Self-consistent Green's function method for nuclei and nuclear matter

Recent results obtained by applying the method of self-consistent Green's functions to nuclei and nuclear matter are reviewed. Particular attention is given to the description of experimental data obtained from the (e,e'p) and (e,e'2N) reactions that determine one and two-nucleon removal probabilities in nuclei since the corresponding amplitudes are directly related to the imaginary parts of the single-particle and two-particle propagators. For this reason and the fact that these amplitudes can now be calculated with the inclusion of all the relevant physical processes, it is useful to explore the efficacy of the method of self-consistent Green's functions in describing these experimental data. Results for both finite nuclei and nuclear matter are discussed with particular emphasis on clarifying the role of short-range correlations in determining various experimental quantities. The important role of long-range correlations in determining the structure of low-energy correlations is also documented. For a complete understanding of nuclear phenomena it is therefore essential to include both types of physical correlations. We demonstrate that recent experimental results for these reactions combined with the reported theoretical calculations yield a very clear understanding of the properties of {\em all} protons in the nucleus. We propose that this knowledge of the properties of constituent fermions in a correlated many-body system is a unique feature of nuclear physics.Comment: 110 pages, accepted for publication on Prog. Part. Nucl. Phy

Genomic structure and insertion sites of Helicobacter pylori prophages from various geographical origins

We present the full genomic sequences, insertion sites and phylogenetic analysis of 28 prophages found in H. pylori isolates from patients of distinct disease types, ranging from gastritis to gastric cancer, and geographic origins, covering most continents. The gentic diversity of H pylori is known to be influenced by these genomic elements including prophages who’s geneomes range from 22.6 to 33.0 Kbp. There was a high conservation of integration site shared in over 50% of cases with greater than 40% or prophage genomes harbouring insertion sequences (IS). Furthermore prophage genomes present a robust phylogeographic pattern, revealing four distinct clusters: one African, one Asian and two European prophage populations. There was evidence of recombination within the genome of some prophages, which resulted in genome mosaics composed by different populations, which may yield additional H. pylori phenotypes

Automated DNA Sequence-Based Early Warning System for the Detection of Methicillin-Resistant Staphylococcus aureus Outbreaks

BACKGROUND: The detection of methicillin-resistant Staphylococcus aureus (MRSA) usually requires the implementation of often rigorous infection-control measures. Prompt identification of an MRSA epidemic is crucial for the control of an outbreak. In this study we evaluated various early warning algorithms for the detection of an MRSA cluster. METHODS AND FINDINGS: Between 1998 and 2003, 557 non-replicate MRSA strains were collected from staff and patients admitted to a German tertiary-care university hospital. The repeat region of the S. aureus protein A (spa) gene in each of these strains was sequenced. Using epidemiological and typing information for the period 1998–2002 as reference data, clusters in 2003 were determined by temporal-scan test statistics. Various early warning algorithms (frequency, clonal, and infection control professionals [ICP] alerts) were tested in a prospective analysis for the year 2003. In addition, a newly implemented automated clonal alert system of the Ridom StaphType software was evaluated. A total of 549 of 557 MRSA were typeable using spa sequencing. When analyzed using scan test statistics, 42 out of 175 MRSA in 2003 formed 13 significant clusters (p < 0.05). These clusters were used as the “gold standard” to evaluate the various algorithms. Clonal alerts (spa typing and epidemiological data) were 100% sensitive and 95.2% specific. Frequency (epidemiological data only) and ICP alerts were 100% and 62.1% sensitive and 47.2% and 97.3% specific, respectively. The difference in specificity between clonal and ICP alerts was not significant. Both methods exhibited a positive predictive value above 80%. CONCLUSIONS: Rapid MRSA outbreak detection, based on epidemiological and spa typing data, is a suitable alternative for classical approaches and can assist in the identification of potential sources of infection

(Bio)ética e Atenção Primária à Saúde: estudo preliminar nas Clínicas da Família no município do Rio de Janeiro, Brasil

Resumo A Estratégia Saúde da Família (ESF) – iniciada como Programa de Saúde da Família (PSF), em 1994 – vem sendo pensada e trabalhada, no Brasil, como lógica prioritária para reorganização da Atenção Primária à Saúde (APS). A transformação do modelo hegemônico de APS em ESF tem promovido várias mudanças no modo de trabalho em saúde, cujos impactos em diferentes esferas – por exemplo, (bio)éticas – ainda precisam ser elucidados. Nesse contexto, realizou-se a presente investigação, caracterizada como estudo exploratório e dirigida ao mapeamento dos principais problemas (bio)éticos identificados pelos trabalhadores da APS do município do RJ. Para isso, utilizou-se um questionário – aplicado aos profissionais das Clínicas da Família (CF) – para coleta de informações, procedendo-se a análise de conteúdo, de acordo com o proposto por Bardin. O trabalho na APS no contexto da CF, possui particularidades em termos das relações (bio)éticas estabelecidas nesse nível de atenção à saúde. Assim, a proposição de novos referenciais teóricos e o desenvolvimento de ações educativas usualmente utilizadas para a abordagem das questões tornam-se extremamente necessários

Estimation of tail risk based on extreme expectiles

We use tail expectiles to estimate alternative measures to the Value at Risk (VaR) and Marginal Expected Shortfall (MES), two instruments of risk protection of utmost importance in actuarial science and statistical _nance. The concept of expectiles is a least squares analogue of quantiles. Both are M-quantiles as the minimizers of an asymmetric convex loss function, but expectiles are the only M-quantiles that are coherent risk measures. Moreover, expectiles de_ne the only coherent risk measure that is also elicitable. The estimation of expectiles has not, however, received any attention yet from the perspective of extreme values. Two estimation methods are proposed here, either making use of quantiles or relying directly on least asymmetrically weighted squares. A main tool is to _rst estimate large values of expectile-based VaR and MES located within the range of the data, and then to extrapolate the obtained estimates to the very far tails. We establish the limit distributions of both of the resulting intermediate and extreme estimators. We show via a detailed simulation study the good performance of the procedures, and present concrete applications to medical insurance data and three large US investment banks

Appropriate age range for introduction of complementary feeding into an infant’s diet

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