On the Fock Transformation in Nonlinear Relativity

In this paper, we propose a new deformed Poisson brackets which leads to the Fock coordinate transformation by using an analogous procedure as in Deformed Special Relativity. We therefore derive the corresponding momentum transformation which is revealed to be different from previous results. Contrary to the earlier version of Fock's nonlinear relativity for which plane waves cannot be described, our resulting algebra keeps invariant for any coordinate and momentum transformations the four dimensional contraction $p_{\mu} x^{\mu}$, allowing therefore to associate plane waves for free particles. As in Deformed Special Relativity, we also derive a canonical transformation with which the new coordinates and momentum satisfy the usual Poisson brackets and therefore transform like the usual Lorentz vectors. Finally, we establish the dispersion relation for Fock's nonlinear relativity.Comment: 10 pages, no figure

Etude préliminaire de l’ichtyotoxicité des feuilles et tourteau de Balanites aegyptiaca et de tourteau de thé (Camellia sp) en vue de leurs utilisations comme piscicide d’aménagement des étangs piscicoles

Les feuilles et le tourteau de Balanites aegyptiaca et le tourteau de thé ont été étudiés pour leur toxicité au tilapia (Oreochromis niloticus). Les résultats ont notamment montré qu’avec le tourteau de B. aegyptiaca, à la concentration de 25 mg/l, 50% des poissons meurent en 2 heures 47 minutes et 100% meurent en 3 heures 10 minutes. Ces résultats sont de même ordre de grandeur que ceux obtenus avec le tourteau de thé pour lequel 50% des poissons meurent en 2 heures 37 minutes et 100% en 3 heures 23 minutes avec la concentration de 25 mg/l. Avec les macérés des feuilles de B. aegyptiaca, il faut jusqu’à 900 mg/l pour obtenir 50% de morts en 3 heures 37 minutes et 100% de morts en 4 heures 85 minutes. La réalisation des réactions de caractérisation a révélé la présence de 12 groupes chimiques dont des saponisides dans les feuilles de B. aegyptiaca qui pourraient expliquer cette performance d’ichtyotoxicité. Ces résultats suggèrent que le tourteau de B. aegyptiaca pourrait remplacer le tourteau de thé (ou saponine) comme piscicide dans les aménagements piscicoles.Mots clés: Balanites aegyptiaca, ichtyotoxique, feuilles, tourteaux, thé, tilapia d’élevag

Etude de la toxicité des feuilles du pommier de Sodome du Sénégal et du tourteau de graines de thé chez le tilapia du Nil en aménagement piscicole

Les toxicités des feuilles du pommier de Sodome du Sénégal (Calotropis procera) et du tourteau de graines de thé (Camellia sp) chez le tilapia du Nil (Oreochromis niloticus) en pisciculture ont été étudiées. La réalisation des réactions de caractérisation chimique a révélé la forte présence des coumarines et d’anthocyanes mais seulement des traces de saponosides dans les feuilles de C. procera. Cependant elle n’a pas révélé la présence d’autres groupes particulièrement ichtyotoxiques. Les résultats ont notamment montré qu’avec les macérés aqueux de feuilles fraîches du pommier de Sodome du Sénégal, il faut une concentration de 10000 mg/l pour que 50% des poissons meurent en 4 heures 10 mn et 100% meurent en 5 heures 59 mn. Avec le tourteau de graines de thé, 50% de morts des poissons sont obtenus en 2 heures 37 mn et 100% de morts en 3 heures 23 mn avec la concentration de 25 mg/l. Ceci pourrait expliquer la relative faible ichtyotoxicité des macérés aqueux de feuilles du pommier de Sodome du Sénégal comparée à celle du tourteau de thé.Mots clés : Feuilles de Calotropis procera, ichtyotoxicité, tourteau, graines Camellia sp, tilapia du Nile d’élevage

Internal transcribed spacer sequences analysis of genetic variation among and within populations of Atriplex halimus from different bioclimatic zones in Morocco

