Les contrôles américains sur les exportations stratégiques : historique et évolution

A brief historical survey of the u.s. export controls on strategic goods indicate the importance of the Cold War in achieving these objectives as well as the importance of polycentrism across and within the institutions and agencies concerned. The proliferation of controls has brought about a large area of freedom for the implementation of foreign policy by the executive branch of the Government. After the end of the Cold War, one can surmise that the emphasis mil be felt at three different levels : a greater discretion by national actors in the implementation of export controls policy, a greater harmonization of multilateral efforts designed at promoting the nonproliferation of weapons of mass destruction, and greater cleavages between those who want to relax export controls for economic reasons and those who want to strengthen them for security reasons. On the whole, the multiplicity of legislative actions and organizations concerned can only reinforce the freedom of action of the executive branch of the Government

Statistical mechanics of random graphs

We discuss various aspects of the statistical formulation of the theory of random graphs, with emphasis on results obtained in a series of our recent publications.Comment: 6 pages (Talk at Conference: Applications of Physics in Financial Analysis 4, Warsaw 13-15 Nov. 2003

Temporally resolved second-order photon correlations of exciton-polariton Bose-Einstein condensate formation

Second-order time correlation measurements with a temporal resolution better than 3 ps were performed on a CdTe microcavity where spontaneous Bose-Einstein condensation is observed. After the laser pulse, the nonresonantly excited thermal polariton population relaxes into a coherent polariton condensate. Photon statistics of the light emitted by the microcavity evidences a clear phase transition from the thermal state to a coherent state, which occurs within 3.2 ps after the onset of stimulated scattering. Following this very fast transition, we show that the emission possesses a very high coherence that persists for more than 100 ps after the build-up of the condensate.Comment: 4 pages, 3 figure

Modelling Round-the-Clock Price Discovery for Cross-Listed Stocks using State Space Methods

U.S. trading in non-U.S. stocks has grown dramatically. Round-the-clock, these stocks trade in the home market, in the U.S. market and, potentially, in both markets simultaneously. We develop a general methodology based on a state space model to study 24-hour price discovery in a multiple markets setting. As opposed to the standard variance ratio approach, this model deals naturally with (i) simultaneous quotes in an overlap, (ii) missing observations in a non-overlap, (iii) noise due to transitory microstructure effects, and (iv) contemporaneous correlation in returns due to market-wide factors. We provide an application of our model to Dutch-U.S. stocks. Our findings suggest a minor role for the NYSE in price discovery for Dutch shares, in spite of its non-trivial and growing market share. The results differ significantly from the variance ratio approach

The search for high-energy neutrinos coincident with fast radio bursts with the ANTARES neutrino telescope

In the past decade, a new class of bright transient radio sources with millisecond duration has been discovered. The origin of these so-called fast radio bursts (FRBs) is still a mystery, despite the growing observational efforts made by various multiwavelength and multimessenger facilities. To date, many models have been proposed to explain FRBs, but neither the progenitors nor the radiative and the particle acceleration processes at work have been clearly identified. In this paper, we assess whether hadronic processes may occur in the vicinity of the FRB source. If they do, FRBs may contribute to the high-energy cosmic-ray and neutrino fluxes. A search for these hadronic signatures was carried out using the ANTARES neutrino telescope. The analysis consists in looking for high-energy neutrinos, in the TeV–PeV regime, that are spatially and temporally coincident with the detected FRBs. Most of the FRBs discovered in the period 2013–2017 were in the field of view of the ANTARES detector, which is sensitive mostly to events originating from the Southern hemisphere. From this period, 12 FRBs were selected and no coincident neutrino candidate was observed. Upper limits on the per-burst neutrino fluence were derived using a power-law spectrum, dN/dE¿¿E-¿¿¿, for the incoming neutrino flux, assuming spectral indexes ¿ = 1.0, 2.0, 2.5. Finally, the neutrino energy was constrained by computing the total energy radiated in neutrinos, assuming different distances for the FRBs. Constraints on the neutrino fluence and on the energy released were derived from the associated null resultsPeer ReviewedPostprint (published version

