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Constructional sedimentary history of coastal barriers can provide insights regarding meteorological and oceanographic processes, and relative sea-level changes. We investigated the Holocene evolution of a segment of the Rio Grande do Sul Coastal Plain in southernmost Brazil. Data were obtained from ground-penetrating radargrams, optically stimulated luminescence dating, altimetry measurements, Google Earth imagery, and aerial photographs. These data allowed a qualitative and quantitative analysis of the beach profiles recorded in the radargrams. From which eolian, backshore/foreshore, breaker bars, and upper and lower shoreface radar facies were identified. The beach-related radar facies are recorded in twenty-eight progradational sand units (sigmoidal bodies). These units record increments of relatively steady deposition bounded by erosional surfaces produced by anomalous, high-magnitude storm events taking place about every 250 years. The upper shoreface strata include two to three breaker bars. Several pieces of evidence (number of breaker bars, upper shoreface gradient and progradation rate) suggest an alternation between dissipative and intermediate stages of barrier morphodynamics and a decrease of wave energy from 2 ka onwards. The barrier prograded during the last 7.1 ka, and initially, barrier progradation occurred because of a normal regression during a relative sea-level rise followed by a stillstand. Later, barrier progradation took place as a forced regression driven by a relative sea-level fall.
The zoonotic cestode Echinococcus ortleppi (Lopez-Neyra and Soler Planas, 1943) is mainly transmitted between dogs and cattle. It occurs worldwide but is only found sporadically in most regions, with the notable exception of parts of southern Africa and South America. Its epidemiology is little understood and the extent of intraspecific variability is unknown. We have analysed in the present study the genetic diversity among 178 E. ortleppi isolates from sub-Saharan Africa, Europe and South America using the complete mitochondrial cox1 (1608 bp) and nad1 (894 bp) DNA sequences. Genetic polymorphism within the loci revealed 15 cox1 and six nad1 haplotypes, respectively, and 20 haplotypes of the concatenated genes. Presence of most haplotypes was correlated to geographical regions, and only one haplotype had a wider spread in both eastern and southern Africa. Intraspecific microvariance was low in comparison with Echinococcus granulosus sensu stricto, despite the wide geographic range of examined isolates. In addition, the various sub-populations showed only subtle deviation from neutrality and were mostly genetically differentiated. This is the first insight into the population genetics of the enigmatic cattle adapted Echinococcus ortleppi. It, therefore, provides baseline data for biogeographical comparison among E. ortleppi endemic regions and for tracing its translocation paths.
Up-conversion, or hybrid, detectors have been investigated in quantum communication experiments to replace Indium-Gallium-Arsenide avalanche photodiodes (InGaAs-APD) for the detection of infrared and telecom single photons. Those detectors are based on the supposedly noise-free process of frequency up-conversion, also called sum-frequency generation (SFG), using a second order (χ2) non-linear crystal. Powered by an intense pump laser, this process permits transposing with a certain probability the single photons at telecom wavelengths to the visible range where silicon APDs (Si-APD) operate with a much better performance than InGaAs detectors. To date, the literature reports up-conversion detectors having efficiency and noise figures comparable to that of the best commercially available IngaAs-APDs. However, in all of these previous realizations, a pump-induced noise is always observed which was initially expected to be as low as the dark count level of the Si-APDs. Although this additional noise represents a problem for the detection, up-conversion detectors have advantageously replaced InGaAs-APDs in various long-distance quantum cryptography schemes since they offer a continuous regime operation mode instead of a gated mode necessary for InGaAs-APDs, and the possibility of much higher counting rates. Despite attempted explanations, no detailed nor conclusive study of this noise has been reported.
The aim of this paper is to offer a definitive explanation for this noise.
We first give a review of the state of the art by describing already demonstrated up-conversion detectors. We discuss these realizations especially regarding the choices made for the material, in bulk or guided configurations, the single photon wavelengths, and the pump scheme. Then we describe an original device made of waveguides integrated on periodically poled lithium niobate (PPLN)or on single-domain lithium niobate aimed at investigating the origin of the additional pump-induced noise. The poled waveguides are designed to
up-convert single photons at 1550 nm to 600 nm when a 980 nm diode laser is used as pump. We obtain an overall efficiency of about 0.6% for a noise level of about 8 × 103 counts/s. This overall efficiency includes both insertion and propagation losses, and internal up-conversion and quantum detection (Si-APD) efficiencies. Despite a low efficiency value compared to what has been obtained so far by other groups, the efficiency/noise ratio is still comparable which still allows us investigating the noise issue.
