9,385 research outputs found
SIR-A imagery in geologic studies of the Sierra Madre Oriental, northeastern Mexico. Part 1 (Regional stratigraphy): The use of morphostratigraphic units in remote sensing mapping
SIR-A imaging was used in geological studies of sedimentary terrains in the Sierra Madre Oriental, northeastern Mexico. Geological features such as regional strike and dip, bedding, folding and faulting were readily detected on the image. The recognition of morphostructural units in the imagery, coupled with field verification, enabled geological mapping of the region at the scale of 1:250 000. Structural profiling lead to the elaboration of a morphostructural map allowing the recognition of an echelon folds and field trends which were used to postulate the ectonic setting of the region
Linear second-order differential equations for barotropic FRW cosmologies
"Simple linear second-order differential equations have been written down for FRW cosmologies with barotropic fluids by Faraoni. His results have been extended by Rosu, who employed techniques belonging to nonrelativistic supersymmetry to obtain time-dependent adiabatic indices. Further extensions are presented here using the known connection between the linear second-order differential equations and Dirac-like equations in the same supersymmetric context. These extensions are equivalent to adding an imaginary part to the adiabatic index which is proportional to the mass parameter of the Dirac spinor. The natural physical interpretation of the imaginary part is related to the particular dissipation and instabilities of the barotropic FRW hydrodynamics that are introduced by means of this supersymmetric scheme.
Use of Supplements for Increasing Performances of Suckling Martinik Ewes When Fed Tropical Forages
Experiments have been carried out to determine the effects of supplementation upon milk production and growing performances with hair sheep Martinik ewes weighing 48 ± 4 kg liveweight (LW). In a first trial, 6 single bearing ewes (group GS) were offered individually a daily 0.5 kg of commercial pellets. They were compared to the control group (GN; 6 ewes) with no supplement during 10 weeks of lactation. Basal diet was chopped Digitaria decumbens grass ad libitum. In a second trial, level of supplementation was adapted to the ewes’ litter size: 6 twins bearing ewes (TW) and 6 single (SI). Mean milk production (oxytocin method) reached 1186 and 940 g.d-1 (P\u3c 0.05) for GS and GN ewes, respectively. Body condition score (BCS) of GS ewes maintained during lactation while those of GN ewes slightly decreased (P\u3c 0.05). No difference was recorded for lambs daily weight gain (DWG). Milk production varied significantly (P\u3c 0.05) according to the litter size: 926 and 1246 g.d-1 for SI and TW, respectively. The BCS of TW ewes decreased more than those of SI ewes (-1.4 vs –1.0). Individual DWG were different (P\u3c 0.01): 216 and 150 g.d-1 for single and twin lamb, respectively. It is concluded that use of supplements is necessary in intensive breeding conditions (high reproduction frequency and productivity), in order to allow high levels of performances when ewes are fed tropical forages
Scalar conservation laws with nonconstant coefficients with application to particle size segregation in granular flow
Granular materials will segregate by particle size when subjected to shear,
as occurs, for example, in avalanches. The evolution of a bidisperse mixture of
particles can be modeled by a nonlinear first order partial differential
equation, provided the shear (or velocity) is a known function of position.
