103 research outputs found
Higgs boson decay into 2 photons in the type~II Seesaw Model
We study the two photon decay channel of the Standard Model-like component of
the CP-even Higgs bosons present in the type II Seesaw Model. The corresponding
cross-section is found to be significantly enhanced in parts of the parameter
space, due to the (doubly-)charged Higgs bosons' virtual
contributions, while all the other Higgs decay channels remain Standard
Model(SM)-like. In other parts of the parameter space (and
) interfere destructively, reducing the two photon branching ratio
tremendously below the SM prediction. Such properties allow to account for any
excess such as the one reported by ATLAS/CMS at GeV if confirmed
by future data; if not, for the fact that a SM-like Higgs exclusion in the
diphoton channel around 114-115 GeV as reported by ATLAS, does not contradict a
SM-like Higgs at LEP(!), and at any rate, for the fact that ATLAS/CMS exclusion
limits put stringent lower bounds on the mass, particularly in
the parameter space regions where the direct limits from same-sign leptonic
decays of do not apply.Comment: 26 pages, 7 figure
Anomalous Diffusion Induced by Cristae Geometry in the Inner Mitochondrial Membrane
Diffusion of inner membrane proteins is a prerequisite for correct functionality of mitochondria. The complicated structure of tubular, vesicular or flat cristae and their small connections to the inner boundary membrane impose constraints on the mobility of proteins making their diffusion a very complicated process. Therefore we investigate the molecular transport along the main mitochondrial axis using highly accurate computational methods. Diffusion is modeled on a curvilinear surface reproducing the shape of mitochondrial inner membrane (IM). Monte Carlo simulations are carried out for topologies resembling both tubular and lamellar cristae, for a range of physiologically viable crista sizes and densities. Geometrical confinement induces up to several-fold reduction in apparent mobility. IM surface curvature per se generates transient anomalous diffusion (TAD), while finite and stable values of projected diffusion coefficients are recovered in a quasi-normal regime for short- and long-time limits. In both these cases, a simple area-scaling law is found sufficient to explain limiting diffusion coefficients for permeable cristae junctions, while asymmetric reduction of the junction permeability leads to strong but predictable variations in molecular motion rate. A geometry-based model is given as an illustration for the time-dependence of diffusivity when IM has tubular topology. Implications for experimental observations of diffusion along mitochondria using methods of optical microscopy are drawn out: a non-homogenous power law is proposed as a suitable approach to TAD. The data demonstrate that if not taken into account appropriately, geometrical effects lead to significant misinterpretation of molecular mobility measurements in cellular curvilinear membranes
PGB pair production at LHC and ILC as a probe of the topcolor-assisted technicolor models
The topcolor-assisted technicolor (TC2) model predicts some light pseudo
goldstone bosons (PGBs), which may be accessible at the LHC or ILC. In this
work we study the pair productions of the charged or neutral PGBs at the LHC
and ILC. For the productions at the LHC we consider the processes proceeding
through gluon-gluon fusion and quark-antiquark annihilation, while for the
productions at the ILC we consider both the electron-positron collision and the
photon-photon collision. We find that in a large part of parameter space the
production cross sections at both colliders can be quite large compared with
the low standard model backgrounds. Therefore, in future experiments these
productions may be detectable and allow for probing TC2 model.Comment: 26 pages, 16 figures. slight changes in the text; notations for
curves changed; references adde
Constitutive and Treatment-Induced CXCL8-Signalling Selectively Modulates the Efficacy of Anti-Metabolite Therapeutics in Metastatic Prostate Cancer
