643 research outputs found
A new rebbachisaurid sauropod from the AptianâAlbian, Lower Cretaceous Rayoso Formation, NeuquĂ©n, Argentina
Rebbachisaurids are a group of basal diplodocimorph sauropods that diversified in Gondwana at the end of the Early
Cretaceous and the beginning of the Late Cretaceous. It is a group of great palaeobiogeographical interest, for it clearly
illustrates various processes of dispersal throughout Gondwana and to Laurasia prior to the breakup of Africa and South
America. However, the relationships within the group are still under discussion owing to the scarcity of cranial material
that would help clarify them. In the present paper we describe the new rebbachisaurid Lavocatisaurus agrioensis gen. et
sp. nov. from the AptianâAlbian (Lower Cretaceous) of NeuquĂ©n (Argentina). Remains have been recovered belonging
to an adult specimen (holotype) and two immature specimens (paratypes). Taken together, almost all the bones of the
taxon are represented, including most of the cranium. Lavocatisaurus agrioensis gen. et sp. nov. is the first rebbachisaurid
from Argentina with an almost complete cranium, making it possible to recognize differences with respect to
other rebbachisaurids, such as the highly derived Nigersaurus. Among its most notable characters are the presences of
a large preantorbital fenestra and maxillary teeth that are significantly larger than those of the dentary. Our phylogenetic
study places Lavocatisaurus amongst basal rebbachisaurids, as the sister lineage to Khebbashia (the clade formed by
Limaysaurinae + Rebbachisaurinae). This position, which is somewhat more derived than that previously suggested
for Comahuesaurus and Zapalasaurus (the Argentinean rebbachisaurids closest in geographical and geological terms),
reaffirms the presence of different basal rebbachisaurid lineages in the Early Cretaceous of Patagonia
Primera evidencia de dinosaurios ornitĂłpodos en la base de la FormaciĂłn Huincul (Cenomaniense Superior-Turoniense, Cuenca Neuquina, Argentina)
Se describe por primera vez la presencia de dinosaurios ornitĂłpodos en la base de la FormaciĂłn Huincul (Cenomaniense-Turoniense) de Agrio del Medio (NeuquĂ©n, Argentina). Se trata de una falange ungueal del pie bien conservada y de pequeño tamaño. Presenta una morfologĂa general en forma de garra, similar a la de los ornitĂłpodos basales que se han encontrado en el CretĂĄcico Superior de SudamĂ©rica, lo que le diferencia de las formas mĂĄs derivadas de iguanodontios con ungueal en forma de casco. Este descubrimiento es una nueva evidencia que los pequeños ornitĂłpodos basales se encontraban en la Cuenca Neuquina, al menos, desde el transito CretĂĄcico Inferior-Superior.
We describe for the first time the presence of ornithopod dinosaurs at the base of the Huincul Formation (Cenomanian-Turonian) of Agrio del Medio (Neuquén, Patagonia, Argentina). The specimen in question is a well-preserved and small phalanx toenail. It presents a general morphology in the form of a claw, similar to that of basal ornithopods that have been found in the Upper Cretaceous of South America. This differentiates it from the most derived iguanodontians, which have a hoof-shaped nail. This finding is new evidence than indicates that small basal ornithopods were in the Neuquén Basin at least since the transition of the Early-Late Cretaceous
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Session D7: Fishway with Two Entrance Locations: Understanding its importance for Iberian Barbel
Abstract
In recent years, in the Iberian Peninsula, many fish passes have been built and improved. To ensure the proper operation of these, it is essential to carry out an evaluation and subsequent monitoring, considering both biologic and hydraulic aspects. We analyze the performance of Iberian barbel âLuciobarbus bocagei (Steindachner, 1864)â in a technical fishway: pool and weir, with bottom orifice. It is located in the Josefina hydropower plant (Duero River, Valladolid, Spain). Fish ladder has two fish entrances: one in the turbine outlet channel and another in the natural river course. Both the most relevant hydraulic values (flow, velocity, volumetric energy dissipation) and biological parameters (movement pattern, attraction, entry and passage) were measured.
Biological assessment was conducted in the spawning season using PIT tag technology. The main influence on upstream movement was river discharge. There were no preferences between path selection; and ascent success and transit time were similar between two entrances.. Results highlight the importance of two access points for improve entrance and decrease migration delay
Origin and fate of a bloom of Skeletonema costatum during a winter upwelling/downwelling sequence in the RĂa de Vigo (NW Spain)
Original research paperThe onset, development and decay of a winter bloom of the marine diatom Skeletonema costatum
was monitored during a 10 d period in the coastal upwelling system of the RıŽa de Vigo (NW Spain).
The succession of upwelling, relaxation and downwelling-favorable coastal winds with a frequency
of 10 â20 d is a common feature of the NW Iberian shelf. The onset of the bloom occurred during an
upwelling-favorable 1â2 wk period under winter thermal inversion conditions. The subsequent 1â2 wk
coastal wind relaxation period allowed development of the bloom (gross primary production reached
8gCmâ2 dâ1) utilizing nutrients upwelled during the previous period. Finally, downwelling during
the following 1â2 wk period forced the decay of the bloom through a combination of cell sinking and
downward advection.Financial support came from the Spanish Ministerio de Ciencia y TecnologıŽa (MCyT) grant REN2000-0880-C02-01 and Xunta de Galicia grant PGIDT01MAR40201PN; a fellowship from the MCyT and the I3P-CSIC Program.Versión del editor0,98
Counteracting gradients of light and soil nutrients in the understorey of Mediterranean oak forests.
