The role of turbulence in star formation laws and thresholds

The Schmidt-Kennicutt relation links the surface densities of gas to the star formation rate in galaxies. The physical origin of this relation, and in particular its break, i.e. the transition between an inefficient regime at low gas surface densities and a main regime at higher densities, remains debated. Here, we study the physical origin of the star formation relations and breaks in several low-redshift galaxies, from dwarf irregulars to massive spirals. We use numerical simulations representative of the Milky Way, the Large and the Small Magellanic Clouds with parsec up to subparsec resolution, and which reproduce the observed star formation relations and the relative variations of the star formation thresholds. We analyze the role of interstellar turbulence, gas cooling, and geometry in drawing these relations, at 100 pc scale. We suggest in particular that the existence of a break in the Schmidt- Kennicutt relation could be linked to the transition from subsonic to supersonic turbulence and is independent of self-shielding effects. This transition being connected to the gas thermal properties and thus to the metallicity, the break is shifted toward high surface densities in metal-poor galaxies, as observed in dwarf galaxies. Our results suggest that together with the collapse of clouds under self-gravity, turbulence (injected at galactic scale) can induce the compression of gas and regulate star formation.Comment: 15 pages, 19 figures; accepted for publication in the Astrophysical Journa

Development and characterization of a new set of 164 polymorphic EST-SSR markers for diversity and breeding studies in rubber tree (Hevea brasiliensis Mull. Arg.)

Plant Breed.ISI Document Delivery No.: AJ4WPTimes Cited: 0Cited Reference Count: 31Cited References: Argout X, 2008, BMC GENOMICS, V9, DOI 10.1186/1471-2164-9-512 BESSE P, 1994, THEOR APPL GENET, V88, P199, DOI 10.1007/BF00225898 Conesa A, 2005, BIOINFORMATICS, V21, P3674, DOI 10.1093/bioinformatics/bti610 Cubry P, 2013, BMC GENOMICS, V14, DOI 10.1186/1471-2164-14-10 Ellis JR, 2007, HEREDITY, V99, P125, DOI 10.1038/sj.hdy.6801001 Feng SP, 2009, MOL BREEDING, V23, P85, DOI 10.1007/s11032-008-9216-0 Garcia D, 2011, PHYSIOL MOL PLANT P, V76, P126, DOI 10.1016/j.pmpp.2011.07.006 Gupta PK, 2005, PLANT MOL BIOL, V57, P461, DOI 10.1007/s11103-005-0257-z Gupta S, 2013, PLANT BREEDING, V132, P367, DOI 10.1111/pbr.12070 Kumar Yadav H., 2010, TREE GENET GENOMES, V7, P207 Le Guen V., 2008, EXPLORATION DIVERSIT Le Guen V, 2011, PLANT BREEDING, V130, P294, DOI 10.1111/j.1439-0523.2010.01774.x Le Guen V, 2009, TREE GENET GENOMES, V5, P673, DOI 10.1007/s11295-009-0218-9 Lespinasse D, 2000, THEOR APPL GENET, V100, P127, DOI 10.1007/s001220050018 Li DJ, 2012, BMC GENOMICS, V13, DOI 10.1186/1471-2164-13-192 Liu KJ, 2005, BIOINFORMATICS, V21, P2128, DOI 10.1093/bioinformatics/bti282 Ohyama A, 2009, MOL BREEDING, V23, P685, DOI 10.1007/s11032-009-9265-z Perovic D, 2009, MOL BREEDING, V23, P641, DOI 10.1007/s11032-009-9262-2 Perrier Xavier, 2003, P31 Perrier X., 2006, DARWIN SOFTWARE Pootakham W, 2012, PLANT BREEDING, V131, P555, DOI 10.1111/j.1439-0523.2012.01982.x Rafalski JA, 2010, CURR OPIN PLANT BIOL, V13, P174, DOI 10.1016/j.pbi.2009.12.004 Rozen S, 2000, Methods Mol Biol, V132, P365 SAITOU N, 1987, MOL BIOL EVOL, V4, P406 Seguin Marc, 2003, P277 Souza LM, 2009, CONSERV GENET RESOUR, V1, P75, DOI 10.1007/s12686-009-9018-7 Triwitayakorn K, 2011, DNA RES, V18, P471, DOI 10.1093/dnares/dsr034 Tyrka M, 2008, J APPL GENET, V49, P127, DOI 10.1007/BF03195605 Varshney RK, 2005, TRENDS BIOTECHNOL, V23, P48, DOI 10.1016/j.tibtech.2004.11.005 Vigouroux Y, 2005, GENETICS, V169, P1617, DOI 10.1534/genetics.104.032086 Wen Mingfu, 2010, BMC Res Notes, V3, P42, DOI 10.1186/1756-0500-3-42Cubry, Philippe Pujade-Renaud, Valerie Garcia, Dominique Espeout, Sandra Le Guen, Vincent Granet, Francoise Seguin, MarcFrench National Research Agency (Agence Nationale pour la Recherche; contrat ANR/Genoplante) [GPLA07017C]This work was performed as part of the CIRAD - Michelin collaborative project 'Genesalb' supported by a grant from the French National Research Agency (Agence Nationale pour la Recherche; contrat ANR/Genoplante no GPLA07017C). We thank the Montpellier Languedoc-Roussillon Grand plateau technique regional for hosting the SSR genotyping activities. ESTtik database was made available by the SouthGreen bioinformatics platform at http://southgreen.cirad.fr/. We thank Ronan Rivallan for technical help, Xavier Argout for computational procedures and data retrieving, Gerald Oliver for keeping some vegetal material in a greenhouse in Montpellier, Jean-Marc Thevenin and Fabien Doare for providing us with some fresh material from CIRAD's Pointe Combi Centre (French Guyana) collection.Wiley-blackwellHobokenDespite its economic importance and recent genome release, the need for molecular tools for Hevea brasiliensis is high. In the frame of a disease resistance study, EST sequences were retrieved from public database or generated by sequencing SSH libraries. Sequences were trimmed and microsatellite motifs searched using an ad hoc bioinformatic pipeline, and pairs of primers for the amplification of candidate markers were generated. We found a total of 10499 unigenes from both sources of sequences, and 673 microsatellites motifs were detected using the default parameters of the pipeline. Two hundred sixty-four primer pairs were tested and 226 (85.6%) successfully amplified. Out of the amplified candidate markers, 164 exhibited polymorphism. Relationships based on dendrograms using simple matching index and diversity statistics based on EST-SSRs were compared with Genomic SSRs, showing the potentialities of EST-derived microsatellites for resistance studies but also for population genetics approaches

