710 research outputs found
The release of a captive-raised female African Elephant <em>(Loxodonta africana</em>) in the Okavango Delta, Botswana
Wild female elephants live in close-knit matrilineal groups and housing captive elephants in artificial social groupings can cause significant welfare issues for individuals not accepted by other group members. We document the release of a captive-raised female elephant used in the safari industry because of welfare and management problems. She was fitted with a satellite collar, and spatial and behavioural data were collected over a 17-month period to quantify her interactions with the wild population. She was then monitored infrequently for a further five-and-a-half years. We observed few signs of aggression towards her from the wild elephants with which she socialized. She used an area of comparable size to wild female elephants, and this continued to increase as she explored new areas. Although she did not fully integrate into a wild herd, she had three calves of her own, and formed a social unit with another female and her calf that were later released from the same captive herd. We recommend that release to the wild be considered as a management option for other captive female elephants
An Analysis of Masked Bobwhite Collection Locales and Habitat Characteristics
We evaluated the collecting locales of 251 masked bobwhite (Colinus virginianus ridgwayi) specimens in museum collections. Eighteen were from 4 sites in Arizonaâall collected by Herbert Brown. The vast majority (93%) of specimens were from the Mexican State of Sonora. We visited and photographed each of the Arizona collection locations and most of the sites in Sonora. Collector descriptions indicate the birdâs principal habitat affiliations were with tall grass-weed (1â4 forb) pastures, savannas, and farm fields. All historic localities visited were either in grass-forb habitats along drainages or in present or former savannas adjacent to woody cover and/or agricultural fields between 240 and 1,060 m elevation. These sites were remarkably similar to other bobwhite habitats in subtropic-tropic South Texas and Oaxaca, Mexico. Masked bobwhite habitat was a diverse tropic-subtropic grassland within or adjacent to dense woody cover (thornscrub) and/or farmland. These habitats experienced alterations and loss of the tall grass-weed component due to livestock husbandry. Some former habitat sites appear to have recovered, however, and restoration of the subspecies might be possible if suitable stock exists. Unfortunately, this bird may now be functionally extinct
Brane decay of a (4+n)-dimensional rotating black hole: spin-0 particles
In this work, we study the `scalar channel' of the emission of Hawking
radiation from a (4+n)-dimensional, rotating black hole on the brane. We
numerically solve both the radial and angular part of the equation of motion
for the scalar field, and determine the exact values of the absorption
probability and of the spheroidal harmonics, respectively. With these, we
calculate the particle, energy and angular momentum emission rates, as well as
the angular variation in the flux and power spectra -- a distinctive feature of
emission during the spin-down phase of the life of the produced black hole. Our
analysis is free from any approximations, with our results being valid for
arbitrarily large values of the energy of the emitted particle, angular
momentum of the black hole and dimensionality of spacetime. We finally compute
the total emissivities for the number of particles, energy and angular momentum
and compare their relative behaviour for different values of the parameters of
the theory.Comment: 24 pages, 13 figure
The social and ecological integration of captive-raised adolescent male African elephants (Loxodonta africana) into a wild population
BACKGROUND: A rapid rise in the number of captive African elephants (Loxodonta africana) used in the tourism industry in southern Africa and orphaned elephants in human care has led to concerns about their long-term management, particularly males. One solution is to release them into the wild at adolescence, when young males naturally leave their herd. However, this raises significant welfare concerns: little is known about how well released elephants integrate into wild populations and whether they pose a greater threat to humans than wild elephants. We document the release of three captive-raised adolescent male African elephants in the Okavango Delta, Botswana. METHODOLOGY/PRINCIPAL FINDINGS: Despite having been part of a herd of working elephants for at least eight years, the three males progressively integrated into the complex fission-fusion society of wild bull elephants. In the three years following release, they showed no tendency to be closer to human habitation, and there were no significant differences between wild and captive-raised adolescent males in the total number of social interactions, size of ranges and habitat use. However, the captive-raised elephants sparred less and vocalised more, and spent more time alone and in smaller social groups. Thereafter the released elephants continued to expand their ranges and interact with both mixed-sex herds and males. One male was shot by farmers 94 months after release, along with ten wild elephants, on a ranch outside the protected area. CONCLUSIONS/SIGNIFICANCE: We show that captive-raised adolescent male elephants can integrate into a wild population. Long-term studies are required to determine the longevity, breeding success, and eventual fate of released male elephants, but we identified no significant short-term welfare problems for the released elephants or recipient population. Release of captive-raised mammals with complex social systems is a husbandry option that should be explored further
Gemini/GMOS Imaging of Globular Cluster Systems in Five Early-type Galaxies
This paper presents deep high quality photometry of globular cluster (GC)
systems belonging to five early-type galaxies covering a range of mass and
environment. Photometric data were obtained with the Gemini North and Gemini
South telescopes in the filter passbands g', r', and i'. The combination of
these filters with good seeing conditions allows an excellent separation
between GC candidates and unresolved field objects. Bimodal GC colour
distributions are found in all five galaxies. Most of the GC systems appear
bimodal even in the (g' -r') vs (r' -i') plane. A population of
resolved/marginally resolved GC and Ultra Compact Dwarf candidates was found in
all the galaxies. A search for the so-called "blue tilt" in the
colour-magnitude diagrams reveals that NGC 4649 clearly shows that phenomenon
although no conclusive evidence was found for the other galaxies in the sample.
