983 research outputs found
Obliteration study of lambdatic and obelionic region sutures in ruminant, carnivores and hominids
The morphology of Orce cranial fragment VM-0 is contrasted with the fronto-parietal region in artiodactyls, and the obelionic region in carnivores and primates including hominids. Sutural development at obelion is compared in those taxa throughout the growth period up to the onset of sutural obliteration, and ontogenetic differences between non-primates and primates lead us to conclude that the configuration in VM-0 more resembles that found in hominids than in artiodactyls or carnivores. Moreover, cranial capacity for VM-0 is estimated at >470cm3, comparable to Plio Pleistocene hominids, but greater than in young equids.La morfología del fragmento cranial de Orce (VM-0) se contrasta con la región fronto-parietal de los artiodáctilos y con la región obélica de los carnívoros y primates incluyendo los homínidos. Se compara en estos taxones, el desarrollo de las suturas en esta región a lo largo del periodo de crecimiento hasta que ocurre la obliteración de las mismas. Las diferencias ontogenéticas entre no primates y primates nos permiten concluir que la anatomía de VM-0 es más próxima a los hominidos que a la de los artiodáctilos y carnívoros. Se estima que la capacidad craneana de VM-0 tiene que ser > 470 cm3, comparable a la de los homínidos del Plio-Pleistoceno y mayor que la de los équidos juveniles
River inflow and salinity changes in the Caspian Sea during the last 5500 years
Pollen, spores and dinoflagellate cysts have been analysed on three sediment cores (1.8–1.4 m-long) taken from the south and middle basins of the Caspian Sea. A chronology available for one of the cores is based on calibrated radiocarbon dates (ca 5.5–0.8 cal. ka BP). The pollen and spores assemblages indicate fluctuations between steppe and desert. In addition there are some outstanding zones with a bias introduced by strong river inflow. The dinocyst assemblages change between slightly brackish (abundance of Pyxidinopsis psilata and Spiniferites cruciformis) and more brackish (dominance of Impagidinium caspienense) conditions. During the second part of the Holocene, important flow modifications of the Uzboy River and the Volga River as well as salinity changes of the Caspian Sea, causing sea-level fluctuations, have been reconstructed. A major change is suggested at ca 4 cal. ka BP with the end of a high level phase in the south basin. Amongst other hypotheses, this could be caused by the end of a late and abundant flow of the Uzboy River (now defunct), carrying to the Caspian Sea either meltwater from higher latitudes or water from the Amu-Daria. A similar, later clear phase of water inflow has also been observed from 2.1 to 1.7 cal. ka BP in the south basin and probably also in the north of the middle basin
Flexible compiler-managed L0 buffers for clustered VLIW processors
Wire delays are a major concern for current and forthcoming processors. One approach to attack this problem is to divide the processor into semi-independent units referred to as clusters. A cluster usually consists of a local register file and a subset of the functional units, while the data cache remains centralized. However, as technology evolves, the latency of such a centralized cache increase leading to an important performance impact. In this paper, we propose to include flexible low-latency buffers in each cluster in order to reduce the performance impact of higher cache latencies. The reduced number of entries in each buffer permits the design of flexible ways to map data from L1 to these buffers. The proposed L0 buffers are managed by the compiler, which is responsible to decide which memory instructions make us of them. Effective instruction scheduling techniques are proposed to generate code that exploits these buffers. Results for the Mediabench benchmark suite show that the performance of a clustered VLIW processor with a unified L1 data cache is improved by 16% when such buffers are used. In addition, the proposed architecture also shows significant advantages over both MultiVLIW processors and clustered processors with a word-interleaved cache, two state-of-the-art designs with a distributed L1 data cache.Peer ReviewedPostprint (published version
Subtraction of temperature induced phase noise in the LISA frequency band
Temperature fluctuations are expected to be one of the limiting factors for
gravitational wave detectors in the very low frequency range. Here we report
the characterisation of this noise source in the LISA Pathfinder optical bench
and propose a method to remove its contribution from the data. Our results show
that temperature fluctuations are indeed limiting our measurement below one
millihertz, and that their subtraction leads to a factor 5.6 (15 dB) reduction
in the noise level at the lower end of the LISA measurement band 10^{-4} Hz,
which increases to 20.2 (26 dB) at even lower frequencies, i.e., 1.5x10^{-5}
Hz. The method presented here can be applied to the subtraction of other noise
sources in gravitational wave detectors in the general situation where multiple
sensors are used to characterise the noise source.Comment: 8 pages, 6 figure
Lagrangian temperature, velocity and local heat flux measurement in Rayleigh-Benard convection
We have developed a small, neutrally buoyant, wireless temperature sensor.
