Lysine-Arginine Advanced Glycation End-Product Cross-links and the Effect on Collagen Structure: A Molecular Dynamics Study

The accumulation of advanced glycation end-products is a fundamental process that is central to age-related decline in musculoskeletal tissues and locomotor system function and other collagen-rich tissues. However, although computational studies of advanced glycation end-product cross-links could be immensely valuable, this area remains largely unexplored given the limited availability of structural parameters for the derivation of force fields for Molecular Dynamics simulations. In this article, we present the bonded force constants, atomic partial charges and geometry of the arginine-lysine cross-links DOGDIC, GODIC, and MODIC. We have performed in vacuo Molecular Dynamics simulations to validate their implementation against quantum mechanical frequency calculations. A DOGDIC advanced glycation endproduct cross-link was then inserted into a model collagen fibril to explore structural changes of collagen and dynamics in interstitial water. Unlike our previous studies of glucosepane, our findings suggest that intra-collagen DOGDIC cross-links furthers intra-collagen peptide hydrogen-bonding and does not promote the diffusion of water through the collagen triple helices

Higgs Physics at the Large Hadron Collider

In this talk I will begin by summarising the importance of the Higgs physics studies at the LHC. I will then give a short description of the pre-LHC constraints on the Higgs mass and the theoretical predictions for the LHC along with a discussion of the current experimental results, ending with prospects in the near future at the LHC. In addition to the material covered in the presented talk, I have included in the writeup, a critical appraisal of the theoretical uncertainties in the Higgs cross-sections at the Tevatron as well as a discussion of the recent experimental results from the LHC which have become available since the time of the workshop.Comment: LateX, 12 figures, 15 pages, Presented at the XIth Workshop on High Energy Physics Phenomenology, 2010, Ahmedabad, Indi

Substrate-induced band gap opening in epitaxial graphene

Graphene has shown great application potentials as the host material for next generation electronic devices. However, despite its intriguing properties, one of the biggest hurdles for graphene to be useful as an electronic material is its lacking of an energy gap in the electronic spectra. This, for example, prevents the use of graphene in making transistors. Although several proposals have been made to open a gap in graphene's electronic spectra, they all require complex engineering of the graphene layer. Here we show that when graphene is epitaxially grown on the SiC substrate, a gap of ~ 0.26 is produced. This gap decreases as the sample thickness increases and eventually approaches zero when the number of layers exceeds four. We propose that the origin of this gap is the breaking of sublattice symmetry owing to the graphene-substrate interaction. We believe our results highlight a promising direction for band gap engineering of graphene.Comment: 10 pages, 4 figures; updated reference

Higgs production in CP-violating supersymmetric cascade decays: probing the `open hole' at the Large Hadron Collider

A benchmark CP-violating supersymmetric scenario (known as 'CPX-scenario' in the literature) is studied in the context of the Large Hadron Collider (LHC). It is shown that the LHC, with low to moderate accumulated luminosity, will be able to probe the existing `hole' in the $m_{h_1}$-$\tan\beta$ plane, which cannot be ruled out by the LEP data. We explore the parameter space with cascade decay of third generation squarks and gluino with CP-violating decay branching fractions. We propose a multi-channel analysis to probe this parameter space some of which are background free at an integrated luminosity of 5-10 fb$^{-1}$. Specially, multi-lepton final states (3\l,\, 4\l and like sign di-lepton) are almost background free and have $5\sigma$ reach for the corresponding signals with very early data of LHC for both 14 TeV and 7 TeV center of mass energy.Comment: 24 pages, 9 figures, references added as in the journal versio

Autopsy in adults with congenital heart disease (ACHD).

The adult congenital heart diseases (ACHD) population is exceeding the pediatric congenital heart diseases (CHD) population and is progressively expanding each year, representing more than 90% of patients with CHD. Of these, about 75% have undergone surgical and/or percutaneous intervention for palliation or correction. Autopsy can be a very challenging procedure in ACHD patients. The approach and protocol to be used may vary depending on whether the pathologists are facing native disease without surgical or percutaneous interventions, but with various degrees of cardiac remodeling, or previously palliated or corrected CHD. Moreover, interventions for the same condition have evolved over the last decades, as has perioperative myocardial preservations and postoperative care, with different long-term sequelae depending on the era in which patients were operated on. Careful clinicopathological correlation is, thus, required to assist the pathologist in performing the autopsy and reaching a diagnosis regarding the cause of death. Due to the heterogeneity of the structural abnormalities, and the wide variety of surgical and interventional procedures, there are no standard methods for dissecting the heart at autopsy. In this paper, we describe the most common types of CHDs that a pathologist could encounter at autopsy, including the various types of surgical and percutaneous procedures and major pathological manifestations. We also propose a practical systematic approach to the autopsy of ACHD patients

Does the `Higgs' have Spin Zero?

