A Mathematical Model for Epitaxial Semiconductor Crystal Growth from the Vapor Phase on a Masked Substrate

Certain materials used in lasers are made by a process called epitaxial semiconductor crystal growth. In this report a mathematical model is developed for this growth process which occurs on a substrate at the junction between a masked region and exposed substrate in a vapor. This new model consists of two partial differential equations; one for the surface dynamics and one for the crystal growth on the exposed substrate. An analysis of the steady state solutions is furnished. Approximate solutions for time-dependent cases are found using two numerical methods. An asymptotic analysis is also carried out to determine transient solution behavior. The undesireable "bump" structure at the mask/substrate junction which has been observed experimentally is present in the solutions found by each method

The shape and dynamics of a heliotropic dusty ringlet in the Cassini Division

The so-called "Charming Ringlet" (R/2006 S3) is a low-optical-depth, dusty ringlet located in the Laplace gap in the Cassini Division. This ringlet is particularly interesting because its radial position varies systematically with longitude relative to the Sun in such a way that the ringlet's geometric center appears to be displaced away from Saturn's center in a direction roughly toward the Sun. In other words, the ringlet is always found at greater distances from the planet's center at longitudes near the sub-solar longitude than it is at longitudes near Saturn's shadow. This "heliotropic" behavior indicates that the dynamics of the particles in this ring are being influenced by solar radiation pressure. In order to investigate this phenomenon, which has been predicted theoretically but has never been observed this clearly, we analyze multiple image sequences of this ringlet obtained by Cassini in order to constrain its shape and orientation. These data can be fit reasonably well with a model in which both the eccentricity and the inclination of the ringlet have "forced" components (that maintain a fixed orientation relative to the Sun) as well as "free" components (that drift around the planet at steady rates determined by Saturn's oblateness). While the magnitude of the forced eccentricity is roughly consistent with theoretical expectations for radiation pressure acting on 10-to-100-micron-wide icy grains, the existence of significant free eccentricities and inclinations poses a significant challenge for models of low-optical-depth dusty rings.Comment: 31 pages, 6 figures, accepted for publication in Icarus. Slight edits made to match various proof correction

The Importance of Time Congruity in the Organisation.

In 1991 Kaufman, Lane, and Lindquist proposed that time congruity in terms of an individual's time preferences and the time use methods of an organisation would lead to satisfactory performance and enhancement of quality of work and general life. The research reported here presents a study which uses commensurate person and job measures of time personality in an organisational setting to assess the effects of time congruity on one aspect of work life, job-related affective well-being. Results show that time personality and time congruity were found to have direct effects on well-being and the influence of time congruity was found to be mediated through time personality, thus contributing to the person–job (P–J) fit literature which suggests that direct effects are often more important than indirect effects. The study also provides some practical examples of ways to address some of the previously cited methodological issues in P–J fit research

Retrospective analysis of alpha‐human papillomavirus (HPV) types in tissue samples from anogenital dysplasias – introduction of the RICH (Risk of HPV‐related Carcinoma in HIV+/− patients) score

Background Chronic viral infections caused by highly contagious human papillomaviruses (HPVs) from the alpha genus are a substantial risk factor for tumour diseases. Objectives The goal of this study was to compare the HPV infection pattern with histology in a patient group of immunocompromised HIV+ and non‐immunocompromised patients with anal intraepithelial neoplasia. Materials and Methods Tissue samples (n = 210) from the anogenital area of 121 patients underwent retrospective histological and molecular examination for HPV DNA prevalence by chip analysis. The study was part of a cancer screening from the Dermatology Department of the LMU Munich, Germany. All data were collected and processed anonymously. Results HPV 6 or 11 are more abundant in tissue samples from histologically diagnosed condylomata acuminata (47.7%) compared to grade 1, 2, and 3 intraepithelial neoplasias (IN 1‐3). Detection of high‐risk (hr) alpha‐HPV DNA was significantly higher in tissue samples from IN 3 (67.5%) compared to IN 1 and 2 (12.9%), and compared to condylomata acuminata (29.5%). No HPV types were detected in histologically unremarkable tissue samples. There was a significant association between the prevalence of HPV 16 and the classifications IN 1 to IN 3 (χ2 (2) = 13.62, P = 0.001). We identified a significant correlation between the prevalence of high‐risk and low‐risk (lr) HPV types and HIV, especially mixed infections of different HPV types correlated with high‐grade IN. Based on the present data, we suggest the risk of carcinoma in HIV+/− patients (RICH) score and test it in the 121 patients. Conclusions hr alpha‐HPVs, mainly HPV 16, are associated with increased oncogenic potential of premalignant lesions (IN 1‐3), especially in HIV+ patients. Based on the combination of HIV/HPV‐testing and histological analysis, we identified correlations that could potentially forecast the risk of malignant transformation and summarized them in the form of RICH score

