1,241 research outputs found
Noncommutative geometry inspired black holes in higher dimensions at the LHC
When embedding models of noncommutative geometry inspired black holes into
the peridium of large extra dimensions, it is natural to relate the
noncommutativity scale to the higher-dimensional Planck scale. If the Planck
scale is of the order of a TeV, noncommutative geometry inspired black holes
could become accessible to experiments. In this paper, we present a detailed
phenomenological study of the production and decay of these black holes at the
Large Hadron Collider (LHC). Noncommutative inspired black holes are relatively
cold and can be well described by the microcanonical ensemble during their
entire decay. One of the main consequences of the model is the existence of a
black hole remnant. The mass of the black hole remnant increases with
decreasing mass scale associated with noncommutative and decreasing number of
dimensions. The experimental signatures could be quite different from previous
studies of black holes and remnants at the LHC since the mass of the remnant
could be well above the Planck scale. Although the black hole remnant can be
very heavy, and perhaps even charged, it could result in very little activity
in the central detectors of the LHC experiments, when compared to the usual
anticipated black hole signatures. If this type of noncommutative inspired
black hole can be produced and detected, it would result in an additional mass
threshold above the Planck scale at which new physics occurs.Comment: 21 pages, 7 figure
Genome Sequencing Reveals Widespread Virulence Gene Exchange among Human Neisseria Species
Commensal bacteria comprise a large part of the microbial world, playing important roles in human development, health and disease. However, little is known about the genomic content of commensals or how related they are to their pathogenic counterparts. The genus Neisseria, containing both commensal and pathogenic species, provides an excellent opportunity to study these issues. We undertook a comprehensive sequencing and analysis of human commensal and pathogenic Neisseria genomes. Commensals have an extensive repertoire of virulence alleles, a large fraction of which has been exchanged among Neisseria species. Commensals also have the genetic capacity to donate DNA to, and take up DNA from, other Neisseria. Our findings strongly suggest that commensal Neisseria serve as reservoirs of virulence alleles, and that they engage extensively in genetic exchange
Search for time-dependent B0s - B0s-bar oscillations using a vertex charge dipole technique
We report a search for B0s - B0s-bar oscillations using a sample of 400,000
hadronic Z0 decays collected by the SLD experiment. The analysis takes
advantage of the electron beam polarization as well as information from the
hemisphere opposite that of the reconstructed B decay to tag the B production
flavor. The excellent resolution provided by the pixel CCD vertex detector is
exploited to cleanly reconstruct both B and cascade D decay vertices, and tag
the B decay flavor from the charge difference between them. We exclude the
following values of the B0s - B0s-bar oscillation frequency: Delta m_s < 4.9
ps-1 and 7.9 < Delta m_s < 10.3 ps-1 at the 95% confidence level.Comment: 18 pages, 3 figures, replaced by version accepted for publication in
Phys.Rev.D; results differ slightly from first versio
Latent Class Analysis of Sexual Risk Patterns Among Esquineros (Street Corner Men) a Group of Heterosexually Identified, Socially Marginalized Men in Urban Coastal Peru
We explored patterns of sexual risk behavior among esquineros, heterosexually-identified, socially-marginalized Peruvian men using latent class analysis. We used data from the Peru site of the National Institute of Mental Health (NIMH) Collaborative HIV/STD Prevention Trial which included n = 2,109 heterosexually-identified men. The latent class analysis used seven risk behaviors to group esquineros into risk classes. We identified four latent classes, of which two classes had lower probabilities and two classes had higher probabilities of these risk behaviors. Comparing the two lower risk classes to the two higher risk classes yielded significantly more unprotected sex acts (Chi square P value < 0.001). The risk behaviors in two of the latent classes identified were primarily related to alcohol and drug use. Future HIV/STI prevention interventions may benefit from this information by tailoring messages to fit the observed risk patterns and should focus on drug and alcohol use
Measurement of the top quark mass using the matrix element technique in dilepton final states
We present a measurement of the top quark mass in pp¯ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. The data were collected by the D0 experiment corresponding to an integrated luminosity of 9.7 fb−1. The matrix element technique is applied to tt¯ events in the final state containing leptons (electrons or muons) with high transverse momenta and at least two jets. The calibration of the jet energy scale determined in the lepton+jets final state of tt¯ decays is applied to jet energies. This correction provides a substantial reduction in systematic uncertainties. We obtain a top quark mass of mt=173.93±1.84 GeV
“Genes”
In order to describe a cell at molecular level, a notion of a “gene” is neither necessary nor helpful. It is sufficient to consider the molecules (i.e., chromosomes, transcripts, proteins) and their interactions to describe cellular processes. The downside of the resulting high resolution is that it becomes very tedious to address features on the organismal and phenotypic levels with a language based on molecular terms. Looking for the missing link between biological disciplines dealing with different levels of biological organization, we suggest to return to the original intent behind the term “gene”. To this end, we propose to investigate whether a useful notion of “gene” can be constructed based on an underlying notion of function, and whether this can serve as the necessary link and embed the various distinct gene concepts of biological (sub)disciplines in a coherent theoretical framework. In reply to the Genon Theory recently put forward by Klaus Scherrer and Jürgen Jost in this journal, we shall discuss a general approach to assess a gene definition that should then be tested for its expressiveness and potential cross-disciplinary relevance
