302 research outputs found
Similarity and contrasts between thermodynamic properties at the critical point of liquid alkali metals and of electron-hole droplets
The recent experimental study by means of time-resolved luminescence
measurements of an electron-hole liquid (EHL) in diamond by Shimano et al.
[Phys. Rev. Lett. 88 (2002) 057404] prompts us to compare and contrast critical
temperature T_c and critical density n_c relations in liquid alkali metals with
those in electron-hole liquids. The conclusion drawn is that these systems have
similarities with regard to critical properties. In both cases the critical
temperature is related to the cube root of the critical density. The existence
of this relation is traced to Coulomb interactions and to systematic trends in
the dielectric constant of the electron-hole systems. Finally a brief
comparison between the alkalis and EHLs of the critical values for the
compressibility ratio Z_c is also given
Hydrodynamical analysis of symmetric nucleus-nucleus collisions at CERN/SPS energies
We present a coherent theoretical study of ultrarelativistic heavy-ion data
obtained at the CERN/SPS by the NA35/NA49 Collaborations using 3+1-dimensional
relativistic hydrodynamics. We find excellent agreement with the rapidity
spectra of negative hadrons and protons and with the correlation measurements
in two experiments: at 200 and at 160 (preliminary
results). Within our model this implies that for () a
quark-gluon-plasma of initial volume 174 (24 ) with a lifetime 3.4
(1.5 ) was formed. It is found that the Bose-Einstein correlation
measurements do not determine the maximal effective radii of the hadron sources
because of the large contributions from resonance decay at small momenta. Also
within this study we present an NA49 acceptance corrected two-pion
Bose-Einstein correlation function in the invariant variable, .Comment: 21 pages, 11 Postscript figures (1 File, 775654 Bytes, has to be
requested for submission via e.mail from [email protected]
Deconfining Phase Transition as a Matrix Model of Renormalized Polyakov Loops
We discuss how to extract renormalized from bare Polyakov loops in SU(N)
lattice gauge theories at nonzero temperature in four spacetime dimensions.
Single loops in an irreducible representation are multiplicatively renormalized
without mixing, through a renormalization constant which depends upon both
representation and temperature. The values of renormalized loops in the four
lowest representations of SU(3) were measured numerically on small, coarse
lattices. We find that in magnitude, condensates for the sextet and octet loops
are approximately the square of the triplet loop. This agrees with a large
expansion, where factorization implies that the expectation values of loops in
adjoint and higher representations are just powers of fundamental and
anti-fundamental loops. For three colors, numerically the corrections to the
large relations are greatest for the sextet loop, ; these
represent corrections of for N=3. The values of the renormalized
triplet loop can be described by an SU(3) matrix model, with an effective
action dominated by the triplet loop. In several ways, the deconfining phase
transition for N=3 appears to be like that in the matrix model of
Gross and Witten.Comment: 24 pages, 7 figures; v2, 27 pages, 12 figures, extended discussion
for clarity, results unchange
'Education, education, education' : legal, moral and clinical
This article brings together Professor Donald Nicolson's intellectual interest in professional legal ethics and his long-standing involvement with law clinics both as an advisor at the University of Cape Town and Director of the University of Bristol Law Clinic and the University of Strathclyde Law Clinic. In this article he looks at how legal education may help start this process of character development, arguing that the best means is through student involvement in voluntary law clinics. And here he builds upon his recent article which argues for voluntary, community service oriented law clinics over those which emphasise the education of students
Antimetastatic Potential of PAI-1 Specific RNA Aptamers
The serine protease inhibitor plasminogen activator inhibitor-1 (PAI-1) is increased in several cancers, including breast, where it is associated with a poor outcome. Metastatic breast cancer has a dismal prognosis, as evidenced by treatment goals that are no longer curative but are largely palliative in nature. PAI-1 competes with integrins and the urokinase plasminogen activator receptor on the surface of breast cancer cells for binding to vitronectin. This results in the detachment of tumor cells from the extracellular matrix, which is critical to the metastatic process. For this reason, we sought to isolate RNA aptamers that disrupt the interaction between PAI-1 and vitronectin. Through utilization of combinatorial chemistry techniques, aptamers have been selected that bind to PAI-1 with high affinity and specificity. We identified two aptamers, WT-15 and SM-20, that disrupt the interactions between PAI-1 and heparin, as well as PAI-1 and vitronectin, without affecting the antiprotease activity of PAI-1. Furthermore, SM-20 prevented the detachment of breast cancer cells (MDA-MB-231) from vitronectin in the presence of PAI-1, resulting in an increase in cellular adhesion. Therefore, the PAI-1 aptamer SM-20 demonstrates therapeutic potential as an antimetastatic agent and could possibly be used as an adjuvant to traditional chemotherapy for breast cancer.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78126/1/oli.2008.0177.pd
A "critical" climatic evaluation of last interglacial (MIS 5e) records from the Norwegian Sea
Sediment cores from the Norwegian Sea were studied to evaluate interglacial climate conditions of the marine isotope stage 5e (MIS 5e). Using planktic forminiferal assemblages as the core method, a detailed picture of the evolution of surface water conditions was derived. According to our age model, a step-like deglaciation of the Saalian ice sheets is noted between ca. 135 and 124.5 Kya, but the deglaciation shows little response with regard to surface ocean warming. From then on, the rapidly increasing abundance of subpolar forminifers, concomitant with decreasing iceberg indicators, provides evidence for the development of interglacial conditions sensu stricto (5e-ss), a period that lasted for about 9 Ky. As interpreted from the foraminiferal records, and supported by the other proxies, this interval of 5e-ss was in two parts: showing an early warm phase, but with a fresher, i.e., lower salinity, water mass, and a subsequent cooling phase that lasted until ca. 118.5 Kya. After this time, the climatic optimum with the most intense advection of Atlantic surface water masses occurred until ca. 116 Kya. A rapid transition with two notable climatic perturbations is observed subsequently during the glacial inception. Overall, the peak warmth of the last interglacial period occurred relatively late after deglaciation, and at no time did it reach the high warmth level of the early Holocene. This finding must be considered when using the last interglacial situation as an analogue model for enhanced meridional transfer of ocean heat to the Arctic, with the prospect of a future warmer climate
K isomers in No254: Probing single-particle energies and pairing strengths in the heaviest nuclei
We have identified two isomers in No254, built on two- and four-quasiparticle excitations, with quantum numbers KÏ=8- and (14+), as well as a low-energy 2-quasiparticle KÏ=3+ state. The occurrence of isomers establishes that K is a good quantum number and therefore that the nucleus has an axial prolate shape. The 2-quasiparticle states probe the energies of the proton levels that govern the stability of superheavy nuclei, test 2-quasiparticle energies from theory, and thereby check their predictions of magic gaps
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