RXTE Spectral Observations of the 1996-97 Outburst of the Microquasar GRO J1655-40

Excellent coverage of the entire 16-month 1996-97 outburst cycle of GRO J1655-40 was provided by RXTE. We present a full spectral analysis of these data, which includes 52 PCA spectra from 2.5-20 keV and HEXTE spectra above 20 keV. We also include a nearly continuous ASM light curve with several intensity measurements per day. The data are interpreted in the context of the multicolor blackbody disk/power-law model. The source is observed in the very high, high/soft, and low/hard outburst states. During the very high state, the source exhibits intense hard flares on time scales of hours to days which are correlated with changes in both the fitted temperature and radius of the inner accretion disk. During the high/soft state, the spectrum is dominated by the soft thermal emission from the accretion disk with spectral parameters that suggest approximately constant inner disk radius and temperature. We find that a tight relationship exists between the observed inner radius of the disk and the flux in the power-law component. During intense hard flares, the inner disk radius is observed to decrease by as much as a factor of three on a time scale of days. The apparent decrease of the inner disk radius observed during the flares may be due to the failure of the multicolor disk model caused by a steepening of the radial temperature profile in the disk coupled with increased spectral hardening and not physical changes of the inner disk radius. Assuming that our spectral model is valid during periods of weak power-law emission, our most likely value for the inner disk radius implies a* < 0.7. Such a low value for the black hole angular momentum is inconsistent with the relativistic frame dragging and the `diskoseismic' models as interpretations for the 300 Hz X-ray QPO seen during some of these RXTE observations.Comment: 34 pages including 9 figures and 3 tables. Accepted for publication in the Astrophysical Journal. Our interpretation of the data and the main conclusions have been significantly revise

Food assistance is associated with improved body mass index, food security and attendance at clinic in an HIV program in central Haiti: a prospective observational cohort study

<p>Abstract</p> <p>Background</p> <p>Few data are available to guide programmatic solutions to the overlapping problems of undernutrition and HIV infection. We evaluated the impact of food assistance on patient outcomes in a comprehensive HIV program in central Haiti in a prospective observational cohort study.</p> <p>Methods</p> <p>Adults with HIV infection were eligible for monthly food rations if they had any one of: tuberculosis, body mass index (BMI) <18.5kg/m², CD4 cell count <350/mm³(in the prior 3 months) or severe socio-economic conditions. A total of 600 individuals (300 eligible and 300 ineligible for food assistance) were interviewed before rations were distributed, at 6 months and at 12 months. Data collected included demographics, BMI and food insecurity score (range 0 - 20).</p> <p>Results</p> <p>At 6- and 12-month time-points, 488 and 340 subjects were eligible for analysis. Multivariable analysis demonstrated that at 6 months, food security significantly improved in those who received food assistance versus who did not (-3.55 vs -0.16; P < 0.0001); BMI decreased significantly less in the food assistance group than in the non-food group (-0.20 vs -0.66; P = 0.020). At 12 months, food assistance was associated with improved food security (-3.49 vs -1.89, P = 0.011) and BMI (0.22 vs -0.67, P = 0.036). Food assistance was associated with improved adherence to monthly clinic visits at both 6 (P < 0.001) and 12 months (P = 0.033).</p> <p>Conclusions</p> <p>Food assistance was associated with improved food security, increased BMI, and improved adherence to clinic visits at 6 and 12 months among people living with HIV in Haiti and should be part of routine care where HIV and food insecurity overlap.</p

Information management to enable personalized medicine: stakeholder roles in building clinical decision support

<p>Abstract</p> <p>Background</p> <p>Advances in technology and the scientific understanding of disease processes are presenting new opportunities to improve health through individualized approaches to patient management referred to as personalized medicine. Future health care strategies that deploy genomic technologies and molecular therapies will bring opportunities to prevent, predict, and pre-empt disease processes but will be dependent on knowledge management capabilities for health care providers that are not currently available. A key cornerstone to the potential application of this knowledge will be effective use of electronic health records. In particular, appropriate clinical use of genomic test results and molecularly-targeted therapies present important challenges in patient management that can be effectively addressed using electronic clinical decision support technologies.</p> <p>Discussion</p> <p>Approaches to shaping future health information needs for personalized medicine were undertaken by a work group of the American Health Information Community. A needs assessment for clinical decision support in electronic health record systems to support personalized medical practices was conducted to guide health future development activities. Further, a suggested action plan was developed for government, researchers and research institutions, developers of electronic information tools (including clinical guidelines, and quality measures), and standards development organizations to meet the needs for personalized approaches to medical practice. In this article, we focus these activities on stakeholder organizations as an operational framework to help identify and coordinate needs and opportunities for clinical decision support tools to enable personalized medicine.</p> <p>Summary</p> <p>This perspective addresses conceptual approaches that can be undertaken to develop and apply clinical decision support in electronic health record systems to achieve personalized medical care. In addition, to represent meaningful benefits to personalized decision-making, a comparison of current and future applications of clinical decision support to enable individualized medical treatment plans is presented. If clinical decision support tools are to impact outcomes in a clear and positive manner, their development and deployment must therefore consider the needs of the providers, including specific practice needs, information workflow, and practice environment.</p

