2,952 research outputs found
Modelling study of transformations of the exchange flows along the Strait of Gibraltar
Abstract. Vertical transfers of heat, salt and mass between the inflowing
and outflowing layers at the Strait of Gibraltar are explored basing on the outputs of a
three-dimensional fully nonlinear numerical model. The model covers the entire
Mediterranean basin and has a very high spatial resolution around the strait
(1/200∘). Another distinctive feature of the model is that it includes a
realistic barotropic tidal forcing (diurnal and semi-diurnal), in addition to atmospheric
pressure and heat and water surface fluxes. The results show a significant transformation
of the properties of the inflowing and outflowing water masses along their path through
the strait. This transformation is mainly induced by the recirculation of water, and
therefore of heat and salt, between the inflowing and outflowing layers. The underlying
process seems to be the hydraulic control acting at the Espartel section, Camarinal Sill
and Tarifa Narrows, which limits the amount of water that can cross the sections and
forces a vertical recirculation. This results in a complex spatio-temporal pattern of
vertical transfers, with the sign of the net vertical transfer being opposite in each
side of the Camarinal Sill. Conversely, the mixing seems to have little influence on the heat
and salt exchanged between layers (∼2 %–10 % of advected heat and salt).
Therefore, the main point of our work is that most of the transformation of water
properties along the strait is induced by the vertical advection of heat and salt and not
by vertical mixing. A simple relationship between the net flux and the vertical transfers
of water, heat and salt is also proposed. This relationship could be used for the fine-tuning of coarse-resolution model parameterizations in the strait
Brief of Law Professors as Amicus Curiae in Support of Respondent
Inventors lacking assurance of a market, or even the right to practice patented inventions, face considerable risk. Those who qualify for patents, in return for disclosure, receive only the assistance of the courts in excluding others from economic exploitation of their inventions. Already subject to many legislative and judicial limitations, patents should not be further subject to the functional equivalent of private inverse condemnation without congressional action
CHARACTERIZATION OF THE 105 K SUPERCONDUCTOR Tl2Ba2CaCu208 ("2212")
International audienceHomogeneous Tl1.8Ba2CaCu208 ceramics were synthesized by a novel route, starting from Tl2Ba205 precursors and using high gas pressures. This method allows tight control of thallium losses, resulting in dense, large-grained samples with sharp superconducting transitions above 105 K. Results of a characterization by X-ray diffraction, optical micrographs and micro-probe analysis are presented, together with selected physical properties
Recommended from our members
Characterization of the Subsurface of 67P/Churyumov-Gerasimenko's Abydos Site
We investigate the structure of the subsurface of the Abydos site using a cometary nucleus model with parameters adapted to comet 67P/Churyumov-Gerasimenko and the Abydos landing site. We aim to compare the production rates derived from our model with those of the main molecules measured by Ptolemy. This will allow us to retrieve the depths at which the different molecules still exist in solid form
Recommended from our members
Spatial and temporal variations of the seasonal sea level cycle in the northwest Pacific
The seasonal sea level variations observed from tide gauges over 1900-2013 and gridded satellite altimeter product AVISO over 1993-2013 in the northwest Pacific have been explored. The seasonal cycle is able to explain 60-90% of monthly sea level variance in the marginal seas, while it explains less than 20% of variance in the eddy-rich regions. The maximum annual and semi-annual sea level cycles (30cm and 6cm) are observed in the north of the East China Sea and the west of the South China Sea respectively. AVISO was found to underestimate the annual amplitude by 25% compared to tide gauge estimates along the coasts of China and Russia.
