Gluon fusion contribution to W+W- + jet production

We describe the computation of the $gg \to W^+W^-g$ process that contributes to the production of two $W$-bosons and a jet at the CERN Large Hadron Collider (LHC). While formally of next-to-next-to-leading order (NNLO) in QCD, this process can be evaluated separately from the bulk of NNLO QCD corrections because it is finite and gauge-invariant. It is also enhanced by the large gluon flux and by selection cuts employed in the Higgs boson searches in the decay channel $H \to W^+W^-$, as was first pointed out by Binoth {\it et al.} in the context of $gg \to W^+W^-$ production. For cuts employed by the ATLAS collaboration, we find that the gluon fusion contribution to $pp \to W^+W^-j$ enhances the background by about ten percent and can lead to moderate distortions of kinematic distributions which are instrumental for the ongoing Higgs boson searches at the LHC. We also release a public code to compute the NLO QCD corrections to this process, in the form of an add-on to the package {\tt MCFM}.Comment: 13 pages, 4 figures, 3 table

Social media policies at US medical schools

Background/Purpose: Today's medical students are learning in a social media era in which patient confidentiality is at risk yet schools’ social media policies have not been elucidated. The purpose of this study is to describe the presence of medical schools on top social media sites and to identify whether student policies for these schools explicitly address social media use. Method: Websites of all 132 accredited US medical schools were independently assessed by two investigators for their presence (as of March 31, 2010) on the most common social networking and microblogging sites (Facebook and Twitter) and their publicly available policies addressing online social networking. Key features from these policies are described. Results: 100% (n=132) of US medical schools had websites and 95.45% (126/132) had any Facebook presence. 25.76% (34/132) had official medical school pages, 71.21% (94/132) had student groups, and 54.55% (72/132) had alumni groups on Facebook. 10.6% of medical schools (14/132) had Twitter accounts. 128 of 132 medical schools (96.97%) had student guidelines or policies publicly available online. 13 of these 128 schools (10.16%) had guidelines/policies explicitly mentioning social media. 38.46% (5/13) of these guidelines included statements that defined what is forbidden, inappropriate, or impermissible under any circumstances, or mentioned strongly discouraged online behaviors. 53.85% (7/13) encouraged thoughtful and responsible social media use. Conclusions: Medical schools and their students are using social media. Almost all US medical schools have a Facebook presence, yet most do not have policies addressing student online social networking behavior. While social media use rises, policy informing appropriate conduct in medical schools lags behind. Established policies at some medical schools can provide a blueprint for others to adopt and adapt

Cytoplasmic accumulation of cdc25B phosphatase in mitosis triggers centrosomal microtubule nucleation in HeLa cells

The formation of the mitotic spindle is an essential prerequisite for successful mitosis. The dramatic changes in the level of microtubule (Mt) nucleation at the centrosomes and Mt dynamics that occur in prophase are presumed to be initiated through the activity of cdc2/cyclin B, Here we present data that the cdc25B isoform functions to activate the cytoplasmic pool of cdc2/cyclin B responsible for these events. In contrast to cdc25C, cdc25B is present at low levels in HeLa cells during interphase, but sharply increases in prophase, when cdc25B accumulation in the cytoplasm correlates with prophase spindle formation. Overexpression of wild type and dominant negative mutants of cdc25B and cdc25C shows that prophase Mt nucleation is a consequence of cytoplasmic cdc25B activity, and that cdc25C regulates nuclear G(2)/M events, Our data also suggest that the functional status of the centrosome can regulate nuclear mitotic events

Branes and fluxes in special holonomy manifolds and cascading field theories

We conduct a study of holographic RG flows whose UV is a theory in 2+1 dimensions decoupled from gravity, and the IR is the N=6,8 superconformal fixed point of ABJM. The solutions we consider are constructed by warping the M-theory background whose eight spatial dimensions are manifolds of special holonomies sp(1) times sp(1) and spin(7). Our main example for the spin(7) holonomy manifold is the A8 geometry originally constructed by Cvetic, Gibbons, Lu, and Pope. On the gravity side, our constructions generalize the earlier construction of RG flow where the UV was N=3 Yang-Mills-Chern-Simons matter system and are simpler in a number of ways. Through careful consideration of Page, Maxwell, and brane charges, we identify the discrete and continuous parameters characterizing each system. We then determine the range of the discrete data, corresponding to the flux/rank for which the supersymmetry is unbroken, and estimate the dynamical supersymmetry breaking scale as a function of these data. We then point out the similarity between the physics of supersymmetry breaking between our system and the system considered by Maldacena and Nastase. We also describe the condition for unbroken supersymmetry on class of construction based on a different class of spin(7) manifolds known as B8 spaces whose IR is different from that of ABJM and exhibit some interesting features.Comment: 51 pages, 12 figures. Update in quantization of G4 on B8 in equations (5.12) and (5.13

Use of a porous membrane for gas bubble removal in microfluidic channels: physical mechanisms and design criteria

We demonstrate and explain a simple and efficient way to remove gas bubbles from liquid-filled microchannels, by integrating a hydrophobic porous membrane on top of the microchannel. A prototype chip is manufactured in hard, transparent polymer with the ability to completely filter gas plugs out of a segmented flow at rates up to 7.4 microliter/s per mm2 of membrane area. The device involves a bubble generation section and a gas removal section. In the bubble generation section, a T-junction is used to generate a train of gas plugs into a water stream. These gas plugs are then transported towards the gas removal section, where they slide along a hydrophobic membrane until complete removal. The system has been successfully modeled and four necessary operating criteria have been determined to achieve a complete separation of the gas from the liquid. The first criterion is that the bubble length needs to be larger than the channel diameter. The second criterion is that the gas plug should stay on the membrane for a time sufficient to transport all the gas through the membrane. The third criterion is that the gas plug travel speed should be lower than a critical value: otherwise a stable liquid film between the bubble and the membrane prevents mass transfer. The fourth criterion is that the pressure difference across the membrane should not be larger than the Laplace pressure to prevent water from leaking through the membrane

