Modeling the ionospheric response to the 28 October 2003 solar flare due to coupling with the thermosphere

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94973/1/rds5664.pd

On the Response of the Upper Atmosphere to Solar Flares.

Over the past several decades, modern civilizations have become increasingly dependent on spacecraft that reside in the near-Earth space environment. For this reason, scientists and engineers have been interested in understanding the causes of perturbations to the background state of the Earth’s upper atmosphere, and to quantify the impact of these events. As a result of the states of the thermosphere and ionosphere being directly dependent on the incident radiation from the sun, it is expected that sudden changes in the solar radiative output should cause significant changes in the upper atmosphere. Such dynamics are investigated in this study, specifically the manner in which solar flares affect the density, circulation, and temperature of the Earth’s thermosphere and ionosphere. A global model of this region is used to examine how the upper atmosphere responds to such transient events. In order to quantify the response, the model is run during realistic events in order to understand the magnitudes of the resulting perturbations to the global ionosphere-thermosphere system. In the thermosphere, density perturbations of approximately 15% are found to occur on the dayside within 1.5 hours after the start of a solar flare. The addition of solar energy to the dayside launches a traveling atmospheric disturbance which propagates towards the night-side at the local sound speed plus the background velocity. As the disturbance converges on itself near the midnight sector, density enhancements almost as large as those seen on the day-side can occur. Furthermore, these nightside neutral perturbations cause both enhancements and depletions in the night-side electron density.Ph.D.Space and Planetary PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/64623/1/dpawlows_1.pd

Prediction of preterm birth with and without preeclampsia using mid-pregnancy immune and growth-related molecular factors and maternal characteristics.

OBJECTIVE:To evaluate if mid-pregnancy immune and growth-related molecular factors predict preterm birth (PTB) with and without (±) preeclampsia. STUDY DESIGN:Included were 400 women with singleton deliveries in California in 2009-2010 (200 PTB and 200 term) divided into training and testing samples at a 2:1 ratio. Sixty-three markers were tested in 15-20 serum samples using multiplex technology. Linear discriminate analysis was used to create a discriminate function. Model performance was assessed using area under the receiver operating characteristic curve (AUC). RESULTS:Twenty-five serum biomarkers along with maternal age <34 years and poverty status identified >80% of women with PTB ± preeclampsia with best performance in women with preterm preeclampsia (AUC = 0.889, 95% confidence interval (0.822-0.959) training; 0.883 (0.804-0.963) testing). CONCLUSION:Together with maternal age and poverty status, mid-pregnancy immune and growth factors reliably identified most women who went on to have a PTB ± preeclampsia

Modeling the thermospheric response to solar flares

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95643/1/jgra19410.pd

Bacterial nitrate assimilation: gene distribution and regulation

In the context of the global nitrogen cycle, the importance of inorganic nitrate for the nutrition and growth of marine and freshwater autotrophic phytoplankton has long been recognized. In contrast, the utilization of nitrate by heterotrophic bacteria has historically received less attention because the primary role of these organisms has classically been considered to be the decomposition and mineralization of dissolved and particulate organic nitrogen. In the pre-genome sequence era, it was known that some, but not all, heterotrophic bacteria were capable of growth on nitrate as a sole nitrogen source. However, examination of currently available prokaryotic genome sequences suggests that assimilatory nitrate reductase (Nas) systems are widespread phylogenetically in bacterial and archaeal heterotrophs. Until now, regulation of nitrate assimilation has been mainly studied in cyanobacteria. In contrast, in heterotrophic bacterial strains, the study of nitrate assimilation regulation has been limited to Rhodobacter capsulatus, Klebsiella oxytoca, Azotobacter vinelandii and Bacillus subtilis. In Gram-negative bacteria, the nas genes are subjected to dual control: ammonia repression by the general nitrogen regulatory (Ntr) system and specific nitrate or nitrite induction. The Ntr system is widely distributed in bacteria, whereas the nitrate/nitrite-specific control is variable depending on the organism

Improving Livability in Doha: The Role of Neighborhood Microclimates, Land Use, and Materials in Rapidly Urbanizing Regions

