350 research outputs found
Morocco and the Netherlands
This book on aspects of society, economy and culture in Morocco and the Netherlands contains contributions of 28 Moroccan and Dutch authors on religion, family and marriage law, local government and PJD, Abdelkrim, Morocco and the EU, drug trafficking, migration, youth, Dutch-Moroccan writers, and architecture, and focuses on the tension between tradition and modernity
Fast Algorithms For Josephson Junction Arrays : Bus--bars and Defects
We critically review the fast algorithms for the numerical study of
two--dimensional Josephson junction arrays and develop the analogy of such
systems with electrostatics. We extend these procedures to arrays with
bus--bars and defects in the form of missing bonds. The role of boundaries and
of the guage choice in determing the Green's function of the system is
clarified. The extension of the Green's function approach to other situations
is also discussed.Comment: Uuencoded 1 Revtex file (11 Pages), 3 Figures : Postscript Uuencode
Political Regimes and Sovereign Credit Risk in Europe, 1750-1913
This article uses a new panel data set to perform a statistical analysis of political regimes and sovereign credit risk in Europe from 1750 to 1913. Old Regime polities typically suffered from fiscal fragmentation and absolutist rule. By the start of World War I, however, many such countries had centralized institutions and limited government. Panel regressions indicate that centralized and?or limited regimes were associated with significant improvements in credit risk relative to fragmented and absolutist ones. Structural break tests also reveal close relationships between major turning points in yield series and political transformations
Critical properties of two-dimensional Josephson junction arrays with zero-point quantum fluctuations
We present results from an extensive analytic and numerical study of a
two-dimensional model of a square array of ultrasmall Josephson junctions. We
include the ultrasmall self and mutual capacitances of the junctions, for the
same parameter ranges as those produced in the experiments. The model
Hamiltonian studied includes the Josephson, , as well as the charging,
, energies between superconducting islands. The corresponding quantum
partition function is expressed in different calculationally convenient ways
within its path-integral representation. The phase diagram is analytically
studied using a WKB renormalization group (WKB-RG) plus a self-consistent
harmonic approximation (SCHA) analysis, together with non-perturbative quantum
Monte Carlo simulations. Most of the results presented here pertain to the
superconductor to normal (S-N) region, although some results for the insulating
to normal (I-N) region are also included. We find very good agreement between
the WKB-RG and QMC results when compared to the experimental data. To fit the
data, we only used the experimentally determined capacitances as fitting
parameters. The WKB-RG analysis in the S-N region predicts a low temperature
instability i.e. a Quantum Induced Transition (QUIT). We carefully simulations
and carry out a finite size analysis of as a function of the
magnitude of imaginary time axis . We find that for some relatively
large values of (, the
limit does appear to give a {\it non-zero} , while
for , . We use the SCHA to analytically understand
the dependence of the QMC results with good agreement between them.
Finally, we also carried out a WKB-RG analysis in the I-N region and found no
evidence of a low temperature QUIT, up to lowest order in Comment: 39 pages, 18 postscript figures, to appear in Phys. Rev.
Randomized clinical trial of endovenous laser ablation versus direct and indirect radiofrequency ablation for the treatment of great saphenous varicose veins
Background: The current treatment strategy for many patients with varicose veins is endovenous thermal
ablation. The most common forms of this are endovenous laser ablation (EVLA) and radiofrequency
ablation (RFA). However, at present there is no clear consensus on which of these treatments is
superior. The objective of this study was to compare EVLA with two forms of RFA: direct RFA (dRFA;
radiofrequency-induced thermotherapy) and indirect RFA (iRFA; VNUS ClosureFast™).
Methods: Patients with symptomatic great saphenous vein (GSV) incompetence were randomized
to receive EVLA, dRFA or iRFA. Patients were followed up at 2 weeks, 6 and 12 months. The primary
outcome was GSV occlusion rate. Secondary outcomes included Venous Clinical Severity Score (VCSS),
Aberdeen Varicose Vein Questionnaire (AVVQ) score and adverse events.
Results: Some 450 patients received the allocated treatment (EVLA, 148; dRFA, 152; iRFA, 150). The
intention-to-treat analysis showed occlusion rates of 75⋅0 (95 per cent c.i. 68⋅0 to 82⋅0), 59⋅9 (52⋅1 to 67⋅7)
and 81⋅3 (75⋅1 to 87⋅6) per cent respectively after 1 year (P = 0⋅007 for EVLA versus dRFA, P < 0⋅001 for
dRFA versus iRFA, P = 0⋅208 for EVLA versus iRFA). VCSS improved significantly for all treatments with
no significant differences between them. AVVQ scores also improved significantly for all treatments, but
iRFA had significantly better scores than dRFA at 12 months. Significantly more adverse events were
reported after treatment with EVLA (103) than after dRFA (61) and iRFA (65), especially more pain.
Conclusion: Primary GSV occlusion rates were better after iRFA and EVLA than dRFA. All three
interventions were effective in improving the clinical severity of varicose veins at 1 year
Quantum-Phase Transitions of Interacting Bosons and the Supersolid Phase
We investigate the properties of strongly interacting bosons in two
dimensions at zero temperature using mean-field theory, a variational Ansatz
for the ground state wave function, and Monte Carlo methods. With on-site and
short-range interactions a rich phase diagram is obtained. Apart from the
homogeneous superfluid and Mott-insulating phases, inhomogeneous charge-density
wave phases appear, that are stabilized by the finite-range interaction.
