603 research outputs found

    Smoking-gun signatures of little Higgs models

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    Little Higgs models predict new gauge bosons, fermions and scalars at the TeV scale that stabilize the Higgs mass against quadratically divergent one-loop radiative corrections. We categorize the many little Higgs models into two classes based on the structure of the extended electroweak gauge group and examine the experimental signatures that identify the little Higgs mechanism in addition to those that identify the particular little Higgs model. We find that by examining the properties of the new heavy fermion(s) at the LHC, one can distinguish the structure of the top quark mass generation mechanism and test the little Higgs mechanism in the top sector. Similarly, by studying the couplings of the new gauge bosons to the light Higgs boson and to the Standard Model fermions, one can confirm the little Higgs mechanism and determine the structure of the extended electroweak gauge group.Comment: 59 pages, 10 figures. v2: refs added, typos fixed, JHEP versio

    DPP4 Truncated GM-CSF & IL-3 Manifest Distinct Receptor Binding & Regulatory Functions Compared to their Full Length Forms

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    Dipeptidylpeptidase 4 (DPP4/CD26) enzymatically cleaves select penultimate amino acids of proteins, including colony stimulating factors (CSFs), and has been implicated in cellular regulation. To better understand the role of DPP4 regulation of hematopoiesis, we analyzed the activity of DPP4 on the surface of immature blood cells and then comparatively assessed the interactions and functional effects of full-length (FL) and DPP4 truncated factors [(T)-GM-CSF and- IL-3] on both in vitro and in vivo models of normal and leukemic cells. T-GM-CSF and T-IL-3 had enhanced receptor binding, but decreased CSF activity, compared to their FL forms. Importantly, T-GM-CSF and T-IL-3 significantly, and reciprocally, blunted receptor binding and myeloid progenitor cell proliferation activity of both FL-GM-CSF and FL-IL-3 in vitro and in vivo. Similar effects were apparent in vitro using cluster forming cells from patients with Acute Myeloid Leukemia (AML) regardless of cytogenetic or molecular alterations and in vivo utilizing animal models of leukemia. This suggests that DPP4 T-molecules have modified binding and functions compared to their FL counterparts and may serve regulatory roles in normal and malignant hematopoiesis

    On the pivotal role of PPARa in adaptation of the heart to hypoxia and why fat in the diet increases hypoxic injury

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    The role of peroxisome proliferator activated alpha (PPARα) -mediated metabolic remodeling in cardiac adaptation to hypoxia has yet to be defined. Here, mice were housed in hypoxia for 3 weeks before in vivo contractile function was measured using cine magnetic resonance (MR) imaging. In isolated, perfused hearts, energetics were measured using 31P MR spectroscopy and glycolysis and fatty acid oxidation were measured using 3H labelling. Compared with normoxic, chow-fed control mouse heart, hypoxia decreased PPARα expression, fatty acid oxidation and mitochondrial UCP3 levels, while increasing glycolysis, all of which served to maintain normal ATP concentrations and thereby ejection fractions. A high-fat diet increased cardiac PPARα expression, fatty acid oxidation and UCP3 levels, with decreased glycolysis. Hypoxia was unable to alter the high PPARα expression or reverse the metabolic changes caused by the high fat diet, with the result that ATP concentrations and contractile function decreased significantly. The adaptive metabolic changes caused by hypoxia in control mouse hearts were found to have already occurred in PPARα-/- mouse hearts, and sustained function in hypoxia despite an inability for further metabolic remodelling. We conclude that decreased cardiac PPARα expression is essential for adaptive metabolic remodelling in hypoxia, but is prevented by dietary fat

    Spatio-Temporal Variation in Length-Weight Relationships and Condition of the Ribbonfish Trichiurus lepturus (Linnaeus, 1758): Implications for Fisheries Management

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    Knowledge of length-weight relationships for commercially exploited fish is an important tool for assessing and managing of fish stocks. However, analyses of length-weight relationship fisheries data typically do not consider the inherent differences in length-weight relationships for fish caught from different habitats, seasons, or years, and this can affect the utility of these data for developing condition indices or calculating fisheries biomass. Here, we investigated length-weight relationships for ribbonfish Trichiurus lepturus in the waters of the Arabian Sea off Oman collected during three periods (2001-02, 2007-08, and 2014-15) and showed that a multivariate modelling approach that considers the areas and seasons in which ribbonfish were caught improved estimation of length-weight relationships. We used the outputs of these models to explore spatio-temporal variations in condition indices and relative weights among ribbonfish, revealing fish of 85-125 cm were in the best overall condition. We also found that condition differed according to where and when fish were caught, with condition lowest during spring and pre-south-west monsoon periods and highest during and after the south-west monsoons. We interpret these differences to be a consequence of variability in temperature and food availability. Based on our findings, we suggest fishing during seasons that have the lowest impact on fish condition and which are commercially most viable; such fishery management would enhance fisheries conservation and economic revenue in the region

    The meaning of negation in the second language classroom: evidence from 'any'

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    This article brings together an experimental study involving L2 knowledge of negation in English and an analysis of how English language textbooks treat negation, in order to consider whether textbook explanations of negation could better exploit linguistic insights into negation. We focus on the English negative polarity item any, whose distribution is contingent on negation, whether through the explicit negator not or through lexical semantic negators (e.g. hardly). Our experiment compares Chinese-speaking learners with existing data from Arabic-speaking learners, finding lower accuracy on any with lexical semantic negators in both groups. Our textbook analysis reveals an approach to negation that is limited to form, focusing on the explicit negator not without explicit treatment of other types of negation. We propose that emphasizing the meaning of negation, with explicit treatment of the full range of negative forms could facilitate more complete acquisition across a range of grammatical properties where negation plays a role

    Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas

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    This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin
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