The lipid content and fatty acid composition of hatched second stage juveniles of Globodera rostochiensis and G. pallida

Les juvéniles de deuxième stade (J2) de #Globodera rostochiensis$âgés d'un jour (éclos dans les diffusats de racines de pomme de terre) contiennent en moyenne 29,2$ en contiennent en moyenne 27,2%. Les lipides des J2 de #G. rostochiensis$J2 sont composés de 72,8$ J2 sont composés de 73,0% de lipides neutres, 13,2% d'acides gras libres et 13,8% de phospholipides. 77,4% des acides gras totaux de #G. rostochiensis$et 80,6$ sont insaturés. Les deux espèces présentent un profil d'acides gras similaire. Vingt acides gras ont été identifiés, allant de C14 à C22 ; les principales classes de lipides sont surtout composées d'acides gras en C20 (50-60%) et C18 (30-35%). Les trois acides gras les plus abondants caractérisés chez les deux espèces sont C20:4, C20:1 et C18:1, représentant à eux seuls plus de 60% du total. Les J2 de #G. rostochiensis$ récoltés toutes les 24 heures au cours des première et seconde semaines après l'exposition aux PRD, présentent la même composition en acides gras que les J2 récoltés toutes les 96 heures pendant les troisième et quatrième semaines. (Résumé d'auteur

Identification and localisation of chitinases induced in the roots of potato plants infected with the potato cyst nematode Globodera pallida

L'analyse par électro-transfert d'extraits provenant de racines de pomme de terre infestées par le nématode à kyste #Globodera pallida$ et leur marquage par un anticorps polyclonal contre les chitinases a révélé l'induction et l'augmentation de l'intensité de plusieurs bandes correspondant aux chitinases et ayant une masse moléculaire s'étageant de 18 à 80 kDa. L'immuno-marquage par l'anticorps de sections de racines infestées a démontré la localisation extracellulaire des chitinases et leur concentration dans le cortex, l'endoderme et le péricycle. Le rôle de ces chitinases dans le contexte de défense de la plante contre les attaques d'agents pathogènes est discuté. (Résumé d'auteur

Immunocytochemical studies on the occurence of gamma-aminobutyric acid in the nervous system of the nematodes Panagrellus redivivus, Meloidogyne incognita and Globodera rostochiensis

Un antisérum polyclonal a été utilisé en immunofluorescence indirecte pour démontrer la présence d'acide gamma-aminobutyrique - un inhibiteur possible de la transmission de l'influx nerveux aux muscles - chez #Panagrellus redevivus et chez les juvéniles de deuxième stade (J2) de #Meloidogyne incognita. Chez #P. redivivus, il a été observé une immunoréactivité, présumée GABA, dans la corde nerveuse dorsale, dans la corde ventrale ainsi que dans certaines cellules nerveuses et les commissures qui ceinturent le nématode entre les cordes nerveuses. Une immunoréactivité a été également observée autour du pharynx et dans l'anneau nerveux. Chez les J2 de #M. incognita, on a détecté cette immunoréactivité dans les nerfs et les cellules de la corde nerveuse ventrale. La coloration à l'immunogold après inclusion de J2 de #Globodera rostochiensis$ traités à l'osmium a montré une immunoréactivité, présumée GABA, dans les procès de neurones des cordes nerveuses ventrale et dorsale, et dans le cytoplasme et le noyau de certaines cellules de la corde ventrale. La position de ces neurones dans les cordes nerveuses indique qu'ils sont probablement des neurones moteur inhibiteurs. Dans l'anneau nerveux, l'immunoréactivité a été observée dans les procès neuronaux et dans un corps cellulaire, probablement le neurone moteur de l'anneau ventral. (Résumé d'auteur