Repetitive task training for improving functional ability after stroke

<p><b>Objectives:</b> The objective of this review was to determine if repetitive task training after stroke improves global, upper, or lower limb function and if treatment effects are influenced by the amount, type, or timing of practice.</p> <p><b>Search Strategy:</b> We searched the Cochrane Stroke Trials Register (to October 2006); The Cochrane Library, MEDLINE, EMBASE, CINAHL, AMED, SportDiscus, Science Citation Index, Index to Theses, ZETOC, PEDro, and OT Seeker (all to September 2006); and OT search (to March 2006). We also searched for unpublished/non-English language trials; combed conference proceedings and reference lists; requested information on bulletin boards; and contacted trial authors.</p> <p><b>Selection Criteria:</b> Selection criteria included randomized/quasirandomized trials in adults after stroke, of interventions that included an active motor sequence performed repetitively within a single training session, a clear functional goal, and a quantifiable level of practice.</p> <p><b>Data Collection and Analysis:</b> Two authors independently screened abstracts, extracted data, and appraised trial quality. Further information was obtained from study authors. Results from individual trials were combined using meta-analytic techniques appropriate to the data extracted and the level of between-trial heterogeneity.</p> <p><b>Main Results:</b> Fourteen trials with 17 intervention-control pairs and 659 participants were included. Primary outcomes showed that treatment effects were statistically significant for walking distance (see the Figure); walking speed (standardized mean difference, 0.29; 95% CI, 0.04 to 0.53); and sit-to-stand (standardized effect estimate, 0.35; 95% CI, 0.13 to 0.56). Treatment effects were of borderline statistical significance for functional ambulation.</p&gt

Selective disruption of Tcf7l2 in the pancreatic β cell impairs secretory function and lowers β cell mass.

Type 2 diabetes (T2D) is characterized by β cell dysfunction and loss. Single nucleotide polymorphisms in the T-cell factor 7-like 2 (TCF7L2) gene, associated with T2D by genome-wide association studies, lead to impaired β cell function. While deletion of the homologous murine Tcf7l2 gene throughout the developing pancreas leads to impaired glucose tolerance, deletion in the β cell in adult mice reportedly has more modest effects. To inactivate Tcf7l2 highly selectively in β cells from the earliest expression of the Ins1 gene (∼E11.5) we have therefore used a Cre recombinase introduced at the Ins1 locus. Tcfl2(fl/fl)::Ins1Cre mice display impaired oral and intraperitoneal glucose tolerance by 8 and 16 weeks, respectively, and defective responses to the GLP-1 analogue liraglutide at 8 weeks. Tcfl2(fl/fl)::Ins1Cre islets displayed defective glucose- and GLP-1-stimulated insulin secretion and the expression of both the Ins2 (∼20%) and Glp1r (∼40%) genes were significantly reduced. Glucose- and GLP-1-induced intracellular free Ca(2+) increases, and connectivity between individual β cells, were both lowered by Tcf7l2 deletion in islets from mice maintained on a high (60%) fat diet. Finally, analysis by optical projection tomography revealed ∼30% decrease in β cell mass in pancreata from Tcfl2(fl/fl)::Ins1Cre mice. These data demonstrate that Tcf7l2 plays a cell autonomous role in the control of β cell function and mass, serving as an important regulator of gene expression and islet cell coordination. The possible relevance of these findings for the action of TCF7L2 polymorphisms associated with Type 2 diabetes in man is discussed

