The Galactic Center Black Hole Laboratory

The super-massive 4 million solar mass black hole Sagittarius~A* (SgrA*) shows flare emission from the millimeter to the X-ray domain. A detailed analysis of the infrared light curves allows us to address the accretion phenomenon in a statistical way. The analysis shows that the near-infrared flare amplitudes are dominated by a single state power law, with the low states in SgrA* limited by confusion through the unresolved stellar background. There are several dusty objects in the immediate vicinity of SgrA*. The source G2/DSO is one of them. Its nature is unclear. It may be comparable to similar stellar dusty sources in the region or may consist predominantly of gas and dust. In this case a particularly enhanced accretion activity onto SgrA* may be expected in the near future. Here the interpretation of recent data and ongoing observations are discussed.Comment: 30 pages - 7 figures - accepted for publication by Springer's "Fundamental Theories of Physics" series; summarizing GC contributions of 2 conferences: 'Equations of Motion in Relativistic Gravity' at the Physikzentrum Bad Honnef, Bad Honnef, Germany, (Feb. 17-23, 2013) and the COST MP0905 'The Galactic Center Black Hole Laboratory' Granada, Spain (Nov. 19 - 22, 2013

Applying Harmonic Optical Microscopy for Spatial Alignment of Atrial Collagen Fibers

BACKGROUND: Atrial fibrosis creates a vulnerable tissue for atrial fibrillation (AF), but the spatial disarray of collagen fibers underlying atrial fibrosis is not fully elucidated. OBJECTIVE: This study hypothesizes that harmonics optical microscopy can illuminate the spatial mal-alignment of collagen fibers in AF via a layer-by-layer approach. PATIENTS AND METHODS: Atrial tissues taken from patients who underwent open-heart surgery were examined by harmonics optical microscopy. Using the two-dimensional Fourier transformation method, a spectral-energy description of image texture was constituted and its entropy was used to quantify the mal-alignment of collagen fibers. The amount of collagen fiber was derived from its area ratio to total atrial tissue in each image. Serum C-terminal pro-collagen pro-peptide (CICP), pro-matrix metalloproteinase-1 (pro-MMP-1), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were also evaluated. RESULTS: 46 patients were evaluated, including 20 with normal sinus rhythm and 26 with AF. The entropy of spectral-energy distribution of collagen alignment was significantly higher in AF than that in sinus rhythm (3.97 ± 0.33 vs. 2.80 ± 0.18, p<0.005). This difference was more significant in the permanent AF group. The amount of collagen was also significantly higher in AF patients (0.39 ± 0.13 vs. 0.18 ± 0.06, p<0.005) but serum markers of cardiac fibrosis were not significantly different between the two groups. CONCLUSIONS: Harmonics optical microscopy can quantify the spatial mal-alignment of collagen fibers in AF. The entropy of spectral-energy distribution of collagen alignment is a potential tool for research in atrial remodeling

GPS constraints on deformation in northern Central America from 1999 to 2017, Part 1 – Time-dependent modelling of large regional earthquakes and their post-seismic effects

We use continuous and campaign measurements from 215 GPS sites in northern Central America and southern Mexico to estimate coseismic and afterslip solutions for the 2009 Mw = 7.3 Swan Islands fault strike-slip earthquake and the 2012 Mw = 7.3 El Salvador and Mw = 7.4 Guatemala thrust-faulting earthquakes on the Middle America trench. Our simultaneous, time-dependent inversion of more than 350 000 daily GPS site positions gives the first jointly consistent estimates of the coseismic slips for all three earthquakes, their combined time-dependent post-seismic effects and secular station velocities corrected for both the coseismic and post-seismic deformation. Our geodetic slip solutions for all three earthquakes agree with previous estimates that were derived via static coseismic-offset modelling. Our time-dependent model, which attributes all transient post-seismic deformation to earthquake afterslip, fits nearly all of the continuous GPS site position time-series within their severalmillimetre position noise. Afterslip moments for the three earthquakes range from 35 to 140 per cent of the geodetic coseismic moments, with the largest afterslip estimated for the 2012 El Salvador earthquake along the weakly coupled El Salvador trench segment. Forward modelling of viscoelastic deformation triggered by all three earthquakes for a range of assumed mantle and lower crustal viscosities suggests that it accounts for under 20 per cent of the observed post-seismic deformation and possibly under 10 per cent

Influence of toilet access on antiretroviral adherence intention among pregnant and breastfeeding women who are HIV-positive and enrolled in Option B.

