2,454 research outputs found
Stripes, Non-Fermi-Liquid Behavior, and High-Tc Superconductivity
The electronic structure of the high-Tc cuprates is studied in terms of
"large-U" and "small-U" orbitals. A striped structure and three types of
quasiparticles are obtained, polaron-like "stripons" carrying charge, "svivons"
carrying spin, and "quasielectrons" carrying both. The anomalous properties are
explained, and specifically the behavior of the resistivity, Hall constant, and
thermoelectric power. High-temperature superconductivity results from
transitions between pair states of quasielectrons and stripons.Comment: 4 page
Zonisamide for migraine prophylaxis in refractory patients
Zonisamide, a new antiepileptic drug, has been approved in the US as adjunctive therapy for the treatment of partial seizures in adults.1,2 Chemically a sulfonamide analogue, zonisamide is thought to have several mechanisms of action, including a rate-dependent blockade of voltage-gated sodium channels and reduction of ion flow through T-type calcium channels.3-5 It is also a weak carbonic anhydrase inhibitor. Zonisamide has a favorable pharmacokinetic profile that includes high oral bioavailability and a long half life (63 hours), permitting a once- or twice-daily dosing regimen.6
There are only a limited number of current migraine preventive medications that have proven efficacy. Their use is often limited because of adverse events (AEs) in a significant number of patients.7 Because of its pharmacologic properties, zonisamide is potentially an effective drug for migraine prevention, and preliminary data suggest that it may be effective for this indication.8-10 The long half life of the drug makes it a good candidate for migraine patients who have poor compliance to preventive therapy that involves multiple daily dosing.
The aim of this study was to evaluate the efficacy and tolerability of zonisamide for migraine prophylaxis in refractory patients attending a tertiary headache center
On the evolution of decoys in plant immune systems
The Guard-Guardee model for plant immunity describes how resistance proteins
(guards) in host cells monitor host target proteins (guardees) that are
manipulated by pathogen effector proteins. A recently suggested extension of
this model includes decoys, which are duplicated copies of guardee proteins,
and which have the sole function to attract the effector and, when modified by
the effector, trigger the plant immune response. Here we present a
proof-of-principle model for the functioning of decoys in plant immunity,
quantitatively developing this experimentally-derived concept. Our model links
the basic cellular chemistry to the outcomes of pathogen infection and
resulting fitness costs for the host. In particular, the model allows
identification of conditions under which it is optimal for decoys to act as
triggers for the plant immune response, and of conditions under which it is
optimal for decoys to act as sinks that bind the pathogen effectors but do not
trigger an immune response.Comment: 15 pages, 6 figure
Hemicrania continua-like headache associated with carotid dissection may respond to indomethacin
Hemicrania continua (HC) is an idiopathic, chronic disorder characterized by a continuous, strictly unilateral headache associated with ipsilateral cranial autonomic symptoms. The symptoms of HC typically respond dramatically to indomethacin therapy. We describe a patient with traumatic internal carotid artery (ICA) dissection, who presented with a clinical picture mimicking HC that initially responded to indomethacin. Patients with a clinical picture similar to HC should be managed with a high index of suspicion for a possible cervical arterial dissection
The energy budget in Rayleigh-Benard convection
It is shown using three series of Rayleigh number simulations of varying
aspect ratio AR and Prandtl number Pr that the normalized dissipation at the
wall, while significantly greater than 1, approaches a constant dependent upon
AR and Pr. It is also found that the peak velocity, not the mean square
velocity, obeys the experimental scaling of Ra^{0.5}. The scaling of the mean
square velocity is closer to Ra^{0.46}, which is shown to be consistent with
experimental measurements and the numerical results for the scaling of Nu and
the temperature if there are strong correlations between the velocity and
temperature.Comment: 5 pages, 3 figures, new version 13 Mar, 200
Ordered and periodic chaos of the bounded one dimensinal multibarrier potential
Numerical analysis indicates that there exists an unexpected new ordered
chaos for the bounded one-dimensional multibarrier potential. For certain
values of the number of barriers, repeated identical forms (periods) of the
wavepackets result upon passing through the multibarrier potential.Comment: 16 pages, 9 figures, 1 Table. Some former text removed and other
introduce
Structure and Fracture Visualization of Tilted ABS Specimens Processed via Fused Filament Fabrication Additive Manufacturing
Fused filament fabrication (FFF) technique is one of the most frequently used additive manufacturing (AM) technologies for printing ABS and many other thermoplastic materials. The anisotropy of the mechanical properties of 3D-printed parts manufactured by FFF technology is still of major concern when using this technique. Thus, the component’s orientation, build strategy and printing parameters affect the mechanical properties, and failure mechanisms are of crucial importance. This research aims to partly fill this gap by studying the structure and mechanical behavior of FFF-ABS specimens, and by performing fracture surface analysis by the three-point bend flexural test. A series of tests were conducted to determine the flexural properties of tilted specimens at 0°, 15°, 30°, 45°, 60° and 75° inclination angles relative to the machine platform. The work describes manufacture method of the specimens, experimental procedures, and outcomes from the mechanical and structural characterizations of the FFF-ABS specimens. Overall, two main failure modes were observed for the tested specimens: (1) inter-layer/ inter-raster bond failure (typical for upright specimens) and (2) intra-layer/trans-raster failure (typical for on-edge specimens). A mixed inter-layer/ intra-layer mode was found for the specimens tilted in-between the 15o and 60o range
Cytoscape ESP: simple search of complex biological networks
Summary: Cytoscape enhanced search plugin (ESP) enables searching complex biological networks on multiple attribute fields using logical operators and wildcards. Queries use an intuitive syntax and simple search line interface. ESP is implemented as a Cytoscape plugin and complements existing search functions in the Cytoscape network visualization and analysis software, allowing users to easily identify nodes, edges and subgraphs of interest, even for very large networks
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The stress-sensing domain of activated IRE1α forms helical filaments in narrow ER membrane tubes
The signaling network of the unfolded protein response (UPR) adjusts the protein folding capacity of the endoplasmic reticulum (ER) according to need. The most conserved UPR sensor, IRE1α, spans the ER membrane and activates through oligomerization. IRE1α oligomers accumulate in dynamic foci. We determined the in-situ structure of IRE1α foci by cryogenic correlated light and electron microscopy (cryo-CLEM), combined with electron cryo-tomography (cryo-ET) and complementary immuno-electron microscopy. IRE1α oligomers localize to a network of narrow anastomosing ER tubes (diameter ~28 nm) with complex branching. The lumen of the tubes contains protein filaments, likely composed of linear arrays of IRE1α lumenal domain dimers, arranged in two intertwined, left-handed helices. Our findings define a previously unrecognized ER subdomain and suggest positive feedback in IRE1 signaling
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