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

Galactic Cosmic Rays from 1 MeV to 1 GeV as Measured by Voyager beyond the Heliopause

Voyager 1 has now been beyond the heliopause for over 5 years since its seminal crossing of this boundary in August of 2012. During its epic 40 year journey of ~122 AU out to this boundary and beyond this spacecraft has passed through several regions of the heliosphere including the heliosheath of extent ~30 AU just inside the heliopause (HP), where extremely large and variable intensities of protons, helium and oxygen nuclei as well as electrons between 1 and 100 MeV were observed. Then, suddenly these particles completely vanished and new and completely different spectra of particles between 1 MeV up to ~1 GeV and beyond, instantly recognizable as those for galactic cosmic rays were observed. These spectra and intensities at all energies have remained constant to within ±1% for 5 years corresponding to 20 AU beyond the HP

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

Optical monitoring of GRO phase 1 objects

A brief overview is given of the three phases of our Gamma Ray Observatory (GRO) optical monitoring program. The acquisition of simultaneous GRO/optical data on targeted Oriented Scintillation Spectrometer Experiment (OSSE) objects, the collection of noncoincident observations of suspected GRO gamma ray emitters to determine their level of activity, and the optical imaging of burst fields in an attempt to identify the burst source are discussed. Finally, a table of future simultaneous optical observations of Phase 1 GRO targets is presented along with plans for the rapid optical imaging of gamma ray burst fields

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