1,636 research outputs found
Numerical Algorithms for finding Black Hole solutions of Einstein's Equations
Einstein's Theory of General Relativity has proven remarkably successful
at modelling a wide range of gravitational phenomena. Amongst
some of the novel features in this description is the existence of black
holes; regions of space-time where gravity is so strong that light cannot
escape. The properties of black holes have been extensively studied
within General Relativity, culminating in the result that the few known
space-times are the only allowed stationary black hole solutions in four
dimensions.
In the past half century, research has focused on how to unify the
distinct theories of gravity and quantum mechanics. A common theme
amongst several strong candidates is that space-time, the backdrop for
gravity, is fundamentally higher dimensional. In these theories, the
structure of black hole solutions is relatively unknown and expected to
be much richer; finding such solutions is, however, a very hard task.
In this thesis, we introduce new numerical methods to study higher
dimensional black holes. The methods, based on refinements of existing
work and the novel application of standard techniques, are then
used to study a number of black hole space-times. Namely the structure
of black holes on a Kaluza-Klein background, and rotating Kerr
black holes. We demonstrate that these algorithms can be applied in
a wide class of situations and yield good quality results with comparative
ease. New results are presented in both cases studied. We examine
the predicted merger between non-uniform black strings and localised
black holes on a Kaluza-Klein background. We find evidence for a new
type of non-uniform black string with one Euclidean negative mode
and lower entropy than the uniform strings. We discover a window of localised black holes with one Euclidean negative mode but positive
specific heat. We also look at the local structure of the merger point
and find consistency with Kol's cone prediction
Highly metastatic K7M2 cell line: A novel murine model capable of in vivo imaging via luciferase vector transfection
Osteosarcoma is rare and little improvement in survival rates has occurred in the last 25 years despite modern chemotherapeutic treatment. Bioluminescent cell lines for the modeling of osteosarcoma have shown success in tracking metastases in vivo, but commonly use adenoviral vectors to transfect the native cell line with bioluminescent reporters. The purpose of this study was to develop an orthotopic model for metastatic osteosarcoma capable of in vivo monitoring of metastatic and primary tumor burden in an immunocompetent mouse and compare that model to its wild type pathogenesis. K7M2 cells were transfected using a plasmid vector and were stable after 12 weeks. Thirty-four female BALB/c mice aged four to five weeks underwent orthotopic implantation of either wild type (n=12) or transfected (n=22) K7M2 cells in the proximal tibia. Mice were monitored for tumor growth and weekly In Vivo Imaging System (IVIS) imaging was performed to monitor for pulmonary metastasis. Although tumors developed sooner in the wild type group, no significant differences were seen compared to Transfected Group 1 in rate of inoculation, growth rates after first detection, metastatic rate, and time between inoculation and death. This study establishes a new murine model for metastatic osteosarcoma using the K7M2-wt cell line transfected with a non-viral plasmid luciferase vector. The benefits of this preclinical model include an intact immune system and orthotopically driven metastatic disease; this model appears comparable to its wild type counterpart. In the future, the model may be used to examine promising immunomodulatory therapies using bioluminescence in vivo
The Roth Project - Music and Memory: A Community Agency Initiated Individualized Music Intervention for People with Dementia
Introduction
“The Roth Project - Music and Memory” is a music based intervention program, implemented by the Alzheimer’s Association of Central and Western Kansas, which provides a nonpharmacologicalmeans for addressing neuropsychiatric symptoms in individuals with dementia.
Methods
Participants were individuals with dementia who were enrolled in The Roth Project - Music and Memory. Post-intervention surveys were distributed to caregivers of participants which assessed caregiver satisfaction with the program as well as caregiver perception of the impact of individualized music on mood and behavioralsymptoms.
Results
Of returned surveys (n = 79), 99% of caregivers indicated they were satisfied or very satisfied with the program and 94% of caregivers perceived participants to like or very much like listening to the music. While a substantial number of participants required assistance with iPod use (95%), the majority of participants were observed to listen to the music with stable or increased frequency over time. Personalized music was observed to improve mood in 78% of cases, with the most frequent benefits being improved overall happiness, decreased anxiety, increased positive emotional expression, and decreased depression.
Conclusions
The Roth Project - Music and Memory was well received by caregivers and was perceived to benefit mood of individuals with dementia. These results provided ongoing support for individualized music-based interventions and demonstrated that such interventions, when implemented by community agencies, can be well received by those who use them
Host-linked soil viral ecology along a permafrost thaw gradient
Climate change threatens to release abundant carbon that is sequestered at high latitudes, but the constraints on microbial metabolisms that mediate the release of methane and carbon dioxide are poorly understood1,2,3,4,5,6,7. The role of viruses, which are known to affect microbial dynamics, metabolism and biogeochemistry in the oceans8,9,10, remains largely unexplored in soil. Here, we aimed to investigate how viruses influence microbial ecology and carbon metabolism in peatland soils along a permafrost thaw gradient in Sweden. We recovered 1,907 viral populations (genomes and large genome fragments) from 197 bulk soil and size-fractionated metagenomes, 58% of which were detected in metatranscriptomes and presumed to be active. In silico predictions linked 35% of the viruses to microbial host populations, highlighting likely viral predators of key carbon-cycling microorganisms, including methanogens and methanotrophs. Lineage-specific virus/host ratios varied, suggesting that viral infection dynamics may differentially impact microbial responses to a changing climate. Virus-encoded glycoside hydrolases, including an endomannanase with confirmed functional activity, indicated that viruses influence complex carbon degradation and that viral abundances were significant predictors of methane dynamics. These findings suggest that viruses may impact ecosystem function in climate-critical, terrestrial habitats and identify multiple potential viral contributions to soil carbon cycling
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Summary report : direct approaches for recycling carbon dioxide into synthetic fuel.
