972 research outputs found
Factors affecting the home range size of felids (Mammalia, Carnivora) with emphasis on three American species
El objetivo de este estudio fue evaluar los factores que influyen en el tamaño del ámbito hogareño de felinos en los niveles inter- e intraespecífico. En nivel interespecífico, evaluamos la influencia de la masa corporal en el ámbito hogareño de 19 especies de felinos, controlando la filogenia. A nivel de especies, evaluamos el efecto del sexo y el hábitat (abierto vs. cerrado) sobre el ámbito hogareño de tres especies de felinos americanos, Panthera onca, Leopardus pardalis y Puma concolor, para los cuales existe una buena cantidad de información. Los datos de masa corporal, sexo y ámbito hogareño fueron extraídos de la base de datos Pantheria (para 19 especies, para comparación interespecífica) y 48 estudios para la variación intraespecífica. Evaluamos la influencia de la masa corporal en el tamaño del ámbito hogareño de felinos utilizando un análisis filogenético de los mínimos cuadrados generalizados. Evaluamos la existencia de dimorfismo sexual en el ámbito hogareño y la masa corporal usando una prueba t pareada. Finalmente, investigamos la influencia del hábitat en el ámbito hogareño utilizando un modelo ANOVA. Nuestros resultados mostraron que el tamaño del ámbito hogareño está asociado positivamente con la masa corporal en felinos. A nivel intraespecífico, confirmamos que la masa corporal y el ámbito hogareño de los machos son mayores que los de las hembras en P. onca y L. pardalis y P. concolor. Además, el ámbito hogareño de P. onca aumenta en hábitats abiertos (i.e., pastizales, desiertos y matorrales), tal como se esperaba. En general, nuestros resultados confirman que los mayores ámbitos hogareños están asociados con un tamaño corporal más grande en los animales que necesitan más recursos alimentarios o recursos específicos (como presas para felinos) para satisfacer las tasas metabólicas. Además, el ámbito hogareño de los tres felinos parece estar muy influenciado por los atributos de reproducción, así como por la calidad del hábitat. Esto sugiere una conexión con la distribución espacial de alimentos (presas) y las oportunidades de apareamiento.We evaluated several factors that might be related to the home-range size of felids at both inter and intraspecific levels. At the interspecific level, we tested the influence of body mass on home range size of 19 felid species, while controlling for phylogeny. At the species level, we evaluated the effect of sex and habitat type (open vs. closed) on the home range size of three species of felids occurring in America, Panthera onca, Leopardus pardalis and Puma concolor, which are among the most studied species concerning home ranges. Body mass, sex, and home range data were extracted from the Pantheria database (for 19 species, for interspecific comparisons) and from 48 studies for intraspecific comparisons. We assessed the influence of body mass on the home range size of felids using phylogenetic generalized least squares analysis. We evaluated the existence of sexual dimorphism on both home range size and body mass using paired t-tests. Finally, we investigated the influence of habitat type (open vs. closed) on home range size using ANOVA. Our results show that home range size is positively influenced by body mass in felids. At the intraspecific level, we confirmed that both the body mass and home range are larger for males than for the females in P. onca, L. pardalis and P. concolor. Moreover, the average home range size of P. onca is larger in open (i.e., grasslands, deserts and shrublands) than in closed (i.e., forests) habitats. Overall, our results confirm that larger home ranges are associated with larger body sizes in animals that need a large amount of food resources or specific resources (such as the specific prey requirements of felids) to maintain their metabolic rates. Furthermore, home range size of these three felids seems to be strongly influenced by reproductive attributes as well as by habitat quality, suggesting a connection with the spatial distribution of both food (prey) and mates
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Spanish validation of the revised depression attitude questionnaire (R-daq)
