Novel metallic and insulating states at a bent quantum Hall junction

A non-planar geometry for the quantum Hall (QH) effect is studied, whereby two quantum Hall (QH) systems are joined at a sharp right angle. When both facets are at equal filling factor nu the junction hosts a channel with non-quantized conductance, dependent on nu. The state is metallic at nu = 1/3, with conductance along the junction increasing as the temperature T drops. At nu = 1, 2 it is strongly insulating, and at nu = 3, 4 shows only weak T dependence. Upon applying a dc voltage bias along the junction, the differential conductance again shows three different behaviors. Hartree calculations of the dispersion at the junction illustrate possible explanations, and differences from planar QH structures are highlighted.Comment: 5 pages, 4 figures, text + figs revised for clarit

Family functioning guidelines for the care of people with spina bifida

Research supports a resilience-disruption model of family functioning in families with a child with spina bifida. Guidelines are warranted to both minimize disruption to the family system and maximize family resilience and adaptation to multiple spina bifida-related and normative stressors. This article discusses the spina bifida family functioning guidelines from the 2018 Spina Bifida Association’s Fourth Edition of the Guidelines for the Care of People with Spina Bifida, and reviews evidence-based directions with the intention of helping individuals with spina bifida achieve optimal mental health throughout their lifespan. Guidelines address clinical questions pertaining to the impact of having a child with spina bifida on family functioning, resilience and vulnerability factors, parenting behaviors that may facilitate adaptive child outcomes, and appropriate interventions or approaches to promote family functioning. Gaps in the research and future directions are discussed

Spots of Adult Male Red-Spotted Newts are Redder and Brighter than in Females: Evidence for a Role in Mate Selection?

As aquatic adults, eastern red-spotted newts (Notophthalmus v. viridescens) are generally green with two rows of dorsal spots, which vary in number between individuals and range in colour from orange to red. The function of these spots is unknown, but it is possible that they serve as sexual ornamentations and we examined this hypothesis by testing for sexual dimorphism in spot characteristics. We used an image analysis approach that has been used previously with this and other amphibian species to compare the number, size and colour – redness (hue score) and brightness – of spots in 100 male and 100 female aquatic adult newts captured during the breeding season in Virginia. While we found no apparent sex-related differences in the numbers of spots, and only a minor difference in spot sizes, we discovered that adult male red-spotted newts had significantly redder and more brightly coloured dorsal spots than did females. We also found that spot brightness is positively associated with body size. As male red-spotted newts entice females to mate in part with a highly visual display (the “hula dance”), the sexual dimorphism in spot colour we found could be associated with this display. Our results, taken together with current knowledge on the carotenoid pigments behind the red spot colour, suggest a role for spot coloration in the mating system of N. v. viridescens that should be examined further and considered in other studies of mate choice. In a more general sense, this discovery also leads us to question if this phenomenon is present in other amphibian species previously thought to be “monomorphic”

Improving Natural History Research with Image Analysis: The Relationship Between Skin Color, Sex, Size and Stage in Adult Red-Spotted Newts

Natural history researchers are increasingly using digital cameras and computer software to measure their study animals. Adult Red-spotted Newts (Notophthalmus viridescens viridescens) are known to display a range of skin colors, from brown to green, but it has not been possible to quantify this variation until the advent of image analysis technology. We used an image analysis approach to compare skin color between sexes, across a range of sizes, and between aquatic and post-breeding (emigrating to the terrestrial habitat) stage adult newts. From 232 individuals (53% male, 47% female) we documented a wide but subtle range of skin colors, measured as the average hue value of all pixels in digital images of each newt body. We found that terrestrial post-breeding individuals were browner than aquatic individuals, consistent with the morphological adaptations of emigrating individuals for the terrestrial habitat. However, we also discovered that males were statistically greener than females but this effect depended on their stage. We suggest this difference may represent different degrees of adaptation for the terrestrial habitat between the sexes. Finally, we used image analysis to obtain measures of body length comparable to traditional snout-vent length and a measure of total body surface area, which provided a better correlation with newt mass than did body length and therefore could potentially serve as an alternative to mass or body condition. We suggest that image analysis methodology offers great promise for future questions relating to size and color in amphibians and provides researchers with an improved way to study aspects of the natural history of amphibians

