1,398 research outputs found
Searching for Confining Hidden Valleys at the LHC(b)
We explore strategies for probing Hidden Valley scenarios exhibiting
confinement. Such scenarios lead to a multiplicity of light hidden hadrons from
showering processes. Their decays are typically soft and displaced, making them
challenging to probe with traditional LHC searches. We show the low trigger
thresholds and excellent track and vertex reconstruction at LHCb provide an
ideal environment to search for such signals -- in both muonic and hadronic
channels. We also explore the potential of ATLAS/CMS and discuss modifications
to present searches that might make these experiments competitive with the LHCb
reach. Our proposed searches can probe models with dominant decays
to dark sectors as well as exotic Higgs boson decays in Twin Higgs models.Comment: 6 pages, 3 figure
A Comparison of Water Potential and Mechanical Strength of Tip and Base Leaves in Heteromeles arbutifolia
Heteromeles arbutifolia, commonly known as, Hollywood, is a plant that is extremely common in the California Chaparral ecosystem. It was observed that with Hollywood, the leaves grow on the tips of the branches predominantly. However, there are leaves that grow on the base of the branches that appear to be equally as healthy. The purpose of this investigation was to determine whether the leaves that grow at the tips of the branches or at the base of the branches were better suited to benefit the rest of the plant. Our hypothesis was that the leaves at the tips of the branches would be better suited to benefit the rest of the plant due to their better access to sunlight, as the rest of the plant does not overshadow them. We determined which leaves would be better suited to benefit the plant by measuring the water potential and mechanical strength of leaves at the tip and bases of branches on Heteromeles arbutifolia plants across the street from the Pepperdine cross. Samples were collected from Heteromeles arbutifolia specimens that were both in the sun and in the shade. After the results were compared, the plants in the sun showed that leaves at the base were mechanically stronger than those at the tip, while plants in the shade showed leaves at the tip were mechanically stronger. As for water potential, base leaves had higher water potential across the board
Markov-Switching Model Selection Using Kullback-Leibler Divergence
In Markov-switching regression models, we use Kullback-Leibler (KL) divergence between the true and candidate models to select the number of states and variables simultaneously. In applying Akaike information criterion (AIC), which is an estimate of KL divergence, we find that AIC retains too many states and variables in the model. Hence, we derive a new information criterion, Markov switching criterion (MSC), which yields a marked improvement in state determination and variable selection because it imposes an appropriate penalty to mitigate the over-retention of states in the Markov chain. MSC performs well in Monte Carlo studies with single and multiple states, small and large samples, and low and high noise. Furthermore, it not only applies to Markov-switching regression models, but also performs well in Markov- switching autoregression models. Finally, the usefulness of MSC is illustrated via applications to the U.S. business cycle and the effectiveness of media advertising.Research Methods/ Statistical Methods,
Linguistics
Contains table of contents, an introduction and abstracts for two doctoral dissertations
Quantifying Lipid Contents in Enveloped Virus Particles with Plasmonic Nanoparticles
Phosphatidylserine (PS) and monosialotetrahexosylganglioside (GM1) are examples of two host-derived lipids in the membrane of enveloped virus particles that are known to contribute to virus attachment, uptake, and ultimately dissemination. A quantitative characterization of their contribution to the functionality of the virus requires information about their relative concentrations in the viral membrane. Here, a gold nanoparticle (NP) binding assay for probing relative PS and GM1 lipid concentrations in the outer leaflet of different HIV-1 and Ebola virus-like particles (VLPs) using sample sizes of less than 3 × 106 particles is introduced. The assay evaluates both scattering intensity and resonance wavelength, and determines relative NP densities through plasmon coupling as a measure for the target lipid concentrations in the NP-labeled VLP membrane. A correlation of the optical observables with absolute lipid contents is achieved by calibration of the plasmon coupling-based methodology with unilamellar liposomes of known PS or GM1 concentration. The performed studies reveal significant differences in the membrane of VLPs that assemble at different intracellular sites and pave the way to an optical quantification of lipid concentration in virus particles at physiological titers.NIH grants RO1CA138509 (B.M.R.), RO1A1064099 (S. G., and 1R56Al104393 (B.M.R. and S. G.; Ethan Edmonds support (CHE 1156666
