Real time plasma equilibrium reconstruction in a Tokamak

The problem of equilibrium of a plasma in a Tokamak is a free boundary problemdescribed by the Grad-Shafranov equation in axisymmetric configurations. The right hand side of this equation is a non linear source, which represents the toroidal component of the plasma current density. This paper deals with the real time identification of this non linear source from experimental measurements. The proposed method is based on a fixed point algorithm, a finite element resolution, a reduced basis method and a least-square optimization formulation

The Ionizing Stars of the Galactic Ultra-Compact HII Region G45.45+0.06

Using the NIFS near-infrared integral-field spectrograph behind the facility adaptive optics module, ALTAIR, on Gemini North, we have identified several massive O-type stars that are responsible for the ionization of the Galactic Ultra-Compact HII region G45.45+0.06. The sources ``m'' and ``n'' from the imaging study of Feldt et a. 1998 are classified as hot, massive O-type stars based on their K-band spectra. Other bright point sources show red and/or nebular spectra and one appears to have cool star features that we suggest are due to a young, low-mass pre-main sequence component. Still two other embedded sources (``k'' and ``o'' from Feldt et al.) exhibit CO bandhead emission that may arise in circumstellar disks which are possibly still accreting. Finally, nebular lines previously identified only in higher excitation planetary nebulae and associated with KrIII and SeIV ions are detected in G45.45+0.06.Comment: Latex, 28 pages, 10 figure

Growth of Dust as the Initial Step Toward Planet Formation

We discuss the results of laboratory measurements and theoretical models concerning the aggregation of dust in protoplanetary disks, as the initial step toward planet formation. Small particles easily stick when they collide and form aggregates with an open, often fractal structure, depending on the growth process. Larger particles are still expected to grow at collision velocities of about 1m/s. Experiments also show that, after an intermezzo of destructive velocities, high collision velocities above 10m/s on porous materials again lead to net growth of the target. Considerations of dust-gas interactions show that collision velocities for particles not too different in surface-to-mass ratio remain limited up to sizes about 1m, and growth seems to be guaranteed to reach these sizes quickly and easily. For meter sizes, coupling to nebula turbulence makes destructive processes more likely. Global aggregation models show that in a turbulent nebula, small particles are swept up too fast to be consistent with observations of disks. An extended phase may therefore exist in the nebula during which the small particle component is kept alive through collisions driven by turbulence which frustrates growth to planetesimals until conditions are more favorable for one or more reasons.Comment: Protostars and Planets V (PPV) review. 18 pages, 5 figure

Calcutation of kaon matrix elements in quenched domain-wall QCD with DBW2 gauge action

We give a progress report of our new $a^{-1}\approx 3$ GeV quenched calculation of kaon matrix elements with domain-wall fermion and DBW2 gauge action. Our smaller lattice spacing allows us to address the effect of charmed quark on the lattice. We show preliminary results of $B_K$ renormalized non-perturbatively and $K\to\pi$ matrix elements.Comment: Lattice2003(matrix), 3 pages, 6 figure

Effect of psychotropic drugs on gastric ulcers induced by immobilization: Increased protective effect of amitriptyline caused by chlordiazepoxide

Amitriptyline, but not chlordiazepoxide, protects rats from the occurrence of gastric erosions and ulcers following immobilization. When, however, chlordiazepoxide is given together with amitriptyline the protective effect of the latter is markedly increased

Study of abrasive techniques for lunar and planetary solid rock geological sampling

Abrasive techniques for lunar and planetary geological samplin

Submillimetre-sized dust aggregate collision and growth properties

The collisional and sticking properties of sub-mm-sized aggregates composed of protoplanetary dust analogue material are measured, including the statistical threshold velocity between sticking and bouncing, their surface energy and tensile strength within aggregate clusters. We performed an experiment on the REXUS 12 suborbital rocket. The protoplanetary dust analogue materials were micrometre-sized monodisperse and polydisperse SiO2 particles prepared into aggregates with sizes around 120 $\mu$m and 330 $\mu$m, respectively and volume filling factors around 0.37. During the experimental run of 150 s under reduced gravity conditions, the sticking of aggregates and the formation and fragmentation of clusters of up to a few millimetres in size was observed. The sticking probability of the sub-mm-sized dust aggregates could be derived for velocities decreasing from 22 to 3 cm/s. The transition from bouncing to sticking collisions happened at 12.7 cm/s for the smaller aggregates composed of monodisperse particles and at 11.5 and 11.7 cm/s for the larger aggregates composed of mono- and polydisperse dust particles, respectively. Using the pull-off force of sub-mm-sized dust aggregates from the clusters, the surface energy of the aggregates composed of monodisperse dust was derived to be 1.6x10-5 J/m2, which can be scaled down to 1.7x10-2 J/m2 for the micrometre-sized monomer particles and is in good agreement with previous measurements for silica particles. The tensile strengths of these aggregates within the clusters were derived to be 1.9 Pa and 1.6 Pa for the small and large dust aggregates, respectively. These values are in good agreement with recent tensile strength measurements for mm-sized silica aggregates. Using our data on the sticking-bouncing threshold, estimates of the maximum aggregate size can be given. For a minimum mass solar nebula model, aggregates can reach sizes of 1 cm.Comment: 21 pages (incl. 6 pages of appendix), 23 figure