Exact Keldysh theory of strong-field ionization: residue method vs saddle-point approximation

In recent articles [Mishima et al., Phys. Rev. A, 66, 033401(2002); Chao, Phys. Rev. A, 72, 053414 (2005)] it was proposed to use the residue theorem for the exact calculation of the transition amplitude describing strong-field ionization of atomic systems within Keldysh theory. This should avoid the necessity to apply the method of steepest descent (saddle-point approximation). Comparing the results of both approaches for atomic hydrogen a difference by a factor of 2 was found for the 1s, and an even more drastic deviation for the 2s state. Thus it was concluded that the use of the saddle-point approximation is problematic. In this work the deviations are explained and it is shown that the previous conclusion is based on an unjustified neglect of an important contribution occurring in the application of the residue theorem. Furthermore, the applicability of the method of steepest descent for the ionization of Rydberg states is discussed and an improvement of the standard result is suggested that successfully removes the otherwise drastic failure for large principal quantum numbers.Comment: 7 pages, 3 figures, 1 tabl

Extremal Black Attractors in 8D Maximal Supergravity

Motivated by the new higher D-supergravity solutions on intersecting attractors obtained by Ferrara et al. in [Phys.Rev.D79:065031-2009], we focus in this paper on 8D maximal supergravity with moduli space [SL(3,R)/SO(3)]x[SL(2,R)/SO(2)] and study explicitly the attractor mechanism for various configurations of extremal black p- branes (anti-branes) with the typical near horizon geometries AdS_{p+2}xS^{m}xT^{6-p-m} and p=0,1,2,3,4; 2<=m<=6. Interpretations in terms of wrapped M2 and M5 branes of the 11D M-theory on 3-torus are also given. Keywords: 8D supergravity, black p-branes, attractor mechanism, M-theory.Comment: 37 page

Experimental stylolites in quartz and modeled application to natural structures.

Experimental stylolites have been observed at stressed contacts between quartz grains loaded for a period of several months in presence of aqueous silica solution, at 350°C under 50 MPa of differential stress. Stereoscopic analysis of pairs of SEM images, processed in the same way as earth-surface elevation data gives the stylolites topography. Coupled with observations of closed interactions between dissolution pits and stylolitic peaks, these data illuminate the mechanism of stylolite formation. The complex geometry of stylolite surfaces is imposed by the interplay between the development of dissolution peaks in favored locations (fast dissolution pits) and the mechanical properties of the solid-fluid-solid interfaces. Simple mechanical modeling expresses the crucial competition that could rule the development of stylolites: (i) a stress related process (modeled as the stiffness of springs (N/m3) activates the heterogeneous dissolution rates of the solid interface that promotes the deflection. In parallel, (ii) the strength of the solid interface, modeled as the stiffness of a membrane (N/m) and equivalent to a surface tension) limits the deflection and is opposed to its development. The modeling produces stylolitic surfaces with characteristic geometries that vary from conical to columnar shaped stylolites when both the effect of dissolution-rate heterogeneity and the strength properties of the rock are included

Étude du régime alimentaire de deux souches de truite arc-en-ciel marocaine et bulgare dans deux plans d'eau du Moyen-Atlas Amghass I et Amghass II

Le présent travail porte sur l'étude du régime alimentaire de deux souches de truites arc-en-ciel : la souche marocaine issue de croisements de truites arc-en-ciel en provenance d'Europe et d'Amérique du nord et la souche bulgare introduite au Maroc en 1987. Les milieux d'étude sont deux plans d'eau du Moyen-Atlas marocain (Amghass I et Amghass II) présentant des eaux de bonne qualité physique et chimique et une diversité biologique (invertébrés) assez importante. Afin de déterminer les préférences alimentaires de ces deux souches nous avons évalué : le spectre alimentaire, déterminé par les abondances relatives, les coefficients d'occurrence des proies ingérées, l'indice alimentaire de Lauzanne pour les différentes catégories de proies et l'intensité de prédation des truites.Les résultats ont montré une similitude au niveau des régimes alimentaires des deux souches caractérisés par une nette préférence pour les larves et nymphes d'Insectes considérées comme proies essentielles.This current work is about the study of the dietary regime of two species of rainbow trout. The Moroccan kind is a cross breed of the European and North American Rainbow trout and the Bulgarian trout introduced into Morocco since 1987.The environments of study are two stretches of water in the "Moyen-Atlas" (Amghass I and Amghass II), which present water of good physical and chemical quality and are of quite important biological diversity.To determine the dietary preferences of the two species, we evaluated several parameters: the dietary spectrum which is determined by the relative abundance and the coefficient of occurence of ingested prey, the index alimentary of Lauzanne for the different categories of prey and how predatory the trout areThe results have shown a similarity in the level of dietary regimes of the two populations outlined by a clear preference for larvae and nymph insects which are considered to be essential prey

