3,472 research outputs found
The karabus affair speaks to larger issues for american academic and medical centers.
Finally, on March 12, 2013, a major American newspaper, The Wall Street Journal, reported on the plight of Dr. Cyril Karabus (1,2). Dr. Karabus is the 78 year old pediatric oncologist from Claremont, Capetown, South Africa who is well known as the retired head of the Oncology and Hematology Unit of the Red Cross Children’s Hospital, University of Cape Town, as well as for his devoted service to poor children in the apartheid era. In 2002, he cared for a three-year old Yemeni girl with acute myelogenous leukemia during a locum tenens in the United Arab Emirates (UAE)
Diffractive Dissociation and Eikonalization in High Energy pp and p Collisions
We show that eikonal corrections imposed on diffraction dissociation
processes calculated in the triple Regge limit, produce a radical change in the
energy dependence of the predicted cross section. The induced correction is
shown to be in general agreement with the new experimental data measured at the
Tevatron.Comment: 11 pages LATEX, ( two figures not included obtainable from authors)
(TAUP 2066-93 and FERMILAB PUB 93/ T
Spin- generalization of fractional exclusion statistics
We study fractional exclusion statistics for quantum systems with SU(2)
symmetry (arbitrary spin ), by generalizing the thermodynamic equations with
squeezed strings proposed by Ha and Haldane. The bare hole distributions as
well as the statistical interaction defined by an infinite-dimensional matrix
specify the universality class. It is shown that the system is described by the
level- WZW model and has a close relationship to non-abelian fractional
quantum Hall states. As a low-energy effective theory, the sector of {\it
massless} Z parafermions is extracted, whose statistical interaction is
given by a finite-dimensional matrix.Comment: 11pages, REVTE
Constraining N2O emissions since 1940 using firn air isotope measurements in both hemispheres
N2O is currently the third most important anthropogenic greenhouse gas in terms of radiative forcing and its atmospheric mole fraction is rising steadily. To quantify the growth rate and its causes over the past decades, we performed a multi-site reconstruction of the atmospheric N2O mole fraction and isotopic composition using new and previously published firn air data collected from Greenland and Antarctica in combination with a firn diffusion and densification model. The multi-site reconstruction showed that while the global mean N2O mole fraction increased from (290±1)nmolmol-1 in 1940 to (322±1)nmolmol-1 in 2008, the isotopic composition of atmospheric N2O decreased by (-2.2±0.2)% for δ15Nav, (-1.0±0.3)% for δ18O, (-1.3±0.6)% for δ15Nα, and (-2.8±0.6)% for δ15Nβ over the same period. The detailed temporal evolution of the mole fraction and isotopic composition derived from the firn air model was then used in a two-box atmospheric model (comprising a stratospheric box and a tropospheric box) to infer changes in the isotopic source signature over time. The precise value of the source strength depends on the choice of the N2O lifetime, which we choose to fix at 123 years. The average isotopic composition over the investigated period is δ15Nav Combining double low line (-7.6±0.8)% (vs. air-N2), δ18O Combining double low line (32.2±0.2)% (vs. Vienna Standard Mean Ocean Water-VSMOW) for δ18O, δ15Nα Combining double low line (-3.0±1.9)% and δ15Nβ Combining double low line (-11.7±2.3)%. δ15Nav, and δ15Nβ show some temporal variability, while for the other signatures the error bars of the reconstruction are too large to retrieve reliable temporal changes. Possible processes that may explain trends in 15N are discussed. The 15N site preference (Combining double low line δ15Nα-δ15Nβ) provides evidence of a shift in emissions from denitrification to nitrification, although the uncertainty envelopes are large
Measuring Parton Densities in the Pomeron
We present a program to measure the parton densities in the pomeron using
diffractive deep inelastic scattering and diffractive photoproduction, and to
test the resulting parton densities by applying them to other processes such as
the diffractive production of jets in hadron-hadron collisions. Since QCD
factorization has been predicted NOT to apply to hard diffractive scattering,
this program of fitting and using parton densities might be expected to fail.
Its success or failure will provide useful information on the space-time
structure of the pomeron.Comment: Contains revisions based on Phys. Rev. D referee comments. RevTeX
version 3, epsf, 31 pages. Uuencoded compressed postscript figures appended.
Uncompressed postscript files available at
ftp://ftp.phys.psu.edu/pub/preprint/psuth136
Stochastic Gravity: Theory and Applications
Whereas semiclassical gravity is based on the semiclassical Einstein equation
with sources given by the expectation value of the stress-energy tensor of
quantum fields, stochastic semiclassical gravity is based on the
Einstein-Langevin equation, which has in addition sources due to the noise
kernel. In the first part, we describe the fundamentals of this new theory via
two approaches: the axiomatic and the functional. In the second part, we
describe three applications of stochastic gravity theory. First, we consider
metric perturbations in a Minkowski spacetime, compute the two-point
correlation functions of these perturbations and prove that Minkowski spacetime
is a stable solution of semiclassical gravity. Second, we discuss structure
formation from the stochastic gravity viewpoint. Third, we discuss the
backreaction of Hawking radiation in the gravitational background of a black
hole and describe the metric fluctuations near the event horizon of an
evaporating black holeComment: 100 pages, no figures; an update of the 2003 review in Living Reviews
in Relativity gr-qc/0307032 ; it includes new sections on the Validity of
Semiclassical Gravity, the Stability of Minkowski Spacetime, and the Metric
Fluctuations of an Evaporating Black Hol
The Fitness Cost of Antibiotic Resistance in Streptococcus pneumoniae: Insight from the Field
Laboratory studies have suggested that antibiotic resistance may result in decreased fitness in the bacteria that harbor it. Observational studies have supported this, but due to ethical and practical considerations, it is rare to have experimental control over antibiotic prescription rates.We analyze data from a 54-month longitudinal trial that monitored pneumococcal drug resistance during and after biannual mass distribution of azithromycin for the elimination of the blinding eye disease, trachoma. Prescription of azithromycin and antibiotics that can create cross-resistance to it is rare in this part of the world. As a result, we were able to follow trends in resistance with minimal influence from unmeasured antibiotic use. Using these data, we fit a probabilistic disease transmission model that included two resistant strains, corresponding to the two dominant modes of resistance to macrolide antibiotics. We estimated the relative fitness of these two strains to be 0.86 (95% CI 0.80 to 0.90), and 0.88 (95% CI 0.82 to 0.93), relative to antibiotic-sensitive strains. We then used these estimates to predict that, within 5 years of the last antibiotic treatment, there would be a 95% chance of elimination of macrolide resistance by intra-species competition alone.Although it is quite possible that the fitness cost of macrolide resistance is sufficient to ensure its eventual elimination in the absence of antibiotic selection, this process takes time, and prevention is likely the best policy in the fight against resistance
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS
The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured
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