Metabolic Defects Caused by High-Fat Diet Modify Disease Risk through Inflammatory and Amyloidogenic Pathways in a Mouse Model of Alzheimer’s Disease
High-fat diet (HFD) has been shown to accelerate Alzheimer’s disease (AD) pathology, but the exact molecular and cellular mechanisms remain incompletely understood. Moreover, it is unknown whether AD mice are more susceptible to HFD-induced metabolic dysfunctions. To address these questions, we used 5xFAD mice as an Alzheimer’s disease model to study the physiological and molecular underpinning between HFD-induced metabolic defects and AD pathology. We systematically profiled the metabolic parameters, the gut microbiome composition, and hippocampal gene expression in 5xFAD and wild type (WT) mice fed normal chow diet and HFD. HFD feeding impaired energy metabolism in male 5xFAD mice, leading to increased locomotor activity, energy expenditure, and food intake. 5xFAD mice on HFD had elevated circulating lipids and worsened glucose intolerance. HFD caused profound changes in gut microbiome compositions, though no difference between genotype was detected. We measured hippocampal mRNAs related to AD neuropathology and neuroinflammation and showed that HFD elevated the expression of apoptotic, microglial, and amyloidogenic genes in 5xFAD mice. Pathway analysis revealed that differentially regulated genes were involved in insulin signaling, cytokine signaling, cellular stress, and neurotransmission. Collectively, our results showed that 5xFAD mice were more susceptible to HFD-induced metabolic dysregulation and suggest that targeting metabolic dysfunctions can ameliorate AD symptoms via effects on insulin signaling and neuroinflammation in the hippocampus
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Shale Oil Value Enhancement Research. Quarterly Report, June 1 - August 31, 1996
The overall objective is to develop a new technology for manufacturing valuable marketable products from shale oil. The quarter`s efforts were concentrated on (a) THDA and reaction of alkylpyridines at elevated conditions, (b) compound type analysis of kerogen oil and its derived products, (b) thermal hydrodealkylation of the > 290{degrees}C polar fraction, (c) secondary reactions of pyridinic type compounds to form marketable products, and (d) preparation of presentation to the Dawnbreaker Commercial Assistance Program. Excellent progress is being made in all cases. Our market analysis and industrial feedback indicate that the low molecular weight pyridines are the main market driving force. We are concentrating our effort toward increasing the yield of ``light`` pyridines before the end of Phase II(a). Our current laboratory set-up can only produce analytical quantity of samples, which is not sufficient for marketing purpose. However, the completion of a secondary flow THDA unit for a pilot-scale production depends on the availability of the Phase-II(b) and Phase-III funding
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Shale Oil Value Enhancement Research. Quarterly Report, March 1 - May 31, 1996
The overall objective is to develop a new technology for manufacturing valuable marketable products from shale oil. Phase I objectives are to identify desirable components in shale oil, develop separations techniques for those components, identify market needs and to identify plausible products manufacturable from raw shale oil to meet those needs. The quarter`s efforts were concentrated on (a) compound type analysis of shale oil and its extraction products, (b) thermal hydrodealkylation of the >290{degrees}C polar fraction, (c) reaction of pyridinic type compounds to form secondary products, (d) updating SPX economic analysis, and (e) preparation of a business plan for presentation before the Dawnbreaker Commercial Assistance Program. The subcontract on the thermal hydrodealkylation work at the University of Utah ended at May 3 1, 1996. We have obtained valuable information from the batch experiments. The progress on the flow reactor proved somewhat limited because of the restriction of the existing reactor configuration. The liaison with potential industrial partners is continuing. An additional company has reached agreement to proceed with a geochemical testing of shale oil derived products
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