100 research outputs found
Off-center coherent-state representation and an application to semiclassics
By using the overcompleteness of coherent states we find an alternative form
of the unit operator for which the ket and the bra appearing under the
integration sign do not refer to the same phase-space point. This defines a new
quantum representation in terms of Bargmann functions, whose basic features are
presented. A continuous family of secondary reproducing kernels for the
Bargmann functions is obtained, showing that this quantity is not necessarily
unique for representations based on overcomplete sets. We illustrate the
applicability of the presented results by deriving a semiclassical expression
for the Feynman propagator that generalizes the well-known van Vleck formula
and seems to point a way to cope with long-standing problems in semiclassical
propagation of localized states
The brittle-ductile transition in active volcanoes
Abstract Contrasting deformation mechanisms precede volcanic eruptions and control precursory signals. Density increase and high uplifts consistent with magma intrusion and pressurization are in contrast with dilatant responses and reduced surface uplifts observed before eruptions. We investigate the impact that the rheology of rocks constituting the volcanic edifice has on the deformation mechanisms preceding eruptions. We propose a model for the pressure and temperature dependent brittle-ductile transition through which we build a strength profile of the shallow crust in two idealized volcanic settings (igneous and sedimentary basement). We have performed finite element analyses in coupled thermo-hydro-mechanical conditions to investigate the influence of static diking on the local brittle-ductile transition. Our results show that in active volcanoes: (i) dilatancy is an appropriate indicator for the brittle-ductile transition; (ii) the predicted depth of the brittle-ductile transition agrees with the observed attenuated seismicity; (iii) seismicity associated with diking is likely to be affected by ductile deformation mode caused by the local temperature increase; (iv) if failure occurs within the edifice, it is likely to be brittle-dilatant with strength and stiffness reduction that blocks stress transfers within the volcanic edifice, ultimately damping surface uplifts
On Bargmann Representations of Wigner Function
By using the localized character of canonical coherent states, we give a
straightforward derivation of the Bargmann integral representation of Wigner
function (W). A non-integral representation is presented in terms of a
quadratic form V*FV, where F is a self-adjoint matrix whose entries are
tabulated functions and V is a vector depending in a simple recursive way on
the derivatives of the Bargmann function. Such a representation may be of use
in numerical computations. We discuss a relation involving the geometry of
Wigner function and the spacial uncertainty of the coherent state basis we use
to represent it.Comment: accepted for publication in J. Phys. A: Math. and Theo
Analytical approach to viscous fingering in a cylindrical Hele-Shaw cell
We report analytical results for the development of the viscous fingering
instability in a cylindrical Hele-Shaw cell of radius a and thickness b. We
derive a generalized version of Darcy's law in such cylindrical background, and
find it recovers the usual Darcy's law for flow in flat, rectangular cells,
with corrections of higher order in b/a. We focus our interest on the influence
of cell's radius of curvature on the instability characteristics. Linear and
slightly nonlinear flow regimes are studied through a mode-coupling analysis.
Our analytical results reveal that linear growth rates and finger competition
are inhibited for increasingly larger radius of curvature. The absence of
tip-splitting events in cylindrical cells is also discussed.Comment: 14 pages, 3 ps figures, Revte
Survey on the Bell nonlocality of a pair of entangled qudits
The question of how Bell nonlocality behaves in bipartite systems of higher
dimensions is addressed. By employing the probability of violation of local
realism under random measurements as the figure of merit, we investigate the
nonlocality of entangled qudits with dimensions ranging from to . We
proceed in two complementary directions. First, we study the specific Bell
scenario defined by the Collins-Gisin-Linden-Massar-Popescu (CGLMP) inequality.
Second, we consider the nonlocality of the same states under a more general
perspective, by directly addressing the space of joint probabilities (computing
the frequencies of behaviours outside the local polytope). In both approaches
we find that the nonlocality decreases as the dimension grows, but in quite
distinct ways. While the drop in the probability of violation is exponential in
the CGLMP scenario, it presents, at most, a linear decay in the space of
behaviours. Furthermore, in both cases the states that produce maximal numeric
violations in the CGLMP inequality present low probabilities of violation in
comparison with maximally entangled states, so, no anomaly is observed.
Finally, the nonlocality of states with non-maximal Schmidt rank is
investigated.Comment: 8 pages, 6 figures, 2 table
Global physics-based database of injection-induced seismicity
Fluid injection into geological formations for energy
resource development frequently induces (micro)seismicity. Moderate- to
large-magnitude induced earthquakes may cause injuries and/or economic loss,
with the consequence of jeopardizing the operation and future development of
these geo-energy projects. To achieve an improved understanding of the
mechanisms of induced seismicity, develop forecasting tools and manage the
associated risks, it is necessary to carefully examine seismic data from
reported cases of induced seismicity and the parameters controlling them.
