8,842 research outputs found
Cost reductions in nickel-hydrogen battery
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
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
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
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
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
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
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
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)
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
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
- …