This "blue tilt" translates into a mass-metallicity relation given by Z \propto
M^0.28\pm0.03 . This dependence was found using a new empirical (g' -i') vs
[Z/H] relation which relies on an homogeneous sample of GC colours and
metallicities. This paper also explores the radial trends in both colour and
surface density for the blue (metal-poor) and red (metal-rich) GC
subpopulations. As usual, the red GCs show a steeper radial distribution than
the blue ones. Evidence of galactocentric colour gradients is found in some of
the GC systems, being more significant for the two S0 galaxies in the sample.
Red GC subpopulations show similar colours and gradients to the galaxy halo
stars in their inner region. A GC mean colour-galaxy luminosity relation,
consistent with [Z/H] \propto L_B ^0.26\pm0.08, is present for the red GCs. An
estimate of the total GC populations and specific frequency SN values is
presented for NGC 3115, NGC 3379, NGC 3923 and NGC 4649.Comment: 23 pages, 13 figures and 9 tables. Tables A1 and A2 will be published
in full online only. Accepted for publication in MNRA
Distributions of charged massive scalars and fermions from evaporating higher-dimensional black holes
A detailed numerical analysis is performed to obtain the Hawking spectrum for
charged, massive brane scalars and fermions on the approximate background of a
brane charged rotating higher-dimensional black hole constructed in
arXiv:0907.5107. We formulate the problem in terms of a "spinor-like" first
order system of differential wave equations not only for fermions, but for
scalars as well and integrate it numerically. Flux spectra are presented for
non-zero mass, charge and rotation, confirming and extending previous results
based on analytic approximations. In particular we describe an inverted charge
splitting at low energies, which is not present in four or five dimensions and
increases with the number of extra dimensions. This provides another signature
of the evaporation of higher-dimensional black holes in TeV scale gravity
scenarios.Comment: 19 pages, 6 figures, minor typos corrected, 1 page added with a
discussion on higher spins, added reference
Influence of a Brane Tension on Phantom and Massive Scalar Field Emission
We elaborate the signature of the extra dimensions and brane tension in the
process of phantom and massive scalar emission in the spacetime of
(4+n)-dimensional tense brane black hole. Absorption cross section, luminosity
of Hawking radiation and cross section in the low-energy approximation were
found. We envisage that parameter connected with the existence of a brane
imprints its role in the Hawking radiation of the considered fields.Comment: 7 pages, * figures, RevTex, to be published in General Relativity and
Gravitatio
Noncommutative geometry inspired black holes in higher dimensions at the LHC
When embedding models of noncommutative geometry inspired black holes into
the peridium of large extra dimensions, it is natural to relate the
noncommutativity scale to the higher-dimensional Planck scale. If the Planck
scale is of the order of a TeV, noncommutative geometry inspired black holes
could become accessible to experiments. In this paper, we present a detailed
phenomenological study of the production and decay of these black holes at the
Large Hadron Collider (LHC). Noncommutative inspired black holes are relatively
cold and can be well described by the microcanonical ensemble during their
entire decay. One of the main consequences of the model is the existence of a
black hole remnant. The mass of the black hole remnant increases with
decreasing mass scale associated with noncommutative and decreasing number of
dimensions. The experimental signatures could be quite different from previous
studies of black holes and remnants at the LHC since the mass of the remnant
could be well above the Planck scale. Although the black hole remnant can be
very heavy, and perhaps even charged, it could result in very little activity
in the central detectors of the LHC experiments, when compared to the usual
anticipated black hole signatures. If this type of noncommutative inspired
black hole can be produced and detected, it would result in an additional mass
threshold above the Planck scale at which new physics occurs.Comment: 21 pages, 7 figure
- âŠ