Cosmic rays in the heliosphere

The different types of cosmic ray particles and their role in the heliosphere are briefly described. The rates of various energetic particles were examined as a function of time and used to derive various differential energy gradients. The Pioneer and Voyager cosmic ray observations throughout the heliosphere are indeed giving a perspective on the three-dimensional character and size of the heliosphere. Most clearly the observations are emphasizing the role that transient variations in the outer heliosphere, and most likely the heliospheric boundary shock, play in the 11 year solar cycle modulation of cosmic rays

Maintenance Models for Systems subject to Measurable Deterioration

Complex engineering systems such as bridges, roads, flood defence structures, and power pylons play an important role in our society. Unfortunately such systems are subject to deterioration, meaning that in course of time their condition falls from higher to lower, and possibly even to unacceptable, levels. Maintenance actions such as inspection, local repair and replacement should be done to retain such systems in or restore them to acceptable operating conditions. After all, the economic consequences of malfunctioning infrastructure systems can be huge. In the life-cycle management of engineering systems, the decisions regarding the timing and the type of maintenance depend on the temporal uncertainty associated with the deterioration. Hence it is of importance to model this uncertainty. In the literature, deterioration models based on Brownian motion and gamma process have had much attention, but a thorough comparison of these models lacks. In this thesis both models are compared on several aspects, both in a theoretical as well as in an empirical setting. Moreover, they are compared with physical process models, which can capture structural insights into the underlying process. For the latter a new framework is developed to draw inference. Next, models for imperfect maintenance are investigated. Finally, a review is given for systems consisting of multiple components

Vitamin D supplementation does not improve human skeletal muscle contractile properties in insufficient young males

Vitamin D may be a regulator of skeletal muscle function, although human trials investigating this hypothesis are limited to predominantly elderly populations. We aimed to assess the effect of oral vitamin D3 in healthy young males upon skeletal muscle function

The Modified Weighted Slab Technique: Models and Results

In an attempt to understand the source and propagation of galactic cosmic rays we have employed the Modified Weighted Slab technique along with recent values of the relevant cross sections to compute primary to secondary ratios including B/C and Sub-Fe/Fe for different galactic propagation models. The models that we have considered are the disk-halo diffusion model, the dynamical halo wind model, the turbulent diffusion model and a model with minimal reacceleration. The modified weighted slab technique will be briefly discussed and a more detailed description of the models will be given. We will also discuss the impact that the various models have on the problem of anisotropy at high energy and discuss what properties of a particular model bear on this issue.Comment: LaTeX - AASTEX format, Submitted to ApJ, 8 figures, 20 page

Payload characterization for CubeSat demonstration of MEMS deformable mirrors

Coronagraphic space telescopes require wavefront control systems for high-contrast imaging applications such as exoplanet direct imaging. High-actuator-count MEMS deformable mirrors (DM) are a key element of these wavefront control systems yet have not been flown in space long enough to characterize their on-orbit performance. The MEMS Deformable Mirror CubeSat Testbed is a conceptual nanosatellite demonstration of MEMS DM and wavefront sensing technology. The testbed platform is a 3U CubeSat bus. Of the 10 x 10 x 34.05 cm (3U) available volume, a 10 x 10 x 15 cm space is reserved for the optical payload. The main purpose of the payload is to characterize and calibrate the onorbit performance of a MEMS deformable mirror over an extended period of time (months). Its design incorporates both a Shack Hartmann wavefront sensor (internal laser illumination), and a focal plane sensor (used with an external aperture to image bright stars). We baseline a 32-actuator Boston Micromachines Mini deformable mirror for this mission, though the design is flexible and can be applied to mirrors from other vendors. We present the mission design and payload architecture and discuss experiment design, requirements, and performance simulations.United States. National Aeronautics and Space Administration (Space Technology Research Fellowship