From the spectrum obtained in both poled and non-poled waveguides we conclude that the noise comes from an alternative phase-matching scheme which permits creating paired photons at 1550 and 2700 nm wavelength by down-conversion of the 980 nm pump laser. Knowing that 1550 nm corresponds to the input signal wavelength, up-conversion of actual signal or pump-induced photons at this particular wavelength cannot be discriminated, therefore contributing to the noise at the final wavelength of 600 nm. We believe that this process of down-conversion of the pump laser to the signal wavelength (plus complementary wavelength) is responsible for the unexpected noise level reported in all the up-conversion detector realizations.
We present recent advances on ultra low noise visible detectors at Laboratoire d'Astrophysique de Marseille, photon counting and EMCCD developments in collaboration with Observatoire de haute provence, Laboratoire d'astrophysique de l'observatoire de Grenoble and Laboratoire d'Astrophysique Experimentale (Montreal). After a review of the progress with third generation Image Photon Counting Systems (IPCS), we present the OCAM camera, based on the E2V CCD220 EMCCD, part of the Opticon JRA2 programme, and the CCCP controller, a new controller for the 3DNTT instrument that reduces the clock induced charge of an EMCCD by a factor 10, making it competitive with IPCS detectors for very faint fluxes. We will finally present the RAPID project and the concept of photon counting avalanche photodiode CMOS device (in collaboration with CEA-LETI) which is foreseen to be the ultimate detector for the visible-IR range providing no readout noise, high QE and extremely fast readout.
ArTeMiS is a bolometer camera that will be installed at the APEX submillimeter telescope in Chile in 2010. This instrument will be a powerful tool for scientists with its three focal planes that will operate simultaneously in background limited conditions at 200, 350 and 450 microns (5760 pixels in total). A prototype called p-ArTeMiS has been tested at APEX in 2007 and thanks to its good performances, the team has been able to conduct scientific projects in star formation and on debris disks. This paper summarises the details of the ArTeMiS project, with a description of the detectors, the optics, the cryogenics and the electronics. We will also present the undergoing studies at CEA on detectors for the future submillimeter space missions.
This document is a recap of an oral presentation made at Nice during
the INSU Astrophysics Detector Workshop 2008. It aims at giving an
overview of the achievements and ongoing developments presently carried
out at CEA-LETI in the field of Infrared focal plane array. Although
most of the research actually performed at LETI is not driven by space
oriented application, the excellence and the cutting edge of the outcome
is or can be applied to space-dedicated components. This paper focus
on features and developments from which astrophysics observation would
benefit in the near future on the European market. This encompassed
“traditionnal” developments such as format enlargement, low dark current
technology such as p/n structure but it also shade light on promising
and thrilling development such as avalanche photodiode array. It eventually
gives some hints of none MCT technologies processed at LETI.
Background and objective: The combination of non-opioid analgesic drugs, though widely used, has been rarely evaluated. The aim of this study was to compare the efficacy of propacetamol and the non-steroidal analgesic drug ketoprofen, alone or in combination, on pain relief after thyroid surgery performed using remifentanil.
Methods: Ninety-seven patients were randomly allocated to one of the three groups: propacetamol 2 g (32), ketoprofen 100 mg (33) and propacetamol 2 g + ketoprofen 100 mg (32). Each regimen was administered intravenously (i.v.) 30 min before the end of surgery and then every 6 h. If pain was not relieved, patients received an i.v. bolus of tramadol 100 mg. Tramadol consumption and pain intensity using a visual analogue scale was recorded at 1, 2, 8 and 14 h after the end of surgery.
Results: Pain scores were significantly higher with propacetamol compared with ketoprofen 2 h after surgery (35 ± 3.7, 21 ± 2.6, respectively; P < 0.01). The number of patients receiving tramadol was higher with propacetamol alone compared with the two other groups, 1 h (14/32, 4/33, 2/32, respectively; P > 0.01) and 2 h (24/32, 6/33, 8/32, respectively; P < 0.01) after surgery. There was no difference between ketoprofen alone and ketoprofen plus propacetamol, and there was no difference between the three groups from the 8th hour onward.
Conclusions: In the immediate postoperative period after thyroid surgery performed using remifentanil, the concomitant use of propacetamol and ketoprofen does not improve analgesia compared with ketoprofen alone.