Resonant Subband Landau Level Coupling in Symmetric Quantum Well

Subband structure and depolarization shifts in an ultra-high mobility GaAs/Al_{0.24}Ga_{0.76}As quantum well are studied using magneto-infrared spectroscopy via resonant subband Landau level coupling. Resonant couplings between the 1st and up to the 4th subbands are identified by well-separated anti-level-crossing split resonance, while the hy-lying subbands were identified by the cyclotron resonance linewidth broadening in the literature. In addition, a forbidden intersubband transition (1st to 3rd) has been observed. With the precise determination of the subband structure, we find that the depolarization shift can be well described by the semiclassical slab plasma model, and the possible origins for the forbidden transition are discussed.Comment: 4 pages, 2 figure

An ontology-based modelling system (OBMS) for representing behaviour change theories applied to 76 theories [version 1; peer review: awaiting peer review]

BACKGROUND: To efficiently search, compare, test and integrate behaviour change theories, they need to be specified in a way that is clear, consistent and computable. An ontology-based modelling system (OBMS) has previously been shown to be able to represent five commonly used theories in this way. We aimed to assess whether the OBMS could be applied more widely and to create a database of behaviour change theories, their constructs and propositions. METHODS: We labelled the constructs within 71 theories and used the OBMS to represent the relationships between the constructs. Diagrams of each theory were sent to authors or experts for feedback and amendment. The 71 finalised diagrams plus the five previously generated diagrams were used to create a searchable database of 76 theories in the form of construct-relationship-construct triples. We conducted a set of illustrative analyses to characterise theories in the database. RESULTS: All 71 theories could be satisfactorily represented using this system. In total, 35 (49%) were finalised with no or very minor amendment. The remaining 36 (51%) were finalised after changes to the constructs (seven theories), relationships between constructs (15 theories) or both (14 theories) following author/expert feedback. The mean number of constructs per theory was 20 (min. = 6, max. = 72), with the mean number of triples per theory 31 (min. = 7, max. = 89). Fourteen distinct relationship types were used, of which the most commonly used was ‘influences’, followed by ‘part of’. CONCLUSIONS: The OBMS can represent a wide array of behavioural theories in a precise, computable format. This system should provide a basis for better integration and synthesis of theories than has hitherto been possible

A survey of UK medical schools' arrangements for early patient contact

Background: Many U.K. medical schools have patient contact in the first two years of the undergraduate course. Aim: To compare the purposes and organization of early patient contact in UK medical schools and to relate these arrangements to the schools' curricular objectives. Methods: A telephone survey of lead educators in UK medicals schools. Categories of contact were plotted against phases of the course to discern patterns of organisation. Results: The quantity of contact varies considerably (four to 65 days). There is a pattern, with learning objectives around the social context of health and illness preceding skills based work and integrated clinical knowledge for practice coming later. Schools fall into three categories: close adherence to the preclinical/clinical split, with limited early contact acting as an introduction to social aspects of health; provision of substantial patient contact to maximize the integration of knowledge and skills; and transitional, with limited clinical goals. General practice provides between one third and one half of early patient contact. Conclusions: Arrangements meet the objectives set by each school and reflect differing educational philosophies. Change is toward more early contact. There appears to be no national guidance which supports a minimum quantity of patient contact or specific educational purpose in the early years of U.K. basic medical training

Upregulation of the cell-cycle regulator RGC-32 in Epstein-Barr virus-immortalized cells

Epstein-Barr virus (EBV) is implicated in the pathogenesis of multiple human tumours of lymphoid and epithelial origin. The virus infects and immortalizes B cells establishing a persistent latent infection characterized by varying patterns of EBV latent gene expression (latency 0, I, II and III). The CDK1 activator, Response Gene to Complement-32 (RGC-32, C13ORF15), is overexpressed in colon, breast and ovarian cancer tissues and we have detected selective high-level RGC-32 protein expression in EBV-immortalized latency III cells. Significantly, we show that overexpression of RGC-32 in B cells is sufficient to disrupt G2 cell-cycle arrest consistent with activation of CDK1, implicating RGC-32 in the EBV transformation process. Surprisingly, RGC-32 mRNA is expressed at high levels in latency I Burkitt's lymphoma (BL) cells and in some EBV-negative BL cell-lines, although RGC-32 protein expression is not detectable. We show that RGC-32 mRNA expression is elevated in latency I cells due to transcriptional activation by high levels of the differentially expressed RUNX1c transcription factor. We found that proteosomal degradation or blocked cytoplasmic export of the RGC-32 message were not responsible for the lack of RGC-32 protein expression in latency I cells. Significantly, analysis of the ribosomal association of the RGC-32 mRNA in latency I and latency III cells revealed that RGC-32 transcripts were associated with multiple ribosomes in both cell-types implicating post-initiation translational repression mechanisms in the block to RGC-32 protein production in latency I cells. In summary, our results are the first to demonstrate RGC-32 protein upregulation in cells transformed by a human tumour virus and to identify post-initiation translational mechanisms as an expression control point for this key cell-cycle regulator

