State University of Santa Cruz

About: State University of Santa Cruz is a education organization based out in Ilhéus, Brazil. It is known for research contribution in the topics: Population & Species richness. The organization has 3266 authors who have published 4642 publications receiving 51876 citations. The organization is also known as: Universidade Estadual de Santa Cruz.

Diagnostic tool to analyse colour–magnitude diagrams of poorly populated stellar concentrations

Abstract: The dynamical processes that lead to open cluster disruption cause its mass to decrease. To investigate such processes from the observational point of view, it is important to identify open cluster remnants (OCRs), which are intrinsically poorly populated. Due to their nature, distinguishing them from field star fluctuations is still an unresolved issue. In this work, we developed a statistical diagnostic tool to distinguish poorly populated star concentrations from background field fluctuations. We use 2MASS photometry to explore one of the conditions required for a stellar group to be a physical group: to produce distinct sequences in a colour-magnitude diagram (CMD). We use automated tools to (i) derive the limiting radius; (ii) decontaminate the field and assign membership probabilities; (iii) fit isochrones; and (iv) compare object and field CMDs, considering the isochrone solution, in order to verify the similarity. If the object cannot be statistically considered as a field fluctuation, we derive its probable age, distance modulus, reddening and uncertainties in a self-consistent way. As a test, we apply the tool to open clusters and comparison fields. Finally, we study the OCR candidates DoDz 6, NGC 272, ESO 435 SC48 and ESO 325 SC 15. The tool is optimized to treat these low-statistic objects and to separate the best OCR candidates for studies on kinematics and chemical composition. The study of the possible OCRs will certainly provide a deep understanding of OCR properties and constraints for theoretical models, including insights into the evolution of open clusters and dissolution rates.

Alternative reproductive modes of Atlantic forest frogs

Abstract: Diversity in reproductive modes is well known in amphibians, mainly among anurans, which are characterized by a diversity in breeding biology that exceeds that of any other tetrapod. Currently, 39 reproductive modes are recognized among anurans and some species display more than one mode. The breeding biology of some Brazilian Atlantic forest anurans was investigated for this study. We observed unreported reproductive modes for six species, variability in the reproductive modes of individuals of the same species (whereby some individuals of a given population displayed unusual reproductive modes when the physical conditions of the breeding site were suboptimal), and variations within the modes. These observations suggest possible evolutionary steps for the reproductive modes. Anuran breeding biology seems to be more diverse than previously reported, and a character matrix could be constructed to describe the total range of variation of the anuran reproductive modes.

Investigating the rotational evolution of young, low-mass stars using Monte Carlo simulations

Abstract: Context. Young stars rotate well below break-up velocity, which is thought to result from the magnetic coupling with their accretion disk.Aims. We investigate the rotational evolution of young stars under the disk-locking hypothesis through Monte Carlo simulations.Methods. Our simulations included 280 000 stars, each of which was initially assigned a mass, a rotational period, and a mass accretion rate. The mass accretion rate depends on both mass and time, following power-law indices of 1.4 and −1.5, respectively. A mass-dependent accretion threshold was defined below which a star was considered as diskless, which resulted in a distribution of disk lifetimes that matches observations. Stars were evolved at constant angular spin rate while accreting and at constant angular momentum when they became diskless.Results. Starting with a bimodal distribution of periods for disk and diskless stars, we recovered the bimodal period distribution seen in several young clusters. The short-period peak mostly consists of diskless stars, and the long-period peak is mainly populated by accreting stars. Both distributions, however, present a long tail toward long periods, and a population of slowly rotating diskless stars is observed at all ages. We reproduced the observed correlations between disk fraction and spin rate, as well as between IR excess and rotational period. The period-mass relation we derived from the simulations only shows the same global trend as observed in young clusters when we released the disk-locking assumption for the lowest mass stars. Finally, we find that the time evolution of median specific angular momentum follows a power-law index of −0.65 for accreting stars, as expected from disk locking, and of −0.53 for diskless stars, a shallower slope that results from a wide distribution of disk lifetimes. At the end of the accretion phase, our simulations reproduce the angular momentum distribution of the low-mass members of the 13 Myr h Per cluster.Conclusions. Using observationally documented distributions of disk lifetimes, mass accretion rates, and initial rotation periods, and evolving an initial population from 1 to 12 Myr, we reproduced the main characteristics of pre-main sequence angular momentum evolution, which supports the disk-locking hypothesis.

Domestic Dog Invasion in an Agroforestry Mosaic in Southern Bahia, Brazil

Abstract: Although the value of agroforests for biodiversity conservation has been frequently highlighted, little is known about the susceptibility of this production system to biological invasions. Drawing ...

Use of Multivariate Analysis Techniques for Evaluation of Analytical Data—Determination of the Mineral Composition of Cabbage (Brassica oleracea)

Abstract: Cabbage (Brassica oleracea) is a vegetable food that is found in red and white varieties, and it has been consumed worldwide as raw or cooked In this paper, the mineral composition of cabbage collected in 24 Brazilian cities was determined and the results were evaluated using multivariate analysis The samples were digested using nitric acid and hydrogen peroxide and were analyzed using inductively coupled plasma optical emission spectrometry The accuracy of the method was confirmed by analysis of a certified reference material of spinach leaves, furnished by National Institute of Standard and Technology The study involved 55 samples, being 31 of the white specie and 24 of the red specie The results expressed as milligrams of element per kilogram of sample demonstrated that the concentration ranges varied from 1,6029 to 4,0683 for potassium, 2175 to 7662 for phosphorous, 2219 to 7447 for calcium, 672 to 2860 for magnesium, 081 to 440 for manganese, 191 to 860 for iron, 001 to 024 for molybdenum, 117 to 510 for zinc, 272 to 5910 for sodium, and 035 to 579 for strontium The principal component analysis and hierarchical cluster analysis evidenced that the mineral composition of the red specie is not different of the white specie