71,793 research outputs found
Calculation of accurate permanent dipole moments of the lowest states of heteronuclear alkali dimers using extended basis sets
The obtention of ultracold samples of dipolar molecules is a current
challenge which requires an accurate knowledge of their electronic properties
to guide the ongoing experiments. In this paper, we systematically investigate
the ground state and the lowest triplet state of mixed alkali dimers (involving
Li, Na, K, Rb, Cs) using a standard quantum chemistry approach based on
pseudopotentials for atomic core representation, gaussian basis sets, and
effective terms for core polarization effects. We emphasize on the convergence
of the results for permanent dipole moments regarding the size of the gaussian
basis set, and we discuss their predicted accuracy by comparing to other
theoretical calculations or available experimental values. We also revisit the
difficulty to compare computed potential curves among published papers, due to
the differences in the modelization of core-core interaction.Comment: accepted to J. Chem. Phy
Surface-material maps of Viking landing sites on Mars
Researchers mapped the surface materials at the Viking landing sites on Mars to gain a better understanding of the materials and rock populations at the sites and to provide information for future exploration. The maps extent to about 9 m in front of each lander and are about 15 m wide - an area comparable to the area of a pixel in high resolution Viking Orbiter images. The maps are divided into the near and far fields. Data for the near fields are from 1/10 scale maps, umpublished maps, and lander images. Data for the far fields are from 1/20 scale contour maps, contoured lander camera mosaics, and lander images. Rocks are located on these maps using stereometric measurements and the contour maps. Frequency size distribution of rocks and the responses of soil-like materials to erosion by engine exhausts during landings are discussed
The disappearing women: North West ICT project final report
Project Context
The Disappearing Women: Northwest ICT project was embarked upon to further understand why more women leave the sector than are being recruited, 36% of new ICT recruits in the UK (in the first quarter of 2002) were women, yet in the same period, women accounted for 46% of all leavers or âdisappearingâ women (The DTI Women in IT Champions report 2003, Grey and Healy 2004). This continuing trend shows a decline from 27% of women making up the ICT workforce in 1997 with a drop to 21% in 2004 (The DTI Women in IT Industry report 2005b). The number of women in the ICT sector remains disappointingly small considering that women make up around 50% of the total UK workforce and significantly this figure has gradually continued to fall despite numerous initiatives to attract more women into the sector (see Griffiths and Moore 2006 for a list of high profile âwomen in ICTâ initiatives).
The research teamâs first gender research project - Women in IT (WINIT) - ran for two years from January 2004 until March 2006 at the Information Systems Institute at The University of Salford and dealt solely with women who worked in the ICT sector in England. The WINIT Project via an online questionnaire and in-depth interviews gathered the stories and experiences of up to 500 participants and 19 interviewees respectively. The project enabled these womenâs voices to be heard but the research team were constantly aware that a certain part of the female ICT workforce - the âdisappearingâ women who had left ICT vowing never to return - had been overlooked and effectively silenced. It was these women who once found, may be able to facilitate a more in-depth understanding of why women were leaving the ICT sector. Having amassed skills and expertise, qualifications in ICT and crossed ICT recruitment barriers (DTI 2005a) the âdisappearingâ women for whatever reasons decided to change their career trajectories and leave the sector. What âchillyâ (Falkner 2004) workplaces, disinterested organisational cultures and indifferent working conditions had these women encountered that became determining factors in leaving the ICT sector? There has been little (if any) research conducted involving this specific cohort of women and The Disappearing Women: North West ICT (DW: NW ICT) project seeks to make a research contribution to what is a continuing statistical and symbolic under-representation of women in the ICT labour market.
The DW: NW ICT project was partly funded by the European Social Fund (ESF) from April 2006 until December 2006 under ESF Objective 3, Policy Field 5.1: Improving the Participation of Women. The DW: NW ICT project contributes research to priority 5 and its strategic objective to reduce the level of disadvantage faced by women in the labour market. The project was run in the Information Systems Group, Salford Business School of The University of Salford, Greater Manchester, UK.
