Aplicaciones de modelos predictivos en evaluación de riesgo de "Listeria monocytogenes" en productos mínimamente procesados

En la presente Tesis Doctoral se estudia el comportamiento de un microorganismo patógeno de interés alimentario. Listeria monocytogenes, a través del desarrollo de diferentes tipos de modelos predictivos y su posterior aplicación en un esquema de Evaluación Cuantitativa del Riesgo Microbiano (ECRM). En primer lugar, se procede a la estimación de los principales parámetros de crecimiento microbiano (fase de latencia, tasa máxima de crecimiento y densidad máxima de población), así como la probabilidad de crecimiento bajo diferentes condiciones ambientales sobre medios de cultivo. Posteriormente se monitoriza la calidad microbiológica y sensorial de espárragos blancos pasteurizados a diferentes temperaturas de almacenamiento, junto con la incidencia y evolución de crecimiento de L.monocytogenes. A través de la información obtenida, y junto con una recopilación de datos procedentes de la literatura científica, se aborda la aplicación de los modelos predictivos desarrollados en un esquema de ECRM mediante la estimación del número final de células presentes en el momento de consumo y el número de casos/año sobre una población. La metodología seguida en la presente Tesis doctoral constituye una vía relativamente sencilla de evaluar la seguridad microbiológica de un proceso alimentario mediante la integración modelos matemáticos dentro de un esquema de EC

Los criterios microbiológicos: principios para su establecimiento y aplicación en la seguridad alimentaria

Legislation on food safety has led to the standardi­sation of food production which, together with existing quality certifications, aim to increase the level for protection of pu­blic health. The need is recognized for the agri-food industry to have tools to harmonize their production and to adequately manage their quality systems in order to increase consumers’ confidence. The implementation of microbiological criteria is focused on facilitating this harmonization by enabling differen­tiation of defective lots and acting as control tools at the indus­trial level. Therefore, knowledge on the principles, components and factors influencing the efficiency of microbiological criteria may be helpful to better understand the consequences of their application. In the present paper the main principles, methodo­logies and applications of microbiological criteria in foods are addressed for their implementation as part of management quality systems in agri-food industries. In addition, potential li­mitations and impacts of microbiological criteria on food safety are discussed.La legislación en materia de seguridad alimentaria ha ido encaminada hacia una mayor estandarización de las produccio­nes que, junto con las certificaciones de calidad existentes, tienen como objetivo un incremento del nivel de protección de la salud pública. Está constatada la necesidad de que la industria agroali­mentaria disponga de herramientas con las que poder armonizar sus producciones y gestionar adecuadamente sus sistemas de cali­dad para ofrezcer una mayor confianza a los consumidores finales. La implementación de los criterios microbiológicos está enfocada a facilitar dicha armonización posibilitando la discriminación de lo­tes defectuosos y actuando como herramientas de control en las industrias. Por tanto, el conocimiento de los principios, componen­tes y factores que influyen sobre la eficiencia de los criterios micro­biológicos ayuda a un mejor entendimiento de las consecuencias de su aplicación. En el presente artículo se abordan los principales fundamentos, metodologías y aplicaciones de los criterios micro­biológicos en alimentos de cara a su implementación en los sis­temas de calidad de las industrias agroalimentarias. Asimismo, se discuten algunos aspectos sobre las posibles limitaciones y reper­cusiones sobre la seguridad alimentaria

Hypercube algorithms on mesh connected multicomputers

A new methodology named CALMANT (CC-cube Algorithms on Meshes and Tori) for mapping a type of algorithm that we call CC-cube algorithm onto multicomputers with hypercube, mesh, or torus interconnection topology is proposed. This methodology is suitable when the initial problem can be expressed as a set of processes that communicate through a hypercube topology (a CC-cube algorithm). There are many important algorithms that fit into the CC-cube type. CALMANT is based on three different techniques: (a) the standard embedding to assign the processes of the algorithm to the nodes of the mesh multicomputer; (b) the communication pipelining technique to increase the level of communication parallelism inherent in the CC-cube algorithms; and (c) optimal message-scheduling algorithms proposed in this work in order to avoid conflicts and minimizing in this way the communication time. Although CALMANT is proposed for multicomputers with different interconnection network topologies, the paper only focuses on the particular case of meshes.Peer ReviewedPostprint (published version

A study of the communication cost of the FFT on torus multicomputers

The computation of a one-dimensional FFT on a c-dimensional torus multicomputer is analyzed. Different approaches are proposed which differ in the way they use the interconnection network. The first approach is based on the multidimensional index mapping technique for the FFT computation. The second approach starts from a hypercube algorithm and then embeds the hypercube onto the torus. The third approach reduces the communication cost of the hypercube algorithm by pipelining the communication operations. A novel methodology to pipeline the communication operations on a torus is proposed. Analytical models are presented to compare the different approaches. This comparison study shows that the best approach depends on the number of dimensions of the torus and the communication start-up and transfer times. The analytical models allow us to select the most efficient approach for the available machine.Peer ReviewedPostprint (published version