The consumption of petroleum by the transportation sector in the United States is roughly equivalent to petroleum imports into the country, which have totaled over 12 million barrels a day every year since 2004. This reliance on foreign oil is a strategic vulnerability for the economy and national security. Further, the effect of unmitigated CO{sub 2} releases on the global climate is a growing concern both here and abroad. Independence from problematic oil producers can be achieved to a great degree through the utilization of non-conventional hydrocarbon resources such as coal, oil-shale and tarsands. However, tapping into and converting these resources into liquid fuels exacerbates green house gas (GHG) emissions as they are carbon rich, but hydrogen deficient. Revolutionary thinking about energy and fuels must be adopted. We must recognize that hydrocarbon fuels are ideal energy carriers, but not primary energy sources. The energy stored in a chemical fuel is released for utilization by oxidation. In the case of hydrogen fuel the chemical product is water; in the case of a hydrocarbon fuel, water and carbon dioxide are produced. The hydrogen economy envisions a cycle in which H{sub 2}O is re-energized by splitting water into H{sub 2} and O{sub 2}, by electrolysis for example. We envision a hydrocarbon analogy in which both carbon dioxide and water are re-energized through the application of a persistent energy source (e.g. solar or nuclear). This is of course essentially what the process of photosynthesis accomplishes, albeit with a relatively low sunlight-to-hydrocarbon efficiency. The goal of this project then was the creation of a direct and efficient process for the solar or nuclear driven thermochemical conversion of CO{sub 2} to CO (and O{sub 2}), one of the basic building blocks of synthetic fuels. This process would potentially provide the basis for an alternate hydrocarbon economy that is carbon neutral, provides a pathway to energy independence, and is compatible with much of the existing fuel infrastructure
Gene content evolution in the arthropods
Arthropods comprise the largest and most diverse phylum on Earth and play vital roles in nearly every ecosystem. Their diversity stems in part from variations on a conserved body plan, resulting from and recorded in adaptive changes in the genome. Dissection of the genomic record of sequence change enables broad questions regarding genome evolution to be addressed, even across hyper-diverse taxa within arthropods. Using 76 whole genome sequences representing 21 orders spanning more than 500 million years of arthropod evolution, we document changes in gene and protein domain content and provide temporal and phylogenetic context for interpreting these innovations. We identify many novel gene families that arose early in the evolution of arthropods and during the diversification of insects into modern orders. We reveal unexpected variation in patterns of DNA methylation across arthropods and examples of gene family and protein domain evolution coincident with the appearance of notable phenotypic and physiological adaptations such as flight, metamorphosis, sociality, and chemoperception. These analyses demonstrate how large-scale comparative genomics can provide broad new insights into the genotype to phenotype map and generate testable hypotheses about the evolution of animal diversity
Product Binding Enforces the Genomic Specificity of a Yeast Polycomb Repressive Complex
We characterize the Polycomb system that assembles repressive subtelomeric domains of H3K27 methylation (H3K27me) in the yeast Cryptococcus neoformans. Purification of this PRC2-like protein complex reveals orthologs of animal PRC2 components as well as a chromodomain-containing subunit, Ccc1, which recognizes H3K27me. Whereas removal of either the EZH or EED ortholog eliminates H3K27me, disruption of mark recognition by Ccc1 causes H3K27me to redistribute. Strikingly, the resulting pattern of H3K27me coincides with domains of heterochromatin marked by H3K9me. Indeed, additional removal of the C. neoformans H3K9 methyltransferase Clr4 results in loss of both H3K9me and the redistributed H3K27me marks. These findings indicate that the anchoring of a chromatin-modifying complex to its product suppresses its attraction to a different chromatin type, explaining how enzymes that act on histones, which often harbor product recognition modules, may deposit distinct chromatin domains despite sharing a highly abundant and largely identical substrate—the nucleosome
Product Binding Enforces the Genomic Specificity of a Yeast Polycomb Repressive Complex
We characterize the Polycomb system that assembles repressive subtelomeric domains of H3K27 methylation (H3K27me) in the yeast Cryptococcus neoformans. Purification of this PRC2-like protein complex reveals orthologs of animal PRC2 components as well as a chromodomain-containing subunit, Ccc1, which recognizes H3K27me. Whereas removal of either the EZH or EED ortholog eliminates H3K27me, disruption of mark recognition by Ccc1 causes H3K27me to redistribute. Strikingly, the resulting pattern of H3K27me coincides with domains of heterochromatin marked by H3K9me. Indeed, additional removal of the C. neoformans H3K9 methyltransferase Clr4 results in loss of both H3K9me and the redistributed H3K27me marks. These findings indicate that the anchoring of a chromatin-modifying complex to its product suppresses its attraction to a different chromatin type, explaining how enzymes that act on histones, which often harbor product recognition modules, may deposit distinct chromatin domains despite sharing a highly abundant and largely identical substrate—the nucleosome
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