonal trust, attachment style, sociosexuality, and culture of honor beliefs) and as a function of participant sex. Results found a consistent sex difference that was not mediated by any other variables, although a handful of other variables were related to male, but not female, individual differences. These findings suggest particularly promising directions for future research on integrating evolutionarily based sex differences and proximate individual differences.

Exact dynamics of a one dimensional Bose gas in a periodic time-dependent harmonic trap

NASA Astrophysics Data System (ADS)

Scopa, Stefano; Unterberger, Jéremie; Karevski, Dragi

2018-05-01

We study the unitary dynamics of a 1D gas of hard-core bosons trapped into a harmonic potential which varies periodically in time with frequency . Such periodic systems can be classified into orbits of different monodromies corresponding to two different physical situations, namely the case in which the bosonic cloud remains stable during the time-evolution and the case where it turns out to be unstable. In the present work we derive in the large particle number limit exact results for the stroboscopic evolution of the energy and particle densities in both physical situations.

A political analysis of corporate drug donations: the example of Malarone in Kenya.

PubMed

Shretta, R; Walt, G; Brugha, R; Snow, R

2001-06-01

This paper describes the introduction of the Malarone Donation Programme in KENYA: Using a policy analysis approach it illustrates the political nature of donation programmes and how they are affected by a large and varied group of national, regional and international stakeholders, with different levels of influence and experience. The paper shows that interaction between these different groups may affect the development and implementation of the donation programme. It ends by raising some more general questions about public/private partnerships and corporate donation programmes, and their potential impact on national drug policies.

Mapping human brain networks with cortico-cortical evoked potentials

PubMed Central

Keller, Corey J.; Honey, Christopher J.; Mégevand, Pierre; Entz, Laszlo; Ulbert, Istvan; Mehta, Ashesh D.

2014-01-01

The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex. PMID:25180306

Full-potential modeling of blade-vortex interactions

NASA Technical Reports Server (NTRS)

Jones, H. E.; Caradonna, F. X.

1986-01-01

A comparison is made of four different models for predicting the unsteady loading induced by a vortex passing close to an airfoil. (1) The first model approximates the vortex effect as a change in the airfoil angle of attack. (2) The second model is related to the first but, instead of imposing only a constant velocity on the airfoil, the distributed effect of the vortex is computed and used. This is analogous to a lifting surface method. (3) The third model is to specify a branch cut discontinuity in the potential field. The vortex is modeled as a jump in potential across the branch cut, the edge of which represents the center of the vortex. (4) The fourth method models the vortex expressing the potential as the sum of a known potential due to the vortex and an unknown perturbation due to the airfoil. The purpose of the current study is to investigate the four vortex models described above and to determine their relative merits and suitability for use in large three-dimensional codes.

Barrier tunneling of the loop-nodal semimetal in the hyperhoneycomb lattice

NASA Astrophysics Data System (ADS)

Guan, Ji-Huan; Zhang, Yan-Yang; Lu, Wei-Er; Xia, Yang; Li, Shu-Shen

2018-05-01

We theoretically investigate the barrier tunneling in the 3D model of the hyperhoneycomb lattice, which is a nodal-line semimetal with a Dirac loop at zero energy. In the presence of a rectangular potential, the scattering amplitudes for different injecting states around the nodal loop are calculated, by using analytical treatments of the effective model, as well as numerical simulations of the tight binding model. In the low energy regime, states with remarkable transmissions are only concentrated in a small range around the loop plane. When the momentum of the injecting electron is coplanar with the nodal loop, nearly perfect transmissions can occur for a large range of injecting azimuthal angles if the potential is not high. For higher potential energies, the transmission shows a resonant oscillation with the potential, but still with peaks being perfect transmissions that do not decay with the potential width. These strikingly robust transports of the loop-nodal semimetal can be approximately explained by a momentum dependent Dirac Hamiltonian.

Attract them anyway: benefits of large, showy flowers in a highly autogamous, carnivorous plant species

PubMed Central

Salces-Castellano, A.; Paniw, M.; Casimiro-Soriguer, R.; Ojeda, F.