Changes on the bioavailability of DDT in soil by addition of lignite and coal solubilizing bacteria

ABSTRACT: DDT is an organochlorine insecticide that is persistent and exhibits residuality in the environment. This study assessed the effect of the application of lignite [low rank coal (LRC)] and coal solubilizing bacteria (CSB), on the bioavailability of DDT in soil with low organic matter content. In doing this, three trials were designed; in the first trial, soil samples were treated with CSB and LRC for 30 days and, afterwards, they were immersed in a DDT solution at water solubility limit and, lastly, the remaining DDT in the aqueous solution was determined. In the second trial, soil samples previously contaminated with DDT were treated with LRC and CSB. After 30 days of this interaction, the soil samples were immersed in water and the remaining DDT in solution was subsequently determined. The third trial was similar to the latter, but the interaction lasted for six months. In the first experiment, treatments with LRC and LRC + CSB, showed 8.16 and 3.4 % of remaining DDT respectively, thus indicating the retention of the compound in the soil. In the second trial, the treatment with CSB greatly reduced the bioavailable DDT (0.007 ppm), compared to the control (0.014 ppm); this is possible since these bacteria use DDT as a carbon source. In the third trial, the highest reduction in the bioavailability of DDT took place in LRC and LRC + CSB treatments; this trial also detected DDD produced from DDT transformation, which showed the same behavior; the interaction timeframe favors adsorption and copolymerization of pollutants to humified organic matter (HOM) in soil. Use of LRC as a source of HOM represents a promising strategy for the treatment of soils with low organic matter content affected by persistent organic pollutants such as DDT.RESUMEN: El DDT es un insecticida organoclorado, es persistente y presenta residualidad en el ambiente. En este trabajo se evaluó el efecto de la aplicación de lignito [carbón de bajo rango (CBR)] y bacterias solubilizadoras de carbón (BSC), sobre la biodisponibilidad de DDT en un suelo con bajo contenido de materia orgánica. Para conseguirlo se hicieron tres experimentos; en el primer ensayo las muestras de suelo fueron tratadas con BSC y CBR por 30 días, después fueron sumergidas en una solución de DDT al límite de solubilidad en agua, posteriormente se determinó el DDT remanente en la solución acuosa. En un segundo ensayo, las muestras de suelo, contaminadas previamente con DDT, fueron tratadas con CBR y BSC. Después de 30 días de interacción las muestras de suelo fueron sumergidas en agua y fue determinado el DDT remanente en la solución. El tercer ensayo fue similar al anterior, pero el tiempo de interacción fue de seis meses. En el primer experimento, los tratamientos con CBR y CBR + BSC, presentaron un porcentaje de DDT remanente de 8.16 y 3.4 % respectivamente, esto indica la retención del compuesto en el suelo. En el segundo ensayo, el tratamiento con BSC redujo significativamente el DDT biodisponible (0.007 ppm), comparado con el control (0.014 ppm); es posible que estas bacterias utilicen DDT como fuente de carbono. En el tercer experimento, los tratamientos con CBR y CBR + BSC presentaron la mayor reducción en la biodisponibilidad de DDT, en este ensayo también se detectó el DDD generado a partir de la transformación del DDT, el cual mostró el mismo comportamiento; el tiempo de interacción favorece la adsorción y copolimerización de los contaminantes a la materia orgánica humificada (MOH) del suelo. El uso de CBR como fuente de MOH representa una estrategia promisoria para el tratamiento de suelos con bajo contenido de materia orgánica afectados por contaminantes orgánicos persistentes, tales como DDT

First evidence of lamprophyric magmatism within the Subbetic Zone (Southern Spain)

Two drillings carried out at Cerro Prieto (Province of Málaga), together with additional geophysical data, revealed the existence of an igneous body formed of rock-types previously unknown in the Subbetic zone. The recovered rocks, emplaced under hypoabyssal conditions, are predominantly porphyric, containing olivine, diopside and TiO2-rich phlogopite phenocrysts (up to 1-2 mm in size) within a micro-to-hypocrystalline groundmass componed of alkali-feldspar, diopside, phlogopite and abundant magnetite, and could be classified as "alkali minettes" lamprophyres. They contain numerous xenocrysts corroded by the magma and centimetric ultrafemic xenoliths deriving from the mantle. Clinopyroxenes yield crystallisation temperatures from about 1150 to 1320º C and pressures ranging from about 4 to 17 kbar, suggesting 50 km as the minimum depth of the magma sources. The chemical compositions of these lamprophyres are similar to intra plate alkali-basalts, derived from oceanic-island-basaltic-type highly metasomatized mantle sources. 40Ar/39Ar dating of a phlogopite mineral separate gave an age of 217±2.5 Ma. However, these rocks are more similar to the Permian alkaline lamprophyres in the Spanish Central System than to the Mesozoic dolerites and basalts widespread throughout the Subbetic Zone. We propose that the Cerro Prieto subvolcanic event represents the onset of a widespread magmatic phase induced by the post-Hercynian extensional tectonic activity that also affected the whole South-Iberian Paleomargin, within a geodynamic context that ultimately led to the opening of the Atlantic and the Neotethys oceans, accompanied by intrusion of basic magmas along their continental margins

