Probing anomalous tbW couplings in single-top production using top polarization at the Large Hadron Collider

We study the sensitivity of the Large Hadron Collider (LHC) to anomalous tbW couplings in single-top production in association with a W^- boson followed by semileptonic decay of the top. We calculate top polarization and the effects of these anomalous couplings to it at two centre-of-mass (cm) energies of 7 TeV and 14 TeV. As a measure of top polarization, we look at various laboratory frame distributions of its decay products, viz., lepton angular and energy distributions and b-quark angular distributions, without requiring reconstruction of the rest frame of the top, and study the effect of anomalous couplings on these distributions. We construct certain asymmetries to study the sensitivity of these distributions to anomalous tbW couplings. We find that 1\sigma limits on real and imaginary parts of the dominant anomalous coupling Ref_{2R} which may be obtained by utilizing these asymmetries at the LHC with cm energy of 14 TeV and an integrated luminosity of 10 fb^{-1} will be significantly better than the expectations from direct measurements of cross sections and some other variables at the LHC and over an order of magnitude better than the indirect limits.Comment: 25 pages, 34 figure

High-pressure technology for Sargassum spp biomass pretreatment and fractionation in the third generation of bioethanol production

Sargassum spp is an invasive macroalgae and an alternative feedstock for bioethanol production. Sargassum spp biomass was subjected to high-pressure technology for biomass fractionation under different operating conditions of temperature and residence time to obtain glucan enriched pretreated solids (32.22 g/100 g of raw material). Enzyme hydrolysis process at high pretreated solid loading (13%, w/v) and enzyme loading of 10 FPU/g of glucan was performed, obtaining 43.01 g/L of glucose corresponding to a conversion yield of 92.12%. Finally, a pre-simultaneous saccharification and fermentation strategy (PSSF) was performed to produce bioethanol. This operational strategy produced 45.66 g/L of glucose in the pre-saccharification stage, and 18.14 g/L of bioethanol was produced with a glucose to bioethanol conversion yield of 76.23%. The development of this process highlights the feasibility of bioethanol production from macroalgal biomass in the biorefinery concept

Entry and Fusion of Emerging Paramyxoviruses

Paramyxoviruses are a family of non-segmented RNA viruses that includes major human pathogens such as measles virus and respiratory syncytial virus (RSV) and significant animal viruses like rinderpest. In recent years, several new paramyxoviruses have been identified, further increasing the breadth and importance of this viral family. While many elements of the fusion and entry mechanisms of these recently identified pathogens are conserved, there are interesting differences, including variations in receptor binding, cell tropism, fusion (F) protein proteolytic activation, and triggering of membrane fusion. Thus, study of their entry mechanisms has highlighted the diversity of these critical events in the family

Localization of gravity on a de Sitter thick braneworld without scalar fields

In this work we present a simple thick braneworld model that is generated by an intriguing interplay between a 5D cosmological constant with a de Sitter metric induced in the 3-brane without the inclusion of scalar fields. We show that 4D gravity is localized on this brane, provide analytic expressions for the massive Kaluza-Klein (KK) fluctuation modes and also show that the spectrum of metric excitations displays a mass gap. We finally present the corrections to Newton's law due to these massive modes. This model has no naked singularities along the fifth dimension despite the existence of a mass gap in the graviton spectrum as it happens in thick branes with 4D Poincare symmetry, providing a simple model with very good features: the curvature is completely smooth along the fifth dimension, it localizes 4D gravity and the spectrum of gravity fluctuations presents a mass gap, a fact that rules out the existence of phenomenologically dangerous ultralight KK excitations in the model. We finally present our solution as a limit of scalar thick branes.Comment: 11 pages in latex, no figures, title and abstract changed, a new section and some references adde

Z' signals in polarised top-antitop final states

We study the sensitivity of top-antitop samples produced at all energy stages of the Large Hadron Collider (LHC) to the nature of an underlying Z' boson, in presence of full tree level standard model (SM) background effects and relative interferences. We concentrate on differential mass spectra as well as both spatial and spin asymmetries thereby demonstrating that exploiting combinations of these observables will enable one to distinguish between sequential Z's and those pertaining to Left-Right symmetric models as well as E6 inspired ones, assuming realistic final state reconstruction efficiencies and error estimates.Comment: 21 pages, 6 colour figures, 10 table

Modeling Trap-Awareness and Related Phenomena in Capture-Recapture Studies

Trap-awareness and related phenomena whereby successive capture events are not independent is a feature of the majority of capture-recapture studies. This phenomenon was up to now difficult to incorporate in open population models and most authors have chosen to neglect it although this may have damaging consequences. Focusing on the situation where animals exhibit a trap response at the occasion immediately following one where they have been trapped but revert to their original naïve state if they are missed once, we show that trap-dependence is more naturally viewed as a state transition and is amenable to the current models of capture-recapture. This approach has the potential to accommodate lasting or progressively waning trap effects

