428 research outputs found
Existence chez la pomme de terre de résistance induite vis-à -vis de Globodera rostochiensis
Le mécanisme de résistance à #G. rostochiensis Ro1/4 de deux génotypes ex-#vernei de pomme de terre et leurs parents est étudié selon diverses méthodologies. Les résultats obtenus #in vitro à partir de plantes cultivées en boßte de Petri montrent que la résistance est incomplÚte. Par contre, la résistance mesurée à partir de tests réalisés en pots est analogue à celle induite par le gÚne H1. L'influence possible des exsudats radiculaires sur ces discordances est étudiée et réfutée : pour certains génotypes, l'éclosion est supérieure à celle induite par le témoin ; pour d'autres, elle est inférieure mais la différence mesurée est insuffisante pour expliquer l'ampleur des discordances observées. Les tests #in vitro montrent en fait que l'invasion progressive des juvéniles de #G. rostochiensis induit, à partir d'une certaine quantité de juvéniles, une résistance quasi totale sur toute la longueur de la racine. Cette résistance agit alors également vis-à -vis de #G. pallida. Le rÎle possible des phytoalexines ou de protéines de défense, PR, est envisagé. (Résumé d'auteur
Prototype 9.7 m Schwarzschild-Couder telescope for the Cherenkov Telescope Array: status of the optical system
The Cherenkov Telescope Array (CTA) is an international project for a
next-generation ground-based gamma ray observatory, aiming to improve on the
sensitivity of current-generation experiments by an order of magnitude and
provide energy coverage from 30 GeV to more than 300 TeV. The 9.7m
Schwarzschild-Couder (SC) candidate medium-size telescope for CTA exploits a
novel aplanatic two-mirror optical design that provides a large field of view
of 8 degrees and substantially improves the off-axis performance giving better
angular resolution across all of the field of view with respect to
single-mirror telescopes. The realization of the SC optical design implies the
challenging production of large aspherical mirrors accompanied by a
submillimeter-precision custom alignment system. In this contribution we report
on the status of the implementation of the optical system on a prototype 9.7 m
SC telescope located at the Fred Lawrence Whipple Observatory in southern
Arizona.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC
2017), Busan, Korea. All CTA contributions at arXiv:1709.0348
AMPK alpha 1-induced RhoA phosphorylation mediates vasoprotective effect of estradiol
OBJECTIVE: Estradiol (E2) mediates numerous beneficial effects assigned to estrogens, but whereas mechanisms have been described at the endothelial level, direct effects on vascular smooth muscle cells (VSMC) are poorly documented. As evidence accumulates regarding the role of RhoA in vascular pathophysiology and the benefit of RhoA-Rho associated protein kinase (Rock) pathway inhibition, we analyzed if E2 could inhibit it in VSMC. METHODS AND RESULTS: We show that in VSMC, E2 inhibits the RhoA-Rock pathway in a time- and concentration-dependent manner. The inhibition of RhoA-Rock pathway results from E2-induced phosphorylation of the Ser188 of RhoA. Using pharmacological, transfection, and in vitro phosphorylation experiments, we demonstrate that AMP-activated protein kinase subunit alpha 1 (AMPKalpha1) is activated by estrogen receptor stimulation and catalyzes RhoA phosphorylation induced by E2. Ex vivo, ovariectomy leads to an increase in the amplitude of phenylephrine- or serotonine-induced contractions of aortic rings in wild-type mice but not in AMPKalpha1-knock-out mice or E2-supplemented animals. These functional effects were correlated with a reduced level of RhoA phosphorylation in the aorta of ovariectomized female, male, and AMPKalpha1 knock-out mice. CONCLUSION: Our work thus defines AMPKalpha1 as (1) a new kinase for RhoA and (2) a new mediator of the vasoprotective effects of estrogen
Low- and intermediate-temperature ammonia/hydrogen oxidation in a flow reactor: Experiments and a wide-range kinetic modeling
Understanding the chemistry behind the oxidation of ammonia/hydrogen mixtures is crucial for ensuring the flexible use of such mixtures in several applications, related to propulsion systems and power generation. In this work, the oxidation of ammonia/hydrogen blends was investigated through an experimental and kinetic-modeling study, where the low- and intermediate-temperature conditions were considered. An experimental campaign was performed in a flow reactor, at stoichiometric conditions and near-atmospheric pressure (126.7 kPa). The mole fraction of fuels, oxidizer and final products was measured. At the same time, a comprehensive kinetic model was set up, following a modular and hierarchical approach, and implementing the recently-available elementary rates. Such a model was used to interpret the experimental results, and to extend the analysis to literature data, covering several oxidation features. The reactivity boost provided by H2 addition was found to be approximately linear with its mole fraction in both flow- and jet-stirred-reactor conditions (except for the smallest H2 amounts in the flow reactor), in contrast with the more-than-linear increase in the laminar flame speed. The key role of HO2 in regulating fuel conversion and autoignition at low temperature was confirmed for binary mixtures, with H2NO being the bottleneck to the low-temperature oxidation of NH3-rich blends. On the other hand, the nitrogen fate was found to be mostly regulated by NHx + NO propagation and termination channels
Kalinin: an epithelium-specific basement membrane adhesion molecule that is a component of anchoring filaments.
