328 research outputs found
Active surveillance for prostate cancer: Is it ready for primetime in the Caribbean?
Objective: In this paper we discuss the strategy of active surveillance (AS) as a whole followed by the implications of its use in the Caribbean.Methods: The literature was reviewed with a view to establishing the merits of AS and to identify potential pitfalls in the application of AS among a primarily black population.Results: Active surveillance (AS) has emerged as a viable treatment strategy aimed at reducing overtreat-ment of indolent disease. However, there have been concerns raised over the applicability of AS among men of African descent. Black men are at higher risk of aggressive disease and data are emerging which suggestoutcomes may not parallel those of their white counterparts. Recent advances such as multiparametric MRI and genetic testing have the potential to guide decision making in these men.Conclusion: Active surveillance should not be universally rejected in black men and perhaps further study is needed to determine race-specific recommendations. Until then, discussion with the patient should reflect the potential pitfalls for black men on active surveillance.Keywords: Active surveillance; Caribbean; Africa
Thomas-Fermi-Poisson theory of screening for latterally confined and unconfined two-dimensional electron systems in strong magnetic fields
We examine within the self-consistent Thomas-Fermi-Poisson approach the
low-temperature screening properties of a two-dimensional electron gas (2DEG)
subjected to strong perpendicular magnetic fields. Numerical results for the
unconfined 2DEG are compared with those for a simplified Hall bar geometry
realized by two different confinement models. It is shown that in the strongly
non-linear screening limit of zero temperature the total variation of the
screened potential is related by simple analytical expressions to the amplitude
of an applied harmonic modulation potential and to the strength of the magnetic
field.Comment: 12 pages, 12 figure
Nonlinear screening and percolative transition in a two-dimensional electron liquid
A novel variational method is proposed for calculating the percolation
threshold, the real-space structure, and the thermodynamical compressibility of
a disordered two-dimensional electron liquid. Its high accuracy is verified
against prior numerical results and newly derived exact asymptotics. The
inverse compressibility is shown to have a strongly asymmetric minimum at a
density that is approximately the triple of the percolation threshold. This
implies that the experimentally observed metal-insulator transition takes place
well before the percolation point is reached.Comment: 4 pages, 2 figures. (v2) minor changes (v3) reference added (v4) few
more references adde
The Bogoliubov Theory of a BEC in Particle Representation
In the number-conserving Bogoliubov theory of BEC the Bogoliubov
transformation between quasiparticles and particles is nonlinear. We invert
this nonlinear transformation and give general expression for eigenstates of
the Bogoliubov Hamiltonian in particle representation. The particle
representation unveils structure of a condensate multiparticle wavefunction. We
give several examples to illustrate the general formalism.Comment: 10 pages, 9 figures, version accepted for publication in Phys. Rev.
Relaxation rates and collision integrals for Bose-Einstein condensates
Near equilibrium, the rate of relaxation to equilibrium and the transport
properties of excitations (bogolons) in a dilute Bose-Einstein condensate (BEC)
are determined by three collision integrals, ,
, and . All three collision integrals
conserve momentum and energy during bogolon collisions, but only conserves bogolon number. Previous works have considered the
contribution of only two collision integrals, and . In this work, we show that the third collision integral makes a significant contribution to the bogolon number
relaxation rate and needs to be retained when computing relaxation properties
of the BEC. We provide values of relaxation rates in a form that can be applied
to a variety of dilute Bose-Einstein condensates.Comment: 18 pages, 4 figures, accepted by Journal of Low Temperature Physics
7/201
Atrial natriuretic factor
The discovery of the first well-defined natriuretic hormone, the Atrial Natriuretic Factor (ANF), has prompted research on its impact on volume regulation in health and disease. The natriuretic, diuretic, and smooth muscle-relaxing properties suggest an important role of this novel hormone in pathophysiological states with sodium or volume retention, such as congestive heart failure or cirrhosis of the liver. Investigations on the implications of ANF in liver disease have been performed for little more than 1 year, and results are still controversial in many respects. At present, it seems very likely that there is no absolute deficiency of plasma ANF in patients with cirrhosis. Moreover, elevated plasma levels in cirrhotics with ascites have been reported by several groups. However, as yet, a molecular characterization of this increased immunoreactivity is still lacking. There is disagreement on the reduced release of and renal response to ANF in subgroups of cirrhotics; however, stimulus-response-coupling might be impaired. Further studies are needed to elucidate the pathophysiological implications and therapeutical potential of ANF in patients with chronic liver disease
Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV
We present a search for the production of neutral Higgs bosons decaying into
tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The
data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by
the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the
95% C.L. on the product of production cross section and branching ratio for a
scalar resonance decaying into tautau pairs, and we then interpret these limits
as limits on the production of Higgs bosons in the minimal supersymmetric
standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL
Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV
We present the first measurement of the inclusive three-jet differential
cross section as a function of the invariant mass of the three jets with the
largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96
TeV. The measurement is made in different rapidity regions and for different
jet transverse momentum requirements and is based on a data set corresponding
to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at
the Fermilab Tevatron Collider. The results are used to test the three-jet
matrix elements in perturbative QCD calculations at next-to-leading order in
the strong coupling constant. The data allow discrimination between
parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected
chi2 values for NNPD
Measurements of inclusive W+jets production rates as a function of jet transverse momentum in ppbar collisions at sqrt{s}=1.96 TeV
This Letter describes measurements of inclusive W (--> e nu) + n jet cross
sections (n = 1-4), presented as total inclusive cross sections and
differentially in the nth jet transverse momentum. The measurements are made
using data corresponding to an integrated luminosity of 4.2 fb-1 collected by
the D0 detector at the Fermilab Tevatron Collider, and achieve considerably
smaller uncertainties on W +jets production cross sections than previous
measurements. The measurements are compared to next-to-leading order
perturbative QCD (pQCD) calculations in the n =1-3 jet multiplicity bins and to
leading order pQCD calculations in the 4-jet bin. The measurements are
generally in agreement with pQCD predictions, although certain regions of phase
space are identified where the calculations could be improved
Search for single vector-like quarks in ppbar collisions at sqrt(s) = 1.96 TeV
We present a search for hypothetical vector-like quarks in ppbar collisions
at sqrt(s) = 1.96 TeV. The data were collected by the D0 detector at the
Fermilab Tevatron Collider and correspond to an integrated luminosity of 5.4
fb^(-1). We select events with a final state composed of a W or Z boson and a
jet consistent with a heavy object decay. We observe no significant excess in
comparison to the background prediction and set limits on production cross
sections for vector-like quarks decaying to W+jet and Z+jet. These are the most
stringent mass limits for electroweak single vector-like quark production at
hadron colliders.Comment: submitted to Phys. Rev. Let
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