Timing of antiretroviral therapy and adverse pregnancy outcomes : a systematic review and meta-analysis

BACKGROUND: Although life-long combination antiretroviral therapy (ART) is recommended for all HIV-infected individuals, there are limited data on pregnancy outcome with ART initiation pre-conception. We assessed the safety of ART initiated pre-conception versus post-conception on adverse pregnancy outcome. METHODS: We conducted a systematic review of studies from low-, middle-, and high-income countries. We searched Cochrane Central Register of Controlled Trials, EMBASE, LILACS, MEDLINE for randomized trials, quasi-randomized trials and prospective cohort studies conducted between 01 January 1980 to 01 June 2016). Risk ratios were pooled using a random-effects model. FINDINGS: Eleven studies were included (N=19,189 mother-infant pairs). Women initiating ART pre-conception compared to post-conception were significantly more likely to deliver preterm (pooled risk ratio[RR]=1·20, 95% confidence interval[CI] 1·01-1·14, 10 studies), very preterm (RR=1·53, 95%CI 1·22-1·92, two studies), or have low birth weight (LBW) infants (RR=1·30, 95%CI 1·04-1·62, two studies). Data on neonatal mortality was limited. We found no increase in very LBW (RR=0.18, 95% CI 0.02-1.51, one study), small for gestational age (SGA) (RR = 1·13, 95% CI 0·94-1·35, two studies), severe SGA (RR=1·09, 95%CI 0·82-1·45, one study), stillbirth (RR= RR=1·30, 95% CI 0·99-1·69, two studies) or congenital anomalies (RR= RR=1·24, 95% CI 0·61-2·49, one study). INTERPRETATION: The benefits of ART for maternal health and prevention of perinatal transmission outweigh risks, but there remain limited, poor quality data on the extent/severity of these risks. We found elevated preterm delivery and low birth weight rates associated with pre-conception ART. As pre-conception ART rapidly increases globally, it will be critical to monitor for potential adverse pregnancy outcomes

