3,909 research outputs found
Stochastic Background of Gravitational Waves from Fermions
5 pages, 1 figurePreheating and other particle production phenomena in the early Universe can give rise to high- energy out-of-equilibrium fermions with an anisotropic stress. We develop a formalism to calculate the spectrum of gravitational waves due to fermions, and apply it to a variety of scenarios after inflation. We pay particular attention to regularization issues. We show that fermion production sources a stochastic background of gravitational waves with a significant amplitude, but we find that typical frequencies of this new background are not within the presently accessible direct detec- tion range. However, small-coupling scenarios might still produce a signal observable by planned detectors, and thus open a new window into the physics of the very early Universe.Peer reviewe
Reference-Plane Invariant Method for Measuring Electromagnetic Parameters of Materials
This paper presents a simple and effective wideband method for the
determination of material properties, such as the complex index of refraction
and the complex permittivity and permeability. The method is explicit
(non-iterative) and reference-plane invariant: it uses a certain combination of
scattering parameters in conjunction with group-velocity data. This technique
can be used to characterize both dielectric and magnetic materials. The
proposed method is verified experimentally within a frequency range between 2
to 18 GHz on polytetrafluoroethylene and polyvinylchloride samples. A
comprehensive error and stability analysis reveals that, similar to other
methods based on transmission/reflection measurement, the uncertainties are
larger at low frequencies and at the Fabry-Perot resonances.Comment: 12 pages, 21 figure
CONSUMERS' WILLINGNESS TO PAY FOR THE COLOR OF SALMON:A CHOICE EXPERIMENT WITH REAL ECONOMIC INCENTIVES
We designed an experimental market with posted prices to investigate consumers' willingness to pay for the color of salmon. Salmon fillets varying in color and price were displayed in 20 choice scenarios. In each scenario, the participants chose which of two salmon fillets they wanted to buy. To induce real economic incentives, each participant drew one unique binding scenario; the participants then had to buy the salmon fillet they had chosen in their binding scenario.Consumer/Household Economics,
Fluctuations along supersymmetric flat directions during Inflation
We consider a set of scalar fields, consisting of a single flat direction and
one or several non-flat directions. We take our cue from the MSSM, considering
separately D-flat and F-flat directions, but our results apply to any
supersymmetric scenario containing flat directions. We study the field
fluctuations during pure de Sitter Inflation, following the evolution of the
infrared modes by numerically solving the appropriate Langevin equations. We
demonstrate that for the Standard Model U(1), SU(2) or SU(3) gauge couplings,
as well as for large enough Yukawa couplings, the fluctuations along the
non-flat directions effectively block the fluctuations along the flat
directions. The usual expected behaviour \propto N, with N the
number of efolds, may be strongly violated, depending on the coupling
strengths. As a consequence, those cosmological considerations, which are
derived assuming that during inflation flat directions fluctuate freely, should
be revised.Comment: 19 pages, 5 figures, Submitted to JCA
Management of an Accessory Bile Duct Leak Following Pancreaticoduodenectomy: A Novel Approach Utilizing a Percutaneous and Endoscopic Rendezvous.
Biliary leaks are uncommon but morbid complications of pancreaticoduodenectomies, which have historically been managed with percutaneous drainage, reoperation, or a combination of both. We report a de novo percutaneous-endoscopic hepaticojejunostomy from an anomalous right hepatic duct injured during pancreaticoduodenectomy to the afferent bowel limb. The percutaneous-endoscopic hepaticojejunostomy was stented to allow for tract formation with successful stent removal after 5.5 months. One year after the creation of the percutaneous-endoscopic hepaticojejunostomy, the patient remains clinically well without evidence of biliary leak or obstruction
Applying causality principles to the axiomatization of probabilistic cellular automata
Cellular automata (CA) consist of an array of identical cells, each of which
may take one of a finite number of possible states. The entire array evolves in
discrete time steps by iterating a global evolution G. Further, this global
evolution G is required to be shift-invariant (it acts the same everywhere) and
causal (information cannot be transmitted faster than some fixed number of
cells per time step). At least in the classical, reversible and quantum cases,
these two top-down axiomatic conditions are sufficient to entail more
bottom-up, operational descriptions of G. We investigate whether the same is
true in the probabilistic case. Keywords: Characterization, noise, Markov
process, stochastic Einstein locality, screening-off, common cause principle,
non-signalling, Multi-party non-local box.Comment: 13 pages, 6 figures, LaTeX, v2: refs adde
Human transcription factor and protein kinase gene fusions in human cancer
Oncogenic gene fusions are estimated to account for up-to 20% of cancer morbidity. Recently sequence-level studies have established oncofusions throughout all tissue types. However, the functional implications of the identified oncofusions have often not been investigated. In this study, identified oncofusions from a fusion detection approach (DEEPEST) were analyzed in detail. Of the 28,863 oncofusions, we found almost 30% are expected to produce functional proteins with features from both parent genes. Kinases and transcription factors were the main gene families of the protein producing fusions. Considering their role as initiators, actors, and termination points of cellular signaling pathways, we focused our in-depth analyses on them. Domain architecture of the fusions and their wild-type interactors suggests that abnormal molecular context of protein domains caused by fusion events may unlock the oncogenic potential of the wild type counterparts of the fusion proteins. To understand overall oncofusion effects, we performed differential expression analysis using TCGA cancer project samples. Results indicated oncofusion-specific alterations in gene expression levels, and lower expression levels of components of key cellular pathways, in particular signal transduction and transcription regulation. The sum of results suggests that kinase and transcription factor oncofusions deregulate cellular signaling, possibly via acquiring novel functions.Peer reviewe
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