1,566 research outputs found
Factors influencing wild chimpanzee (Pan troglodytes verus) relative abundance in an agriculture-swamp matrix outside protected areas
This study was funded by a grant from the Arcus Foundation No. G-PGM-1508-1368 to TH; PA was supported by the MINECO and the Universidad de Castilla-La Mancha (UCLM) through a 'Ramón y Cajal' contract (RYC-2012-11970), and Tacugama Chimpanzee Sanctuary provided logistical support. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We are grateful to the Ministry of Agriculture, Forestry and Food Security of the Sierra Leone Government for granting us permission to conduct this research. This work would not have been possible without the collaboration of the people in the study communities. We also thank the outreach and management teams at the Tacugama Chimpanzee Sanctuary, in particular David Momoh, Joseph Marah, Konkofa Marah, Yirah Koroma, Bockarie Kanneh and Natalia Casado, for their assistance in the field. We are also extremely grateful to Dr. Raj Amin, Institute of Zoology in London, for providing the camera trap analysis software and to Jasper Gilardi for his help with processing camera trap images. Finally, we would also like to thank the two anonymous reviewers who provided useful suggestions for improving the quality of this manuscript.Human population growth and anthropogenic activities are exacerbating pressures on biodiversity globally. Land conversion is aggravating habitat fragmentation and non-human primates are increasingly compelled to live in forest-agricultural mosaics. In Sierra Leone, more than half of the wild chimpanzee population (Pan troglodytes verus) occurs outside protected areas and competes for resources with farmers. Our study area, in the Moyamba district in south-western Sierra Leone, is practically devoid of forest and is dominated by cultivated and fallow fields, swamps and mangroves. In this region, traditional slash-and-burn agriculture modifies annually the landscape, sparing swamps and mangroves and semi-domesticated oil palms (Elaeis guineensis). This study aimed to explore ecological and anthropogenic factors influencing chimpanzee relative abundance across this highly degraded and human-impacted landscape. Between 2015 and 2016, we deployed 24 camera traps systematically across 27 1.25x1.25 km grid cells. Cameras were operational over a period of 8 months. We used binomial iCAR models to examine to what extent anthropogenic (roads, settlements, abandoned settlements and human presence) and habitat variables (swamps, farmland and mangroves) shape chimpanzee relative abundance. The best model explained 43.16% of the variation with distance to roads and swamps emerging as the best predictors of chimpanzee relative abundance. Our results suggest that chimpanzees avoid roads and prefer to maintain proximity to swamps. There was no significant effect of settlements, abandoned settlements, mangroves or human presence. It appears that chimpanzees do not avoid areas frequented by people; although, our findings suggest temporal avoidance between the two species. We highlight the importance of studying chimpanzee populations living in anthropogenic habitats like agricultural-swamp matrixes to better understand factors influencing their distribution and inform conservation planning outside protected areas
Metodologías e indicadores académicos, económicos, sociales y tecnológicos para la evaluación del impacto de la investigación científica universitaria
Given the importance of the research component to provide pertinent answers to economic and social problems and demands, decision-making in terms of scientific policy, resource management and infrastructure development in university institutions, it is necessary to evaluate the impact of scientific investigations carried out. Research is a strategy of searching for knowledge, as well as a source of innovation and constant learning of reality, becoming a key factor for technological and educational transformation. The purpose of this review article is to perform an analysis of the different methodologies and indicators academic, economic, social and technological that have been implemented to evaluate the impact of university research.Given the importance of the research component to provide pertinent answers to economic and social problems and demands, decision-making in terms of scientific policy, resource management and infrastructure development in university institutions, it is necessary to evaluate the impact of scientific investigations carried out. Research is a strategy of searching for knowledge, as well as a source of innovation and constant