Vacuum fluctuations in a supersymmetric model in FRW spacetime

We study a noninteracting supersymmetric model in an expanding FRW spacetime. A soft supersymmetry breaking induces a nonzero contribution to the vacuum energy density. A short distance cutoff of the order of Planck length provides a scale for the vacuum energy density comparable with the observed cosmological constant. Assuming the presence of a dark energy substance in addition to the vacuum fluctuations of the field an effective equation of state is derived in a selfconsistent approach. The effective equation of state is sensitive to the choice of the cut-off but no fine tuning is needed.Comment: 19 pages, accepted for publication in Phys. Rev.

Implications of Weak-Interaction Space Deformation for Neutrino Mass Measurements

The negative values for the squares of both electron and muon neutrino masses obtained in recent experiments are explained as a possible consequence of a change in metric within the weak-interaction volume in the energy-momentum representation. Using a model inspired by a combination of the general theory of relativity and the theory of deformation for continuous media, it is shown that the negative value of the square of the neutrino mass can be obtained without violating allowed physical limits. The consequence is that the negative value is not necessary unphysical.Comment: 12 pages, 5 figures, LaTe

Merger Control Procedures and Institutions: A Comparison of the EU and US Practice

The objective of this paper is to discuss and compare the role that different constituencies play in US and EU procedures for merger control. We describe the main constituencies (both internal and external) involved in merger control in both jurisdictions and discuss how a typical merger case would be handled under these procedures. At each stage, we consider how the procedure unfolds, which parties are involved, and how they can affect the procedure. Our discussion reveals a very different ecology. EU and US procedures differ in terms of their basic design and in terms of the procedures that are naturally associated with these alternative designs. On the one hand, there is a single investigator and decision maker operating under a symmetric mandate in the EU and on the other hand, an investigation and settlement operating under the threat of a court decision in case of challenge only in the US. The EU has developed numerous procedures and has granted extensive rights to the parties in the context of these procedures in order to provide some guarantee that the Commission’s role as investigator and decision maker at first instance is not abused. By contrast, the US procedures appear to be rather informal, the balance in the investigation and evaluation of the merger being provided by the credible threat of a court decision. With a strong federal government that has extensive competences for regulation, merger control on competition grounds is subject to the additional public interest test of regulators in the US. Such additional control is weak in the EU, which has more limited competences for regulation. In addition, both the executive and the legislative powers are more fully developed at the federal level in the US. Both the executive power and the legislative seem to be in position to wield greater influence on enforcement in the US than is the case in the EU

Extracellular Nucleotides Regulate Arterial Calcification by Activating Both Independent and Dependent Purinergic Receptor Signaling Pathways

Arterial calcification, the deposition of calcium-phosphate crystals in the extracellular matrix, resembles physiological bone mineralization. It is well-known that extracellular nucleotides regulate bone homeostasis raising an emerging interest in the role of these molecules on arterial calcification. The purinergic independent pathway involves the enzymes ecto-nucleotide pyrophosphatase/phosphodiesterases (NPPs), ecto-nucleoside triphosphate diphosphohydrolases (NTPDases), 5′-nucleotidase and alkaline phosphatase. These regulate the production and breakdown of the calcification inhibitor—pyrophosphate and the calcification stimulator—inorganic phosphate, from extracellular nucleotides. Maintaining ecto-nucleotidase activities in a well-defined range is indispensable as enzymatic hyper- and hypo-expression has been linked to arterial calcification. The purinergic signaling dependent pathway focusses on the activation of purinergic receptors (P1, P2X and P2Y) by extracellular nucleotides. These receptors influence arterial calcification by interfering with the key molecular mechanisms underlying this pathology, including the osteogenic switch and apoptosis of vascular cells and possibly, by favoring the phenotypic switch of vascular cells towards an adipogenic phenotype, a recent, novel hypothesis explaining the systemic prevention of arterial calcification. Selective compounds influencing the activity of ecto-nucleotidases and purinergic receptors, have recently been developed to treat arterial calcification. However, adverse side-effects on bone mineralization are possible as these compounds reasonably could interfere with physiological bone mineralization

Experimental evaluation of the generalized vibrational theory of G protein-coupled receptor activation

Herein, we test the present iteration of the vibrational theory of protein activation by comparing predictions obtained from Turin’s vibrational theory for the activation of olfactory receptors measuring affinity and activation at a nonolfactory receptor family of G protein-coupled receptors. This was done at the CNS serotonin receptor family h5-HT2 and with both the 2,5-dimethoxy-4-iodoamphetamine and N,N-dimethyllysergamide agonists. Invalidation was performed through a comparative analysis of agonist behavior between isotopologues

Logics for Unranked Trees: An Overview

Labeled unranked trees are used as a model of XML documents, and logical languages for them have been studied actively over the past several years. Such logics have different purposes: some are better suited for extracting data, some for expressing navigational properties, and some make it easy to relate complex properties of trees to the existence of tree automata for those properties. Furthermore, logics differ significantly in their model-checking properties, their automata models, and their behavior on ordered and unordered trees. In this paper we present a survey of logics for unranked trees

Chaplygin Gas Cosmology - Unification of Dark Matter and Dark Energy

The models that unify dark matter and dark energy based upon the Chaplygin gas fail owing to the suppression of structure formation by the adiabatic speed of sound. Including string theory effects, in particular the Kalb-Ramond field, we show how nonadiabatic perturbations allow a successful structure formation.Comment: 7 pages, presented by N. B. at IRGAC 2006, Barcelona, 11-15 July 2006, typos corrected, concluding paragraph slightly expanded, final version, accepted in J. Phys. A, special issu