6,826 research outputs found
Enhancement of low- kaons in AGS heavy-ion collisions
In the relativistic transport model, we show that the recently observed
enhancement of low- kaons ( and ) in Si+Pb collisions at AGS can
be explained if a density isomer is introduced in the nuclear
equation-of-state.Comment: 12 pages, RevTex, 6 figs on request to [email protected]
Findings from retinal optical coherence tomography in a large cohort, UK Biobank
Background: UK Biobank is a large prospective multi-center community-based study, which included macular optical coherence tomography (OCT) of 67,321 people. OCT is a mainstay of ophthalmic imaging and is a potential screening test for dementia. Aim of research: Cross-sectional analysis examined retinal layers, to determine the range of findings in normal individuals, as well as describe associations with demographic and physiologic variation. Longitudinal analysis assessed associations with not only current cognitive function, but future cognitive decline. Results: All layers showed progressive thinning with older age. As compared to white people, black ethnicity was associated with significantly thicker retinal pigment epithelium (RPE) (+3.35 μm; p<0.001), but thinner photoreceptor inner segment-outer segment (IS-OS), ganglion cell layer-inner plexiform layer complex (GCL-IPL), and macular retinal nerve fibre layer (mRNFL) (-3.76 μm, -4.29 μm, and -3.97 μm, respectively; p<0.001). Higher intraocular pressure was associated with thinner RPE (- 0.04 μm per mmHg, p<0.001), but was not significant at GCL-IPL or mRNFL. Higher body mass index was associated with thinner photoreceptor IS-OS (-0.12 μm per kg/m2, p<0.001). Asian and Chinese ethnicity, refractive error, height, sex, smoking, and blood pressure showed mixed results. Socioeconomic deprivation, educational levels, and cognitive function were examined for GCL-IPL and mRNFL. Socioeconomic deprivation was associated with significantly thinner GCL-IPL, but was not significant at mRNFL. In contrast, lower education was significantly associated with thinner mRNFL but was not significant at GCL-IPL. Thinner mRNFL was associated with worse baseline cognitive performance. Follow-up cognitive tests were performed for 1251 participants. Participants with mRNFL thickness in the two thinnest quintiles were almost twice as likely to have at least one test score worse at follow-up cognitive testing (quintile 1: odds ratio (OR) 1.92, 95% CI: 1.29, 2.85, p<0.001, quintile 2: OR: 2.08, 95% CI: 1.40, 3.08, P< 0.001). While there were some associations between GCL-IPL and baseline cognitive function, no association was detected for risk of future cognitive decline. Significance: Retinal thickness is variable and dynamic. This work will inform interpretation of both past and future research, as physiologic and demographic variation is associated with thickness of each layer. Of note, I show an association between IOP and RPE but not mRNFL. Further, thinner mRNFL is associated with greater likelihood of cognitive decline in the future. These observations have implications for future research, as well as prevention and treatment of dementia
Phi Meson Production in Heavy-Ion Collisions at SIS Energies
Phi meson production in heavy-ion collisions at SIS/GSI energies (
GeV/nucleon) is studied in the relativistic transport model. We include
contributions from baryon-baryon, pion-baryon, and kaon-antikaon collisions.
The cross sections for the first two processes are obtained in an
one-boson-exchange model, while that for the last process is taken to be of
Breit-Wigner form through the phi meson resonance. The dominant contribution to
phi meson production in heavy ion collisions at these energies is found to come
from secondary pion-nucleon collisions. Effects due to medium modifications of
kaon masses are also studied and are found to reduce the phi meson yield by
about a factor of two, mainly because of increased phi decay width as a result
of dropping kaon-antikaon masses. In this case, the ratio is about
4%, which is a factor of 2-3 below preliminary experimental data from the FOPI
collaboration at GSI. Including also the reduction of phi meson mass in medium
increases this ratio to about 8%, which is then in reasonable agreement with
the data.Comment: 46 pages, including 21 postscript figure
Can dileptons reveal the in-medium properties of vector mesons?