The forcing for the seasonal sea level cycle was identified. The atmospheric pressure and the steric height produce 8-12cm of the annual cycle in the middle continental shelf and in the Kuroshio Current regions separately. The removal of the two attributors from total sea level permits to identify the sea level residuals that still show significant seasonality in the marginal seas. Both nearby wind stress and surface currents can explain well the long-term variability of the seasonal sea level cycle in the marginal seas and the tropics because of their influence on the sea level residuals. Interestingly, the surface currents are a better descriptor in the areas where the ocean currents are known to be strong. Here, they explain 50-90% of inter-annual variability due to the strong links between the steric height and the large-scale ocean currents
Flights in my hands : coherence concerns in designing Strip'TIC, a tangible space for air traffic controllers
Best Paper Honorable Mention awardInternational audienceWe reflect upon the design of a paper-based tangible interactive space to support air traffic control. We have observed, studied, prototyped and discussed with controllers a new mixed interaction system based on Anoto, video projection, and tracking. Starting from the understanding of the benefits of tangible paper strips, our goal is to study how mixed physical and virtual augmented data can support the controllers' mental work. The context of the activity led us to depart from models that are proposed in tangible interfaces research where coherence is based on how physical objects are representative of virtual objects. We propose a new account of coherence in a mixed interaction system that integrates externalization mechanisms. We found that physical objects play two roles: they act both as representation of mental objects and as tangible artifacts for interacting with augmented features. We observed that virtual objects represent physical ones, and not the reverse, and, being virtual representations of physical objects, should seamlessly converge with the cognitive role of the physical object. Finally, we show how coherence is achieved by providing a seamless interactive space
Angular Correlations in Internal Pair Conversion of Aligned Heavy Nuclei
We calculate the spatial correlation of electrons and positrons emitted by
internal pair conversion of Coulomb excited nuclei in heavy ion collisions. The
alignment or polarization of the nucleus results in an anisotropic emission of
the electron-positron pairs which is closely related to the anisotropic
emission of -rays. However, the angular correlation in the case of
internal pair conversion exhibits diverse patterns. This might be relevant when
investigating atomic processes in heavy-ion collisions performed at the Coulomb
barrier.Comment: 27 pages + 6 eps figures, uses revtex.sty and epsf.sty,
tar-compressed and uuencoded with uufile
Radiocarbon dating casts doubt on the late chronology of the Middle to Upper Palaeolithic transition in southern Iberia
It is commonly accepted that some of the latest dates for Neanderthal fossils and Mousterian industries are found south of the Ebro valley in Iberia at ca. 36 ka calBP (calibrated radiocarbon date ranges). In contrast, to the north of the valley the Mousterian disappears shortly before the Proto-Aurignacian appears at ca. 42 ka calBP. The latter is most likely produced by anatomically modern humans. However, two-thirds of dates from the south are radiocarbon dates, a technique that is particularly sensitive to carbon contaminants of a younger age that can be difficult to remove using routine pretreatment protocols. We have attempted to test the reliability of chronologies of 11 southern Iberian Middle and early Upper Paleolithic sites. Only two, Jarama VI and Zafarraya, were found to contain material that could be reliably dated. In both sites, Middle Paleolithic contexts were previously dated by radiocarbon to less than 42 ka calBP. Using ultrafiltration to purify faunal bone collagen before radiocarbon dating, we obtain ages at least 10 ka 14C years older, close to or beyond the limit of the radiocarbonmethod for the Mousterian at Jarama VI and Neanderthal fossils at Zafarraya. Unless rigorous pretreatment protocols have been used, radiocarbon dates should be assumed to be inaccurate until proven otherwise in this region. Evidence for the late survival of Neanderthals in southern Iberia is limited to one possible site, Cueva Antón, and alternative models of human occupation of the region should be considered
Interferometric imaging of the sulfur-bearing molecules H2S, SO and CS in comet C/1995 O1 (Hale-Bopp)
We present observations of rotational lines of H2S, SO and CS performed in
comet C/1995 O1 (Hale-Bopp) in March 1997 with the Plateau de Bure
interferometer (IRAM). The observations provide informations on the spatial and
velocity distributions of these molecules. They can be used to constrain their
photodissociation rate and their origin. We use a radiative transfer code which
allows us to compute synthetic line profiles and interferometric maps, to be
compared to the observations. Both single-dish spectra and interferometric
spectral maps show a day/night asymmetry in the outgassing. From the analysis
of the spectral maps, including the astrometry, we show that SO and CS present
in addition a jet-like structure that may be the gaseous counterpart of the
dust high-latitude jet observed in optical images. A CS rotating jet is also
observed. Using the astrometry provided by continuum radio maps obtained in
parallel, we conclude that there is no need to invoke of nongravitational
forces acting on this comet, and provide an updated orbit. The radial extension
of H2S is found to be consistent with direct release from the nucleus. SO
displays an extended radial distribution. Assuming that SO2 is the parent of
SO, the photodissociation rate of SO is measured to be 1.5 E-4 s-1 at 1 AU from
the Sun. This is lower than most laboratory-based estimates and may suggest
that SO is not solely produced by SO2 photolysis. From the observations of
J(2-1) and J(5-4) CS lines, we deduce a CS photodissociation rate of 1 to 5 E-5
s-1. The photodissociation rate of CS2, the likely parent of CS, cannot be
constrained due to insufficient resolution, but our data are consistent with
published values. These observations illustrate the cometary science that will
be performed with the future ALMA interferometer.Comment: Accepted for publication in Astronomy & Astrophysic
- …