7,494 research outputs found
Energy Positivity, Non-Renormalization, and Holomorphy in Lorentz-Violating Supersymmetric Theories
This paper shows that the positive-energy and non-renormalization theorems of
traditional supersymmetry survive the addition of Lorentz violating
interactions. The Lorentz-violating coupling constants in theories using the
construction of Berger and Kostelecky must obey certain constraints in order to
preserve the positive energy theorem. Seiberg's holomorphic arguments are used
to prove that the superpotential remains non-renormalized (perturbatively) in
the presence of Lorentz-violating interactions of the Berger-Kostelecky type.
We briefly comment on Lorentz-violating theories of the type constructed by
Nibbelink and Pospelov to note that holomorphy arguments offer elegant proofs
of many non-renormalization results, some known by other arguments, some new.Comment: v3: Discussion and clarification added. References added. Results on
gauge-kinetic function expande
Trust on the Internet: A Virtual Reality?
Social capital has recently gained popularity, but it is not a new topic. The relationship between civic engagement and trust has been well tested, and it has been used in the past to help diagnose the well being of a society. Unfortunately with evolving technology, some of this research may be now obsolete. The internet has changed the way that people communicate and learn. Since the internet has reached such high proliferation rates, especially among the younger generations, it is likely to have an effect on the relationship between civic engagement and trust. Usin
PMMA Mechanical Test for the Medium Scale High Voltage Apparatus (MSHV)
This experiment at Oak Ridge National Laboratory (ORNL) aims to search for the electric dipole moment of the neutron (nEDM) at the 10^-28 level. One of the variables proportional to the sensitivity of the measurement is the strength of the electric field. The electrodes that generate the field will be made of polymethyl methacrylate (PMMA) and coated with a conductive material. This unique condition is further complicated by the fact that the system will be cooled to a temperature of 0.4 K. These conditions have not been attempted in the past and provide new challenges. In order to test solutions to these challenges, the MSHV was constructed. This apparatus allows potential coatings to be tested at 0.4 K to ensure that the electrodes for the final design will function as required. Due to stresses from thermal contraction occurring during cool down, components to transition from the PMMA electrodes to the existing support structure had to be selected to minimize the stress on each material. A mechanical test of this structure was performed at Los Alamos National Laboratory (LANL) to ensure that there are no failures of either structure or electrode. The results of this mechanical test, as well as the design and materials selected, will be discussed
The role of vitamin A during bio-mineral tissue development in pigs
PhD ThesisSkeletal health is a critical determinant of animal health and welfare. Kyphosis is one such
idiopathic skeletal disease that compromises the welfare of commercial pigs. Vitamin A
regulates the expression of genes that define bone growth and development, and has been
suggested to associate with kyphosis. This thesis aimed to establish the molecular basis of
kyphosis, clarify vitamin A’s role on the expression of genes that regulate skeletal
development, and to ascertain vitamin A’s role on gene expression in kyphotic pigs.
The TGF-β signalling pathway was associated with kyphotic bone and cartilage tissues. This
was due to bone and cartilage tissues showing associations with small-leucine rich
proteoglycans, ASPN and DCN respectively, which regulate TGF- β signalling. Potential
effects as a result of differential gene expression include reduced endochondral bone
growth and deterioration of articular cartilage.
The dose of vitamin A was observed to be a critical factor in the regulation of expression of
skeletal genes within bone tissue. Genes related to the family of Rho-GTPases, which control
cytoskeletal dynamics, were observed to be differentially regulated within the trabecular
bone in response to vitamin A. In addition, vitamin A dose was observed to initially
antagonise serum 25(OH) D, and upon full saturation of the liver with vitamin A, serum
25(OH) D was restored through, as of yet, unknown mechanisms.
The gene GIT2, which associates with Rho-GTPases, was observed to be differentially
downregulated within kyphotic trabecular bone, and showed a dose-response relationship
with vitamin A supplementation. Furthermore, kyphotic pigs were indicated to have
reduced vitamin D status.