The Higgs boson is predicted to have spin zero. The ATLAS and CMS experiments have recently reported of an excess of events with mass ~ 125 GeV that has some of the characteristics expected for a Higgs boson. We address the questions whether there is already any evidence that this excess has spin zero, and how this possibility could be confirmed in the near future. The excess observed in the gamma gamma final state could not have spin one, leaving zero and two as open possibilities. We calculate the angular distribution of gamma gamma pairs from the decays of a spin-two boson produced in gluon-gluon collisions, showing that is unique and distinct from the spin-zero case. We also calculate the distributions for lepton pairs that would be produced in the W W* decays of a spin-two boson, which are very different from those in Higgs decays, and note that the kinematics of the event selection used to produce the excess observed in the W W* final state have reduced efficiency for spin two.Comment: 22 pages, 22 figures, Version accepted for publication in JHEP, includes additional plots of dilepton mass distribution

Higgs Physics: Theory

I review the theoretical aspects of the physics of Higgs bosons, focusing on the elements that are relevant for the production and detection at present hadron colliders. After briefly summarizing the basics of electroweak symmetry breaking in the Standard Model, I discuss Higgs production at the LHC and at the Tevatron, with some focus on the main production mechanism, the gluon-gluon fusion process, and summarize the main Higgs decay modes and the experimental detection channels. I then briefly survey the case of the minimal supersymmetric extension of the Standard Model. In a last section, I review the prospects for determining the fundamental properties of the Higgs particles once they have been experimentally observed.Comment: 21 pages, 15 figures. Talk given at the XXV International Symposium on Lepton Photon Interactions at High Energies (Lepton Photon 11), 22-27 August 2011, Mumbai, Indi

Effects of Multi-Surface Modification on Curie temperature of ferroelectric films

Within the framework of mean field theory, we study the effects of multi-surface modification on Curie temperature of ferroelectric films using the transverse Ising model. The general nonlinear equations for Curie temperature of multi-surface ferroelectric films with arbitrary exchange constants and transverse fields are derived by the transfer matrix method. As an example, we consider a film consisting of top surface layers, bulk layers and bottom surface layers. Two types of surface modifications, modifications of a surface exchange constant and a surface transverse field are taken into account. The dependence of Curie temperature on the surface layer numbers, bulk layer numbers, surface exchange constants, surface transverse fields and bulk transverse fields is discussed.Comment: 11 pages, 5 figure

Essential self-adjointness of magnetic Schr\"odinger operators on locally finite graphs

We give sufficient conditions for essential self-adjointness of magnetic Schr\"odinger operators on locally finite graphs. Two of the main theorems of the present paper generalize recent results of Torki-Hamza.Comment: 14 pages; The present version differs from the original version as follows: the ordering of presentation has been modified in several places, more details have been provided in several places, some notations have been changed, two examples have been added, and several new references have been inserted. The final version of this preprint will appear in Integral Equations and Operator Theor

Antenatal atazanavir: a retrospective analysis of pregnancies exposed to atazanavir.

INTRODUCTION: There are few data regarding the tolerability, safety, or efficacy of antenatal atazanavir. We report our clinical experience of atazanavir use in pregnancy. METHODS: A retrospective medical records review of atazanavir-exposed pregnancies in 12 London centres between 2004 and 2010. RESULTS: There were 145 pregnancies in 135 women: 89 conceived whilst taking atazanavir-based combination antiretroviral therapy (cART), "preconception" atazanavir exposure; 27 started atazanavir-based cART as "first-line" during the pregnancy; and 29 "switched" to an atazanavir-based regimen from another cART regimen during pregnancy. Gastrointestinal intolerance requiring atazanavir cessation occurred in five pregnancies. Self-limiting, new-onset transaminitis was most common in first-line use, occurring in 11.0%. Atazanavir was commenced in five switch pregnancies in the presence of transaminitis, two of which discontinued atazanavir with persistent transaminitis. HIV-VL < 50 copies/mL was achieved in 89.3% preconception, 56.5% first-line, and 72.0% switch exposures. Singleton preterm delivery (<37 weeks) occurred in 11.7% preconception, 9.1% first-line, and 7.7% switch exposures. Four infants required phototherapy. There was one mother-to-child transmission in a poorly adherent woman. CONCLUSIONS: These data suggest that atazanavir is well tolerated and can be safely prescribed as a component of combination antiretroviral therapy in pregnancy