Los microbios "invisibles"

Los descubrimientos de Pasteur, de Koch y de sus discípulos, parecían, hace algunos años no haber arrancado más que en parte, el secreto de la «virulencia». Después de haber conseguido evidenciar los parásitos del carbunclo, del muermo, de la tuberculosis, se buscaban en vano los misteriosos agentes de la fiebre aftosa, de la clavelèe, de la rabia... pero aún sin conocerlos, no se dudaba de su naturaleza viviente y figurada.Facultad de Ciencias Agrarias y Forestale

Temperature dependence of the thermal boundary resistivity of glass-embedded metal nanoparticles

The temperature dependence of the thermal boundary resistivity is investigated in glass-embedded Ag particles of radius 4.5 nm, in the temperature range from 300 to 70 K, using all-optical time-resolved nanocalorimetry. The present results provide a benchmark for theories aiming at explaining the thermal boundary resistivity at the interface between metal nanoparticles and their environment, a topic of great relevance when tailoring thermal energy delivery from nanoparticles as for applications in nanomedicine and thermal management at the nanoscaleComment: 4 pages, 3 figure

Scattering and delay time for 1D asymmetric potentials: the step-linear and the step-exponential cases

We analyze the quantum-mechanical behavior of a system described by a one-dimensional asymmetric potential constituted by a step plus (i) a linear barrier or (ii) an exponential barrier. We solve the energy eigenvalue equation by means of the integral representation method, classifying the independent solutions as equivalence classes of homotopic paths in the complex plane. We discuss the structure of the bound states as function of the height U_0 of the step and we study the propagation of a sharp-peaked wave packet reflected by the barrier. For both the linear and the exponential barrier we provide an explicit formula for the delay time \tau(E) as a function of the peak energy E. We display the resonant behavior of \tau(E) at energies close to U_0. By analyzing the asymptotic behavior for large energies of the eigenfunctions of the continuous spectrum we also show that, as expected, \tau(E) approaches the classical value for E -> \infty, thus diverging for the step-linear case and vanishing for the step-exponential one.Comment: 14 pages, 10 figure

Temperature dependence of polarization relaxation in semiconductor quantum dots

The decay time of the linear polarization degree of the luminescence in strongly confined semiconductor quantum dots with asymmetrical shape is calculated in the frame of second-order quasielastic interaction between quantum dot charge carriers and LO phonons. The phonon bottleneck does not prevent significantly the relaxation processes and the calculated decay times can be of the order of a few tens picoseconds at temperature $T \simeq 100$K, consistent with recent experiments by Paillard et al. [Phys. Rev. Lett. {\bf86}, 1634 (2001)].Comment: 4 pages, 4 figure

Peste aviaire ou maladie de Newcastle ?

Jacotot Henri, Vallée A. Peste axiaire ou maladie de Newcastle ?. In: Bulletin de l'Académie Vétérinaire de France tome 102 n°4, 1949. pp. 186-188

Le myxome infectieux du Lapin dans les garennes françaises

Jacotot Henri, Vallée A. Le myxome infectieux du Lapin dans les garennes françaises. In: Bulletin de l'Académie Vétérinaire de France tome 106 n°1, 1953. pp. 25-33

Vaccination contre la maladie de Newcastle au moyen du virus formolé en excipient huileux (Première note)

Jacotot Henri, Vallée A. Vaccination contre la maladie de Newcastle au moyen du virus formolé en excipient huileux. (Première note). In: Bulletin de l'Académie Vétérinaire de France tome 112 n°6, 1959. pp. 373-378

Vaccination contre la maladie de Newcastle au moyen du virus formulé en excipient huileux (deuxième note)

Le pouvoir immunigène de l’antigène de Newcastle formolé incorporé à l’huile de paraffine est particulièrement élevé et ses effets sont d’une constance remarquable. Une seule injection sous-cutanée de 1 ml aux poulets de trois semaines et de 2 ml aux adultes induit une solide immunité, d’une durée d’au moins trois mois chez les premiers et de plus d’un an chez les seconds. La stabilité de ce vaccin est de plusieurs années à la glacière (4-6°) et de plus d’une année à la température du laboratoire (18-20°). Il est bien toléré par les tissus de la poule qui le résorbent en un petit nombre de semaines, et presque toujours sans constituer de granulome.Jacotot Henri, Vallée A. Vaccination contre la maladie de Newcastle au moyen du virus formolé en excipient huileux (Deuxième note). In: Bulletin de l'Académie Vétérinaire de France tome 115 n°8, 1962. pp. 309-311

Challenges for creating magnetic fields by cosmic defects

We analyse the possibility that topological defects can act as a source of magnetic fields through the Harrison mechanism in the radiation era. We give a detailed relativistic derivation of the Harrison mechanism at first order in cosmological perturbations, and show that it is only efficient for temperatures above T ~ 0.2 keV. Our main result is that the vector metric perturbations generated by the defects cannot induce vorticity in the matter fluids at linear order, thereby excluding the production of currents and magnetic fields. We show that anisotropic stress in the matter fluids is required to source vorticity and magnetic fields. Our analysis is relevant for any mechanism whereby vorticity is meant to be transferred purely by gravitational interactions, and thus would also apply to dark matter or neutrinos.Comment: 9 pages, 1 figure; minor corrections and additions; accepted for publication in Physical Review