Multi-objective optimization of environmentally conscious chemical supply chains under demand uncertainty

In this work, we analyze the effect of demand uncertainty on the multi-objective optimization of chemical supply chains (SC) considering simultaneously their economic and environmental performance. To this end, we present a stochastic multi-scenario mixed-integer linear program (MILP) with the unique feature of incorporating explicitly the demand uncertainty using scenarios with given probability of occurrence. The environmental performance is quantified following life cycle assessment (LCA) principles, which are represented in the model formulation through standard algebraic equations. The capabilities of our approach are illustrated through a case study. We show that the stochastic solution improves the economic performance of the SC in comparison with the deterministic one at any level of the environmental impact.The authors wish to acknowledge support from the Spanish Ministry of Education and Science (ENE2011-28269-C03-03, ENE2011-22722, DPI2012-37154-C02-02, CTQ2009-14420-C02, CTQ2012-37039-C02) and Programa DRAC de la Xarxa Vives d’Universitats

Pobreza en España: jóvenes y mujeres en los espacios sociales de la vulnerabilidad

This number of Quaderns presents the results of two research projects of the program I+D+i financed by the Spanish Ministry of Education for the period 2008 to 2011. The first project is called 'New poverty and social exclusion among youth in Spain' and was supervised by Ph. D. Ignasi Brunet. The second project was developed under the name of 'Poverty, social exclusion and gender inequality in Spain' and was supervised by Ph. D. Ángel Belzunegui. Both projects counted with a group formed by researchers from six Spanish universities from different regions where field work was carried out: Andalucía, Aragón, Cataluña, Comunidad Valenciana, Murcia y País Vasco. The first project has analyzed poverty and youth exclusion in Spain, focusing on the logic that lays behind the social processes of impoverishment and exclusion that effect young people. The second project intended to analyze from a gender perspective the logic of impoverishment processes that affect women, as well as to analyze how women interpret and define poverty

Steady-state global optimization of metabolic non-linear dynamic models through recasting into power-law canonical models

<p>Abstract</p> <p>Background</p> <p>Design of newly engineered microbial strains for biotechnological purposes would greatly benefit from the development of realistic mathematical models for the processes to be optimized. Such models can then be analyzed and, with the development and application of appropriate optimization techniques, one could identify the modifications that need to be made to the organism in order to achieve the desired biotechnological goal. As appropriate models to perform such an analysis are necessarily non-linear and typically non-convex, finding their global optimum is a challenging task. Canonical modeling techniques, such as Generalized Mass Action (GMA) models based on the power-law formalism, offer a possible solution to this problem because they have a mathematical structure that enables the development of specific algorithms for global optimization.</p> <p>Results</p> <p>Based on the GMA canonical representation, we have developed in previous works a highly efficient optimization algorithm and a set of related strategies for understanding the evolution of adaptive responses in cellular metabolism. Here, we explore the possibility of recasting kinetic non-linear models into an equivalent GMA model, so that global optimization on the recast GMA model can be performed. With this technique, optimization is greatly facilitated and the results are transposable to the original non-linear problem. This procedure is straightforward for a particular class of non-linear models known as Saturable and Cooperative (SC) models that extend the power-law formalism to deal with saturation and cooperativity.</p> <p>Conclusions</p> <p>Our results show that recasting non-linear kinetic models into GMA models is indeed an appropriate strategy that helps overcoming some of the numerical difficulties that arise during the global optimization task.</p

A ventral rotational skin flap to improve cosmesis and avoid chordee recurrence in epispadias repair.

OBJECTIVE: To describe a technical modification that facilitates dorsal skin closure, improves cosmesis and eliminates chordee recurrence secondary to contracture of the dorsal penile skin in the repair of epispadias. PATIENTS AND METHODS: Eleven patients with penopubic epispadias (mean age 1.8 years) had the epispadias repaired using a modified ventral penile skin flap. Four patients had isolated epispadias and seven had had a previous primary closure of bladder exstrophy. Nine patients underwent the Cantwell-Ransley technique, leaving the meatus in a glanular position. Two patients were repaired using the penile disassembly technique of Mitchell and Bägli, because they had a short urethral plate. A ventral island skin flap was fashioned, starting at the base of the penis. Dissection was carried ventrally into the scrotum to allow for adequate dorsal flap transposition. The flap was rotated laterally to shift the suture line from the midline and to cover the dorsal aspect of the penis with untouched penile shaft skin. Redundant ventral foreskin was discarded. RESULTS: All patients had an uneventful course after surgery. Dorsal penile skin was viable in every case and no patient developed recurrence of chordee or a urethrocutaneous fistula. The cosmetic result was excellent in all patients. CONCLUSIONS: Dorsal skin closure using lateral rotation of ventral penile skin flap improves cosmesis after epispadias repair and eliminates the recurrence of chordee secondary to midline dorsal scarring