We investigated the influence of toilet access on intention to adhere to antiretroviral therapy (ART) among women who are HIV-positive and enrolled in Option B+. A convenience sample of 150 women residing in Lusaka (urban) and Sinazongwe (rural) Districts of Zambia were recruited. if they were seeking pre- or post-natal care and were enrolled in Option B+. Intention to adhere to ART was assessed using four questions based on the Theory of Planned Behavior; the median score was used to distinguish high intention from low intention. Descriptive statistics were used to characterize access to toilet facilities and ART adherence intention in the entire sample and by rural and urban districts in Zambia. There was no significant difference (p = .19) between rural and urban women's access to a flush toilet. After adjusting for toilet access, however, rural women were significantly less likely to be in the high adherence intention group (PR = 0.80, 95% CI 0.71-0.90, p &lt; .001) but access to a flush toilet was associated with adherence intention (PR = 1.14, 95% CI (1.00 - 1.30). Community-led total sanitation in Zambia could increase ART adherence intention

Influence of toilet access on antiretroviral adherence intention among pregnant and breastfeeding women who are HIV-positive and enrolled in Option B.

We investigated the influence of toilet access on intention to adhere to antiretroviral therapy (ART) among women who are HIV-positive and enrolled in Option B+. A convenience sample of 150 women residing in Lusaka (urban) and Sinazongwe (rural) Districts of Zambia were recruited. if they were seeking pre- or post-natal care and were enrolled in Option B+. Intention to adhere to ART was assessed using four questions based on the Theory of Planned Behavior; the median score was used to distinguish high intention from low intention. Descriptive statistics were used to characterize access to toilet facilities and ART adherence intention in the entire sample and by rural and urban districts in Zambia. There was no significant difference (p = .19) between rural and urban women's access to a flush toilet. After adjusting for toilet access, however, rural women were significantly less likely to be in the high adherence intention group (PR = 0.80, 95% CI 0.71-0.90, p &lt; .001) but access to a flush toilet was associated with adherence intention (PR = 1.14, 95% CI (1.00 - 1.30). Community-led total sanitation in Zambia could increase ART adherence intention

Impact of attitudes and beliefs on antiretroviral treatment adherence intention among HIV-positive pregnant and breastfeeding women in Zambia.

ObjectiveThe aim of this study was to investigate if attitudes or behavioral beliefs about antiretroviral therapy (ART) influence ART adherence intention among pregnant and breastfeeding women in Zambia.MethodsWe recruited 150 HIV-positive women receiving ART in urban (Lusaka) and rural (Sinazongwe) districts of Zambia. Generalized modified Poisson regression models were used to assess the extent to which adherence intention was influenced by attitude toward ART or behavioral beliefs about ART.ResultsIntention to adhere to ART differed significantly by income, knowledge about HIV transmission, attitudes, and behavioral beliefs (all Ps &lt; .05). In addition, strong intention to adhere to ART differed by urban (69%) and rural (31%) place of residence (P ≤ .01). In adjusted models, women in the weak adherence intention group were more likely to be older, have less knowledge about HIV transmission, and have a more negative attitude toward ART (PR 0.74; 95% CI 0.67-0.82). Behavioral belief about ART, however, was significant in unadjusted model (PR 0.85; 95% CI 0.76-0.94) but not significant after adjusting for covariates such as age, knowledge of transmission, and district locality.ConclusionCompared to behavioral beliefs, attitudes about ART were more influential for intention to adhere. This knowledge will help inform effective and appropriate ART counseling for pregnant and breastfeeding women at different points along their ART time course

Impact of attitudes and beliefs on antiretroviral treatment adherence intention among HIV-positive pregnant and breastfeeding women in Zambia.

ObjectiveThe aim of this study was to investigate if attitudes or behavioral beliefs about antiretroviral therapy (ART) influence ART adherence intention among pregnant and breastfeeding women in Zambia.MethodsWe recruited 150 HIV-positive women receiving ART in urban (Lusaka) and rural (Sinazongwe) districts of Zambia. Generalized modified Poisson regression models were used to assess the extent to which adherence intention was influenced by attitude toward ART or behavioral beliefs about ART.ResultsIntention to adhere to ART differed significantly by income, knowledge about HIV transmission, attitudes, and behavioral beliefs (all Ps &lt; .05). In addition, strong intention to adhere to ART differed by urban (69%) and rural (31%) place of residence (P ≤ .01). In adjusted models, women in the weak adherence intention group were more likely to be older, have less knowledge about HIV transmission, and have a more negative attitude toward ART (PR 0.74; 95% CI 0.67-0.82). Behavioral belief about ART, however, was significant in unadjusted model (PR 0.85; 95% CI 0.76-0.94) but not significant after adjusting for covariates such as age, knowledge of transmission, and district locality.ConclusionCompared to behavioral beliefs, attitudes about ART were more influential for intention to adhere. This knowledge will help inform effective and appropriate ART counseling for pregnant and breastfeeding women at different points along their ART time course