A Mid-Infrared Galaxy Atlas (MIGA)

A mid-infrared atlas of part of the Galactic plane ($75^\circ < l < 148^\circ, b = \pm6^\circ$) has been constructed using HIRES processed infrared data to provide a mid-infrared data set for the Canadian Galactic Plane Survey (CGPS). The addition of this data set to the CGPS will enable the study of the emission from the smallest components of interstellar dust at an angular resolution comparable to that of the radio, millimetre, and far-infrared data in the CGPS. The Mid-Infrared Galaxy Atlas (MIGA) is a mid-infrared (12 $\mu$m and 25 $\mu$m) counterpart to the far-infrared IRAS Galaxy Atlas (IGA), and consists of resolution enhanced ($\sim 0.5'$ resolution) HIRES images along with ancillary maps. This paper describes the processing and characteristics of the atlas, the cross-beam simulation technique used to obtain high-resolution ratio maps, and future plans to extend both the IGA and MIGA.Comment: 38 pages (including 15 tables), 13 figures (8 dithered GIF and 5 EPS). Submitted to Astrophysical Journal Supplement Series. A preprint with higher resolution figures is available at http://www.cita.utoronto.ca/~kerton/publications.htm

The resurrection of group selection as a theory of human cooperation

Two books edited by members of the MacArthur Norms and Preferences Network (an interdisciplinary group, mainly anthropologists and economists) are reviewed here. These books in large part reflect a renewed interest in group selection that has occurred among these researchers: they promote the theory that human cooperative behavior evolved via selective processes which favored biological and/or cultural group-level adaptations as opposed to individual-level adaptations. In support of this theory, an impressive collection of cross-cultural data are presented which suggest that participants in experimental economic games often do not behave as self-interested income maximizers; this lack of self-interest is regarded as evidence of group selection. In this review, problems with these data and with the theory are discussed. On the data side, it is argued that even if a behavior seems individually-maladaptive in a game context, there is no reason to believe that it would have been that way in ancestral contexts, since the environments of experimental games do not at all resemble those in which ancestral humans would have interacted cooperatively. And on the theory side, it is argued that it is premature to invoke group selection in order to explain human cooperation, because more parsimonious individual-level theories have not yet been exhausted. In summary, these books represent ambitious interdisciplinary contributions on an important topic, and they include unique and useful data; however, they do not make a convincing case that the evolution of human cooperation required group selection

Recent atmospheric neutrino results from Soudan 2

An updated measurement of the atmospheric nu_mu/nu_e ratio-of-ratios, 0.68+-0.11+-0.06, has been obtained using a 4.6-kty exposure of the Soudan-2 iron tracking calorimeter. The L/E distributions have been analyzed for effects of nu_mu -> nu_x oscillations, and an allowed region in the Delta m^2 vs. sin^2 2 theta plane has been determined.Comment: 3 pages, 4 figures; presented at TAUP99, the 6th Int. Workshop on Topics in Astroparticle and Underground Physics, Sept. 6-10, 1999, College de France, Paris, Franc

Quantum Hall Fluids on the Haldane Sphere: A Diffusion Monte Carlo Study

A generalized diffusion Monte Carlo method for solving the many-body Schr\"odinger equation on curved manifolds is introduced and used to perform a `fixed-phase' simulation of the fractional quantum Hall effect on the Haldane sphere. This new method is used to study the effect of Landau level mixing on the $\nu=1/3$ energy gap and the relative stability of spin-polarized and spin-reversed quasielectron excitations.Comment: 13 pages, Revtex + psfig, figures include

Hubble Space Telescope and Ground-Based Optical and Ultraviolet Observations of GRB010222

We report on Hubble Space Telescope WFPC2 optical and STIS near ultraviolet MAMA observations, and ground-based optical observations of GRB010222, spanning 15 hrs to 71 days. The observations are well-described by a relativistic blast-wave model with a hard electron-energy distribution, p = 1.57, and a jet transition at t_j=0.93 days. These values are slightly larger than previously found as a result of a correction for the contribution from the host galaxy to the late-time ground-based observations and the larger temporal baseline provided by the Hubble Space Telescope observations. The host galaxy is found to contain a very compact core (size <0.25 arcsec) which coincides with the position of the optical transient. The STIS near ultraviolet MAMA observations allow for an investigation of the extinction properties along the line of sight to GRB010222. We find that the far ultraviolet curvature component (c_4) is rather large. In combination with the low optical extinction A_V =0.11 mag, when compared to the Hydrogen column inferred from X-ray observations, we suggest that this is evidence for dust destruction.Comment: ApJ, in pres

Applications of satellite technology to broadband ISDN networks

Two satellite architectures for delivering broadband integrated services digital network (B-ISDN) service are evaluated. The first is assumed integral to an existing terrestrial network, and provides complementary services such as interconnects to remote nodes as well as high-rate multicast and broadcast service. The interconnects are at a 155 Mbs rate and are shown as being met with a nonregenerative multibeam satellite having 10-1.5 degree spots. The second satellite architecture focuses on providing private B-ISDN networks as well as acting as a gateway to the public network. This is conceived as being provided by a regenerative multibeam satellite with on-board ATM (asynchronous transfer mode) processing payload. With up to 800 Mbs offered, higher satellite EIRP is required. This is accomplished with 12-0.4 degree hopping beams, covering a total of 110 dwell positions. It is estimated the space segment capital cost for architecture one would be about $190M whereas the second architecture would be about$250M. The net user cost is given for a variety of scenarios, but the cost for 155 Mbs services is shown to be about $15-22/minute for 25 percent system utilization

Domain Wall Spin Dynamics in Kagome Antiferromagnets

We report magnetization and neutron scattering measurements down to 60 mK on a new family of Fe based kagome antiferromagnets, in which a strong local spin anisotropy combined with a low exchange path network connectivity lead to domain walls intersecting the kagome planes through strings of free spins. These produce unfamiliar slow spin dynamics in the ordered phase, evolving from exchange-released spin-flips towards a cooperative behavior on decreasing the temperature, probably due to the onset of long-range dipolar interaction. A domain structure of independent magnetic grains is obtained that could be generic to other frustrated magnets.Comment: 5 pages, 4 figure

Multi-objective engineering shape optimization using differential evolution interfaced to the Nimrod/O tool

This paper presents an enhancement of the Nimrod/O optimization tool by interfacing DEMO, an external multiobjective optimization algorithm. DEMO is a variant of differential evolution – an algorithm that has attained much popularity in the research community, and this work represents the first time that true multiobjective optimizations have been performed with Nimrod/O. A modification to the DEMO code enables multiple objectives to be evaluated concurrently. With Nimrod/O’s support for parallelism, this can reduce the wall-clock time significantly for compute intensive objective function evaluations. We describe the usage and implementation of the interface and present two optimizations. The first is a two objective mathematical function in which the Pareto front is successfully found after only 30 generations. The second test case is the three-objective shape optimization of a rib-reinforced wall bracket using the Finite Element software, Code_Aster. The interfacing of the already successful packages of Nimrod/O and DEMO yields a solution that we believe can benefit a wide community, both industrial and academic