A Search for Relativistic Magnetic Monopoles with the IceCube 22-String Detector

Magnetic monopoles are particles which act as a source for divergent magnetic fields, equivalent to a proton's electric field. Beyond simply adding the final symmetry to Maxwell's equations, their existence would solve numerous outstanding problems in the particle physics community. However, no conclusive evidence for their existence has been found. Magnetic monopoles possess many unique characteristics that allow for detection from a variety of experimental methods. One property is the large scaling of the Cherenkov radiation (&#8764; 8300) compared to electrically charged particles. Magnetic monopoles are postulated to be extremely heavy (&#8764; 104&#8722;1017 GeV). However, they would be topologically stable and accelerated via magnetic field lines throughout the universe, potentially reaching energies &#8764; 1015 GeV. Therefore, searches for relativistic magnetic monopoles incident on Earth are an important piece to the overall experimental search. The IceCube neutrino observatory, located at the South Pole, offers a novel environment to search for these particles. IceCube is a km3</super grid of light sensors buried deep within the Antarctic Ice Shelf and represents the most colossal neutrino telescope in the world. The large instrumented volume and relatively clear glacial ice allows for a significant improvement in sensitivity to the bright tracks relativistic magnetic monopoles would exhibit. The main background comes from large muon bundles produced in air showers generated by the highest energy cosmic rays. The depth of the detector allows for a limited rejection of these events from the Southern Hemisphere, while the Earth acts as an opaque shield to these events traveling from the Northern Hemisphere. In contrast, a large range of potential magnetic monopole masses and energies considered (M & 107 GeV, E & 1011 GeV) can travel completely through the Earth while remaining relativistic. This dissertation details the first search performed for these relativistic magnetic monopoles with IceCube data. The data is from 2007, when IceCube operated as a partially completed detector with an instrumented volume of &#8764;0.2 km3. It considers monopoles at four discrete speeds: &#946; = 0.76, 0.8, 0.9, 0.995, ranging from just above the Cherenkov threshold in ice to a boost factor of 10. Discrimination between a potential magnetic monopole signal and background is achieved by considering the brightness and direction of the event. After an initial search revealed deficiencies in the simulated background model, a more conservative analysis produces limits that are &#8764; 10 x better than previous searches. The final limits are then transformed to be a limit on an isotropic flux at the Earth's surface, due to the dependence on direction to the overall sensitivity of the analysis

Optimization of NANOGrav's Time Allocation for Maximum Sensitivity to Single Sources

Pulsar Timing Arrays (PTAs) are a collection of precisely timed millisecond pulsars (MSPs) that can search for gravitational waves (GWs) in the nanohertz frequency range by observing characteristic signatures in the timing residuals. The sensitivity of a PTA depends on the direction of the propagating gravitational wave source, the timing accuracy of the pulsars, and the allocation of the available observing time. The goal of this paper is to determine the optimal time allocation strategy among the MSPs in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) for a single source of GW under a particular set of assumptions. We consider both an isotropic distribution of sources across the sky and a specific source in the Virgo cluster. This work improves on previous efforts by modeling the effect of intrinsic spin noise for each pulsar. We find that, in general, the array is optimized by maximizing time spent on the best-timed pulsars, with sensitivity improvements typically ranging from a factor of 1.5 to 4.Comment: Accepted by Astrophyiscal Journa

Vegetative Community Development over 30 Years within Mixed Pine-Hardwood Mine Reclamation sites in east Texas

The practice of mine reclamation aims to balance the energy needs of society with proactive environmental restoration of degraded land, and long-term studies of vegetative community development on reclaimed mine land have been invaluable in developing effective reclamation practices. This study investigated vegetative community characteristics (composition, richness, species importance)over a 30 year time frame in planted mixed pine-hardwood areas on reclaimed surface coal mine land in East Texas,United States. Reclaimed sites werecompared vegetatively to unmined reference forests. A chronological pattern wasshown for reclaimedcommunity developmentin both understory and overstorystrata. Understory community development exhibitednatural patterns, while theoverstory community varied with different groups of planted species. The olderreclaimed sites were most similar to unmined reference sites. Dissimilaritiesbetween mined and unmined communities were also apparent; for example, thewoody vine community of reference sites was much more substantial in midstoryand overstory strata as compared to reclaimed sites. Overall, this study providedbaseline ecological information about these plant communities that may assistland managers and researchers in furthering their development of reclamation techniques and attainment of reclamation goals

The Suggestibility of Older Witnesses

The present study compares younger and older adult witnesses’ susceptibility to misinformation. Previous research on the misinformation effect has not measured the relationship between the effect and individuals’ perceptions of their own memory abilities. Such perceptions, and general knowledge of one’s own memory processes, are referred to as “metamemory.” In order to examine the relationship between metamemory and the misinformation effect in the present study, participants also completed a questionnaire that assessed their perception of their memory functioning. Although older persons tend to perceive their memories as being faulty, the correlation between self-assessment of memory abilities and actual memory performance is relatively low (Zelinski, Gilewski, & Thompson, 1980). We therefore predicted that there would be a negligible relationship between participants’ self-assessed memory functioning and whether or not they were susceptible to misinformation, for both younger and older adults

87th Annual Georgia Public Health Association Meeting & Conference Report

The 87th Annual Meeting of the Georgia Public Health Association (GPHA) was held in Atlanta, Georgia, on March 22-23, 2016, with pre-conference (March 21st) and post-conference (March 23rd) Executive Board meetings. As Georgia’s leading forum for public health researchers, practitioners, and students, the annual meeting of the GPHA brings together participants from across the state to explore recent developments in the field and to exchange techniques, tools, and experiences. In recent years the venue for the GPHA annual conference has been Atlanta, with the 2017 GPHA Annual Meeting and Conference also scheduled to be held in Atlanta. Several new initiatives were highlighted as part of this year’s conference. These included three pre-conference workshops, expansion of academic sponsorships, an enhanced exhibit hall integrated with the poster sessions, silent auction, breaks and President’s Reception, an information booth, and an inaugural administration section track. The 2016 Annual Meeting & Conference added the Certified in Public Health (CPH) Continuing Education (CE) designation. The theme for the conference was Understanding Public Health: Research, Evidence and Practice, which reflects the science of public health

