Point vortices on the sphere: a case with opposite vorticities

We study systems formed of 2N point vortices on a sphere with N vortices of strength +1 and N vortices of strength -1. In this case, the Hamiltonian is conserved by the symmetry which exchanges the positive vortices with the negative vortices. We prove the existence of some fixed and relative equilibria, and then study their stability with the ``Energy Momentum Method''. Most of the results obtained are nonlinear stability results. To end, some bifurcations are described.Comment: 35 pages, 9 figure

Focal Plane Detector System of SHARAQ Spectrometer

International audienceThis report describes the basic performance of the detector system installed in the final momentum-dispersive focal plane of the SHARAQ spectrometer

Experimental investigation of the 30S(α, p) thermonuclear reaction in x-ray bursts

We performed the first measurement of 30 S+α resonant elastic scattering to experimentally examine the 30 S(α, p) stellar reaction rate in type I x-ray bursts. These bursts are the most frequent thermonuclear explosions in the galaxy, resulting from thermonuclear runaway on the surface of accreting neutron star binaries. The 30 S(α, p) reaction plays a critical role in burst models, yet very little is known about the compound nucleus 34 Ar at these energies nor the reaction rate itself. We performed a measurement of alpha elastic scattering with a radioactive beam of 30 S to experimentally probe the entrance channel. Utilizing a gaseous active target system and silicon detector array, we extracted the excitation function from 1.8 to 5.5 MeV near 160° in the center-of-mass frame. The experimental data were analyzed with an R -Matrix calculation, and we discovered several new resonances and extracted their quantum properties (resonance energy, width, spin, and parity). Finally, we calculated the narrow resonant thermonuclear reaction rate of 30 S(α, p) for these new resonances

SHARAQ Project: Progress in 2009

On March 23, 2009, the first beam was successfullytransported to the final focal plane of the SHARAQspectrometer. We investigated detector responses toheavy-ion beams and the ion optical properties ofthe SHARAQ spectrometer1) and the high-resolutionbeam line2) in the subsequent commissioning runs andfound that the system as a whole worked almost as perits design. The first physics run with the spectrometerwas performed in November 2009. In this article, wereview the progress in the SHARAQ project in 2009

Asteroids. From Observations to Models

We will discuss some specific applications to the rotation state and the shapes of moderately large asteroids, and techniques of observations putting some emphasis on the HST/FGS instrument.Comment: to appear in LNP; 28pages; written in 2003; Winter School "Dynamique des Corps Celestes Non Ponctuels et des Anneaux", Lanslevillard (FRANCE

Surfactant protein B gene variations enhance susceptibility to squamous cell carcinoma of the lung in German patients

Genetic factors are thought to influence the risk for lung cancer. Since pulmonary surfactant mediates the response to inhaled carcinogenic substances, candidate genes may be among those coding for pulmonary surfactant proteins. In the present matched case–control study a polymorphism within intron 4 of the gene coding for surfactant specific protein B was analysed in 357 individuals. They were divided into 117 patients with lung cancer (40 patients with small cell lung cancer, 77 patients with non small cell lung cancer), matched controls and 123 healthy individuals. Surfactant protein B gene variants were analysed using specific PCR and cloned surfactant protein B sequences as controls. The frequency of the intron 4 variation was similar in both control groups (13.0% and 9.4%), whereas it was increased in the small cell lung cancer group (17.5%) and the non small cell lung cancer group (16.9%). The gene variation was found significantly more frequently in patients with squamous cell carcinoma (25.0%, P=0.016, odds ratio=3.2, 95%CI=1.24–8.28) than in the controls. These results indicate an association of the surfactant protein B intron 4 variants and/or its flanking loci with mechanisms that may enhance lung cancer susceptibility, especially to squamous cell carcinoma of the lung