However, these data are challenging to gather together and are
time-consuming to collate as they come from different disciplines and
sources. Here, we present a publicly available, multi-physical database of
injection-induced seismicity (Kivi et al., 2022a;
https://doi.org/10.20350/digitalCSIC/14813), sourced from an extensive
review of published documents. Currently, it contains 158 datasets of
induced seismicity caused by various subsurface energy-related applications
worldwide. Each dataset covers a wide range of variables, delineating
general site information, host rock properties, in situ geologic and
tectonic conditions, fault characteristics, conducted field operations, and
recorded seismic activities. We publish the database in flat-file formats
(i.e., .xls and .csv tables) to facilitate its dissemination and utilization
by geoscientists while keeping it directly readable by computer codes for
convenient data manipulation. The multi-disciplinary content of this
database adds unique value to databases focusing only on seismicity data. In
particular, the collected data aim at facilitating the understanding of the
spatiotemporal occurrence of induced earthquakes, the diagnosis of
potential triggering mechanisms, and the development of scaling relations of
maximum possible earthquake magnitudes and operational parameters. The
database will boost research in seismic hazard forecasting and mitigation,
paving the way for increasing contributions of geo-energy resources to
meeting net-zero carbon emissions.</p
A conjugate for the Bargmann representation
In the Bargmann representation of quantum mechanics, physical states are
mapped into entire functions of a complex variable z*, whereas the creation and
annihilation operators and play the role of
multiplication and differentiation with respect to z*, respectively. In this
paper we propose an alternative representation of quantum states, conjugate to
the Bargmann representation, where the roles of and
are reversed, much like the roles of the position and momentum operators in
their respective representations. We derive expressions for the inner product
that maintain the usual notion of distance between states in the Hilbert space.
Applications to simple systems and to the calculation of semiclassical
propagators are presented.Comment: 15 page
The quantum state vector in phase space and Gabor's windowed Fourier transform
Representations of quantum state vectors by complex phase space amplitudes,
complementing the description of the density operator by the Wigner function,
have been defined by applying the Weyl-Wigner transform to dyadic operators,
linear in the state vector and anti-linear in a fixed `window state vector'.
Here aspects of this construction are explored, with emphasis on the connection
with Gabor's `windowed Fourier transform'. The amplitudes that arise for simple
quantum states from various choices of window are presented as illustrations.
Generalized Bargmann representations of the state vector appear as special
cases, associated with Gaussian windows. For every choice of window, amplitudes
lie in a corresponding linear subspace of square-integrable functions on phase
space. A generalized Born interpretation of amplitudes is described, with both
the Wigner function and a generalized Husimi function appearing as quantities
linear in an amplitude and anti-linear in its complex conjugate.
Schr\"odinger's time-dependent and time-independent equations are represented
on phase space amplitudes, and their solutions described in simple cases.Comment: 36 pages, 6 figures. Revised in light of referees' comments, and
further references adde
Esbl/ampc-producing escherichia coli in wild boar: Epidemiology and risk factors
The complex health problem of antimicrobial resistance (AMR) involves many host species, numerous bacteria and several routes of transmission. Extended-spectrum β-lactamase and AmpC (ESBL/AmpC)-producing Escherichia coli are among the most important strains. Moreover, wildlife hosts are of interest as they are likely antibiotics free and are assumed as environmental indicators of AMR contamination. Particularly, wild boar (Sus scrofa) deserves attention because of its increased population densities, with consequent health risks at the wildlife–domestic–human interface, and the limited data available on AMR. Here, 1504 wild boar fecal samples were microbiologically and molecularly analyzed to investigate ESBL/AmpC-producing E. coli and, through generalized linear models, the effects of host-related factors and of human population density on their spread. A prevalence of 15.96% of ESBL/AmpC-producing E. coli, supported by blaCTX-M (12.3%), blaTEM (6.98%), blaCMY (0.86%) and blaSHV (0.47%) gene detection, emerged. Young animals were more colonized by ESBL/AmpC strains than older subjects, as observed in domestic animals. Increased human population density leads to increased blaTEM prevalence in wild boar, suggesting that spatial overlap may favor this transmission. Our results show a high level of AMR contamination in the study area that should be further investigated. However, a role of wild boar as a maintenance host of AMR strains emerged
Efficient Operation of Modular Grid-Connected Battery Inverters for RES Integration
Grid-connected battery storage systems on megawatt-scale play an important role for the integration of renewable energies into electricity markets and grids. In reality, these systems consist of several batteries and inverters, which have a lower energy conversion efficiency in partial load operation. In renewable energy sources (RES) applications, however, battery systems are often operated at low power. The modularity of grid-connected battery storage systems thus allows improving system efficiency during operation. This contribution aims at quantifying the effect of segmenting the system into multiple battery-inverter subsystems on reducing operating losses. The analysis is based on a mixed-integer linear program that determines the system operation by minimizing operating losses. The analysis shows that systems with high modularity can meet a given schedule with lower losses. Increasing modularity from one to 32 subsystems can reduce operating losses by almost 40%. As the number of subsystems increases, the benefit of higher efficiency decreases. The resulting state of charge (SOC) pattern of the batteries is similar for the investigated systems, while the average SOC value is higher in highly modular systems
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