The report is structured as follows. The first section presents the backdrop for the research, looking in general at women in the ICT labour market in England and then women leaving the ICT sector focussing on the North West of England and more explicitly women leaving ICT employment in the North West of England. The research aims of the project form the following section; they have been loosely classified in to two groupings, the push and pull factors that are contributing to the high attrition rate of women leaving ICT. The methodology follows with the route taken in how this âhard to reachâ target sample were finally located, once contacted the life history interview process and procedures adopted is explained in full. The vignettes of the âdisappearingâ women are included to allow the reader an opportunity to âget to knowâ these women a little more closely. Key themes that have naturally emerged throughout the interview data analysis process are presented, including hostilities in the ICT workplace, significant events and the process of leaving ICT workplaces and finally stories of the âappearingâ women and their current situations are heard. A discussion regarding the findings of the DW: NW ICT project concludes this report
Reply to "Comment on Evidence for the droplet picture of spin glasses"
Using Monte Carlo simulations (MCS) and the Migdal-Kadanoff approximation
(MKA), Marinari et al. study in their comment on our paper the link overlap
between two replicas of a three-dimensional Ising spin glass in the presence of
a coupling between the replicas. They claim that the results of the MCS
indicate replica symmetry breaking (RSB), while those of the MKA are trivial,
and that moderate size lattices display the true low temperature behavior. Here
we show that these claims are incorrect, and that the results of MCS and MKA
both can be explained within the droplet picture.Comment: 1 page, 1 figur
Recommended from our members
Entropy scaling based viscosity predictions for hydrocarbon mixtures and diesel fuels up to extreme conditions
An entropy scaling based technique using the Perturbed-Chain Statistical Associating Fluid Theory is described for predicting the viscosity of hydrocarbon mixtures and diesel fuels up to high temperatures and high pressures. The compounds found in diesel fuels or hydrocarbon mixtures are represented as a single pseudo-component. The model is not fit to viscosity data but is predictive up to high temperatures and pressures with input of only two calculated or measured mixture properties: the number averaged molecular weight and hydrogen to carbon ratio. Viscosity is predicted less accurately when the mixture contains high concentrations of iso-alkanes and cyclohexanes. However, it is shown that predictions for these mixtures are improved by fitting a third parameter to a single viscosity data point at a chosen reference state. For hydrocarbon mixtures, viscosity is predicted with average mean absolute percent deviations (MAPDs) of 12.2% using the two-parameter model and 7.3% using the three-parameter model from 293 to 353 K and up to 1000 bar. For two different diesel fuels, viscosity is predicted with an average MAPD of 21.4% using the two-parameter model and 9.4% using the three-parameter model from 323 to 423 K and up to 3500 bar
Theory of superradiant scattering of laser light from Bose-Einstein condensates
In a recent MIT experiment, a new form of superradiant Rayleigh scattering
was observed in Bose-Einstein condensates. We present a detailed theory of this
phenomena in which the directional dependence of the scattering rate and
condensate depletion lead to mode competition which is ultimately responsible
for superradiance. The nonlinear response of the system is highly sensitive to
initial quantum fluctuations which cause large run to run variations in the
observed superradiant pulses.Comment: Updated version with new figures,a numerical simulation with
realistic experimental parameters is now included. Featured in September 1999
Physics Today, in Search and Discovery sectio
Parallel Metric Tree Embedding based on an Algebraic View on Moore-Bellman-Ford
A \emph{metric tree embedding} of expected \emph{stretch~}
maps a weighted -node graph to a weighted tree with such that, for all ,
and
. Such embeddings are highly useful for designing
fast approximation algorithms, as many hard problems are easy to solve on tree
instances. However, to date the best parallel -depth algorithm that achieves an asymptotically optimal expected stretch of
requires
work and a metric as input.
In this paper, we show how to achieve the same guarantees using
depth and
work, where and is an arbitrarily small constant.
Moreover, one may further reduce the work to at the expense of increasing the expected stretch to
.
Our main tool in deriving these parallel algorithms is an algebraic
characterization of a generalization of the classic Moore-Bellman-Ford
algorithm. We consider this framework, which subsumes a variety of previous
"Moore-Bellman-Ford-like" algorithms, to be of independent interest and discuss
it in depth. In our tree embedding algorithm, we leverage it for providing
efficient query access to an approximate metric that allows sampling the tree
using depth and work.
We illustrate the generality and versatility of our techniques by various
examples and a number of additional results
An improved approach for flight readiness assessment
An improved methodology for quantitatively evaluating failure risk for a spaceflight system in order to assess flight readiness is presented. This methodology is of particular value when information relevant to failure prediction, including test experience and knowledge of parameters used in engineering analyses of failure phenomena, is limited. In this approach, engineering analysis models that characterize specific failure modes based on the physics and mechanics of the failure phenomena are used in a prescribed probabilistic structure to generate a failure probability distribution that is modified by test and flight experience in a Bayesian statistical procedure. The probabilistic structure and statistical methodology are generally applicable to any failure mode for which quantitative engineering analysis can be employed to characterize the failure phenomenon and are particularly well suited for use under the constraints on information availability that are typical of such spaceflight systems as the Space Shuttle and planetary spacecraft
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