Detecting Technibaryon Dark Matter

The technibaryon constitutes a possible dark matter candidate. Such a particle with electroweak quantum numbers is already nearly ruled out as the dominant component of the galactic dark matter by nuclear recoil experiments. Here, the scattering of singlet technibaryons, without electroweak quantum numbers, is considered. For scalar technibaryons the most important interaction is the charge radius. The scattering rates are typically of order $10^{-4}$ (kg keV day)$^{-1}$ for a technicolor scale of 1 TeV. For fermionic technibaryons the most important interaction is the magnetic dipole moment. The scattering rates in this case are considerably larger, typically between $10^{-1}$ and 1 (kg keV day)$^{-1}$, depending on the detector material. Rates this large may be detectable in the next generation of nuclear recoil experiments. Such experiments will also be sensitive to quite small technibaryon electric dipole moments.Comment: 11 pages, Tex file, requires phyzzx, Santa Cruz preprint SCIPP 93/3

Introduction to papers on astrostatistics

We are pleased to present a Special Section on Statistics and Astronomy in this issue of the The Annals of Applied Statistics. Astronomy is an observational rather than experimental science; as a result, astronomical data sets both small and large present particularly challenging problems to analysts who must make the best of whatever the sky offers their instruments. The resulting statistical problems have enormous diversity. In one problem, one may have to carefully quantify uncertainty in a hard-won, sparse data set; in another, the sheer volume of data may forbid a formally optimal analysis, requiring judicious balancing of model sophistication, approximations, and clever algorithms. Often the data bear a complex relationship to the underlying phenomenon producing them, much in the manner of inverse problems.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS234 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Design of a Recreational Fishing Survey and Mark-Recapture Study for the Blue Crab, Callinectes sapidus, in Chesapeake Bay

The development of bay wide estimates of recreational harvest has been identified as a high priority by the Chesapeake Bay Scientific Advisory Committee (CBSAC) and by the Chesapeake Bay Program as reflected in the Chesapeake Bay Blue Crab Fishery Management Plan (Chesapeake Bay Program 1996). In addition, the BiState Blue Crab Commission (BBCAC), formed in 1996 by mandate from the legislatures of Maryland and Virginia to advise on crab management, has also recognized the importance of estimating the levels and trends in catches in the recreational fishery. Recently, the BBCAC has adopted limit and target biological reference points. These analyses have been predicated on assumptions regarding the relative magnitude of the recreational and commercial catch. The reference points depend on determination of the total number of crabs removed from the population. In essence, the number removed by the various fishery sectors, represents a minimum estimate of the population size. If a major fishery sector is not represented, the total population will be accordingly underestimated. If the relative contribution of the unrepresented sector is constant over time and harvests the same components of the population as the other sectors, it may be argued that the population estimate derived from the other sectors is biased but still adequately represents trends in population size over time. If either of the two constraints mentioned above is not met, the validity of relative trends over time is suspect. With the recent increases in the human population in the Chesapeake Bay watershed, there is reason to be concerned that the recreational catch may not have been a constant proportion of the total harvest over time. It is important to assess the catch characteristics and the magnitude of the recreational fishery to evaluate this potential bias. (PDF contains 70 pages

Weak (anti)localization in tubular semiconductor nanowires with spin-orbit coupling

We compute analytically the weak (anti)localization correction to the Drude conductivity for electrons in tubular semiconductor systems of zinc blende type. We include linear Rashba and Dresselhaus spin-orbit coupling (SOC) and compare wires of standard growth directions $\langle100\rangle$, $\langle111\rangle$, and $\langle110\rangle$. The motion on the quasi-two-dimensional surface is considered diffusive in both directions: transversal as well as along the cylinder axis. It is shown that Dresselhaus and Rashba SOC similarly affect the spin relaxation rates. For the $\langle110\rangle$ growth direction, the long-lived spin states are of helical nature. We detect a crossover from weak localization to weak anti-localization depending on spin-orbit coupling strength as well as dephasing and scattering rate. The theory is fitted to experimental data of an undoped $\langle111\rangle$ InAs nanowire device which exhibits a top-gate-controlled crossover from positive to negative magnetoconductivity. Thereby, we extract transport parameters where we quantify the distinct types of SOC individually.Comment: 17 pages, 9 figure

Workplace-based assessment in clinical radiology in the UK - a validity study

In 2010, the Royal College of Radiologists introduced workplace-based assessments to the postgraduate training pathway for clinical radiologists in the UK. Whilst the system served the purpose of contributing to high-stakes annual judgements about radiology trainees’ progression into subsequent years of training, it was primarily intended to be formative. This study was prompted by an interest in whether the new system fulfilled this formative role. Data collection and analysis spanned the first three years of the new system and followed a multi-methods approach. Descriptive statistical analysis was used to explore important parameters such as the timing and number of assessments undertaken by trainees and assessors. Using the literature and an iterative analysis of a large sample of trainee data, a coding framework for categories of feedback quality enabled assessors’ written comments to be explored using deductive and inductive qualitative analysis, with inferential statistical analysis of coded assessor feedback statements. For example, Ragin’s (1987, 2000, 2008) qualitative comparative analysis, QCA, was used to explore whether the assessments met necessary and/or sufficient conditions for high quality feedback. Pairs of assessor-trainee feedback comments were also analysed to establish whether any dialogic feedback interactions occurred. The study presents evidence that despite its intentions, the new system is generally failing to meet its primary, formative aim. As a consequence, the influence of negative washback on assessment practice was reflected in a number of findings. For example, there was evidence of trainees taking an instrumental approach to the assessments, undertaking only the prescribed minimum of assessments or completing assessments in the later stages of placements. Combined with evidence of retrospective assessment, i.e. after completion of the placements, the observed patterns of assessment over the three years are consistent with a box-ticking approach. This study explores the contextual policy and practice dimensions underpinning these and related findings and discusses the implications and recommendations for future arrangements

A Guide to Knowing Your Rights with the Police and Getting Out of Jail: Booklet 2

ArchCity Defenders created a self-advocating guide for people to use if they have an encounter with the police, jail or the courts