4,545 research outputs found
Studies of vertical wind profiles at Cape Kennedy, Florida Final report
Vertical wind profiles spectral analysis and numerical wind forecasts at Cape Kenned
Unconventional superconducting phases in a correlated two-dimensional Fermi gas of nonstandard quasiparticles: a simple model
We discuss a detailed phase diagram and other microscopic characteristics on
the applied magnetic field - temperature (H_a-T) plane for a simple model of
correlated fluid represented by a two-dimensional (2D) gas of heavy
quasiparticles with masses dependent on the spin direction and the effective
field generated by the electron correlations. The consecutive transitions
between the Bardeen-Cooper-Schrieffer (BCS) and the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phases are either continuous or
discontinuous, depending on the values of H_a and T. In the latter case, weak
metamagnetic transitions occur at the BCS-FFLO boundary. We single out two
different FFLO phases, as well as a reentrant behaviour of one of them at high
fields. The results are compared with those for ordinary Landau quasiparticles
in order to demonstrate the robustness of the FFLO states against the BCS state
for the case with spin-dependent masses (SDM). We believe that the mechanism of
FFLO stabilization by SDM is generic: other high-field low-temperature (HFLT)
superconducting phases benefit from SDM as well.Comment: 10 pages, 4 figure
Catastrophic Fermi surface reconstruction in the shape-memory alloy AuZn
AuZn undergoes a shape-memory transition at 67 K. The de Haas van Alphen
effect persists to 100 K enabling the observation of a change in the quantum
oscillation spectrum indicative of a catastrophic Fermi surface reconstruction
at the transition. Coexistence of both Fermi surfaces at low temperatures is
suggestive of an intrinsic phase separation in the bulk of the material. In
addition, a Dingle analysis reveals a sharp change in the scattering mechanism
at a threshold cyclotron radius, which we suggest to be related to the
underlying microstructure that drives the shape-memory effect.Comment: 4 pages, 4 figure
A design of experiments approach for the rapid formulation of a chemically defined medium for metabolic profiling of industrially important microbes
This is the final version. Available on open access from Public Library of Science via the DOI in this recordData Availability: All relevant data are within the manuscript and its Supporting Information files.Geobacillus thermoglucosidans DSM2542 is an industrially important microbe, however the complex nutritional requirements of Geobacilli confound metabolic engineering efforts. Previous studies have utilised semi-defined media recipes that contain complex, undefined, biologically derived nutrients which have unknown ingredients that cannot be quantified during metabolic profiling. This study used design of experiments to investigate how individual nutrients and interactions between these nutrients contribute to growth. A mathematically derived defined medium has been formulated that has been shown to robustly support growth of G. thermoglucosidans in two different environmental conditions (96-well plate and shake flask) and with a variety of lignocellulose-based carbohydrates. This enabled the catabolism of industrially relevant carbohydrates to be investigated.Shell Global Solutions BVUniversity of Exete
Experimental observation of Frohlich superconductivity in high magnetic fields
Resistivity and irreversible magnetisation data taken within the
high-magnetic-field CDWx phase of the quasi-two-dimensional organic metal
alpha-(BEDT-TTF)2KHg(SCN)4 are shown to be consistent with a field-induced
inhomogeneous superconducting phase. In-plane skin-depth measurements show that
the resistive transition on entering the CDWx phase is both isotropic and
representative of the bulk.Comment: ten pages, four figure
Cyclotron resonance in the layered perovskite superconductor Sr2RuO4
We report a detailed study of the magnetic-field-orientation dependence of
the millimetre-wave magnetoconductivity of the superconductor Sr2RuO4 We find
two harmonic series of cyclotron resonances. We assign the first, corresponding
to a quasiparticle mass of , where is the
free-electron mass, to the Fermi-surface section. We assign the second
series, which contains only odd harmonics, to cyclotron resonance of the
Fermi-surface section, yielding a quasiparticle mass of . A third, single cyclotron resonance, corresponding to a
quasiparticle mass of , is attributed to the
Fermi-surface section. In addition, we find a very strong absorption mode in
the presence of a magnetic field component parallel to the
quasi-two-dimensional planes of the sample. Its dependence on the orientation
of the magnetic field cannot be described in the context of conventional
cyclotron resonance, and the origin of this mode is not yet clear.Comment: Submitted to J. Phys. Cond. Ma
Stochastic Approach to Enantiomeric Excess Amplification and Chiral Symmetry Breaking
