Corrosion protection of aluminum alloys in contact with other metals

Study establishes the quality of chemical and galvanized protection afforded by anodized and aldozided coatings applied to test panels of various aluminum alloys. The test panels, placed in firm contact with panels of titanium alloys, were subjected to salt spray tests and visually examined for corrosion effect

Effects of mixing on evolution of hydrocarbon ratios in the troposphere

Nonmethane hydrocarbon (NMHC) concentration ratios provide useful indicators of tropospheric oxidation and transport processes. However, the influences of both photochemical and mixing processes are inextricably linked in the evolution of these ratios. We present a model for investigating these influences by combining the transport treatment of the Lagrangian particle dispersion model FLEXPART with an ultrasimple (i.e., constant OH concentration) chemical treatment. Required model input includes NMHC emission ratios, but not ad hoc assumed background NMHC concentrations. The model results give NMHC relationships that can be directly compared, in a statistical manner, with measurements. The measured concentration ratios of the longest-lived alkanes show strong deviations from purely kinetic behavior, which the model nicely reproduces. In contrast, some measured aromatic ratio relationships show even stronger deviations that are not well reproduced by the model for reasons that are not understood. The model-measurement comparisons indicate that the interaction of mixing and photochemical processing prevent a simple interpretation of "photochemical age," but that the average age of any particular NMHC can be well defined and can be approximated by a properly chosen and interpreted NMHC ratio. In summary, the relationships of NMHC concentration ratios not only yield useful measures of photochemical processing in the troposphere, but also provide useful test of the treatment of mixing and chemical processing in chemical transport models. Copyright 2007 by the American Geophysical Union

Refactoring, reengineering and evolution: paths to Geant4 uncertainty quantification and performance improvement

Ongoing investigations for the improvement of Geant4 accuracy and computational performance resulting by refactoring and reengineering parts of the code are discussed. Issues in refactoring that are specific to the domain of physics simulation are identified and their impact is elucidated. Preliminary quantitative results are reported.Comment: To be published in the Proc. CHEP (Computing in High Energy Physics) 201

Probing the outer edge of an accretion disk : a Her X-1 turn-on observed with RXTE

We present the analysis of Rossi X-ray Timing Explorer (RXTE) observations of the turn-on phase of a 35 day cycle of the X-ray binary Her X-1. During the early phases of the turn-on, the energy spectrum is composed of X-rays scattered into the line of sight plus heavily absorbed X-rays. The energy spectra in the 3–17 keV range can be described by a partial covering model, where one of the components is influenced by photoelectric absorption and Thomson scattering in cold material plus an iron emission line at 6.5 keV. In this paper we show the evolution of spectral parameters as well as the evolution of the pulse profile during the turn-on. We describe this evolution using Monte Carlo simulations which self-consistently describe the evolution of the X-ray pulse profile and of the energy spectrum

Quantifying the unknown: issues in simulation validation and their experimental impact

The assessment of the reliability of Monte Carlo simulations is discussed, with emphasis on uncertainty quantification and the related impact on experimental results. Methods and techniques to account for epistemic uncertainties, i.e. for intrinsic knowledge gaps in physics modeling, are discussed with the support of applications to concrete experimental scenarios. Ongoing projects regarding the investigation of epistemic uncertainties in the Geant4 simulation toolkit are reported.Comment: To be published in the Proceedings of the 13th ICATPP Conference on Astroparticle, Particle, Space Physics and Detectors for Physics Applications, Villa Olmo, Como, 3-7 October 201

Initial management of and outcome in patients with pneumococcal bacteremia: a retrospective study at a Swiss university hospital, 2003-2009

Purpose: The aim of this quality control study was to assess the time to initial diagnostic procedures and the time to the first dose of antibiotics in patients with pneumococcal bacteremia, and to investigate whether the timeliness of these interventions influenced outcome. Methods: We retrospectively studied patient characteristics, chronological sequence of diagnostic and therapeutic steps, and the course of disease of all patients with pneumococcal bacteremia at a Swiss university hospital between 2003 and 2009, and we analyzed associations between these factors and the length of hospital stay (LOS) and mortality. Results: A total of 102 episodes of pneumococcal bacteremia in 98 patients were analyzed, of whom 15.7% died during hospitalization. The median time (interquartile range [IQR]) to the first antibiotic dose was 4.0 (2.0-5.9)h, and the median times (IQR]) to blood cultures, chest radiograph, lumbar puncture, and brain computed tomography (CT) scan or magnetic resonance imaging (MRI) were 1.4 (0.5-3.3), 2.5 (1.2-4.2), 4.2 (2.7-7.2), and 2.3 (0.6-6.2)h, respectively. The time to diagnostic procedures and therapy were not associated with LOS or death. Risk factors for death in the univariable analysis were: Charlson comorbidity index [odds ratio [OR] (95% confidence interval) per unit increase, 1.3 (1.1-1.6)], neutropenia [OR 10.1 (2.0-51.0)], human immunodeficiency virus (HIV) infection [OR 3.9 (1.1-13.8)], chronic respiratory disease [OR 4.4 (1.2-16.0)], chronic liver disease [OR 3.2 (1.0-9.7)], smoking [OR 3.8 (1.1-13.5)], injection drug use [OR 9.7 (1.5-63.7)], and antibiotic therapy within 6months before admission [OR 4.0 (1.3-12.5)]. The multivariable analysis revealed age >60years (P=0.048) and alcoholism (P=0.009) as risks for prolonged LOS. Conclusions: The outcome of pneumococcal bacteremia may be more influenced by patient characteristics than by minor differences in the timeliness of initial diagnostic and therapeutic measures within the first several hours after hospital admissio