410 research outputs found
Immunologic markers of progression to acquired immunodeficiency syndrome are time-dependent and illness-specific
KrĂ€mer A, Biggar RJ, Hampl H, et al. Immunologic markers of progression to acquired immunodeficiency syndrome are time-dependent and illness-specific. American Journal of Epidemiology. 1992;136(1):71-80.Since prevalent cohorts may be biased by the duration of human immunodeficiency virus (HIV) infection (onset bias), it is useful to assess the potential predictive value of markers in incident cohorts of HIV-positive subjects for whom the date of seroconversion is known or can reliably be estimated. Of 131 homosexual men with HIV-1 seroconversion from New York City and Washington, DC, who were evaluated annually beginning in 1982, 60 developed acquired immunodeficiency syndrome (AIDS) by the end of 1989. The prognostic significance of immunologic markers (proportion of CD4+ T-lymphocytes, neopterin, Ă2-microglobulin, serum interferon, and anti-p24 antibody) and of a virologic marker (HIV p24 antigen) was determined using measurements made at defined time intervals after the known or estimated date of HIV seroconversion. When measurements made 3 years after seroconversion were used, all markers except anti-p24 antibody were found to be significant estimators of AIDS risk in univariate analyses. In multivariate Cox regression modeling, the maximum information was obtained by including neopterin, interferon, and the CD4+ T-lymphocyte proportion. The predictive value of markers after HIV seroconversion could change considerably from one interval to another. Elevated levels of Ă2-microglobulin and neopterin significantly predicted the development of Kaposiâs sarcoma. These two markers were highly correlated (r=0. 74). The authors conclude that immunologic markers can be important for an HIV staging system for estimating prognosis and facilitating early therapeutic intervention in HIV-positive patients
The role of executive functions in the control of aggressive behavior
An extensive literature suggests a link between executive functions and aggressive behavior in humans, pointing mostly to an inverse relationship, i.e., increased tendencies toward aggression in individuals scoring low on executive function tests. This literature is limited, though, in terms of the groups studied and the measures of executive functions. In this paper, we present data from two studies addressing these issues. In a first behavioral study, we asked whether high trait aggressiveness is related to reduced executive functions. A sample of over 600 students performed in an extensive behavioral test battery including paradigms addressing executive functions such as the Eriksen Flanker task, Stroop task, n-back task, and Tower of London (TOL). High trait aggressive participants were found to have a significantly reduced latency score in the TOL, indicating more impulsive behavior compared to low trait aggressive participants. No other differences were detected. In an EEG-study, we assessed neural and behavioral correlates of error monitoring and response inhibition in participants who were characterized based on their laboratory-induced aggressive behavior in a competitive reaction time task. Participants who retaliated more in the aggression paradigm and had reduced frontal activity when being provoked did not, however, show any reduction in behavioral or neural correlates of executive control compared to the less aggressive participants. Our results question a strong relationship between aggression and executive functions at least for healthy, high-functioning people
Effects of SUSY-QCD in hadronic Higgs production at next-to-next-to-leading order
An estimate of the NNLO supersymmetric QCD effects for Higgs production at
hadron colliders is given. Assuming an effective gluon-Higgs interaction, these
corrections enter only in terms of process-independent, factorizable terms. We
argue that the current knowledge of these terms up to NLO is sufficient to
derive the NNLO hadronic cross section within the limitations of the standard
theoretical uncertainties arising mainly from renormalization and factorization
scale variations. The SUSY contributions are small with respect to the QCD
effects, which means that the NNLO corrections to Higgs production are very
similar in the Standard Model and the MSSM.Comment: LaTeX, 5 pages, 3 embedded PostScript figure
Next-to-Next-to-Leading Order Higgs Production at Hadron Colliders
The Higgs boson production cross section at pp and p\bar{p} colliders is
calculated in QCD at next-to-next-to-leading order (NNLO). We find that the
perturbative expansion of the production cross section is well behaved and that
scale dependence is reduced relative to the NLO result. These findings give us
confidence in the reliability of the prediction. We also report an error in the
NNLO correction to Drell-Yan production.Comment: 5 pages, 4 figures, minor change
Robustly estimating the flow direction of information in complex physical systems
We propose a new measure to estimate the direction of information flux in
multivariate time series from complex systems. This measure, based on the slope
of the phase spectrum (Phase Slope Index) has invariance properties that are
important for applications in real physical or biological systems: (a) it is
strictly insensitive to mixtures of arbitrary independent sources, (b) it gives
meaningful results even if the phase spectrum is not linear, and (c) it
properly weights contributions from different frequencies. Simulations of a
class of coupled multivariate random data show that for truly unidirectional
information flow without additional noise contamination our measure detects the
correct direction as good as the standard Granger causality. For random
mixtures of independent sources Granger Causality erroneously yields highly
significant results whereas our measure correctly becomes non-significant. An
application of our novel method to EEG data (88 subjects in eyes-closed
condition) reveals a strikingly clear front-to-back information flow in the
vast majority of subjects and thus contributes to a better understanding of
information processing in the brain.Comment: 5 pages, 4 figure
Dynamic and thermodynamic properties of the generalised diamond chain model for azurite
The natural mineral azurite Cu3(CO3)2(OH)2 is an interesting spin-1/2 quantum
antiferromagnet. Recently, a generalised diamond chain model has been
established as a good description of the magnetic properties of azurite with
parameters placing it in a highly frustrated parameter regime. Here we explore
further properties of this model for azurite. First, we determine the inelastic
neutron scattering spectrum in the absence of a magnetic field and find good
agreement with experiments, thus lending further support to the model.
