143 research outputs found
Les annonces de notations extrafinanciÚres véhiculent-elles une information au marché?
(VF)Cet article analyse comment les investisseurs rĂ©agissent aux annonces de notations sociĂ©tales. GrĂące Ă un Ă©chantillon dâannonces sur le marchĂ© français par Vigeo sur la pĂ©riode 2004-2009, nous mettons en Ă©vidence un impact globalement positif sur les rentabilitĂ©s, qui dĂ©pend de la valeur du score et du domaine de notation. Sur les Ă©changes, nous observons deux effets qui se compensent : une baisse des volumes de transaction avant, suivie d'une hausse aprĂšs l'annonce.(VA)This paper examines how investors react to announcements of corporate social responsibility. From a sample of corporate social rating announcements by Vigeo on the French stock market during the 2004-2009 period, we find a significantly positive effect on stock returns, which depends on the score value and the field of notation. We observe compensating effects on trading volume: a decrease before the announcement followed by an increase afterwards.notation sociĂ©tale;performance sociĂ©tale et financiĂšre;ISR.corporate social responsibility rating;social and financial performance;SRI.
Salicylic Acid, an Ambimobile Molecule Exhibiting a High Ability to Accumulate in the Phloem
International audienceThe ability of exogenous salicylic acid (SA) to accumulate in castor bean (Ricinus communis) phloem was evaluated by HPLC and liquid scintillation spectrometry analyses of phloem sap collected from the severed apical part of seedlings. Time-course experiments indicated that SA was transported to the root system via the phloem and redistributed upward in small amounts via the xylem. This helps to explain the peculiarities of SA distribution within the plant in response to biotic stress and exogenous SA application. Phloem loading of SA at 1, 10, or 100 mM was dependent on the pH of the cotyledon incubating solution, and accumulation in the phloem sap was the highest (about 10-fold) at the most acidic pH values tested (pH 4.6 and 5.0). As in animal cells, SA uptake still occurred at pH values close to neutrality (i.e. when SA is only in its dissociated form according to the calculations made by ACD LogD suite software). The analog 3,5-dichlorosalicylic acid, which is predicted to be nonmobile according to the models of Bromilow and Kleier, also moved in the sieve tubes. These discrepancies and other data may give rise to the hypothesis of a possible involvement of a pH-dependent carrier system translocating aromatic monocarboxylic acids in addition to the ion-trap mechanism
L'arsenal phytosanitaire face aux ennemis des plantes. Considérations générales
Les plantes sont attaquĂ©es, non seulement par divers types de micro-organismes pathogĂšnes, mais aussi par d'autres ennemis, parmi lesquels des mollusques, des nĂ©matodes, des acariens et des insectes. Elles peuvent dĂ©velopper des stratĂ©gies complexes et efficaces pour faire face aux pathogĂšnes (rĂ©action hypersensible et rĂ©sistance systĂ©mique acquise) et aux herbivores (Ă©missions de produits volatils attirant des parasites de l'agresseur, synthĂšse d'inhibiteurs de protĂ©inases). Cependant, la confrontation de la plante avec les agresseurs peut aussi tourner Ă l'avantage de ces derniers. Aussi, dans le passĂ©, l'attaque des cultures a-telle rĂ©guliĂšrement gĂ©nĂ©rĂ© des pertes Ă©conomiques considĂ©rables. Ă partir de la seconde guerre mondiale, l'essor de la chimie organique, associĂ© Ă la prise en considĂ©ration des problĂšmes du monde agricole, a dĂ©bouchĂ© sur la mise au point d'un nombre sans cesse croissant de produits phytosanitaires. Ils se rĂ©partissent actuellement en une dizaine de classes, les herbicides, les fongicides et les insecticidesâacaricides, reprĂ©sentant plus de 90% du marchĂ© mondial. La plupart des produits phytosanitaires mis sur le marchĂ© au