445 research outputs found
New β Cep pulsators discovered with K2 space photometry
Contains fulltext :
207549.pdf (publisher's version ) (Open Access
The Non-Trivial Effective Potential of the `Trivial' lambda Phi^4 Theory: A Lattice Test
The strong evidence for the `triviality' of (lambda Phi^4)_4 theory is not
incompatible with spontaneous symmetry breaking. Indeed, for a `trivial' theory
the effective potential should be given exactly by the classical potential plus
the free-field zero-point energy of the shifted field; i.e., by the one-loop
effective potential. When this is renormalized in a simple, but nonperturbative
way, one finds, self-consistently, that the shifted field does become
non-interacting in the continuum limit. For a classically scale-invariant (CSI)
lambda Phi^4 theory one finds m_h^2 = 8 pi^2 v^2, predicting a 2.2 TeV Higgs
boson. Here we extend our earlier work in three ways: (i) we discuss the
analogy with the hard-sphere Bose gas; (ii) we extend the analysis from the CSI
case to the general case; and (iii) we propose a test of the predicted shape of
the effective potential that could be tested in a lattice simulation.Comment: 22 pages, LaTeX, DE-FG05-92ER40717-
Adiabatic quantum pump in the presence of external ac voltages
We investigate a quantum pump which in addition to its dynamic pump
parameters is subject to oscillating external potentials applied to the
contacts of the sample. Of interest is the rectification of the ac currents
flowing through the mesoscopic scatterer and their interplay with the quantum
pump effect. We calculate the adiabatic dc current arising under the
simultaneous action of both the quantum pump effect and classical
rectification. In addition to two known terms we find a third novel
contribution which arises from the interference of the ac currents generated by
the external potentials and the ac currents generated by the pump. The
interference contribution renormalizes both the quantum pump effect and the ac
rectification effect. Analysis of this interference effect requires a
calculation of the Floquet scattering matrix beyond the adiabatic approximation
based on the frozen scattering matrix alone. The results permit us to find the
instantaneous current. In addition to the current generated by the oscillating
potentials, and the ac current due to the variation of the charge of the frozen
scatterer, there is a third contribution which represents the ac currents
generated by an oscillating scatterer. We argue that the resulting pump effect
can be viewed as a quantum rectification of the instantaneous ac currents
generated by the oscillating scatterer. These instantaneous currents are an
intrinsic property of a nonstationary scattering process.Comment: 11 pages, 1 figur
Dissipation and noise in adiabatic quantum pumps
We investigate the distribution function, the heat flow and the noise
properties of an adiabatic quantum pump for an arbitrary relation of pump
frequency and temperature. To achieve this we start with the
scattering matrix approach for ac-transport. This approach leads to expressions
for the quantities of interest in terms of the side bands of particles exiting
the pump. The side bands correspond to particles which have gained or lost a
modulation quantum . We find that our results for the pump
current, the heat flow and the noise can all be expressed in terms of a
parametric emissivity matrix. In particular we find that the current
cross-correlations of a multiterminal pump are directly related a to a
non-diagonal element of the parametric emissivity matrix. The approach allows a
description of the quantum statistical correlation properties (noise) of an
adiabatic quantum pump
Benchmarking the HLA typing performance of Polysolver and Optitype in 50 Danish parental trios
A Conformally Invariant Holographic Two-Point Function on the Berger Sphere
We apply our previous work on Green's functions for the four-dimensional
quaternionic Taub-NUT manifold to obtain a scalar two-point function on the
homogeneously squashed three-sphere (otherwise known as the Berger sphere),
which lies at its conformal infinity. Using basic notions from conformal
geometry and the theory of boundary value problems, in particular the
Dirichlet-to-Robin operator, we establish that our two-point correlation
function is conformally invariant and corresponds to a boundary operator of
conformal dimension one. It is plausible that the methods we use could have
more general applications in an AdS/CFT context.Comment: 1+49 pages, no figures. v2: Several typos correcte
Mitochondrial Release of Caspase-2 and -9 during the Apoptotic Process
The barrier function of mitochondrial membranes is perturbed early during the apoptotic process. Here we show that the mitochondria contain a caspase-like enzymatic activity cleaving the caspase substrate Z-VAD.afc, in addition to three biological activities previously suggested to participate in the apoptotic process: (a) cytochrome c; (b) an apoptosis-inducing factor (AIF) which causes isolated nuclei to undergo apoptosis in vitro; and (c) a DNAse activity. All of these factors, which are biochemically distinct, are released upon opening of the permeability transition (PT) pore in a coordinate, Bcl-2–inhibitable fashion. Caspase inhibitors fully neutralize the Z-VAD.afc–cleaving activity, have a limited effect on the AIF activity, and have no effect at all on the DNase activities. Purification of proteins reacting with the biotinylated caspase substrate Z-VAD, immunodetection, and immunodepletion experiments reveal the presence of procaspase-2 and -9 in mitochondria. Upon induction of PT pore opening, these procaspases are released from purified mitochondria and become activated. Similarly, upon induction of apoptosis, both procaspases redistribute from the mitochondrion to the cytosol and are processed to generate enzymatically active caspases. This redistribution is inhibited by Bcl-2. Recombinant caspase-2 and -9 suffice to provoke full-blown apoptosis upon microinjection into cells. Altogether, these data suggest that caspase-2 and -9 zymogens are essentially localized in mitochondria and that the disruption of the outer mitochondrial membrane occurring early during apoptosis may be critical for their subcellular redistribution and activation
Zinc and water intake in rats: investigation of adrenergic and opiatergic central mechanisms
- …