<div><h3>Background</h3><p>The current study was undertaken to characterize the effect of anti-metabolites on inducing CXCL8 signaling and determining whether the constitutive and/or drug-induced CXCL8 signaling in metastatic prostate cancer (CaP) cells modulates their sensitivity to this class of agent.</p> <h3>Methods</h3><p>The response of metastatic CaP cells to 5-Fluorouracil (5-FU), Pemetrexed or Tomudex was determined using cell count assays, flow cytometry and PARP cleavage analysis. Quantitative-PCR, ELISA and immunoblots were employed to determine effects of drugs or CXCL8 administration on target gene/protein expression.</p> <h3>Results</h3><p>Administration of 5-FU but not pemetrexed potentiated CXCL8 secretion and increased CXCR1 and CXCR2 gene expression in metastatic PC3 cells. Consistent with this, the inhibition of CXCL8 signaling using a CXCR2 antagonist, AZ10397767, increased the cytotoxicity of 5-FU by 4-fold (P<0.001), and increased 5-FU-induced apoptosis in PC3 cells (P<0.01). In contrast, while administration of AZ10397767 had no effect on the sensitivity of pemetrexed, the CXCR2 antagonist exerted the greatest effect in increasing the sensitivity of PC3 cells to Tomudex, a directed thymidylate synthase (TS) inhibitor. Subsequent experiments confirmed that administration of recombinant human CXCL8 increased TS expression, a response mediated in part by the CXCR2 receptor. Moreover, siRNA-mediated knockdown of the CXCL8-target gene Bcl-2 increased the sensitivity of PC3 cells to 5-FU.</p> <h3>Conclusions</h3><p>CXCL8 signaling provides a selective resistance of metastatic prostate cancer cells to specific anti-metabolites by promoting a target-associated resistance, in addition to underpinning an evasion of treatment-induced apoptosis.</p> </div
Successful Reach and Adoption of a workplace health promotion RCT targeting a group of high-risk workers
<p>Abstract</p> <p>Background</p> <p>Cleaners are rarely introduced to workplace health promotion programs. The study's objective was to evaluate the reach and adoption of a workplace randomized controlled trial (RCT) among cleaners in Denmark.</p> <p>Methods</p> <p>Cleaning businesses with at least 30 employees, that could offer a weekly 1-hour intervention during working hours, were invited to participate. Employees working at least 20 hours/week were invited to answer a screening questionnaire and consent to participate. Analyses determined the differences in health variables between responders and non-responders, consenters and non-consenters, participants and non-participants and between participants of the RCT's three groups: physical coordination training, cognitive-behavioural theory-based training and reference group.</p> <p>Results</p> <p>From 16 eligible workplaces, a representative sample of 50% adopted the trial. Of 758 eligible employees, 78% responded to the screening questionnaire and 49% consented to participate. Consenters and participants differed from non-consenters and non-participants by having higher BMI, more chronic diseases and poorer musculoskeletal health.</p> <p>Conclusions</p> <p>This study indicates that workplace health promotion programs directed at health risk factors among cleaners enable significant adoption and reach to a high-risk subgroup of the Danish workforce.</p> <p>Trial registration</p> <p>Trial registration ISRCTN96241850</p
Properties of Graphene: A Theoretical Perspective
In this review, we provide an in-depth description of the physics of
monolayer and bilayer graphene from a theorist's perspective. We discuss the
physical properties of graphene in an external magnetic field, reflecting the
chiral nature of the quasiparticles near the Dirac point with a Landau level at
zero energy. We address the unique integer quantum Hall effects, the role of
electron correlations, and the recent observation of the fractional quantum
Hall effect in the monolayer graphene. The quantum Hall effect in bilayer
graphene is fundamentally different from that of a monolayer, reflecting the
unique band structure of this system. The theory of transport in the absence of
an external magnetic field is discussed in detail, along with the role of
disorder studied in various theoretical models. We highlight the differences
and similarities between monolayer and bilayer graphene, and focus on
thermodynamic properties such as the compressibility, the plasmon spectra, the
weak localization correction, quantum Hall effect, and optical properties.