Purpose: The aim of the study was to develop and validate a Spanish version of the Revised Depression Attitude Questionnaire (R-DAQ). Methods: The R-DAQ was used as a baseline for the study. It was translated and tested to ensure the instrument was appropriate for the target population. 537 Ecuadorian healthcare professionals completed the revised Spanish version of the R-DAQ (SR-DAQ). Statistical and exploratory factor analyses were performed to examine construct validity, internal consistency, readability and floor and ceiling effects. Results: Three factors were obtained: “Professional confidence in depression care”; “Therapeutic optimism about depression”; and “Generalist perspective about depression occurrence, recognition, and management”. The internal consistency of the SR-DAQ was determined by means of Cronbach’s α coefficient, with values ranging between 0.61–0.8. The correlations with the English version reflected adequate validity. The model explained 39% of the variance. Subsequent analysis with a sample restricted to those who had received training in depression produced a model that explained 42% of the variance. Conclusion: The SR-DAQ meets the psychometric requirements for measuring depression attitude in a Spanish-speaking population and shows adequate internal consistency and validity
Understanding stellar activity-induced radial velocity jitter using simultaneous K2 photometry and HARPS RV measurements
One of the best ways to improve our understanding of the stellar
activity-induced signal in radial velocity (RV) measurements is through
simultaneous high-precision photometric and RV observations. This is of prime
importance to mitigate the RV signal induced by stellar activity and therefore
unveil the presence of low-mass exoplanets. The K2 Campaign 7 and 8
field-of-views were located in the southern hemisphere, and provided a unique
opportunity to gather unprecedented simultaneous high precision photometric
observation with K2 and high-precision RV measurements with the HARPS
spectrograph to study the relationship between photometric variability and RV
jitter. We observed nine stars with different levels of activity; from quiet to
very active. We probe the presence of any meaningful relation between measured
RV jitter and the simultaneous photometric variation, and also other activity
indicators (e.g. BIS, FWHM, , and F8), by evaluating the strength
and significance of the correlation between RVs and each indicator. We found
that for the case of very active stars, strong and significant correlations
exist between almost all the observables and measured RVs; however, for lower
activity levels the correlations become random. Except for the F8 which its
strong correlation with RV jitter persists over a wide range of stellar
activity level, and thus our result suggests that F8 might be a powerful proxy
for activity induced RV jitter. Moreover, we examine the capability of two
state-of-the-art modeling techniques, namely the FF' method and SOAP2.0, in
accurately predicting the RV jitter amplitude using the simultaneous
photometric observation. We found that for the very active stars both
techniques can reasonably well predict the amplitude of the RV jitter, however,
at lower activity levels the FF' method underpredicts the RV jitter amplitude.Comment: 13 pages, 7 figures, 2 tables, accepted for publication in A&
Perturbation theory of PT-symmetric Hamiltonians
In the framework of perturbation theory the reality of the perturbed
eigenvalues of a class of \PTsymmetric Hamiltonians is proved using stability
techniques. We apply this method to \PTsymmetric unperturbed Hamiltonians
perturbed by \PTsymmetric additional interactions
The CORALIE survey for southern extrasolar planets. XVI. Discovery of a planetary system around HD 147018 and of two long period and massive planets orbiting HD 171238 and HD 204313
We report the detection of a double planetary system around HD 140718 as well
as the discovery of two long period and massive planets orbiting HD 171238 and
HD 204313. Those discoveries were made with the CORALIE Echelle spectrograph
mounted on the 1.2-m Euler Swiss telescope located at La Silla Observatory,
Chile. The planetary system orbiting the nearby G9 dwarf HD 147018 is composed
of an eccentric inner planet (e=0.47) with twice the mass of Jupiter (2.1 MJup
) and with an orbital period of 44.24 days. The outer planet is even more
massive (6.6 MJup) with a slightly eccentric orbit (e=0.13) and a period of
1008 days. The planet orbiting HD 171238 has a minimum mass of 2.6 MJup, a
period of 1523 days and an eccentricity of 0.40. It orbits a G8 dwarfs at 2.5
AU. The last planet, HD 204313 b, is a 4.0 MJup -planet with a period of 5.3
years and has a low eccentricity (e = 0.13). It orbits a G5 dwarfs at 3.1 AU.
