16,684 research outputs found
Economical Valuation of Hypothetically Constructed Washland around a Wetland
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
Search for axion-like particles using a variable baseline photon regeneration technique
We report the first results of the GammeV experiment, a search for milli-eV
mass particles with axion-like couplings to two photons. The search is
performed using a "light shining through a wall" technique where incident
photons oscillate into new weakly interacting particles that are able to pass
through the wall and subsequently regenerate back into detectable photons. The
oscillation baseline of the apparatus is variable, thus allowing probes of
different values of particle mass. We find no excess of events above background
and are able to constrain the two-photon couplings of possible new scalar
(pseudoscalar) particles to be less than 3.1x10^{-7} GeV^{-1} (3.5x10^{-7}
GeV^{-1}) in the limit of massless particles.Comment: 5 pages, 4 figures. This is the version accepted by PRL and includes
updated limit
An Experimental Platform for Pulsed-Power Driven Magnetic Reconnection
We describe a versatile pulsed-power driven platform for magnetic
reconnection experiments, based on exploding wire arrays driven in parallel
[Suttle, L. G. et al. PRL, 116, 225001]. This platform produces inherently
magnetised plasma flows for the duration of the generator current pulse (250
ns), resulting in a long-lasting reconnection layer. The layer exists for long
enough to allow evolution of complex processes such as plasmoid formation and
movement to be diagnosed by a suite of high spatial and temporal resolution
laser-based diagnostics. We can access a wide range of magnetic reconnection
regimes by changing the wire material or moving the electrodes inside the wire
arrays. We present results with aluminium and carbon wires, in which the
parameters of the inflows and the layer which forms are significantly
different. By moving the electrodes inside the wire arrays, we change how
strongly the inflows are driven. This enables us to study both symmetric
reconnection in a range of different regimes, and asymmetric reconnection.Comment: 14 pages, 9 figures. Version revised to include referee's comments.
Submitted to Physics of Plasma
An integrable multicomponent quad equation and its Lagrangian formulation
We present a hierarchy of discrete systems whose first members are the
lattice modified Korteweg-de Vries equation, and the lattice modified
Boussinesq equation. The N-th member in the hierarchy is an N-component system
defined on an elementary plaquette in the 2-dimensional lattice. The system is
multidimensionally consistent and a Lagrangian which respects this feature,
i.e., which has the desirable closure property, is obtained.Comment: 10 page
Axions and the Strong CP Problem
Current upper bounds of the neutron electric dipole moment constrain the
physically observable quantum chromodynamic (QCD) vacuum angle . Since QCD explains vast experimental data from the 100 MeV
scale to the TeV scale, it is better to explain this smallness of
in the QCD framework, which is the strong \Ca\Pa problem. Now,
there exist two plausible solutions to this problem, one of which leads to the
existence of the very light axion. The axion decay constant window, $10^9\
{\gev}\lesssim F_a\lesssim 10^{12} \gev{\cal O}(1)\theta_1F_a\gtrsim 10^{12}\theta_1<{\cal O}(1)$,
axions may constitute a significant fraction of dark matter of the universe.
The supersymmetrized axion solution of the strong \Ca\Pa problem introduces its
superpartner the axino which might have affected the universe evolution
significantly. Here, we review the very light axion (theory,
supersymmetrization, and models) with the most recent particle, astrophysical
and cosmological data, and present prospects for its discovery.Comment: 47 pages with 32 figure
The Mre11-Rad50-Nbs1 complex mediates activation of TopBP1 by ATM
The activation of ATR-ATRIP in response to double-stranded DNA breaks (DSBs) depends upon ATM in human cells and Xenopus egg extracts. One important aspect of this dependency involves regulation of TopBP1 by ATM. In Xenopus egg extracts, ATM associates with TopBP1 and thereupon phosphorylates it on S1131. This phosphorylation enhances the capacity of TopBP1 to activate the ATR-ATRIP complex. We show that TopBP1 also interacts with the Mre11-Rad50-Nbs1 (MRN) complex in egg extracts in a checkpoint-regulated manner. This interaction involves the Nbs1 subunit of the complex. ATM can no longer interact with TopBP1 in Nbs1-depleted egg extracts, which suggests that the MRN complex helps to bridge ATM and TopBP1 together. The association between TopBP1 and Nbs1 involves the first pair of BRCT repeats in TopBP1. In addition, the two tandem BRCT repeats of Nbs1 are required for this binding. Functional studies with mutated forms of TopBP1 and Nbs1 suggested that the BRCT-dependent association of these proteins is critical for a normal checkpoint response to DSBs. These findings suggest that the MRN complex is a crucial mediator in the process whereby ATM promotes the TopBP1-dependent activation of ATR-ATRIP in response to DSBs
Cell type-specific modulation of sensory and affective components of itch in the periaqueductal gray
Observation of the Dependence of Scintillation from Nuclear Recoils in Liquid Argon on Drift Field
We have exposed a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC)
to a low energy pulsed narrowband neutron beam, produced at the Notre Dame
Institute for Structure and Nuclear Astrophysics to study the scintillation
light yield of recoiling nuclei in a LAr-TPC. A liquid scintillation counter
was arranged to detect and identify neutrons scattered in the LAr-TPC target
and to select the energy of the recoiling nuclei.
We report the observation of a significant dependence on drift field of
liquid argon scintillation from nuclear recoils of 11 keV. This observation is
important because, to date, estimates of the sensitivity of noble liquid TPC
dark matter searches are based on the assumption that electric field has only a
small effect on the light yield from nuclear recoils.Comment: v3 updated to reflect published version, including a set of plots for
49.9 keV dat
Spin-parity dependent tunneling of magnetization in single-molecule magnets
Single-molecule magnets facilitate the study of quantum tunneling of
magnetization at the mesoscopic level. The spin-parity effect is among the
fundamental predictions that have yet to be clearly observed. It is predicted
that quantum tunneling is suppressed at zero transverse field if the total spin
of the magnetic system is half-integer (Kramers degeneracy) but is allowed in
integer spin systems. The Landau-Zener method is used to measure the tunnel
splitting as a function of transverse field. Spin-parity dependent tunneling is
established by comparing the transverse field dependence of the tunnel
splitting of integer and half-integer spin systems.Comment: 4 pages, 6 figure
Time evolution of the Rabi Hamiltonian from the unexcited vacuum
The Rabi Hamiltonian describes a single mode of electromagnetic radiation
interacting with a two-level atom. Using the coupled cluster method, we
investigate the time evolution of this system from an initially empty field
mode and an unexcited atom. We give results for the atomic inversion and field
occupation, and find that the virtual processes cause the field to be squeezed.
No anti-bunching occurs.Comment: 25 pages, 8 figures, RevTe
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