Implementation of LOFAR RFI mitigation strategy

ASTRON is building the world’s largest radio telescope for low frequencies, LOFAR. LOFAR is optimized for detecting astronomical signals in the 30-80 MHz and 120-240 MHz frequency windows. Since this part of the spectrum is in extensive use by others, a special RFI mitigation strategy is implemented which will be described in the paper. International RFI measurements will be presented and we will focus on practical implementation issues such as the impact of Digital Video Broadcast, RF emissions from power lines and the influence of large wind turbines on the EM environmen

The universal non-neuronal nature of parkinson's disease: a theory

Various recent developments of relevance to Parkinson's disease (PD) are discussed and integrated into a comprehensive hypothesis on the nature, origin and inter-cellular mode of propagation of late-onset sporadic PD. We propose to define sporadic PD as a characteristic pathological deviation in the global gene expression program of a cell: the PD expression-state, or PD-state for short. Although a universal cell-generic state, the PD-state deviation would be particularly damaging in a neuronal context, ultimately leading to neuron death and the ensuing observed clinical signs. We review why age accumulated damage caused by oxidative stress in mitochondria could be the trigger for a primordial cell to shift to the PD-state. We put forward hematopoietic cells could be the first to acquire the PD-state, at hematopoiesis, from the disruption in reactive oxygen species (ROS) homeostasis that arises with age in the hematopoietic stem-cell niche. We argue why, nonetheless, such a process is unlikely to explain the shift to the PD-state of all the subsequently affected cells in a patient, thus indicating the existence of a distinct mechanism of propagation of the PD-state. We highlight recent findings on the intercellular exchange of mitochondrial DNA and the ability of mitochondrial DNA to modulate the cellular global gene expression state and propose this could form the basis for the intercellular propagation of the PD-state

Determining the neutrino mass ordering and oscillation parameters with KM3NeT/ORCA

The next generation of water Cherenkov neutrino telescopes in the Mediterranean Sea are under construction offshore France (KM3NeT/ORCA) and Sicily (KM3NeT/ARCA). The KM3NeT/ORCA detector features an energy detection threshold which allows to collect atmospheric neutrinos to study flavour oscillation. This paper reports the KM3NeT/ORCA sensitivity to this phenomenon. The event reconstruction, selection and classification are described. The sensitivity to determine the neutrino mass ordering was evaluated and found to be 4.4s if the true ordering is normal and 2.3s if inverted, after 3 years of data taking. The precision to measure ¿m2 32 and ¿23 were also estimated and found to be 85.10-6 eV2 and ( +1.9 -3.1)¿ for normal neutrino mass ordering and, 75.10-6 eV2 and ( +2.0 -7.0)¿ for inverted ordering. Finally, a unitarity test of the leptonic mixing matrix by measuring the rate of tau neutrinos is described. Three years of data taking were found to be sufficient to exclude ¿t event rate variations larger than 20% at 3s level.Peer ReviewedPostprint (published version

Water stress during reproductive stages affects seed quality and yield of pea (Pisum sativum L)

International audiencePhysiological quality of pea (Pisum sativum L.) seed depends on various factors affecting the plant, including water supply, the effect of which has not been fully characterized. The effects of different periods of water stress during reproductive stages on the seed yield and seed physiological quality were investigated in field studies for 3 yr (1991, 1992, and 1993) at Brain-sur-l'Authion, France, on a Mollisol, Rendoll, eutrochreptic soil. Irrigation during seed filling (IDSF) and irrigation during the period from the start of flowering to the start of seed filling were compared with a non-irrigated (NI) and a season-long, irrigated-as-needed (WI) treatment. The physiological quality of pea seeds was assessed by germination percentage and the conductivity and cold tests. The germination percentage averaged 98% and was not modified by water stress. In 1993, rainfall during the reproductive stages was high, and there were no differences in seed yield or quality between treatments. In 1991 and 1992, the rainfall was much lower, and the NI treatment showed the lowest seed yield and quality as far as the conductivity test and cold test were concerned. The WI treatment showed the best yields. Water stress during the flowering period did not reduce seed quality more than WI, and reduced seed yield only slightly. Water stress during seed filling decreased seed yield but the effect on seed quality was not significant. Individual seed weight was higher and less variable in IDSF treatments than in WI treatments. Changing irrigation strategies for pea seed production by irrigating during seed filling may improve the physiological quality of the seedlots without decreasing the seed yield