73 research outputs found
Anomalous relaxation and self-organization in non-equilibrium processes
We study thermal relaxation in ordered arrays of coupled nonlinear elements
with external driving. We find, that our model exhibits dynamic
self-organization manifested in a universal stretched-exponential form of
relaxation. We identify two types of self-organization, cooperative and
anti-cooperative, which lead to fast and slow relaxation, respectively. We give
a qualitative explanation for the behavior of the stretched exponent in
different parameter ranges. We emphasize that this is a system exhibiting
stretched-exponential relaxation without explicit disorder or frustration.Comment: submitted to PR
Potential and current distribution in strongly anisotropic Bi(2)Sr(2) CaCu(2)O(8) single crystals at current breakdown
Experiments on potential differences in the low-temperature vortex solid
phase of monocrystalline platelets of superconducting Bi(2)Sr(2)CaCu(2)O(8)
(BSCCO) subjected to currents driven either through an "ab" surface or from one
such surface to another show evidence of a resistive/nonresistive front moving
progressively out from the current contacts as the current increases. The depth
of the resistive region has been measured by a novel in-depth voltage probe
contact. The position of the front associated with an injection point appears
to depend only on the current magnitude and not on its withdrawal point. It is
argued that enhanced nonresistive superconducting anisotropy limits current
penetration to less than the London length and results in a flat rectangular
resistive region with simultaneous "ab" and "c" current breakdown which moves
progressively out from the injection point with increasing current.
Measurements in "ab" or "c" configurations are seen to give the same
information, involving both ab-plane and c-axis conduction properties.Comment: 9 pages, 13 figures, typo error corrected, last section was refine
Hall effect and conduction anisotropy in the organic conductor TMTSF2PF6
Long missing basic experiments in the normal phase of the anisotropic
electron system of TMTSF2PF6 were performed. Both the Hall effect and the
ab'-plane conduction anisotropy are directly addressing the unconventional
electrical properties of this Bechgaard salt. We found that the dramatic
reduction of the carrier density deduced from recent optical data is not
reflected in an enhanced Hall-resistance. The pressure- and temperature
dependence of the b'-direction resitivity reveal isotropic relaxation time and
do not require explanations beyond the Fermi liquid theory. Our results allow a
coherent-diffusive transition in the interchain carrier propagation, however
the possible crossover to Luttinger liquid behavior is placed to an energy
scale above room temperature.Comment: 5 pages, 5 figures, to be published in Phys. Rev. Let
Destruction of density-wave states by a pseudo-gap in high magnetic fields: application to (TMTSF)ClO
A model is presented for the destruction of density-wave states in
quasi-one-dimensional crystals by high magnetic fields. The model is consistent
with previously unexplained properties of the organic conductors
(TMTSF)ClO and (BEDT-TTF)MHg(SCN) (M=K,Rb,Tl). As the magnetic
field increases quasi-one-dimensional density-wave fluctuations increase,
producing a pseudo-gap in the electronic density of states near the transition
temperature. When the pseudo-gap becomes larger than the mean-field transition
temperature formation of a density-wave state is not possible.Comment: 4 pages, RevTeX, 2 figures in uuencoded compressed tar file. Small
changes to text and Figure 1. Final version to appear in Physical Review
Letter
Dental Health and Mortality in People With End-Stage Kidney Disease Treated With Hemodialysis: A Multinational Cohort Study
Background Dental disease is more extensive in adults with chronic kidney disease, but whether dental health and behaviors are associated with survival in the setting of hemodialysis is unknown. Study Design Prospective multinational cohort. Setting & Participants 4,205 adults treated with long-term hemodialysis, 2010 to 2012 (Oral Diseases in Hemodialysis [ORAL-D] Study). Predictors Dental health as assessed by a standardized dental examination using World Health Organization guidelines and personal oral care, including edentulousness; decayed, missing, and filled teeth index; teeth brushing and flossing; and dental health consultation. Outcomes All-cause and cardiovascular mortality at 12 months after dental assessment. Measurements Multivariable-adjusted Cox proportional hazards regression models fitted with shared frailty to account for clustering of mortality risk within countries. Results During a mean follow-up of 22.1 months, 942 deaths occurred, including 477 cardiovascular deaths. Edentulousness (adjusted HR, 1.29; 95% CI, 1.10-1.51) and decayed, missing, or filled teeth score ≥ 14 (adjusted HR, 1.70; 95% CI, 1.33-2.17) were associated with early all-cause mortality, while dental flossing, using mouthwash, brushing teeth daily, spending at least 2 minutes on oral hygiene daily, changing a toothbrush at least every 3 months, and visiting a dentist within the past 6 months (adjusted HRs of 0.52 [95% CI, 0.32-0.85], 0.79 [95% CI, 0.64-0.97], 0.76 [95% CI, 0.58-0.99], 0.84 [95% CI, 0.71-0.99], 0.79 [95% CI, 0.65-0.95], and 0.79 [95% CI, 0.65-0.96], respectively) were associated with better survival. Results for cardiovascular mortality were similar. Limitations Convenience sample of clinics. Conclusions In adults treated with hemodialysis, poorer dental health was associated with early death, whereas preventive dental health practices were associated with longer survival
Exploring the perspectives and preferences for HTA across German healthcare stakeholders using a multi-criteria assessment of a pulmonary heart sensor as a case study
Interaction of spin-density waves with defects and quasiparticles
The results of recent transport measurements in the spin-density wave (SDW) state of the Bechgaard salts (TMTSF)2X [X = PF6, AsF6, SbF6, or (AsF6)(1-x)(SbF6)x] are summarized. The weak nonmagnetic disorder introduced by the alloying of two kinds of anions increases the depinning threshold by up to 3 orders of magnitude. The damping of the low-frequency phase mode decreases exponentially with increasing temperature and saturates at a constant value determined by the disorder at high temperatures. The dc nonlinear conductivity disappears at low temperatures, and this behavior is not explained by the increasing damping. From Hall effect measurements we find a strong coupling between the SDW and normal electrons
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