Latest results on Jovian disk X-rays from XMM-Newton

We present the results of a spectral study of the soft X-ray emission (0.2-2.5 keV) from low-latitude (`disk') regions of Jupiter. The data were obtained during two observing campaigns with XMM-Newton in April and November 2003. While the level of the emission remained approximately the same between April and the first half of the November observation, the second part of the latter shows an enhancement by about 40% in the 0.2-2.5 keV flux. A very similar, and apparently correlated increase, in time and scale, was observed in the solar X-ray and EUV flux. The months of October and November 2003 saw a period of particularly intense solar activity, which appears reflected in the behaviour of the soft X-rays from Jupiter's disk. The X-ray spectra, from the XMM-Newton EPIC CCD cameras, are all well fitted by a coronal model with temperatures in the range 0.4-0.5 keV, with additional line emission from Mg XI (1.35 keV) and Si XIII (1.86 keV): these are characteristic lines of solar X-ray spectra at maximum activity and during flares. The XMM-Newton observations lend further support to the theory that Jupiter's disk X-ray emission is controlled by the Sun, and may be produced in large part by scattering, elastic and fluorescent, of solar X-rays in the upper atmosphere of the planet.Comment: 17 pages, 7 figures, accepted for publication in a special issue of Planetary and Space Scienc

Invasive properties of south Indian strains of Streptococcus pyogenes in a HEp-2 cell model

The objective of this study was to consider the invasive properties of Streptococcus pyogenes in human pharyngeal epithelial cells, and to correlate these with their clinical significance. Clinical isolates of S. pyogenes obtained from blood cultures over a period of 10 years, and throat and skin isolates from a community-based study, were used in this investigation. The S. pyogenes isolates were inoculated in HEp-2 cells and subsequently treated with antibiotics to kill the extracellular bacteria. The cells were then lyzed, and a colony count was carried out to check for invasion. The throat and skin isolates had 45.7%, 25.7% and 28.5% of low, intermediate and high invasion efficiencies, respectively, while 80%, 8.6% and 11.4% of the blood isolates had low, intermediate and high invasion efficiencies. We concluded that the throat and the skin isolates from superficial infections were more invasive than the blood isolates, which is an interesting and paradoxical feature

Genetic stability of pneumococcal isolates during 35 days of human experimental carriage

Background Pneumococcal carriage is a reservoir for transmission and a precursor to pneumococcal disease. The experimental human pneumococcal carriage model provides a useful tool to aid vaccine licensure through the measurement of vaccine efficacy against carriage (VEcol). Documentation of the genetic stability of the experimental human pneumococcal carriage model is important to further strengthen confidence in its safety and conclusions, enabling it to further facilitate vaccine licensure through providing evidence of VEcol. Methods 229 isolates were sequenced from 10 volunteers in whom experimental human pneumococcal carriage was established, sampled over a period of 35 days. Multiple isolates from within a single volunteer at a single time provided a deep resolution for detecting variation. HiSeq data from the isolates were mapped against a PacBio reference of the inoculum to call variable sites. Results The observed variation between experimental carriage isolates was minimal with the maximum SNP distance between any isolate and the reference being 3 SNPs. Conclusion The low-level variation described provides evidence for the stability of the experimental human pneumococcal carriage model over 35 days, which can be reliably and confidently used to measure VEcol and aid future progression of pneumococcal vaccination

Outbursts from IGR J17473-2721

We have investigated the outbursts of IGR J17473-2721. We analyzed all available observations carried out by RXTE on IGR J17473-2721 during its later outburst and as well all the available SWIFT/BAT data. The flux of the latter outburst rose in ~ one month and then kept roughly constant for the following ~ two months. During this time period, the source was in a low/hard state. The source moved to a high/soft state within the following three days, accompanied by the occurrence of an additional outburst at soft X-rays and the end of the preceding outburst in hard X-rays. During the decay of this soft outburst, the source went back to a low/hard state within 6 days, with a luminosity 4 times lower than the first transition. This shows a full cycle of the hysteresis in transition between the hard and the soft states. The fact that the flux remained roughly constant for ~ two months at times prior to the spectral transition to a high/soft state might be regarded as the result of balancing the evaporation of the inner disk and the inward accretion flow, in a model in which the state transition is determined by the mass flow rate. Such a balance might be broken via an additional mass flow accreting onto the inner disk, which lightens the extra soft outburst and causes the state transition. However, the possibility of an origin of the emission from the jet during this time period cannot be excluded. The spectral analysis suggests an inclined XRB system for IGR J17473-2721. Such a long-lived preceding low/hard state makes IGR J17473-2721 resemble the behavior of outbursts seen in black hole X-ray binaries like GX 339-4.Comment: A&A in pres