The genetic diversity of 12 Atriplex halimus L. populations collected throughout its natural range in Morocco has been studied by using sequences of nrDNA ITS region. Within-population genetic diversity was high in comparison to others species with similar life histories and ecological traits. Most of genetic variation detected by AMOVA resided within populations (94%), relative to the amount of variation among populations (6%). The level of populations differentiation (FST = 0.06) was low, which corresponds with the high level of gene flow (4.00) revealed between populations. Differentiation among ecological groups of populations accounted only for 1.23% of the total ITS variation, which indicates that climatic conditions did not have an effect of population's structuration or that this differentiation is obviously not related to ITS markers. Furthermore, very low genetic differentiation (FCT = 0.015) was observed between regions (Moroccan populations versus American population). Strangely enough, geographic distances were not correlated to genetic differentiation between the populations (r = 0.06, P = 0.5). The structuration of populations in five groups was not operated according to their bioclimatic type. The data obtained in this assay could play a crucial role to establish efficient strategies for genetic resources conservation and to work out the scheme of breeding programs of Atriplex

A framework for estimating society’s economic welfare following the introduction of an animal disease: the case of Johne’s disease

Animal diseases are global issues affecting the productivity and financial profitability of affected farms. Johne’s disease is distributed on farms worldwide and is an endemic contagious bacterial infection in ruminants caused by Mycobacterium avium subspecies paratuberculosis. In cattle, the clinical disease manifests itself as chronic enteritis resulting in reduced production, weight loss, and eventually death. Johne’s disease is prevalent in the UK, including Scotland. Direct costs and losses associated with Johne’s disease have been estimated in previous research, confirming an important economic impact of the disease in UK herds. Despite this, the distributional impact of Johne’s disease among milk consumers and producers in Scotland has not been estimated. In this paper, we evaluate the change in society’s economic welfare, namely to dairy producers (i.e. infected and uninfected herds) and milk consumers in Scotland induced by the introduction of Johne’s disease in the national Scottish dairy herd. At the national-level, we conclude that the economic burden falls mainly on producers of infected herds and, to a lesser extent, milk consumers, while producers of uninfected herds benefit from the presence of Johne’s. An infected producer’s loss per cow is approximately two times larger in magnitude than that of an uninfected producer’s gain. Such economic welfare estimates are an important comparison of the relative costs of national herd prevalence and the wider economic welfare implications for both producers and consumers. This is particularly important from a policy, public good, cost sharing, and human health perspective. The economic welfare framework presented in this paper can be applied to other diseases to examine the relative burden of society’s economic welfare of alternative livestock disease scenarios. In addition, the sensitivity analysis evaluates uncertainty in economic welfare given limited data and uncertainty in the national herd prevalence, and other input parameters, associated with Johne’s disease in Scotland. Therefore, until the prevalence of Johne’s is better understood, the full economic cost to Scottish dairy herds remains uncertain but in the meantime the sensitivity analysis evaluates the robustness of economic welfare to such uncertainties

Preparation of polarization entangled mixed states of two photons

We propose a scheme for preparing arbitrary two photons polarization entangled mixed states via controlled location decoherence. The scheme uses only linear optical devices and single-mode optical fibers, and may be feasible in experiment within current optical technology.Comment: 3 pages, 5 figs. The article has been rewritten. Discussion about experiment are added. To appear in Phys. Rev.

A possible Reinterpretation of Einstein's Equations

In this paper, we first review Huei's formulation in which it is shown that the linearized Einstein equations can be written in the same form as the Maxwell equations. We eliminate some imperfections like the scalar potential which is ill linked to the electric-type field, the Lorentz-type force which is obtained with a time independence restriction and the undesired factor 4 which appears in the magnetic-type part. Second, from these results and in the light of a recent work by C.C. Barros, we propose an extension of the equivalence principle and we suggest a new interpretation for Einstein's equations by showing that the electromagnetic Maxwell equations can be derived from a new version of Einstein's ones.Comment: 11 pages, no figure