Recent evidence suggests that some densely populated areas of the world will be uninhabitable in the coming century due to extreme climate events (e.g. heat waves, atmospheric pollution, and drought) and due to shifts in microclimate and breathable air, which are directly related to livability. With estimates that over 75% of the global population will be living in cities by mid-century, scholars, practitioners, and government officials are asking what cities can do to address the pressing social and environmental challenges that emerge from climate change. They are also seeking to learn how this knowledge may inform policy decisions regarding physical, social, and economic planning to ensure an inviting quality of life and livability in these future places. We believe that we have an unprecedented opportunity to use our knowledge, technology, and social capacities to reduce the likelihood of producing a catastrophic future. This study compares the livability of two seemingly unlikely locations - Doha, Qatar, a capital city on the Arabian Gulf, and Portland, Oregon, an important American city in the Pacific Northwest. These cities are growing at different rates, have diverse cultural histories and varied development patterns, yet are attempting to improve urban livability for citizens in each place and its surrounding region. Through an in-depth examination of the physical changes that have occurred in both places and their corresponding urban climate conditions, especially thermal comfort, we describe the similarities and differences that help to define the challenges facing the management of each. We look specifically at two important empirically-derived measurements of livability: air quality and urban heat island effect. By focusing on these environmental stressors in each place, we are able to evaluate the extent to which different growth and policy drivers have impacted the ability for people to enjoy a desirable quality of life in both cities - different, but appropriate to each. We include as part of our approach a conceptual framework, which describes the coupling of environmental and human conditions for which changes in development patterns have direct implications on the livability of each location. As a result of our analysis, we offer insights about actions that show promise of managing future livability in each city and focus primarily on the ability to manipulate selected aspects of urban form - those characteristics of massing, surface materials, and tree cover that can change the air pollution and urban heat stress experience in each place. We focus specifically on landscape and site scale modifications that show promise of improving air quality and/or reducing urban heat as a stressor. Since cities around the world are looking to nature to provide benefits to city inhabitants, we emphasize the salutary role of green infrastructure. While much is still to be discovered regarding the capacity for cities and their managers to adapt to the emerging challenges of climate change, population growth, and conventional development patterns, yet without sustained and promising actions, the cities that are home to the majority of people today may likely become either obsolete in the coming centuries or present less than desirable living conditions for their future residents. We recognize that while all cities are unique reflections of their unique biophysical, microclimatic, social, cultural, and natural contexts, they also share many similar circumstances and conditions - the identification of which may help policy makers address climate change more effectively. Our conclusions also support the fact that seemingly diverse cities do, in fact, contain similarities in terms of the local, environmental, and urban design conditions that determine air quality and contribute to urban heat island effect.qscienc

Population-Sequencing as a Biomarker of Burkholderia mallei and Burkholderia pseudomallei Evolution through Microbial Forensic Analysis

Large-scale genomics projects are identifying biomarkers to detect human disease. B. pseudomallei and B. mallei are two closely related select agents that cause melioidosis and glanders. Accurate characterization of metagenomic samples is dependent on accurate measurements of genetic variation between isolates with resolution down to strain level. Often single biomarker sensitivity is augmented by use of multiple or panels of biomarkers. In parallel with single biomarker validation, advances in DNA sequencing enable analysis of entire genomes in a single run: population-sequencing. Potentially, direct sequencing could be used to analyze an entire genome to serve as the biomarker for genome identification. However, genome variation and population diversity complicate use of direct sequencing, as well as differences caused by sample preparation protocols including sequencing artifacts and mistakes. As part of a Department of Homeland Security program in bacterial forensics, we examined how to implement whole genome sequencing (WGS) analysis as a judicially defensible forensic method for attributing microbial sample relatedness; and also to determine the strengths and limitations of whole genome sequence analysis in a forensics context. Herein, we demonstrate use of sequencing to provide genetic characterization of populations: direct sequencing of populations

