19,942 research outputs found
Coherence stabilization of a two-qubit gate by AC fields
We consider a CNOT gate operation under the influence of quantum bit-flip
noise and demonstrate that ac fields can change bit-flip noise into phase noise
and thereby improve coherence up to several orders of magnitude while the gate
operation time remains unchanged. Within a high-frequency approximation, both
purity and fidelity of the gate operation are studied analytically. The
numerical treatment with a Bloch-Redfield master equation confirms the
analytical results.Comment: 4 pages, 2 figure
High-dimensional neutrino masses
For Majorana neutrino masses the lowest dimensional operator possible is the
Weinberg operator at . Here we discuss the possibility that neutrino
masses originate from higher dimensional operators. Specifically, we consider
all tree-level decompositions of the , and neutrino mass
operators. With renormalizable interactions only, we find 18 topologies and 66
diagrams for , and 92 topologies plus 504 diagrams at the level. At
there are already 576 topologies and 4199 diagrams. However, among all
these there are only very few genuine neutrino mass models: At we
find only (2,2,2) genuine diagrams and a total of (2,2,6) models. Here, a model
is considered genuine at level if it automatically forbids lower order
neutrino masses {\em without} the use of additional symmetries. We also briefly
discuss how neutrino masses and angles can be easily fitted in these
high-dimensional models.Comment: Coincides with published version in JHE
Impacts of in vivo and in vitro exposures to tamoxifen: comparative effects on human cells and marine organisms
Tamoxifen (TAM) is a first generation-SERM administered for hormone receptor-positive (HER+) breast cancer in both pre- and post-menopausal patients and may undergo metabolic activation in organisms that share similar receptors and thus face comparable mechanisms of response. The present study aimed to assess whether environmental trace concentrations of TAM are bioavailable to the filter feeder M. galloprovincialis (100 ng L-1) and to the deposit feeder N. diversicolor (0.5, 10, 25 and 100 ng L-1) after 14 days of exposure. Behavioural impairment (burrowing kinetic), neurotoxicity (AChE activity), endocrine disruption by alkali-labile phosphate (ALP) content, oxidative stress (SOD, CAT, GPXs activities), biotransformation (GST activity), oxidative damage (LPO) and genotoxicity (DNA damage) were assessed. Moreover, this study also pertained to compare TAM cytotoxicity effects to mussels and targeted human (i.e. immortalized retinal pigment epithelium - RPE; and human transformed endothelial cells - HeLa) cell lines, in a range of concentrations from 0.5 ng L-1 to 50 μg L-1. In polychaetes N. diversicolor, TAM exerted remarkable oxidative stress and damage at the lowest concentration (0.5 ng L-1), whereas significant genotoxicity was reported at the highest exposure level (100 ng L-1). In mussels M. galloprovincialis, 100 ng L-1 TAM caused endocrine disruption in males, neurotoxicity, and an induction in GST activity and LPO byproducts in gills, corroborating in genotoxicity over the exposure days. Although cytotoxicity assays conducted with mussel haemocytes following in vivo exposure was not effective, in vitro exposure showed to be a feasible alternative, with comparable sensitivity to human cell line (HeLa).info:eu-repo/semantics/publishedVersio
Slow down of a globally neutral relativistic beam shearing the vacuum
The microphysics of relativistic collisionless sheared flows is investigated
in a configuration consisting of a globally neutral, relativistic beam
streaming through a hollow plasma/dielectric channel. We show through
multidimensional PIC simulations that this scenario excites the Mushroom
instability (MI), a transverse shear instability on the electron-scale, when
there is no overlap (no contact) between the beam and the walls of the
hollow plasma channel. The onset of the MI leads to the conversion of the
beam's kinetic energy into magnetic (and electric) field energy, effectively
slowing down a globally neutral body in the absence of contact. The
collisionless shear physics explored in this configuration may operate in
astrophysical environments, particularly in highly relativistic and supersonic
settings where macroscopic shear processes are stable
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