EFFECT OF LONGITUDE-DEPENDENT CLOUD COVERAGE ON EXOPLANET VISIBLE WAVELENGTH REFLECTED-LIGHT PHASE CURVES

We use a planetary albedo model to investigate variations in visible wavelength phase curves of exoplanets. Thermal and cloud properties for these exoplanets are derived using one-dimensional radiative-convective and cloud simulations. The presence of clouds on these exoplanets significantly alters their planetary albedo spectra. We confirm that non-uniform cloud coverage on the dayside of tidally locked exoplanets will manifest as changes to the magnitude and shift of the phase curve. In this work, we first investigate a test case of our model using a Jupiter-like planet, at temperatures consistent to 2.0 AU insolation from a solar type star, to consider the effect of H[subscript 2]O clouds. We then extend our application of the model to the exoplanet Kepler-7b and consider the effect of varying cloud species, sedimentation efficiency, particle size, and cloud altitude. We show that, depending on the observational filter, the largest possible shift of the phase curve maximum will be ~2°–10° for a Jupiter-like planet, and up to ~30° (~0.08 in fractional orbital phase) for hot-Jupiter exoplanets at visible wavelengths as a function of dayside cloud distribution with a uniformly averaged thermal profile. The models presented in this work can be adapted for a variety of planetary cases at visible wavelengths to include variations in planet–star separation, gravity, metallicity, and source-observer geometry. Finally, we tailor our model for comparison with, and confirmation of, the recent optical phase-curve observations of Kepler-7b with the Kepler space telescope. The average planetary albedo can vary between 0.1 and 0.6 for the 1300 cloud scenarios that were compared to the observations. Many of these cases cannot produce a high enough albedo to match the observations. We observe that smaller particle size and increasing cloud altitude have a strong effect on increasing albedo. In particular, we show that a set of models where Kepler-7b has roughly half of its dayside covered in small-particle clouds high in the atmosphere, made of bright minerals like MgSiO[subscript 3] and Mg[subscript 2]SiO[subscript 4], provide the best fits to the observed offset and magnitude of the phase-curve, whereas Fe clouds are found to be too dark to fit the observations

Incidence of Non-Hodgkin\u27s Lymphoma by Residential Proximity to Superfund Sites in Kentucky: A Multivariate Analysis

Non-Hodgkin’s Lymphoma (NHL) is a category of cancers that arise from the lymphocytes of the immune system. The rates of NHL in the United States and Kentucky began to rise in the mid-20th Century, shortly after the manufacture, use, and disposal of numerous chemical substances began to increase during and after the Second World War. While the etiology of NHL is not fully known, there are several chemical substances for which evidence exists of a possible link between exposures and development of NHL and other cancers. Several of these substances are also present in sites within Kentucky designated by the US Environmental Protection Agency as hazardous waste sites under the Superfund program. The present investigation sought to determine whether residential proximity to Superfund sites in Kentucky was a significant risk factor for NHL. Geospatial coordinates for all Superfund sites in Kentucky were obtained, along with US Census 2010 population data at the census tract level, and de-identified data from the Kentucky Cancer Registry for all NHL cases between 1995 and 2012, including residential geospatial coordinates. Incidence data was calculated at the level of census tract, except for \u3c5km buffer rings and 5-10km buffer circles around each Superfund site, whose NHL incidence data was calculated separately. Residence within the \u3c5km and 5-10km buffer zones were the exposure variables, and other potentially relevant covariates were considered for the models, and tested for multicollinearity and significance. Because of spatial autocorrelation of NHL incidence data and nonstationarity uncovered during exploratory regression and diagnostics, geographically weighted regression was used in addition to ordinary least squares regression. Using the best-fitting models, it was determined that residence less than 5km and between 5-10km from the nearest Superfund site were both significant factors in elevated cumulative NHL incidence rates. The Beale Code for rural/urban characteristics of the census tract was another significant predictor, with more rural areas having higher NHL incidence rates. Directions for future research, public health implications, and potential strategies for distal and proximal interventions are presented based on the results of this study