Asymptotic behaviour of multiple scattering on infinite number of parallel demi-planes

The exact solution for the scattering of electromagnetic waves on an infinite number of parallel demi-planes has been obtained by J.F. Carlson and A.E. Heins in 1947 using the Wiener-Hopf method. We analyze their solution in the semiclassical limit of small wavelength and find the asymptotic behaviour of the reflection and transmission coefficients. The results are compared with the ones obtained within the Kirchhoff approximation

Quantitative Flow Cytometry to Understand Population Heterogeneity in Response to Changes in Substrate Availability in Escherichia coli and Saccharomyces cerevisiae Chemostats

Microbial cells in bioprocesses are usually described with averaged parameters. But in fact, single cells within populations vary greatly in characteristics such as stress resistance, especially in response to carbon source gradients. Our aim was to introduce tools to quantify population heterogeneity in bioprocesses using a combination of reporter strains, flow cytometry, and easily comprehensible parameters. We calculated mean, mode, peak width, and coefficient of variance to describe distribution characteristics and temporal shifts in fluorescence intensity. The skewness and the slope of cumulative distribution function plots illustrated differences in distribution shape. These parameters are person-independent and precise. We demonstrated this by quantifying growth-related population heterogeneity of Saccharomyces cerevisiae and Escherichia coli reporter strains in steady-state of aerobic glucose-limited chemostat cultures at different dilution rates and in response to glucose pulses. Generally, slow-growing cells showed stronger responses to glucose excess than fast-growing cells. Cell robustness, measured as membrane integrity after exposure to freeze-thaw treatment, of fast-growing cells was strongly affected in subpopulations of low membrane robustness. Glucose pulses protected subpopulations of fast-growing but not slower-growing yeast cells against membrane damage. Our parameters could successfully describe population heterogeneity, thereby revealing physiological characteristics that might have been overlooked during traditional averaged analysis

Methicillin-resistant staphylococcus aureus in children attending school in cartagena, colombia

Objective Determining nasal carriers of methicillin-resistant Staphylococcus aureus (MRSA) and associated risk factors for nasal colonisation in a school-aged population in the seaside city of Cartagena, Colombia. Methods A cross-sectional, analytical study was carried out on 100 healthy schoolchildren to determine MRSA nasal carriage and its association with risk factors. Bacteria were identified using conventional methods. Antibiotic sensitivity was determined by the Kirby Bauer method. Results A total of 36 isolates of S. aureus were identified in the school children. 25 % of the strains were oxacillin-resistant, 66.7 % oxacillin-sensitive and 8.3 % had intermediate susceptibility. 67 % of the MRSA strains isolated were sensitive to all antibiotics tested. One strain (MRSA-Ant4) showed resistance to antibiotics having different mechanisms of action. Conclusions This is the first study in Cartagena which determined the frequency of S. aureus and MRSA strains nasal carriers in a school population (33 % and 9 %, respectively). All S. aureus oxacillin-resistant strains were cephoxitin-resistant, thereby leading to the presence of the mecA gene being suspected. Having used beta-lactam antibiotics during the last three months increased the likelihood of being an MRSA nasal carrier by around five times (OR=4.72; 0.96-23.98 95 %CL; pObjetivo Determinar portadores nasales de Staphylococcus aureus resistente a meticilina (SARM) y factores de riesgo asociados a esta colonización, en una población escolar de Cartagena de Indias.  Métodos Se realizó un estudio analítico  transversal en 100 niños escolares sanos, para la búsqueda de portadores nasales de cepas SARM y su asociación con factores de riesgo. Para la identificación bacteriana se utilizaron métodos convencionales. A todos los aislamientos se les determinó la sensibilidad a antibióticos por el método de Kirby-Bauer. Resultados De la población escolar, se identificaron 36 cepas de S. aureus; 25 %, oxacilino-resistentes; 66,7 %, oxacilino-sensibles y 8,3 %, con sensibilidad intermedia. El 67 % de cepas SARM aisladas fueron sensibles a todos los antibióticos probados. Una cepa (SARM-Ant4) presentó resistencia a tres antibióticos con mecanismos de acción diferentes. Conclusiones Este es el primer estudio realizado en Cartagena, que determinó las frecuencias de portadores nasales de S. aureus y cepas SARM en una población escolar, registrándose un 33 % y 9 %, respectivamente. Todas las cepas de S. aureus oxacilino-resistente, fueron también cefoxitino-resistente, lo que hace sospechar la presencia del gen mecA.  El uso de antibióticos betalactámicos en los últimos tres meses, incrementa aproximadamente cinco veces más el riesgo de ser portador nasal de cepas SARM (aOR=4,72 [IC95%=0,96-23,98] 