Study of polyphenols of the leaves of an ibero moroccan endemic, Thymelaea lythroides.

Study of polyphenols of the leaves of an ibero moroccan endemic, Thymelaea lythroides. Thymelaea lythroides (Thymelaeacees) is an endemic of the region of the Gharb (forest of Mamora). It is part of the panoply of the medicinal and aromatic plants of Morocco. Because of the lack of phytochemical informations on the species, some previous studies had for object a research of the antifungal activity of its extracts and a phytochemical screening. This last permitted to put in evidence the wealth of the plant in different secondary compounds. Thus, the present work intends to study the polyphenols of the leaves of Thymelaea lythroides and specially the flavonics aglycones and the anthocyanidins. The survey demonstrated the existence of different molecules belonging to the class of the flavonols, whose identification revealed the kaempferol and quercetine. In addition to two acidic phenols, identified as the cofeique acid and the genticique acidic and two anthocyanidins, the delphinidine and the cyanidine

Effects of cutting origin and exogenous auxin treatment on the rooting of Rosa damascena (Mill) cuttings from the M’goun-Dades valleys in Morocco

The Rosa damascena (Mill), commonly known as Damask rose, is one of the most important Rosa species with great economic interest on a national and international scale. In Morocco, especially in M’goun and Dades valleys, the Damask rose is mainly propagated by replanting rooted shoots. However, this method is presenting several constraints. Considering this fact, this study was undertaken to investigate the influence of two major factors: the origin of cutting and the effect of the auxin treatment on Rosa damascena cutting. For this purpose, the cuttings from seven localities were cultivated in a greenhouse under controlled conditions after soaking treatment in different concentrations of Butyric Indole Acid (0; 2000 and 4000 ppm). The obtained results revealed a significant (P<0,01) difference between the seven localities for the focused parameters. In fact, the individuals belonging to the same morphotype act in the same way with regard to cutting. The rooting rate varies between 10% and 70% depending on the origin of cuttings and the applied concentration of IBA. The results of this study showed that propagation of Rosa damascena by cuttings can promote this culture. However, the optimization of this method is linked to the choice of the plant, the origin of cuttings in particular to the chosen ecotypes.

Study of volatile compounds of Pyrus mamorensis Trab. a characteristic plant of Mamora forest (north-western Morocco)

Pyrus mamorensis Trab. commonly called “wild pear” was considered for long time as an endemic of the Mamora forest of Morocco (north-west). Although lack of protection and it is threatened with extinction in its range, this tree is of great interest due to its ecological and medicinal properties. This study focused on evaluation of volatiles in Pyrus mamorensis for its valorisation as a natural resource. So, the volatile compounds from different parts (leaves, stems, fruits, and flowers) were investigated after extraction by cold maceration in ethyl ether and analyzed by gas chromatography coupled to the mass spectrometry (GC - MS). Thirty one (31) compounds were identified and quantified including fifteen (15) terpenes, seven (7) alcans, two (2) aldehydes, four (4) esters and three (3) allyl alkoxybenzen derivatives. Estragol was the dominant component of the plant and that was only detected in leaves (83,09 %), while hexadecane (36,92 %) and allyl hexanoate (29,39 %) were mainly detected in the stems. The fruits showed relatively high levels (20,59 %) of benzyl butanoate, whereas in the flowers, limonene is the most abundant constituent (30,12 %). The analysis of the relative rates of different classes of volatile compounds, revealed the diversity of these compounds in P. mamorensis compared to two cultivars of edible species : P. communis L. et P. pyrifolia. The significant difference in composition in this case could be due to the wild character of P. mamorensis