Investigation of a hepatitis A outbreak in children in an urban slum in Vellore,Tamil Nadu, using geographic information systems

Background & objectives: An outbreak of symptomatic viral hepatitis in children less than 10 yr of age in Vellore, south India, was investigated and the disease pattern studied using serological and epidemiological methods, supplemented by geographic information systems (GIS) mapping. Methods: Three cases of hepatitis A were identified during routine surveillance in a birth cohort House-to-house visits were undertaken to identify other symptomatic cases and samples collected for anti- HAV IgM, ELISA testing. All cases and controls were mapped and geo-referenced using Arc View GIS 3.3. Spatial clustering was investigated using SaTScan 7.0.1 software. Drinking water sources were tested for coliform counts with the most probable number technique. Results: Of the 965 children surveyed, 26 (2.78%) had jaundice between February to July 2006. From the 26 patients, 11 (42.3%) blood samples were obtained and tested for anti-HAV IgM; 10 (90.9%) were found to be positive. Water analysis showed high coliform counts in all samples. No spatial clustering of cases could be detected. Interpretation & conclusions: The outbreak was identified because of the symptomatic presentation of the cases. Our study highlighted the increasing detection of symptomatic children with hepatitis A virus infection. Water sources in the area were contaminated and may have served as the source of infection. The lack of clustering in GIS analysis could be due to the common water source

Chronic growth faltering amongst a birth cohort of Indian children begins prior to weaning and is highly prevalent at three years of age

BACKGROUND: Poor growth of children in developing countries is a major public health problem associated with mortality, morbidity and developmental delay. We describe growth up to three years of age and investigate factors related to stunting (low height-for-age) at three years of age in a birth cohort from an urban slum. METHODS: 452 children born between March 2002 and August 2003 were followed until their third birthday in three neighbouring slums in Vellore, South India. Field workers visited homes to collect details of morbidity twice a week. Height and weight were measured monthly from one month of age in a study-run clinic. For analysis, standardised z-scores were generated using the 2006 WHO child growth standards. Risk factors for stunting at three years of age were analysed in logistic regression models. A sensitivity analysis was conducted to examine the effect of missing values. RESULTS: At age three years, of 186 boys and 187 girls still under follow-up, 109 (66%, 95% Confidence interval 58-73%) boys and 93 (56%, 95% CI 49-64%) girls were stunted, 14 (8%, 95% CI 4-13%) boys and 12 (7%, 95% CI 3-11%) girls were wasted (low weight-for-height) and 72 (43%, 95% CI 36-51) boys and 66 (39%, 95% CI 31-47%) girls were underweight (low weight-for-age). In total 224/331 (68%) children at three years had at least one growth deficiency (were stunted and/or underweight and/or wasted); even as early as one month of age 186/377 (49%) children had at least one growth deficiency. Factors associated with stunting at three years were birth weight less than 2.5 kg (OR 3.63, 95% CI 1.36-9.70) 'beedi-making' (manual production of cigarettes for a daily wage) in the household (OR 1.74, 95% CI 1.05-2.86), maternal height less than 150 cm (OR 2.02, 95% CI 1.12-3.62), being stunted, wasted or underweight at six months of age (OR 1.75, 95% CI 1.05-2.93) and having at least one older sibling (OR 2.00, 95% CI 1.14-3.51). CONCLUSION: A high proportion of urban slum dwelling children had poor growth throughout the first three years of life. Interventions are needed urgently during pregnancy, early breastfeeding and weaning in this population

Critical temperature and giant isotope effect in presence of paramagnons

We reconsider the long-standing problem of the effect of spin fluctuations on the critical temperature and isotope effect in a phonon-mediated superconductor. Although the general physics of the interplay between phonons and paramagnons had been rather well understood, the existing approximate formulas fail to describe the correct behavior of $$ for general phonon and paramagnon spectra. Using a controllable approximation, we derive an analytical formula for $T_{c}$ which agrees well with exact numerical solutions of the Eliashberg equations for a broad range of parameters. Based on both numerical and analytical results, we predict a strong enhancement of the isotope effect when the frequencies of spin fluctuation and phonons are of the same order. This effect may have important consequences for near-magnetic superconductors such as MgCNi$_{3}$Comment: 5 pages, 2 figure