learning of reality, becoming a key factor for technological and educational transformation. The purpose of this review article is to perform an analysis of the different methodologies and indicators academic, economic, social and technological that have been implemented to evaluate the impact of university research.Dada la importancia del componente investigación para dar respuestas pertinentes a los problemas y demandas económicas y sociales, toma de decisiones en términos de política científica, gestión de recursos y desarrollo de infraestructura en las instituciones universitarias se hace necesario evaluar el impacto de las investigaciones científicas ejecutadas. La investigación es una estrategia de búsqueda del conocimiento, así como fuente de innovación y aprendizaje constante de la realidad, constituyéndose en un factor clave para la transformación tecnológica y educativa. El propósito de este artículo de revisión es realizar un análisis de las diferentes metodologías e indicadores académicos, económicos, sociales y tecnológicos que se han implementado para evaluar el impacto de las investigaciones universitarias
Dielectric susceptibility of the Coulomb-glass
We derive a microscopic expression for the dielectric susceptibility
of a Coulomb glass, which corresponds to the definition used in classical
electrodynamics, the derivative of the polarization with respect to the
electric field. The fluctuation-dissipation theorem tells us that is a
function of the thermal fluctuations of the dipole moment of the system. We
calculate numerically for three-dimensional Coulomb glasses as a
function of temperature and frequency
High spatial resolution optical imaging of the multiple T Tauri system LkH{\alpha} 262/LkH{\alpha} 263
We report high spatial resolution i' band imaging of the multiple T Tauri
system LkH 262/LkH 263 obtained during the first commissioning
period of the Adaptive Optics Lucky Imager (AOLI) at the 4.2 m William Herschel
Telescope, using its Lucky Imaging mode. AOLI images have provided photometry
for each of the two components LkH 263 A and B (0.41 arcsec separation)
and marginal evidence for an unresolved binary or a disc in LkH 262.
The AOLI data combined with previously available and newly obtained optical and
infrared imaging show that the three components of LkH 263 are
co-moving, that there is orbital motion in the AB pair, and, remarkably, that
LkH 262-263 is a common proper motion system with less than 1 mas/yr
relative motion. We argue that this is a likely five-component gravitationally
bounded system. According to BT-settl models the mass of each of the five
components is close to 0.4 M and the age is in the range 1-2 Myr. The
presence of discs in some of the components offers an interesting opportunity
to investigate the formation and evolution of discs in the early stages of
multiple very low-mass systems. In particular, we provide tentative evidence
that the disc in 263C could be coplanar with the orbit of 263AB.Comment: 11 pages, 7 figures, Accepted 2016 May
The O3N2 and N2 abundance indicators revisited: improved calibrations based on CALIFA and Te-based literature data
The use of IFS is since recently allowing to measure the emission line fluxes
of an increasingly large number of star-forming galaxies both locally and at
high redshift. The main goal of this study is to review the most widely used
empirical oxygen calibrations, O3N2 and N2, by using new direct abundance
measurements. We pay special attention to the expected uncertainty of these
calibrations as a function of the index value or abundance derived and the
presence of possible systematic offsets. This is possible thanks to the
analysis of the most ambitious compilation of Te-based HII regions to date.
This new dataset compiles the Te-based abundances of 603 HII regions extracted
from the literature but also includes new measurements from the CALIFA survey.
Besides providing new and improved empirical calibrations for the gas
abundance, we also present here a comparison between our revisited calibrations
with a total of 3423 additional CALIFA HII complexes with abundances derived
using the ONS calibration by Pilyugin et al. (2010). The combined analysis of
Te-based and ONS abundances allows us to derive their most accurate calibration
to date for both the O3N2 and N2 single-ratio indicators, in terms of all
statistical significance, quality and coverage of the space of parameters. In
particular, we infer that these indicators show shallower abundance
dependencies and statistically-significant offsets compared to those of Pettini
and Pagel (2004), Nagao et al. (2006) and P\'erez-Montero and Contini (2009).