Reduced genomic tumor heterogeneity after neoadjuvat chemotherapy is related to favorable outcome in patients with esophageal adenocarcinoma

Neoadjuvant chemo(radio)therapy followed by surgery is the standard of care for patients with locally advanced resectable esophageal adenocarcinoma (EAC). There is increasing evidence that drug resistance might be related to genomic heterogeneity. We investigated whether genomic tumor heterogeneity is different after cytotoxic chemotherapy and is associated with EAC patient survival. We used arrayCGH and a quantitative assessment of the whole genome DNA copy number aberration patterns (‘DNA copy number entropy’) to establish the level of genomic tumor heterogeneity in 80 EAC treated with neoadjuvant chemotherapy followed by surgery (CS group) or surgery alone (S group). The association between DNA copy number entropy, clinicopathological variables and survival was investigated. DNA copy number entropy was reduced after chemotherapy, even if there was no morphological evidence of response to therapy (p<0.001). Low DNA copy number entropy was associated with improved survival in the CS group (p=0.011) but not in the S group (p=0.396). Our results suggest that cytotoxic chemotherapy reduces DNA copy number entropy, which might be a more sensitive tumor response marker than changes in the morphological tumor phenotype. The use of DNA copy number entropy in clinical practice will require validation of our results in a prospective study

Lipid-soluble Vitamins A, D, and E in HIV-Infected Pregnant women in Tanzania.

There is limited published research examining lipid-soluble vitamins in human immunodeficiency virus (HIV)-infected pregnant women, particularly in resource-limited settings. This is an observational analysis of 1078 HIV-infected pregnant women enrolled in a trial of vitamin supplementation in Tanzania. Baseline data on sociodemographic and anthropometric characteristics, clinical signs and symptoms, and laboratory parameters were used to identify correlates of low plasma vitamin A (<0.7 micromol/l), vitamin D (<80 nmol/l) and vitamin E (<9.7 micromol/l) status. Binomial regression was used to estimate risk ratios and 95% confidence intervals. Approximately 35, 39 and 51% of the women had low levels of vitamins A, D and E, respectively. Severe anemia (hemoglobin <85 g/l; P<0.01), plasma vitamin E (P=0.02), selenium (P=0.01) and vitamin D (P=0.02) concentrations were significant correlates of low vitamin A status in multivariate models. Erythrocyte Sedimentation Rate (ESR) was independently related to low vitamin A status in a nonlinear manner (P=0.01). The correlates of low vitamin D status were CD8 cell count (P=0.01), high ESR (ESR >81 mm/h; P<0.01), gestational age at enrollment (nonlinear; P=0.03) and plasma vitamins A (P=0.02) and E (P=0.01). For low vitamin E status, the correlates were money spent on food per household per day (P<0.01), plasma vitamin A concentration (nonlinear; P<0.01) and a gestational age <16 weeks at enrollment (P<0.01). Low concentrations of lipid-soluble vitamins are widely prevalent among HIV-infected women in Tanzania and are correlated with other nutritional insufficiencies. Identifying HIV-infected persons at greater risk of poor nutritional status and infections may help inform design and implementation of appropriate interventions

Poor Thermal Care Practices among Home Births in Nepal: Further Analysis of Nepal Demographic and Health Survey 2011

Introduction - Hypothermia is a major factor associated with neonatal mortality in low and middle income countries. Thermal care protection of newborn through a series of measures taken at birth and during the initial days of life is recommended to reduce the hypothermia and associated neonatal mortality. This study aimed to identify the prevalence of and the factors associated with receiving ‘optimum thermal care’ among home born newborns of Nepal. Methods - Data from the Nepal Demographic and Health Surveys (NDHS) 2011 were used for this study. Women who reported a home birth for their most recent childbirth was included in the study. Factors associated with optimum thermal care were examined using Chi-square test followed by logistic regression. Results - A total of 2464 newborns were included in the study. A total of 57.6 % were dried before the placenta was delivered; 60.3% were wrapped; 24.5% had not bathing during the first 24 hours, and 63.9% were breastfed within one hour of birth. Overall, only 248 (10.7%; 95% CI (8.8 %, 12.9%)) newborns received optimum thermal care. Newborns whose mothers had achieved higher education (OR 2.810; 95% CI (1.132, 6.976)), attended four or more antenatal care visits (OR 2.563; 95% CI (1.309, 5.017)), and those whose birth were attended by skilled attendants (OR 2.178; 95% CI (1.428, 3.323)) were likely to receive optimum thermal care. Conclusion - The current study showed that only one in ten newborns in Nepal received optimum thermal care. Future newborn survival programs should focus on those mothers who are uneducated; who do not attend the recommended four or more attend antenatal care visits; and those who deliver without the assistance of skilled birth attendants to reduce the risk of neonatal hypothermia in Nepal

