9,947 research outputs found
Implication of the overlap representation for modelling generalized parton distributions
Based on a field theoretically inspired model of light-cone wave functions,
we derive valence-like generalized parton distributions and their double
distributions from the wave function overlap in the parton number conserved
s-channel. The parton number changing contributions in the t-channel are
restored from duality. In our construction constraints of positivity and
polynomiality are simultaneously satisfied and it also implies a model
dependent relation between generalized parton distributions and transverse
momentum dependent parton distribution functions. The model predicts that the
t-behavior of resulting hadronic amplitudes depends on the Bjorken variable
x_Bj. We also propose an improved ansatz for double distributions that embeds
this property.Comment: 15 pages, 8 eps figure
Resistance to ceratocystis wilt (Ceratocystis fimbriata) in parents and progenies of Eucalyptus grandis x E. urophylla.
Ceratocystis wilt, caused by Ceratocystis fimbriata, is one ofthe most damaging diseases in eucalyptus plantations worldwide. Although there are resistant genotypes, the genetic basis of resistance is still poorly understood. In this paper we studied the resistance leveI by a stem inoculation experiment of genotypes of Eucalyptus grandis and E. urophylla and estimated the heritability and gains of selection in families derived from controlled interspecific crosses. In both species, highly resistant as well as highly susceptible genotypes to Ceratocystis wilt were found. Out of 21 parents assessed, twelve were resistant and nine susceptible. Estimates of individual narrow (50%) and broad (59%) sense heritability suggested a high degree of genetic control and low allelic dominance of the trait. There was great genetic variation among and within families, a fact that contributes to high heritability and genetic gain. A genetic gain in lesion size of up to -74.4 % was obtained from selection of the 50 best clones in the evaluated families, i.e., the mean lesion length in the progeny population can be reduced by 74,4%
Rotterdam Aphasia Therapy Study (RATS) - 3: " The efficacy of intensive cognitive-linguistic therapy in the acute stage of aphasia"; design of a randomised controlled trial
Background: Aphasia is a severely disabling condition occurring in 20 to 25% of stroke patients. Most patients with aphasia due to stroke receive speech and language therapy. Methodologically sound randomised controlled trials investigating the effect of specific interventions for patients with aphasia following stroke are scarce.
Screening tests for aphasia in patients with stroke: a systematic review
Aphasia has a large impact on the quality of life and adds significantly to the costs of stroke care. Early recognition of aphasia in stroke patients is important for prognostication and well-timed treatment planning. We aimed to identify available screening tests for differentiating between aphasic and non-aphasic stroke patients, and to evaluate test accuracy, reliability, and feasibility. We searched PubMed, EMbase, Web of Science, and PsycINFO for published studies on screening tests aimed at assessing aphasia in stroke patients. The reference lists of the selected articles were scan
Surface Phase Transitions Induced by Electron Mediated Adatom-Adatom Interaction
We propose that the indirect adatom-adatom interaction mediated by the
conduction electrons of a metallic surface is responsible for the
structural phase transitions
observed in Sn/Ge (111) and Pb/Ge (111). When the indirect interaction
overwhelms the local stress field imposed by the substrate registry, the system
suffers a phonon instability, resulting in a structural phase transition in the
adlayer. Our theory is capable of explaining all the salient features of the
transitions observed in
Sn/Ge (111) and Pb/Ge (111), and is in principle applicable to a wide class of
systems whose surfaces are metallic before the transition.Comment: 4 pages, 5 figure
Prova de ganho de peso de búfalos da raça Murrah em sistema de pastejo rotacionado intensivo com suplementação alimentar - variåveis produtivas.
The gas distribution in the outer regions of galaxy clusters
We present the analysis of a local (z = 0.04 - 0.2) sample of 31 galaxy
clusters with the aim of measuring the density of the X-ray emitting gas in
cluster outskirts. We compare our results with numerical simulations to set
constraints on the azimuthal symmetry and gas clumping in the outer regions of
galaxy clusters. We exploit the large field-of-view and low instrumental
background of ROSAT/PSPC to trace the density of the intracluster gas out to
the virial radius. We perform a stacking of the density profiles to detect a
signal beyond r200 and measure the typical density and scatter in cluster
outskirts. We also compute the azimuthal scatter of the profiles with respect
to the mean value to look for deviations from spherical symmetry. Finally, we
compare our average density and scatter profiles with the results of numerical
simulations. As opposed to some recent Suzaku results, and confirming previous
evidence from ROSAT and Chandra, we observe a steepening of the density
profiles beyond \sim r500. Comparing our density profiles with simulations, we
find that non-radiative runs predict too steep density profiles, whereas runs
including additional physics and/or treating gas clumping are in better
agreement with the observed gas distribution. We report for the first time the
high-confidence detection of a systematic difference between cool-core and
non-cool core clusters beyond \sim 0.3r200, which we explain by a different
distribution of the gas in the two classes. Beyond \sim r500, galaxy clusters
deviate significantly from spherical symmetry, with only little differences
between relaxed and disturbed systems. We find good agreement between the
observed and predicted scatter profiles, but only when the 1% densest clumps
are filtered out in the simulations. [Abridged]Comment: The data for the average profiles and individual clusters can be
downloaded at:
http://www.isdc.unige.ch/~deckert/newsite/The_Planck_ROSAT_project.htm
Wide-field dynamic astronomy in the near-infrared with Palomar Gattini-IR and DREAMS
There have been a dramatic increase in the number of optical and radio transient surveys due to astronomical transients such as gravitational waves and gamma ray bursts, however, there have been a limited number of wide-field infrared surveys due to narrow field-of-view and high cost of infrared cameras, we present two new wide-field near-infrared fully automated surveyors; Palomar Gattini-IR and the Dynamic REd All-sky Monitoring Survey (DREAMS). Palomar Gattini-IR, a 25 square degree J-band imager that begun science operations at Palomar Observatory, USA in October 2018; we report on survey strategy as well as telescope and observatory operations and will also providing initial science results. DREAMS is a 3.75 square degree wide-field imager that is planned for Siding Spring Observatory, Australia; we report on the current optical and mechanical design and plans to achieve on-sky results in 2020. DREAMS is on-track to be one of the first astronomical telescopes to use an Indium Galium Arsenide (InGaAs) detector and we report initial on-sky testing results for the selected detector package. DREAMS is also well placed to take advantage and provide near-infrared follow-up of the LSST
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