A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy

Dwarf satellite galaxies are thought to be the remnants of the population of primordial structures that coalesced to form giant galaxies like the Milky Way. An early analysis noted that dwarf galaxies may not be isotropically distributed around our Galaxy, as several are correlated with streams of HI emission, and possibly form co-planar groups. These suspicions are supported by recent analyses, and it has been claimed that the apparently planar distribution of satellites is not predicted within standard cosmology, and cannot simply represent a memory of past coherent accretion. However, other studies dispute this conclusion. Here we report the existence (99.998% significance) of a planar sub-group of satellites in the Andromeda galaxy, comprising approximately 50% of the population. The structure is vast: at least 400 kpc in diameter, but also extremely thin, with a perpendicular scatter <14.1 kpc (99% confidence). Radial velocity measurements reveal that the satellites in this structure have the same sense of rotation about their host. This finding shows conclusively that substantial numbers of dwarf satellite galaxies share the same dynamical orbital properties and direction of angular momentum, a new insight for our understanding of the origin of these most dark matter dominated of galaxies. Intriguingly, the plane we identify is approximately aligned with the pole of the Milky Way's disk and is co-planar with the Milky Way to Andromeda position vector. The existence of such extensive coherent kinematic structures within the halos of massive galaxies is a fact that must be explained within the framework of galaxy formation and cosmology.Comment: Published in the 3rd Jan 2013 issue of Nature. 19 pages, 4 figures, 1 three-dimensional interactive figure. To view and manipulate the 3-D figure, an Adobe Reader browser plug-in is required; alternatively save to disk and view with Adobe Reade

Mutations in protocadherin 15 and cadherin 23 affect tip links and mechanotransduction in mammalian sensory hair cells

Immunocytochemical studies have shown that protocadherin-15 (PCDH15) and cadherin-23 (CDH23) are associated with tip links, structures thought to gate the mechanotransducer channels of hair cells in the sensory epithelia of the inner ear. The present report describes functional and structural analyses of hair cells from Pcdh15av3J (av3J), Pcdh15av6J (av6J) and Cdh23v2J (v2J) mice. The av3J and v2J mice carry point mutations that are predicted to introduce premature stop codons in the transcripts for Pcdh15 and Cdh23, respectively, and av6J mice have an in-frame deletion predicted to remove most of the 9th cadherin ectodomain from PCDH15. Severe disruption of hair-bundle morphology is observed throughout the early-postnatal cochlea in av3J/av3J and v2J/v2J mice. In contrast, only mild-to-moderate bundle disruption is evident in the av6J/av6J mice. Hair cells from av3J/av3J mice are unaffected by aminoglycosides and fail to load with [3H]-gentamicin or FM1-43, compounds that permeate the hair cell's mechanotransducer channels. In contrast, hair cells from av6J/av6J mice load with both FM1-43 and [3H]-gentamicin, and are aminoglycoside sensitive. Transducer currents can be recorded from hair cells of all three mutants but are reduced in amplitude in all mutants and have abnormal directional sensitivity in the av3J/av3J and v2J/v2J mutants. Scanning electron microscopy of early postnatal cochlear hair cells reveals tip-link like links in av6J/av6J mice, substantially reduced numbers of links in the av3J/av3J mice and virtually none in the v2J/v2J mice. Analysis of mature vestibular hair bundles reveals an absence of tip links in the av3J/av3J and v2J/v2J mice and a reduction in av6J/av6J mice. These results therefore provide genetic evidence consistent with PCDH15 and CDH23 being part of the tip-link complex and necessary for normal mechanotransduction

A characteristics framework for Semantic Information Systems Standards

Semantic Information Systems (IS) Standards play a critical role in the development of the networked economy. While their importance is undoubted by all stakeholders—such as businesses, policy makers, researchers, developers—the current state of research leaves a number of questions unaddressed. Terminological confusion exists around the notions of “business semantics”, “business-to-business interoperability”, and “interoperability standards” amongst others. And, moreover, a comprehensive understanding about the characteristics of Semantic IS Standards is missing. The paper addresses this gap in literature by developing a characteristics framework for Semantic IS Standards. Two case studies are used to check the applicability of the framework in a “real-life” context. The framework lays the foundation for future research in an important field of the IS discipline and supports practitioners in their efforts to analyze, compare, and evaluate Semantic IS Standard