1,046 research outputs found
ON THE SPECTRAL HAUSDORFF DIMENSION OF 1D DISCRETE SCHRÖDINGER OPERATORS UNDER POWER DECAYING PERTURBATIONS
Generic Model Refactorings
Many modeling languages share some common concepts and principles. For example, Java, MOF, and UML share some aspects of the concepts\ud
of classes, methods, attributes, and inheritance. However, model\ud
transformations such as refactorings specified for a given language\ud
cannot be readily reused for another language because their related\ud
metamodels may be structurally different. Our aim is to enable a\ud
flexible reuse of model transformations across various metamodels.\ud
Thus, in this paper, we present an approach allowing the specification\ud
of generic model transformations, in particular refactorings, so\ud
that they can be applied to different metamodels. Our approach relies\ud
on two mechanisms: (1) an adaptation based mainly on the weaving\ud
of aspects; (2) the notion of model typing, an extension of object\ud
typing in the model-oriented context. We validated our approach by\ud
performing some experiments that consisted of specifying three well\ud
known refactorings (Encapsulate Field, Move Method, and Pull Up Method)\ud
and applying each of them onto three different metamodels (Java,\ud
MOF, and UML)
Behavior of the antiferromagnetic phase transition near the fermion condensation quantum phase transition in YbRh2Si2
Low-temperature specific-heat measurements on YbRh2Si2 at the second order
antiferromagnetic (AF) phase transition reveal a sharp peak at T_N=72 mK. The
corresponding critical exponent alpha turns out to be alpha=0.38, which differs
significantly from that obtained within the framework of the fluctuation theory
of second order phase transitions based on the scale invariance, where
alpha=0.1. We show that under the application of magnetic field the curve of
the second order AF phase transitions passes into a curve of the first order
ones at the tricritical point leading to a violation of the critical
universality of the fluctuation theory. This change of the phase transition is
generated by the fermion condensation quantum phase transition. Near the
tricritical point the Landau theory of second order phase transitions is
applicable and gives alpha=1/2. We demonstrate that this value of alpha is in
good agreement with the specific-heat measurements.Comment: 7 pages, 6 figures. to be published in Phys. Letters
Observational Constraints on Chaplygin Quartessence: Background Results
We derive the constraints set by several experiments on the quartessence
Chaplygin model (QCM). In this scenario, a single fluid component drives the
Universe from a nonrelativistic matter-dominated phase to an accelerated
expansion phase behaving, first, like dark matter and in a more recent epoch
like dark energy. We consider current data from SNIa experiments, statistics of
gravitational lensing, FR IIb radio galaxies, and x-ray gas mass fraction in
galaxy clusters. We investigate the constraints from this data set on flat
Chaplygin quartessence cosmologies. The observables considered here are
dependent essentially on the background geometry, and not on the specific form
of the QCM fluctuations. We obtain the confidence region on the two parameters
of the model from a combined analysis of all the above tests. We find that the
best-fit occurs close to the CDM limit (). The standard
Chaplygin quartessence () is also allowed by the data, but only at
the level.Comment: Replaced to match the published version, references update
Spatial-temporal evaluation of water quality in Brazilian semiarid Reservoirs
Reservoirs are used in the Brazilian semiarid for human supply, power generation, irrigated agriculture and
more recently, intensive fish farming, the Sobradinho reservoir being the largest of this region. In the last
decade, the semiarid region has suffered a strong drought, in opposite direction to the increasing demand
of multiple water uses. The present work aims to study the spatial-temporal variation of water quality in
two reservoirs in the Brazilian semiarid region (Sobradinho and Itaparica reservoirs). For this, samples were
collected in the dry and wet periods between 2011 and 2014, and the results were analyzed through boxplot
charts and Principal Component Analysis (PCA). For both reservoirs, our results showed that the PCAs did not
evidence a specific seasonal change in the water quality characteristics, distinguishing the wet and dry periods
through the four years studied. A clear temporal pattern was detected in both reservoirs, with higher values of
turbidity, dissolved oxygen and total phosphorus in the wet period and higher values of pH and alkalinity in the
dry period. An upstream reduction of nutrients and turbidity was not found in this study, as is reported in literature for consecutive reservoirs, probably due to the irrigation and aquaculture activities, mainly in Itaparica
reservoir
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Is cosmology consistent?
