8,842 research outputs found

    Cost reductions in nickel-hydrogen battery

    Get PDF
    Significant progress was made toward the development of a commercially marketable hydrogen nickel oxide battery. The costs projected for this battery are remarkably low when one considers where the learning curve is for commercialization of this system. Further developmental efforts on this project are warranted as the H2/NiO battery is already cost competitive with other battery systems

    Fluctuation-dissipation ratios in the dynamics of self-assembly

    Full text link
    We consider two seemingly very different self-assembly processes: formation of viral capsids, and crystallization of sticky discs. At low temperatures, assembly is ineffective, since there are many metastable disordered states, which are a source of kinetic frustration. We use fluctuation-dissipation ratios to extract information about the degree of this frustration. We show that our analysis is a useful indicator of the long term fate of the system, based on the early stages of assembly.Comment: 8 pages, 6 figure

    Behaviour of dairy cows on organic and non-organic farms

    Get PDF
    There is an increasing number of organic dairy farms in the UK. The aim of this study is to compare behaviour of dairy cows on organic and non-organic farms. Twenty organic and 20 non-organic farms throughout the UK were visited over two winters (2004/05 and 2005/06). Organic and non-organic farms were paired for housing type, herd size, milk production traits and location. The number of cows feeding was counted every fifteen minutes for 4.5 h after new feed was available post morning milking. Behaviour at the feed-face was recorded for 60 minutes and aggressive interactions between cows were quantified. Farm type had no effect on numbers of cows feeding. There were more interactions between cows feeding at open feed-faces compared to head-bale barriers. At open feed-faces, there were more interactions on organic farms than non-organic. It is possible that organic cows were hungrier than non-organic cows after the arrival of new feed

    The Fayet-Iliopoulos D-term and its renormalisation in the MSSM

    Get PDF
    We consider the renormalisation of the Fayet-Iliopoulos D-term in a softly-broken supersymmetric gauge theory with a non-simple gauge group containing an abelian factor, and present the associated beta-function through three loops. We also include in an appendix the result for several abelian factors. We specialise to the case of the minimal supersymmetric standard model (MSSM), and investigate the behaviour of the Fayet-Iliopoulos coupling for various boundary conditions at the unification scale. We focus particularly on the case of non-standard soft supersymmetry breaking couplings, for which the Fayet-Iliopoulos coupling evolves significantly between the unification scale and the weak scale.Comment: 18 pages, Revtex, 2 figures. Expanded version including general results for gauge groups with several abelian factors. Minor typos correcte

    The automated Materials Handling Support System (463L): a modern cargo system for the Military Air Transport Service

    Get PDF
    Air cargo transportation has assumed a major role in the defense readiness posture of the United States military service since World War II. The airlift of cargo outside the continental limits of the United States is provided by the Air Force's Military Air Transport Service (MATS) for all of the military services. MATS cargo services were recently modernized by introduction of an automated materials handling system labeled the Materials Handling Support System (4631). The evolution of this system in MATS is discussed from inception through performance evaluation, encompassing the areas of equipment identification, implementation and operational policies and procedures. The effect of the 4631 System on Naval Logistics Support is evaluated by synopsizing reports and assessments emanating from Navy officials involved in transportation management and air cargo functions.http://www.archive.org/details/automatedmateria00konoLieutenant, United States NavyLieutenant, United States NavyApproved for public release; distribution is unlimited

    Universality in chaotic quantum transport: The concordance between random matrix and semiclassical theories

    Get PDF
    Electronic transport through chaotic quantum dots exhibits universal, system independent, properties, consistent with random matrix theory. The quantum transport can also be rooted, via the semiclassical approximation, in sums over the classical scattering trajectories. Correlations between such trajectories can be organized diagrammatically and have been shown to yield universal answers for some observables. Here, we develop the general combinatorial treatment of the semiclassical diagrams, through a connection to factorizations of permutations. We show agreement between the semiclassical and random matrix approaches to the moments of the transmission eigenvalues. The result is valid for all moments to all orders of the expansion in inverse channel number for all three main symmetry classes (with and without time reversal symmetry and spin-orbit interaction) and extends to nonlinear statistics. This finally explains the applicability of random matrix theory to chaotic quantum transport in terms of the underlying dynamics as well as providing semiclassical access to the probability density of the transmission eigenvalues.Comment: Refereed version. 5 pages, 4 figure

    Mechanisms of kinetic trapping in self-assembly and phase transformation

    Get PDF
    In self-assembly processes, kinetic trapping effects often hinder the formation of thermodynamically stable ordered states. In a model of viral capsid assembly and in the phase transformation of a lattice gas, we show how simulations in a self-assembling steady state can be used to identify two distinct mechanisms of kinetic trapping. We argue that one of these mechanisms can be adequately captured by kinetic rate equations, while the other involves a breakdown of theories that rely on cluster size as a reaction coordinate. We discuss how these observations might be useful in designing and optimising self-assembly reactions

    Dual Interpretations of Pion Clouds at RHIC

    Get PDF
    A gauge theory of pions interacting with rho-mesons at elevated temperatures is used to calculate the pressure in a hot pion gas. No reference is made to the pion's status as a QCD Goldstone boson. The role of the pion is merely that of a carrier of an SU(2) symmetry, gauged to create a vector-meson interaction, the rho playing the role of the interacting vector particle. The results are in rough agreement with much more elaborate calculations, both of the purely hadronic variety, and those that invoke quark-gluon degrees of freedom. The quark-gluon and purely hadronic calculations seemingly lead to very similar predictions which are in accord with receent data from RHIC. The results motivate the question as to whether the two descriptions are dual to each other in the sense of being alternate models, each sufficient to explain the observed data.Comment: 11 pages, 4 figures (2 eps files, 1 ps file) + a figure that uses metafont package feynmf, also forwarded. Open with "latex feynmf.ins". See http://www.ctan.org/tex-archive/help/Catalogue/entries/feynmf.html 9/6/06 replaced figure 2 with scaled version of sam

    Visible and near infrared observation on the Global Aerosol Backscatter Experiment (GLOBE)

    Get PDF
    The Global Aerosol Backscatter Experiment (GLOBE) was intended to provide data on prevailing values of atmospheric backscatter cross-section. The primary intent was predicting the performance of spaceborne lidar systems, most notably the Laser Atmospheric Wind Sounder (LAWS) for the Earth Observing System (EOS). The second and related goal was to understand the source and characteristics of atmospheric aerosol particles. From the GLOBE flights, extensive data was obtained on the structure of clouds and the marine planetary boundary layer. A notable result for all observations is the consistency of the large increases in the aerosol scattering ratio for the marine boundary layer. Other results are noted

    Lack of Brown-Headed Cowbird Nest Parasitism in a Short Grass Region

    Get PDF
    While conducting field work in Morton County, southwestern Kansas and Baca County, southeastern Colorado, during the period 27 May to 2 July 1997, we found 36 nests of seven bird species. Nests were not searched for systematically, but were found coincidentally as data were collected along transects during research investigating the breeding bird and plant communities of black-tailed prairie dog (Cynomys ludovicianus) colonies and noncolonized shortgrass prairie (Winter 1999). Low densities of the brown-headed cowbird in our study region, which is characterized by a semi-arid climate, might be a consequence of host populations that exhibit extreme temporal and spatial variability in response to the climatic variability of these regions (Wiens 1974, Cody 1985, Winter et al. 2003). As host populations vary greatly in time and space over large areas on the western Great Plains (Wiens 1974, Cody 1985), perhaps the brown-headed cowbird is simply unable to effectively respond to host population changes
    corecore