cours de ces trois derniĂšres dĂ©cennies sont actifs Ă faible dose et bĂ©nĂ©ficient d'un profil toxicologique et cotoxicologique nettement plus favorable que celui des premiĂšres familles de pesticides, ces derniĂšres Ă©tant maintenant totalement ou partiellement retirĂ©es du marchĂ©. Plusieurs familles plus ou moins rĂ©centes sont des analogues de mĂ©tabolites produits par divers types d'organismes. Les progrĂšs rĂ©alisĂ©s dans la protection des cultures sont donc remarquables, mais les dĂ©sĂ©quilibres environnementaux crĂ©Ă©s ont gĂ©nĂ©rĂ© une dĂ©pendance vis-Ă -vis des phytosanitaires. Fort judicieusement, des stratĂ©gies alternatives (Ă©liciteurs, ingĂ©nierie gĂ©nĂ©tique par exemple) ont Ă©tĂ© initiĂ©es ou dĂ©veloppĂ©es lors de la derniĂšre dĂ©cennie
Salicylic Acid, an Ambimobile Molecule Exhibiting a High Ability to Accumulate in the Phloem
Unsaturated amino acids derived from isoleucine trigger early membrane effects on plant cells
International audienc
ED Referral Dramatically Reduces Delays of Initial Evaluation in a French TIA Clinic
Background: The risk of recurrent brain infarction (BI) is high within the first hours after a transient ischemic attack (TIA). Emergent, specialized, and tailored patient management in a TIA program reduces the risk of recurrent BI after TIA by 80%. New antithrombotic strategies have been successfully tested within 12 h after TIA onset. We aim to investigate the factors associated with a delay of more than 12 h from TIA onset to evaluation in our TIA clinic.Methods: In consecutive patients evaluated in our TIA clinic from 01/2012 to 11/2013, we prospectively collected delays from onset to arrival, baseline characteristics, discharge diagnosis and recurrent BI at 1 week. Referring pathways were dichotomized between office-based physicians (OBP) and emergency departments (ED). Univariate and multivariate logistic regression were performed.Results: 354 patients were evaluated. Mean (+/â SD) age was 61 years (+/â18). Median (IQR) ABCD2 score was 3 (2â4). Median (IQR) delay from onset to evaluation was 8 h (4â48). Overall, 185 (52%) were referred by OBP vs. 169 (48%) by ED. Evaluation was initiated within 12 h among 201 (57%) patients. After logistic regression, OBP referral was by comparison with ED the only independent factor associated with an evaluation delay >12 h (OR 5.7, 95% CI: 3.5â9.3, p < 0.0001).Conclusion: Our results suggest that preliminary assessment by OBP may increase the delay to initiate the emergent evaluation of TIA patients. Promoting direct admission to TIA clinics through ED may be an efficient alternative for high risk TIAs
Vectorisation of agrochemicals via amino acid carriers: influence of the spacer arm structure on the phloem mobility of phenylpyrrole conjugates in the Ricinus system: Vectorization of agrochemicals via amino acid carriers in the Ricinus system
International audienceBACKGROUND: Excessive agrochemical use causes significant threats to environmental safety and human health. Reducing pesticide use without reducing yield is necessary for sustainable agriculture. Therefore we developed a vectorization strategy to enhance agrochemical delivery through plant amino acid carriers.RESULTS: In addition to a fenpiclonil conjugate recently described, three new amino acid conjugates were synthesized by coupling fenpiclonil to an L-α-amino acid. Phloem mobility of these conjugates which exhibit different structures of the spacer arm introduced between fenpiclonil and the α-amino acid function, was studied using the Ricinus model. Conjugate L-14 which contains a triazole ring with the shortest amino acid chain showed the best phloem systemicity among the four conjugates. By contrast, removing the triazole ring in the spacer arm did not improve systemicity. L-14 exhibited phloem systemicity at all reported pH values (pHs from 5.0 to 6.5) of the foliar apoplast, while acidic derivatives of fenpiclonil were translocated only at pH values near 5.0.CONCLUSION: The conjugates were recognized by a pH-dependent transporter system and translocated at distance in the phloem. They exhibited a broader ability to phloem systemicity than fenpiclonil acidic derivatives within the pH value range of the foliar apoplast