X-ray Nova XTE J1550-564: RXTE Spectral Observations

Excellent coverage of the 1998 outburst of the X-ray Nova XTE J1550-564 was provided by the Rossi X-ray Timing Explorer. XTE J1550-564 exhibited an intense (6.8 Crab) flare on 1998 September 19 (UT), making it the brightest new X-ray source observed with RXTE. We present a spectral analysis utilizing 60 Proportional Counter Array spectra from 2.5-20 keV spanning 71 days, and a nearly continuous All Sky Monitor light curve. The spectra were fit to a model including multicolor blackbody disk and power-law components. XTE J1550-564 is observed in the very high, high/soft, and intermediate canonical outburst states of Black Hole X-ray Novae.Comment: 14 pages including 1 table and 4 figures, Accepted to ApJ Letter

HIV-free survival and morbidity among formula-fed infants in a prevention of mother-to-child transmission of HIV program in rural Haiti

<p>Abstract</p> <p>Background</p> <p>Partners In Health (PIH) works with the Ministry of Health to provide comprehensive health services in Haiti. Between 1994 and 2009, PIH recommended exclusive formula feeding in the prevention of mother-to-child transmission (PMTCT) of HIV program and provided support to implement this strategy. We conducted this study to assess HIV-free survival and prevalence of diarrhea and malnutrition among infants in our PMTCT program in rural Haiti where exclusive formula feeding was supported.</p> <p>Methods</p> <p>We reviewed medical charts of PMTCT mother-infant pairs at PIH between November 2004 and August 2006 through a retrospective longitudinal study and cross-sectional survey. We performed household surveys for each pair and at control households matched by infant's age and gender.</p> <p>Results</p> <p>254 mother-infant pairs were included. 15.3% of infants were low birth weight; most births occurred at home (68.8%). 55.9% of households had no latrine; food insecurity was high (mean score of 18; scale 0-27, SD = 5.3). HIV-free survival at 18 months was 90.6%. Within the cohort, 9 children (3.5%) were HIV-infected and 17 (6.7%) died. Community controls were more likely to be breastfed (P = 0.003) and more likely to introduce food early (P = 0.003) than PMTCT-program households. There was no difference in moderate malnutrition (Z score ≤ 2 SD) between PMTCT and community groups after controlling for guardian's education, marital status, and food insecurity (OR = 1.05; 95% CI: 0.67, 1.64; P = 0.84). Diarrhea was 2.9 times more prevalent among community children than PMTCT infants (30.3% vs. 12.2%; P < 0.0001).</p> <p>Conclusions</p> <p>In a PIH-supported program in rural Haiti that addressed socioeconomic barriers to ill-health, breast milk substitution was safe, acceptable and feasible for PMTCT for HIV-infected women choosing this option.</p

Complete RXTE Spectral Observations of the Black Hole X-ray Nova XTE J1550-564

We report on the X-ray spectral behavior of the exceptionally bright X-ray nova XTE J1550-564 during its 1998-99 outburst. Our study is based on 209 pointed observations using the PCA and HEXTE instruments onboard the Rossi X-ray Timing Explorer spanning 250 days and covering the entire double-peaked eruption that occurred from 1998 September until 1999 May. The spectra are fit to a model including multicolor blackbody disk and power-law components. The source is observed in the very high and high/soft outburst states of black hole X-ray novae. During the very high state, when the power-law component dominated the spectrum, the inner disk radius is observed to vary by more than an order of magnitude; the radius decreased by a factor of 16 in one day during a 6.8 Crab flare. If the larger of these observed radii is taken to be the last stable orbit, then the smaller observed radius would imply that the inner edge of the disk is inside the event horizon! However, we conclude that the apparent variations of the inner disk radius observed during periods of increased power-law emission are probably caused by the failure of the multicolor disk/power-law model; the actual physical radius of the inner disk may remain fairly constant. This interpretation is supported by the fact that the observed inner disk radius remains approximately constant over 120 days in the high state, when the power-law component is weak, even though the disk flux and total flux vary by an order of magnitude. The mass of the black hole inferred by equating the approximately constant inner disk radius observed in the high/soft state with the last stable orbit for a Schwarzschild black hole is M_BH = 7.4 M_sun (D/6 kpc) (cos i)^{-1/2}.Comment: Submitted to ApJ, 20 pages including 6 figures + 4 large table

