4,210 research outputs found
The genus Bolbelasmus in the western and southern regions of the Mediterranean Basin (Coleoptera: Geotrupidae: Bolboceratinae)
The Bolbelasmus Boucomont, 1911 species of the western and southern
regions of the Mediterranean Basin (Northern Africa, Iberian Peninsula and
France) are revised. The following three new species are described: Bolbelasmus
brancoi Hillert & Král sp. nov. and Bolbelasmus howdeni Hillert & Král sp. nov.,
both from Spain and Gibraltar, and Bolbelasmus nikolajevi Hillert, Arnone, Král &
Massa sp. nov. from Egypt, Libya and Tunisia. Bolbelasmus vaulogeri (Abeille de
Perrin, 1898) stat. restit. is removed from synonymy with B. bocchus (Erichson,
1841) and reinstated as a separate species. Bolbelasmus romanorum Arnone &
Massa, 2010 is considered a junior subjective synonym of B. vaulogeri. Lectotypes
for Bolboceras bocchus Erichson, 1841 and Bolboceras vaulogeri Abeille
de Perrin, 1898 are designated. Relevant diagnostic characters (head, pronotum,
elytron, external male genitalia) are illustrated. Identifi cation keys for both males
and females, and an annotated list of the Western Palaearctic representatives of the
genus Bolbelasmus are presented. Finally, fi rst records are given for B. gallicus
(Mulsant, 1842) from Corsica and the Midi-Pyrénées region of France, B. keithi
Miessen & Trichas, 2011 from the Greek island of Rhodes, and B. unicornis
(Schrank von Paula, 1789) from the Tuscany province of Italy
Forecasting ocean warming impacts on seabird demography: a case study on the European storm petrel
Bottom-up climatic forcing has been shown to be influential for a variety of marine
taxa, but evidence on seabird populations is scarce. Seasonal variation in environmental conditions
can have an indirect effect on subsequent reproduction, which, given the longevity and
single-brooding of seabirds, may affect population dynamics. Our study focuses on linking the
effect of oceanographic conditions (from 1991 to 2013) to the fecundity and consequently pop -
ulation growth rate of the Mediterranean subspecies of the European storm petrel Hydrobates
pelagicus melitensis. In this study, we examined 23 yr of > 5400 capture–mark−recaptures (CMR)
and modelled the probability of skipping reproduction as a function of oceanographic variables
using CMR models. We demonstrate that a decrease in sea surface temperature in the pre-breeding
period negatively influences skipping propensity, and therefore hypothesize that this behaviour
would have significant influence on population abundance over time. For this reason, we analysed
population growth as a function of skipping probability as affected by oceanographic
conditions. We used stochastic demographic models to forecast the fate of the population, and
evaluated contrasted environmental condition scenarios. As a result, we found that a decrease in
frequency of cold winter events would probably reduce skipping propensity, with a positive effect
on the population as a whole
Determining the Physical Properties of the B Stars I. Methodology and First Results
We describe a new approach to fitting the UV-to-optical spectra of B stars to
model atmospheres and present initial results. Using a sample of lightly
reddened stars, we demonstrate that the Kurucz model atmospheres can produce
excellent fits to either combined low dispersion IUE and optical photometry or
HST FOS spectrophotometry, as long as the following conditions are fulfilled:
1) an extended grid of Kurucz models is employed,
2) the IUE NEWSIPS data are placed on the FOS absolute flux system using the
Massa & Fitzpatrick (1999) transformation, and
3) all of the model parameters and the effects of interstellar extinction are
solved for simultaneously.
When these steps are taken, the temperatures, gravities, abundances and
microturbulence velocities of lightly reddened B0-A0 V stars are determined to
high precision. We also demonstrate that the same procedure can be used to fit
the energy distributions of stars which are reddened by any UV extinction curve
which can be expressed by the Fitzpatrick & Massa (1990) parameterization
scheme.
We present an initial set of results and verify our approach through
comparisons with angular diameter measurements and the parameters derived for
an eclipsing B star binary. We demonstrate that the metallicity derived from
the ATLAS 9 fits to main sequence B stars is essentially the Fe abundance. We
find that a near zero microturbulence velocity provides the best-fit to all but
the hottest or most luminous stars (where it may become a surrogate for
atmospheric expansion), and that the use of white dwarfs to calibrate UV
spectrophotometry is valid.Comment: 17 pages, including 2 pages of Tables and 6 pages of Figures.