Using a camera for optical tracking, we obtain simultaneous measurements of
position and temperature of the sensor as it is carried along by the flow in
Rayleigh-B\'enard convection, at . We report on statistics of
temperature, velocity, and heat transport in turbulent thermal convection. The
motion of the sensor particle exhibits dynamics close to that of Lagrangian
tracers in hydrodynamic turbulence. We also quantify heat transport in plumes,
revealing self-similarity and extreme variations from plume to plume.Comment: 4 page
Muons tomography applied to geosciences and volcanology
Imaging the inner part of large geological targets is an important issue in
geosciences with various applications. Dif- ferent approaches already exist
(e.g. gravimetry, electrical tomography) that give access to a wide range of
informations but with identified limitations or drawbacks (e.g. intrinsic
ambiguity of the inverse problem, time consuming deployment of sensors over
large distances). Here we present an alternative and complementary tomography
method based on the measurement of the cosmic muons flux attenuation through
the geological structures. We detail the basics of this muon tomography with a
special emphasis on the photo-active detectors.Comment: Invited talk at the 6th conference on New Developments In
Photodetection (NDIP'11), Lyon-France, July 4-8, 2011; Nuclear Instruments
and Methods in Physics Research Section A, 201
Filtering non-stationary geophysical data with orthogonal wavelets
WOS:A1996TW55100023International audienceA filtering method based on both orthogonal wavelet decomposition and chi-squared statistics is proposed to clean non-stationary signals embedded in a gaussian white noise. An application to a time series of thermistance data recorded in an underground quarry illustrates the interest of the technique
Towards a FPGA-controlled deep phase modulation interferometer
Deep phase modulation interferometry was proposed as a method to enhance
homodyne interferometers to work over many fringes. In this scheme, a
sinusoidal phase modulation is applied in one arm while the demodulation takes
place as a post-processing step. In this contribution we report on the
development to implement this scheme in a fiber coupled interferometer
controlled by means of a FPGA, which includes a LEON3 soft-core processor. The
latter acts as a CPU and executes a custom made application to communicate with
a host PC. In contrast to usual FPGA-based designs, this implementation allows
a real-time fine tuning of the parameters involved in the setup, from the
control to the post-processing parameters.Comment: Proceedings of the X LISA Symposium, Gainesville, May 18-23, 201
On the Slow Drift of Solstices: Milankovic Cycles and Mean Global Temperature
The Earth's revolution is modified by changes in inclination of its rotation
axis. Despite the fact that the gravity field is central, the Earth's
trajectory is not closed and the equinoxes drift. Milankovic (1920) argued that
the shortest precession period of solstices is 20,7kyr: the Summer solstice in
one hemisphere takes place alternately every 11kyr at perihelion and at
aphelion. We have submitted the time series for the Earth's pole of rotation,
global mean surface temperature and ephemeris to iterative Singular Spectrum
Analysis. iSSA extracts from each a trend, a 1yr and a 60yr component. Both the
apparent drift of solstices of Earth around the Sun and the global mean
temperature exhibit a strong 60yr oscillation. The "fixed dates" of solstices
actually drift. Comparing the time evolution of the Winter and Summer solstices
positions of the rotation pole and the first iSSA component (trend) of the
temperature allows one to recognize some common features. A basic equation from
Milankovic links the derivative of heat received at a given location on Earth
to solar insolation, known functions of the location coordinates, solar
declination and hour angle, with an inverse square dependence on the Sun-Earth
distance. We have translated the drift of solstices as a function of distance
to the Sun into the geometrical insolation theory of Milankovic. Shifting the
inverse square of the 60yr iSSA drift of solstices by 15 years with respect to
the first derivative of the 60yr iSSA trend of temperature, that is exactly a
quadrature in time, puts the two curves in quasi-exact superimposition. The
probability of a chance coincidence appears very low. Correlation does not
imply causality when there is no accompanying model. Here Milankovic's equation
can be considered as a model that is widely accepted. This paper identifies a
case of agreement between observations and a mathematical formulation
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