501 research outputs found
Novel features of dissociation in matter
We make a detailed study of the effect that the recently predicted
modification of the in-medium masses of charmed mesons would have on
dissociation on pion and -meson comovers in relativistic heavy ion
collisions. We find a substantial dependence of the absorption rates
on the density and temperature of the nuclear matter. This suggests that a
quantitative analysis of dissociation in nucleus nucleus collisions
should include the effects of the modification of meson masses in dense matter.Comment: 7 pages, espcrc2, including 5 ps-figures, to be pub. in Phys. Lett.
Inverse Slope Systematics in High-Energy p+p and Au+Au Reactions
We employ the Monte-Carlo PYTHIA to calculate the transverse mass spectra of
various hadrons and their inverse slopes T* at m_T-m=1.5-2 GeV in p+p reactions
at sqrt(s)=200 GeV. Due to (multiple) minijet production T* increases as a
function of the hadron mass. Moreover, the T*(m) systematics has a
``discontinuity'' at the charm threshold, i.e. the inverse slope of D-mesons is
much higher than that of non-charmed hadrons and even of the heavier Lambda_C
baryon. The experimental observation of this characteristic behaviour in Au+Au
collisions would indicate the absence of c-quark rescattering. In contrast, the
assumption of thermalized partons and hydrodynamical evolution would lead to a
smoothly increasing T*(m), without discontinuity at the charm threshold. The
degree of collective transverse flow, indicated by the slope of the T*(m)
systematics, depends strongly on whether kinetic equilibrium is maintained for
some time after hadronization or not.Comment: 14 pages, 2 figures, REVTEX; mistake in plot of c-quark
mt-distribution corrected, some references adde
A novel BRCA2 gene mutation, 4081 insA, in a Finnish breast/ovarian cancer family associated with favourable clinical course
Hydrodynamical assessment of 200 AGeV collisions
We are analyzing the hydrodynamics of 200 A GeV S+S collisions using a new
approach which tries to quantify the uncertainties arising from the specific
implementation of the hydrodynamical model. Based on a previous
phenomenological analysis we use the global hydrodynamics model to show that
the amount of initial flow, or initial energy density, cannot be determined
from the hadronic momentum spectra. We additionally find that almost always a
sizeable transverse flow deve- lops, which causes the system to freeze out,
thereby limiting the flow velocity in itself. This freeze-out dominance in turn
makes a distinction between a plasma and a hadron resonance gas equation of
state very difficult, whereas a pure pion gas can easily be ruled out from
present data. To complete the picture we also analyze particle multiplicity
data, which suggest that chemical equilibrium is not reached with respect to
the strange particles. However, the over- population of pions seems to be at
most moderate, with a pion chemical potential far away from the Bose
divergence.Comment: 19 pages, 11 figs in separate uuencoded file, for LateX, epsf.tex,
dvips, TPR-94-5 and BNL-(no number yet
Evaluation of minimal fracture liaison service resource : costs and survival in secondary fracture prevention-a prospective one-year study in South-Finland
Background Fracture liaison service (FLS) is a secondary prevention model for identification of patients at risk for fragility fractures. Aims This study was conducted to evaluate the number and costs of secondary prevention of low-energy fractures in the city of Kouvola in Finland. Methods Women aged >= 45 years and men >= 60 years treated in the emergency department with a low-energy fracture were identified. Laboratory testing, BMI, and DXA scans were performed. Fracture Risk Assessment Tool was used. The direct FLS costs were calculated. Survival was analyzed using univariate and multivariate analysis and the life-table method. Results 525 patients with 570 fractures were identified. The mean age of women was 73.8 years and of men 75.9 years. Most patients sustained wrist (31%), hip (21%) or proximal humerus (12%) fractures. 41.5% of the patients had osteoporosis according to DXA scans. 62% of patients used calcium and vitamin D daily and 38% started anti-osteoporotic medication. Protective factors for survival were: age <80 years, female sex, and S-25OHD concentration of 50-119 nmol/L. Excess mortality was highest among patients with a fracture of the femur. The total annual direct costs of FLS were 1.3% of the costs of all fractures. Discussion Many low-energy fracture types were associated with excess mortality. The use of anti-osteoporotic medication was not optimal. Conclusions FLS increased the catchment of low-energy fracture patients and was inexpensive. However, identification, evaluation and post-fracture assessment of patients should be expedited. Rehabilitation of hip fracture patients needs to be improved.Peer reviewe
Magneto-optical Kerr effect susceptometer for the analysis of magnetic domain wall dynamics
Domain wall dynamics in thin magnetic films with perpendicular and in-plane anisotropy is studied using a novel magneto-optical Kerr effect susceptometry method. The method allows for measurements of domain wall motion under ac field excitation and the analysis of dynamic modes as a function of driving frequency and magnetic field amplitude. Domain wall dynamics in the perpendicular anisotropy system, a Co/Pt multilayer, is characterized by thermally activated creep motion. For this dynamic mode, a polydispersivity exponent of ÎČ = 0.50 ± 0.03 is derived at small excitation energy, which is in excellent agreement with theoretical models. The dynamics of the other system, a Co wire with transverse uniaxial anisotropy, is dominated by viscous slide motion in a regular magnetic stripe pattern. Analytical expressions are derived for this magnetic configuration and by using these expressions, accurate values for the depinning field and the domain wall mobility are extracted from the susceptibility measurements.Peer reviewe
Guiding and reflecting light by boundary material
We study effects of finite height and surrounding material on photonic
crystal slabs of one- and two-dimensional photonic crystals with a
pseudo-spectral method and finite difference time domain simulation methods.
The band gap is shown to be strongly modified by the boundary material. As an
application we suggest reflection and guiding of light by patterning the
material on top/below the slab.Comment: 12 pages, 7 figure
Rapidity Distributions of Dileptons from a Hadronizing Quark-Gluon Plasma
It has been predicted that dilepton production may be used as a quark-gluon
plasma probe. We calculate the rapidity distributions of thermal dileptons
produced by an evolving quark-gluon plasma assuming a longitudinal scaling
expansion with initial conditions locally determined from the hadronic rapidity
density. These distributions are compared with Drell-Yan production and
semileptonic charm decays at invariant mass , 4, and 6 GeV.Comment: 17 pages (standard LaTeX), 6 figures (available as topdraw files or
printed versions upon request), GSI-93-6
Thermal phenomenology of hadrons from 200 AGeV S+S collisions
We develop a complete and consistent description for the hadron spectra from
heavy ion collisions in terms of a few collective variables, in particular
temperature, longitudinal and transverse flow. To achieve a meaningful
comparison with presently available data, we also include the resonance decays
into our picture. To disentangle the influences of transverse flow and
resonance decays in the -spectra, we analyse in detail the shape of the
-spectra.Comment: 31 pages, 13 figs in seperate uuencoded file, for LaTeX, epsf.sty and
dvips, TPR-93-16 and BNL-(no number yet
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