Astrophysical Jounral, in pres
Far-UV FUSE spectroscopy of the OVI resonance doublet in Sand2 (WO)
We present Far-Ultraviolet Spectroscopic Explorer (FUSE) spectroscopy of Sand
2, a LMC WO-type Wolf-Rayet star, revealing the OVI resonance P Cygni doublet
at 1032-38A. These data are combined with HST/FOS ultraviolet and Mt Stromlo
2.3m optical spectroscopy, and analysed using a spherical, non-LTE,
line-blanketed code. Our study reveals exceptional stellar parameters:
T*=150,000K, v_inf=4100 km/s, log (L/Lo)=5.3, and Mdot=10^-5 Mo/yr if we adopt
a volume filling factor of 10%. Elemental abundances of C/He=0.7+-0.2 and
O/He=0.15(-0.05+0.10) by number qualitatively support previous recombination
line studies. We confirm that Sand 2 is more chemically enriched in carbon than
LMC WC stars, and is expected to undergo a supernova explosion within the next
50,000 yr.Comment: 17 pages, 4 figures, AASTeX preprint format. This paper will appear
in a special issue of ApJ Letters devoted to the first scientific results
from the FUSE missio
Second-order-like cluster-monomer transition within magnetic fluids and its impact upon the magnetic susceptibility
The low-field (below 5 Oe) ac and dc magnetic response of a magnetic fluid [MF] sample in the range of 305 to 360 K and 410 to 455 K was experimentally and theoretically investigated. We found a systematic deviation of Curie's law, which predicts a linear temperature dependence of inverse initial susceptibility in the range of our investigation. This finding, as we hypothesized, is due to the onset of a second-order-like cluster-to-monomer transition with a critical exponent which is equal to 0.50. The susceptibility data were well fitted by a modified Langevin function, in which cluster dissociation into monomers, at the critical temperature [T*], was included. In the ac experiments, we found that T* was reducing from 381.8 to 380.4 K as the frequency of the applied field increases from 123 to 173 Hz. In addition, our ac experiments confirm that only monomers respond for the magnetic behavior of the MF sample above T*. Furthermore, our Monte Carlo simulation and analytical results support the hypothesis of a thermal-assisted dissociation of chain-like structures
Linearization of nonlinear connections on vector and affine bundles, and some applications
A linear connection is associated to a nonlinear connection on a vector
bundle by a linearization procedure. Our definition is intrinsic in terms of
vector fields on the bundle. For a connection on an affine bundle our procedure
can be applied after homogenization and restriction. Several applications in
Classical Mechanics are provided
Characterizing the magnetic fields of the first tau Sco analogues
The B0.2 V magnetic star tau Sco stands out from the larger population of
massive OB stars due to its high X-ray activity, peculiar wind diagnostics and
complex magnetic field. Recently, Petit et al. 2011 presented the discovery of
the first two tau Sco analogues -- HD 66665 and HD 63425, identified by the
striking similarity of their UV spectra to that of tau Sco. ESPaDOnS and Narval
spectropolarimetric observations were obtained by the Magnetism in Massive
Stars CFHT and TBL Large Programs, in order to characterize the stellar and
magnetic properties of these stars. A magnetic field of similar surface
strength was found on both stars, reinforcing the connection between the
presence of a magnetic field and wind peculiarities. We present additional
phase-resolved observations secured by the MiMeS collaboration for HD 66665 in
order to measure its magnetic geometry, and correlate that geometry with
diagnostics of mass-loss.Comment: to appear in the proceedings of Stellar polarimetry: From birth to
death, Madison, USA, June 27 - June 30, 2011 (version 2 was updated to
correct a typo in the arXiv metadata
Experimental Quantum Cryptography With Classical Users
The exploit of quantum systems allows for insights that promise to
revolutionise information processing, although a main challenge for practical
implementations is technological complexity. Due to its feasibility, quantum
cryptography, which allows for perfectly secure communication, has become the
most prominent application of quantum technology. Nevertheless, this task still
requires the users to be capable of performing quantum operations, such as
state preparation or measurements in multiple bases. A natural question is
whether the users' technological requirements can be further reduced. Here we
demonstrate a novel quantum cryptography scheme, where users are fully
classical. In our protocol, the quantum operations are performed by an
untrusted third party acting as a server, which gives the users access to a
superimposed single photon, and the key exchange is achieved via
interaction-free measurements on the shared state. Our approach opens up new
interesting possibilities for quantum cryptography networks.Comment: Main Text (9 pages, 3 figures) + Appendix (19 pages, 2 figures
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