INPOP08, a 4-D planetary ephemeris: From asteroid and time-scale computations to ESA Mars Express and Venus Express contributions

The latest version of the planetary ephemerides developed at the Paris Observatory and at the Besancon Observatory is presented here. INPOP08 is a 4-dimension ephemeris since it provides to users positions and velocities of planets and the relation between TT and TDB. Investigations leading to improve the modeling of asteroids are described as well as the new sets of observations used for the fit of INPOP08. New observations provided by the European Space Agency (ESA) deduced from the tracking of the Mars Express (MEX) and Venus Express (VEX) missions are presented as well as the normal point deduced from the Cassini mission. We show the huge impact brought by these observations in the fit of INPOP08, especially in terms of Venus, Saturn and Earth-Moon barycenter orbits.Comment: 14 pages. submitted to A&A. accepted in A&

Magnetic susceptibility and specific heat of the spin-1/2 Heisenberg model on the kagome lattice and experimental data on ZnCu3(OH)6Cl2

We compute the magnetic susceptibility and specific heat of the spin-1/2 Heisenberg model on the kagome lattice with high-temperature expansions and exact diagonalizations. We compare the results with the experimental data on ZnCu3(OH)6Cl2 obtained by Helton et al. [Phys. Rev. Lett. 98, 107204 (2007)]. Down to k_BT/J~0.2, our calculations reproduce accurately the experimental susceptibility, with an exchange interaction J~190K and a contribution of 3.7% of weakly interacting impurity spins. The comparison between our calculations of the specific heat and the experiments indicate that the low-temperature entropy (below ~20K) is smaller in ZnCu3(OH)6Cl2 than in the kagome Heisenberg model, a likely signature of other interactions in the system.Comment: Minor revisions in the text and references. To appear in Eur. Phys. J.

Timing mirror structures observed by Cluster with a magnetosheath flow model

The evolution of structures associated with mirror modes during their flow in the Earth's magnetosheath is studied. The fact that the related magnetic fluctuations can take distinct shapes, from deep holes to high peaks, has been assessed in previous works on the observational, modeling and numerical points of view. In this paper we present an analytical model for the flow lines and velocity magnitude inside the magnetosheath. This model is used to interpret almost 10 years of Cluster observations of mirror structures: by back tracking each isolated observation to the shock, the "age", or flow time, of these structures is determined together with the geometry of the shock. Using this flow time the evolutionary path of the structures may be studied with respect to different quantities: the distance to mirror threshold, the amplitude of mirror fluctuations and the skewness of the magnetic amplitude distribution as a marker of the shape of the structures. These behaviours are confronted to numerical simulations which confirm the dynamical perspective gained from the association of the statistical analysis and the analytical model: magnetic peaks are mostly formed just behind the shock and are quickly overwhelmed by magnetic holes as the plasma conditions get more mirror stable. The amplitude of the fluctuations are found to saturate before the skewness vanishes, i.e. when both structures quantitatively balance each other, which typically occurs after a flow time of 100–200 s in the Earth's magnetosheath. Comparison with other astrophysical contexts is discussed

Performance of a cryogenic system prototype for the XENON1T Detector

We have developed an efficient cryogenic system with heat exchange and associated gas purification system, as a prototype for the XENON1T experiment. The XENON1T detector will use about 3 ton of liquid xenon (LXe) at a temperature of 175K as target and detection medium for a dark matter search. In this paper we report results on the cryogenic system performance focusing on the dynamics of the gas circulation-purification through a heated getter, at flow rates above 50 Standard Liter per Minute (SLPM). A maximum flow of 114 SLPM has been achieved, and using two heat exchangers in parallel, a heat exchange efficiency better than 96% has been measured

Laser-plasma harmonics with high-contrast pulses and designed prepulses

One aspect of the complexity of mid- and high-harmonic generation in high-intensity laser-plasma interactions is that nonlinear hydrodynamics is virtually always folded together with the nonlinear optical conversion process. We have partly dissected this issue in picosecond and subpicosecond interactions with preformed plasma gradients, imaging and spectrally resolving low- and mid-order harmonics. We describe spatial breakup of the picosecond beam in preformed plasmas, concomitant broadening and breakup of the harmonic spectrum, presumably through self-phase modulation, together with data on the sensitivity of harmonics production efficiency to the gradient or extent of preformed plasma. Lastly, we show preliminary data of regular Stokes-like and anti-Stokes-like satellites to the harmonics, accompanied by modification of the forward-scattered beam. © 1998 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87448/2/342_1.pd

ОЦІНКА ПРИРОДНО-ЗАПОВІДНОГО ФОНДУ ДУБЕНСЬКОГО РАЙОНУ РІВНЕНСЬКОЇ ОБЛАСТІ

Іn the Dubno district, there are only 62 protected objects, with a total area of 4540.5 hectares, which is 2.3% of the area of the NRF region and 8.2% of the area of objects of local importance. Of these: nature reserves of local importance – 25, natural monuments of local importance – 12 and 2 of national importance, nature reserves – 21, parks-attractions of landscape gardening art of local importance – 2.The results of studies of the analysis of the structure of objects of the NRF of the Dubno district are given, the coefficient of the protected area of the area (percentage of the reserve) is determined, which is 1.4%. The reserve is assessed as low (1 point). The qualitative composition of the NRF of the region was assessed. In the presence of three categories of NRF objects, the qualitative composition is assessed as satisfactory (2 points). The index of the density of NRF objects on the territory of the district was determined – 1.9 objects per 100 km2 , which is significantly higher than the average for Ukraine (1.08). The characterization and assessment of the state of wildlife sanctuaries and natural monuments of local importance, nature reserves of the Dubno region are given.To preserve biodiversity and optimize the state of the nature reserve fund of the Dubno region, we suggested paying more attention to the popularization of the reserve management in the region, to form the ecological culture and consciousness of the population by organizing scientific, practical, and environmental measures; increase funding for institutions in charge of natural monuments to improve their condition (for a bequeathed tree, for example, filling cracks, building fences, installing supports for emergency skeletal branches, etc.). It is proposed to lay and arrange tourist, ecologically educational and educational routes, ecological paths.У Дубенському районі нараховується всього 62 заповідних об’єкти загальною площею 4540,5 га, що становить 2,3% від площі ПЗФ області та 8,2% від площі об’єктів місцевого значення. Із них: заказників місцевого значення – 25, пам’яток природи місцевого значення – 12 та 2 загальнодержавного значення, заповідних урочищ – 21, парки-пам’ятки садово-паркового мистецтва місцевого значення – 2.Наведено результати досліджень структури об’єктів ПЗФ Дубенського району, визначено коефіцієнти заповідності та оцінено якісний склад ПЗФ району; визначено показник щільності об’єктів ПЗФ на території Дубенського району; наведено характеристику та здійснено оцінку стану заказників та пам’яток природи місцевого значення, заповідних урочищ Дубенського району. Запропоновані рекомендації щодо збереження заповідних територій та їх біорізноманіття