Chandra view of Kes 79: a nearly isothermal SNR with rich spatial structure

A 30 ks \chandra ACIS-I observation of Kes 79 reveals rich spatial structures, including many filaments, three partial shells, a loop and a ``protrusion''. Most of them have corresponding radio features. Regardless of the different results from two non-equilibrium ionization (NEI) codes, temperatures of different parts of the remnant are all around 0.7 keV, which is surprisingly constant for a remnant with such rich structure. If thermal conduction is responsible for smoothing the temperature gradient, a lower limit on the thermal conductivity of $\sim$ 1/10 of the Spitzer value can be derived. Thus, thermal conduction may play an important role in the evolution of at least some SNRs. No spectral signature of the ejecta is found, which suggests the ejecta material has been well mixed with the ambient medium. From the morphology and the spectral properties, we suggest the bright inner shell is a wind-driven shell (WDS) overtaken by the blast wave (the outer shell) and estimate the age of the remnant to be $\sim$ 6 kyr for the assumed dynamics. Projection is also required to explain the complicated morphology of Kes 79.Comment: 12 pages, 6 figures (3 in color), ApJ, in press, April 20, 200

Star clusters and the structure of the ISM. Tunnels and wakes in giant extragalactic HII regions

Several structures have been discovered embedded in regions of recent or ongoing star formation, which point to the importance of the interaction between fast moving wind-blowing stars and their environment. Using hydrodynamic simulations, we investigate the passage through the interstellar medium of a supersonic stellar wind source, and show how it can naturally lead to the formation of tubes, channels and swamps of globules as interfaces are crossed. The results are in excellent agreement with observation of 30 Doradus.Comment: 12 pages + 5 figures (GIF format) - Accepted for pub. in Astrophys. J. Letter

Decision Analysis Using Value-Focused Thinking for Infrastructure Prioritization

Infrastructure systems and facilities have deteriorated due to the impact of limited defense funding and competing priorities within the Air Force. The current method used for infrastructure prioritization is influenced by political sensitivity and uncertainty regarding the consequences of various funding decisions. Senior leaders need to better understand how their funding decisions will impact the overall condition and service life of the installation\u27s infrastructure systems and facilities. The purpose of this research was to improve the method of prioritizing infrastructure projects through the use of a decision analysis methodology known as Value-Focused Thinking. The value model was created based on the perspective of the civil engineer with inputs from a proxy decision maker at Headquarters Air Force Materiel Command. The model was used to apply three funding strategies to develop prioritized lists of restoration and modernization projects. It also applies metrics to compare the three funding strategies and their impact to the installation\u27s infrastructure. The resulting model provides insight to the decision maker on which funding strategy is best suited for prioritizing infrastructure projects and how their selection of prioritized projects will impact the overall condition and service life of infrastructure systems and facilities

Applications of Wavelets to the Analysis of Cosmic Microwave Background Maps

We consider wavelets as a tool to perform a variety of tasks in the context of analyzing cosmic microwave background (CMB) maps. Using Spherical Haar Wavelets we define a position and angular-scale-dependent measure of power that can be used to assess the existence of spatial structure. We apply planar Daubechies wavelets for the identification and removal of points sources from small sections of sky maps. Our technique can successfully identify virtually all point sources which are above 3 sigma and more than 80% of those above 1 sigma. We discuss the trade-offs between the levels of correct and false detections. We denoise and compress a 100,000 pixel CMB map by a factor of about 10 in 5 seconds achieving a noise reduction of about 35%. In contrast to Wiener filtering the compression process is model independent and very fast. We discuss the usefulness of wavelets for power spectrum and cosmological parameter estimation. We conclude that at present wavelet functions are most suitable for identifying localized sources.Comment: 10 pages, 6 figures. Submitted to MNRA

La constitucionalización del acceso a la información pública gubernamental en México

[Resumen] El presente trabajo muestra el camino recorrido en México para la consecución de la constitucionalización del derecho de acceso a la información pública gubernamental teniendo como punto de partida la doble faz del mismo, por un lado como facultad de la libertad de expresión y por otro como una obligación inherente a la actividad del estado de publicitarse. De igual manera el trabajo aborda todos aquellos aspectos que la reforma constitucional en México propuso como principios rectores del acceso a la información pública desde la obligación de publicidad hasta toda aquella información que aún y cuando no pudiera estar publicitada si debiera ser del conocimiento público.[Abstract] The herein document shows the overhauling in Mexico of the attainment of the constitutionalization of the governmental public information access law having as starting point its own double sight as authority of expression freedom and as an obligation inherent to the state to be published. In the same way, the document undertakes all those aspects proposed by the constitutional reform as governing principles of the access to public information starting with the publicity obligation and ending with all the information that should be of public knowledge