Polychromatic guide star: feasibility study

International audienceAdaptive optics at astronomical telescopes aims at correcting in real time the phase corrugations of incoming wavefronts caused by the turbulent atmosphere, as early proposed by Babcock. Measuring the phase errors requires a bright source located within the isoplanatic patch of the program source. The probability that such a reference source exists is a function of the wavelength, of the required image quality (Strehl ratio), of the turbulence optical properties, and of the direction of the observation. It turns out that the sky coverage is disastrously low in particular in the visible wavelength range where, unfortunately, the gain in spatial resolution brought by adaptive optics is the largest. Foy and Labeyrie have proposed to overcome this difficulty by creating an artificial point source in the sky in the direction of the observation relying on the backscattered light due to a laser beam. This laser guide star (hereinafter referred to as LGS) can be bright enough to allow us to accurately measure the wavefront phase errors, except for two modes which are the piston (not relevant in this case) and the tilt. Pilkington has emphasized that the round trip time of the laser beam to the mesosphere, where the LGS is most often formed, is significantly shorter than the typical tilt coherence time; then the inverse-return-of-light principle causes deflections of the outgoing and the ingoing beams to cancel. The apparent direction of the LGS is independent of the tilt. Therefore the tilt cannot be measured only from the LGS. Until now, the way to overcome this difficulty has been to use a natural guide star to sense the tilt. Although the tilt is sensed through the entire telescope pupil, one cannot use a faint source because $APEX 90% of the variance of the phase error is in the tilt. Therefore, correcting the tilt requires a higher accuracy of the measurements than for higher orders of the wavefront. Hence current adaptive optics devices coupled with a LGS face low sky coverage. Several methods have been proposed to get a partial sky coverage for the tilt. The only one providing us with a full sky coverage is the polychromatic LGS (hereafter referred to as PLGS). We present here a progress report of the R&D; program Etoile Laser Polychromatique et Optique Adaptative (ELP-OA) carried out in France to develop the PLGS concept. After a short recall of the principles of the PLGS, we will review the goal of ELP-OA and the steps to get over to bring it into play. We finally shortly described the effort in Europe to develop the LGS

Polychromatic guide star: feasibility study

International audienceAdaptive optics at astronomical telescopes aims at correcting in real time the phase corrugations of incoming wavefronts caused by the turbulent atmosphere, as early proposed by Babcock. Measuring the phase errors requires a bright source located within the isoplanatic patch of the program source. The probability that such a reference source exists is a function of the wavelength, of the required image quality (Strehl ratio), of the turbulence optical properties, and of the direction of the observation. It turns out that the sky coverage is disastrously low in particular in the visible wavelength range where, unfortunately, the gain in spatial resolution brought by adaptive optics is the largest. Foy and Labeyrie have proposed to overcome this difficulty by creating an artificial point source in the sky in the direction of the observation relying on the backscattered light due to a laser beam. This laser guide star (hereinafter referred to as LGS) can be bright enough to allow us to accurately measure the wavefront phase errors, except for two modes which are the piston (not relevant in this case) and the tilt. Pilkington has emphasized that the round trip time of the laser beam to the mesosphere, where the LGS is most often formed, is significantly shorter than the typical tilt coherence time; then the inverse-return-of-light principle causes deflections of the outgoing and the ingoing beams to cancel. The apparent direction of the LGS is independent of the tilt. Therefore the tilt cannot be measured only from the LGS. Until now, the way to overcome this difficulty has been to use a natural guide star to sense the tilt. Although the tilt is sensed through the entire telescope pupil, one cannot use a faint source because $APEX 90% of the variance of the phase error is in the tilt. Therefore, correcting the tilt requires a higher accuracy of the measurements than for higher orders of the wavefront. Hence current adaptive optics devices coupled with a LGS face low sky coverage. Several methods have been proposed to get a partial sky coverage for the tilt. The only one providing us with a full sky coverage is the polychromatic LGS (hereafter referred to as PLGS). We present here a progress report of the R&D; program Etoile Laser Polychromatique et Optique Adaptative (ELP-OA) carried out in France to develop the PLGS concept. After a short recall of the principles of the PLGS, we will review the goal of ELP-OA and the steps to get over to bring it into play. We finally shortly described the effort in Europe to develop the LGS