Schmidt-hammer exposure ages from periglacial patterned ground (sorted circles) in Jotunheimen, Norway, and their interpretative problems

© 2016 Swedish Society for Anthropology and Geography Periglacial patterned ground (sorted circles and polygons) along an altitudinal profile at Juvflya in central Jotunheimen, southern Norway, is investigated using Schmidt-hammer exposure-age dating (SHD). The patterned ground surfaces exhibit R-value distributions with platycurtic modes, broad plateaus, narrow tails, and a negative skew. Sample sites located between 1500 and 1925 m a.s.l. indicate a distinct altitudinal gradient of increasing mean R-values towards higher altitudes interpreted as a chronological function. An established regional SHD calibration curve for Jotunheimen yielded mean boulder exposure ages in the range 6910 ± 510 to 8240 ± 495 years ago. These SHD ages are indicative of the timing of patterned ground formation, representing minimum ages for active boulder upfreezing and maximum ages for the stabilization of boulders in the encircling gutters. Despite uncertainties associated with the calibration curve and the age distribution of the boulders, the early-Holocene age of the patterned ground surfaces, the apparent cessation of major activity during the Holocene Thermal Maximum (HTM) and continuing lack of late-Holocene activity clarify existing understanding of the process dynamics and palaeoclimatic significance of large-scale sorted patterned ground as an indicator of a permafrost environment. The interpretation of SHD ages from patterned ground surfaces remains challenging, however, owing to their diachronous nature, the potential for a complex history of formation, and the influence of local, non-climatic factors

Practicalities of using non-local or non-recent multilocus sequence typing data for source attribution in space and time of human campylobacteriosis

In this study, 1208 Campylobacter jejuni and C. coli isolates from humans and 400 isolates from chicken, collected in two separate periods over 12 years in The Netherlands, were typed using multilocus sequence typing (MLST). Statistical evidence was found for a shift of ST frequencies in human isolates over time. The human MLST data were also compared to published data from other countries to determine geographical variation. Because only MLST typed data from chicken, taken from the same time point and spatial location, were available in addition to the human data, MLST datasets for other Campylobacter reservoirs from selected countries were used. The selection was based on the degree of similarity of the human isolates between countries. The main aim of this study was to better understand the consequences of using non-local or non-recent MLST data for attributing domestically acquired human Campylobacter infections to specific sources of origin when applying the asymmetric island model for source attribution. In addition, a power-analysis was done to find the minimum number of source isolates needed to perform source attribution using an asymmetric island model. This study showed that using source data from other countries can have a significant biasing effect on the attribution results so it is important to carefully select data if the available local data lack in quality and/or quantity. Methods aimed at reducing this bias were proposed

Corresponding morphological and molecular indicators of crude oil toxicity to the developing hearts of mahi mahi

Crude oils from distinct geological sources worldwide are toxic to developing fish hearts. When oil spills occur in fish spawning habitats, natural resource injury assessments often rely on conventional morphometric analyses of heart form and function. The extent to which visible indicators correspond to molecular markers for cardiovascular stress is unknown for pelagic predators from the Gulf of Mexico. Here we exposed mahi (Coryphaena hippurus) embryos to field-collected crude oil samples from the 2010 Deepwater Horizon disaster. We compared visible heart defects (edema, abnormal looping, reduced contractility) to changes in expression of cardiac-specific genes that are diagnostic of heart failure in humans or associated with loss-of-function zebrafish cardiac mutants. Mahi exposed to crude oil during embryogenesis displayed typical symptoms of cardiogenic syndrome as larvae. Contractility, looping, and circulatory defects were evident, but larval mahi did not exhibit downstream craniofacial and body axis abnormalities. A gradation of oil exposures yielded concentration-responsive changes in morphometric and molecular responses, with relative sensitivity being influenced by age. Our findings suggest that 1) morphometric analyses of cardiac function are more sensitive to proximal effects of crude oil-derived chemicals on the developing heart, and 2) molecular indicators reveal a longer-term adverse shift in cardiogenesis trajectory