Calmness of the Optimal Value in Linear Programming

This research has been partially supported by grant MTM2014-59179-C2-2-P from MINECO, Spain, and FEDER "Una manera de hacer Europa," European Union

Projection-based local and global Lipschitz moduli of the optimal value in linear programming

In this paper, we use a geometrical approach to sharpen a lower bound given in [5] for the Lipschitz modulus of the optimal value of (finite) linear programs under tilt perturbations of the objective function. The key geometrical idea comes from orthogonally projecting general balls on linear subspaces. Our new lower bound provides a computable expression for the exact modulus (as far as it only depends on the nominal data) in two important cases: when the feasible set has extreme points and when we deal with the Euclidean norm. In these two cases, we are able to compute or estimate the global Lipschitz modulus of the optimal value function in different perturbations frameworks.This research has been partially supported by Grants PGC2018-097960-B-C21 and PID2020-116694GB-I00 from MICINN, Spain, and ERDF, ‘A way to make Europe,’ European Union

Subdifferentials and Stability Analysis of Feasible Set and Pareto Front Mappings in Linear Multiobjective Optimization

The paper concerns multiobjective linear optimization problems in R^n that are parameterized with respect to the right-hand side perturbations of inequality constraints. Our focus is on measuring the variation of the feasible set and the Pareto front mappings around a nominal element while paying attention to some specific directions. This idea is formalized by means of the so-called epigraphical multifunction, which is defined by adding a fixed cone to the images of the original mapping. Through the epigraphical feasible and Pareto front mappings we describe the corresponding vector subdifferentials, and employ them to verifying Lipschitzian stability of the perturbed mappings with computing the associated Lipschitz moduli. The particular case of ordinary linear programs is analyzed, where we show that the subdifferentials of both multifunctions are proportional subsets. We also provide a method for computing the optimal value of linear programs without knowing any optimal solution. Some illustrative examples are also given in the paper.Comment: 23 page

Understanding the interplay of carbon and nitrogen supply for ectoines production and metabolic overflow in high density cultures of Chromohalobacter salexigens

Background The halophilic bacterium Chromohalobacter salexigens has been proposed as promising cell factory for the production of the compatible solutes ectoine and hydroxyectoine. This bacterium has evolved metabolic adaptations to efficiently grow under high salt concentrations by accumulating ectoines as compatible solutes. However, metabolic overflow, which is a major drawback for the efficient conversion of biological feedstocks, occurs as a result of metabolic unbalances during growth and ectoines production. Optimal production of ectoines is conditioned by the interplay of carbon and nitrogen metabolisms. In this work, we set out to determine how nitrogen supply affects the production of ectoines. Results Chromohalobacter salexigens was challenged to grow in media with unbalanced carbon/nitrogen ratio. In C. salexigens, overflow metabolism and ectoines production are a function of medium composition. At low ammonium conditions, the growth rate decreased importantly, up to 80%. Shifts in overflow metabolism were observed when changing the C/N ratio in the culture medium. 13C-NMR analysis of ectoines labelling revealed a high metabolic rigidity, with almost constant flux ratios in all conditions assayed. Unbalanced C/N ratio led to pyruvate accumulation, especially upon N-limitation. Analysis of an ect − mutant demonstrated the link between metabolic overflow and ectoine biosynthesis. Under non ectoine synthesizing conditions, glucose uptake and metabolic overflow decreased importantly. Finally, in fed-batch cultures, biomass yield was affected by the feeding scheme chosen. High growth (up to 42.4 g L−1) and volumetric ectoine yields (up to 4.21 g L−1) were obtained by minimizing metabolite overflow and nutrient accumulation in high density cultures in a low nitrogen fed-batch culture. Moreover, the yield coefficient calculated for the transformation of glucose into biomass was 30% higher in fed-batch than in the batch culture, demonstrating that the metabolic efficiency of C. salexigens can be improved by careful design of culture feeding schemes. Conclusions Metabolic shifts observed at low ammonium concentrations were explained by a shift in the energy required for nitrogen assimilation. Carbon-limited fed-batch cultures with reduced ammonium supply were the best conditions for cultivation of C. salexigens, supporting high density growth and maintaining high ectoines production.España, Ministerio de Ciencia e Innovación BIO2011-29233-C02-01España, Ministerio de Economía y Competitividad BIO2014-54411-C2-1-