Stochastic aspects of chemical reaction models related to the Soai reactions
as well as to the homochirality in life are studied analytically and
numerically by the use of the master equation and random walk model. For
systems with a recycling process, a unique final probability distribution is
obtained by means of detailed balance conditions. With a nonlinear
autocatalysis the distribution has a double-peak structure, indicating the
chiral symmetry breaking. This problem is further analyzed by examining
eigenvalues and eigenfunctions of the master equation. In the case without
recycling process, final probability distributions depend on the initial
conditions. In the nonlinear autocatalytic case, time-evolution starting from a
complete achiral state leads to a final distribution which differs from that
deduced from the nonzero recycling result. This is due to the absence of the
detailed balance, and a directed random walk model is shown to give the correct
final profile. When the nonlinear autocatalysis is sufficiently strong and the
initial state is achiral, the final probability distribution has a double-peak
structure, related to the enantiomeric excess amplification. It is argued that
with autocatalyses and a very small but nonzero spontaneous production, a
single mother scenario could be a main mechanism to produce the homochirality.Comment: 25 pages, 6 figure
Spontaneous Flavor and Parity Breaking with Wilson Fermions
We discuss the phase diagram of Wilson fermions in the -- plane for
two-flavor QCD. We argue that, as originally suggested by Aoki, there is a
phase in which flavor and parity are spontaneously broken. Recent numerical
results on the spectrum of the overlap Hamiltonian have been interpreted as
evidence against Aoki's conjecture. We show that they are in fact consistent
with the presence of a flavor-parity broken ``Aoki phase''. We also show how,
as the continuum limit is approached, one can study the lattice theory using
the continuum chiral Lagrangian supplemented by additional terms proportional
to powers of the lattice spacing. We find that there are two possible phase
structures at non-zero lattice spacing: (1) there is an Aoki phase of width
with two massless Goldstone pions; (2) there is no
symmetry breaking, and all three pions have an equal non-vanishing mass of
order . Present numerical evidence suggests that the former option is
realized for Wilson fermions. Our analysis then predicts the form of the pion
masses and the flavor-parity breaking condensate within the Aoki phase. Our
analysis also applies for non-perturbatively improved Wilson fermions.Comment: 22 pages, LaTeX, 5 figures (added several references and a comment
AMSA Conference Indigenous Workshop Summary
This report summarises a two-day Indigenous Workshop at the 2022 Australian Marine Sciences Association Conference. The workshop was the seventh to be supported by the National Environmental Science Program and the most significant to date in terms of Indigenous leadership and attendance. Indigenous participants from 45 language groups joined others from government, research and non-profit agencies.
Indigenous organisations expressed a clear desire to work with government and research agencies to enable effective co-development of research, and to establish a nationally coordinated approach to Indigenous-led research and monitoring.
The two-day Indigenous workshop brought together Indigenous leaders and community members from across the nation. This was a rare occasion for Indigenous Australians to come together and provide input into two important focal areas.
1. Collaborate and strategise on the research priorities, opportunities and constraints for Indigenous participation and leadership in environmental research in Australia’s
marine and coastal regions.
2. Discuss the need for a National Indigenous Environmental Research Network
(NIERN)
Superconducting properties and Fermi-surface topology of the quasi-two-dimensional organic superconductor -(BETS)GaCl
The Fermi surface topology of the organic superconductor \lbets has been
determined using the Shubnikov-de Haas and magnetic breakdown effects and
angle-dependent magnetoresistance oscillations. The former experiments were
carried out in pulsed fields of up to 60 T, whereas the latter employed
quasistatic fields of up to 30 T. All of these data show that the Fermi-surface
topology of \lbets is very similar to that of the most heavily-studied organic
superconductor, \cuscn, except in one important respect; the interplane
transfer integral in \lbets is a factor larger than that in \cuscn .
The increased three-dimensionality of \lbets is manifested in radiofrequency
penetration-depth measurements, which show a clear dimensional crossover in the
behaviour of . The radiofrequency measurements have also been used
to extract the Labusch parameter determining the fluxoid interactions as a
function of temperature, and to map the flux-lattice melting curve.Comment: 24 pages 10 figure
- …