Heavy Quark Mass Effects in Deep Inelastic Scattering and Global QCD Analysis

A new implementation of the general PQCD formalism of Collins, including heavy quark mass effects, is described. Important features that contribute to the accuracy and efficiency of the calculation of both neutral current (NC) and charged current (CC) processess are explicitly discussed. This new implementation is applied to the global analysis of the full HERA I data sets on NC and CC cross sections, with correlated systematic errors, in conjunction with the usual fixed-target and hadron collider data sets. By using a variety of parametrizations to explore the parton parameter space, robust new parton distribution function (PDF) sets (CTEQ6.5) are obtained. The new quark distributions are consistently higher in the region x ~ 10^{-3} than previous ones, with important implications on hadron collider phenomenology, especially at the LHC. The uncertainties of the parton distributions are reassessed and are compared to the previous ones. A new set of CTEQ6.5 eigenvector PDFs that encapsulates these uncertainties is also presented.Comment: 32 pages, 12 figures; updated, Publication Versio

Role of free fatty acids in endothelial dysfunction

© 2017 The Author(s). Plasma free fatty acids levels are increased in subjects with obesity and type 2 diabetes, playing detrimental roles in the pathogenesis of atherosclerosis and cardiovascular diseases. Increasing evidence showing that dysfunction of the vascular endothelium, the inner lining of the blood vessels, is the key player in the pathogenesis of atherosclerosis. In this review, we aimed to summarize the roles and the underlying mechanisms using the evidence collected from clinical and experimental studies about free fatty acid-mediated endothelial dysfunction. Because of the multifaceted roles of plasma free fatty acids in mediating endothelial dysfunction, elevated free fatty acid level is now considered as an important link in the onset of endothelial dysfunction due to metabolic syndromes such as diabetes and obesity. Free fatty acid-mediated endothelial dysfunction involves several mechanisms including impaired insulin signaling and nitric oxide production, oxidative stress, inflammation and the activation of the renin-angiotensin system and apoptosis in the endothelial cells. Therefore, targeting the signaling pathways involved in free fatty acid-induced endothelial dysfunction could serve as a preventive approach to protect against the occurrence of endothelial dysfunction and the subsequent complications such as atherosclerosis.Link_to_subscribed_fulltex

Hera Events, Tevatron Jets, and the Uncertainty On Quarks At Large X

The recently reported excess of events at HERA compared to QCD calculations impels us to examine all possible Standard Model explanations before invoking ``new physics''. We explore the possibility of adding an unusual, but small, component of additional quarks at large x (beyond x>0.75) as a way to increase the predicted SM cross-section in the HERA kinematic region by the QCD evolution feed-down effect. We describe various scenarios under which this can be achieved while maintaining good global fits to all established data sets. This implies a much larger SM uncertainty than commonly assumed. In addition, the modified parton distributions provide another possible mechanism to account for the CDF high-pt jet excess which occurs at similar x and Q^2 values.Comment: 13 page Latex, 8 ps figures, replaced with modifications to the tex

Large-x Parton Distributions

Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x>0.1. We examine the status of the gluon and quark distributions in light of new questions that have been raised in the past two years about "large-x" parton distributions, as well as recent measurements which have improved the parton uncertainties. Finally, we provide a status report of the data used in the global analysis, and note some of the open issues where future experiments, including those planned for Jefferson Labs, might contribute.Comment: LaTeX, 9 pages, 7 figures. Invited talk presented at the ``Workshop on Nucleon Structure in the High x-Bjorken Region (HiX2000),'' Temple University, Philadelphia, Pennsylvania, March 30-April 1, 200

The Strange Parton Distribution of the Nucleon: Global Analysis and Applications

The strangeness degrees of freedom in the parton structure of the nucleon are explored in the global analysis framework, using the new CTEQ6.5 implementation of the general mass perturbative QCD formalism of Collins. We systematically determine the constraining power of available hard scattering experimental data on the magnitude and shape of the strange quark and anti-quark parton distributions. We find that current data favor a distinct shape of the strange sea compared to the isoscalar non-strange sea. A new reference parton distribution set, CTEQ6.5S0, and representative sets spanning the allowed ranges of magnitude and shape of the strange distributions, are presented. Some applications to physical processes of current interest in hadron collider phenomenology are discussed.Comment: 19 pages; revised version submitted to JHE

Analysis of the cardiovascular risk factors in military above 35 years old

Introduction The increasing prevalence of cardiovascular risk factors is mainly due to habits acquired during one’s life. However, military training has physical aptitude as one of its main objectives. The objective of the data analysis was to analyze the practiced physical activity, which is the most active age group and if the intensity of the physical activity influences the various parameters being analyzed. Methodology This evaluation focuses on some cardiovascular parameters like the incidence of family history, medication, smoking habits and blood pressure/heart frequency measurements; data from blood tests to examine the biochemistry; body composition through weight, height, abdominal perimeter and, through DXA, body fat; and with accelerometry the physical activity level has been determined. Results Sedentary physical activity is significantly greater during weekends instead of moderate and intense levels, which occur mainly during work-days. People who are between 45 and 54 years old are the ones who takes more anticholesterolemic medicine and also the one who show the best HDL values. The sedentary level of physical activity is positively and directly related with weight, which presents an inverse correlation with moderate physical activity, and also body fat parameters and abdominal perimeter. The highest prothrombin time levels and sedimentation speed are associated with sedentary physical activity. However, even though HDL levels are significantly greater when intense physical activity is practiced, this also creates higher values of INR. Intense physical activity is also responsible for some ischemic heart disease, reflecting an increase in CK-MB values. Discussion The abdominal perimeter proved to be a better predictor of intra-abdominal fat than the BMI. The youngest age group showed really high values of PCR, protein being a contributing factor for heart disease risk (Albert, Glynn & Ridker, 2003). The relation between physical activity and fat was inverse (Cederberg et al, 2011), while HDL results were better as physical activity increased (Gordon-Larsen et al, 2009). Physical activity intensity above average show little to no benefits (AAdahl, KJæer & Jørgensen, 2007), just like the increase of circulation CK-MB however, sedentary ones showed more changes when it came to coagulation. Balanced physical activity was moderate when it came to benefits/disadvantages

Accurate QCD predictions for heavy-quark jets at the Tevatron and LHC

Heavy-quark jets are important in many of today's collider studies and searches, yet predictions for them are subject to much larger uncertainties than for light jets. This is because of strong enhancements in higher orders from large logarithms, ln(p_t/m_Q). We propose a new definition of heavy-quark jets, which is free of final-state logarithms to all orders and such that all initial-state collinear logarithms can be resummed into the heavy-quark parton distributions. Heavy-jet spectra can then be calculated in the massless approximation, which is simpler than a massive calculation and reduces the theoretical uncertainties by a factor of three. This provides the first ever accurate predictions for inclusive b- and c-jets, and the latter have significant discriminatory power for the intrinsic charm content of the proton. The techniques introduced here could be used to obtain heavy-flavour jet results from existing massless next-to-leading order calculations for a wide range of processes. We also discuss the experimental applicability of our flavoured jet definition.Comment: 22 pages, 7 figure