We perform a detailed analysis of the latest CMB measurements (including
BOOMERaNG, DASI, Maxima and CBI), both alone and jointly with other
cosmological data sets involving, e.g., galaxy clustering and the Lyman Alpha
Forest. We first address the question of whether the CMB data are internally
consistent once calibration and beam uncertainties are taken into account,
performing a series of statistical tests. With a few minor caveats, our answer
is yes, and we compress all data into a single set of 24 bandpowers with
associated covariance matrix and window functions. We then compute joint
constraints on the 11 parameters of the ``standard'' adiabatic inflationary
cosmological model. Out best fit model passes a series of physical consistency
checks and agrees with essentially all currently available cosmological data.
In addition to sharp constraints on the cosmic matter budget in good agreement
with those of the BOOMERaNG, DASI and Maxima teams, we obtain a heaviest
neutrino mass range 0.04-4.2 eV and the sharpest constraints to date on gravity
waves which (together with preference for a slight red-tilt) favors
``small-field'' inflation models.Comment: Replaced to match accepted PRD version. 14 pages, 12 figs. Tiny
changes due to smaller DASI & Maxima calibration errors. Expanded neutrino
and tensor discussion, added refs, typos fixed. Combined CMB data, window and
covariance matrix at http://www.hep.upenn.edu/~max/consistent.html or from
[email protected]
Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
This paper reports a measurement of D*+/- meson production in jets from
proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the
CERN Large Hadron Collider. The measurement is based on a data sample recorded
with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets
with transverse momentum between 25 and 70 GeV in the pseudorapidity range
|eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay
chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate
is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for
D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z <
1. Monte Carlo predictions fail to describe the data at small values of z, and
this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table,
matches published version in Physical Review
The origin and genetic diversity of the causal agent of Asian soybean rust, Phakopsora pachyrhizi, in South America
A sequence‐based approach was used to investigate molecular genetic variations in Phakopsora pachyrhizi, an obligate biotrophic pathogen that causes Asian soybean rust. In Argentina, the samples came from uredinium‐bearing leaves taken from 11 soybean fields; in Brazil, the samples comprised urediniospores from leaves of 10 soybean genotypes that had been grown in three experimental stations during two growing seasons. PCR‐based cloning techniques were used to generate DNA sequences for two gene regions and alignments were supplemented with data from GenBank. A total of 575 sequences for the internal transcribed spacer region (18 ribotypes) and 160 partial sequences for a housekeeping gene encoding ADP‐ribosylation factor (10 haplotypes) were obtained. Ribotype accumulation curves predicted that about 20 bacterial clones would recover 5–6 ribotypes (c. 70–80% of the total molecular variation) per locality. The samples from the three experimental stations in Brazil displayed most (14 out of 16) ribotypes found worldwide; the lack of genetic structure and differentiation at a diverse geographic scale suggests that both local and distant sources provide airborne inoculum during disease establishment. Soybean genotypes with resistance genes for the Asian soybean rust did not decrease the molecular genetic variation of fungal populations.Instituto de GenéticaFil: Jorge, V.R. Universidade Federal de Viçosa. Departamento de Bioquímica e Biologia Molecular; BrasilFil: Silva, M.R. Universidade Federal de Viçosa. Departamento de Bioquímica e Biologia Molecular; BrasilFil: Guillin, Eduardo Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética; ArgentinaFil: Freire, M.C.M. Universidade Federal de Viçosa. Departamento de Bioquímica e Biologia Molecular; BrasilFil: Schuster, I. Cooperativa Central de Pesquisa Agrícola; BrasilFil: Almeida, A.M.R. Empresa Brasileira de Pesquisa Agropecuária, Embrapa‐Soja; BrasilFil: Oliveira, Luiz O. Universidade Federal de Viçosa. Departamento de Bioquímica e Biologia Molecular; Brasi
Search for supersymmetry in final states with jets, missing transverse momentum and one isolated lepton in sqrt{s} = 7 TeV pp collisions using 1 fb-1 of ATLAS data
We present an update of a search for supersymmetry in final states containing
jets, missing transverse momentum, and one isolated electron or muon, using
1.04 fb^-1 of proton-proton collision data at sqrt{s} = 7 TeV recorded by the
ATLAS experiment at the LHC in the first half of 2011. The analysis is carried
out in four distinct signal regions with either three or four jets and
variations on the (missing) transverse momentum cuts, resulting in optimized
limits for various supersymmetry models. No excess above the standard model
background expectation is observed. Limits are set on the visible cross-section
of new physics within the kinematic requirements of the search. The results are
interpreted as limits on the parameters of the minimal supergravity framework,
limits on cross-sections of simplified models with specific squark and gluino
decay modes, and limits on parameters of a model with bilinear R-parity
violation.Comment: 18 pages plus author list (30 pages total), 9 figures, 4 tables,
final version to appear in Physical Review
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