1,947 research outputs found
Who Did It?: A Review on the Possible Causes of Multiple Sclerosis
Multiple Sclerosis (MS) is an incurable autoimmune disorder that attacks the myelin sheath surrounding nerve cells. Steady demyelination of these cells over time results in painful inflammation and reduced mobility. Genetic abnormalities could be responsible for the onset of this disease. Chromosomal mutations found in MS patients as well as environmental factors influencing the expression of certain genes will be analyzed in this review. Moreover, treatments regulating gene expression in MS patients will be discussed. Further genetic research would not only provide scientists and medical professionals with a deeper understanding of MS and other autoimmune disorders, but also lead to the development of more effective treatments. Recent findings have enabled scientists to identify genes in MS patients that are absent in healthy patients, but researchers struggle to find a common thread tying these genes together. This is just one of the many reasons why MS is still considered an idiopathic disease
Probing Non-Abelian Statistics in nu=12/5 Quantum Hall State
The tunneling current and shot noise of the current between two Fractional
Quantum Hall (FQH) edges in the FQH state in electronic
Mach-Zehnder interferometer are studied. It is shown that the tunneling current
and shot noise can be used to probe the existence of parafermion
statistics in the FQH state. More specifically, the dependence of
the current on the Aharonov-Bohm flux in the Read-Rezayi state is asymmetric
under the change of the sign of the applied voltage. This property is absent in
the Abelian Laughlin states. Moreover the Fano factor can exceed 12.7 electron
charges in the FQH state . This number well exceeds the maximum
possible Fano factor in all Laughlin states and the Moore-Read
state which was shown previously to be and respectively.Comment: 10 pages, 6 figure
An investigation of the competition between surface/internal latent-image formation in AgBr core-shell emulsions
The models for surface /internal latent-image formation by J.F. Hamilton and others were qualitatively investigated. Techniques were also developed to precipitate core-shell emulsions. Although the emulsion precipitation system employed was not highly stable, the major aspects of surface/ internal latent-image competition were successfully demonstrated. It was found that the level of surface /internal latent-image competition has a significant effect on the photographic response of core-shell emulsions
Global Perspectives on Large Dams: Evaluating the State of Large Dam Construction and Decommissioning Across the World
Report on a Conference held November 3-5, 2006 at the Yale School of Forestry & Environmental Studie
Current-dependent Block of Rabbit Sino-Atrial Node If Channels by Ivabradine
“Funny” (f-) channels have a key role in generation of spontaneous activity of pacemaker cells and mediate autonomic control of cardiac rate; f-channels and the related neuronal h-channels are composed of hyperpolarization-activated, cyclic nucleotide–gated (HCN) channel subunits. We have investigated the block of f-channels of rabbit cardiac sino-atrial node cells by ivabradine, a novel heart rate-reducing agent. Ivabradine is an open-channel blocker; however, block is exerted preferentially when channels deactivate on depolarization, and is relieved by long hyperpolarizing steps. These features give rise to use-dependent behavior. In this, the action of ivabradine on f-channels is similar to that reported of other rate-reducing agents such as UL-FS49 and ZD7288. However, other features of ivabradine-induced block are peculiar and do not comply with the hypothesis that the voltage-dependence of block is entirely attributable to either the sensitivity of ivabradine-charged molecules to the electrical field in the channel pore, or to differential affinity to different channel states, as has been proposed for UL-FS49 (DiFrancesco, D. 1994. Pflugers Arch. 427:64–70) and ZD7288 (Shin, S.K., B.S. Rotheberg, and G. Yellen. 2001. J. Gen. Physiol. 117:91–101), respectively. Experiments where current flows through channels is modified without changing membrane voltage reveal that the ivabradine block depends on the current driving force, rather than voltage alone, a feature typical of block induced in inwardly rectifying K+ channels by intracellular cations. Bound drug molecules do not detach from the binding site in the absence of inward current through channels, even if channels are open and the drug is therefore not “trapped” by closed gates. Our data suggest that permeation through f-channel pores occurs according to a multiion, single-file mechanism, and that block/unblock by ivabradine is coupled to ionic flow. The use-dependence resulting from specific features of If block by ivabradine amplifies its rate-reducing ability at high spontaneous rates and may be useful to clinical applications
Analytical approach to viscous fingering in a cylindrical Hele-Shaw cell
We report analytical results for the development of the viscous fingering
instability in a cylindrical Hele-Shaw cell of radius a and thickness b. We
derive a generalized version of Darcy's law in such cylindrical background, and
find it recovers the usual Darcy's law for flow in flat, rectangular cells,
with corrections of higher order in b/a. We focus our interest on the influence
of cell's radius of curvature on the instability characteristics. Linear and
slightly nonlinear flow regimes are studied through a mode-coupling analysis.
Our analytical results reveal that linear growth rates and finger competition
are inhibited for increasingly larger radius of curvature. The absence of
tip-splitting events in cylindrical cells is also discussed.Comment: 14 pages, 3 ps figures, Revte
Ward Identities of W_{\infty} Symmetry and Higher Genus Amplitudes in 2D String Theory
The Ward identities of the symmetry in two dimensional string
theory in the tachyon background are studied in the continuum approach. We
consider amplitudes different from 2D string ones by the external leg factor
and derive the recursion relations among them. The recursion relations have
non-linear terms which give relations among the amplitudes defined on different
genus. The solutions agree with the matrix model results even in higher genus.
We also discuss differences of roles of the external leg factor between the
model and the model.Comment: 21 pages, Latex, 5 figures. Revised version published in Nucl. Phys.
B. Errors of coefficients in some formula and the potential term are
corrected. Some sentences are rewritte
Macroscopoic Three-Loop Amplitudes and the Fusion Rules from the Two-Matrix Model
From the computation of three-point singlet correlators in the two-matrix
model, we obtain an explicit expression for the macroscopic three-loop
amplitudes having boundary lengths in the case of
the unitary series coupled to two-dimensional gravity. The sum
appearing in this expression is found to conform to the structure of the CFT
fusion rules while the summand factorizes through a product of three modified
Bessel functions. We briefly discuss a possible generalization of these
features to macroscopic -loop amplitudes.Comment: 9 pages, no figure, late
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