This research has outlined the molecular basis of kyphosis in pigs, and has indicated vitamin
A and vitamin D drive the disease. The research also outlines the role of how excessive
vitamin A controls the expression of genes that regulate bio-mineralisation in trabecular
bone. The thesis has also offered novel insights into vitamin A’s potential role in regulating
gene expression during kyphotic development
The Efficacy of Mindfulness Based Interventions for Soldiers and Veterans
The psychological impacts of war can be devastating for soldiers and veterans. Even for those who have not seen combat, military service can be a stressful experience. Although posttraumatic stress disorder (PTSD) has been identified as the most common form of psychopathology in this population, military personnel are susceptible to a variety of other mental illnesses, including anxiety, depression, and substance use disorders (Prigerson, Maciejewski, & Rosenheck, 2002). Meta-analytic reviews demonstrate the efficacy of exposure-based interventions for soldiers and veterans with symptoms of posttraumatic stress (PTS), but results are inconclusive regarding the efficacy of other treatments for military servicemembers (Kitchiner, Roberts, Wilcox, & Bisson, 2012). Further, there appears to be a significant portion of soldiers and veterans with PTSD that does not respond to exposure-based treatments (Sher & Yehuda, 2011). Mindfulness-based interventions have shown to be effective in treating a breadth of psychopathology in civilian populations (Khoury et al., 2013). The purpose of the proposed study was to conduct a meta-analysis analyzing the efficacy of such interventions, specifically with soldiers and veterans. Three major literature databases, PsycINFO, Medline, and Cochrane were searched for randomized controlled studies that used mindfulness-based interventions with soldiers and veterans. It was hypothesized that mindfulness-based interventions would be shown to be efficacious for soldiers and veterans. Format and dosage of treatment, study quality, and diagnosis were coded and examined as potential moderator variables. General support was found for the efficacy of mindfulness-based interventions with soldiers in terms of reduction of symptoms of PTS and depression and positive changes in various “other” outcome areas. Future meta-analyses on this topic would benefit from incorporating biological and physical health outcome data (which were excluded from the present study)
Neutral Pion Background Analysis at STAR
The STAR detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory takes measurements of cross section and spin observables of polarized proton collisions. The Endcap Electromagnetic Calorimeter (EEMC) allows measurements of electromagnetic particles in the forward direction, 1 \u3c η \u3c 2. The EEMC detector will be used to measure the neutral pion (π0) double longitudinal spin asymmetry which gives us information about the gluon contribution to the proton\u27s spin. The π0 cross section is an important measurement to verify our signal reconstruction and the background characterization. In order to measure the π0 cross section and asymmetry, the backgrounds must be identified (such as those from photon conversions and reconstruction errors where one photon reconstructs as two clusters). This project describes efforts toward measuring the π0 cross section and asymmetry, specifically efforts to understand π0 background using Monte Carlo computer simulation events and collision data
Quantifying Glacier-Derived Summer Runoff in Northwest Montana
Glacier National Park, located in northwest Montana contains the second largest concentration of glaciers in the U.S. Rocky Mountains. However, total glacier-covered area has shrunk by almost 30% over the past 50 years. This has important implications for local glacier-fed streams, especially during the typically hot and dry summer month of August. This study is the first attempt to quantify the volume of glacier meltwater entering local streams. We simulate glacier-melt generation during the summers of 2009 and 2010 using a modified temperature-index model that includes solar radiation as input. The model was calibrated with data from weather stations installed on five different glaciers and in situ measurements of surface ablation. Simulated glacier-melt hereafter glacier runoff from within gauged basins was then compared to measured stream discharge for the month of August to assess the relative contribution of glacier runoff to stream flows. We find the fraction of August stream discharge potentially derived from glaciers is not linearly proportionate to glacier cover. In watersheds only 0.12% glacierized, glacier runoff equals 5%-6% of the August total discharge; glacier runoff is 23%-28% of the discharge in a stream draining a basin 1.4% glacierized; and, in the small alpine catchments where glacier cover exceeds 25% of the basin area, glacier runoff likely accounts for almost all of the total runoff. Our work suggests that during dry summer months, glacier runoff is a primary control on both water availability and water temperature in small alpine basins with a catchment area on the order of tens of km2 and smaller and that are located within 20 km of the continental divide. However, the significance of meltwater diminishes quickly when travelling downstream and that in larger rivers situated 50 km or more from glaciers, glacier runoff is minimally important
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