18,879 research outputs found
Modular Decomposition and the Reconstruction Conjecture
We prove that a large family of graphs which are decomposable with respect to
the modular decomposition can be reconstructed from their collection of
vertex-deleted subgraphs.Comment: 9 pages, 2 figure
Activity-dependent adenosine release may be linked to activation of Na+-K+ ATPase : an in vitro rat study
In the brain, extracellular adenosine increases as a result of neuronal activity. The mechanisms by which this occurs are only incompletely understood. Here we investigate the hypothesis that the Na+ influxes associated with neuronal signalling activate the Na+-K+ ATPase which, by consuming ATP, generates intracellular adenosine that is then released via transporters. By measuring adenosine release directly with microelectrode biosensors, we have demonstrated that AMPA-receptor evoked adenosine release in basal forebrain and cortex depends on extracellular Na+. We have simultaneously imaged intracellular Na+ and measured adenosine release. The accumulation of intracellular Na+ during AMPA receptor activation preceded adenosine release by some 90 s. By removing extracellular Ca2+, and thus preventing indiscriminate neuronal activation, we used ouabain to test the role of the Na+-K+ ATPase in the release of adenosine. Under conditions which caused a Na+ influx, brief applications of ouabain increased the accumulation of intracellular Na+ but conversely rapidly reduced extracellular adenosine levels. In addition, ouabain greatly reduced the amount of adenosine released during application of AMPA. Our data therefore suggest that activity of the Na+-K+ ATPase is directly linked to the efflux of adenosine and could provide a universal mechanism that couples adenosine release to neuronal activity. The Na+-K+ ATPase-dependent adenosine efflux is likely to provide adenosine-mediated activity-dependent negative feedback that will be important in many diverse functional contexts including the regulation of sleep
CO2-dependent opening of an inwardly rectifying K+ channel
CO2 chemosensing is a vital function for the
maintenance of life that helps to control acidβbase balance.
Most studies have reported that CO2 is measured via its
proxy, pH. Here we report an inwardly rectifying channel,
in outside-out excised patches from HeLa cells that was
sensitive to modest changes in PCO2 under conditions of
constant extracellular pH. As PCO2 increased, the open
probability of the channel increased. The single-channel
currents had a conductance of 6.7 pS and a reversal
potential of β70 mV, which lay between the K+ and Clβ
equilibrium potentials. This reversal potential was shifted
by +61 mV following a tenfold increase in extracellular
[K+] but was insensitive to variations of extracellular [Clβ].
The single-channel conductance increased with extracellular
[K+]. We propose that this channel is a member of the
Kir family. In addition to this K+ channel, we found that
many of the excised patches also contained a conductance
carried via a Clβ-selective channel. This CO2-sensitive Kir
channel may hyperpolarize excitable cells and provides a
potential mechanism for CO2-dependent inhibition during
hypercapnia
Strategies to Support Employer-Driven Initiatives to Recruit and Retain Employees with Disabilities
Across the United States, a growing number of employers have established initiatives to increase the participation of workers with disabilities within their companies. These employers typically establish partnerships with local workforce and disability service organizations to source for talent. Coordinated by a single agency (or small number of agencies), employers are provided assistance and support services for recruitment, training, and job retention for employees with disabilities. This research brief presents four profiles that highlight innovative practices among employers operating warehouse distribution centers in the U.S
Deliver Us From Evil: Why Bankruptcy Judges May Properly Rely on the Free Exercise Clause & RFRA To Protect Church Property From the Grasps of Tort-Creditors
Tidal Stresses and Energy Gaps in Microstate Geometries
We compute energy gaps and study infalling massive geodesic probes in the new
families of scaling, microstate geometries that have been constructed recently
and for which the holographic duals are known. We find that in the deepest
geometries, which have the lowest energy gaps, the geodesic deviation shows
that the stress reaches the Planck scale long before the probe reaches the cap
of the geometry. Such probes must therefore undergo a stringy transition as
they fall into microstate geometry. We discuss the scales associated with this
transition and comment on the implications for scrambling in microstate
geometries.Comment: 22 pages, 1 figur
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