600,287 research outputs found
The beetles of St. Lucia, Lesser Antilles (Insecta: Coleoptera): diversity and distributions
The published beetle fauna of the island of St. Lucia is summarized. It contains 135 genera, and 175 species in 25 families. Four species are accidentally introduced by human activities. Twenty three species are endemic (restricted) to the island. Twenty seven species on St. Lucia are shared only with other islands of the Lesser Antilles, and 22 species are widespread Antilles endemics. The remaining 56.6% of the fauna is otherwise mostly one which is widely distributed in the Antilles and the Neotropics. This suggests that it is mostly an immigrant fauna originating in the continental Neotropics. Undoubtedly, the actual numbers of species on St. Lucia are many times higher than now reported and may originally have been as high as around 1400 species. Of the St. Lucia species known to occur on other islands, the largest numbers are shared with Guadeloupe (102), St. Vincent (79), and Martinique (55)
Direct measurement of tree height provides different results on the assessment of LiDAR accuracy
open8noopenSibona, Emanuele; Vitali, Alessandro; Meloni, Fabio; Caffo, Lucia; Dotta, Alberto; Lingua, Emanuele; Motta, Renzo; Garbarino, MatteoSibona, Emanuele; Vitali, Alessandro; Meloni, Fabio; Caffo, Lucia; Dotta, Alberto; Lingua, Emanuele; Motta, Renzo; Garbarino, Matte
Galaxy Formation Theory
We review the current theory of how galaxies form within the cosmological
framework provided by the cold dark matter paradigm for structure formation.
Beginning with the pre-galactic evolution of baryonic material we describe the
analytical and numerical understanding of how baryons condense into galaxies,
what determines the structure of those galaxies and how internal and external
processes (including star formation, merging, active galactic nuclei etc.)
determine their gross properties and evolution. Throughout, we highlight
successes and failings of current galaxy formation theory. We include a review
of computational implementations of galaxy formation theory and assess their
ability to provide reliable modelling of this complex phenomenon. We finish
with a discussion of several "hot topics" in contemporary galaxy formation
theory and assess future directions for this field.Comment: 58 pages, to appear in Physics Reports. This version includes minor
corrections and a handful of additional reference
Carbon portfolio management
The aim of the European Union's Emissions Trading Scheme (EU ETS) is that by 2020, emissions from sectors covered by the EU ETS will be 21% lower than in 2005. In addition to large CO 2 emitting companies covered by the scheme, other participants have entered the market with a view of using emission allowances for the diversification of their investment portfolios. The performance of this asset as a stand alone investment and its portfolio diversification implications will be investigated in this paper. Our results indicate that the market views Phases 1, 2, and 3 European Union allowance futures as unattractive as stand alone investments. In a portfolio context, in Phase 1, once the short-selling option is added, there are considerable portfolio benefits. However, our results indicate that these benefits only existed briefly during the pilot stage of the EU ETS. There is no evidence to suggest portfolio diversification benefits exist for Phase 2 or the early stages of Phase 3
Equilibrium statistical mechanics for incomplete nonextensive statistics
The incomplete nonextensive statistics in the canonical and microcanonical
ensembles is explored in the general case and in a particular case for the
ideal gas. By exact analytical results for the ideal gas it is shown that
taking the thermodynamic limit, with being an extensive variable of
state, the incomplete nonextensive statistics satisfies the requirements of
equilibrium thermodynamics. The thermodynamical potential of the statistical
ensemble is a homogeneous function of the first degree of the extensive
variables of state. In this case, the incomplete nonextensive statistics is
equivalent to the usual Tsallis statistics. If is an intensive variable of
state, i.e. the entropic index is a universal constant, the requirements of
the equilibrium thermodynamics are violated.Comment: 7 page
The origin of redshift asymmetries: How LambdaCDM explains anomalous redshift
Several authors have found a statistically significant excess of galaxies
with higher redshifts relative to the group centre, so-called discordant
redshifts, in particular in groups where the brightest galaxy, identified in
apparent magnitudes, is a spiral. Our aim is to explain the observed redshift
excess. We use a semi-analytical galaxy catalogue constructed from the
Millennium Simulation to study redshift asymmetries in spiral-dominated groups
in the Lambda cold dark matter (LambdaCDM) cosmology. We show that discordant
redshifts in small galaxy groups arise when these groups are gravitationally
unbound and the dominant galaxy of the group is misidentified. The redshift
excess is especially significant when the apparently brightest galaxy can be
identified as a spiral, in full agreement with observations. On the other hand,
the groups that are gravitationally bound do not show a significant redshift
asymmetry. When the dominant members of groups in mock catalogues are
identified by using the absolute B-band magnitudes, our results show a small
blueshift excess. This result is due to the magnitude limited observations that
miss the faint background galaxies in groups. When the group centre is not
correctly identified it may cause the major part of the observed redshift
excess. If the group is also gravitationally unbound, the level of the redshift
excess becomes as high as in observations. There is no need to introduce any
"anomalous" redshift mechanism to explain the observed redshift excess.
Further, as the Friends-of-Friends percolation algorithm picks out the
expanding parts of groups, in addition to the gravitationally bound group
cores, group catalogues constructed in this way cannot be used as if the groups
are purely bound systems.Comment: Accepted for publication in A&
Reconciling with the Past: Ana Lucia Araujo’s Lecture on Coming to Terms with the Past When Monuments Are Taken Down
On Thursday, November 2nd, Howard University History Professor Ana Lucia Araujo visited Gettysburg College to give a lecture titled “Slavery, Memory, and Reparations: Coming to Terms with the Past When Monuments Are Taken Down.” The historian, author, and professor talked about the history of slavery as well as the concepts of memory and reparations. One form of reparations discussed recently has been the removal of Confederate monuments in the United States, which has been heavily debated for years. [excerpt
Formation, Evolution and Properties of Isolated Field Elliptical Galaxies
[Abridged] We study the properties, evolution and formation mechanisms of
isolated field elliptical galaxies. We create a mock catalogue of isolated
field elliptical galaxies from the Millennium Simulation Galaxy Catalogue, and
trace their merging histories. The formation, identity and assembly redshifts
of simulated isolated and non-isolated elliptical galaxies are studied and
compared. Observational and numerical data are used to compare age, mass, and
the colour-magnitude relation. Our results, based on simulation data, show that
almost seven per cent of all elliptical galaxies brighter than -19mag in B-band
can be classified as isolated field elliptical galaxies. Isolated field
elliptical galaxies show bluer colours than non-isolated elliptical galaxies
and they appear younger, in a statistical sense, according to their mass
weighted age. Isolated field elliptical galaxies also form and assemble at
lower redshifts compared to non-isolated elliptical galaxies. About 46 per cent
of isolated field elliptical galaxies have undergone at least one major merging
event in their formation history, while the same fraction is only about 33 per
cent for non-isolated ellipticals. The mean time of the last major merging is z
= 0.6 or 6 Gyrs ago for isolated ellipticals, while non-isolated ellipticals
experience their last major merging significantly earlier at z = 1.1 or 8 Gyrs
ago. After inspecting merger trees of simulated isolated field elliptical
galaxies, we conclude that three different, yet typical formation mechanisms
can be identified: solitude, coupling and cannibalism. Our results also predict
a previously unobserved population of blue, dim and light galaxies that fulfill
observational criteria to be classified as isolated field elliptical galaxies.
This separate population comprises about 26 per cent of all IfEs.Comment: Accepted for publication in MNRAS, 19 pages, 16 figure
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