Supersymmetric Monojets at the Large Hadron Collider

Supersymmetric monojets may be produced at the Large Hadron Collider by the process qg -> squark neutralino_1 -> q neutralino_1 neutralino_1, leading to a jet recoiling against missing transverse momentum. We discuss the feasibility and utility of the supersymmetric monojet signal. In particular, we examine the possible precision with which one can ascertain the neutralino_1-squark-quark coupling via the rate for monojet events. Such a coupling contains information on the composition of the neutralino_1 and helps bound dark matter direct detection cross-sections and the dark matter relic density of the neutralino_1. It also provides a check of the supersymmetric relation between gauge couplings and gaugino-quark-squark couplings.Comment: 46 pages, 10 figures. The appendix has been rewritten to correct an error that appears in all previous versions of the appendix. This error has no effect on the results in the main body of the pape

Psychomotor impairments and therapeutic implications revealed by a mutation associated with infantile Parkinsonism-Dystonia

Parkinson disease (PD) is a progressive, neurodegenerative disorder affecting over 6.1 million people worldwide. Although the cause of PD remains unclear, studies of highly penetrant mutations identified in early-onset familial parkinsonism have contributed to our understanding of the molecular mechanisms underlying disease pathology. Dopamine (DA) transporter (DAT) deficiency syndrome (DTDS) is a distinct type of infantile parkinsonism-dystonia that shares key clinical features with PD, including motor deficits (progressive bradykinesia, tremor, hypomimia) and altered DA neurotransmission. Here, we define structural, functional, and behavioral consequences of a Cys substitution at R445 in human DAT (hDAT R445C), identified in a patient with DTDS. We found that this R445 substitution disrupts a phylogenetically conserved intracellular (IC) network of interactions that compromise the hDAT IC gate. This is demonstrated by both Rosetta molecular modeling and fine-grained simulations using hDAT R445C, as well as EPR analysis and X-ray crystallography of the bacterial homolog leucine transporter. Notably, the disruption of this IC network of interactions supported a channel-like intermediate of hDAT and compromised hDAT function. We demonstrate that Drosophila melanogaster expressing hDAT R445C show impaired hDAT activity, which is associated with DA dysfunction in isolated brains and with abnormal behaviors monitored at high-speed time resolution. We show that hDAT R445C Drosophila exhibit motor deficits, lack of motor coordination (i.e. flight coordination) and phenotypic heterogeneity in these behaviors that is typically associated with DTDS and PD. These behaviors are linked with altered dopaminergic signaling stemming from loss of DA neurons and decreased DA availability. We rescued flight coordination with chloroquine, a lysosomal inhibitor that enhanced DAT expression in a heterologous expression system. Together, these studies shed some light on how a DTDS-linked DAT mutation underlies DA dysfunction and, possibly, clinical phenotypes shared by DTDS and PD

Glycoprotein Ib activation by thrombin stimulates the energy metabolism in human platelets

<div><p>Thrombin-induced platelet activation requires substantial amounts of ATP. However, the specific contribution of each ATP-generating pathway <i>i</i>.<i>e</i>., oxidative phosphorylation (OxPhos) versus glycolysis and the biochemical mechanisms involved in the thrombin-induced activation of energy metabolism remain unclear. Here we report an integral analysis on the role of both energy pathways in human platelets activated by several agonists, and the signal transducing mechanisms associated with such activation. We found that thrombin, Trap-6, arachidonic acid, collagen, A23187, epinephrine and ADP significantly increased glycolytic flux (3–38 times <i>vs</i>. non-activated platelets) whereas ristocetin was ineffective. OxPhos (33 times) and mitochondrial transmembrane potential (88%) were increased only by thrombin. OxPhos was the main source of ATP in thrombin-activated platelets, whereas in platelets activated by any of the other agonists, glycolysis was the principal ATP supplier. In order to establish the biochemical mechanisms involved in the thrombin-induced OxPhos activation in platelets, several signaling pathways associated with mitochondrial activation were analyzed. Wortmannin and LY294002 (PI3K/Akt pathway inhibitors), ristocetin and heparin (GPIb inhibitors) as well as resveratrol, ATP (calcium-release inhibitors) and PP1 (Tyr-phosphorylation inhibitor) prevented the thrombin-induced platelet activation. These results suggest that thrombin activates OxPhos and glycolysis through GPIb-dependent signaling involving PI3K and Akt activation, calcium mobilization and protein phosphorylation.</p></div