Between learning and schooling: the politics of human rights monitoring at the Universal Periodic Review

This paper explores the politics of monitoring at the Universal Periodic Review (UPR), a new United Nations human rights monitoring mechanism which aims to promote a universal approach and equal treatment when reviewing each country’s human rights situation. To what extent are these laudable aims realised, and realisable, given entrenched representations of the West and the Rest as well as geopolitical and economic inequalities both historically and in the present? Based on ethnographic fieldwork at the UN in 2010–11, the final year of the UPR’s first cycle, we explore how these aims were both pursued and subverted, paying attention to two distinct ways of talking about the UPR: first, as a learning culture in which UN member states ‘share best practice’ and engage in constructive criticism; and second, as an exam which UN member states face as students with vastly differing attitudes and competences. Accounts and experiences of diplomats from states that are not placed in the ‘good students’ category offer valuable insights into the inherent contradictions of de-historicised and de-contextualised approaches to human rights

On the representation theorems of Poisson, Riemann and Volterra for the Euler-Poisson-Darboux equation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46183/1/205_2004_Article_BF00248204.pd

An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types

Novel lines of Pax6-/- embryonic stem cells exhibit reduced neurogenic capacity without loss of viability

<p>Abstract</p> <p>Background</p> <p>Embryonic stem (ES) cells can differentiate into all cell types and have been used extensively to study factors affecting neuronal differentiation. ES cells containing mutations in known genes have the potential to provide useful in vitro models for the study of gene function during neuronal differentiation. Recently, mouse ES cell lines lacking the neurogenic transcription factor Pax6 were reported; neurons derived from these <it>Pax6</it>^-/-ES cells died rapidly after neuronal differentiation in vitro.</p> <p>Results</p> <p>Here we report the derivation of new lines of <it>Pax6</it>^-/-ES cells and the assessment of their ability to survive and differentiate both in vitro and in vivo. Neurons derived from our new <it>Pax6</it>^-/-lines were viable and continued to elaborate processes in culture under conditions that resulted in the death of neurons derived from previously reported <it>Pax6</it>^-/-ES cell lines. The new lines of <it>Pax6</it>^-/-ES cells showed reduced neurogenic potential, mimicking the effects of loss of Pax6 in vivo. We used our new lines to generate <it>Pax6</it>^-/-↔ <it>Pax6</it>^+/+chimeras in which the mutant cells survived and displayed the same phenotypes as <it>Pax6</it>^-/-cells in <it>Pax6</it>^-/-↔ <it>Pax6</it>^+/+chimeras made by embryo aggregation.</p> <p>Conclusions</p> <p>We suggest that loss of Pax6 from ES cells reduces their neurogenic capacity but does not necessarily result in the death of derived neurons. We offer these new lines as additional tools for those interested in the generation of chimeras and the analysis of in vitro ES cell models of Pax6 function during neuronal differentiation, embryonic and postnatal development.</p

Quantitative Comparison of Constitutive Promoters in Human ES cells

BACKGROUND: Constitutive promoters that ensure sustained and high level gene expression are basic research tools that have a wide range of applications, including studies of human embryology and drug discovery in human embryonic stem cells (hESCs). Numerous cellular/viral promoters that ensure sustained gene expression in various cell types have been identified but systematic comparison of their activities in hESCs is still lacking. METHODOLOGY/PRINCIPAL FINDINGS: We have quantitatively compared promoter activities of five commonly used constitutive promoters, including the human β-actin promoter (ACTB), cytomegalovirus (CMV), elongation factor-1α, (EF1α), phosphoglycerate kinase (PGK) and ubiquitinC (UbC) in hESCs. Lentiviral gene transfer was used to ensure stable integration of promoter-eGFP constructs into the hESCs genome. Promoter activities were quantitatively compared in long term culture of undifferentiated hESCs and in their differentiated progenies. CONCLUSION/SIGNIFICANCE: The ACTB, EF1α and PGK promoters showed stable activities during long term culture of undifferentiated hESCs. The ACTB promoter was superior by maintaining expression in 75-80% of the cells after 50 days in culture. During embryoid body (EB) differentiation, promoter activities of all five promoters decreased. Although the EF1α promoter was downregulated in approximately 50% of the cells, it was the most stable promoter during differentiation. Gene expression analysis of differentiated eGFP+ and eGFP- cells indicate that promoter activities might be restricted to specific cell lineages, suggesting the need to carefully select optimal promoters for constitutive gene expression in differentiated hESCs

Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context

Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts