8,345 research outputs found
The Impact of Prescribed Fire on Moth Assemblages in the Boston Mountains and Ozark Highlands, in Arkansas
In addition to the impacts of prescribed fires on forest vegetation, this ecosystem process also has dramatic impacts on associated insect assemblages. For herbivorous, terrestrial insects, fire predictably results in a cycle of initial insect population reduction followed by recovery and growth, in which these insect populations exceed pre-fire abundances. We sought to examine if fire-induced disturbance cycles make prescribed burned areas more or less suitable specifically for moths (order Lepidoptera), which is a major food source for, among others, multiple bat species. We surveyed moth assemblages at 20 burned and 20 unburned sites in the Boston Mountain and Ozark Highland ecoregions of Arkansas, to determine if biomass or abundance of moths differed between areas that had been burned in the past 10 years, and those areas that had never been burned. Samples were collected early (April to July) and late (August to November) in the growing season of 2017 (hereafter early season and late season, respectively). We compared biomass and abundance of all moths, and of five representative moth species, between burned and unburned sites. The five moth species were chosen and considered to be representative due to their high relative abundance, and ease of identification. The five chosen moth species included the banded tussock moth (Halysidota tessellaris), white-dotted prominent moth (Nadata gibbosa), ailanthus moth (Atteva aurea), grape leaffolder (Desmia funeralis), and painted lichen moth (Hypoprepia fucosa). Results from paired t-tests showed no significant difference in total biomass, or abundance of representative species between burned and unburned sites. However, generalized linear regression models showed significantly higher abundance of moths in areas with high basal area that had been previously burned (β = -0.038 ± 0.004 SE,
Warm dark matter sterile neutrinos in electron capture and beta decay spectra
We briefly review the motivation to search for sterile neutrinos in the keV
mass scale, as dark matter candidates, and the prospects to find them in beta
decay or electron capture spectra, with a global perspective. We describe the
fundamentals of the neutrino flavor-mass eigenstate mismatch that opens the
possibility of detecting sterile neutrinos in such ordinary nuclear processes.
Results are shown and discussed for the effect of heavy neutrino emission in
electron capture in Holmium 163 and in two isotopes of Lead, 202 and 205, as
well as in the beta decay of Tritium. We study the de-excitation spectrum in
the considered cases of electron capture and the charged lepton spectrum in the
case of Tritium beta decay. For each of these cases, we define ratios of
integrated transition rates over different regions of the spectrum under study,
and give new results that may guide and facilitate the analysis of possible
future measurements, paying particular attention to forbidden transitions in
Lead isotopes.Comment: 13 pages, 4 figures, 2 table
Spin Glass Computations and Ruelle's Probability Cascades
We study the Parisi functional, appearing in the Parisi formula for the
pressure of the SK model, as a functional on Ruelle's Probability Cascades
(RPC). Computation techniques for the RPC formulation of the functional are
developed. They are used to derive continuity and monotonicity properties of
the functional retrieving a theorem of Guerra. We also detail the connection
between the Aizenman-Sims-Starr variational principle and the Parisi formula.
As a final application of the techniques, we rederive the Almeida-Thouless line
in the spirit of Toninelli but relying on the RPC structure.Comment: 20 page
Ground-state properties and symmetry energy of neutron-rich and neutron-deficient Mg isotopes
A comprehensive study of various ground-state properties of neutron-rich and
neutron-deficient Mg isotopes with =20-36 is performed in the framework of
the self-consistent deformed Skyrme-Hartree-Fock plus BCS method. The
correlation between the skin thickness and the characteristics related with the
density dependence of the nuclear symmetry energy is investigated for this
isotopic chain following the theoretical approach based on the coherent density
fluctuation model and using the Brueckner energy-density functional. The
results of the calculations show that the behavior of the nuclear charge radii
and the nuclear symmetry energy in the Mg isotopic chain is closely related to
the nuclear deformation. We also study, within our theoretical scheme, the
emergence of an "island of inversion" at neutron-rich Mg nucleus, that
was recently proposed from the analyses of spectroscopic measurements of
Mg low-lying energy spectrum and the charge rms radii of all magnesium
isotopes in the shell.Comment: 13 pages, 13 figures, to be published in Physical Review
Testing M2T/T2M Transformations
Presentado en: 16th International Conference on Model Driven Engineering Languages and Systems (MODELS 2013). Del 29 de septiembre al 4 de octubre. Miami, EEUU.Testing model-to-model (M2M) transformations is becoming a prominent topic in the current Model-driven Engineering landscape. Current approaches for transformation testing, however, assume having explicit model representations for the input domain and for the output domain of the transformation. This excludes other important transformation kinds, such as model-to-text (M2T) and text-to-model (T2M) transformations, from being properly tested since adequate model representations are missing either for the input domain or for the output domain. The contribution of this paper to overcome this gap is extending Tracts, a M2M transformation testing approach, for M2T/T2M transformation testing. The main mechanism we employ for reusing Tracts is to represent text within a generic metamodel. By this, we transform the M2T/T2M transformation specification problems into equivalent M2M transformation specification problems. We demonstrate the applicability of the approach by two examples and present how the approach is implemented for the Eclipse Modeling Framework (EMF). Finally, we apply the approach to evaluate code generation capabilities of several existing UML tools.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Proyecto TIN2011-2379
The generalized Fenyes-Nelson model for free scalar field theory
The generalized Fenyes--Nelson model of quantum mechanics is applied to the
free scalar field. The resulting Markov field is equivalent to the Euclidean
Markov field with the times scaled by a common factor which depends on the
diffusion parameter. This result is consistent between Guerra's earlier work on
stochastic quantization of scalar fields. It suggests a deep connection between
Euclidean field theory and the stochastic interpretation of quantum mechanics.
The question of Lorentz covariance is also discussed.Comment: 6 page
AB responses: from bare nucleons to complex nuclei
We study the occurrence of factorization in polarized and unpolarized
observables in coincidence quasi-elastic electron scattering. Starting with the
relativistic distorted wave impulse approximation, we reformulate the effective
momentum approximation and show that the latter leads to observables which
factorize under some specific conditions. Within this framework, the role
played by final state interactions and, in particular, by the spin-orbit term
is explored. Connection with the nonrelativistic formalism is studied in depth.
Numerical results are presented to illustrate the analytical derivations and to
quantify the differences between factorized and unfactorized approaches.Comment: 26 pages, 5 figures. Improved and extended version. To be published
in Phys. Rev.
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