Cerdos, acumulación y producción de naturaleza barata

El objetivo de este artículo es explorar la ecología-mundo de la producción capitalista de carne de cerdo, a partir de los planteamientos teóricos de Jason W. Moore, según los cuales la naturaleza producida por el capital implica superar la distinción cartesiana entre explotación del trabajo y la naturaleza. Este artículo se centra en el momento histórico de la constitución de un régimen neoliberal y global de la industria cárnica de cerdo. Entre 1950-1970, el régimen alimentario intensivo reestructuró la producción ganadera de cerdos en España y otras muchas geografías de la economía-mundo; el cual a su vez sentó las bases para la transición al régimen corporativo o global (1980 hasta la actualidad), según una nueva ecología-mundo de producción de “cerdos capitalistas”. En la primera parte se aborda la ecología-mundo de la industria del cerdo a partir de la periodificación de regímenes alimentarios propuesta por el sociólogo Philip McMichael (2016): imperial, intensivo y corporativo. Tras la Segunda Guerra Mundial, se produjo desde EEUU la internacionalización del régimen alimentario intensivo (1950-1970) que reestructuró la producción ganadera de cerdos en España y otras muchas geografías de la economía-mundo; el cual a su vez sentó las bases para la transición al régimen corporativo o global (1980 hasta la actualidad). En la segunda parte, siguiendo el enfoque de Jason W. Moore sobre las cuatro mercancías baratas requeridas por la valorización capitalista, mostramos cómo se ha constituido históricamente la carne de cerdo como un alimento barato, en el contexto de la expansión de una demanda interna derivada de la integración de las clases trabajadoras en la nueva norma de consumo de masas. Tomamos como referencia empírica España, y concretamente la Región de Murcia, como nuevo polo productivo de carne de cerdo. Se analizan las fronteras de trabajo barato y de naturaleza barata para detectar las fuentes de trabajo no remunerado que han posibilitado la valorización capitalista. El trabajo de investigación que fundamenta este artículo se basa en entrevistas cualitativas a actores sociales implicados, directa o indirectamente, en esta problemática (políticos, ganaderos, sindicalistas, trabajadores, ecologistas, líderes vecinales, etc.), así como en observaciones sobre el terreno y uso de fuentes secundarias (estadísticas oficiales, páginas web corporativas, documentos oficiales, etc.)

Metal mobility and bioaccessibility from cyanide leaching heaps in a historical mine site