Furthermore, our analysis demonstrates the existence of a supersolid phase, in
which both long-range order (related to the charge-density wave) and
off-diagonal long-range order coexist. We also obtain the critical exponents
for the various phase transitions.Comment: RevTex, 20 pages, 10 PostScript figures include
Analysis of hyperekplexia mutations identifies transmembrane domain rearrangements that mediate glycine receptor activation
Pentameric ligand-gated ion channels (pLGICs) mediate numerous physiological processes and are therapeutic targets for a wide range of clinical indications. Elucidating the structural differences between their closed and open states may help in designing improved drugs that bias receptors toward the desired conformational state. We recently showed that two new hyperekplexia mutations, Q226E and V280M, induced spontaneous activity in α1 glycine receptors. Gln-226, located near the top of transmembrane (TM) 1, is closely apposed to Arg-271 at the top of TM2 in the neighboring subunit. Using mutant cycle analysis, we inferred that Q226E induces activation via an enhanced electrostatic attraction to Arg-271. This would tilt the top of TM2 toward TM1 and hence away from the pore axis to open the channel. We also concluded that the increased side chain volume of V280M, in the TM2-TM3 loop, exerts a steric repulsion against Ile-225 at the top of TM1 in the neighboring subunit. We infer that this steric repulsion would tilt the top of TM3 radially outwards against the stationary TM1 and thus provide space for TM2 to relax away from the pore axis to create an open channel. Because the transmembrane domain movements inferred from this functional analysis are consistent with the structural differences evident in the x-ray atomic structures of closed and open state bacterial pLGICs, we propyose that the model of pLGIC activation as outlined here may be broadly applicable across the eukaryotic pLGIC receptor family
The superconductor-insulator transition in 2D dirty boson systems
Universal properties of the zero temperature superconductor-insulator
transition in two-dimensional amorphous films are studied by extensive Monte
Carlo simulations of bosons in a disordered medium. We report results for both
short-range and long-range Coulomb interactions for several different points in
parameter space. In all cases we observe a transition from a superconducting
phase to an insulating Bose glass phase. {}From finite-size scaling of our
Monte Carlo data we determine the universal conductivity and the
critical exponents at the transition. The result for bosons with long-range Coulomb interaction is roughly consistent
with experiments reported so far. We also find for bosons with short-range interactions.Comment: Revtex 3.0, 54 pages, 17 figures included, UBCTP-93-01
Projections from the paralemniscal nucleus to the spinal cord in the mouse
The present study investigated the projection from the paralemniscal nucleus (PL) to the spinal cord in the mouse by injecting the retrograde tracer fluoro-gold to different levels of the spinal cord and injecting the anterograde tracer biotinylated dextran amine into PL. We found that PL projects to the entire spinal cord with obvious contralateral predominance—420 neurons projected to the contralateral cervical cord and 270 to the contralateral lumbar cord. Fibers from PL descended in the dorsolateral funiculus on the contralateral side and terminated in laminae 5, 6, 7, and to a lesser extent in the dorsal and ventral horns. A smaller number of fibers also descended in the ventral funiculus on the ipsilateral side and terminated in laminae 7, 8 and, to a lesser extent in lamina 9. The present study is the first demonstration of the PL fiber termination in the spinal cord in mammals. The PL projection to the spinal cord may be involved in vocalization and locomotion
Antihyperalgesia by α2-GABAA Receptors Occurs Via a Genuine Spinal Action and Does Not Involve Supraspinal Sites
Drugs that enhance GABAergic inhibition alleviate inflammatory and neuropathic pain after spinal application. This antihyperalgesia occurs mainly through GABAA receptors (GABAARs) containing α2 subunits (α2-GABAARs). Previous work indicates that potentiation of these receptors in the spinal cord evokes profound antihyperalgesia also after systemic administration, but possible synergistic or antagonistic actions of supraspinal α2-GABAARs on spinal antihyperalgesia have not yet been addressed. Here we generated two lines of GABAAR-mutated mice, which either lack α2-GABAARs specifically from the spinal cord, or, which express only benzodiazepine-insensitive α2-GABAARs at this site. We analyzed the consequences of these mutations for antihyperalgesia evoked by systemic treatment with the novel non-sedative benzodiazepine site agonist HZ166 in neuropathic and inflammatory pain. Wild-type mice and both types of mutated mice had similar baseline nociceptive sensitivities and developed similar hyperalgesia. However, antihyperalgesia by systemic HZ166 was reduced in both mutated mouse lines by about 60% and was virtually indistinguishable from that of global point-mutated mice, in which all α2-GABAARs were benzodiazepine insensitive. The major (α2-dependent) component of GABAAR-mediated antihyperalgesia was therefore exclusively of spinal origin, whereas supraspinal α2-GABAARs had neither synergistic nor antagonistic effects on antihyperalgesia. Our results thus indicate that drugs that specifically target α2-GABAARs exert their antihyperalgesic effect through enhanced spinal nociceptive control. Such drugs may therefore be well-suited for the systemic treatment of different chronic pain conditions
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