4,558 research outputs found
Party Competition in Illinois: Republican Prospects in a Blue State
Campaigns and elections in Illinois are always interesting and exciting spectacles. They are full of colorful characters, great plots, and unexpected twists to the story line. Each election brings new characters and different stories, but each builds on the rich tradition and culture of a big and diverse state which takes its politics and politicians quite seriously. A state which over the last half century has produced such notables as Everett Dirksen, Paul Douglas, Adlai Stevenson, Jr., Charles Percy, Paul Simon, Alan Dixon, Richard Ogilvie, Dan Walker, Dan Rostenkowski, Richard J. Daley, Harold Washington, Richard M. Daley, Russell Arrington, Phil Rock, Michael Madigan, Pate Phillip, Roland Burris, George Ryan, Jim Edgar, Jim Thompson, Richard Durbin, Barack Obama, Emil Jones, Judy Barr Topinka, and Rod Blagojevich clearly has a great political culture and a compelling political history. We have had our scoundrels and some have ended up in federal prison. We have had our statesmen of the past and some of our present leaders hold national office with great prominence and prospects for national leadership
Single channel properties of a volume sensitive anion channel: Lessons from noise analysis
Single channel properties of a volume sensitive anion channel: Lessons from noise analysis. Swelling activated anion channels have recently been recognized to play an important role in not only volume regulatory electrolyte movement, but also in organic osmolyte transport. A swelling-activated, outwardly rectifying anion channel termed VSOAC (volume-sensitive organic osmolyte/anion channel) is a major pathway for swelling-induced loss of organic osmolytes and organic anions from mammalian cells. VSOAC has been described in numerous cell types. Until recently, however, the unitary conductance and gating kinetics of VSOAC were uncertain. Stationary noise analysis and single channel measurements have produced estimates for the unitary conductance of swelling-activated, outwardly rectifying anion channels that vary by > 15-fold. This review describes our current understanding of the single channel properties of VSOAC
Validity of effective material parameters for optical fishnet metamaterials
Although optical metamaterials that show artificial magnetism are mesoscopic
systems, they are frequently described in terms of effective material
parameters. But due to intrinsic nonlocal (or spatially dispersive) effects it
may be anticipated that this approach is usually only a crude approximation and
is physically meaningless. In order to study the limitations regarding the
assignment of effective material parameters, we present a technique to retrieve
the frequency-dependent elements of the effective permittivity and permeability
tensors for arbitrary angles of incidence and apply the method exemplarily to
the fishnet metamaterial. It turns out that for the fishnet metamaterial,
genuine effective material parameters can only be introduced if quite stringent
constraints are imposed on the wavelength/unit cell size ratio. Unfortunately
they are only met far away from the resonances that induce a magnetic response
required for many envisioned applications of such a fishnet metamaterial. Our
work clearly indicates that the mesoscopic nature and the related spatial
dispersion of contemporary optical metamaterials that show artificial magnetism
prohibits the meaningful introduction of conventional effective material
parameters
Increased GABA Contributes to Enhanced Control over Motor Excitability in Tourette Syndrome
Tourette syndrome (TS) is a developmental neurological disorder characterized by vocal and motor tics [1] and associated with cortical-striatal-thalamic-cortical circuit dysfunction [2, 3], hyperexcitability within cortical motor areas [4], and altered intracortical inhibition [4, 5, 6, 7]. TS often follows a developmental time course in which tics become increasingly more controlled during adolescence in many individuals [1], who exhibit enhanced control over their volitional movements [8, 9, 10, 11]. Importantly, control over motor outputs appears to be brought about by a reduction in the gain of motor excitability [6, 7, 12, 13]. Here we present a neurochemical basis for a localized gain control mechanism. We used ultra-high-field (7 T) magnetic resonance spectroscopy to investigate in vivo concentrations of γ-aminobutyric acid (GABA) within primary and secondary motor areas of individuals with TS. We demonstrate that GABA concentrations within the supplementary motor area (SMA)—a region strongly associated with the genesis of motor tics in TS [14]—are paradoxically elevated in individuals with TS and inversely related to fMRI blood oxygen level-dependent activation. By contrast, GABA concentrations in control sites do not differ from those of a matched control group. Importantly, we also show that GABA concentrations within the SMA are inversely correlated with cortical excitability in primary motor cortex and are predicted by motor tic severity and white-matter microstructure (FA) within a region of the corpus callosum that projects to the SMA within each hemisphere. Based upon these findings, we propose that extrasynaptic GABA contributes to a form of control, based upon localized tonic inhibition within the SMA, that may lead to the suppression of tics
Gibbs Sampling with Low-Power Spiking Digital Neurons
Restricted Boltzmann Machines and Deep Belief Networks have been successfully
used in a wide variety of applications including image classification and
speech recognition. Inference and learning in these algorithms uses a Markov
Chain Monte Carlo procedure called Gibbs sampling. A sigmoidal function forms
the kernel of this sampler which can be realized from the firing statistics of
noisy integrate-and-fire neurons on a neuromorphic VLSI substrate. This paper
demonstrates such an implementation on an array of digital spiking neurons with
stochastic leak and threshold properties for inference tasks and presents some
key performance metrics for such a hardware-based sampler in both the
generative and discriminative contexts.Comment: Accepted at ISCAS 201
First-principles calculations of magnetization relaxation in pure Fe, Co, and Ni with frozen thermal lattice disorder
The effect of the electron-phonon interaction on magnetization relaxation is
studied within the framework of first-principles scattering theory for Fe, Co,
and Ni by displacing atoms in the scattering region randomly with a thermal
distribution. This "frozen thermal lattice disorder" approach reproduces the
non-monotonic damping behaviour observed in ferromagnetic resonance
measurements and yields reasonable quantitative agreement between calculated
and experimental values. It can be readily applied to alloys and easily
extended by determining the atomic displacements from ab initio phonon spectra
Determination of energy transfer parameters in Er<sup>3+</sup>-doped and Er<sup>3+</sup>, Pr<sup>3+</sup>-codoped ZBLAN glasses
Mass and dust in the disk of a spiral lens galaxy
Gravitational lensing is a potentially important probe of spiral galaxy
structure, but only a few cases of lensing by spiral galaxies are known. We
present Hubble Space Telescope and Magellan observations of the two-image
quasar PMN J2004-1349, revealing that the lens galaxy is a spiral galaxy. One
of the quasar images passes through a spiral arm of the galaxy and suffers 3
magnitudes of V-band extinction. Using simple lens models, we show that the
mass quadrupole is well-aligned with the observed galaxy disk. A more detailed
model with components representing the bulge and disk gives a bulge-to-disk
mass ratio of 0.16 +/- 0.05. The addition of a spherical dark halo, tailored to
produce an overall flat rotation curve, does not change this conclusion.Comment: ApJ, in press [9pp, 7 figs
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