328 research outputs found
Building a Better mSUGRA: WIMP Dark Matter Without Flavor Violation
The appearance of a natural dark matter candidate, the neutralino, is among
the principal successes of minimal supergravity (mSUGRA) and its descendents.
In lieu of a suitable ultraviolet completion, however, theories of
gravity-mediated supersymmetry breaking such as mSUGRA suffer from arbitrary
degrees of flavor violation. Though theories of gauge-mediated supersymmetry
breaking are free from such prohibitive flavor violation, they typically lack
natural neutralino dark matter candidates. Yet this conventional dichotomy
breaks down when the hidden sector is strongly coupled; in models of
gauge-mediated supersymmetry breaking, the neutralino may be the lightest
supersymmetric particle (LSP) if the fields of the hidden sector possess large
anomalous dimensions. In fact, general models of so-called "sequestered" gauge
mediation possess the full richness of neutralino dark matter found in mSUGRA
without corresponding flavor problems. Here we explore generalized models of
sequestered gauge mediation and the rich variety of neutralino dark matter they
exhibit.Comment: 26 pages, 7 figure
Sequestering the Gravitino: Neutralino Dark Matter in Gauge Mediation
In conventional models of gauge-mediated supersymmetry breaking, the lightest
supersymmetric particle (LSP) is invariably the gravitino. However, if the
supersymmetry breaking sector is strongly coupled, conformal sequestering may
raise the mass of the gravitino relative to the remaining soft
supersymmetry-breaking masses. In this letter, we demonstrate that such
conformal dynamics in gauge-mediated theories may give rise to satisfactory
neutralino dark matter while simultaneously solving the flavor and mu/ B mu
problems.Comment: 16 pages, 3 figures. References added, discussion of A-terms amended,
figures revise
LHC Charge Asymmetry as Constraint on Models for the Tevatron Top Anomaly
The forward-backward asymmetry in top quark production at
the Tevatron has been observed to be anomalously large by both CDF and D0. It
has been suggested that a model with a coupling to and might
explain this anomaly, and other anomalies in mesons. Single-top-quark
production in this model is large, and arguably in conflict with Tevatron
measurements. However the model might still be viable if is
somewhat smaller than its current measured central value. We show that even
with smaller couplings, the model can be discovered (or strongly excluded) at
the LHC using the 2010 data sets. We find that a suitable charge-asymmetry
measurement is a powerful tool that can be used to constrain this and other
sources of anomalous single-top production, and perhaps other new high-energy
charge-asymmetric processes.Comment: 25 pages, 4 figures, note adde
Reheating Metastable O'Raifeartaigh Models
In theories with multiple vacua, reheating to a temperature greater than the
height of a barrier can stimulate transitions from a desirable metastable
vacuum to a lower energy state. We discuss the constraints this places on
various theories and demonstrate that in a class of supersymmetric models this
transition does not occur even for arbitrarily high reheating temperature.Comment: 21 pages, 1 figure. Typos corrected and some references adde
Small Intestinal Cannabinoid Receptor Changes Following a Single Colonic Insult with Oil of Mustard in Mice
Cannabinoids are known to be clinically beneficial for control of appetite disorders and nausea/vomiting, with emerging data that they can impact other GI disorders, such as inflammation. Post-inflammatory irritable bowel syndrome (PI-IBS) is a condition of perturbed intestinal function that occurs subsequent to earlier periods of intestinal inflammation. Cannabinoid 1 receptor (CB1R) and CB2R alterations in GI inflammation have been demonstrated in both animal models and clinically, but their continuing role in the post-inflammatory period has only been implicated to date. Therefore, to provide direct evidence for CBR involvement in altered GI functions in the absence of overt inflammation, we used a model of enhanced upper GI transit that persists for up to 4 weeks after a single insult by intracolonic 0.5% oil of mustard (OM) in mice. In mice administered OM, CB1R immunostaining in the myenteric plexus was reduced at day 7, when colonic inflammation is subsiding, and then increased at 28 days, compared to tissue from age-matched vehicle-treated mice. In the lamina propria CB2R immunostaining density was also increased at day 28. In mice tested 