Spot form of net blotch resistance in barley is under complex genetic control

Key message: Evaluation of resistance toPyrenophora teresf.maculatain barley breeding populations via association mapping revealed a complex genetic architecture comprising a mixture of major and minor effect genes. Abstract: In the search for stable resistance to spot form of net blotch (Pyrenophora teres f. maculata, SFNB), association mapping was conducted on four independent barley (Hordeum vulgare L.) breeding populations comprising a total of 898 unique elite breeding lines from the Northern Region Barley Breeding Program in Australia for discovery of quantitative trait loci (QTL) influencing resistance at seedling and adult plant growth stages. A total of 29 significant QTL were validated across multiple breeding populations, with 22 conferring resistance at both seedling and adult plant growth stages. The remaining 7 QTL conferred resistance at either seedling (2 QTL) or adult plant (5 QTL) growth stages only. These 29 QTL represented 24 unique genomic regions, of which five were found to co-locate with previously identified QTL for SFNB. The results indicated that SFNB resistance is controlled by a large number of QTL varying in effect size with large effects QTL on chromosome 7H. A large proportion of the QTL acted in the same direction for both seedling and adult responses, suggesting that phenotypic selection for SFNB resistance performed at either growth stage could achieve adequate levels of resistance. However, the accumulation of specific resistance alleles on several chromosomes must be considered in molecular breeding selection strategies

Nucleation of PP-Branes and Fundamental Strings

We construct a solution to the low-energy string equations of motion in five dimensions that describes a circular loop of fundamental string exponentially expanding in a background electric $H$-field. Euclideanising this gives an instanton for the creation of a loop of fundamental string in a background $H$-field, and we calculate the rate of nucleation. Solutions describing magnetically charged strings and $p$-branes, where the gauge field comes from Kaluza-Klein reduction on a circle, are also constructed. It is known that a magnetic flux tube in four (reduced) spacetime dimensions is unstable to the pair creation of Kaluza-Klein monopoles. We show that in $(4+p)$ dimensions, magnetic $(p+1)$ ``fluxbranes" are unstable to the nucleation of a magnetically charged spherical $p$-brane. In ten dimensions the instanton describes the nucleation of a Ramond-Ramond magnetically charged six-brane in type IIA string theory. We also find static solutions describing spherical charged $p$-branes or fundamental strings held in unstable equilibrium in appropriate background fields. Instabilities of intersecting magnetic fluxbranes are also discussed.Comment: 28 pages, harvmac (b), reference added, typos correcte

Dendritic Cell Mediated Delivery of Plasmid DNA Encoding LAMP/HIV-1 Gag Fusion Immunogen Enhances T Cell Epitope Responses in HLA DR4 Transgenic Mice

This report describes the identification and bioinformatics analysis of HLA-DR4-restricted HIV-1 Gag epitope peptides, and the application of dendritic cell mediated immunization of DNA plasmid constructs. BALB/c (H-2d) and HLA-DR4 (DRA1*0101, DRB1*0401) transgenic mice were immunized with immature dendritic cells transfected by a recombinant DNA plasmid encoding the lysosome-associated membrane protein-1/HIV-1 Gag (pLAMP/gag) chimera antigen. Three immunization protocols were compared: 1) primary subcutaneous immunization with 1×105 immature dendritic cells transfected by electroporation with the pLAMP/gag DNA plasmid, and a second subcutaneous immunization with the naked pLAMP/gag DNA plasmid; 2) primary immunization as above, and a second subcutaneous immunization with a pool of overlapping peptides spanning the HIV-1 Gag sequence; and 3) immunization twice by subcutaneous injection of the pLAMP/gag DNA plasmid. Primary immunization with pLAMP/gag-transfected dendritic cells elicited the greatest number of peptide specific T-cell responses, as measured by ex vivo IFN-γ ELISpot assay, both in BALB/c and HLA-DR4 transgenic mice. The pLAMP/gag-transfected dendritic cells prime and naked DNA boost immunization protocol also resulted in an increased apparent avidity of peptide in the ELISpot assay. Strikingly, 20 of 25 peptide-specific T-cell responses in the HLA-DR4 transgenic mice contained sequences that corresponded, entirely or partially to 18 of the 19 human HLA-DR4 epitopes listed in the HIV molecular immunology database. Selection of the most conserved epitope peptides as vaccine targets was facilitated by analysis of their representation and variability in all reported sequences. These data provide a model system that demonstrates a) the superiority of immunization with dendritic cells transfected with LAMP/gag plasmid DNA, as compared to naked DNA, b) the value of HLA transgenic mice as a model system for the identification and evaluation of epitope-based vaccine strategies, and c) the application of variability analysis across reported sequences in public databases for selection of historically conserved HIV epitopes as vaccine targets