Development of GIS Maps for Southeast Florida Coral Reefs

The present report outlines the results of an integrated mapping project undertaken to provide a habitat map of the shallow Broward County seafloor between the 0m and 35m contour. The study area stretched from Golden Beach in northern Dade County to just north of the Palm Beach County line. To produce this map and assure its compatibility with other, in particular NOAA, mapping products, a series of data were integrated. Data types included Laser Airborne Depth Sounder (LADS) bathymetry, multi- and single-beam bathymetry, acoustic seafloor discrimination, ecological assessments, and groundtruthing. The method used for acoustic seafloor discrimination was based on the first echo and its associated tail, and on the second echo returns of a 200 kHz signal. Two survey systems were employed: QTC View and Echoplus. A series of controlled experiments and field verifications indicated that it was possible to distinguish acoustically between different scattering classes that correlated to different seafloor types. For the production of the final map, information obtained from LADS bathymetry, NOAA classification and scattering classes obtained by QTC View and Echoplus was fused. The final map showed three well-developed linear reef complexes, a series of deep and shallow ridges believed to be old shorelines, a large sand area between the middle and outer reefs, and a considerable amount of colonized pavement. Due to the lack of distinct geomorphologic zones, the maps were based solely on habitat as defined by the NOAA biogeography program; however distinctions between areas such as linear reef, spur and groove, and colonized pavement were based on benthic cover (as seen by acoustic seafloor discrimination and biological transects) and geomorphology. The outer linear reef was subdivided into four habitats: aggregated patch reef, spur and groove, linear reef and deep colonized pavement. The area east of the outer linear reef consisted of a very patchy environment with large patches of reef interspersed amongst the deep sand. These were more prevalent close to the reef and tapered off eastward, becoming sandier. The spur and groove, linear reef, and deep colonized pavement comprised the outer reef and were separated mainly based on geomorphology. The outer reef was separated from the middle linear reef by a wide sandy plane (deep sand), which was characterized overall by a different scattering class in QTC View than the shallow sand found inshore. Acoustic ground discrimination identified patches of higher scatter and lower scatter amongst the outer, middle, and inner linear reefs suggesting distinct benthic cover between these structures. The eastern boundary of the middle reef was distinct and easily mapped whereas acoustic discrimination aided in determining the western boundary. The inner reef was the least distinct reef as it is not a mature reef. Much of this reef is patchy growth atop an inshore ridge and reef zonation is absent. Acoustic ground discrimination suggested that patches of higher versus lower scatter existed between and within the linear reefs, indicating that dense fauna is patchily distributed. Shoreward of the inner reef, another sand area or a mixture of sand and colonized pavements were found. Several nearshore ridges were mapped that could be classified as linear reef habitat, but were thought to be of non-reefal origin. Therefore these structures were mapped separately even though similar habitat comprises the inshore ridges, the inner linear reef, and the shallow colonized pavements. Excluded habitats such as submerged vegetation and large rubble zones were not detected sufficiently enough to be mapped during this effort. Groundtruthing by way of underwater video drop cameras and in situ biological assessments aided in the refinement of the mapping categories. Accuracy assessment of an independent grid of target points showed the map to have a users accuracy between 83% and 97% and a producers accuracy between 81% and 95%. These are acceptable accuracies and compare similarly to NOAA published map accuracies. In conclusion, the amalgamation of several mapping approaches and data products provided a representative map of Broward County submarine habitats that was accurate to a very satisfactory level. The results of this survey are a good example of how similar mapping products can be attained through different means. The method employed to map Broward County appears to have equally and accurately illustrated the benthic community as more traditional methods like photo interpretation. Similar methodology should be used in other areas where photo interpretation is not feasible due to either absence of data or the turbidity of the water

Optimization of NANOGrav\u27s Time Allocation for Maximum Sensitivity to Single Sources

Pulsar timing arrays (PTAs) are a collection of precisely timed millisecond pulsars (MSPs) that can search for gravitational waves (GWs) in the nanohertz frequency range by observing characteristic signatures in the timing residuals. The sensitivity of a PTA depends on the direction of the propagating GW source, the timing accuracy of the pulsars, and the allocation of the available observing time. The goal of this paper is to determine the optimal time allocation strategy among the MSPs in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) for a single source of GW under a particular set of assumptions. We consider both an isotropic distribution of sources across the sky and a specific source in the Virgo cluster. This work improves on previous efforts by modeling the effect of intrinsic spin noise for each pulsar. We find that, in general, the array is optimized by maximizing time spent on the best-timed pulsars, with sensitivity improvements typically ranging from a factor of 1.5 to 4

Flashline Mars Arctic Research Station (FMARS) 2009 Crew Perspectives

A crew of six "astronauts" inhabited the Mars Society s Flashline Mars Arctic Research Station (FMARS) for the month of July 2009, conducting a simulated Mars exploration mission. In addition to the various technical achievements during the mission, the crew learned a vast amount about themselves and about human factors relevant to a future mission to Mars. Their experiences, detailed in their own words, show the passion of those with strong commitment to space exploration and detail the human experiences for space explorers including separation from loved ones, interpersonal conflict, dietary considerations, and the exhilaration of surmounting difficult challenges