270 research outputs found
A summary of the endemic beetle genera of the West Indies (Insecta: Coleoptera); bioindicators of the evolutionary richness of this Neotropical archipelago
The Caribbean Islands (or the West Indies) are recognized as one of the leading global biodiversity hot
spots. This is based on data on species, genus, and family diversity for vascular plants and non-marine vertebrates. This
paper presents data on genus level endemicity for the most speciose (but less well publicised) group of terrestrial
animals: the beetles, with 205 genera (in 25 families) now recognized as being endemic (restricted) to the West Indies.
The predominant families with endemic genera are Cerambycidae (41), Chrysomelidae (28), Curculionidae (26), and
Staphylinidae (25). This high level of beetle generic endemicity can be extrapolated to suggest that a total of about
700 genera of all insects could be endemic to the West Indies. This far surpasses the total of 269 endemic genera of all
plants and non-marine vertebrates, and reinforces the biodiversity richness of the insect fauna of the West Indies.Las islas del Caribe (o Indias Occidentales) son reconocidas como uno de los principales hotspots de la
biodiversidad global. Esto se basa en datos sobre la diversidad de especies, géneros y familias de plantas vasculares y
vertebrados no-marinos. Este trabajo presenta datos sobre la endemicidad a nivel genérico para el más especioso (pero
menos popularizado) grupo de animales terrestres: los escarabajos, con 205 géneros (en 25 familias) reconocidos al
presente como endémicos (restringidos) a las Indias Occidentales. Las familias predominantes en géneros endémicos
son Cerambycidae (41), Chrysomelidae (28), Curculionidae (26) y Staphylinidae (25). Este alto nivel de endemicidad
genérica en los escarabajos puede extrapolarse a sugerir que alrededor de 700 géneros pudieran ser endémicos entre
todos los insectos de las Indias Occidentales. Esto sobrepasa ampliamente el total de 269 géneros endémicos de
plantas y vertebrados no-marinos y refuerza la riqueza en biodiversidad de la fauna de insectos en las Indias Occidentales
La formació professional ara mateix
Abstract not availabl
Minorca, an exotic Balearic island (western Mediterranean)
Despite forming part of the Balearic group of islands, Minorca differs stratigraphically and structurally from Majorca and Ibiza: i) Paleozoic rocks are abundant in Minorca but are very scarce in Majorca and are absent in Ibiza. Eocene-Oligocene sediments are virtually absent in Minorca but crop out extensively in Majorca, ii) Contractional structures in Minorca differ in direction (aligned SW-NE in Majorca and Ibiza and N-S in Minorca) and in age from those in Majorca and Ibiza. In addition, Paleozoic deposits of Minorca do not correlate with those of Sardinia, where in addition the Triassic sediments are not very abundant. Contractional deformation in Sardinia is in part older (late Eocene-early Miocene) than in Minorca (early Miocene?). Given its Neogene clockwise rotation, Minorca cannot be considered a small block dragged by the early Miocene counter clockwise rotation of the Corsica-Sardinia block. Furthermore, the Paleozoic and Mesozoic stratigraphy of Minorca (siliciclasticlate Paleozoic rocks, Triassic Germanic facies and Jurassic carbonates) has affinities with that of the southern part of the Catalan Coastal Ranges. Thus, of all the Balearic islands, Minorca seems to have traveled the farthest during the Valencia Trough rifting with the result that it resembles an exotic island forming part of the Balearic foreland
Effects of margin-parallel shortening and density contrasts on back-arc extension during subduction: Experimental insights and possible application to Anatolia
International audienceSo as to investigate the parameters influencing subduction and back-arc extension, we have done three series of laboratory experiments (32 in all) on physical models. Each model consisted of adjacent oceanic and continental plates, floating on an asthenosphere. In experiments of Series A, a wide rigid piston, moving horizontally, controlled the rate of convergence of the oceanic and continental plates, whereas, in Series B or C, a wide or narrow piston produced lateral compression, parallel to the continent-ocean boundary (COB) and perpendicular to the subduction direction. The parameters that we tested were (1) the velocity of plate convergence (Series A), (2) the width of the compressing piston (Series B and C), and (3) the density ratio between oceanic and continental plates (Series B and C). This density ratio was a key factor. For a ratio of 1.4, the amount of extension in the continental plate increased regularly throughout time; for a ratio of 1.3, the extension remained small, until the piston stopped moving laterally; and for a ratio of 1.1, there was little or no extension. The width of the compressing piston had a smaller effect, although a narrow piston provided more space, into which the continental plate could extend. One possible application of our models is to Anatolia. Despite similar geological settings, the areas north of the Hellenic and Cyprus subduction zones differ, in that extension is large in the former and much smaller in the latter. We suggest that one of the main driving forces for Aegean extension may have been a high density ratio between subducting oceanic lithosphere and a Hellenic-Balkanic upper plate
Conductance oscillations of a spin-orbit stripe with polarized contacts
We investigate the linear conductance of a stripe of spin-orbit interaction
in a 2D electron gas; that is, a 2D region of length along the transport
direction and infinite in the transverse one in which a spin-orbit interaction
of Rashba type is present. Polarization in the contacts is described by means
of Zeeman fields. Our model predicts two types of conductance oscillations:
Ramsauer oscillations in the minority spin transmission, when both spins can
propagate, and Fano oscillations when only one spin propagates. The latter are
due to the spin-orbit coupling with quasibound states of the non propagating
spin. In the case of polarized contacts in antiparallel configuration Fano-like
oscillations of the conductance are still made possible by the spin orbit
coupling, even though no spin component is bound by the contacts. To describe
these behaviors we propose a simplified model based on an ansatz wave function.
