Evidence for a Photospheric Component in the Prompt Emission of the Short GRB120323A and its Effects on the GRB Hardness-Luminosity Relation

The short GRB 120323A had the highest flux ever detected with the Fermi/GBM. Here we study its remarkable spectral properties and their evolution using two spectral models: (i) a single emission component scenario, where the spectrum is modeled by the empirical Band function, and (ii) a two component scenario, where thermal (Planck-like) emission is observed simultaneously with a non-thermal component (a Band function). We find that the latter model fits the integrated burst spectrum significantly better than the former, and that their respective spectral parameters are dramatically different: when fit with a Band function only, the Epeak of the event is unusually soft for a short GRB, while adding a thermal component leads to more typical short GRB values. Our time-resolved spectral analysis produces similar results. We argue here that the two-component model is the preferred interpretation for GRB 120323A, based on: (i) the values and evolution of the Band function parameters of the two component scenario, which are more typical for a short GRB, and (ii) the appearance in the data of a significant hardness-intensity correlation, commonly found in GRBs, when we employee two-component model fits; the correlation is non-existent in the Band-only fits. GRB 110721A, a long burst with an intense photospheric emission, exhibits the exact same behavior. We conclude that GRB 120323A has a strong photospheric emission contribution, first time observed in a short GRB. Magnetic dissipation models are difficult to reconcile with these results, which instead favor photospheric thermal emission and fast cooling synchrotron radiation from internal shocks. Finally, we derive a possibly universal hardness-luminosity relation in the source frame using a larger set of GRBs L,i=(1.59+/-0.84).10^50 (Epeak,i)^(1.33+/-0.07) erg/s), which could be used as a possible redshift estimator for cosmology.Comment: 27 pages, 13 figures, Accepted by ApJ (April, 7th 2013

Insights into biofilm dispersal regulation from the crystal structure of the PAS-GGDEF-EAL region of RbdA from Pseudomonas aeruginosa

© 2018 American Society for Microbiology. RbdA is a positive regulator of biofilm dispersal of Pseudomonas aeruginosa. Its cytoplasmic region (cRbdA) comprises an N-terminal Per-ARNT-Sim (PAS) domain followed by a diguanylate cyclase (GGDEF) domain and an EAL domain, whose phosphodiesterase activity is allosterically stimulated by GTP binding to the GGDEF domain. We report crystal structures of cRbdA and of two binary complexes: one with GTP/Mg 2+ bound to the GGDEF active site and one with the EAL domain bound to the c-di-GMP substrate. These structures unveil a 2-fold symmetric dimer stabilized by a closely packed N-terminal PAS domain and a noncanonical EAL dimer. The autoinhibitory switch is formed by an α-helix (S-helix) immediately N-terminal to the GGDEF domain that interacts with the EAL dimerization helix (α6-E) of the other EAL monomer and maintains the protein in a locked conformation. We propose that local conformational changes in cRbdA upon GTP binding lead to a structure with the PAS domain and S-helix shifted away from the GGDEF-EAL domains, as suggested by small-angle X-ray scattering (SAXS) experiments. Domain reorientation should be facilitated by the presence of an α-helical lever (H-helix) that tethers the GGDEF and EAL regions, allowing the EAL domain to rearrange into an active dimeric conformation

Temporary exclusion of ill children from childcare centres in Switzerland: practice, problems and potential solutions.

BACKGROUND: In childcare centres, temporary exclusion of ill children, if their illness poses a risk of spread of harmful diseases to others, is a central approach to fight disease transmission. However, not all ill children need to be excluded. Previous studies suggested that childcare centre staff have difficulties in deciding whether or not to exclude an ill child, even when official ill-child guidelines are used. We aimed to describe, quantify and analyse these ambiguities and discuss potential solutions. METHODS: For this cross-sectional study, we sent postal surveys to 488 childcare centre directors in the Swiss Canton of Zurich, where no official ill-child guideline is in place. We asked for exclusion criteria for ill children and ambiguities faced when dealing with ill children. We checked whether existing guidelines provided solutions to the ambiguities identified. RESULTS: 249/488 (51%) directors responded to the survey. The most common exclusion criteria were fever (87.4%) and contagiousness (52.2%). Ambiguities were mostly caused by conjunctivitis (23.7%) and use of antipyretic drugs (22.9%). Roughly one third of the ambiguities identified could have been resolved with existing guidelines, another third if existing guidelines contained additional information. For the last third, clear written directives are difficult to formulate. CONCLUSIONS: Written recommendations may help to clarify when an ill child should temporarily be excluded. However, such a guideline should cover the topics antipyretic drugs and teething and have room for modification to local circumstances. Collaboration with a paediatrician may be of additional benefit

