4,888 research outputs found
Avaliação da predação de rato-preto Rattus rattus nas crias de cagarra Calonectris diomedea borealis na Ilha da Berlenga
Berlengas Archipelago is the most important area in mainland Portugal for breeding seabirds. The archipelago hosts the only known breeding population of the vulnerable Cory’s Shearwater Calonectris diomedea borealis in mainland Portuguese coastal waters. Although this population has already been the subject of many studies, little is known about its interaction with black rat Rattus rattus. Black rat and rabbit Oryctolagus cuniculus are the only introduced mammals on the island, and the first is listed as one of the main predators of Cory’s Shearwater chicks. This study aimed to 1) evaluate the activity of black rat in two Cory’s Shearwater colonies and 2) report events of predation on chicks. For this, 54 and 20 nests were monitored daily in the colonies of Melreu and Furado Seco, respectively, between July 24 and August 6. Meanwhile, 16 photographic traps were installed within or at the entrance of 29 different nests in order to monitor rats’ activity. Despite not having obtained any record from direct predation of black rat, 2 chicks disappeared from the nest (with no photo trap) with a strong likelihood of being predated. Although in Melreu have been noticed a strong decrease in activity of black rat during development of chicks and Furado Seco not, the data presented here suggest a greater and more prolonged activity of rat at the second, which may indicate it’s under greater predatory pressure. Finnally it was found some evidences on possible impact by yellow-legged-gull on Cory’s shearwater chicks
A VLT/VIMOS view of two multiple-cluster systems: structure and galaxy properties
We analysed spectroscopic data obtained with VLT-VIMOS for two
multiple-cluster systems, PLCKG and PLCKG, discovered
via their thermal Sunyaev-Zel'dovich signal by . Combining the Optical
spectroscopy, for the redshift determination, and photometric data from galaxy
surveys (SDSS, WISE, DESI), we were able to study the structure of the two
multiple-cluster systems, to determine their nature and the properties of their
member galaxies. We found that the two systems are populated mainly with
passive galaxies and that PLCKG consists of a pair of clusters at
redshift and a background isolated cluster at , whereas
the system PLCKG is a chance association of three independent
clusters at redshifts , , and . We also find
evidence for remaining star formation activity in the highest-redshift cluster
of PLCKG, at .Comment: 12 pages, 9 Figures, 5 Tables. Submitted to A&A, comments are welcom
A Charge-Sensitive Amplifier Associated with APD or PMT for Positron Emission Tomography Scanners
to be presented at the 32nd International Convention MIPRO (Microeectronics, Electronics, and Electronic Technology (MEET)), Opatija, Croatia, May 25-29 2009We present a Charge-Sensitive Amplifier (CSA) to be coupled with a 511-KeV 2-photon detector for positron emission tomography scanners. The circuit has been designed to be associated with an Avalanche Photodiode (APD) or Photo-Multiplier Tube (PMT) with large capacitance. It is a two-stage structure. The input stage consists of a foldedcascode fully-differential part and a common-mode feedback (CMFB) circuit. The output stage employs complementary source followers. The amplifier has been designed in a 0.35μm BiCMOS process with optimization of noise and speed performances to meet specific constraints. Its main characteristics evaluated by post-layout simulations are: 70-dB DC gain, 4.6-GHz GBW, 20-ns peaking time for pulsed stimulus, 3900-electron equivalent input noise charge (ENC), 135-mW power consumption at 3.5 V supply
Transformation Mojette en 3D : mise en oeuvre et application en synthèse d'images
Dans ce papier, l'extension de la transformation Mojette en 3D est présentée. La transformation possède des propriétés très similaires à sa version 2D (algorithmes et complexité opératoire). La description des plans de projections doit toutefois être réalisée avec soin. Les conditions de reconstructibilité d'un volume à partir d'un ensemble discret de plans de projection sont présentées. On compare ensuite le taux de redondance produit entre versions 2D et 3D. L'application à la synthèse d'image est enfin exposée et semble prometteuse
Transport Phenomena and Structuring in Shear Flow of Suspensions near Solid Walls
In this paper we apply the lattice-Boltzmann method and an extension to
particle suspensions as introduced by Ladd et al. to study transport phenomena
and structuring effects of particles suspended in a fluid near sheared solid
walls. We find that a particle free region arises near walls, which has a width
depending on the shear rate and the particle concentration. The wall causes the
formation of parallel particle layers at low concentrations, where the number
of particles per layer decreases with increasing distance to the wall.Comment: 14 pages, 14 figure
Pulse Shape Analysis with scintillating bolometers
Among the detectors used for rare event searches, such as neutrinoless Double
Beta Decay (0DBD) and Dark Matter experiments, bolometers are very
promising because of their favorable properties (excellent energy resolution,
high detector efficiency, a wide choice of different materials used as
absorber, ...). However, up to now, the actual interesting possibility to
identify the interacting particle, and thus to greatly reduce the background,
can be fulfilled only with a double read-out (i.e. the simultaneous and
independent read out of heat and scintillation light or heat and ionization).
