Degradation of sugar colourants by the white rot fungus Phanerochaete chrysosporium

Colour in sugar industry consists in a complex mixture of different types of colouranfs . The most important being: (1) phenolic compounds coming from the cane plant, (2) caramels which are produced by thermal degradation and condensation reactions of sugars and (3) melanoidins formed from sugar-amino acid reactions via the Maillard reaction. During refining process colourants are removed, at least in part, from the "Iugar liquor by anion-exchange resins. The regeneration of the resins produces an effluent containing those colourants. In order to study the ability of P. chrysosporium to degrade each family of colourant, different culture media specifically enriched with each colourant type were assayed. The results showed that the organism was able to degrade all kinds of tested colourants

A Curvature Principle for the interaction between universes

We propose a Curvature Principle to describe the dynamics of interacting universes in a multi-universe scenario and show, in the context of a simplified model, how interaction drives the cosmological constant of one of the universes toward a vanishingly small value. We also conjecture on how the proposed Curvature Principle suggests a solution for the entropy paradox of a universe where the cosmological constant vanishes.Comment: Essay selected for an honorable mention by the Gravity Research Foundation, 2007. Plain latex, 8 page

Envisioning innovative groundwater management policies through scenario workshops in France and Portugal

International audienceIn the Mediterranean basin, climate change is expected to result in reduced available water resources and increased water demand. This will lead to growing competition for the access to scarce water resources. And it will increase environmental pressures exerted on aquatic ecosystems and problems of water resources overexploitation. Groundwater resources could be significantly affected (drop in water tables, sea water intrusion) in particular because their exploitation is often weakly regulated. In this context, policy makers are increasingly enjoined to explore how current groundwater management rules can be adapted. Given the magnitude of predicted hydro-climatic changes, deep institutional, economic and legal changes will be required to take up the challenge of climate change. Policy makers and stakeholders will have to invent a new water management paradigm, calling into question some of the established assumptions, social values and even ideologies. In particular, the role of the State, market forces and collective action in water management will need to be re-examined. In this paper, we argue that the exploration of possible futures should not be conducted by policy makers and experts alone but that it should also involve grass root water users, farmers in particular. We present a participatory foresight methodology which was implemented in two case studies in southern France (Roussillon) and Portugal (Algarve). After describing the methodology, the paper focuses on three contrasted water management scenarios which were discussed with five groups of farmers. It then describes the results obtained, both in terms of ideas related to future water management scenarios and in terms of participatory process

Aspects of thermal leptogenesis in braneworld cosmology

The mechanism of thermal leptogenesis is investigated in the high-energy regime of braneworld cosmology. Within the simplest seesaw framework with hierarchical heavy Majorana neutrinos, we study the implications of the modified Friedmann equation on the realization of this mechanism. In contrast with the usual leptogenesis scenario of standard cosmology, where low-energy neutrino data favors a mildly strong washout regime, we find that leptogenesis in the braneworld regime is successfully realized in a weak washout regime. Furthermore, a quasi-degenerate light neutrino mass spectrum is found to be compatible with this scenario. For an initially vanishing heavy Majorana neutrino abundance, thermal leptogenesis in the brane requires the decaying heavy Majorana neutrino mass to be M1 > 10^10 GeV and the fundamental five-dimensional gravity scale 10^12 < M5 < 10^16 GeV, which corresponds to a transition from brane to standard cosmology at temperatures 10^8 < Tt < 10^14 GeV.Comment: 7 pages, 3 figures, a few comments and references added. Final version to appear in Phys. Rev.

Instabilities in neutrino-plasma density waves

One examines the interaction and possible resonances between supernova neutrinos and electron plasma waves. The neutrino phase space distribution and its boundary regions are analyzed in detail. It is shown that the boundary regions are too wide to produce non-linear resonant effects. The growth or damping rates induced by neutrinos are always proportional to the neutrino flux and $G_{{\rm F}}^{2}$.Comment: 9 pages, a few words modified to match PRD publicatio

Neutrino helicity asymmetries in leptogenesis

It is pointed out that the heavy singlet neutrinos characteristic of leptogenesis develop asymmetries in the abundances of the two helicity states as a result of the same mechanism that generates asymmetries in the standard lepton sector. Neutrinos and standard leptons interchange asymmetries in collisions with each other. It is shown that an appropriate quantum number, B-L', combining baryon, lepton and neutrino asymmetries, is not violated as fast as the standard B-L. This suppresses the washout effects relevant for the derivation of the final baryon asymmetry. One presents detailed calculations for the period of neutrino thermal production in the framework of the singlet seesaw mechanism.Comment: 11 pages, 1 figure, revtex, matches PRD versio

Role of Modified Chaplygin Gas as a Dark Energy Model in Collapsing Spherically Symmetric Cloud

In this work, gravitational collapse of a spherical cloud, consists of both dark matter and dark energy in the form of modified Chaplygin gas is studied. It is found that dark energy alone in the form of modified Chaplygin gas forms black hole. Also when both components of the fluid are present then the collapse favors the formation of black hole in cases the dark energy dominates over dark matter. The conclusion is totally opposite to the usually known results.Comment: 7 Latex Pages, RexTex style, No figure