Dissipative structure formation in cold-rolled Fe and Ni during heavy ion irradiation

We report 4-probe resistivity measurements of cold-rolled Ni and Fe during 100 MeV oxygen ion irradiation, at 300K. The resistivity shows increase and saturation, marked by jumps. Employing 200 MeV silver ion irradiation of Fe and Si(100) and topographically identifying strain at an artificial interface in the latter, we assign the resistivity behavior to atomic rearrangements arising from dissipation of incident ion energy at internal interfaces of Ni and Fe, with positive feedback.}Comment: RevTex+ 7 Postscript figures; Fig 2 (topograph) available on demand to [email protected]. To appear in Phys Rev Let

Spindle Assembly Checkpoint Protein Dynamics Reveal Conserved and Unsuspected Roles in Plant Cell Division

Background: In eukaryotes, the spindle assembly checkpoint (SAC) ensures that chromosomes undergoing mitosis do not segregate until they are properly attached to the microtubules of the spindle. Methodology/Principal Findings: We investigated the mechanism underlying this surveillance mechanism in plants, by characterising the orthogolous SAC proteins BUBR1, BUB3 and MAD2 from Arabidopsis. We showed that the cell cycle-regulated BUBR1, BUB3.1 and MAD2 proteins interacted physically with each other. Furthermore, BUBR1 and MAD2 interacted specifically at chromocenters. Following SAC activation by global defects in spindle assembly, these three interacting partners localised to unattached kinetochores. In addition, in cases of 'wait anaphase', plant SAC proteins were associated with both kinetochores and kinetochore microtubules. Unexpectedly, BUB3.1 was also found in the phragmoplast midline during the final step of cell division in plants. Conclusions/Significance: We conclude that plant BUBR1, BUB3.1 and MAD2 proteins may have the SAC protein functions conserved from yeast to humans. The association of BUB3.1 with both unattached kinetochore and phragmoplast suggests that in plant, BUB3.1 may have other roles beyond the spindle assembly checkpoint itself. Finally, this study of the SAC dynamics pinpoints uncharacterised roles of this surveillance mechanism in plant cell division

Inhibition of IL-10 Production by Maternal Antibodies against Group B Streptococcus GAPDH Confers Immunity to Offspring by Favoring Neutrophil Recruitment

Group B Streptococcus (GBS) is the leading cause of neonatal pneumonia, septicemia, and meningitis. We have previously shown that in adult mice GBS glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an extracellular virulence factor that induces production of the immunosuppressive cytokine interleukin-10 (IL-10) by the host early upon bacterial infection. Here, we investigate whether immunity to neonatal GBS infection could be achieved through maternal vaccination against bacterial GAPDH. Female BALB/c mice were immunized with rGAPDH and the progeny was infected with a lethal inoculum of GBS strains. Neonatal mice born from mothers immunized with rGAPDH were protected against infection with GBS strains, including the ST-17 highly virulent clone. A similar protective effect was observed in newborns passively immunized with anti-rGAPDH IgG antibodies, or F(ab')2 fragments, indicating that protection achieved with rGAPDH vaccination is independent of opsonophagocytic killing of bacteria. Protection against lethal GBS infection through rGAPDH maternal vaccination was due to neutralization of IL-10 production soon after infection. Consequently, IL-10 deficient (IL-10−/−) mice pups were as resistant to GBS infection as pups born from vaccinated mothers. We observed that protection was correlated with increased neutrophil trafficking to infected organs. Thus, anti-rGAPDH or anti-IL-10R treatment of mice pups before GBS infection resulted in increased neutrophil numbers and lower bacterial load in infected organs, as compared to newborn mice treated with the respective control antibodies. We showed that mothers immunized with rGAPDH produce neutralizing antibodies that are sufficient to decrease IL-10 production and induce neutrophil recruitment into infected tissues in newborn mice. These results uncover a novel mechanism for GBS virulence in a neonatal host that could be neutralized by vaccination or immunotherapy. As GBS GAPDH is a structurally conserved enzyme that is metabolically essential for bacterial growth in media containing glucose as the sole carbon source (i.e., the blood), this protein constitutes a powerful candidate for the development of a human vaccine against this pathogen

Senegal: Presidential elections 2019 - The shining example of democratic transition immersed in muddy power-politics

Whereas Senegal has long been sold as a showcase of democracy in Africa, including peaceful political alternance, things apparently changed fundamentally with the Senegalese presidentials of 2019 that brought new configurations. One of the major issues was political transhumance that has been elevated to the rank of religion in defiance of morality. It threatened political stability and peace. In response, social networks of predominantly young activists, created in 2011 in the aftermath of the Arab Spring focused on grass-roots advocacy with the electorate on good governance and democracy. They proposed a break with a political system that they consider as neo-colonialist. Moreover, Senegal’s justice is frequently accused to be biased, and the servility of the Constitutional Council which is in the first place an electoral court has often been denounced

ÉTUDE DE CENTRES PROFONDS DANS CdTe PAR DES MÉTHODES DE PHOTOCAPACITANCE

Une étude des centres profonds dans CdTe de type n, purifié par fusion de zone, a été menée à l'aide de mesures de photocapacitance utilisant une diode de Schottky Au-CdTe portée à 77 K. L'analyse détaillée des variations temporelles de la capacité permet de séparer les contributions de plusieurs niveaux et de caractériser chacun par sa position, sa section optique efficace et sa concentration. On met ainsi en évidence : 1) un centre comportant deux niveaux : l'un à Ec — 0,58 eV, l'autre à une énergie supérieure avec une concentration de 7,8 x 1011 cm-3, 2) un centre plus profond à Ec — 0,93 eV et une concentration de 5,4 x 1012 cm-3, 3) un niveau entouré d'une barrière de potentiel pour les électrons situé à Ec — 0,54 eV. Ces résultats sont interprétés en termes de centres double donneur et accepteur multiple. Cette assignation soulève le problème intéressant de la correspondance avec les défauts natifs prévus : VTe(ou Cdi) qui serait un donneur double et VCd qui serait un double accepteur.A study of deep centers in zone refined n type CdTe has been conducted by means of photocapacitance measurements performed on a Au-CdTe Schottky diode at the temperature of 77 K. The detailed analysis of the time variations of capacity allows us to separate the contributions of several centers and to determine for each one the level position, the optical cross section and the concentration. In this way we observe the following : 1) a center with two associated levels : one at Ec — 0.58 eV, the other one at a higher energy with a concentration of 7.8 x 1011 cm-3, 2) a deeper center at Ec — 0.93 eV with a concentration of 5.4 x 1012 cm-3, 3) a level surmonted by a potential barrier for electrons, located at Ec — 0.54 eV. These results are interpreted in terms of double donor and multiple acceptor centers. This assignment raises the interesting problem of the connection with the expected native defects : VTe (or Cdi) and VCd which would be a double donor and a double acceptor respectively