Homogénéisation de l'écoulement dans une cellule de Hele-Shaw et caractérisation par ”PIV en champ large
Dans les capteurs biologiques basĂ©s sur la microfluidique, l'analyte d'intĂ©rĂȘt est en gĂ©nĂ©ral amenĂ© en contact avec une surface fonctionnalisĂ©e oĂč il est capturĂ©. Cette surface est ensuite analysĂ©e par mesure optique (SPR...) ou acoustique (QCM...), permettant ainsi de quantifier prĂ©cisĂ©ment les analytes prĂ©sents dans le liquide. Notre groupe dĂ©veloppe des capteurs acoustiques Ă base de membranes rĂ©sonantes couplĂ©es qui sont agencĂ©es en matrice pour augmenter la sensibilitĂ© du capteur. Cette architecture nĂ©cessite l'utilisation d'une grande chambre d'analyse, de l'ordre de 1cmx1cm, oĂč les Ă©coulements doivent ĂȘtre contrĂŽlĂ©s pour garantir une bonne homogĂ©nĂ©itĂ© des dĂ©bits sur l'ensemble de la surface du capteur lors de l'insertion ou du renouvellement des fluides dans la cavitĂ©. On limite ainsi les Ă©carts de traitement lors des rĂ©actions de fonctionnalisation, de capture, d'inactivation ou encore lors des Ă©tapes de nettoyage de la surface de capture. Il est dĂšs lors nĂ©cessaire de concevoir des puces microfluidiques oĂč la gĂ©omĂ©trie et les caractĂ©ristiques des fluides permettent un Ă©coulement homogĂšne sans zone morte ou zone de recirculation au sein de la chambre. Ainsi nous avons Ă©tudiĂ© diffĂ©rentes gĂ©omĂ©tries de canaux d'entrĂ©e et de sortie dans une chambre microfluidique de grande surface et de faible profondeur, Ă travers des simulations par Ă©lĂ©ments finis en 2D et par le dĂ©veloppement d'un banc expĂ©rimental de caractĂ©risation d'Ă©coulements. Pour minimiser le volume de l'Ă©chantillon Ă analyser et pour faciliter la diffusion des bio-analytes vers la surface d'interaction, nous avons fixĂ© la hauteur de la chambre Ă 80”m. Dans ces conditions, nous nous plaçons dans un rĂ©gime d'Ă©coulement laminaire et la cavitĂ© microfluidique peut ĂȘtre assimilĂ©e Ă une cellule de Hele-Shaw de 1cm x 1cm de cĂŽtĂ©. La simulation des Ă©coulements par Ă©lĂ©ments finis de ces structures a Ă©tĂ© faite sous COMSOL en utilisant le modĂšle laminaire 2D avec approximation de faible profondeur, qui correspond bien Ă l'Ă©coulement de Hele-Shaw. Nous avons Ă©tudiĂ© 5 configurations diffĂ©rentes en faisant varier le nombre et l'espacement des canaux d'alimentation (1 entrĂ©e/1 sortie, 16 entrĂ©es/1 sortie, 16 entrĂ©es/16 sorties) et la gĂ©omĂ©trie de la chambre (carrĂ©e, losange, bĂ©zier). L'objectif de vitesse moyenne dans la chambre Ă©tait de 200”m/s et l'uniformitĂ© de l'Ă©coulement a Ă©tĂ© Ă©valuĂ©e en observant le profil de vitesse dans diffĂ©rentes sections. Pour l'Ă©tude expĂ©rimentale, les dispositifs microfluidiques ont Ă©tĂ© rĂ©alisĂ©s par microfabrication en salle blanche. Les canaux fluidiques et la chambre sont structurĂ©s dans un substrat de silicium par gravure chimique KOH puis la chambre est refermĂ©e par collage anodique d'un substrat de verre autorisant l'observation optique. La mesure expĂ©rimentale des vitesses d'Ă©coulement a demandĂ© de concevoir un nouveau banc de ”PIV permettant l'observation sur un champ d'un cmÂČ, tout en visualisant, en lumiĂšre blanche, des particules de faible taille. Ces particules en mĂ©lamine ont un diamĂštre de 920 nm pour rĂ©pondre aux contraintes de sĂ©dimentation et de non modification des Ă©coulements. La mesure locale du champ de vitesse est obtenue par corrĂ©lation entre des paires d'images espacĂ©es de 50ms, puis en faisant une moyenne sur 100 paires d'image. Nous prĂ©senterons dans l'exposĂ© la comparaison entre les rĂ©sultats expĂ©rimentaux et numĂ©riques pour les diffĂ©rentes chambres Ă©tudiĂ©es, qui montrent que l'on peut amĂ©liorer, en fonction de la configuration de la chambre, l'homogĂ©nĂ©itĂ© des Ă©coulements d'un facteur d'environ 5 sur 80% de la section