Dilepton production from both pion-pion and kaon-antikaon annihilation in
heavy-ion collisions is studied using the relativistic transport model. The
formation of a rho meson from pion-pion annihilation and a phi meson from
kaon-antikaon annihilation, their propagation in the medium, and their decay
into dileptons are explicitly treated. Including the medium modifications of
the masses and widths of vector mesons as predicted by the QCD sum-rule
calculations, we study their effects on the dilepton invariant mass spectra
from heavy-ion collisions at SIS/GSI energies.Comment: 22 pages, 11 figures available upon request to [email protected]
Role of the Coulomb interaction in the flow and the azimuthal distribution of kaons from heavy ion reactions
Coulomb final-state interaction of positive charged kaons in heavy ion
reactions and its impact on the kaon transverse flow and the kaon azimuthal
distribution are investigated within the framework of QMD (Quantum Molecular
Dynamics) model. The Coulomb interaction is found to tend to draw the flow of
kaons away from that of nucleons and lead to a more isotropic azimuthal
distribution of kaons in the target rapidity region. The recent FOPI data have
been analyzed by taking into accout both the Coulomb interaction and a kaon
in-medium potential of the strong interaction. It is found that both the
calculated kaon flows with only the Coulomb interaction and with both the
Coulomb interaction and the strong potential agree within the error bars with
the data. The kaon azimuthal distribution exhibits asymmetries of similar
magnitude in both theoretical approaches. This means, the inclusion of the
Coulomb potential makes it more difficult to extract information of the kaon
mean field potential in nuclear matter from the kaon flow and azimuthal
distribution data.Comment: 14 pages Latex, 4 PS-file
Kaon versus Antikaon Production at SIS Energies
We analyse the production and propagation of kaons and antikaons in Ni + Ni
reactions from 0.8--1.85 GeV/u within a coupled channel transport approach
including the channels as well as and for
the antikaon absorption. Whereas the experimental spectra can be
reproduced without introducing any selfenergies for the mesons in Ni + Ni
collisions from 0.8 to 1.8 GeV/u, the yield is underestimated by a factor
of 5--7 at 1.66 and 1.85 GeV/u. However, introducing density dependent antikaon
masses as proposed by Kaplan and Nelson, the antikaon spectra can be reasonably
well described.Comment: 16 pages, LaTeX, plus 12 postscript figures, submitted to Nucl. Phys.
BU10038 as a safe opioid analgesic with fewer side-effects after systemic and intrathecal administration in primates
© 2019 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.Background: The marked increase in mis-use of prescription opioids has greatly affected our society. One potential solution is to develop improved analgesics which have agonist action at both mu opioid peptide (MOP) and nociceptin/orphanin FQ peptide (NOP) receptors. BU10038 is a recently identified bifunctional MOP/NOP partial agonist. The aim of this study was to determine the functional profile of systemic or spinal delivery of BU10038 in primates after acute and chronic administration. Methods: A series of behavioural and physiological assays have been established specifically to reflect the therapeutic (analgesia) and side-effects (abuse potential, respiratory depression, itch, physical dependence, and tolerance) of opioid analgesics in rhesus monkeys. Results: After systemic administration, BU10038 (0.001–0.01 mg kg −1 ) dose-dependently produced long-lasting antinociceptive and antihypersensitive effects. Unlike the MOP agonist oxycodone, BU10038 lacked reinforcing effects (i.e. little or no abuse liability), and BU10038 did not compromise the physiological functions of primates including respiration, cardiovascular activities, and body temperature at antinociceptive doses and a 10–30-fold higher dose (0.01–0.1 mg kg −1 ). After intrathecal administration, BU10038 (3 μg) exerted morphine-comparable antinociception and antihypersensitivity without itch scratching responses. Unlike morphine, BU10038 did not cause the development of physical dependence and tolerance after repeated and chronic administration. Conclusions: These in vivo findings demonstrate the translational potential of bifunctional MOP/NOP receptor agonists such as BU10038 as a safe, non-addictive analgesic with fewer side-effects in primates. This study strongly supports that bifunctional MOP/NOP agonists may provide improved analgesics and an alternative solution for the ongoing prescription opioid crisis.Peer reviewedFinal Published versio
Relativistic Transport Approach for Nucleus-Nucleus Collisions from SIS to SPS Energies
We formulate a covariant transport approach for high energy nucleus-nucleus
collisions where the real part of the nucleon selfenergies is fitted to nuclear
matter properties which are evaluated on the basis of a NJL-type Lagrangian for
the quark degrees of freedom. The parameters of the quark-model Lagrangian are
fixed by the Gell-Mann, Oakes and Renner relation, the pion- nucleon
-term, the nucleon energy as well as the nuclear binding energy at
saturation density . We find the resulting scalar and vector
selfenergies for nucleons to be well in line with either Dirac-Brueckner
computations for or those from the phenomenological
optical potential when accounting for a swelling of the nucleon at finite
nuclear matter density. The meson-baryon interaction density is modelled to
describe a decrease of the meson mass with baryon density. The imaginary part
of the hadron selfenergies is determined by a string fragmentation model which
accounts for the in-medium mass of hadrons in line with the 'chiral' dynamics
employed. The applicability of the transport approach is demonstrated in
comparison with experimental data from SIS to SPS energies. The enhancement of
the K ratio in A + A collisions compared to p + A reactions at AGS
energies is reproduced within the 'chiral' dynamics. Furthermore, detailed
predictions for the stopping in Pb + Pb collisions at 153 GeV/A are presented.Comment: 1 compressed uuencoded postscript file with 23 figures included, 45
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