Late reoperation in vascular surgery

Objectives:Assessment of late reoperation (after 30 days) following vascular surgery.Design:Analysis of a prospectively collected database of consecutive patients undergoing vascular surgery.Setting:A single teaching unit's experience between 1986–1993.Materials:Patients undergoing 2501 primary arterial reconstructions.Chief outcome measures:Reoperation after 30 days.Main results:One hundred and fifty eight patients (6%) underwent further operations, at more than 1 month after the primary procedure. Primary procedures at highest risk for reoperations were axillobifemoral bypasses and femorodistal bypasses with respective late reoperation rates of 20% and 16%. The majority of patients required late reoperation because of graft occlusion or stenosis. Overall, of the 158 late reoperations performed, 114 were related to the same arterial segment with the same presenting symptoms as the primary operation, and 44 for a different indication. A second or subsequent reoperation was required in 54 patients and the overall operative mortality was 11%.Conclusion:Patients undergoing certain vascular procedures, should be informed of the high risk of a subsequent procedure when consent is obtained

An SO(10)XS-4 Scenario for Naturally Degenerate Neutrinos

The simplest scenario for the three known light neutrinos that fits the solar and atmospheric neutrino deficit and a mixed dark matter (MDM) picture of the universe requires them to be highly degenerate with $m_{\nu} \sim$ 1 - 2 eV. We propose an SO(10) grand unified model with an S$_{4}$-horizontal symmetry that leads naturally to such a scenario. An explicit numerical analysis of the quark and lepton sector of the model shows that it can lead to desired mass differences to fit all data only for the small angle non-adiabatic MSW solution to the solar neutrino puzzle.Comment: UMD-PP-94-95; (Latex file; 1 figure available on request

Viking Afterbody Heating Computations and Comparisons to Flight Data

Computational fluid dynamics predictions of Viking Lander 1 entry vehicle afterbody heating are compared to flight data. The analysis includes a derivation of heat flux from temperature data at two base cover locations, as well as a discussion of available reconstructed entry trajectories. Based on the raw temperature-time history data, convective heat flux is derived to be 0.63-1.10 W/sq cm for the aluminum base cover at the time of thermocouple failure. Peak heat flux at the fiberglass base cover thermocouple is estimated to be 0.54-0.76 W/sq cm, occurring 16 seconds after peak stagnation point heat flux. Navier-Stokes computational solutions are obtained with two separate codes using an 8-species Mars gas model in chemical and thermal non-equilibrium. Flowfield solutions using local time-stepping did not result in converged heating at either thermocouple location. A global time-stepping approach improved the computational stability, but steady state heat flux was not reached for either base cover location. Both thermocouple locations lie within a separated flow region of the base cover that is likely unsteady. Heat flux computations averaged over the solution history are generally below the flight data and do not vary smoothly over time for both base cover locations. Possible reasons for the mismatch between flight data and flowfield solutions include underestimated conduction effects and limitations of the computational methods

Magnetic Field Generation in Stars

Enormous progress has been made on observing stellar magnetism in stars from the main sequence through to compact objects. Recent data have thrown into sharper relief the vexed question of the origin of stellar magnetic fields, which remains one of the main unanswered questions in astrophysics. In this chapter we review recent work in this area of research. In particular, we look at the fossil field hypothesis which links magnetism in compact stars to magnetism in main sequence and pre-main sequence stars and we consider why its feasibility has now been questioned particularly in the context of highly magnetic white dwarfs. We also review the fossil versus dynamo debate in the context of neutron stars and the roles played by key physical processes such as buoyancy, helicity, and superfluid turbulence,in the generation and stability of neutron star fields. Independent information on the internal magnetic field of neutron stars will come from future gravitational wave detections. Thus we maybe at the dawn of a new era of exciting discoveries in compact star magnetism driven by the opening of a new, non-electromagnetic observational window. We also review recent advances in the theory and computation of magnetohydrodynamic turbulence as it applies to stellar magnetism and dynamo theory. These advances offer insight into the action of stellar dynamos as well as processes whichcontrol the diffusive magnetic flux transport in stars.Comment: 41 pages, 7 figures. Invited review chapter on on magnetic field generation in stars to appear in Space Science Reviews, Springe

Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

The $B^0$-$\bar B^0$ oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives $\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.Comment: 7 pages, 1 figure, submitted to Physical Review Letter