Ostreid herpesvirus 1 detection and relationship with Crassostrea gigas spat mortality in France between 1998 and 2006
Since its molecular characterisation, Ostreid herpesvirus 1 (OsHV-1) has been regularly detected in Crassostrea gigas in France. Although its pathogenicity was demonstrated on larval stages, its involvement during mortality outbreaks at the juvenile stage was highly suspected but not evidenced. To investigate mortality outbreaks, the French National Network for Surveillance and Monitoring of Mollusc Health (REPAMO) carried out two surveys in juvenile C. gigas. The first survey lasted from 1998 to 2006 and was an epidemiological inquiry occurring when oyster farmers reported mortality outbreaks. The second survey, a longitudinal one, was set up in 1998 to complete the network observations on OsHV-1. Data analysis showed a specific pattern of mortality outbreaks associated with OsHV-1 detection. Ostreid herpesvirus 1 detection mainly appeared during the summer, suggesting the influence of the seawater temperature on its occurrence. It mostly presented a patchy distribution in the field in contrast to the nursery. Significant relationship between OsHV-1 detection and spat mortality was found, preferentially in sheltered and closed environments. The longitudinal survey confirmed most of the network observations. Although subsequent works particularly epidemiological surveys would be useful to confirm the causal link between the detection of OsHV-1 and the mortality outbreaks in juvenile C. gigas, the role of OsHV-1 in oyster mortality is progressing
Biotic soil-plant interaction processes explain most of hysteretic soil CO2 efux response to temperature in cross-factorial mesocosm experiment
Ecosystem carbon fux partitioning is strongly infuenced by poorly constrained soil CO2 efux (Fsoil).
Simple model applications (Arrhenius and Q10) do not account for observed diel hysteresis between
Fsoil and soil temperature. How this hysteresis emerges and how it will respond to variation in
vegetation or soil moisture remains unknown. We used an ecosystem-level experimental system to
independently control potential abiotic and biotic drivers of the Fsoil-T hysteresis. We hypothesized
a principally biological cause for the hysteresis. Alternatively, Fsoil hysteresis is primarily driven by
thermal convection through the soil profle. We conducted experiments under normal, fuctuating
diurnal soil temperatures and under conditions where we held soil temperature near constant. We
found (i) signifcant and nearly equal amplitudes of hysteresis regardless of soil temperature regime,
and (ii) the amplitude of hysteresis was most closely tied to baseline rates of Fsoil, which were mostly
driven by photosynthetic rates. Together, these fndings suggest a more biologically-driven mechanism
associated with photosynthate transport in yielding the observed patterns of soil CO2 efux being out
of sync with soil temperature. These fndings should be considered on future partitioning models of
ecosystem respiration.French governmentFrench National Research Agency (ANR)
ANR-10-IDEX-0001-02 PSL
ANR-11-INBS-0001ENSUniversity of Arizona (UofA)Philecology Foundation (Fort Worth, Texas, USA)Thomas R. Brown Family FoundationRegion Ile-de-France
I-05-098/R
2011-11017735European Union (EU)National Science Foundation (NSF)
1417101
1331408European Union (EU)
625988UofA Office of Global InitiativesOffice of the Vice President of Research at the UofAUMI iGLOBES program at the Uof
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