Real-time correlators in warped AdS/CFT correspondence

We study real-time correlators in the warped AdS/CFT correspondence. We apply the prescription used in the usual AdS/CFT correspondence and obtain the retarded Green's functions for the scalar and vector fields in the spacelike warped and the null warped black hole backgrounds. We find that the retarded Green's functions and the cross sections are well consistent with the predictions from dual CFT. Our results not only support strongly the conjectured warped AdS/CFT correspondence, but also show that the usual relativistic AdS/CFT prescription of obtaining the real-time correlators remain effective in more general backgrounds with anisotropic conformal infinity.Comment: 27 page

LHC Discovery Potential for Non-Standard Higgs Bosons in the 3b Channel

In a variety of well motivated models, such as two Higgs Doublet Models (2HDMs) and the Minimal Supersymmetric Standard Model (MSSM), there are neutral Higgs bosons that have significantly enhanced couplings to b-quarks and tau leptons in comparison to those of the SM Higgs. These so called non-standard Higgs bosons could be copiously produced at the LHC in association with b quarks, and subsequently decay into b-quark pairs. However, this production channel suffers from large irreducible QCD backgrounds. We propose a new search strategy for non-standard neutral Higgs bosons at the 7 TeV LHC in the 3b's final state topology. We perform a simulation of the signal and backgrounds, using state of the art tools and methods for different sets of selection cuts, and conclude that neutral Higgs bosons with couplings to b-quarks of about 0.3 or larger, and masses up to 400 GeV, could be seen with a luminosity of 30 fb^{-1}. In the case of the MSSM we also discuss the complementarity between the 3b channel and the inclusive tau pair channel in exploring the supersymmetric parameter space.Comment: 14 pages, 3 figures, 4 tables, references added, published versio

String Theory on Warped AdS_3 and Virasoro Resonances

We investigate aspects of holographic duals to time-like warped AdS_3 space-times--which include G\"odel's universe--in string theory. Using worldsheet techniques similar to those that have been applied to AdS_3 backgrounds, we are able to identify space-time symmetry algebras that act on the dual boundary theory. In particular, we always find at least one Virasoro algebra with computable central charge. Interestingly, there exists a dense set of points in the moduli space of these models in which there is actually a second commuting Virasoro algebra, typically with different central charge than the first. We analyze the supersymmetry of the backgrounds, finding related enhancements, and comment on possible interpretations of these results. We also perform an asymptotic symmetry analysis at the level of supergravity, providing additional support for the worldsheet analysis.Comment: 24 pages + appendice

Multiple Independent Genetic Factors at NOS1AP Modulate the QT Interval in a Multi-Ethnic Population

Extremes of electrocardiographic QT interval are associated with increased risk for sudden cardiac death (SCD); thus, identification and characterization of genetic variants that modulate QT interval may elucidate the underlying etiology of SCD. Previous studies have revealed an association between a common genetic variant in NOS1AP and QT interval in populations of European ancestry, but this finding has not been extended to other ethnic populations. We sought to characterize the effects of NOS1AP genetic variants on QT interval in the multi-ethnic population-based Dallas Heart Study (DHS, n = 3,072). The SNP most strongly associated with QT interval in previous samples of European ancestry, rs16847548, was the most strongly associated in White (P = 0.005) and Black (P = 3.6×10−5) participants, with the same direction of effect in Hispanics (P = 0.17), and further showed a significant SNP × sex-interaction (P = 0.03). A second SNP, rs16856785, uncorrelated with rs16847548, was also associated with QT interval in Blacks (P = 0.01), with qualitatively similar results in Whites and Hispanics. In a previously genotyped cohort of 14,107 White individuals drawn from the combined Atherosclerotic Risk in Communities (ARIC) and Cardiovascular Health Study (CHS) cohorts, we validated both the second locus at rs16856785 (P = 7.63×10−8), as well as the sex-interaction with rs16847548 (P = 8.68×10−6). These data extend the association of genetic variants in NOS1AP with QT interval to a Black population, with similar trends, though not statistically significant at P<0.05, in Hispanics. In addition, we identify a strong sex-interaction and the presence of a second independent site within NOS1AP associated with the QT interval. These results highlight the consistent and complex role of NOS1AP genetic variants in modulating QT interval

How To Perform Meaningful Estimates of Genetic Effects

Although the genotype-phenotype map plays a central role both in Quantitative and Evolutionary Genetics, the formalization of a completely general and satisfactory model of genetic effects, particularly accounting for epistasis, remains a theoretical challenge. Here, we use a two-locus genetic system in simulated populations with epistasis to show the convenience of using a recently developed model, NOIA, to perform estimates of genetic effects and the decomposition of the genetic variance that are orthogonal even under deviations from the Hardy-Weinberg proportions. We develop the theory for how to use this model in interval mapping of quantitative trait loci using Halley-Knott regressions, and we analyze a real data set to illustrate the advantage of using this approach in practice. In this example, we show that departures from the Hardy-Weinberg proportions that are expected by sampling alone substantially alter the orthogonal estimates of genetic effects when other statistical models, like F2 or G2A, are used instead of NOIA. Finally, for the first time from real data, we provide estimates of functional genetic effects as sets of effects of natural allele substitutions in a particular genotype, which enriches the debate on the interpretation of genetic effects as implemented both in functional and in statistical models. We also discuss further implementations leading to a completely general genotype-phenotype map