1,539 research outputs found
The Massive Thermal Basketball Diagram
The "basketball diagram" is a three-loop vacuum diagram for a scalar field
theory that cannot be expressed in terms of one-loop diagrams. We calculate
this diagram for a massive scalar field at nonzero temperature, reducing it to
expressions involving three-dimensional integrals that can be easily evaluated
numerically. We use this result to calculate the free energy for a massive
scalar field with a phi^4 interaction to three-loop order.Comment: 19 pages, 3 figure
Evidence for nitrogen gas surface doping of the BiSe topological insulator
Using scanning tunneling spectroscopy we have studied the effects of nitrogen
gas exposure on the bismuth selenide density of states. We observe a shift in
the Dirac point which is qualitatively consistent with theoretical modeling of
nitrogen binding to selenium vacancies. In carefully controlled measurements,
BiSe crystals were initially cleaved in a helium gas environment and
then exposed to a 22 SCFH flow of ultra-high purity N gas. We observe a
resulting change in the spectral curves, with the exposure effect saturating
after approximately 50 minutes, ultimately bringing the Dirac point about 50
meV closer to the Fermi level. These results are compared to density functional
theoretical calculations, which support a picture of molecules
physisorbing near Se vacancies and dissociating into individual N atoms which
then bind strongly to Se vacancies. In this interpretation, the binding of the
N atom to a Se vacancy site removes the surface defect state created by the
vacancy and changes the position of the Fermi energy with respect to the Dirac
point.Comment: 9 pages, 3 figure
Persistent Pain Is Dependent on Spinal Mitochondrial Antioxidant Levels
Reactive oxygen species (ROS) scavengers have been shown to relieve persistent pain; however, the mechanism is not clearly understood.
Superoxide produced from mitochondrial oxidative phosphorylation is considered the major source of ROS in neurons during excitation
where mitochondrial superoxide levels are normally controlled by superoxide dismutase (SOD-2). The present study hypothesizes that
capsaicin-induced secondary hyperalgesia is a consequence of superoxide build-up in spinal dorsal horn neurons and SOD-2 is a major
determinant. To test this hypothesis, the spinal levels of SOD-2 activity, inactivated SOD-2 proteins, and mitochondrial superoxide were
measured and correlated to the levels of capsaicin-induced secondary hyperalgesia in mice with and without SOD-2 manipulations. The
data suggest that superoxide accumulation is a culprit in the abnormal sensory processing in the spinal cord in capsaicin-induced
secondary hyperalgesia. Our studies also support the notion that SOD-2 nitration is a critical mechanism that maintains elevated
superoxide levels in the spinal cord after capsaicin treatment. Finally, our findings suggest a therapeutic potential for the manipulation
of spinal SOD-2 activity in pain conditions.This work was supported by National Institutes of Health Grants R01 NS31680 and P01 NS11255
Linqits: Big data on little clients
ABSTRACT We present LINQits, a flexible hardware template that can be mapped onto programmable logic or ASICs in a heterogeneous system-on-chip for a mobile device or server. Unlike fixed-function accelerators, LINQits accelerates a domainspecific query language called LINQ. LINQits does not provide coverage for all possible applications-however, existing applications (re-)written with LINQ in mind benefit extensively from hardware acceleration. Furthermore, the LINQits framework offers a graceful and transparent migration path from software to hardware. LINQits is prototyped on a 2W heterogeneous SoC called the ZYNQ processor, which combines dual ARM A9 processors with an FPGA on a single die in 28nm silicon technology. Our physical measurements show that LINQits improves energy efficiency by 8.9 to 30.6 times and performance by 10.7 to 38.1 times compared to optimized, multithreaded C programs running on conventional ARM A9 processors
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