The forest canopy modifies the availability of resources (light, water, and soil nutrients)
in the understorey. In this paper we analyze the relationships between woody canopy
density, litter accumulation, and topsoil N and P availability in the understorey of two
oak forests: one in southern Portugal and the other in southern Spain. Both forests
persist on low-nutrient soils, particularly poor in P. We hypothesize that direct and
indirect effects of the canopy overstorey cause opposite gradients in the availability of
essential resources (light and key soil nutrients) in the understorey. In both studied
forests we found significant relationships between the overall canopy density, light availability,
topsoil litter accumulation, and the availability of N and P, which frequently
limit plant growth. Path analysis (by Shipleyâs d-sep method) showed that the available
data were consistent with the proposed causal model. The average values of soil variables
at the end quartiles of the light-availability gradient were compared. Results showed
large differences in litter accumulation (~30Ă) and available-N and -P topsoil concentrations
(~3Ă) in the Spanish forest (with the wider environmental gradient). Furthermore,
P increased from the âvery lowâ range to the âlowâ or even the âoptimumâ range of
availability (according to standard plant growth criteria), which suggests potential effects
on the growth of the understorey plant species. We conclude that the counteracting
gradients of the essential resources -light and nutrients- in the forest understorey
resulted from direct and indirect effects of the canopy overstorey, respectively. We suggest
that these counteracting effects of the woody canopy on essential resources of different
nature must be considered when interpreting the patterns of understorey plant populations
and communities.The spanish MEC (CGL2005-05830-C03-01-BOS, DINAMED project) and the Portuguese FCT(SFRH/BD/8322/2002 grant to SMM)supported the research.Peer reviewe
Inter-hemispheric EEG coherence analysis in Parkinson's disease : Assessing brain activity during emotion processing
Parkinsonâs disease (PD) is not only characterized by its prominent motor symptoms but also associated with disturbances in cognitive and emotional functioning. The objective of the present study was to investigate the influence of emotion processing on inter-hemispheric electroencephalography (EEG) coherence in PD. Multimodal emotional stimuli (happiness, sadness, fear, anger, surprise, and disgust) were presented to 20 PD patients and 30 age-, education level-, and gender-matched healthy controls (HC) while EEG was recorded. Inter-hemispheric coherence was computed from seven homologous EEG electrode pairs (AF3âAF4, F7âF8, F3âF4, FC5âFC6, T7âT8, P7âP8, and O1âO2) for delta, theta, alpha, beta, and gamma frequency bands. In addition, subjective ratings were obtained for a representative of emotional stimuli. Interhemispherically, PD patients showed significantly lower coherence in theta, alpha, beta, and gamma frequency bands than HC during emotion processing. No significant changes were found in the delta frequency band coherence. We also found that PD patients were more impaired in recognizing negative emotions (sadness, fear, anger, and disgust) than relatively positive emotions (happiness and surprise). Behaviorally, PD patients did not show impairment in emotion recognition as measured by subjective ratings. These findings suggest that PD patients may have an impairment of inter-hemispheric functional connectivity (i.e., a decline in cortical connectivity) during emotion processing. This study may increase the awareness of EEG emotional response studies in clinical practice to uncover potential neurophysiologic abnormalities
Geochemical vs. microbial approach to the new production of the coastal upwelling system of the RĂa de Vigo (NW Spain)
Symposium GLOBECâIMBER España, Valencia, 28-30 marzo 2007The fate of the inorganic and organic N trapped in the coastal upwelling system of RĂa de Vigo (NW Spain), accumulation/export versus production/ consumption, was studied at the short timeâscale (2â4 d) during July 2002. A transient geochemical box model was applied to the measured residual currents and concentrations of inorganic (NT), dissolved (DON) and particulate (PON) organic N to obtain the i) net balance of inputs minus outputs (i â o); ii) the net accumulation (V·dN/dt); and iii) the net ecosystem production (NEP) of NT, DON and PON. The average NEP during July (107 mg N m-2 d-1) indicates an autotrophic metabolism of the rĂa. About 25% of this material was exported to the shelf and the remaining 75% was transferred to the sediments or promoted to higher trophic levels. Measurements of oxygen production (Pg) and respiration (R) were performed in a single site twice a week at five depths. In addition, microzooplankton grazing and sedimentation rates were measured for first time in the RĂa de Vigo. The high grazing rates observed reduces the efficiency of the rĂa to transfer organic matter directly from phytoplankton to the metazoans Comparison of the metabolic state of the RĂa de Vigo derived from these in vitro measurements (Pg, R, grazing and sedimentation) and the in situ geochemical budget shows that they agree in 2 of the 3 study cases. Both methods are complementary and their simultaneous application allows obtaining a better knowledge of coastal upwelling ecosystems functioningN
Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC
The uncertainty on the calorimeter energy response to jets of particles is
derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the
calorimeter response to single isolated charged hadrons is measured and
compared to the Monte Carlo simulation using proton-proton collisions at
centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009
and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter
response to specific types of particles (positively and negatively charged
pions, protons, and anti-protons) is measured and compared to the Monte Carlo
predictions. Finally, the jet energy scale uncertainty is determined by
propagating the response uncertainty for single charged and neutral particles
to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3%
for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table,
submitted to European Physical Journal
Standalone vertex ïŹnding in the ATLAS muon spectrometer
A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at âs = 7 TeV collected with the ATLAS detector at the LHC during 2011
Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC
Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H âÎł Îł, H â Z Zâ â4l and H âW Wâ âlÎœlÎœ. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of âs = 7 TeV and âs = 8 TeV, corresponding to an integrated luminosity of about 25 fbâ1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined ïŹts probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson
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