IMPACT OF SERVICES ON RURAL COMMUNITIES

Community/Rural/Urban Development,

Mid - infrared interferometry of massive young stellar objects II Evidence for a circumstellar disk surrounding the Kleinmann - Wright object

The formation scenario for massive stars is still under discussion. To further constrain current theories, it is vital to spatially resolve the structures from which material accretes onto massive young stellar objects (MYSOs). Due to the small angular extent of MYSOs, one needs to overcome the limitations of conventional thermal infrared imaging, regarding spatial resolution, in order to get observational access to the inner structure of these objects.We employed mid - infrared interferometry, using the MIDI instrument on the ESO /VLTI, to investigate the Kleinmann - Wright Object, a massive young stellar object previously identified as a Herbig Be star precursor. Dispersed visibility curves in the N- band (8 - 13 {\mu}m) have been obtained at 5 interferometric baselines. We show that the mid - infrared emission region is resolved. A qualitative analysis of the data indicates a non - rotationally symmetric structure, e.g. the projection of an inclined disk. We employed extensive radiative transfer simulations based on spectral energy distribution fitting. Since SED - only fitting usually yields degenerate results, we first employed a statistical analysis of the parameters provided by the radiative transfer models. In addition, we compared the ten best - fitting self - consistent models to the interferometric observations. Our analysis of the Kleinmann - Wright Object suggests the existence of a circumstellar disk of 0.1M\odot at an intermediate inclination of 76\circ, while an additional dusty envelope is not necessary for fitting the data. Furthermore, we demonstrate that the combination of IR interferometry with radiative transfer simulations has the potential to resolve ambiguities arising from the analysis of spectral energy distributions alone.Comment: 12 pages, 22 figures accepted for publication in A&

Squeaky Wheel Optimization

We describe a general approach to optimization which we term `Squeaky Wheel' Optimization (SWO). In SWO, a greedy algorithm is used to construct a solution which is then analyzed to find the trouble spots, i.e., those elements, that, if improved, are likely to improve the objective function score. The results of the analysis are used to generate new priorities that determine the order in which the greedy algorithm constructs the next solution. This Construct/Analyze/Prioritize cycle continues until some limit is reached, or an acceptable solution is found. SWO can be viewed as operating on two search spaces: solutions and prioritizations. Successive solutions are only indirectly related, via the re-prioritization that results from analyzing the prior solution. Similarly, successive prioritizations are generated by constructing and analyzing solutions. This `coupled search' has some interesting properties, which we discuss. We report encouraging experimental results on two domains, scheduling problems that arise in fiber-optic cable manufacturing, and graph coloring problems. The fact that these domains are very different supports our claim that SWO is a general technique for optimization

A stochastic sub-national population projection methodology with an application to the Waikato region of New Zealand

In this paper we use a stochastic population projection methodology at the sub-national level as an alternative to the conventional deterministic cohort-component method. We briefly evaluate the accuracy of previous deterministic projections and find that there is a tendency for these to be conservative: under-projecting fast growing populations and over-projecting slow growing ones. We generate probabilistic population projections for five demographically distinct administrative areas within the Waikato region of New Zealand, namely Hamilton City, Franklin District, Thames-Coromandel District, Otorohanga District and South Waikato District. Although spatial interaction between the areas is not taken into account in the current version of the methodology, a consistent set of cross-regional assumptions is used. The results are compared to official sub-national deterministic projections. The accuracy of sub-national population projections is in New Zealand strongly affected by the instability of migration as a component of population change. Unlike the standard cohort-component methodology, in which net migration levels are projected, the key parameters of our stochastic methodology are age-gender-area specific net migration rates. The projected range of rates of population growth is wider for smaller regions and/or regions more strongly affected by net migration. Generally, the identified and modelled uncertainty makes the traditional ‘mid range’ scenario of sub-national population projections of limited use for policy analysis or planning beyond a relatively short projection horizon. Directions for further development of a stochastic sub-national projection methodology are suggested

Discovery of Gas Bulk Motion in the Galaxy Cluster Abell 2256 with Suzaku

The results from Suzaku observations of the galaxy cluster Abell2256 are presented. This cluster is a prototypical and well-studied merging system, exhibiting substructures both in the X-ray surface brightness and in the radial velocity distribution of member galaxies. There are main and sub components separating by 3'.5 in the sky and by about 2000 km s$^{-1}$ in radial velocity peaks of member galaxies. In order to measure Doppler shifts of iron K-shell lines from the two gas components by the Suzaku XIS, the energy scale of the instrument was evaluated carefully and found to be calibrated well. A significant shift of the radial velocity of the sub component gas with respect to that of the main cluster was detected. All three XIS sensors show the shift independently and consistently among the three. The difference is found to be 1500 $\pm 300$ (statistical) $\pm 300$ (systematic) km s$^{-1}$. The X-ray determined absolute redshifts of and hence the difference between the main and sub components are consistent with those of member galaxies in optical. The observation indicates robustly that the X-ray emitting gas is moving together with galaxies as a substructure within the cluster. These results along with other X-ray observations of gas bulk motions in merging clusters are discussed.Comment: Accepted for publication in PASJ in 2011-03-2