This double read-out could greatly complicate the assembly of a huge,
multi-detector array, such as CUORE and EURECA. The possibility to recognize
the interacting particle through the shape of the thermal pulse is then clearly
a very interesting opportunity.
While detailed analyses of the signal time development in purely thermal
detectors have not produced so far interesting results, similar analyses on
macro-bolometers (10-500 g) built with scintillating crystals showed that
it is possible to distinguish between an electron or -ray and an
particle interaction (i.e. the main source of background for 0DBD
experiments based on the bolometric technique). Results on pulse shape analysis
of a CaMoO crystal operated as bolometer is reported as an example. An
explanation of this behavior, based on the energy partition in the heat and
scintillation channels, is also presented.Comment: Presented at the 14th International Workshop on Low Temperature
Detectors, proceedings to be published in the Journal of Low Temperature
Physic
Aberrant Cortical Activity In Multiple GCaMP6-Expressing Transgenic Mouse Lines
Transgenic mouse lines are invaluable tools for neuroscience but as with any technique, care must be taken to ensure that the tool itself does not unduly affect the system under study. Here we report aberrant electrical activity, similar to interictal spikes, and accompanying fluorescence events in some genotypes of transgenic mice expressing GCaMP6 genetically-encoded calcium sensors. These epileptiform events have been observed particularly, but not exclusively, in mice with Emx1-Cre and Ai93 transgenes, across multiple laboratories. The events occur at >0.1 Hz, are very large in amplitude (>1.0 mV local field potentials, >10% df/f widefield imaging signals), and typically cover large regions of cortex. Many properties of neuronal responses and behavior seem normal despite these events, though rare subjects exhibit overt generalized seizures. The underlying mechanisms of this phenomenon remain unclear, but we speculate about possible causes on the basis of diverse observations. We encourage researchers to be aware of these activity patterns while interpreting neuronal recordings from affected mouse lines and when considering which lines to study
Graft Choice and the Incidence of Osteoarthritis After Anterior Cruciate Ligament Reconstruction: A Causal Analysis From a Cohort of 541 Patients
BACKGROUND: Anterior cruciate ligament (ACL) reconstruction is important to prevent knee osteoarthritis. Neither of the 2 most common graft techniques-the patellar tendon (PT) or hamstring tendon (HS) graft-has demonstrated superiority in terms of the long-term osteoarthritis rate.
HYPOTHESIS: Based on the International Knee Documentation Committee (IKDC) radiographic grading system, PT grafts decrease the incidence of osteoarthritis by providing better knee stability as compared with HS grafts over 12 years of follow-up.
STUDY DESIGN: Cohort study; Level of evidence, 3.
METHODS: All adults with a first ACL rupture who underwent surgery with a PT or HS graft technique between January 2002 and December 2003 were included in the 2014 French Society of Orthopedic Surgery and Traumatology Symposium database. Baseline characteristics were collected. The primary endpoint was the occurrence of moderate to severe osteoarthritis in each group. The secondary endpoints included clinical subjective evaluations by the IKDC score and Knee injury and Osteoarthritis Outcome Score. To control the differences in baseline characteristics, the data were analyzed with propensity score matching.
RESULTS: In the cohort, 541 patients from 18 centers were included: 311 PT and 230 HS ACL reconstructions. The baseline characteristics were similar after inverse probability weighting treatment (IPWT). The occurrence of osteoarthritis was similar after IPWT (19.3% for PT and 19.6% for HS, P = .94). Age at surgery >29 years and IKDC osteoarthritis stage B at the index surgery were identified as risk factors for moderate to severe osteoarthritis. Most functional outcomes were significantly higher in the HS group; however, the difference between groups remained <10 points. Of the 106 patients who needed a medial meniscectomy, the proportion of patients with moderate to severe osteoarthritis was much higher in the HS group (43.5% vs 18.3%, P = .006). However, after IPWT, the difference was not statistically significant.
CONCLUSION: At 12 years of follow-up, neither graft technique was superior to the other in terms of the rate of osteoarthritis
Mission N.M.A./PRIFAS d´etude et de prospective dans le Nordeste Bresilien: 7 au 23 juillet 1990.
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Widespread presence of direction-reversing neurons in the mouse visual system
Direction selectivity, the preference of motion in one direction over the opposite, is a fundamental property of visual neurons across species. We find that a substantial proportion of direction selective neurons in the mouse visual system reverse their preferred direction of motion in response to drifting gratings at different spatiotemporal parameters. A spatiotemporally asymmetric filter model recapitulates our experimental observations
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