2016-01-01

Reproductive biology of carnivorous plants has largely been studied on species that rely on insects as pollinators and prey, creating potential conflicts. Autogamous pollination, although present in some carnivorous species, has received less attention. In angiosperms, autogamous self-fertilization is expected to lead to a reduction in flower size, thereby reducing resource allocation to structures that attract pollinators. A notable exception is the carnivorous pyrophyte Drosophyllum lusitanicum (Drosophyllaceae), which has been described as an autogamous selfing species but produces large, yellow flowers. Using a flower removal and a pollination experiment, we assessed, respectively, whether large flowers in this species may serve as an attracting device to prey insects or whether previously reported high selfing rates for this species in peripheral populations may be lower in more central, less isolated populations. We found no differences between flower-removed plants and intact, flowering plants in numbers of prey insects trapped. We also found no indication of reduced potential for autogamous reproduction, in terms of either seed set or seed size. However, our results showed significant increases in seed set of bagged, hand-pollinated flowers and unbagged flowers exposed to insect visitation compared with bagged, non-manipulated flowers that could only self-pollinate autonomously. Considering that the key life-history strategy of this pyrophytic species is to maintain a viable seed bank, any increase in seed set through insect pollinator activity would increase plant fitness. This in turn would explain the maintenance of large, conspicuous flowers in a highly autogamous, carnivorous plant. PMID:26977052

The role of the large-scale coronal magnetic field in the eruption of prominence/cavity systems

NASA Astrophysics Data System (ADS)

de Toma, G.; Gibson, S. E.; Fan, Y.; Torok, T.

2013-12-01

Prominence/cavity systems are large-scale coronal structures that can live for many weeks and even months and often end their life in the form of large coronal eruptions. We investigate the role of the surrounding ambient coronal field in stabilizing these systems against eruption. In particular, we examine the extent to which the decline with height of the external coronal magnetic field influences the evolution of these coronal systems and their likelihood to erupt. We study prominence/cavity systems during the rising phase of cycle 24 in 2010-2013, when a significant number of CMEs were associated with polar crown or large filament eruptions. We use EUV observations from SDO/AIA to identify stable and eruptive coronal cavities, and SDO/HMI magnetograms as boundary conditions to PFSS extrapolation to derive the ambient coronal field. We compute the decay index of the potential field for the two groups and find that systematic differences exist between eruptive and non-eruptive systems.

Geostatistics - a tool applied to the distribution of Legionella pneumophila in a hospital water system.

PubMed

Laganà, Pasqualina; Moscato, Umberto; Poscia, Andrea; La Milia, Daniele Ignazio; Boccia, Stefania; Avventuroso, Emanuela; Delia, Santi

2015-01-01

Legionnaires' disease is normally acquired by inhalation of legionellae from a contaminated environmental source. Water systems of large buildings, such as hospitals, are often contaminated with legionellae and therefore represent a potential risk for the hospital population. The aim of this study was to evaluate the potential contamination of Legionella pneumophila (LP) in a large hospital in Italy through georeferential statistical analysis to assess the possible sources of dispersion and, consequently, the risk of exposure for both health care staff and patients. LP serogroups 1 and 2-14 distribution was considered in the wards housed on two consecutive floors of the hospital building. On the basis of information provided by 53 bacteriological analysis, a 'random' grid of points was chosen and spatial geostatistics or FAIk Kriging was applied and compared with the results of classical statistical analysis. Over 50% of the examined samples were positive for Legionella pneumophila. LP 1 was isolated in 69% of samples from the ground floor and in 60% of sample from the first floor; LP 2-14 in 36% of sample from the ground floor and 24% from the first. The iso-estimation maps show clearly the most contaminated pipe and the difference in the diffusion of the different L. pneumophila serogroups. Experimental work has demonstrated that geostatistical methods applied to the microbiological analysis of water matrices allows a better modeling of the phenomenon under study, a greater potential for risk management and a greater choice of methods of prevention and environmental recovery to be put in place with respect to the classical statistical analysis.

Land surface temperature as potential indicator of burn severity in forest Mediterranean ecosystems

NASA Astrophysics Data System (ADS)

Quintano, C.; Fernández-Manso, A.; Calvo, L.; Marcos, E.; Valbuena, L.