Unlike acidic sulfide mine wastes, where metal/loid mobility and bioaccessibility has been widely studied, less attention has been paid to alkaline cyanide heap leaching wastes. Thus, the main goal of this study is to evaluate the mobility and bioaccessibility of metal/loids in Fe-rich (up to 55%) mine wastes resulting from historical cyanide leaching activities. Wastes are mainly composed of oxides/oxyhydroxides (i.e. goethite and hematite), oxyhydroxisulfates (i.e. jarosite), sulfates (i.e., gypsum, evaporitic sulfate salts), carbonates (i.e., calcite, siderite) and quartz, with noticeable concentrations of metal/loids (e.g., 1453–6943 mg/kg of As, 5216–15,672 mg/kg; of Pb, 308–1094 mg/kg of Sb, 181–1174 mg/kg of Cu, or 97–1517 mg/kg of Zn). The wastes displayed a high reactivity upon rainfall contact associated to the dissolution of secondary minerals such as carbonates, gypsum, and other sulfates, exceeding the threshold values for hazardous wastes in some heap levels for Se, Cu, Zn, As, and sulfate leading to potential significant risks for aquatic life. High concentrations of Fe, Pb, and Al were released during the simulation of digestive ingestion of waste particles, with average values of 4825 mg/kg of Fe, 1672 mg/kg of Pb, and 807 mg/kg of Al. Mineralogy may control the mobility and bioaccessibility of metal/loids under rainfall events. However, in the case of the bioaccessible fractions different associations may be observed: i) the dissolution of gypsum, jarosite and hematite would mainly release Fe, As, Pb, Cu, Se, Sb and Tl; ii) the dissolution of an un-identified mineral (e.g., aluminosilicate or Mn oxide) would lead to the release of Ni, Co, Al and Mn and iii) the acid attack of silicate materials and goethite would enhance the bioaccessibility of V and Cr. This study highlights the hazardousness of wastes from cyanide heap leaching, and the need to adopt restoration measures in historical mine sites.This work was supported by the Spanish Ministry of Economic and Competitiveness through the projects TRAMPA (PID2020–119196RBC21) and by H2020 European Institute of Innovation and Technology (EIT RawMaterials) through the project Modular recovery process services for hydrometallurgy and water treatment (MORECOVERY). This work was partially supported by FCT (Portugal) through contract UID/ Multi/04349/2019. C.R C´anovas thanks the Spanish Ministry of Science and Innovation for the Postdoctoral Fellowship granted under application reference RYC2019–027949-I. M.D. Basallote thanks the Spanish Ministry of Science and Innovation for the Postdoctoral Fellowship granted under application reference IJC 2018–035056-I. The authors would also like to thank to Prof. Edward D. Burton, Ph.D (Editor) and three anonymous reviewers for the support and comments that notably improved the quality of the original paper

Exploring the perception of barriers to a dual career by student-athletes with/out disabilities

n recent years, there has been an increase in knowledge about the barriers experienced by people with disabilities in the education system or sports. However, no studies have analyzed the barriers for those who try to succeed in both disciplines (dual career). The purpose of this study was to examine the barriers faced by student-athletes with/out disability to a dual career combining studies and sport. Two groups were involved in the study (n = 162): student-athletes with disabilities (n = 79) and student-athletes without disabilities (n = 83). Data collected included: (a) socio-demographic aspects; and (b) barriers towards achieving a good balance between sport and academics during the dual career, through the "Perceptions of dual career student-athletes" (ESTPORT) questionnaire. The results showed that student-athletes with disabilities were more likely to perceive in a greater extent the barriers, the university is far from my home (p = 0.007) and the university is far from my training site (p = 0.006), I find myself unable to balance study and training time (p = 0.030), I have to take care of my family (p<0.001), and my current job does not allow me to study enough (p<0.001). The MANOVA analysis showed that the factors gender, competitive level, and employment status had an influence on the perception of some barriers between groups. In conclusion, student-athletes with disabilities perceived barriers more strongly than those without disabilities, and measures are needed to ensure their inclusion in the education system

Nanoencapsulated Clove Oil Applied as an Anesthetic at Slaughtering Decreases Stress, Extends the Freshness, and Lengthens Shelf Life of Cultured Fish

In the aquaculture industry, fish are stunned using a wide range of methods, but all of them trigger stress responses and affect the fish flesh quality. Chilled water is considered one of the most efficient methods, but even this is not a stress‐free experience for the fish. Anesthetics included in the ice slurry or in water could decrease this stress and delay the loss of flesh quality. In this work, we analyze the effect of clove oil (CO) nanoencapsulated in β‐cyclodextrins (β‐CD) (CO + β‐CD), incorporated in the stunning bath, on the stress response and the organoleptic attributes of fresh marine and freshwater fish from four economically important fish species: Atlantic salmon, European seabass, Nile tilapia, and Rainbow trout. CO + β‐CD reduces the time required to induce anesthesia, independently of water salinity, habitat or water temperature. The plasmatic glucose and cortisol levels decreased in all four species, although the concentrations of CO varied between species. Moreover, plasmatic lactate level differed between the marine and freshwater fish. The use of CO + β‐CD extended the shelf life of fish from all the species studied (by 3–7 days). In conclusion, using CO encapsulated in β‐CD for anesthetizing fish can be regarded as an improved fish‐stunning technique that reduces the anesthesia‐induction time, decreases the stress response, and extends the shelf life of fresh fish.Versión del edito