2,361 research outputs found
Stops and MET: the shape of things to come
LHC experiments have placed strong bounds on the production of supersymmetric
colored particles (squarks and gluinos), under the assumption that all flavors
of squarks are nearly degenerate. However, the current experimental constraints
on stop squarks are much weaker, due to the smaller production cross section
and difficult backgrounds. While light stops are motivated by naturalness
arguments, it has been suggested that such particles become nearly impossible
to detect near the limit where their mass is degenerate with the sum of the
masses of their decay products. We show that this is not the case, and that
searches based on missing transverse energy (MET) have significant reach for
stop masses above 175 GeV, even in the degenerate limit. We consider direct
pair production of stops, decaying to invisible LSPs and tops with either
hadronic or semi-leptonic final states. Modest intrinsic differences in MET are
magnified by boosted kinematics and by shape analyses of MET or suitably-chosen
observables related to MET. For these observables we show that the
distributions of the relevant backgrounds and signals are well-described by
simple analytic functions, in the kinematic regime where signal is enhanced.
Shape analyses of MET-related distributions will allow the LHC experiments to
place significantly improved bounds on stop squarks, even in scenarios where
the stop-LSP mass difference is degenerate with the top mass. Assuming 20/fb of
luminosity at 8 TeV, we conservatively estimate that experiments can exclude or
discover degenerate stops with mass as large as ~ 360 GeV and 560 GeV for
massless LSPs.Comment: Version submitted to journal with improved analysis and small fixes,
27 pages, 11 figures, 2 table
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Depressive symptoms are associated with visceral adiposity in a community-based sample of middle-aged women and men
To examine the relation between measures of adiposity and depressive symptoms in a large well characterized community-based sample, we examined the relations of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) to depressive symptoms in 1581 women (mean age 52.2 years) and 1718 men (mean age 49.8 years) in the Framingham Heart Study. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression (CES-D) scale. Regression models were created to examine the association between each fat depot (exposure) and depressive symptoms (outcome). Sex specific models were adjusted for age, body mass index, smoking, alcohol consumption, diabetes, hypertension, total and HDL cholesterol, lipid lowering treatment, CVD, menopause, C-reactive protein, and physical activity. Mean CES-D scores were 6.8 and 5.6 in women and men. High levels of depressive symptoms were present in 22.5% of women and 12.3% of men. In women, one standard deviation increase in VAT was associated with a 1.3 point higher CES-D score after adjusting for age and BMI (p<0.01) and remained significant in the fully adjusted model (p=0.03). The odds ratio of depressive symptoms per 1 standard deviation increase in VAT in women was 1.33 (p=0.015); results were attenuated in fully adjusted models (OR 1.29, p=0.055). In men, the association between VAT and CES-D score and depressive symptoms was not significant. SAT was not associated with CES-D score or depressive symptoms. This study supports an association between VAT and depressive symptoms in women. Further work is needed to uncover the complex biologic mechanisms mediating the association
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Prevalence, Distribution, and Risk Factor Correlates of High Thoracic Periaortic Fat in the Framingham Heart Study
Background: Thoracic periaortic adipose tissue (TAT) is associated with atherosclerosis and cardiovascular disease (CVD) risk factors and may play a role in obesity‐mediated vascular disease. We sought to determine the prevalence, distribution, and risk factor correlates of high TAT. Methods and Results: Participants from the Framingham Heart Study (n=3246, 48% women, mean age 51.1 years) underwent multidetector computed tomography; high TAT and visceral adipose tissue (VAT) were defined on the basis of sex‐specific 90th percentiles in a healthy referent sample. The prevalence of high TAT was 38.1% in women and 35.7% in men. Among individuals without high VAT, 10.1% had high TAT. After adjustment for age and VAT, both women and men with high TAT in the absence of high VAT were older and had a higher prevalence of CVD (P<0.0001) compared with those without high TAT. In addition, men in this group were more likely to be smokers (P=0.02), whereas women were more likely to have low high‐density lipoprotein cholesterol (P=0.005). Conclusions: Individuals in our community‐based sample with high TAT in the absence of high VAT were characterized by an adverse cardiometabolic profile. This adipose tissue phenotype may identify a subset of individuals with distinct metabolic characteristics
The Interaction of Photoactivators with Proteins during Microfabrication
Micron-scale protein cross-linking or microfabrication has been carried out using an Nd3+–YAG laser as the excitation source. Fabrication is carried out by the excitation of photoactivators (Rose Bengal, methylene blue and 9-fluorenone-2-carboxylic acid) with the ultimate goal of creating stable structures that will serve as models for various applications (drug delivery and tissue engineering). Experimental parameters have been adjusted to minimize photodamage and maximize cross-linking efficiency. The higher than ideal photon flux and peak power necessitates the use of high protein concentrations to minimize photodamage. Rose Bengal and methylene blue are binding to proteins with high association constants (Ka ≈ 106 M−1) and both Rose Bengal and both 9-fluorenone-2-carboxylic acid are showing changes to their excited states in presence of proteins at cross-linking concentrations. Molecular docking studies show that Rose Bengal binds close to the tryptophan with ΔG = −6.15 kcal/mol
A programme for risk assessment and minimisation of progressive multifocal leukoencephalopathy developed for vedolizumab clinical trials
Introduction Over the past decade, the potential for drug-associated progressive multifocal leukoencephalopathy (PML) has become an increasingly important consideration in certain drug development programmes, particularly those of immunomodulatory biologics. Whether the risk of PML with an investigational agent is proven (e.g. extrapolated from relevant experience, such as a class effect) or merely theoretical, the serious consequences of acquiring PML require careful risk minimisation and assessment. No single standard for such risk minimisation exists. Vedolizumab is a recently developed monoclonal antibody to α4β7 integrin. Its clinical development necessitated a dedicated PML risk minimisation assessment as part of a global preapproval regulatory requirement.
Objective The aim of this study was to describe the multiple risk minimisation elements that were incorporated in vedolizumab clinical trials in inflammatory bowel disease patients as part of the risk assessment and minimisation of PML programme for vedolizumab.
Methods A case evaluation algorithm was developed for sequential screening and diagnostic evaluation of subjects who met criteria that indicated a clinical suspicion of PML. An Independent Adjudication Committee provided an independent, unbiased opinion regarding the likelihood of PML.
Results Although no cases were detected, all suspected PML events were thoroughly reviewed and successfully adjudicated, making it unlikely that cases were missed.
Conclusion We suggest that this programme could serve as a model for pragmatic screening for PML during the clinical development of new drugs
Cliffbot Maestro
Cliffbot Maestro permits teleoperation of remote rovers for field testing in extreme environments. The application user interface provides two sets of tools for operations: stereo image browsing and command generation
Spatial Query for Planetary Data
Science investigators need to quickly and effectively assess past observations of specific locations on a planetary surface. This innovation involves a location-based search technology that was adapted and applied to planetary science data to support a spatial query capability for mission operations software. High-performance location-based searching requires the use of spatial data structures for database organization. Spatial data structures are designed to organize datasets based on their coordinates in a way that is optimized for location-based retrieval. The particular spatial data structure that was adapted for planetary data search is the R+ tree
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