1,714 research outputs found
Radiation tests of the Silicon Drift Detectors for LOFT
During the three years long assessment phase of the LOFT mission, candidate
to the M3 launch opportunity of the ESA Cosmic Vision programme, we estimated
and measured the radiation damage of the silicon drift detectors (SDDs) of the
satellite instrumentation. In particular, we irradiated the detectors with
protons (of 0.8 and 11 MeV energy) to study the increment of leakage current
and the variation of the charge collection efficiency produced by the
displacement damage, and we "bombarded" the detectors with hypervelocity dust
grains to measure the effect of the debris impacts. In this paper we describe
the measurements and discuss the results in the context of the LOFT mission.Comment: Proc. SPIE 9144, Space Telescopes and Instrumentation 2014:
Ultraviolet to Gamma Ray, 91446
Au/TiO2(110) interfacial reconstruction stability from ab initio
We determine the stability and properties of interfaces of low-index Au
surfaces adhered to TiO2(110), using density functional theory energy density
calculations. We consider Au(100) and Au(111) epitaxies on rutile TiO2(110)
surface, as observed in experiments. For each epitaxy, we consider several
different interfaces: Au(111)//TiO2(110) and Au(100)//TiO2(110), with and
without bridging oxygen, Au(111) on 1x2 added-row TiO2(110) reconstruction, and
Au(111) on a proposed 1x2 TiO reconstruction. The density functional theory
energy density method computes the energy changes on each of the atoms while
forming the interface, and evaluates the work of adhesion to determine the
equilibrium interfacial structure.Comment: 20 pages, 11 figure
Time connectedness of fear
This paper examines the interconnection between four implied volatility indices representative of the investors' consensus view of expected stock market volatility at different maturities during the period January 3, 2011-May 4, 2018. To this end, we first perform a static analysis to measure the total volatility connectedness in the entire period using a framework proposed by Diebold and Yilmaz (2014). Second, we apply a dynamic analysis to evaluate both the net directional connectedness for each market using the TVP-VAR connectedness approach developed by Antonakakis and Gabauer (2017). Our results suggest that a 72.27%, of the total variance of the forecast errors is explained by shocks across the examined investor time horizons, indicating that the remainder 27.73% of the variation is due to idiosyncratic shocks. Furthermore, we find that volatility connectedness varies over time, with a surge during periods of increasing economic and financial instability. Finally, we also document a superior performance of the TVP-VAR approach to connectedness respect to the original one proposed by Diebold and Yilmaz (2014
Relationship Between Non-Hodgkin's Lymphoma and Blood Levels of Epstein-Barr Virus in Children in North-Western Tanzania: A Case Control Study.
Non-Hodgkin's Lymphomas (NHL) are common in African children, with endemic Burkitt's lymphoma (BL) being the most common subtype. While the role of Epstein-Barr Virus (EBV) in endemic BL is known, no data are available about clinical presentations of NHL subtypes and their relationship to Human Immunodeficiency Virus (HIV) infection and Epstein Barr Virus (EBV) load in peripheral blood of children in north-western, Tanzania. A matched case control study of NHL subtypes was performed in children under 15 years of age and their respective controls admitted to Bugando Medical Centre, Sengerema and Shirati district designated hospitals in north-western, Tanzania, between September 2010 and April 2011. Peripheral blood samples were collected on Whatman 903 filter papers and EBV DNA levels were estimated by multiplex real-time PCR. Clinical and laboratory data were collected using a structured data collection tool and analysed using chi-square, Fisher and Wilcoxon rank sum tests where appropriate. The association between NHL and detection of EBV in peripheral blood was assessed using conditional logistic regression model and presented as odds ratios (OR) and 95% confidence intervals (CI). A total of 35 NHL cases and 70 controls matched for age and sex were enrolled. Of NHLs, 32 had BL with equal distribution between jaw and abdominal tumour, 2 had large B cell lymphoma (DLBCL) and 1 had NHL-not otherwise specified (NHL-NOS). Central nervous system (CNS) presentation occurred only in 1 BL patient; 19 NHLs had stage I and II of disease. Only 1 NHL was found to be HIV-seropositive. Twenty-one of 35 (60%) NHL and 21 of 70 (30%) controls had detectable EBV in peripheral blood (OR = 4.77, 95% CI 1.71 - 13.33, p = 0.003). In addition, levels of EBV in blood were significantly higher in NHL cases than in controls (p = 0.024). BL is the most common childhood NHL subtype in north-western Tanzania. NHLs are not associated with HIV infection, but are strongly associated with EBV load in peripheral blood. The findings suggest that high levels of EBV in blood might have diagnostic and prognostic relevance in African children
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