1,308 research outputs found
The effect of nifedipine on fetal umbilical Doppler waveforms in pregnancies by hypertension
The effect of nifedipine 5 mg administered sublingually to pregnant hypertensive patients was examined in a randomised controlled double-blind study. The effect on maternal blood pressure and the fetal umbilical artery Doppler waveform was studied for 30 minutes before and 30 minutes after administration of the drug or placebo. This dose resulted in a significant drop in maternal blood pressure 30 minutes after administration and did not result in a significant change in the Doppler umbilical artery waveform (in fetuses with normal waveforms) when compared with a control group
Charmonium Suppression by Comover Scattering in Pb+Pb Collisions
The first reports of and production from experiment NA50 at
the CERN SPS are compared to predictions based on a hadronic model of
charmonium suppression. Data on centrality dependence and total cross sections
are in good accord with these predictions.Comment: 9 pages, latex, 6 figures, epsf, figure added and text modified to
clarify result
Open and Hidden Charm Production in Heavy Ion Collisions at Ultrarelativistic Energies
We consider the production of the open charm and J/psi mesons in heavy ion
collisions at BNL RHIC. We discuss several recently developed pictures for
J/psi production and argue that a measurement at RHIC energies is crucial for
disentangling these different descriptions.Comment: 19 pages, Latex, 5 PS-figures. v3: Fig.6 is adde
Interpretations of suppression
We review the two main interpretations of suppression proposed in
the literature. The phase transition (or deconfining) scenario assumes that
below some critical value of the local energy density (or of some other
geometrical quantity which depends both on the colliding systems and on the
centrality of the collision), there is only nuclear absorption. Above this
critical value the absorptive cross-section is taken to be infinite, i.e. no
can survive in this hot region. In the hadronic scenario the
dissociates due both to nuclear absorption and to its interactions with
co-moving hadrons produced in the collision. No discontinuity exists in
physical observables. We show that an equally good description of the present
data is possible in either scenario.Comment: 12 pages, LaTeX, uses epsfig and ioplppt; review talk given by A.
Capella at the International Symposium on Strangness in Quark Matter,
Santorini (Greece), April 1997; Figs. 1 and 2 not available but can be found
in Refs. 13 and 6 respectivel
Open Charm Enhancement in Pb+Pb Collisions at SPS
The statistical coalescence model for the production of open and hidden charm
is considered within the canonical ensemble formulation. The data for the
J/\psi multiplicity in Pb+Pb collisions at 158 A GeV are used for the model
prediction of the open charm yield. We find a strong enhancement of the open
charm production, by a factor of about 2--4, over the standard hard-collision
model extrapolation from nucleon-nucleon to nucleus-nucleus collisions. A
possible mechanism of the open charm enhancement in A+A collisions at the SPS
energies is proposed.Comment: 4 pages, Late
J/\Psi production, polarization and Color Fluctuations
The hard contributions to the heavy quarkonium-nucleon cross sections are
calculated based on the QCD factorization theorem and the nonrelativistic
quarkonium model. We evaluate the nonperturbative part of these cross sections
which dominates at GeV at the Cern Super Proton
Synchrotron (SPS) and becomes a correction at TeV at
the CERN Large Hadron Collider (LHC). \J production at the CERN SPS is well
described by hard QCD, when the larger absorption cross sections of the
states predicted by QCD are taken into account. We predict an -dependent
polarization of the states. The expansion of small wave packets is
discussed.Comment: 13 pages REVTEX, 1 table, 2 PostScript, corrected some typo
Correlations in Nuclear Arrhenius-Type Plots
Arrhenius-type plots for multifragmentation process, defined as the
transverse energy dependence of the single-fragment emission-probability,
-ln(p_{b}) vs 1/sqrt(E_{t}), have been studied by examining the relationship of
the parameters p_{b} and E_{t} to the intermediate-mass fragment multiplicity
. The linearity of these plots reflects the correlation of the fragment
multiplicity with the transverse energy. These plots may not provide thermal
scaling information about fragment production as previously suggested.Comment: 12 pages, Latex, 3 Postscript figures include
Inhomogeneous isospin distribution in the reactions of 28Si + 112Sn and 124Sn at 30 and 50 MeV/nucleon
We have created quasiprojectiles of varying isospin via peripheral reactions
of 28Si + 112Sn and 124Sn at 30 and 50 MeV/nucleon. The quasiprojectiles have
been reconstructed from completely isotopically identified fragments. The
difference in N/Z of the reconstructed quasiprojectiles allows the
investigation of the disassembly as a function of the isospin of the
fragmenting system. The isobaric yield ratio 3H/3He depends strongly on N/Z
ratio of quasiprojectiles. The dependences of mean fragment multiplicity and
mean N/Z ratio of the fragments on N/Z ratio of the quasiprojectile are
different for light charged particles and intermediate mass fragments.
Observation of a different N/Z ratio of light charged particles and
intermediate mass fragments is consistent with an inhomogeneous distribution of
isospin in the fragmenting system.Comment: 5 pages, 4 Postscript figures, RevTe
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