Furthermore, we present numerical data for the magnetocaloric effect and
predict that strong cooling should be observed during adiabatic
(de)magnetisation of azurite in magnetic fields slightly above 30T. Finally,
the presence of a dominant dimer interaction in azurite suggests the use of
effective Hamiltonians for an effective low-energy description and we propose
that such an approach may be useful to fully account for the three-dimensional
coupling geometry.Comment: 19 pages, 6 figures; to appear in: J. Phys.: Condens. Matter (special
issue on geometrically frustrated magnetism
Soft and virtual corrections to pp -> H + X at NNLO
The contributions of virtual corrections and soft gluon emission to the
inclusive Higgs production cross section pp -> H + X are computed at
next-to-next-to-leading order in the heavy top quark limit. We show that this
part of the total cross section is well behaved in the sense of perturbative
convergence, with the NNLO corrections amounting to an enhancement of the NLO
cross section by \sim 5% for LHC and 10-20% for the Tevatron. We compare our
results with an existing estimate of the full NNLO effects and argue that an
analytic evaluation of the hard scattering contributions is needed.Comment: 16 pages, 7 figures, 16 ps files embedded with epsf. Minor
modifications: references and note added, results unchange
Jet-veto in bottom-quark induced Higgs production at next-to-next-to-leading order
We present results for associated Higgs+n-jet production in bottom quark
annihilation, for n=0 and n>=1 at NNLO and NLO accuracy, respectively. We
consider both the cases with and without b-tagging. Numerical results are
presented for parameters relevant for experiments at the LHC.Comment: 27 pages, 13 figures, 8 table
Top-mass effects in differential Higgs production through gluon fusion at order \alpha_s^4
Effects from a finite top quark mass on differential distributions in the
Higgs+jet production cross section through gluon fusion are studied at
next-to-leading order in the strong coupling, i.e. . Terms
formally subleading in are calculated, and their influence on the
transverse momentum and rapidity distribution of the Higgs boson are evaluated.
We find that, for the differential K-factor, the heavy-top limit is valid at
the 2-3% level as long as the transverse momentum of the Higgs remains below
about 150 GeV.Comment: 21 pages, 12 figure
One-Year Analysis of the Prospective Multicenter SENTRY Clinical Trial: Safety and Effectiveness of the Novate Sentry Bioconvertible Inferior Vena Cava Filter
Purpose
To prospectively assess the Sentry bioconvertible inferior vena cava (IVC) filter in patients requiring temporary protection against pulmonary embolism (PE).
Materials and Methods
At 23 sites, 129 patients with documented deep vein thrombosis (DVT) or PE, or at temporary risk of developing DVT or PE, unable to use anticoagulation were enrolled. The primary end point was clinical success, including successful filter deployment, freedom from new symptomatic PE through 60 days before filter bioconversion, and 6-month freedom from filter-related complications. Patients were monitored by means of radiography, computerized tomography (CT), and CT venography to assess filtering configuration through 60 days, filter bioconversion, and incidence of PE and filter-related complications through 12 months.
Results
Clinical success was achieved in 111 of 114 evaluable patients (97.4%, 95% confidence interval [CI] 92.5%â99.1%). The rate of freedom from new symptomatic PE through 60 days was 100% (n = 129, 95% CI 97.1%â100.0%), and there were no cases of PE through 12 months for either therapeutic or prophylactic indications. Two patients (1.6%) developed symptomatic caval thrombosis during the first month; neither experienced recurrence after successful interventions. There was no filter tilting, migration, embolization, fracture, or caval perforation by the filter, and no filter-related death through 12 months. Filter bioconversion was successful for 95.7% (110/115) at 6 months and for 96.4% (106/110) at 12 months.
Conclusions
The Sentry IVC filter provided safe and effective protection against PE, with a high rate of intended bioconversion and a low rate of device-related complications, through 12 months of imaging-intense follow-up
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