Efficacy of topical versus intravenous tranexamic acid in spinal deformity

Purpose To compare topical tranexamic acid versus intravenous tranexamic acid in reducing intra- and postoperative blood loss and transfusion rate in deformity patients. Materials and method We performed a retrospective cohort study with posterior fusion deformity patients, between 2009 and 2016. Patients were categorized in 4 groups: "No TXA" (n = 35) if the wound was packed with saline soaked sponges, "IV TXA" (n = 37) the patient received 20 mg/kg bolus at the beginning of the surgery followed by continuous infusion of 1 mg/kg/hr until closure, "Topical TXA" (n = 23) the wound was packed with sponges soaked in 6 g of TXA diluted in a 3 L saline solution, or "Combined TXA" (n = 86) the patient received both IV and topical TXA. The primary outcomes were total, intra- and postoperative blood loss, surgical time, postoperative Ht/Hb, transfusion rates, and duration of drain insertion. Results A total of 181 patients were analyzed (78.6%F, 15.08 yo). No differences were found in total and intraoperative blood loss, surgical time, postoperative Ht/Ht, and transfusion rates. "Combined TXA" group had significantly less postoperative bleeding than "no TXA" group (p = 0.022). IV TXA patients (with o/without topical TXA) removed drains one day earlier than the no TXA group (p = 0.002). There were no complications related to the use of tranexamic acid. Conclusion There is significant decrease in postoperative bleeding in pediatric deformity patients with combined topical and IV tranexamic acid

Heterogeneity of Environments Associated with Transmission of Visceral Leishmaniasis in South-Eastern France and Implication for Control Strategies

International audienceBackground: Visceral leishmaniasis due to Leishmania infantum is currently spreading into new foci across Europe. Leishmania infantum transmission in the Old World was reported to be strongly associated with a few specific environments. Environmental changes due to global warming or human activity were therefore incriminated in the spread of the disease. However, comprehensive studies were lacking to reliably identify all the environments at risk and thereby optimize monitoring and control strategy. Methodology/Findings: We exhaustively collected 328 cases of autochthonous visceral leishmaniasis from 1993 to 2009 in SouthEastern France. Leishmaniasis incidence decreased from 31 yearly cases between 1993 and 1997 to 12 yearly cases between 2005 and 2009 mostly because Leishmania/HIV coinfection were less frequent. No spread of human visceral leishmaniasis was observed in the studied region. Two major foci were identified, associated with opposite environments: whereas one involved semi-rural hillside environments partly made of mixed forests, the other involved urban and peri-urban areas in and around the region main town, Marseille. The two neighboring foci were related to differing environments despite similar vectors (P. perniciosus), canine reservoir, parasite (L. infantum zymodeme MON-1), and human host. Conclusions/Significance: This unprecedented collection of cases highlighted the occurrence of protracted urban transmission of L. infantum in France, a worrisome finding as the disease is currently spreading in other areas around the Mediterranean. These results complete previous studies about more widespread canine leishmaniasis or human asymptomatic carriage. This first application of systematic geostatistical methods to European human visceral leishmaniasis demonstrated an unsuspected heterogeneity of environments associated with the transmission of the disease. These findings modify the current view of leishmaniasis epidemiology. They notably stress the need for locally defined control strategies and extensive monitoring including in urban environments

Quantitative Investigation of Bone Microvascularization from 3D Synchrotron Micro-Computed Tomography in a Rat Model

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Direct Non-Invasive Measuring Techniques ofNanometric Liquid Level Variations UsingExtrinsic Fiber Fabry–Perot Interferometers

International audienceThis article investigates two different non-contact non-invasive solutions for measuring nanometric-order liquid-surface displacements with Extrinsic FiberFabry-Perot interferometers. They are investigated fordeveloping hydrostatic leveling sensor (HLS) systemstargeting the detection of very slowly-evolving movementsin geophysics and geotechnics. In the first technique,the sensing beam from the interferometer traverses a liquidof known refractive index and is reflected by a mirrorsubmerged at the bottom of the HLS vessel. The liquid-levelvariation is thus sensed as a variation of the optical pathlength of the interrogating beam. The second solution, on theother hand, directly exploits the reflection of the sensingbeam at the air-liquid interface in the absence of a reflective surface in the vessel. The subsequent variation of liquid levelis then measured directly as the beam’s optical path variation in air. The common denominator of these two techniquesis an Extrinsic Fabry-Perot sensor with nanometric precision operating at a wavelength of∼1310 nm. The interrogatingbeam suffers from high IR absorption in water, hence the latter solution is more advantageous in terms of dynamicrange. In applications where liquids other than water canbe employed, the use of low optical absorption liquids suchas Polydimethylsiloxanic fluids is recommended at this operating wavelength. Being more viscous and less volatile thanwater, these fluids can significantly improve the noise floor of HLS systems, hence contributing to a larger dynamicrange, lower instrumental drift and higher signal-to-noise ratio