Evaluation of water-assisted UV-C light and its additive effect with peracetic acid for the inactivation of Listeria monocytogenes, Salmonella enterica and murine norovirus on whole and fresh-cut strawberries during shelf-life

BACKGROUND: The purpose of the present study was to examine the inactivation of Salmonella enterica (50 ∼L; 109 CFU g−1), Listeria monocytogenes (50 ∼L; 109 CFU g−1), and murine norovirus (MNV-1; 50 ∼L; 107 50% tissue culture infectious dose (TCID50) mL−1) on whole and fresh-cut strawberries after 2 min disinfection treatments (water (H2O), chlorine 200 mg L−1 (NaClO), water-assisted ultraviolet-C (UV-C) (WUV), and the combination WUV and 40 mg L−1 of PA (WUV + PA)) in a water tank (15 L) equipped with 4 UV-C lamps (17.2 W each), and after 7 days of cold storage (4 and 10 °C). For MNV-1, dry UV-C treatment (DUV) was also tested. For all UV-C treatments, an irradiation dose of 1.3 kJ m−2 was used. RESULTS: When strawberries were washed with WUV, L. monocytogenes and S. enterica were reduced by 2.8 and 2.2 log CFU g−1, respectively. The addition of 40 mg L−1 of PA to WUV (WUV + PA) increased the reduction range of L. monocytogenes and S. enterica by 1.9 and 0.8 log, respectively. Regarding the wash water, no pathogens were recovered after the WUV + PA treatment (detection limit 50 CFU mL−1). Depending on storage conditions (7 days at 4 or 10 °C), reductions observed were 0.5 to 2.0 log for S. enterica and 0.5 to 3.0 log for L. monocytogenes. The reductions in MNV-1 titer after disinfection treatments ranged from 1.3 to 1.7 log. No significant differences between storage conditions were observed for MNV-1: titers did not decline or were reduced up to 0.3 log after 7 days of cold storage. CONCLUSION: The three-way action for disinfecting strawberries by UV-C irradiation and PA, plus the physical removal of the microorganisms by agitated water, are effective against foodborne pathogens on strawberries and water wash. During storage, WUV had a larger impact on the inactivation kinetics of S. enterica. Storage had little impact on MNV-1 inactivation.info:eu-repo/semantics/publishedVersio

Conformance Verification of Normative Specifications using C-O Diagrams

C-O Diagrams have been introduced as a means to have a visual representation of normative texts and electronic contracts, where it is possible to represent the obligations, permissions and prohibitions of the different signatories, as well as what are the penalties in case of not fulfillment of their obligations and prohibitions. In such diagrams we are also able to represent absolute and relative timing constrains. In this paper we consider a formal semantics for C-O Diagrams based on a network of timed automata and we present several relations to check the consistency of a contract in terms of realizability, to analyze whether an implementation satisfies the requirements defined on its contract, and to compare several implementations using the executed permissions as criteria.Comment: In Proceedings FLACOS 2012, arXiv:1209.169

Analysis of bullying levels and its relationship with physical activity in Primary Education

Este estudio pretende conocer la relación entre la percepción de acoso entre iguales y el nivel de actividad física en estudiantes de Primaria. La muestra estuvo compuesta por 95 alumnos, con edades comprendidas entre los 9 y los 12 años, a los cuales se les administró el Cuestionario de Acoso entre Iguales y la traducción al español del Physician-based Assessment and Counseling for Exercise. Los resultados obtenidos mostraron unos niveles bajos tanto de actividad física como de percepción de acoso entre iguales. Se encontraron valores más altos de inconformismo de género y nivel de actividad física en los chicos, mientras que las chicas mostraron valores superiores en el maltrato verbal por falta de atractivo físico. Las comparaciones de nivel educativo muestran mayores niveles tanto en las conductas de acoso como en el nivel de actividad física en los alumnos de mayor edad. No se han encontrado correlaciones significativas entre el nivel de actividad física y las conductas de acosoThe objective of this study is to understand the relationship between the perception of peer harassment and the level of physical activity in primary school students. The sample consisted of 95 students, aged between 9 and 12 years, who answered the Peer Harassment Questionnaire and the translation to Spanish of the Physician-based Assessment and Counselling for Exercise to measure both variables. The results obtained showed low levels of physical activity and perception of bullying among peers were obtained. Significant differences in gender nonconformity and higher level of physical activity were found in boys, while girls showed significantly higher values in verbal abuse due to lack of physical attractiveness. Comparisons of educational level show higher levels in all areas, both of harassment and physical activity level in older students. No significant correlations have been found between the level of physical activity and bullying behaviour, so it seems that at these ages may not yet have influenc

Food Safety Risk Management

It is a principal aim of governments to assure the safety of societies in all sectors. In the food field, safety has been dealt with for a long time by making decisions in an empirical manner. Recently, risk management has been appointed as the formal scientific-based approach to address food safety issue