University of Cagliari

About: University of Cagliari is a education organization based out in Cagliari, Italy. It is known for research contribution in the topics: Population & Dopamine. The organization has 11029 authors who have published 29046 publications receiving 771023 citations. The organization is also known as: Università degli Studi di Cagliari & Universita degli Studi di Cagliari.

Optimisation of embedded generation sizing and siting by using a double trade-off method

Abstract: Distribution System Operators have the duty of managing the distribution system safely and efficiently. Distribution revenues are generally based on asset value but revenue systems based to some extent on network performance (e.g. on the level of losses or reliability) are becoming common in many countries. Thus the distribution planner has to maximise the profit of the investments for the system development and to improve the performance of the system as well. In many case the goals are conflicting and multiobjective planning criteria may be adopted to reduce network costs and investments and to maximise some specific performance (e.g. network reliability). Furthermore, with multiobjective programming the distribution planner has the possibility of choosing a trade-off solution in a set of acceptable solutions by applying criteria to minimise risks in uncertain scenarios. These features are particularly useful whether, according to the EU directive EU/2003/54, Embedded Generation (EG) and DSM are considered as possible planning alternatives to be compared with more traditional development actions in the search for the best solution to planning problems. In this context, a methodology is presented based on multiobjective programming and decision theory which helps the decision maker to find the best development plan for the system by using the EG as a development option and by explicitly managing risks and uncertainties. In particular, the proposed methodology solves the problem of maximising the network performance by optimising some power quality indicators, like voltage quality and harmonic distortion, and by minimising the network costs (e.g. energy losses or upgrade investments) with an optimised use of EG. For this reason, the problem of the optimal sizing and siting of EG has been reformulated as a constrained, multiobjective, and nondifferentiable optimisation problem. The main idea is to apply a double trade-off procedure: the first trade-off, by means of a multiobjective /spl epsiv/-constrained technique, allows a wide family of good EG siting and sizing solutions for all the scenarios considered (e.g. associated to a different set of wind speed at all the possible locations); the second one allows isolating the most robust solutions. In this way the planner is completely free to drive the optimisation in a certain direction without loosing objectivity and generality. Simulation results obtained by using the proposed procedure on a test system demonstrate that alternatives disregarded by the decision theory application can result the most interesting ones.

The effect of protest votes on the estimates of WTP for use values of recreational sites

Abstract: Contingent valuation studies are often characterized by a considerable number of protest responses, which may cause selectivity bias on the final estimates for WTP. Sample selection models can detect and – if necessary – correct selectivity bias. In economic applications where the relevant dependent variable is continuous, sample selection models are generally estimated using Heckman's 2-step method rather than the FIML estimator. Either method has its own drawback: computational complexity for the FIML method, susceptibility to collinearity problems for the 2-step method. Using data on valuation of forest resources for recreational use, we analyse the performance of the two estimators. In this application, given the presence of some collinearity, the FIML is preferred to the 2-step method. A procedure is outlined to deal with selectivity problems in similar settings.

Endogenous Fatty Acid Ethanolamides Suppress Nicotine-Induced Activation of Mesolimbic Dopamine Neurons through Nuclear Receptors

Abstract: Nicotine stimulates the activity of mesolimbic dopamine neurons, which is believed to mediate the rewarding and addictive properties of tobacco use. Accumulating evidence suggests that the endocannabinoid system might play a major role in neuronal mechanisms underlying the rewarding properties of drugs of abuse, including nicotine. Here, we investigated the modulation of nicotine effects by the endocannabinoid system on dopamine neurons in the ventral tegmental area with electrophysiological techniques in vivo and in vitro. We discovered that pharmacological inhibition of fatty acid amide hydrolase (FAAH), the enzyme that catabolizes fatty acid ethanolamides, among which the endocannabinoid anandamide (AEA) is the best known, suppressed nicotine-induced excitation of dopamine cells. Importantly, this effect was mimicked by the administration of the FAAH substrates oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), but not methanandamide, the hydrolysis resistant analog of AEA. OEA and PEA are naturally occurring lipid signaling molecules structurally related to AEA, but devoid of affinity for cannabinoid receptors. They blocked the effects of nicotine by activation of the peroxisome proliferator-activated receptor-α (PPAR-α), a nuclear receptor transcription factor involved in several aspects of lipid metabolism and energy balance. Activation of PPAR-α triggered a nongenomic stimulation of tyrosine kinases, which might lead to phosphorylation and negative regulation of neuronal nicotinic acetylcholine receptors. These data indicate for the first time that the anorexic lipids OEA and PEA possess neuromodulatory properties as endogenous ligands of PPAR-α in the brain and provide a potential new target for the treatment of nicotine addiction.