The three parent stars are metal rich, which further strengthened the case that
massive planets tend to form around metal rich stars.Comment: 6 pages, 6 figures, accepted for publication in A&
A note on the differences of computably enumerable reals
We show that given any non-computable left-c.e. real α there exists a left-c.e. real β such that α≠β+γ for all left-c.e. reals and all right-c.e. reals γ. The proof is non-uniform, the dichotomy being whether the given real α is Martin-Loef random or not. It follows that given any universal machine U, there is another universal machine V such that the halting probability of U is not a translation of the halting probability of V by a left-c.e. real. We do not know if there is a uniform proof of this fact
One and two-center processes in high-order harmonic generation in diatomic molecules: influence of the internuclear separation
We analyze the influence of different recombination scenarios, involving one
or two centers, on high-order harmonic generation (HHG) in diatomic molecules,
for different values of the internuclear separation. We work within the
strong-field approximation, and employ modified saddle-point equations, in
which the structure of the molecule is incorporated. We find that the
two-center interference patterns, attributed to high-order harmonic emission at
spatially separated centers, are formed by the quantum interference of the
orbits starting at a center and finishing at a different center in the molecule with those starting and ending at a same center
Within our framework, we also show that contributions starting at different
centers exhibit different orders of magnitude, due to the influence of
additional potential-energy shifts. This holds even for small internuclear
distances. Similar results can also be obtained by considering single-atom
saddle-point equations and an adequate choice of molecular prefactors.Comment: 8 pages, 5 figure
Fetal Hemodynamic Parameters in Low Risk Pregnancies: Doppler Velocimetry of Uterine, Umbilical, and Middle Cerebral Artery
Objective. To elaborate curves of longitudinal reference intervals of pulsatility index (PI) and systolic velocity (SV) for uterine (UtA), umbilical (UA), and middle cerebral arteries (MCA), in low risk pregnancies. Methods. Doppler velocimetric measurements of PI and SV from 63 low risk pregnant women between 16 and 41 weeks of gestational age. Means (±SD) for intervals of gestational age and percentiles 5, 50, and 95 were calculated for each parameter. The Intraclass Correlation Coefficients (ICC) were also estimated for assessing intra- and intervariability of measurements. Results. Mean PI of UtA showed decreasing values during pregnancy, but no regular pattern was identified for mean SV. For UA, PI decreased and SV increased along gestation. MCA presented PI increasing values until 32–35 weeks. SV showed higher levels with increasing gestation. High ICC values indicated good reproducibility. Conclusions. Reference intervals for the assessment of SV and PI of UtA, UA, and MCA were established. These reference intervals showed how a normal pregnancy is expected to progress regarding these Doppler velocimetric parameters and are useful to follow high risk pregnancies. The comparison between results using different curves may provide insights about the best patterns to be used
Search for radial velocity variations in eight M-dwarfs with NIRSPEC/Keck II
Context. Radial velocity (RV) measurements from near-infrared spectra have
become a potentially powerful tool to search for planets around cool stars and
sub-stellar objects. As part of a large survey to characterize M-dwarfs using
NIRSPEC at Keck II, we obtained spectra of eight late M-dwarfs (spectral types
M5.0-M8.0) during two or more observing epochs per target. These spectra were
taken with intermediate spectral resolving powers (R \sim 20,000) in the
J-band.
Aims. We search for relative radial velocity variability in these late
M-dwarfs and test the NIRSPEC capability of detecting short period brown dwarf
and massive planetary companions around low-mass stars in the J-band (\approx
1.25 micron). Additionally, we reanalyzed the data of the M8-type star vB10
(one of our targets) presented in Zapatero Osorio et al. (2009), which were
obtained with the same instrumentation as our data.
Methods. [...]
Results. For the entire M-dwarf sample, we do not find any evidence of
relative RV variations induced by a short period brown dwarf or massive
planetary companion. The typical RV precision of the measurements is between
180 and 300 m/s, which is sufficient to detect hot Neptunes around M-dwarfs.
Also, we find that the spurious RV shift in Zapatero et al. (2009) of the star
VB10 was caused by asymmetries in the instrumental profile between different
observing epochs, which were not taken into account in their analysis.Comment: A&A, 7 pages, 5 figure
On the Atomic Photoeffect in Non-relativistic QED
In this paper we present a mathematical analysis of the photoelectric effect
for one-electron atoms in the framework of non-relativistic QED. We treat
photo-ionization as a scattering process where in the remote past an atom in
its ground state is targeted by one or several photons, while in the distant
future the atom is ionized and the electron escapes to spacial infinity. Our
main result shows that the ionization probability, to leading order in the
fine-structure constant, , is correctly given by formal time-dependent
perturbation theory, and, moreover, that the dipole approximation produces an
error of only sub-leading order in . In this sense, the dipole
approximation is rigorously justified.Comment: 25 page
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