205,760 research outputs found
The Coherence Problem: Mapping the Theory and Delivery of Infrastructure Resilience Across Concept, Form, Function, and Experienced Value
In this contribution we explore the interface between the functional characteristics of infrastructures as artefacts and
social need supplier. Specifically we are concerned with the ways in which infrastructure performance measures are
articulated and assessed and whether there are incongruities between the technical and broader, social goals which
infrastructure systems are intended to aspire to. Our analysis involves comparing and contrasting system design
and performance metrics across the technical — social boundary, generating new insights for those tasked with the
design and operation of networked infrastructures. The assessment delivered in the following sections is inherently
interdisciplinary and cross-sectoral in nature, bringing thinking from the social and environmental sciences together
with contributions from mathematics and engineering to offer a commentary which is relevant to all types of physical
infrastructure
The vertical structure of Jupiter's equatorial and tropical regions
The equatorial and tropical regions of Jupiter are presently treated in light of an inhomogeneous atmospheric model that encompasses both polarizing aerosols and methane gas, in keeping with Pioneer polarimetry and photometry data as well as the methane band data obtained by West (1979). The relative strengths of weak and strong methane bands are addressed by a two-cloud model with overlying stratospheric haze. For all the regions considered, the best fit for polarization measurements is a negatively polarizing ammonia cloud beneath a positively polarizing haze. Unlike the nearby features, the equatorial region and the Great Red Spot have a negative polarization at 80-deg phase angle, implying less gas above the clouds in these regions
Recommended from our members
A numerical study of heat flow in an elliptic cylinder with interior derivative boundary conditions
Dynamical theory on low energy electron diffraction Final report
Bethe theory of low energy electron diffraction applied to computation of diffracted beam intensity as function of wavelengt
Laser surface interactions - Creation and detection of atomically clean surfaces Semiannual report, Oct. 1, 1966 - Mar. 31, 1967
Low energy electron diffraction method of identifying atomically clean surface after laser surface interactio
A simulator study of the interaction of pilot workload with errors, vigilance, and decisions
A full mission simulation of a civil air transport scenario that had two levels of workload was used to observe the actions of the crews and the basic aircraft parameters and to record heart rates. The results showed that the number of errors was very variable among crews but the mean increased in the higher workload case. The increase in errors was not related to rise in heart rate but was associated with vigilance times as well as the days since the last flight. The recorded data also made it possible to investigate decision time and decision order. These also varied among crews and seemed related to the ability of captains to manage the resources available to them on the flight deck
Viscous relaxation and collective oscillations in a trapped Fermi gas near the unitarity limit
The viscous relaxation time of a trapped two-component gas of fermions in its
normal phase is calculated as a function of temperature and scattering length,
with the collision probability being determined by an energy-dependent s-wave
cross section. The result is used for calculating the temperature dependence of
the frequency and damping of collective modes studied in recent experiments,
starting from the kinetic equation for the fermion distribution function with
mean-field effects included in the streaming terms.Comment: 10 pages, 9 figures; proof version, corrected typo in Eq. (23);
accepted for publication in PR
Study made of interaction between sound fields and structural vibrations
Study analyzes structural vibrations and the interactions between them and sound fields. It outlines a conceptual framework to analyze the vibrations of systems and their interactions, incorporating the results of earlier studies and establishing a unified basis for continuing research
Using parallel computation to improve Independent Metropolis--Hastings based estimation
In this paper, we consider the implications of the fact that parallel
raw-power can be exploited by a generic Metropolis--Hastings algorithm if the
proposed values are independent. In particular, we present improvements to the
independent Metropolis--Hastings algorithm that significantly decrease the
variance of any estimator derived from the MCMC output, for a null computing
cost since those improvements are based on a fixed number of target density
evaluations. Furthermore, the techniques developed in this paper do not
jeopardize the Markovian convergence properties of the algorithm, since they
are based on the Rao--Blackwell principles of Gelfand and Smith (1990), already
exploited in Casella and Robert (1996), Atchade and Perron (2005) and Douc and
Robert (2010). We illustrate those improvements both on a toy normal example
and on a classical probit regression model, but stress the fact that they are
applicable in any case where the independent Metropolis-Hastings is applicable.Comment: 19 pages, 8 figures, to appear in Journal of Computational and
Graphical Statistic
Responses of a bacterial pathogen to phosphorus limitation of its aquatic invertebrate host
Host nutrition is thought to affect the establishment, persistence, and severity of pathogenic infections. Nutrient-deficient foods possibly benefit pathogens by constraining host immune function or benefit hosts by limiting parasite growth and reproduction. However, the effects of poor elemental food quality on a host's susceptibility to infection and disease have received little study. Here we show that the bacterial microparasite Pasteuria ramosa is affected by the elemental nutrition of its aquatic invertebrate host, Daphnia magna. We found that high food carbon : phosphorus (C: P) ratios significantly reduced infection rates of Pasteuria in Daphnia and led to lower within-host pathogen multiplication. In addition, greater virulent effects of bacterial infection on host reproduction were found in Daphnia-consuming P-deficient food. Poor Daphnia elemental nutrition thus reduced the growth and reproduction of its bacterial parasite, Pasteuria. The effects of poor host nutrition on the pathogen were further evidenced by Pasteuria's greater inhibition of reproduction in P-limited Daphnia. Our results provide strong evidence that elemental food quality can significantly influence the incidence and intensity of infectious disease in invertebrate hosts
- …