Effects of burying and removing dead leaves from the ground on the development of scab epidemics in an apple organic orchard.

Ascospores produced on scabbed leaves in the leaf litter constitute the primary inoculum causing scab infections in apple orchards during the year. The trial, carried out in a commercial organic orchard, permitted to evaluate the effects of the removal of dead leaves located on the inter-row supplemented by the ploughing in of the leaves left on the row, on the development of scab epidemics. From the first recorded contamination to harvest time, lesions on leaves and fruits were counted to determine reduction in disease incidence and severity, compared with the untreated plots. Disease severity as a function of the distance from the untreated plot was also observed, to evaluate the spore dispersal gradient within the orchard. The results show that the ploughing in and the removal of the litter reduced disease incidence by 62% on leaves, and by almost 82% on fruits to harvest. Moreover, measurements of the dispersal gradient show that the spores do not disperse, or little, beyond 20m of the untreated zone

Воздействие альтернативных источников энергии на жизнь человека, перспективы развития в России

Альтернативной энергетике вполне по силам обеспечить энергетическую, экологическую и продовольственную безопасность населения страны на длительную перспективу. Ведь количество энергии, которую человек может уловить, аккумулировать и использовать, всегда оптимально. Данный вид энергетики в основном использует прямую энергию солнца и опосредованно применяется энергия ветра, приливов, отливов, биомассы, геотермальная энергия. В данной статье исследованы перспективы развития альтернативной энергетики в пределах территории России, влияние альтернативной энергетики на жизнь людей, а так же те глобальные проблемы, которые могут быть решены при помощи планового введения альтернативной энергетики. Целью данной работы является выявление явных преимущество альтернативных видов энергетики перед традиционными

When stereotype threat does not impair performance, self-affirmation can be harmful

International audienc

Effect of a magnetic field on the two-phonon Raman scattering in graphene

We have studied, both experimentally and theoretically, the change of the so-called 2D band of the Raman scattering spectrum of graphene (the two-phonon peak near 2700 cm-1) in an external magnetic field applied perpendicular to the graphene crystal plane at liquid helium temperature. A shift to lower frequency and broadening of this band is observed as the magnetic field is increased from 0 to 33 T. At fields up to 5--10 T the changes are quadratic in the field while they become linear at higher magnetic fields. This effect is explained by the curving of the quasiclassical trajectories of the photo-excited electrons and holes in the magnetic field, which enables us (i) to extract the electron inelastic scattering rate, and (ii) to conclude that electronic scattering accounts for about half of the measured width of the 2D peak.Comment: 11 pages, 7 figure

The enormous outer Galaxy HII region CTB 102

We present new radio recombination line observations of the previously unstudied HII region CTB 102. Line parameters are extracted and physical parameters describing the gas are calculated. We estimate the distance to CTB 102 to be 4.3 kpc. Through comparisons with HI and 1.42 GHz radio continuum data, we estimate the size of CTB 102 to be 100-130 pc, making it one of the largest HII regions known, comparable to the W4 complex. A stellar wind blown bubble model is presented as the best explanation for the observed morphology, size and velocities.Comment: 26 pages, 8 figures. Accepted for publication by The Astrophysical Journa

Multidomain spectral method for the Gauss hypergeometric function

We present a multidomain spectral approach for Fuchsian ordinary differential equations in the particular case of the hypergeometric equation. Our hybrid approach uses Frobenius’ method and Moebius transformations in the vicinity of each of the singular points of the hypergeometric equation, which leads to a natural decomposition of the real axis into domains. In each domain, solutions to the hypergeometric equation are constructed via the well-conditioned ultraspherical spectral method. The solutions are matched at the domain boundaries to lead to a solution which is analytic on the whole compactified real line R∪∞ , except for the singular points and cuts of the Riemann surface on which the solution is defined. The solution is further extended to the whole Riemann sphere by using the same approach for ellipses enclosing the singularities. The hypergeometric equation is solved on the ellipses with the boundary data from the real axis. This solution is continued as a harmonic function to the interior of the disk by solving the Laplace equation in polar coordinates with an optimal complexity Fourier–ultraspherical spectral method. In cases where logarithms appear in the solution, a hybrid approach involving an analytical treatment of the logarithmic terms is applied. We show for several examples that machine precision can be reached for a wide class of parameters, but also discuss almost degenerate cases where this is not possible

Fronts and interfaces in bistable extended mappings

We study the interfaces' time evolution in one-dimensional bistable extended dynamical systems with discrete time. The dynamics is governed by the competition between a local piece-wise affine bistable mapping and any couplings given by the convolution with a function of bounded variation. We prove the existence of travelling wave interfaces, namely fronts, and the uniqueness of the corresponding selected velocity and shape. This selected velocity is shown to be the propagating velocity for any interface, to depend continuously on the couplings and to increase with the symmetry parameter of the local nonlinearity. We apply the results to several examples including discrete and continuous couplings, and the planar fronts' dynamics in multi-dimensional Coupled Map Lattices. We eventually emphasize on the extension to other kinds of fronts and to a more general class of bistable extended mappings for which the couplings are allowed to be nonlinear and the local map to be smooth.Comment: 27 pages, 3 figures, submitted to Nonlinearit

TRIDENT: an Infrared Differential Imaging Camera Optimized for the Detection of Methanated Substellar Companions

A near-infrared camera in use at the Canada-France-Hawaii Telescope (CFHT) and at the 1.6-m telescope of the Observatoire du Mont-Megantic is described. The camera is based on a Hawaii-1 1024x1024 HgCdTe array detector. Its main feature is to acquire three simultaneous images at three wavelengths across the methane absorption bandhead at 1.6 microns, enabling, in theory, an accurate subtraction of the stellar point spread function (PSF) and the detection of faint close methanated companions. The instrument has no coronagraph and features fast data acquisition, yielding high observing efficiency on bright stars. The performance of the instrument is described, and it is illustrated by laboratory tests and CFHT observations of the nearby stars GL526, Ups And and Chi And. TRIDENT can detect (6 sigma) a methanated companion with delta H = 9.5 at 0.5" separation from the star in one hour of observing time. Non-common path aberrations and amplitude modulation differences between the three optical paths are likely to be the limiting factors preventing further PSF attenuation. Instrument rotation and reference star subtraction improve the detection limit by a factor of 2 and 4 respectively. A PSF noise attenuation model is presented to estimate the non-common path wavefront difference effect on PSF subtraction performance.Comment: 41 pages, 16 figures, accepted for publication in PAS

A Number-Theoretic Error-Correcting Code

In this paper we describe a new error-correcting code (ECC) inspired by the Naccache-Stern cryptosystem. While by far less efficient than Turbo codes, the proposed ECC happens to be more efficient than some established ECCs for certain sets of parameters. The new ECC adds an appendix to the message. The appendix is the modular product of small primes representing the message bits. The receiver recomputes the product and detects transmission errors using modular division and lattice reduction