3,592 research outputs found
Small molecule studies: the fourth wave of muscle research
The study of muscle and contractility is an unusual scientific endeavour since it has from the start been focussed on one problem-What makes muscle work?-and yet has needed a vast range of different approaches and techniques to study it. Its uniqueness lies in the fundamental fascination of a large scale molecular machine that converts chemical energy into mechanical energy at ambient temperature and with high efficiency that is also controlled by an exquisitely intricate yet utterly reliable regulatory system and is an essential component of animal life. The investigation of muscle is as innovative as any other field of research. As soon as one approach appears to be played out another comes along. It is instructive to consider this as a series of waves of novel and heightened activity starting in the 1950s. The thesis of this article is that we are approaching the fourth wave with the recent rise of interest in small molecules as research tools and possible therapies for muscle diseases
Resonances, radiation pressure and optical scattering phenomena of drops and bubbles
Acoustic levitation and the response of fluid spheres to spherical harmonic projections of the radiation pressure are described. Simplified discussions of the projections are given. A relationship between the tangential radiation stress and the Konstantinov effect is introduced and fundamental streaming patterns for drops are predicted. Experiments on the forced shape oscillation of drops are described and photographs of drop fission are displayed. Photographs of critical angle and glory scattering by bubbles and rainbow scattering by drops are displayed
Short-coherence length superconductivity in the Attractive Hubbard Model in three dimensions
We study the normal state and the superconducting transition in the
Attractive Hubbard Model in three dimensions, using self-consistent
diagrammatics. Our results for the self-consistent -matrix approximation are
consistent with 3D-XY power-law critical scaling and finite-size scaling. This
is in contrast to the exponential 2D-XY scaling the method was able to capture
in our previous 2D calculation. We find the 3D transition temperature at
quarter-filling and to be . The 3D critical regime is much
narrower than in 2D and the ratio of the mean-field transition to is
about 5 times smaller than in 2D. We also find that, for the parameters we
consider, the pseudogap regime in 3D (as in 2D) coincides with the critical
scaling regime.Comment: 4 pages, 5 figure
Alien Registration- Marston, Guy S. (Presque Isle, Aroostook County)
https://digitalmaine.com/alien_docs/33739/thumbnail.jp
Non-invasive brain stimulation techniques for chronic pain
Copyright © 2014 The Cochrane Collaboration.Various devices are available that can electrically stimulate the brain without the need for surgery or any invasive treatment in order to manage chronic pain. There are four main treatment types: repetitive transcranial magnetic stimulation (rTMS) in which the brain is stimulated by a coil applied to the scalp, cranial electrotherapy stimulation (CES) in which electrodes are clipped to the ears or applied to the scalp, transcranial direct current stimulation (tDCS) and reduced impedance non-invasive cortical electrostimulation (RINCE) in which electrodes are applied to the scalp. These have been used to try to reduce pain by aiming to alter the activity of the brain, but the efficacy of these treatments is uncertain.
This review update included 56 studies: 30 of rTMS, 11 of CES, 14 of tDCS and one of RINCE. We judged only three studies as having a low risk of bias. Low or very low-quality evidence suggests that low-frequency rTMS and rTMS applied to pre-frontal areas of the brain are not effective but that a single dose of high-frequency stimulation of the motor cortex area of the brain provides short-term pain relief. This effect appears to be small and may be exaggerated by a number of sources of bias. Studies that gave a course of multiple treatments of rTMS produced conflicting results with no overall effect seen when we pooled the results of these studies. Most studies of rTMS are small and there is substantial variation between studies in terms of the treatment methods used. Low-quality evidence does not suggest that CES or tDCS are effective treatments for chronic pain. A single small study of RINCE provided very low-quality evidence of a short-term effect on pain. For all forms of stimulation the evidence is not conclusive and uncertainty remains.
The reporting of side effects varied across the studies. Of the studies that clearly reported side effects, short-lived and minor side effects such as headache, nausea and skin irritation were usually reported both after real and sham stimulation. There were two reports of seizure following real rTMS.
While the broad conclusions for rTMS and CES have not changed substantially, the addition of this new evidence and the application of the GRADE system has modified some of our interpretation. Previous readers should re-read this update.
More studies of rigorous design and adequate size are required to evaluate accurately all forms of non-invasive brain stimulation for the treatment of chronic pain
Transport anomalies in a simplified model for a heavy electron quantum critical point
We discuss the transport anomalies associated with the development of heavy
electrons out of a neutral spin fluid using the large-N treatment of the
Kondo-Heisenberg lattice model. At the phase transition in this model the spin
excitations suddenly acquire charge. The Higgs process by which this takes
place causes the constraint gauge field to loosely ``lock'' together with the
external, electromagnetic gauge field. From this perspective, the heavy fermion
phase is a Meissner phase in which the field representing the difference
between the electromagnetic and constraint gauge field, is excluded from the
material. We show that at the transition into the heavy fermion phase, both the
linear and the Hall conductivity jump together. However, the Drude weight of
the heavy electron fluid does not jump at the quantum critical point, but
instead grows linearly with the distance from the quantum critical point,
forming a kind of ``gossamer'' Fermi-liquid.Comment: 15 pages, 3 figures. Small change in references in v
Strong Correlations in Actinide Redox Reactions
Reduction-oxidation (redox) reactions of the redox couples An(VI)/An(V),
An(V)/An(IV), and An(IV)/An(III), where An is an element in the family of early
actinides (U, Np, and Pu), as well as Am(VI)/Am(V) and Am(V)/Am(III), are
modeled by combining density functional theory with a generalized Anderson
impurity model that accounts for the strong correlations between the 5f
electrons. Diagonalization of the Anderson impurity model yields improved
estimates for the redox potentials and the propensity of the actinide complexes
to disproportionate.Comment: 17 pages, 10 figure, 3 tables. Corrections and clarifications; this
version has been accepted for publication in The Journal of Chemical Physic
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