45 research outputs found
Bioclimatology, structure, and conservation perspectives of Quercus pyrenaica, Acer opalus subsp. Granatensis, and Corylus avellana deciduous forests on Mediterranean bioclimate in the South-Central part of the Iberian Peninsula
The plant variability in the southern Iberian Peninsula consists of around 3500 different taxa due to its high bioclimatic, geographic, and geological diversity. The deciduous forests in the southern Iberian Peninsula are located in regions with topographies and specific bioclimatic conditions that allow for the survival of taxa that are typical of cooler and wetter bioclimatic regions and therefore represent the relict evidence of colder and more humid paleoclimatic conditions. The floristic composition of 421 samples of deciduous forests in the south-central part of the Iberian Peninsula were analyzed. The ecological importance index (IVI) was calculated, where the most important tree species were Quercuspyrenaica, Aceropalus subsp. Granatensis, and Corylusavellana. These species are uncommon in the south-central part of the Iberian Peninsula, forming forests of little extension. An analysis of the vertical distribution of the species (stratum) shows that the majority of the species of stratum 3 (hemicriptophics, camephytes, geophites, and nanophanerophytes) are characteristic of deciduous forests, and their presence is positively correlated with high values of bioclimatic variables related to humidity and presence of water in the soil (nemoral environments), while they are negatively correlated with high values of bioclimatic variables related to high temperatures, evapotranspiration, and aridity. This work demonstrates that several characteristic deciduous forest taxa are more vulnerable to disappearance due to the loss of their nemoral conditions caused by gaps in the tree or shrub canopy. These gaps lead to an increase in evapotranspiration, excess insolation, and a consequent loss of water and humidity in the microclimatic conditions.info:eu-repo/semantics/publishedVersio
Triple oral beta-lactam containing therapy for Buruli ulcer treatment shortening
The potential use of clinically approved beta-lactams for Buruli ulcer (BU) treatment was investigated with representative classes analyzed in vitro for activity against Mycobacterium ulcerans. Beta-lactams tested were effective alone and displayed a strong synergistic profile in combination with antibiotics currently used to treat BU, i.e. rifampicin and clarithromycin; this activity was further potentiated in the presence of the beta-lactamase inhibitor clavulanate. In addition, quadruple combinations of rifampicin, clarithromycin, clavulanate and beta-lactams resulted in multiplicative reductions in their minimal inhibitory concentration (MIC) values. The MIC of amoxicillin against a panel of clinical isolates decreased more than 200-fold within this quadruple combination. Amoxicillin/clavulanate formulations are readily available with clinical pedigree, low toxicity, and orally and pediatric available; thus, supporting its potential inclusion as a new anti-BU drug in current combination therapies
Localization of the cannabinoid type-1 receptor in subcellular astrocyte compartments of mutant mouse hippocampus
Astroglial type‐1 cannabinoid (CB1) receptors are involved in synaptic transmission, plasticity and behavior by interfering with the so‐called tripartite synapse formed by pre‐ and post‐synaptic neuronal elements and surrounding astrocyte processes. However, little is known concerning the subcellular distribution of astroglial CB1 receptors. In particular, brain CB1 receptors are mostly localized at cells' plasmalemma, but recent evidence indicates their functional presence in mitochondrial membranes. Whether CB1 receptors are present in astroglial mitochondria has remained unknown. To investigate this issue, we included conditional knock‐out mice lacking astroglial CB1 receptor expression specifically in glial fibrillary acidic protein (GFAP)‐containing astrocytes (GFAP‐CB1‐KO mice) and also generated genetic rescue mice to re‐express CB1 receptors exclusively in astrocytes (GFAP‐CB1‐RS). To better identify astroglial structures by immunoelectron microscopy, global CB1 knock‐out (CB1‐KO) mice and wild‐type (CB1‐WT) littermates were intra‐hippocampally injected with an adeno‐associated virus expressing humanized renilla green fluorescent protein (hrGFP) under the control of human GFAP promoter to generate GFAPhrGFP‐CB1‐KO and ‐WT mice, respectively. Furthermore, double immunogold (for CB1) and immunoperoxidase (for GFAP or hrGFP) revealed that CB1 receptors are present in astroglial mitochondria from different hippocampal regions of CB1‐WT, GFAP‐CB1‐RS and GFAPhrGFP‐CB1‐WT mice. Only non‐specific gold particles were detected in mouse hippocampi lacking CB1 receptors. Altogether, we demonstrated the existence of a precise molecular architecture of the CB1 receptor in astrocytes that will have to be taken into account in evaluating the functional activity of cannabinergic signaling at the tripartite synapse.Molecular Physiolog
Reconstruction of events recorded with the surface detector of the Pierre Auger Observatory
Cosmic rays arriving at Earth collide with the upper parts of the atmosphere, thereby inducing extensive air showers. When secondary particles from the cascade arrive at the ground, they are measured by surface detector arrays. We describe the methods applied to the measurements of the surface detector of the Pierre Auger Observatory to reconstruct events with zenith angles less than 60o using the timing and signal information recorded using the water-Cherenkov detector stations. In addition, we assess the accuracy of these methods in reconstructing the arrival directions of the primary cosmic ray particles and the sizes of the induced showers