Confinement of electrons in graphene is nontrivial due to Klein tunneling. We
review various theoretical and experimental studies of quantum confined
structures made from graphene. The band structure of graphene nanoribbons and
the role of the sublattice symmetry, edge geometry and the size of the
nanoribbon on the electronic and magnetic properties are very active areas of
research, and a detailed review of these topics is presented. Also, the effects
of substrate interactions, adsorbed atoms, lattice defects and doping on the
band structure of finite-sized graphene systems are discussed. We also include
a brief description of graphane -- gapped material obtained from graphene by
attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic
Reporting of clinical trials: a review of research funders' guidelines
BACKGROUND: Randomised controlled trials (RCTs) represent the gold standard methodological design to evaluate the effectiveness of an intervention in humans but they are subject to bias, including study publication bias and outcome reporting bias. National and international organisations and charities give recommendations for good research practice in relation to RCTs but to date no review of these guidelines has been undertaken with respect to reporting bias. METHODS: National and international organisations and UK based charities listed on the Association for Medical Research Charities website were contacted in 2007; they were considered eligible for this review if they funded RCTs. Guidelines were obtained and assessed in relation to what was written about trial registration, protocol adherence and trial publication. It was also noted whether any monitoring against these guidelines was undertaken. This information was necessary to discover how much guidance researchers are given on the publication of results, in order to prevent study publication bias and outcome reporting bias. RESULTS: Seventeen organisations and 56 charities were eligible of 140 surveyed for this review, although there was no response from 12. Trial registration, protocol adherence, trial publication and monitoring against the guidelines were often explicitly discussed or implicitly referred too. However, only eleven of these organisations or charities mentioned the publication of negative as well as positive outcomes and just three of the organisations specifically stated that the statistical analysis plan should be strictly adhered to and all changes should be reported. CONCLUSION: Our review indicates that there is a need to provide more detailed guidance for those conducting and reporting clinical trials to help prevent the selective reporting of results. Statements found in the guidelines generally refer to publication bias rather than outcome reporting bias. Current guidelines need to be updated and include the statement that all primary and secondary outcomes prespecified in the protocol should be fully reported and should not be selected for inclusion in the final report based on their results
Complications related to intraoperative transesophageal echocardiography in liver transplantation
Systematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias
BACKGROUND: The increased use of meta-analysis in systematic reviews of healthcare interventions has highlighted several types of bias that can arise during the completion of a randomised controlled trial. Study publication bias has been recognised as a potential threat to the validity of meta-analysis and can make the readily available evidence unreliable for decision making. Until recently, outcome reporting bias has received less attention. METHODOLOGY/PRINCIPAL FINDINGS: We review and summarise the evidence from a series of cohort studies that have assessed study publication bias and outcome reporting bias in randomised controlled trials. Sixteen studies were eligible of which only two followed the cohort all the way through from protocol approval to information regarding publication of outcomes. Eleven of the studies investigated study publication bias and five investigated outcome reporting bias. Three studies have found that statistically significant outcomes had a higher odds of being fully reported compared to non-significant outcomes (range of odds ratios: 2.2 to 4.7). In comparing trial publications to protocols, we found that 40-62% of studies had at least one primary outcome that was changed, introduced, or omitted. We decided not to undertake meta-analysis due to the differences between studies. CONCLUSIONS: Recent work provides direct empirical evidence for the existence of study publication bias and outcome reporting bias. There is strong evidence of an association between significant results and publication; studies that report positive or significant results are more likely to be published and outcomes that are statistically significant have higher odds of being fully reported. Publications have been found to be inconsistent with their protocols. Researchers need to be aware of the problems of both types of bias and efforts should be concentrated on improving the reporting of trials
Signals in the Soil: An Introduction to Wireless Underground Communications
In this chapter, wireless underground (UG) communications are introduced. A detailed overview of WUC is given. A comprehensive review of research challenges in WUC is presented. The evolution of underground wireless is also discussed. Moreover, different component of UG communications is wireless. The WUC system architecture is explained with a detailed discussion of the anatomy of an underground mote. The examples of UG wireless communication systems are explored. Furthermore, the differences of UG wireless and over-the-air wireless are debated. Different types of wireless underground channel (e.g., In-Soil, Soil-to-Air, and Air-to-Soil) are reported as well
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