The O3N2 and N2 indicators can be empirically applied to derive oxygen
abundances calibrations from either direct abundance determinations with random
errors of 0.18 and 0.16, respectively, or from indirect ones (but based on a
large amount of data) reaching an average precision of 0.08 and 0.09 dex
(random) and 0.02 and 0.08 dex (systematic; compared to the direct
estimations),respectively.Comment: 12 pages, 5 figures, accepted for publication in A&
PINGS: the PPAK IFS Nearby Galaxies Survey
We present the PPAK Integral Field Spectroscopy (IFS) Nearby Galaxies Survey:
PINGS, a 2-dimensional spectroscopic mosaicking of 17 nearby disk galaxies in
the optical wavelength range. This project represents the first attempt to
obtain continuous coverage spectra of the whole surface of a galaxy in the
nearby universe. The final data set comprises more than 50000 individual
spectra, covering in total an observed area of nearly 80 arcmin^2. In this
paper we describe the main astrophysical issues to be addressed by the PINGS
project, we present the galaxy sample and explain the observing strategy, the
data reduction process and all uncertainties involved. Additionally, we give
some scientific highlights extracted from the first analysis of the PINGS
sample.Comment: Accepted for publication in MNRAS, 26 pages, 14 figures (some in low
resolution), 3 table
SDSS-IV MANGA: Spatially Resolved Star Formation Main Sequence and LI(N)ER Sequence
We present our study on the spatially resolved H_alpha and M_star relation
for 536 star-forming and 424 quiescent galaxies taken from the MaNGA survey. We
show that the star formation rate surface density (Sigma_SFR), derived based on
the H_alpha emissions, is strongly correlated with the M_star surface density
(Sigma_star) on kpc scales for star- forming galaxies and can be directly
connected to the global star-forming sequence. This suggests that the global
main sequence may be a consequence of a more fundamental relation on small
scales. On the other hand, our result suggests that about 20% of quiescent
galaxies in our sample still have star formation activities in the outer region
with lower SSFR than typical star-forming galaxies. Meanwhile, we also find a
tight correlation between Sigma_H_alpha and Sigma_star for LI(N)ER regions,
named the resolved "LI(N)ER" sequence, in quiescent galaxies, which is
consistent with the scenario that LI(N)ER emissions are primarily powered by
the hot, evolved stars as suggested in the literature.Comment: 6 pages, 4 figures. ApJ Letter accepte
Integral field spectroscopy of nitrogen overabundant blue compact dwarf galaxies
We study the spatial distribution of the physical properties and of oxygen
and nitrogen abundances in three Blue Compact Dwarf Galaxiess (HS 0128+2832, HS
0837+4717 and Mrk 930) with a reported excess of N/O in order to investigate
the nature of this excess and, particularly, if it is associated with
Wolf-Rayet (WR) stars We have observed these BCDs by using PMAS integral field
spectroscopy in the optical spectral range (3700 - 6900 {\AA}), mapping their
physical-chemical properties, using both the direct method and appropriate
strong-line methods. We make a statistical analysis of the resulting
distributions and we compare them with the integrated properties of the
galaxies. Our results indicate that outer parts of the three galaxies are
placed on the "AGN-zone" of the [NII]/H{\alpha} vs. [OIII]/H{\beta} diagnostic
diagram most likely due to a high N/O combined with the excitation structure in
these regions. From the statistical analysis, it is assumed that a certain
property can be considered as spatially homogeneous (or uniform) if a normal
gaussian function fits its distribution in several regions of the galaxy.
Moreover, a disagreement between the integrated properties and the mean values
of the distribution usually appears when a gaussian does not fit the
corresponding distribution. We find that for Mrk 930, the uniformity is found
for all parameters, except for electron density and reddening. The rotation
curve together with the H{\alpha} map and UV images, reveal a perturbed
morphology and possible interacting processes. The N/O is found to be constant
in the three studied objects at spatial scales of the order of several kpc so
we conclude that the number of WR stars estimated from spectroscopy is not
sufficient to pollute the ISM and to produce the observed N/O excess in these
objectsComment: 17 pages, 14 figures, accepted for publication in Astronomy &
Astrophysic
Changes in soil water repellency increased preferential flow and soil erosion risk after intense wildfire (Huelva, 2004)
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