Evaluating movement disorders in pediatric patients receiving risperidone: a comparison of spontaneous reports and research criteria for TD
<p>Abstract</p> <p>Background</p> <p>Movement disorders (MD) in children are relatively common and may be associated with medication use. Objective methods (ie rating scales) and specific research criteria may be helpful in identifying MD-related adverse events that would otherwise not be apparent from spontaneous reports. We assessed whether more stringent and rigorous criteria would provide MD rates similar to those derived subjectively from spontaneous reports.</p> <p>Methods</p> <p>MDs were assessed in children with disruptive behavior disorders (DBDs) and subaverage intelligence receiving risperidone. Data were from three 1-year, open-label studies in subjects 4–14 years old. Dyskinesia severity was rated by the Extrapyramidal Symptom Rating Scale (ESRS) dyskinesia subscale. Tardive dyskinesia (TD) was defined: mild dyskinesia (scores 2, 3) in two anatomical areas; or moderate dyskinesia (score ≥ 4) in one area for ≥ 4 weeks in subjects without dyskinesia at baseline (scores 0, 1).</p> <p>Results</p> <p>The mean (± SD) age of subjects was 9.4 ± 2.4 years, the mean (± SD) risperidone dose was 1.6 ± 0.7 mg/day, and the mean (± SD) exposure was 317.8 ± 104.5 days. ESRS data were available for 668 subjects. Mean ESRS scores were low throughout the study. At baseline, 655 subjects had no dyskinetic symptoms. One subject met predefined TD criteria after a risperidone dose reduction. Symptoms persisted for 4 weeks, resolving with continued treatment and no dosage change. Two different subjects had TD by spontaneous adverse-event reports, with dyskinetic symptoms at 1–2 visits, and symptoms that resolved after treatment discontinuation. Thirteen subjects had dyskinesia at baseline; their mean ESRS dyskinesia scores decreased at endpoint.</p> <p>Conclusion</p> <p>Using objective rating scales and research criteria, low-dose risperidone was associated with low risk of TD and other MDs in children with DBDs in three large 1-year studies. Careful, objective evaluation of emergent MDs during all stages of treatment is essential for identifying treatment-emergent TD.</p
Observation and study of baryonic B decays: B -> D(*) p pbar, D(*) p pbar pi, and D(*) p pbar pi pi
We present a study of ten B-meson decays to a D(*), a proton-antiproton pair,
and a system of up to two pions using BaBar's data set of 455x10^6 BBbar pairs.
Four of the modes (B0bar -> D0 p anti-p, B0bar -> D*0 p anti-p, B0bar -> D+ p
anti-p pi-, B0bar -> D*+ p anti-p pi-) are studied with improved statistics
compared to previous measurements; six of the modes (B- -> D0 p anti-p pi-, B-
-> D*0 p anti-p pi-, B0bar -> D0 p anti-p pi- pi+, B0bar -> D*0 p anti-p pi-
pi+, B- -> D+ p anti-p pi- pi-, B- -> D*+ p anti-p pi- pi-) are first
observations. The branching fractions for 3- and 5-body decays are suppressed
compared to 4-body decays. Kinematic distributions for 3-body decays show
non-overlapping threshold enhancements in m(p anti-p) and m(D(*)0 p) in the
Dalitz plots. For 4-body decays, m(p pi-) mass projections show a narrow peak
with mass and full width of (1497.4 +- 3.0 +- 0.9) MeV/c2, and (47 +- 12 +- 4)
MeV/c2, respectively, where the first (second) errors are statistical
(systematic). For 5-body decays, mass projections are similar to phase space
expectations. All results are preliminary.Comment: 28 pages, 90 postscript figures, submitted to LP0
Study of CP violation in Dalitz-plot analyses of B0 --> K+K-KS, B+ --> K+K-K+, and B+ --> KSKSK+
We perform amplitude analyses of the decays , , and , and measure CP-violating
parameters and partial branching fractions. The results are based on a data
sample of approximately decays, collected with the
BABAR detector at the PEP-II asymmetric-energy factory at the SLAC National
Accelerator Laboratory. For , we find a direct CP asymmetry
in of , which differs
from zero by . For , we measure the
CP-violating phase .
For , we measure an overall direct CP asymmetry of
. We also perform an angular-moment analysis of
the three channels, and determine that the state can be described
well by the sum of the resonances , , and
.Comment: 35 pages, 68 postscript figures. v3 - minor modifications to agree
with published versio
Measurement of CP-violation asymmetries in D0 to Ks pi+ pi-
We report a measurement of time-integrated CP-violation asymmetries in the
resonant substructure of the three-body decay D0 to Ks pi+ pi- using CDF II
data corresponding to 6.0 invfb of integrated luminosity from Tevatron ppbar
collisions at sqrt(s) = 1.96 TeV. The charm mesons used in this analysis come
from D*+(2010) to D0 pi+ and D*-(2010) to D0bar pi-, where the production
flavor of the charm meson is determined by the charge of the accompanying pion.
We apply a Dalitz-amplitude analysis for the description of the dynamic decay
structure and use two complementary approaches, namely a full Dalitz-plot fit
employing the isobar model for the contributing resonances and a
model-independent bin-by-bin comparison of the D0 and D0bar Dalitz plots. We
find no CP-violation effects and measure an asymmetry of ACP = (-0.05 +- 0.57
(stat) +- 0.54 (syst))% for the overall integrated CP-violation asymmetry,
consistent with the standard model prediction.Comment: 15 page
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