28 day after OM, either a CB1R-selective agonist, ACEA (1 and 3 mg/kg, s.c.) or a CB2R-selective agonist, JWH-133 (3 and 10 mg/kg, s.c.) reduced the enhanced small intestinal transit in a dose-related manner. Doses of ACEA and JWH-133 (1 mg/kg), alone or combined, reduced small intestinal transit of OM-treated mice to a greater extent than control mice. Thus, in this post-colonic inflammation model, both CBR subtypes are up-regulated and there is increased efficacy of both CB1R and CB2R agonists. We conclude that CBR remodeling occurs not only during GI inflammation but continues during the recovery phase. Thus, either CB1R- or CB2-selective agonists could be efficacious for modulating GI motility in individuals experiencing diarrhea-predominant PI-IBS
Finite Difference Room Acoustics Simulation with General Impedance Boundaries and Viscothermal Losses in Air: Parallel Implementation on Multiple GPUs
Rapid Evolutionary Rates and Unique Genomic Signatures Discovered in the First Reference Genome for the Southern Ocean Salp, Salpa thompsoni (Urochordata, Thaliacea)
A preliminary genome sequence has been assembled for the Southern Ocean salp, Salpa thompsoni (Urochordata, Thaliacea). Despite the ecological importance of this species in Antarctic pelagic food webs and its potential role as an indicator of changing Southern Ocean ecosystems in response to climate change, no genomic resources are available for S. thompsoni or any closely related urochordate species. Using a multiple-platform, multiple-individual approach, we have produced a 318,767,936-bp genome sequence, covering \u3e50% of the estimated 602 Mb (±173 Mb) genome size for S. thompsoni. Using a nonredundant set of predicted proteins, \u3e50% (16,823) of sequences showed significant homology to known proteins and ∼38% (12,151) of the total protein predictions were associated with Gene Ontology functional information. We have generated 109,958 SNP variant and 9,782 indel predictions for this species, serving as a resource for future phylogenomic and population genetic studies. Comparing the salp genome to available assemblies for four other urochordates, Botryllus schlosseri, Ciona intestinalis, Ciona savignyi and Oikopleura dioica, we found that S. thompsoni shares the previously estimated rapid rates of evolution for these species. High mutation rates are thus independent of genome size, suggesting that rates of evolution \u3e1.5 times that observed for vertebrates are a broad taxonomic characteristic of urochordates. Tests for positive selection implemented in PAML revealed a small number of genes with sites undergoing rapid evolution, including genes involved in ribosome biogenesis and metabolic and immune process that may be reflective of both adaptation to polar, planktonic environments as well as the complex life history of the salps. Finally, we performed an initial survey of small RNAs, revealing the presence of known, conserved miRNAs, as well as novel miRNA genes; unique piRNAs; and mature miRNA signatures for varying developmental stages. Collectively, these resources provide a genomic foundation supporting S. thompsoni as a model species for further examination of the exceptional rates and patterns of genomic evolution shown by urochordates. Additionally, genomic data will allow for the development of molecular indicators of key life history events and processes and afford new understandings and predictions of impacts of climate change on this key species of Antarctic pelagic ecosystems
Mapping the Association of Global Executive Functioning Onto Diverse Measures of Psychopathic Traits
Psychopathic individuals display a callous-coldhearted approach to interpersonal and affective situations and engage in impulsive and antisocial behaviors. Despite early conceptualizations suggesting that psychopathy is related to enhanced cognitive functioning, research examining executive functioning (EF) in psychopathy has yielded few such findings. It is possible that some psychopathic trait dimensions are more related to EF than others. Research using a 2-factor or 4-facet model of psychopathy highlights some dimension-specific differences in EF, but this research is limited in scope. Another complicating factor in teasing apart the EF–psychopathy relationship is the tendency to use different psychopathy assessments for incarcerated versus community samples. In this study, an EF battery and multiple measures of psychopathic dimensions were administered to a sample of male prisoners (N
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