Surface ages of mid-size Saturnian satellites

The observations of the surfaces of the mid sized Saturnian satellites made by Cassini Huygens mission have shown a variety of features that allows study of the processes that took place and are taking place on those worlds. Research of the Saturnian satellite surfaces has clear implications for Saturn history and surroundings. In a recent paper, the production of craters on the mid sized Saturnian satellites by Centaur objects was calculated considering the current Solar System. We have compared our results with crater counts from Cassini images and we have noted that the number of observed small craters is less than our calculated number. In this paper we estimate the age of the surface for each observed terrain on each mid sized satellite of Saturn. We have noticed that since there are less observed small craters than calculated (except on Iapetus), this results in younger ages. This could be the result of efficient endogenous or exogenous process(es) for erasing small craters and or crater saturation at those sizes. The size limit from which the observed number of smaller craters is less than the calculated is different for each satellite, possibly indicating processes that are unique to each, but other potential common explanations would be crater saturation and or deposition of E ring particles. These processes are also suggested by the findings that the smaller craters are being preferentially removed, and the erasure process is gradual. On Enceladus, only mid and high latitude plains have remnants of old terrains; the other regions could be young; the regions near the South Polar Terrain could be as young as 50 Myr old. On the contrary for Iapetus, all the surface is old and it notably registers a primordial source of craters. As the crater size is decreased, it would be perceived to approach saturation until D less than 2 km craters, where saturation is complete.Comment: Accepted for publication in Icarus, 40 pages, 11 figure

Voluntary Environmental Agreements when Regulatory Capacity Is Weak

Voluntary agreements (VAs) negotiated between environmental regulators and industry are increasingly popular. However, little is known about whether they are likely to be effective in developing and transition countries, where local and federal environmental regulatory capacity is typically weak. We develop a dynamic theoretical model to examine the effect of VAs on investment in regulatory infrastructure and pollution abatement in such countries. We find that under certain conditions, VAs can improve welfare by generating more private-sector investment in pollution control and more public-sector investment in regulatory capacity than the status quo.voluntary environmental regulation, developing country

Manejo sustentable del uso de agua y crecimiento urbano

Municipal water utilities face a complex set of environmental, economic, technical and administrative challenges, among others. In Northern Mexico, urban growth in the face of scarce water resources poses a serious sustainability problem. Water demand and supply management in that context could contribute towards improving the balance between extraction and recharge in the water sources exploited by municipal water systems, and thereby the sustainability of municipal water use. This paper evaluates the potential in that respect of two specific management tools: the cost of water for users (for demand control) and the physical efficiency of conveyance and distribution infrastructures (to control the balance between extraction and use). For that purpose, it is established the relationship between population, water use, physical efficiency, administrative efficiency and extraction requirement in a municipal water system; develop a long term extraction requirement forecast procedure that takes into account distinct scenarios with respect to the application of the aforementioned management tools; and, specify these scenarios based on the analysis of technical and financial data from municipal water utilities. It is presented a case study for the Laguna Metropolitan Area however the methodology could be applied to any other region. The results, combined with relevant hydrological information for the case study region, suggest that the application of the management tools could have a significant impact on municipal extraction requirements; however, this would be insufficient in and of itself to attain sustainability. For that, an integrated water resources management approach that considers simultaneously all types of water uses would be necessary.municipal water use, extraction requirement, growth, sustainability, Laguna Metropolitan Area

How Do Canadian Provinces and U.S. States View the Importance of Their Relationship with Their Cross-Border Counterparts

states and provinces--Canada and United State

Dynamical evolution of escaped plutinos, another source of Centaurs

It was shown in previous works the existence of weakly chaotic orbits in the plutino population that diffuse very slowly. These orbits correspond to long-term plutino escapers and then represent the plutinos that are escaping from the resonance at present. In this paper we perform numerical simulations in order to explore the dynamical evolution of plutinos recently escaped from the resonance. The numerical simulations were divided in two parts. In the first one we evolved 20,000 test particles in the resonance in order to detect and select the long-term escapers. In the second one, we numerically integrate the selected escaped plutinos in order to study their dynamical post escaped behavior. Our main results include the characterization of the routes of escape of plutinos and their evolution in the Centaur zone. We obtained a present rate of escape of plutinos between 1 and 10 every 10 years. The escaped plutinos have a mean lifetime in the Centaur zone of 108 Myr and their contribution to the Centaur population would be a fraction of less than 6 % of the total Centaur population. In this way, escaped plutinos would be a secondary source of Centaurs.Comment: Accepted for publication in A&

How Do Canadian Provinces and U.S. States View the Importance of Their Relationship with Their Cross-Border Counterparts

states and provinces--Canada and United State

Introduction Session 11: Canada and U.S. Approaches - Outsourcing, Offshoring, Nearshoring, Legal Aspects, Possible Conflicts, Economic Impact and Job Effects

offshoring, nearshoring, employment--Canada, employment--United State

Introduction Session 11: Canada and U.S. Approaches - Outsourcing, Offshoring, Nearshoring, Legal Aspects, Possible Conflicts, Economic Impact and Job Effects

offshoring, nearshoring, employment--Canada, employment--United State

Origin of craters on Phoebe: comparison with Cassini's data

Phoebe is one of the irregular satellites of Saturn; the images taken by Cassini-Huygens spacecraft allowed us to analyze its surface and the craters on it. We study the craters on Phoebe produced by Centaur objects from the Scattered Disk (SD) and plutinos escaped from the 3:2 mean motion resonance with Neptune and compare our results with the observations by Cassini. We use previous simulations on trans-Neptunian Objects and a method that allows us to obtain the number of craters and the cratering rate on Phoebe. We obtain the number of craters and the greatest crater on Phoebe produced by Centaurs in the present configuration of the Solar System. Moreover, we obtain a present normalized rate of encounters of Centaurs with Saturn of $\dot F = 7.1 \times 10^{-11}$ per year, from which we can infer the current cratering rate on Phoebe for each crater diameter. Our study and the comparison with the observations suggest that the main crater features on Phoebe are unlikely to have been produced in the present configuration of the Solar System and that they must have been acquired when the SD were depleted in the early Solar System. If this is what happened and the craters were produced when Phoebe was a satellite of Saturn, then it had to be captured, very early in the evolution of the Solar System.Comment: Accepted for publication in Astronomy & Astrophysic