Do cravings predict smoking cessation in smokers calling a national quit line: secondary analyses from a randomised trial for the utility of ‘urges to smoke’ measures

BACKGROUND: Single-item urges to smoke measures have been contemplated as important measures of nicotine dependence This study aimed to prospectively determine the relationships between measures of craving to smoke and smoking cessation, and compare their ability to predict cessation with the Heaviness of Smoking Index, an established measure of nicotine dependence. METHODS: We conducted a secondary analysis of data from the randomised controlled PORTSSS trial. Measures of nicotine dependence, ascertained before making a quit attempt, were the HSI, frequency of urges to smoke (FUTS) and strength of urges to smoke (SUTS). Self-reported abstinence at six months after quitting was the primary outcome measure. Multivariate logistic regression and Receiver Operating Characteristic (ROC) analysis were used to assess associations and abilities of the nicotine dependence measures to predict smoking cessation. RESULTS: Of 2,535 participants, 53.5% were female; the median (Interquartile range) age was 38 (28–50) years. Both FUTS and HSI were inversely associated with abstinence six months after quitting; for each point increase in HSI score, participants were 16% less likely to have stopped smoking (OR 0.84, 95% C.I 0.78-0.89, p < 0.0001). Compared to participants with the lowest possible FUTS scores, those with greater scores had generally lower odds of cessation (p across frequency of urges categories=0.0026). SUTS was not associated with smoking cessation. ROC analysis suggested the HSI and FUTS had similar predictive validity for cessation. CONCLUSIONS: Higher FUTS and HSI scores were inversely associated with successful smoking cessation six months after quit attempts began and both had similar validity for predicting cessation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13011-015-0011-8) contains supplementary material, which is available to authorized users

Computer-aided assessment of diagnostic images for epidemiological research

<p>Abstract</p> <p>Background</p> <p>Diagnostic images are often assessed for clinical outcomes using subjective methods, which are limited by the skill of the reviewer. Computer-aided diagnosis (CAD) algorithms that assist reviewers in their decisions concerning outcomes have been developed to increase sensitivity and specificity in the clinical setting. However, these systems have not been well utilized in research settings to improve the measurement of clinical endpoints. Reductions in bias through their use could have important implications for etiologic research.</p> <p>Methods</p> <p>Using the example of cortical cataract detection, we developed an algorithm for assisting a reviewer in evaluating digital images for the presence and severity of lesions. Available image processing and statistical methods that were easily implementable were used as the basis for the CAD algorithm. The performance of the system was compared to the subjective assessment of five reviewers using 60 simulated images. Cortical cataract severity scores from 0 to 16 were assigned to the images by the reviewers and the CAD system, with each image assessed twice to obtain a measure of variability. Image characteristics that affected reviewer bias were also assessed by systematically varying the appearance of the simulated images.</p> <p>Results</p> <p>The algorithm yielded severity scores with smaller bias on images where cataract severity was mild to moderate (approximately ≤ 6/16^<it>ths</it>). On high severity images, the bias of the CAD system exceeded that of the reviewers. The variability of the CAD system was zero on repeated images but ranged from 0.48 to 1.22 for the reviewers. The direction and magnitude of the bias exhibited by the reviewers was a function of the number of cataract opacities, the shape and the contrast of the lesions in the simulated images.</p> <p>Conclusion</p> <p>CAD systems are feasible to implement with available software and can be valuable when medical images contain exposure or outcome information for etiologic research. Our results indicate that such systems have the potential to decrease bias and discriminate very small changes in disease severity. Simulated images are a tool that can be used to assess performance of a CAD system when a gold standard is not available.</p

Co-evolution of density and topology in a simple model of city formation

We study the influence that population density and the road network have on each others' growth and evolution. We use a simple model of formation and evolution of city roads which reproduces the most important empirical features of street networks in cities. Within this framework, we explicitely introduce the topology of the road network and analyze how it evolves and interact with the evolution of population density. We show that accessibility issues -pushing individuals to get closer to high centrality nodes- lead to high density regions and the appearance of densely populated centers. In particular, this model reproduces the empirical fact that the density profile decreases exponentially from a core district. In this simplified model, the size of the core district depends on the relative importance of transportation and rent costs.Comment: 13 pages, 13 figure