IgG autoantibody to brain beta tubulin III associated with cytokine cluster-II discriminate cerebral malaria in central India
We investigated the significance of these self-reactive antibodies in clinically well-defined groups of P. falciparum infected patients manifesting mild malaria (MM), severe non-cerebral malaria (SM), or cerebral malaria (CM) and in control subjects from Gondia, a malaria epidemic site in central India using quantitative immunoprinting and multivariate statistical analyses. A two-fold complete-linkage hierarchical clustering allows classifying the different patient groups and to distinguish the CM from the others on the basis of their profile of IgG reactivity to brain proteins defined by PANAMA Blot. We identified beta tubulin III (TBB3) as a novel discriminant brain antigen in the prevalence of CM. In addition, circulating IgG from CM patients highly react with recombinant TBB3. Overall, correspondence analyses based on singular value decomposition show a strong correlation between IgG anti-TBB3 and elevated concentration of cluster-II cytokine (IFNÎł, IL1ÎČ, TNFα, TGFÎČ) previously demonstrated to be a predictor of CM in the same populatio
Very-high-energy observations of the binaries V 404 Cyg and 4U 0115+634 during giant X-ray outbursts
Transient X-ray binaries produce major outbursts in which the X-ray flux can
increase over the quiescent level by factors as large as . The low-mass
X-ray binary V 404 Cyg and the high-mass system 4U 0115+634 underwent such
major outbursts in June and October 2015, respectively. We present here
observations at energies above hundreds of GeV with the VERITAS observatory
taken during some of the brightest X-ray activity ever observed from these
systems. No gamma-ray emission has been detected by VERITAS in 2.5 hours of
observations of the microquasar V 404 Cyg from 2015, June 20-21. The upper flux
limits derived from these observations on the gamma-ray flux above 200 GeV of F
cm s correspond to a tiny fraction (about
) of the Eddington luminosity of the system, in stark contrast to that
seen in the X-ray band. No gamma rays have been detected during observations of
4U 0115+634 in the period of major X-ray activity in October 2015. The flux
upper limit derived from our observations is F cm
s for gamma rays above 300 GeV, setting an upper limit on the ratio of
gamma-ray to X-ray luminosity of less than 4%.Comment: Accepted for publication in the Astrophysical Journa
Construction of a Schwarzschild-Couder telescope as a candidate for the Cherenkov Telescope Array: status of the optical system
We present the design and the status of procurement of the optical system of
the prototype Schwarzschild-Couder telescope (pSCT), for which construction is
scheduled to begin in fall at the Fred Lawrence Whipple Observatory in southern
Arizona, USA. The Schwarzschild-Couder telescope is a candidate for the
medium-sized telescopes of the Cherenkov Telescope Array, which utilizes
imaging atmospheric Cherenkov techniques to observe gamma rays in the energy
range of 60Gev-60TeV. The pSCT novel aplanatic optical system is made of two
segmented aspheric mirrors. The primary mirror has 48 mirror panels with an
aperture of 9.6 m, while the secondary, made of 24 panels, has an diameter of
5.4 m. The resulting point spread function (PSF) is required to be better than
4 arcmin within a field of view of 6.4 degrees (80% of the field of view),
which corresponds to a physical size of 6.4 mm on the focal plane. This goal
represents a challenge for the inexpensive fabrication of aspheric mirror
panels and for the precise alignment of the optical system as well as for the
rigidity of the optical support structure. In this submission we introduce the
design of the Schwarzschild-Couder optical system and describe the solutions
adopted for the manufacturing of the mirror panels and their integration with
the optical support structure.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
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