High Resolution BIMA Observations of CO, HCN, and 13CO in NGC 1068

We present high-resolution CO, HCN, and 13CO maps of the inner arcminute of NGC 1068 made with the BIMA interferometer. Several features appear in the CO map which have not previously been observed: (1) a firm detection of CO line emission from a compact region centered on the nucleus of the galaxy; (2) the detection of a triplet velocity structure characteristic of kinematically independent regions shown on the spectrum of the unresolved nuclear emission ; and (3) the detection of a molecular bar, the extent and position angle of which are in good agreement with the 2 $\mu$m stellar bar. The most intense CO emission is nonnuclear; the structure and kinematics of this emission imply that this gas is distributed along the inner spiral arms and not in a ring. The bar's kinematic influence on the molecular gas in the spiral arms is modest, with typical ordered noncircular motions of \la\ 30 \kms\ in the plane of the galaxy. Interior to the spiral arms, the bar's influence is more dramatic, as reflected by the twisted isovelocity contours in the CO and HCN velocity fields. The surface density of molecular gas within the central 100 pc radius of NGC 1068 is the same as that in the central 200 pc radius in the Milky Way to within the uncertainties. There is evidence for an $m= 1$ kinematic mode in NGC 1068; we find the kinematic center of rotation to be displaced from the radio continuum center by about 2.9", or 200 pc. The HCN image, in contrast to the CO map, shows a strong concentration of emission centered on the nucleus. The ratio of integrated intensities of the HCN emission to that of CO is about 0.6 and is the highest ratio measured in the central region of any galaxy.Comment: 35 pages of uuencoded, compressed postscript, 20 postscript figures not included but available from [email protected] or from ftp://astro.astro.umd.edu/pub/thelfer/n1068_figs.ps.Z To appear in The Astrophysical Journal, V. 450, Sept. 199

Dense Gas in the Milky Way

We present a study of dense gas emission in the Milky Way in order to serve as a basis for comparison with extragalactic results. This study combines new observations of HCN, CS, and CO in individual GMCs and in the Milky Way plane with published studies of emission from these molecules in the inner 500 pc of the Milky Way. We find a strong trend in the fraction of emission from dense gas tracers as a function of location in the Milky Way: in the bulge, I_{HCN}/I_{CO} = 0.081 \pm 0.004, in the plane, I_{HCN}/I_{CO} = 0.026 \pm 0.008 on average, and over the full extent of nearby GMCs, I_{HCN}/I_{CO} = 0.014 \pm 0.020. Similar trends are seen in I_{CS}/I_{CO}. The low intensities of the HCN and CS emission in the plane suggests that these lines are produced by gas at moderate densities; they are thus not like the emission produced by the dense, pc-scale star forming cores in nearby GMCs. The contrast between the bulge and disk ratios in the Milky Way is likely to be caused by a combination of higher kinetic temperatures as well as a higher dense gas fraction in the bulge of the Milky Way.Comment: 34 pages LaTeX, AASTEX macros, includes 11 postscript figures. To appear in ApJ 478, March 199

Backlash Against International Courts in West, East and Southern Africa: Causes and Consequences

This paper discusses three credible attempts by African governments to restrict the jurisdiction of three similarly-situated sub-regional courts in response to politically controversial rulings. In West Africa, when the ECOWAS Court upheld allegations of torture by opposition journalists in the Gambia, that country’s political leaders sought to restrict the Court’s power to review human rights complaints. The other member states ultimately defeated the Gambia’s proposal. In East Africa, Kenya failed in its efforts to eliminate the EACJ and to remove some of its judges after a decision challenging an election to a sub-regional legislature. However, the member states agreed to restructure the EACJ in ways that have significantly affected the court’s subsequent trajectory. In Southern Africa, after the SADC Tribunal ruled in favor of white farmers in disputes over land seizure, Zimbabwe prevailed upon SADC member states to suspend the Tribunal and strip its power to review complaints from private litigants. Variations in the mobilization efforts of Community secretariats, civil society groups and sub-regional Parliaments explain why efforts to eliminate the three courts or narrow their jurisdiction were defeated in ECOWAS, scaled back in the EAC, and largely succeeded in SADC

Counting cycles in labeled graphs: The nonpositive immersion property for one-relator groups

We prove a rank 1 version of the Hanna Neumann Theorem. This shows that every one-relator 2-complex without torsion has the nonpositive immersion property. The proof generalizes to staggered and reducible 2-complexes.Comment: 12 pages, 2 figure

Moving Mirrors and Thermodynamic Paradoxes

Quantum fields responding to "moving mirrors" have been predicted to give rise to thermodynamic paradoxes. I show that the assumption in such work that the mirror can be treated as an external field is invalid: the exotic energy-transfer effects necessary to the paradoxes are well below the scales at which the model is credible. For a first-quantized point-particle mirror, it appears that exotic energy-transfers are lost in the quantum uncertainty in the mirror's state. An accurate accounting of these energies will require a model which recognizes the mirror's finite reflectivity, and almost certainly a model which allows for the excitation of internal mirror modes, that is, a second-quantized model.Comment: 7 pages, Revtex with Latex2

Insertion reliability studies for the RBC-type control rods in ASTRID

International audienceThis paper reports on preliminary studies performed regarding the insertion reliability of theRBC-type Control Rods designed for the ASTRID Sodium-cooled Fast Reactor. At this stage, the primary aim of the analysis is to evaluate the mechanical behavior of RBC Control Rods under Emergency Shutdown conditions, for which reactor core structures are subjected to significant misalignments (including earthquakeimposed displacements). Using a Finite Element Model based on the Cast3M solver and developed specifically for these studies, computations are performed that allow assessing contact reactions (and the associated friction forces and contact pressures), deformations and stresses (mostly due to bending-induced deformations) which are considered for design. Based on these preliminary results, some optimization of the Control Rod design is proposed that ensures some stable behavior all along the rod drop, with substantial design margin