Real rank boundaries and loci of forms

In this article we study forbidden loci and typical ranks of forms with respect to the embeddings of $\mathbb P^1\times \mathbb P^1$ given by the line bundles $(2,2d)$. We introduce the Ranestad-Schreyer locus corresponding to supports of non-reduced apolar schemes. We show that, in those cases, this is contained in the forbidden locus. Furthermore, for these embeddings, we give a component of the real rank boundary, the hypersurface dividing the minimal typical rank from higher ones. These results generalize to a class of embeddings of $\mathbb P^n\times \mathbb P^1$. Finally, in connection with real rank boundaries, we give a new interpretation of the $2\times n \times n$ hyperdeterminant.Comment: 17 p

Chest X-Ray interpretation: agreement between consultant radiologists and a reporting radiographer in clinical practice in the United Kingdom

Rationale: Driven by developing technology and an ageing population, radiology has witnessed an unprecedented rise in workload. One response to this in the United Kingdom has been to train radiographers to undertake clinical reporting. Accurate interpretation of imaging is crucial to allow clinicians' to correctly manage and treat patients. Methods: A random sample of cases (n=100) was selected from a consecutive series of 1,000 chest x-ray reports produced by a radiographer in clinical practice using a simple computer generated algorithm. Due to the high level of observer variation which is apparent when interpreting chest x-rays, three consultant radiologists were also included to establish the rate of inter-observer variation between radiologists, which was then used as the baseline. Fifty images were interpreted by each radiologist who examined the radiographer report for accuracy and agreement, with 50% duplication of cases between radiologists to determine inter-radiologist variation. The radiologists performed their evaluation independently and blinded to the proportion of cases receiving multiple radiologist opinions. Inter-observer agreement analysis using Kappa was performed to determine consistency among observers. Results: Disagreement was found between the radiologist and radiographer in 7 cases, which in three instances showed agreement between one radiologist and the radiographer. Inter-observer agreement (Kappa statistic) between the three radiologists and the reporting radiographer was found to be almost perfect, K=0.91, 95% confidence interval (0.79,1.0), K=0.91 (0.78,1.0) and K=0.83 (0.68,0.99) respectively. Inter-radiologist agreement was also almost perfect, K=0.82 (0.57,1.0) and K=0.91 (0.75,1.0). Conclusion: The level of inter-observer agreement between radiologist and reporting radiographer chest x-ray interpretation compares favourably with inter-radiologist variation

Quantum Hall Effect in a Two-Dimensional Electron System Bent by 90 Degrees

Using a new MBE growth technique, we fabricate a two-dimensional electron system which is bent around an atomically sharp 90 degree corner. In the quantum Hall regime under tilted magnetic fields, we can measure equilibration between both co- and counter-propagating edge channels of arbitrary filling factor ratio. We present here 4-point magnetotransport characterization of the corner junction with filling factor combinations which can all be explained using the standard Landauer-Buttiker edge channel picture. The success of this description confirms the realization of a new type of quantum Hall edge geometry.Comment: 4 pages, figures included Typographical errors corrected, reference adde

The effect of genome length on ejection forces in bacteriophage lambda

A variety of viruses tightly pack their genetic material into protein capsids that are barely large enough to enclose the genome. In particular, in bacteriophages, forces as high as 60 pN are encountered during packaging and ejection, produced by DNA bending elasticity and self-interactions. The high forces are believed to be important for the ejection process, though the extent of their involvement is not yet clear. As a result, there is a need for quantitative models and experiments that reveal the nature of the forces relevant to DNA ejection. Here we report measurements of the ejection forces for two different mutants of bacteriophage lambda, lambda b221cI26 and lambda cI60, which differ in genome length by ~30%. As expected for a force-driven ejection mechanism, the osmotic pressure at which DNA release is completely inhibited varies with the genome length: we find inhibition pressures of 15 atm and 25 atm, respectively, values that are in agreement with our theoretical calculations