24,938 research outputs found
Aberrations of radio signals traversing the auroral ionosphere Semiannual analysis report, 1 Jul. 1968 - 31 Jan. 1969
Satellite observations of aberrations of radio signals traversing auroral ionosphere indicating decreasing trend in scintillation activit
Accounting for Seismic Risk in Financial Analysis of Property Investment
A methodology is presented for making property investment decisions using loss
analysis and the principles of decision analysis. It proposes that the investor choose among
competing investment alternatives on the basis of the certainty equivalent of their net asset value
which depends on the uncertain discounted future net income, uncertain discounted future
earthquake losses, initial equity and the investor’s risk tolerance. The earthquake losses are
modelled using a seismic vulnerability function, the site seismic hazard function, and an
assumption that strong shaking at a site follows a Poisson process. A building-specific
vulnerability approach, called assembly-based vulnerability, or ABV, is used. ABV involves a
simulation approach that includes dynamic structural analyses and damage analyses using
fragility functions and probability distributions on unit repair costs and downtimes for all
vulnerable structural and nonstructural components in a building. The methodology is
demonstrated using some results from a seven-storey reinforced-concrete hotel in Los Angeles
Offender and offence characteristics of school shooting incidents
School shootings are a concern due to their impact in the local community. This paper aimed to (a) establish frequent characteristics of the offender and offence, (b) explore the differences between offenders who are over the age of 18 years and those who are younger, and (c) consider the underlying themes of the offence characteristics. Data were collected on 28 cases through accessing resources such as West Law and case studies. The majority of the offenders were Caucasian and US citizens and suffered from depression. Their offences were primarily well planned, involved more than three deaths, and resulted in the offender committing suicide. Pearson’s chi-square test and Fisher’s exact test identified significant differences between the two age groups. Offenders who were 18 years of age or under were more likely to experience depression, be US citizens and be linked to the school. Additionally, offenders who were 18 years of age or under were more likely to have stolen their weapons and made threats prior to the incident. Smallest space analysis revealed four thematic regions in relation to the offence characteristics: making an impact, delivering a message, doing unrestrained activity, and targeting specific individuals. These findings have implications for risk assessment and furthering understanding.
Keywrods : school shooting; juvenile; offence characteristics; multidimensional scaling; school violenc
Modeling chemotaxis reveals the role of reversed phosphotransfer and a bi-functional kinase-phosphatase
Understanding how multiple signals are integrated in living cells to produce a balanced response is a major challenge in
biology. Two-component signal transduction pathways, such as bacterial chemotaxis, comprise histidine protein kinases
(HPKs) and response regulators (RRs). These are used to sense and respond to changes in the environment. Rhodobacter
sphaeroides has a complex chemosensory network with two signaling clusters, each containing a HPK, CheA. Here we
demonstrate, using a mathematical model, how the outputs of the two signaling clusters may be integrated. We use our
mathematical model supported by experimental data to predict that: (1) the main RR controlling flagellar rotation, CheY6, aided by its specific phosphatase, the bifunctional kinase CheA3, acts as a phosphate sink for the other RRs; and (2) a phosphorelay pathway involving CheB2 connects the cytoplasmic cluster kinase CheA3 with the polar localised kinase CheA2, and allows CheA3-P to phosphorylate non-cognate chemotaxis RRs. These two mechanisms enable the bifunctional kinase/phosphatase activity of CheA3 to integrate and tune the sensory output of each signaling cluster to produce a balanced response. The signal integration mechanisms identified here may be widely used by other bacteria, since like R. sphaeroides, over 50% of chemotactic bacteria have multiple cheA homologues and need to integrate signals from different
sources
Observation of discrete energy levels in a quantum confined system
Low temperature scanning tunneling microscope images and spectroscopic data
have been obtained on subnanometer size Pb clusters fabricated using the
technique of buffer layer assisted growth. Discrete energy levels were resolved
in current-voltage characteristics as current peaks rather than current steps.
Distributions of peak voltage spacings and peak current heights were consistent
with Wigner-Dyson and Porter-Thomas distributions respectively, suggesting the
relevance of random matrix theory to the description of the electronic
eigenstates of the clusters. The observation of peaks rather than steps in the
current-voltage characteristics is attributed to a resonant tunneling process
involving the discrete energy levels of the cluster, the tip, and the states at
the interface between the cluster and the substrate surface.Comment: 4 pages, 4 figure
The Cauchy convergence of T and P-approximant templates for test-mass Kerr binary systems
In this work we examine the Cauchy convergence of both post-Newtonian
(T-approximant) and re-summed post-Newtonian (P-approximant) templates for the
case of a test-mass orbiting a Kerr black hole along a circular equatorial
orbit. The Cauchy criterion demands that the inner product between the and
order approximation approaches unity, as we increase the order of
approximation. In previous works, it has been shown that we achieve greater
fitting factors and better parameter estimation using the P-approximant
templates for both Schwarzschild and Kerr black holes. In this work, we show
that the P-approximant templates also display a faster Cauchy convergence
making them a superior template to the standard post-Newtonian templates.Comment: 5 pages, Replaced with shortened published versio
MCMC Exploration of Supermassive Black Hole Binary Inspirals
The Laser Interferometer Space Antenna will be able to detect the inspiral
and merger of Super Massive Black Hole Binaries (SMBHBs) anywhere in the
Universe. Standard matched filtering techniques can be used to detect and
characterize these systems. Markov Chain Monte Carlo (MCMC) methods are ideally
suited to this and other LISA data analysis problems as they are able to
efficiently handle models with large dimensions. Here we compare the posterior
parameter distributions derived by an MCMC algorithm with the distributions
predicted by the Fisher information matrix. We find excellent agreement for the
extrinsic parameters, while the Fisher matrix slightly overestimates errors in
the intrinsic parameters.Comment: Submitted to CQG as a GWDAW-10 Conference Proceedings, 9 pages, 5
figures, Published Versio
Concept design and alternate arrangements of orbiter mid-deck habitability features
The evaluations and recommendations for habitability features in the space shuttle orbiter mid-deck are summarized. The orbiter mission plans, the mid-deck dimensions and baseline arrangements along with crew compliments and typical activities were defined. Female and male anthropometric data based on zero-g operations were also defined. Evaluations of baseline and alternate feasible concepts provided several recommendations which are discussed
Information filtering via Iterative Refinement
With the explosive growth of accessible information, expecially on the
Internet, evaluation-based filtering has become a crucial task. Various systems
have been devised aiming to sort through large volumes of information and
select what is likely to be more relevant. In this letter we analyse a new
ranking method, where the reputation of information providers is determined
self-consistently.Comment: 10 pages, 3 figures. Accepted for publication on Europhysics Letter
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