Ultrahigh energy neutrinos at the pierre auger observatory
The observation of ultrahigh energy neutrinos (UHEs) has become a priority in experimental astroparticle physics. UHEs can be detected with a variety of techniques. In particular, neutrinos can interact in the atmosphere (downward-going ) or in the Earth crust (Earth-skimming ), producing air showers that can be observed with arrays of detectors at the ground. With the surface detector array of the Pierre Auger Observatory we can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e., after having traversed a large amount of atmosphere). In this work we review the procedure and criteria established to search for UHEs in the data collected with the ground array of the Pierre Auger Observatory.This includes Earth-skimming as well as downward-going neutrinos. No neutrino candidates have been found, which allows us to place competitive limits to the diffuse flux of UHEs in the EeV range and above
Description of Atmospheric Conditions at the Pierre Auger Observatory using the Global Data Assimilation System (GDAS)
Atmospheric conditions at the site of a cosmic ray observatory must be known
for reconstructing observed extensive air showers. The Global Data Assimilation
System (GDAS) is a global atmospheric model predicated on meteorological
measurements and numerical weather predictions. GDAS provides
altitude-dependent profiles of the main state variables of the atmosphere like
temperature, pressure, and humidity. The original data and their application to
the air shower reconstruction of the Pierre Auger Observatory are described. By
comparisons with radiosonde and weather station measurements obtained on-site
in Malarg\"ue and averaged monthly models, the utility of the GDAS data is
shown
Endemic hemicryptophyte grasslands of the high mountains of the Caribbean
20 páginas, 5 figuras, 2 tablas.Although there are numerous studies on the floristic composition of the Andean and Caribbean grasslands, there are limited information from a phytosociological point of view. This work
therefore aims to highlight the differences in this important vegetation type in these two biodiversity hotspots to gain a better understanding of their floristic and vegetational richness. The floristic
composition of Andean grasslands (Ecuador) and the island of Hispaniola is also studied. The reason for this comparative analysis of Andean and Caribbean territories is their tropical character and
their bioclimatic similarities. The comparative analysis of Peruvian Andean and Colombian grasslands is based on floristic knowledge from the literature, our inventories on the island of Hispaniola,
and the works of Peguero. We applied the phytosociological methodology of Braun-Blanquet and
the code of phytosociological nomenclature. We performed a statistical analysis to verify the differences between both community types using the statistical packages PAST© and CAP3. The comparative analysis of Andean and Caribbean grasslands shows a clear floristic and biogeographical
differentiation and reveals that the only ecological character they share is their high-mountain attribute. In the Caribbean these communities are found only on the island of Hispaniola (Dominican
Republic) in the Central biogeographic sector, Central subprovince, Hispaniola province. These
grasslands are exclusive to Hispaniola and have a high rate of endemics. We propose the following
new syntaxa: the association Hyperico constanzae-Danthonietum domingensis, the alliance Hieracio
domingensis-Deschampsion domingensis, the order Danthonietalia domingensis, and the class Deschampsio-Danthonietea domingensis. We found high biodiversity values for Andean and Caribbean
areas. This is due to the intense anthropic activity on the island of Hispaniola, which has led to a
high percentage of naturalized plants.Samplings were taken within the context of three projects by the AECI (Spanish International Cooperation Agency) from 2005 to 2007
A predictive numerical model for potential mapping of the gas hydrate stability zone in the Gulf of Cadiz
This paper presents a computational model for mapping the regional 3D distribution in which seafloor
gas hydrates would be stable, that is carried out in a Geographical Information System (GIS) environment.
The construction of the model is comprised of three primary steps, namely: (1) the construction of
surfaces for the various variables based on available 3D data (seafloor temperature, geothermal gradient
and depth-pressure); (2) the calculation of the gas function equilibrium functions for the various
hydrocarbon compositions reported from hydrate and sediment samples; and (3) the calculation of the
thickness of the hydrate stability zone. The solution is based on a transcendental function, which is
solved iteratively in a GIS environment.
The model has been applied in the northernmost continental slope of the Gulf of Cadiz, an area where an
abundant supply for hydrate formation, such as extensive hydrocarbon seeps, diapirs and fault structures,
is combined with deep undercurrents and a complex seafloor morphology. In the Gulf of Cadiz, the
model depicts the distribution of the base of the gas hydrate stability zone for both biogenic and thermogenic
gas compositions, and explains the geometry and distribution of geological structures derived
from gas venting in the Tasyo Field (Gulf of Cadiz) and the generation of BSR levels on the upper
continental slope