2015-04-01

Forest fires are one of the most important causes of environmental alteration in Mediterranean countries. Discrimination of different degrees of burn severity is critical for improving management of fire-affected areas. This paper aims to evaluate the usefulness of land surface temperature (LST) as potential indicator of burn severity. We used a large convention-dominated wildfire, which occurred on 19-21 September, 2012 in Northwestern Spain. From this area, a 1-year series of six LST images were generated from Landsat 7 Enhanced Thematic Mapper (ETM+) data using a single channel algorithm. Further, the Composite Burn Index (CBI) was measured in 111 field plots to identify the burn severity level (low, moderate, and high). Evaluation of the potential relationship between post-fire LST and ground measured CBI was performed by both correlation analysis and regression models. Correlation coefficients were higher in the immediate post-fire LST images, but decreased during the fall of 2012 and increased again with a second maximum value in summer, 2013. A linear regression model between post-fire LST and CBI allowed us to represent spatially predicted CBI (R-squaredadj > 85%). After performing an analysis of variance (ANOVA) between post-fire LST and CBI, a Fisher's least significant difference test determined that two burn severity levels (low-moderate and high) could be statistically distinguished. The identification of such burn severity levels is sufficient and useful to forest managers. We conclude that summer post-fire LST from moderate resolution satellite data may be considered as a valuable indicator of burn severity for large fires in Mediterranean forest ecosytems.

Variation in mating system among birds: ecological basis revealed by hierarchical comparative analysis of mate desertion

PubMed Central

Owens, I. P. F.; Bennett, P. M.

1997-01-01

Since most bird species are socially monogamous, variation among species in social mating systems is determined largely by variation in the frequency of mate desertion. Mate desertion is expected to occur when the benefits, in terms of additional reproductive opportunities, outweigh the costs, in terms of reduced reproductive success from the present brood. However, despite much research, the relative importance of costs and benefits in explaining mating system variation is not well understood. Here, we investigate this problem using a comparative method. We analyse changes in the frequency of mate desertion at different phylogenetic levels. Differences between orders and families in the frequency of desertion are negatively associated with changes in the potential costs of desertion, but are not associated with changes in the potential benefits of desertion. Conversely, differences among genera and species in the frequency of desertion are positively associated with increases in the potential benefits of desertion, but not with changes in the potential costs of desertion. Hence, we suggest that mate desertion in birds originates through a combination of evolutionary predisposition and ecological facilitation. In particular, ancient changes in life-history strategy determine the costs of desertion and predispose certain lineages to polygamy, while contemporary changes in the distribution of resources determine the benefits of desertion and thereby the likelihood that polygamy will be viable within these lineages. Thus, monogamy can arise via two very different evolutionary pathways. Groups such as albatrosses (Procellariidae) are constrained to social monogamy by the high cost to desertion, irrespective of the potential benefits. However, in groups such as the accentors (Prunellidae), which are predisposed to desertion, monogamy occurs only when the benefits of desertion are very limited. These conclusions emphasise the additional power which a hierarchical approach contributes to the modern comparative method.

Characterisation of RPLC columns packed with porous sub-2 microm particles.

PubMed

Petersson, Patrik; Euerby, Melvin R

2007-08-01

Eight commercially available sub-2 microm octadecyl silane columns (C18 columns) have been characterised by the Tanaka protocol. The columns can be grouped into two groups that display large differences in selectivity and peak shape due to differences in hydrophobicity, degree of surface coverage and silanol activity. Measurements of particle size distributions were made using automated microscopy and electrical sensing zone measurements. Only a weak correlation could be found between efficiency and particle size. Large differences in column backpressure were observed. These differences are not related to particle size distribution. A more likely explanation is differences in packing density. In order to take full advantage of 100-150 mm columns packed with sub-2 microm particles, it is often necessary to employ not only an elevated pressure but also an elevated temperature. A comparison between columns packed with sub-2, 3 and 5 microm versions of the same packing indicates potential method transferability problems for several of the columns due to selectivity differences. Currently, the best alternative for fast high-resolution LC is the use of sub-2 microm particles in combination with elevated pressure and temperature. However, as shown in this study additional efforts are needed to improve transferability as well as column performance.