Gender differences in conceptual understanding of Newtonian mechanics: a UK cross-institution comparison

We present results of a combined study from three UK universities where we investigate the existence and persistence of a performance gender gap in conceptual understanding of Newtonian mechanics. Using the Force Concept Inventory, we find that students at all three universities exhibit a statistically significant gender gap, with males outperforming females. This gap is narrowed but not eliminated after instruction, using a variety of instructional approaches. Furthermore, we find that before instruction the quartile with the lowest performance on the diagnostic instrument comprises a disproportionately high fraction (~50%) of the total female cohort. The majority of these students remain in the lowest-performing quartile post-instruction. Analysis of responses to individual items shows that male students outperform female students on practically all items on the instrument. Comparing the performance of the same group of students on end-of-course examinations, we find no statistically significant gender gaps.Comment: 17 page

UK Renal Registry 18th Annual Report: Chapter 3 Demographic and Biochemistry Profile of Kidney Transplant Recipients in the UK in 2014: National and Centre-specific Analyses.

There was a 2% fall in overall renal transplant numbers in 2014, with a significant fall in kidney donation from donors after circulatory death (10%). In 2014, death-censored renal transplant failure rates in prevalent patients were similar to previous years at 2.4% per annum. Transplant patient death rates remained stable at 2.3 per 100 patient years. The median age of incident and prevalent renal transplant patients in the UK was 50.6 and 53.3 years respectively. The median eGFR of prevalent renal transplant recipients was 52.5 ml/min/1.73 m2. The median eGFR of patients one year after transplantation was 57.4 ml/min/1.73 m2 post live transplant, 53.6 ml/min/1.73 m2 post brainstem death transplant and 50.1 ml/min/1.73 m2 post circulatory death transplant. In 2014, 13% of prevalent transplant patients had eGFR ,30 ml/min/1.73 m2. The median decline in eGFR slope beyond the first year after transplantation was −0.48 ml/min/1.73 m2/year.In 2014, malignancy (26%) and infection (24%) remained the commonest causes of death in patients with a functioning renal transplant

Angular asymptotics for multi-dimensional non-homogeneous random walks with asymptotically zero drift

We study the first exit time $\tau$ from an arbitrary cone with apex at the origin by a non-homogeneous random walk (Markov chain) on $\Z^d$ ($d \geq 2$) with mean drift that is asymptotically zero. Specifically, if the mean drift at \bx \in \Z^d is of magnitude O(\| \bx\|^{-1}), we show that $\tau<\infty$ a.s. for any cone. On the other hand, for an appropriate drift field with mean drifts of magnitude \| \bx\|^{-\beta}, $\beta \in (0,1)$, we prove that our random walk has a limiting (random) direction and so eventually remains in an arbitrarily narrow cone. The conditions imposed on the random walk are minimal: we assume only a uniform bound on $2$nd moments for the increments and a form of weak isotropy. We give several illustrative examples, including a random walk in random environment model

International Trade, Foreign Direct Investment, and Domestic Market Performance

We develop a model to estimate simultaneously import shares, export shares, outward foreign direct investment and domestic profits for a large sample of U.S. manufacturing industries. In our model, trade barriers alter the ability of domestic market structure to influence domestic performance. The results indicate that trade flows behave as expected in response to factor intensity. Profits are disciplined by imports and enhanced by exports. Concentration reduces both import and export shares but economies of scale increase them. Exports are complements rather than substitutes for foreign direct investment.Concentration; Exports; Foreign Direct Investment; Import; International Trade; Market Performance; Market Structure; Trade

Body Size in Amblyrhiza inundata (Rodentia, Caviomorpha), an Extinct Megafaunal Rodent From the Anguilla Bank, West Indies: Estimates and Implications

Rodent species typically evolve larger mean body sizes when isolated on islands, but the extinct caviomorph Amblyrhiza inundata, known only from Quaternary cave deposits on the islands of Anguilla and St. Martin (northern Lesser Antilles), provides an unusually dramatic example of insular gigantism. Here we report on a series of body mass estimates for Amblyrhiza using predictive equations based on anteroposterior diameters and cortical cross-sectional areas of humeral and femoral diaphyses. Analyses of 14 isolated specimens (5 femoral, 9 humeral), all representing adult or near adult animals, yield body mass estimates ranging from slightly less than 50 kg to more than 200 kg. Body size estimates derived from humeral measurements are lower than those derived from femoral measurements, but the significance of this will remain unclear until matched limb bones (i.e., specimens from the same animal) are recovered. Incisor measurements are also highly variable, but in this case the distribution is demonstrably bimodal. Presence of multiple coeval species, temporal variation, limb heterogeneity, and sexual dimorphism all qualify as possible explanations of the variation encountered in Amblyrhiza data sets, but available samples are not adequate for making a robust choice among them. Body size affects many life history variables, including demography. Population estimates derived from empirical data and predictive equations suggest that only a few thousand individuals of Amblyrhiza could have occupied the islands of the Anguilla Bank at any one time during the Late Quaternary. At certain times-for example, during the last interglacial (Sangamonian) highstand-population numbers might have sunk to only a few hundred. Absolutely small population sizes of Amblyrhiza and severe fluctuations in island area during the late Quaternary surely affected its susceptibility to extinction, whether or not humans were ultimately responsible for the event (for which there is as yet no direct evidence)

Notoungulate caudal cranium.

69 pages : illustrations ; 26 cmThe composition of the caudal cranium in Notoungulata, an extinct group of endemic South American "ungulates," has never been properly clarified. Some investigators have claimed that so-called "adventitious" elements, or elements not known to occur in other placentals, existed in the auditory regions of certain typotheres and toxodontians. Others have disputed this, arguing that sutures or other indicia that supposedly provide evidence of the developmentally independent origins of these alleged ossifications are either misinterpreted or inconstant. This study attempts to resolve the question of composition, as far as it is possible to do in the case of a wholly extinct clade, with detailed micro-CT investigations of several key taxa, including Oldfieldthomasia (Oldfieldthomasiidae), Paedotherium (Hegetotheriidae), and Cochilius (Interatheriidae). Results show that Santiago Roth was incorrect in asserting that certain notoungulates, such as pachyrukhine hegetotheres, possessed cranial elements (serrialis, posttympanicum, etc.) that are unrepresented in other placentals. George Gaylord Simpson also thought Roth was wrong, but erred in claiming to have discovered concrete evidence of two other ossifications, denoted by him as Xa and Xp, in the auditory region of Oldfieldthomasia. In adult notoungulates the interparietal complex is usually fused with the parietal, or supraoccipital, or both elements. As in certain other mammals, dorsal exposure of the supraoccipital is limited in notoungulates because it is often overplated by the interparietal complex, which thus provides a sort of "second" roof for the caudal cranium. However, there is no interparietal involvement in the middle ear cavity. Finally, for the first time plausible grounds can be offered for the existence of an entotympanic in a notoungulate (Cochilius). Evidence is increasing for the proposition that entotympanics are much more widespread than previously thought, and may in fact be present in most of the major groups of placentals. In summary, this study shows that in terms of participating elements there is nothing unique about the notoungulate caudal cranium, which was evidently as tightly constrained compositionally as it is in other placentals. Nevertheless, this portion of the skull, still notably underutilized in notoungulate studies, could be a crucial source of new characters for assessing higher-level relationships not only among notoungulates, but also among South American ungulates and their possible relatives