In general, we find that the contribution for vanishing transverse momentum
dominates and defines the conductance oscillations. Regarding the oscillations
with Rashba coupling intensity, our model confirms the spin transistor
behavior, but only for high degrees of polarization. Including a position
dependent effective mass yields additional oscillations due to the mass jumps
at the interfaces.Comment: 8.5 pages, 9 figure
Exchange-bias phenomenon: The role of the ferromagnetic spin strucutre
The exchange bias of antiferromagnetic-ferromagnetic (AFM-FM) bilayers is found to be strongly dependent on the ferromagnetic spin configuration. The widely accepted inverse proportionality of the exchange bias field with the ferromagnetic thickness is broken in FM layers thinner than the FM correlation length. Moreover, an anomalous thermal dependence of both exchange bias field and coercivity is also found. A model based on springlike domain walls parallel to the AFM-FM interface quantitatively accounts for the experimental results and, in particular, for the deviation from the inverse proportionality law. These results reveal the active role the ferromagnetic spin structure plays in AFM-FM hybrids which leads to a new paradigm of the exchange bias phenomenon
Interference of Fano-Rashba conductance dips
We study the interference of two tunable Rashba regions in a quantum wire
with one propagating mode. The transmission dips (Fano-Rashba dips) of the two
regions either cross or anti cross depending on the distance between the two
regions. For large separations we find Fabry-P\'erot oscillations due to the
interference of forwards and backwards propagating modes. At small separations
overlapping evanescent modes play a prominent role, leading to an enhanced
transmission and destroying the conductance dip. Analytical expressions in
scattering-matrix theory are given and the relevance of the interference effect
in a device is discussed.Comment: 10 pages, 4 embedded figure
Neonatal-onset multisystem inflammatory disease responsive to interleukin-1 beta inhibition
BACKGROUND:Neonatal-onset multisystem inflammatory disease is characterized by fever, urticarial rash, aseptic meningitis, deforming arthropathy, hearing loss, and mental retardation. Many patients have mutations in the cold-induced autoinflammatory syndrome 1 (CIAS1) gene, encoding cryopyrin, a protein that regulates inflammation.METHODS:We selected 18 patients with neonatal-onset multisystem inflammatory disease (12 with identifiable CIAS1 mutations) to receive anakinra, an interleukin-1-receptor antagonist (1 to 2 mg per kilogram of body weight per day subcutaneously). In 11 patients, anakinra was withdrawn at three months until a flare occurred. The primary end points included changes in scores in a daily diary of symptoms, serum levels of amyloid A and C-reactive protein, and the erythrocyte sedimentation rate from baseline to month 3 and from month 3 until a disease flare.RESULTS:All 18 patients had a rapid response to anakinra, with disappearance of rash. Diary scores improved (P<0.001) and serum amyloid A (from a median of 174 mg to 8 mg per liter), C-reactive protein (from a median of 5.29 mg to 0.34 mg per deciliter), and the erythrocyte sedimentation rate decreased at month 3 (all P<0.001), and remained low at month 6. Magnetic resonance imaging showed improvement in cochlear and leptomeningeal lesions as compared with baseline. Withdrawal of anakinra uniformly resulted in relapse within days; retreatment led to rapid improvement. There were no drug-related serious adverse events.CONCLUSIONS:Daily injections of anakinra markedly improved clinical and laboratory manifestations in patients with neonatal-onset multisystem inflammatory disease, with or without CIAS1 mutations
Aquatic Organic Matter in the Seine Basin: Sources, Spatio-Temporal Variability, Impact of Urban Discharges and Influence on Micro-pollutant Speciation
International audienc
- …