A Non-Demolition Single Spin Meter

We present the theory of a single spin meter consisting of a quantum dot in a magnetic field under microwave irradiation combined with a charge counter. We show that when a current is passed through the dot, a change in the average occupation number occurs if the microwaves are resonant with the on-dot Zeeman splitting. The width of the resonant change is given by the microwave induced Rabi frequency, making the quantum dot a sensitive probe of the local magnetic field and enabling the detection of the state of a nearby spin. If the dot-spin and the nearby spin have different g-factors a non-demolition readout of the spin state can be achieved. The conditions for a reliable spin readout are found.Comment: 4 pages, 5 figure

The Four-Jet Rate in e+e- Annihilation

We present an analytic expression for the four-jet rate in e+e- annihilation, calculated using the coherent branching formalism in the Durham scheme. Our result resums all the leading and next-to-leading kinematic logarithms to all orders in the QCD strong coupling constant.Comment: 7 pages; Final result for R4 and D7 corrected and a couple of typos fixe

Alcohol and drugs in rape and sexual assault

The links between alcohol and sexual assault are now well established and have bee documented in both United Kingdom (UK) and international research (Abbey et al, 2001; Horvath & Brown, 2006a, 2007; Kelly, Lovett & Regan, 2005; Ullman, Karabastsos & Koss, 1999; Walby & Allen, 2004). Although research has identified that administration of alcohol and drugs as means of obtaining illicit sex is not a new phenomenon, it has been argued that the techniques for using alcohol and drugs to facilitate rape have changed and this issue is therefore worthy of renewed interest (Foote, Wangmann & Braff, 2004). This chapter brings together and compares findings from two large independent studies which collected data on the involvement of alcohol and drugs in cases of rape and sexual assault reported to the police and/or sexual assault referral centres. We seek to explore the complexities of alcohol-related sexual assault by outlining a common methodological approach which generates findings that take greater account of the role of the perpetrator, the broader assault context (e.g. the location and relationship between the parties) and other situational characteristics, (e.g. the type of intoxicants consumed and the nature of consumption). The aims of our chapter are to: • promote a broader and more nuanced understanding of the realities of alcohol-related rape, which, we argue, are commonly over-simplified in both academic and popular representations of this crime; • advance the view, based on research evidence, that alcohol is the drug most commonly associated with rape; • and to move beyond the tendency to focus solely on the role and characteristics of victims of alcohol-related sexual assault and incorporate perpetrator characteristics. Our purpose is to dispel some persistent myths about alcohol and drugs in rape in relation to types of substances consumed and the nature of consumption, context, victims and perpetrators. We will present findings from two datasets side by side which is not commonly done and will allow for direct comparison and the generation of new hypotheses

Spin detection at elevated temperatures using a driven double quantum dot

We consider a double quantum dot in the Pauli blockade regime interacting with a nearby single spin. We show that under microwave irradiation the average electron occupations of the dots exhibit resonances that are sensitive to the state of the nearby spin. The system thus acts as a spin meter for the nearby spin. We investigate the conditions for a non-demolition read-out of the spin and find that the meter works at temperatures comparable to the dot charging energy and sensitivity is mainly limited by the intradot spin relaxation.Comment: 8 pages, 6 figure

Scans-Identified Employment Skills and Hampton Roads Employers

There were three goals of this research study: 1) Examine the basic employment skills required by employers; 2) Examine the basic employment skills identified in the SCANS report; 3) Examine the correlation between employer identified skills and the skills outlined in the SCANS report

Global nonlinear optimization of spacecraft protective structures design

The global optimization of protective structural designs for spacecraft subject to hypervelocity meteoroid and space debris impacts is presented. This nonlinear problem is first formulated for weight minimization of the space station core module configuration using the Nysmith impact predictor. Next, the equivalence and uniqueness of local and global optima is shown using properties of convexity. This analysis results in a new feasibility condition for this problem. The solution existence is then shown, followed by a comparison of optimization techniques. Finally, a sensitivity analysis is presented to determine the effects of variations in the systemic parameters on optimal design. The results show that global optimization of this problem is unique and may be achieved by a number of methods, provided the feasibility condition is satisfied. Furthermore, module structural design thicknesses and weight increase with increasing projectile velocity and diameter and decrease with increasing separation between bumper and wall for the Nysmith predictor

Predicting tree distributions in an East African biodiversity hotspot : model selection, data bias and envelope uncertainty

The Eastern Arc Mountains (EAMs) of Tanzania and Kenya support some of the most ancient tropical rainforest on Earth. The forests are a global priority for biodiversity conservation and provide vital resources to the Tanzanian population. Here, we make a first attempt to predict the spatial distribution of 40 EAM tree species, using generalised additive models, plot data and environmental predictor maps at sub 1 km resolution. The results of three modelling experiments are presented, investigating predictions obtained by (1) two different procedures for the stepwise selection of predictors, (2) down-weighting absence data, and (3) incorporating an autocovariate term to describe fine-scale spatial aggregation. In response to recent concerns regarding the extrapolation of model predictions beyond the restricted environmental range of training data, we also demonstrate a novel graphical tool for quantifying envelope uncertainty in restricted range niche-based models (envelope uncertainty maps). We find that even for species with very few documented occurrences useful estimates of distribution can be achieved. Initiating selection with a null model is found to be useful for explanatory purposes, while beginning with a full predictor set can over-fit the data. We show that a simple multimodel average of these two best-model predictions yields a superior compromise between generality and precision (parsimony). Down-weighting absences shifts the balance of errors in favour of higher sensitivity, reducing the number of serious mistakes (i.e., falsely predicted absences); however, response functions are more complex, exacerbating uncertainty in larger models. Spatial autocovariates help describe fine-scale patterns of occurrence and significantly improve explained deviance, though if important environmental constraints are omitted then model stability and explanatory power can be compromised. We conclude that the best modelling practice is contingent both on the intentions of the analyst (explanation or prediction) and on the quality of distribution data; generalised additive models have potential to provide valuable information for conservation in the EAMs, but methods must be carefully considered, particularly if occurrence data are scarce. Full results and details of all species models are supplied in an online Appendix. (C) 2008 Elsevier B.V. All rights reserved

Ensemble based quantum metrology

The field of quantum metrology promises measurement devices that are fundamentally superior to conventional technologies. Specifically, when quantum entanglement is harnessed the precision achieved is supposed to scale more favourably with the resources employed, such as system size and the time required. Here we consider measurement of magnetic field strength using an ensemble of spins, and we identify a third essential resource: the initial system polarisation, i.e. the low entropy of the original state. We find that performance depends crucially on the form of decoherence present; for a plausible dephasing model, we describe a quantum strategy which can indeed beat the standard quantum limit