ACALASIA NA DOENÇA DE CHAGAS É DIFERENTE DE ACALASIA IDIOPÁTICA? EXPERIÊNCIA DO HOSPITAL DE CLÍNICAS DE PORTO ALEGRE

Objetive: The objective of this study is to evaluate the differences between achalasia in Chagas’ disease and idiopathic achalasia in patients admitted to the Hospital de Clínicas de Porto Alegre, by analyzing epidemiologic, clinic, radiologic and manometric findings.Methods: Patients referred to the Hospital de Clinicas de Porto Alegre between November 1996 and December 2001 with suspicion of achalasia, later confirmed by esophageal manometry, were included in the study. In addition to manometric and radiologic findings, patients were assessed for age, sex, symptomsand symptomatic period.Results: Among 51 patients, nine (18%) presented positive serology for Chagas’ disease and 42 (82%) presented negative serology. The latter were considered carriers of idiopathic achalasia. The mean age of patients with achalasia in Chagas’ disease was 62 ± 15 years, while the mean age in the idiopathic group was 43 ± 18 years (P < 0.02). The symptomatic period for patients with achalasia in Chagas’ disease was 74 ± 47 months, and in the idiopathic group, 49 ± 35 months (P < 0.05). Dysphagia, regurgitation, thoracic pain and weight loss, values at the lower esophageal sphincter (basal pressure, post-deglutitive relaxation pressure/duration and total length) and at the esophageal body (amplitude and duration of the post-deglutitive waves) were similar in both groups.Conclusions: The only statistically significant differences found between the two groups were age and length of the symptomatic period, significantly greater in patients with achalasia in Chagas’ disease. These data suggest a greater resistance to the symptoms in older patients.Objetivo: O presente trabalho tem como objetivo avaliar as diferenças entre a acalasia chagásica e a idiopática em pacientes do Hospital de Clínicas de Porto Alegre, através da análise de achados epidemiológicos, clínicos, radiológicos e manométricos.Métodos: Foram estudados pacientes encaminhados ao Hospital de Clínicas de Porto Alegre, entre novembro de 1996 e dezembro de 2001, com suspeita de acalasia, posteriormente, confirmada por manometria esofágica. Além das características manométricas e radiológicas, os pacientes foram avaliados quanto a idade, sexo, sintomas e tempo de evolução.Resultados: Entre 51 pacientes, nove (18%) tiveram sorologia positiva para doença de Chagas e 42 (82%) sorologia negativa. Indivíduos com sorologia negativa foram considerados portadores de acalasia idiopática. Pacientes com acalasia chagásica tinham média de idade de 62 ± 15 anos e os com idiopática 43 ± 18 anos (P < 0,02). O período de evolução dos sintomas em pacientes com acalasia chagásica foi de 74 ± 47 meses e nos idiopáticos 49 ± 35 meses (P < 0,05). Disfagia, regurgitação, dor torácica e emagrecimento, valores do esfíncter esofágico inferior (pressão basal, pressão e duração de relaxamento pós-deglutição e comprimento total) e do corpo esofágico (amplitude e duração das ondas pós-deglutição) foram similares em ambos os grupos.Conclusões: As únicas diferenças estatisticamente significativas encontradas entre os dois grupos foram a média de idade e o período de evolução dos sintomas, maiores nos pacientes chagásicos. Esses dados permitem especular sobre uma maior tolerância aos sintomas nos pacientes com idade mais avançada

Targeting the Mycobacterium ulcerans cytochrome bc1:aa3 for the treatment of Buruli ulcer

Mycobacterium ulcerans is the causative agent of Buruli ulcer, a neglected tropical skin disease that is most commonly found in children from West and Central Africa. Despite the severity of the infection, therapeutic options are limited to antibiotics with severe side effects. Here, we show that M. ulcerans is susceptible to the anti-tubercular drug Q203 and related compounds targeting the respiratory cytochrome bc; 1; :aa; 3; . While the cytochrome bc; 1; :aa; 3; is the primary terminal oxidase in Mycobacterium tuberculosis, the presence of an alternate bd-type terminal oxidase limits the bactericidal and sterilizing potency of Q203 against this bacterium. M. ulcerans strains found in Buruli ulcer patients from Africa and Australia lost all alternate terminal electron acceptors and rely exclusively on the cytochrome bc; 1; :aa; 3; to respire. As a result, Q203 is bactericidal at low dose against M. ulcerans replicating in vitro and in mice, making the drug a promising candidate for Buruli ulcer treatment

Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank

9 páginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved: the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and Conselleria de Pesca de la Xunta de GaliciaPeer reviewe