410 - Phase transitions induced by coloured voltage noise in nerve membranes

Quantitative conditions are derived under which electrically excitable membranes can undergo a phase transition induced by an externally applied voltage noise. The results obtained for a non-cooperative and a cooperative form of the two-state model are compared. © 1981.

Returns to shareholder activism: Evidence from a clinical study of the hermes UK focus fund

This article reports a unique analysis of private engagements by an activist fund. It is based on data made available to us by Hermes, the fund manager owned by the British Telecom Pension Scheme, on engagements with management in companies targeted by its UK Focus Fund. In contrast with most previous studies of activism, we report that the fund executes shareholder activism predominantly through private interventions that would be unobservable in studies purely relying on public information. The fund substantially outperforms benchmarks and we estimate that abnormal returns are largely associated with engagements rather than stock picking. © The Author 2008.

Incoherent solitons and condensation processes

We show that coherent phase effects may play a relevant role in the nonlinear propagation of partially incoherent waves, which lead to unexpected processes of condensation, or incoherent soliton generation in instantaneous response nonlinear media. © 2005 OSA.

Approximation limits of linear programs (beyond hierarchies)

We develop a framework for proving approximation limits of polynomial size linear programs (LPs) from lower bounds on the nonnegative ranks of suitably defined matrices. This framework yields unconditional impossibility results that are applicable to any LP as opposed to only programs generated by hierarchies. Using our framework, we prove that O(n^1/2-ε)-approximations for CLIQUE require LPs of size 2^nΩ(ε). This lower bound applies to LPs using a certain encoding of CLIQUE as a linear optimization problem. Moreover, we establish a similar result for approximations of semidefinite programs by LPs. Our main technical ingredient is a quantitative improvement of Razborov's [38] rectangle corruption lemma for the high error regime, which gives strong lower bounds on the nonnegative rank of shifts of the unique disjointness matrix.

Actualités thérapeutiques

SCOPUS: sh.j

Clinical practice guideline on diagnosis and treatment of hyponatraemia

Hyponatraemia, defined as a serum sodium concentration <135 mmol/l, is the most common disorder of body fuid and electrolyte balance encountered in clinical practice. It can lead to a wide spectrum of clinical symptoms, from subtle to severe or even life threatening, and is associated with increased mortality, morbidity and length of hospital stay in patients presenting with a range of conditions. Despite this, the management of patients remains problematic. The prevalence of hyponatraemia in widely different conditions and the fact that hyponatraemia is managed by clinicians with a broad variety of backgrounds have fostered diverse institution-and speciality-based approaches to diagnosis and treatment. To obtain a common and holistic view, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE) and the European Renal Association-European Dialysis and Transplant Association (ERA-EDTA), represented by European Renal Best Practice (ERBP), have developed the Clinical Practice Guideline on the diagnostic approach and treatment of hyponatraemia as a joint venture of three societies representing specialists with a natural interest in hyponatraemia. In addition to a rigorous approach to methodology and evaluation, we were keen to ensure that the document focused on patient-important outcomes and included utility for clinicians involved in everyday practice.

On the extension complexity of combinatorial polytopes

In this paper we extend recent results of Fiorini et al. on the extension complexity of the cut polytope and related polyhedra. We first describe a lifting argument to show exponential extension complexity for a number of NP-complete problems including subset-sum and three dimensional matching. We then obtain a relationship between the extension complexity of the cut polytope of a graph and that of its graph minors. Using this we are able to show exponential extension complexity for the cut polytope of a large number of graphs, including those used in quantum information and suspensions of cubic planar graphs.

The Askaryan radio array

The Askar'yan Radio Array (ARA), a neutrino detector to be situated at the South Pole next to the IceCube detector, will be sensitive to ultrahigh-energy cosmic neutrinos above 0.1 EeV and will have the greatest sensitivity within the favored energy range from 0.1 EeV up to 10 EeV. Neutrinos of this energy are guaranteed by current observations of the GZK-cutoff by the HiRes and Pierre Auger Observatories. The detection method is based on Cherenkov emission by a neutrino induced cascade in the ice, coherent at radio wavelengths, which was predicted by Askar'yan in 1962 and verified in beam tests at SLAC in 2006. The detector is planned to consist of 37 stations with 16 antennas each, deployed at depths of up to 200 m under the ice surface. During the last two polar seasons (2010-2011, 2011-2012), a prototype station and a first detector station were successfully deployed and are taking data. These data have been and are currently being analyzed to study the ambient noise background and the radio frequency properties of the South Pole ice sheet. A worldwide collaboration is working on the planning, construction and data analysis of the detector array. This article will give a short report on the status of the ARA detector and show recent results from the recorded data. © 2013 AIP Publishing LLC.

Plasma kinetic theory

Kinetic theory studies the macroscopic properties of large numbers of particles, starting from their (classical) equations of motion while the thermodynamics describes the equilibrium behavior of macroscopic objects in terms of concepts such as work, heat, and entropy. The phenomenological laws of thermodynamics tell us how these quantities are constrained as a system approaches its equilibrium. At the microscopic level, we know that these systems are composed of particles (atoms, particles), whose interactions and dynamics are reasonably well understood in terms of more fundamental theories. If these microscopic descriptions are complete, we should be able to account for the macroscopic behavior, i.e. derive the laws governing the macroscopic state functions in equilibrium. Kinetic theory attempts to achieve this objective. In particular, we shall try to answer the following questions [1]: How can we define equilibrium for a system of moving particles? Do all systems naturally evolve towards an equilibrium state? What is the time evolution of a system that is not quite in equilibrium?

Anomalous transport in plasmas

The application of stochastic methods to the problem of particle and energy transport in turbulent plasmas is briefly reviewed. The "classical" Corrsin approximation is shown to be valid only in the limit of weak turbulence. The recently developed method of decorrelation trajectories is applicable over the whole range of turbulence intensities and yields the correct asymptotic behavior in the limit of very strong turbulence (subdiffusion). © 2004 Wiley Periodicals, Inc.

La place de la chimiothérapie dans le traitement du cancer broncho pulmonaire

Single agent chemotherapy of advanced lung cancer is still unsatisfactory. The most encouraging results have been obtained with high dose intermittent treatment with cyclophosphamide, methotrexate or adriamycin. Combination chemotherapy is probably more efficacious than single agent chemotherapy, especially in oat cell carcinoma. The best treatment schedules give a response rate of approximately 80%. The value of adjuvant chemotherapy is not yet established, but new controlled clinical trials are indicated considering the poor results achieved by surgery and radiotherapy.

On codon usage

SCOPUS: ar.j

Le suivi des anti-épileptiques

All antiepileptic medications have potential side-effects. Some are rather specific like diplopia for carbamazepin or lamotrigin, whereas others are not, like fatigue or unsteadiness. Most are dose- related and can therefore be alleviated by dose reduction (e.g. somnolence or tremor) but a few are idiosyncratic (e.g. rash) and require cessation of the causative agent. Some can be detected and followed-up on a clinical basis but others necessitate specific examinations.