6,200 research outputs found
Hot Routes: Developing a New Technique for the Spatial Analysis of Crime
The use of hotspot mapping techniques such as KDE to represent the geographical spread of linear events can be problematic. Network-constrained data (for example transport-related crime) require a different approach to visualize concentration. We propose a methodology called Hot Routes, which measures the risk distribution of crime along a linear network by calculating the rate of crimes per section of road. This method has been designed for everyday crime analysts, and requires only a Geographical Information System (GIS), and suitable data to calculate. A demonstration is provided using crime data collected from London bus routes
Algorithms versus architectures for computational chemistry
The algorithms employed are computationally intensive and, as a result, increased performance (both algorithmic and architectural) is required to improve accuracy and to treat larger molecular systems. Several benchmark quantum chemistry codes are examined on a variety of architectures. While these codes are only a small portion of a typical quantum chemistry library, they illustrate many of the computationally intensive kernels and data manipulation requirements of some applications. Furthermore, understanding the performance of the existing algorithm on present and proposed supercomputers serves as a guide for future programs and algorithm development. The algorithms investigated are: (1) a sparse symmetric matrix vector product; (2) a four index integral transformation; and (3) the calculation of diatomic two electron Slater integrals. The vectorization strategies are examined for these algorithms for both the Cyber 205 and Cray XMP. In addition, multiprocessor implementations of the algorithms are looked at on the Cray XMP and on the MIT static data flow machine proposed by DENNIS
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The effect of elevated hydrostatic pressure on the spectral absorption of deep-sea fish visual pigments
The effect of hydrostatic pressure (0.1-54 MPa, equivalent to pressures experienced by fish from the ocean's surface to depths of ca. 5400 m) on visual pigment absorption spectra was investigated for rod visual pigments extracted from the retinae of 12 species of deep-sea fish of diverse phylogeny and habitat. The wavelength of peak absorption (λmax) was shifted to longer wavelengths by an average of 1.35 nm at 40 MPa (a pressure approximately equivalent to average ocean depth) relative to measurements made at one atmosphere (ca. 0.1 MPa), but with little evidence of a change in absorbance at the λmax. We conclude that previousλ max measurements of deep-sea fish visual pigments, made at a pressure close to 0.1 MPa, provide a good indication ofλ max values at higher pressures when considering the ecology of vision in the deep-sea. Although not affecting the spectral sensitivity of the animal to any important degree, the observed shift inλ max may be of interest in the context of understanding opsin-chromophore interaction and spectral tuning of visual pigments
Preserving the Memory of those Perilous Times: Archaeology of a Civil War Prison in Blackshear, Georgia
In the closing months of 1864 Confederate prison authorities were forced to evacuate the large stockade prisoner of war (POW) camps at Millen and Andersonville, Georgia in the face of General Sherman’s ‘March to the Sea’. While attempting to evade Union forces, approximately 5,000 POWs were sent along the Atlantic and Gulf railroad in south east Georgia, stopping just outside of the town of Blackshear. For three weeks prisoners and guards camped along a small tributary of the Alabaha River with only a few steaks to mark a deadline between them. No formal prison enclosure or fortifications were constructed and while escapes were frequent the majority of the prisoners would endure their stay before continuing down the line to Thomasville. In this thesis, I continue the investigation of site 9PR26 by further delineating the boundaries with metal detection survey. By examining the artifact patterning I attempt to determine the general layout of the camp and why this particular location was chosen as the site of a makeshift prison by its commander
Theoretical dissociation energies for ionic molecules
Ab initio calculations at the self-consistent-field and singles plus doubles configuration-interaction level are used to determine accurate spectroscopic parameters for most of the alkali and alkaline-earth fluorides, chlorides, oxides, sulfides, hydroxides, and isocyanides. Numerical Hartree-Fock (NHF) calculations are performed on selected systems to ensure that the extended Slater basis sets employed for the diatomic systems are near the Hartree-Fock limit. Extended Gaussian basis sets of at least triple-zeta plus double polarization equality are employed for the triatomic system. With this model, correlation effects are relatively small, but invariably increase the theoretical dissociation energies. The importance of correlating the electrons on both the anion and the metal is discussed. The theoretical dissociation energies are critically compared with the literature to rule out disparate experimental values. Theoretical (sup 2)Pi - (sup 2)Sigma (sup +) energy separations are presented for the alkali oxides and sulfides
NICMOS Imaging of the Dusty Microjansky Radio Source VLA J123642+621331 at z = 4.424
We present the discovery of a radio galaxy at a likely redshift of z = 4.424
in one of the flanking fields of the Hubble Deep Field. Radio observations with
the VLA and MERLIN centered on the HDF yielded a complete sample of microjansky
radio sources, of which about 20% have no optical counterpart to I < 25 mag. In
this Letter, we address the possible nature of one of these sources, through
deep HST NICMOS images in the F110W (J) and F160W (H) filters. VLA
J123642+621331 has a single emission line at 6595-A, which we identify with
Lyman-alpha at z = 4.424. We argue that this faint (H = 23.9 mag), compact (r =
0.2 arcsec), red (I - K = 2.0) object is most likely a dusty, star-forming
galaxy with an embedded active nucleus.Comment: Accepted for publication in Astrophysical Journal Letters. 11 pages,
4 figures, uses aastex v5.0 and psfi
Effect of a standardised dietary restriction protocol on multiple laboratory strains of Drosophila melanogaster
Background:
Outcomes of lifespan studies in model organisms are particularly susceptible to variations in technical procedures. This is especially true of dietary restriction, which is implemented in many different ways among laboratories.
Principal Findings:
In this study, we have examined the effect of laboratory stock maintenance, genotype differences and microbial infection on the ability of dietary restriction (DR) to extend life in the fruit fly Drosophila melanogaster. None of these factors block the DR effect.
Conclusions:
These data lend support to the idea that nutrient restriction genuinely extends lifespan in flies, and that any mechanistic discoveries made with this model are of potential relevance to the determinants of lifespan in other organisms
Quantitying the Effects of Traffic Calming on Emissions Using on-road Measurement
The objective of this work was to determine the effect of
one form of traffic calming on emissions. Traffic calming
is aimed at reducing average vehicle speeds, especially
in residential neighborhoods, often using physical road
obstructions such as speed bumps, but it also results in
a higher number of acceleration/deceleration events
which in turn yield higher emissions. Testing was
undertaken by driving a warmed-up Euro-1 spark ignition
passenger car over a set of speed bumps on a level
road, and then comparing the emissions output to a noncalmed
level road negotiated smoothly at a similar
average speed. For the emissions measurements, a
novel method was utilized, whereby the vehicle was
fitted with a portable Fourier Transform Infrared (FTIR)
spectrometer, capable of measuring up to 51 different
components in real-time on the road. The results
showed that increases in emissions were much greater
than was previously reported by other researchers using
different techniques. When traffic-calmed results were
compared to a smooth non-calmed road, there were
substantial increases in CO2 (90%), CO (117%), NOx
(195%) and THC (148%). These results form the basis
for a good argument against traffic calming using speed
bumps, especially for aggressive drivers. Slowing traffic
down with speed restrictions enforced by speed
cameras is a more environmentally friendly option
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