While avalanche-driven shear is approximately uniform in depth, boundary-driven
shear typically creates a shear band with a nonlinear velocity profile. In this
paper, we measure a velocity profile from experimental data and solve initial
value problems that mimic the segregation observed in the experiment, thereby
verifying the value of the continuum model. To simplify the analysis, we
consider only one-dimensional configurations, in which a layer of small
particles is placed above a layer of large particles within an annular shear
cell and is sheared for arbitrarily long times. We fit the measured velocity
profile to both an exponential function of depth and a piecewise linear
function which separates the shear band from the rest of the material. Each
solution of the initial value problem is non-standard, involving curved
characteristics in the exponential case, and a material interface with a jump
in characteristic speed in the piecewise linear case
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Results of the ontology alignment evaluation initiative 2019
The Ontology Alignment Evaluation Initiative (OAEI) aims at comparing ontology matching systems on precisely defined test cases. These test cases can be based on ontologies of different levels of complexity (from simple thesauri to expressive OWL ontologies) and use different evaluation modalities (e.g., blind evaluation, open evaluation, or consensus). The OAEI 2019 campaign offered 11 tracks with 29 test cases, and was attended by 20 participants. This paper is an overall presentation of that campaign
Constraining the expansion rate of the Universe using low-redshift ellipticals as cosmic chronometers
We present a new methodology to determine the expansion history of the
Universe analyzing the spectral properties of early type galaxies (ETG). We
found that for these galaxies the 4000\AA break is a spectral feature that
correlates with the relative ages of ETGs. In this paper we describe the
method, explore its robustness using theoretical synthetic stellar population
models, and apply it using a SDSS sample of 14 000 ETGs. Our motivation
to look for a new technique has been to minimise the dependence of the cosmic
chronometer method on systematic errors. In particular, as a test of our
method, we derive the value of the Hubble constant (stat)
(syst) (68% confidence), which is not only fully compatible with the
value derived from the Hubble key project, but also with a comparable error
budget. Using the SDSS, we also derive, assuming w=constant, a value for the
dark energy equation of state parameter (stat)
(syst). Given the fact that the SDSS ETG sample only reaches , this
result shows the potential of the method. In future papers we will present
results using the high-redshift universe, to yield a determination of H(z) up
to .Comment: 25 pages, 17 figures, JCAP accepte
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Evaluating Ontology Matching Systems on Large, Multilingual and Real-world Test Cases
In the field of ontology matching, the most systematic evaluation of matching systems is established by the Ontology Alignment Evaluation Initiative (OAEI), which is an annual campaign for evaluating ontology matching systems organized by different groups of researchers. In this paper, we report on the results of an intermediary OAEI campaign called OAEI 2011.5. The evaluations of this campaign are divided in five tracks. Three of these tracks are new or have been improved compared to previous OAEI campaigns. Overall, we evaluated 18 matching systems. We discuss lessons learned, in terms of scalability, multilingual issues and the ability do deal with real world cases from different domains
The Photometric and Kinematic Structure of Face-On Disk Galaxies. I. Sample Definition, H-alpha Integral Field Spectroscopy, and HI Line-Widths
We present a survey of the photometric and kinematic properties of 39 nearby,
nearly face-on disk galaxies. Our approach exploits echelle-resolution
integral-field spectroscopy of the H-alpha regions, obtained with DensePak on
the WIYN 3.5m telescope Bench Spectrograph. This data is complemented by HI
line-profiles observed with the Nancay radio telescope for 25 of these sample
galaxies. Twelve additional line-widths are available for sample galaxies from
the literature. In this paper, we introduce the goals of this survey, define
the sample selection algorithm, and amass the integral field spectroscopic data
and HI line-widths. We establish spatially-integrated H-alpha line-widths for
the sample. We test the veracity of these spatially-integrated line profiles by
convolving narrow-band imaging data with velocity field information for one of
the sample galaxies, PGC 38268, and also by comparing to HI line profiles. We
find HI and H-alpha line profiles to be similar in width but different in
shape, indicating we are observing different spatial distributions of ionized
and neutral gas in largely axisymmetric systems with flat outer
rotation-curves. We also find vertical velocity dispersions of the ionized disk
gas within several disk scale-lengths have a median value of 18 km/s and an 80%
range of 12-26 km/s. This is only a factor of ~2 larger than what is observed
for neutral atomic and molecular gas. With standard assumptions for intrinsic
and thermal broadening for H-alpha, this translates into a factor of three
range in turbulent velocities, between 8 and 25 km/s.Comment: 29 pages, 20 figures; accepted for publication in ApJ Supplement
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