Software tools for stochastic programming: A Stochastic Programming Integrated Environment (SPInE)

SP models combine the paradigm of dynamic linear programming with modelling of random parameters, providing optimal decisions which hedge against future uncertainties. Advances in hardware as well as software techniques and solution methods have made SP a viable optimisation tool. We identify a growing need for modelling systems which support the creation and investigation of SP problems. Our SPInE system integrates a number of components which include a flexible modelling tool (based on stochastic extensions of the algebraic modelling languages AMPL and MPL), stochastic solvers, as well as special purpose scenario generators and database tools. We introduce an asset/liability management model and illustrate how SPInE can be used to create and process this model as a multistage SP application

Growth and Pollution Convergence: Theory and Evidence

Stabilizing pollution levels in the long run is a pre-requisite for sustainable growth. We develop a neoclassical growth model with endogenous emission reduction predicting that, along optimal sustainable paths, pollution growth rates are (i) positively related to output growth (scale effect) and (ii) negatively related to emission levels (defensive effect). This dynamic law reduces to a convergence equation that is empirically tested for two major and regulated air pollutants - sulfur oxides and nitrogen oxides - with a panel of 25 European countries spanning the years 1980-2005. Traditional parametric models are rejected by the data. More flexible regression techniques confirm the existence of both the scale and the defensive effect, supporting the model predictions.Air pollution, convergence, economic growth, nonparametric regressions

Corrosion behavior of dental implants immersed into human saliva: Preliminary results of an in vitro study

Over the years, dif- ferent implant surfaces have been used to try to maximize bone to implant contact. The aim of this study was to compare levels of metallic ions and particles dissolution collected from two dif- ferent dental implants surfaces immersed into human saliva. PATIENTS AND METHODS: A total of 60 den- tal implants were tested. Group A: sanded with aluminium oxide medium grade particles and ac- id-etched; Group B: micro-sanded with calcium phosphate powders and acid-etched. Forty im- plants were immersed in 20 ml of human saliva, twenty, as a control, in sterile saline solution. ICP-MS was performed to detect any metallic ions released from dental implants at T0, on day 1 (T1), on day 3 (T2), after one week (T3), on day 14 (T4), after 3 months (T5) and after 6 months (T6). RESULTS: Dissolution of metallic particles of titanium and nickel, absent in human saliva (T0), were found after one week (T3) for Group B and after 3 months (T5) for Group A. Vanadium was already detected in small concentrations in either group after 1 day, with an exponential growth for Group B. CONCLUSIONS: Preliminary results reported signi cant values of Ti, Ni and V released by Group B, showing for the rst time statistically signi cant values of vanadium

Typology and evolution of the new mineralogy developed at the mine waste dump of Valdarcas (Vila Nova de Cerveira - N Portugal) - Environmental Implications

[Abstract] The abandoned waste dump of Valdarcas tungsten skarn deposit — Vila Nova de Cerveira, N Portugal, represents a key site, appropriate to study the environmental problems related to deactivated sulfide tails. The tungsten mineralization which occurs in coexistence with metallic sulfide minerals, calcium silicates and carbonates, confers to this deposit special characteristics. The water-mineral interactions at the waste dump surface, leads to the generation of acid mine waters (AMD) with high content of metals and sulfate (ASW), related to the sulfide minerals alteration. Consequently occurs the contamination of the Coura river system Simultaneously the alteration of calcium silicates and carbonates produces neutralization reactions, and the development of a new mineralogy - soluble salts, iron crusts and clay minerals. The new paragenesis reflects the occurrence of wet-dry cycles, related to the seasonal variations of rainfall. These geochemical trends and their role in the process evolution of the waste dump surface to the stabilization are the main subject of this work.The soluble salts, iron crusts and the clay minerals have different capacities and mechanisms to fixate the chemical potential associated to the AMD/ASW. The instability of the salt minerals leads only to a temporary fixation of the contaminant elements. On the other hand, the crusts are capable of fixate efficiently these elements, specially the iron oxides, furthermore, they isolate the reactive minerals from the weathering agents. Consequently they limit the aquatic contamination, the dispersion area of the environmental impact and contribute to the chemical stabilization of the waste dum