380 research outputs found
Caractérisation des systèmes de production ovine dans la zone de "Sierra del Segura y la Sagra", Espagne
[FR] Le présent article se propose d¿analyser les caractéristiques les plus saillantes du secteur ovin
dans une partie de la zone géographique sous Indication Géographique Protégée (IGP) "Cordero de
Segura y la Sagra". Une enquête a été menée sur 93 propriétaires d¿élevages, dans l'objectif de connaître
la situation du secteur dans cette zone. Les questions concernaient les sujets suivants: caractéristiques du
troupeau, âge, niveau d'études, ouvriers à la ferme, continuité des activités de la ferme. La taille moyenne
du troupeau est de 378 animaux et la race "Segureña" est prédominante (99%). Dans 93,4% des cas
l¿éleveur travaille à temps plein dans l¿exploitation et le revenu principal est la vente d¿agneaux pour la
viande, mais seulement 9,7% des éleveurs font partie d¿une coopérative pour la commercialisation. L'âge
moyen du fermier est de 50 ans et 87,1% des éleveurs n¿ont pas d¿études ou de faible niveau. La moyenne
du travail employé est de 1,31 UTA, essentiellement de type familial. Seulement dans 12% des cas il existe
une sécurité de la continuité de l'activité. Les résultats obtenus montrent qu'il est nécessaire de parvenir à
de meilleures conditions socioéconomiques pour les exploitations dans la zone étudiée. L'IGP "Cordero de
Segura y la Sagra" pourrait être utile pour améliorer ces aspects.[EN] The aim of this study is to present the basic characteristics which define the sheep systems in some zones of the PGI Cordero de Segura y la Sagra protected area, in order to bring about actions to improve the competitiveness of such systems. A survey has been conducted among 93 farm owners. The questionnaire included questions regarding herd characteristics, age, educational level, workers, and continuity of the farm activity. The average herd size is 378 animals and the Segureña breed sheep is predominant (99 percent). In 93.5 percent of cases the owner works full time on the farm and the main economic benefit is the sale of lambs for meat, but only 9.7 percent of farmers belong to some kind of marketing cooperative. The average farmer's age is 50 years old and a high percentage (87.1 percent) has no education or a very basic one. The year work unit (YWU) is 1.31 and the work is mainly of family type. In only 12 percent of the cases the continuity of the activity is assured. The above analysed aspects show that it is necessary to achieve better socioeconomic conditions of farms. The PGI Cordero de Segura y la Sagra could be useful to improve these aspects. Therefore we suggest that the PGI must be promoted among farmers, especially among young people.Navarro-Ríos, M.; Marín-Bernal, A.; Martí, A.; Fernández Martínez, CJ. (2011). Characterizacion of Segureña sheep production system in the area of Sierra del Segura y la Sagra, Spain. Options Mediterraneennes. Serie A: Seminaires Mediterraneens. (100):211-216. http://hdl.handle.net/10251/107315S21121610
Low prevalence of chewing lice (Phthiraptera) in wintering populations of the reed bunting Emberiza schoeniclus (Aves: Passeriformes: Emberizidae) in the Iberian Peninsula
The reed bunting is a passerine bird of the Palearctic region, some subspecies suffer a decline in their
populations. Four species of lice have been cited in reed bunting, but lice studies have not been carried out in the Iberian
Peninsula. Between 2018 and 2020 a wintering population of the reed bunting is sampled in the center of the Iberian
Peninsula through mist nets. Lice were collected directly from birds by a visual body examination. Of the 208 reed
buntings sampled, only four individuals were parasitized. We find two species: Menacanthus chrysophaeus, which is
the first record in Iberian lice, and Brueelia blagovescenskyi. Lice are not associated with the sex or age of the birds.
The prevalence obtained is low compared to other European populations. This difference can be explained by the
phenology of the subspecies, the migratory populations have a lower load of lice than sedentary population
Modelos logísticos estocásticos aplicados a la cadena de suministro: una revisión de la literatura
Context: The analysis of the complexity of the systems involves the evolution of the models that representation of reality, logistics has advanced from a business context to the supply chain, basic models of logistics with deterministic parameters must go represent real behavior, stochastic. In this context, the combination of inventory, location and routing models with a stochastic approach applied to supply chains appears.
Method: A systematic review of the literature was developed in the bibliographic databases, ScienceDirect, ScholarGoogle, SpringerLink, Scopus, SemanticScholar, ResearchGate and Scielo, of the 72 referenced articles, 65 % between 2015 and 2019.
Results: From the models identified and described, a taxonomy of the models is proposed and classified into 4 kinds, three dyadic models Location Inventory Problem (LIP), Inventory Routing Problem (IRP), Location Routing problem (LRP) and a triadic model Location Inventory Routing Problem (LIRP). The stochastic parameters used in the models, the types of models, the solution methods, the contemplated objective functions, and the number of echelons in the supply chain are established, from which taxonomies of the different types of models are proposed. Lines of work for future research is presented.
Conclusions: The evolution from deterministic to stochastic models represents an increase in complexity which forces the development of new solution methods with ability to find feasible solutions. The development of models with news measurements of performance as environmental, social and humanitarian have been of recent interest. In the last period, triadic multi-product and multi-period models take on relevance.Contexto: El análisis de la complejidad de los sistemas conlleva la evolución de los modelos de representación de la realidad, la logística ha avanzado de un contexto empresarial a la cadena de suministro, los modelos básicos de logística con parámetros determinísticos requieren representar el comportamiento real estocástico. En este sentido, aparecen la combinación de los modelos de inventario, la localización y el ruteo con enfoque estocástico aplicados a cadenas de suministro.
Método: Se desarrolló una revisión sistemática de la literatura en las bases de datos bibliográficas ScienceDirect, ScholarGoogle, SpringerLink, Scopus, SemanticScholar y Scielo, así como en ResearchGate. De los 79 artículos referenciados, el 65 % comprenden entre el 2015 y 2019.
Resultados: Se identifican y describen los modelos, a partir de lo cual se propone una taxonomía en cuatro combinaciones, tres de modelos diádicos: LIP, IRP, LRP y un modelo tríadico: LIRP. Se identifican los parámetros estocásticos utilizados en los modelos, los tipos de modelos, los métodos de solución, las funciones objetivo contempladas y el número de eslabones de la cadena contemplados, a partir de los cuales se proponen taxonomías de los diferentes tipos de modelos. Por último, se presentan líneas de trabajo para futuras investigaciones.
Conclusiones: La evolución de modelos determinísticos a estocásticos representa un incremento en la complejidad, lo que obliga a desarrollar nuevos métodos de solución con capacidad de encontrar soluciones factibles. Ha sido de reciente interés el desarrollo de modelos y problemas con medidas de desempeño ambiental, social y riesgo humanitario, en el último periodo toman relevancia modelos tríadicos multiproducto y multiperiodo
Modelos logísticos estocásticos: una revisión de la literatura
The present article is done with the aim of to establish the state of the art of location, inventory and routing models with stochastic parameters. The literature reviewed was classified with an operations research approach. A systematic review of the literature in the databases ScienceDirect, ScholarGoogle, SpringerLink, Scopus, SemanticScholar, Scielo, and ResearchGate was done. Through guiding questions, 99 articles were selected, of which 74% is recent literature between 2015 and 2019. Stochastic logistic individual models were classified, a taxonomy with an operations research approach was proposed, from their characteristics, parameters, restrictions, the objective functions and solution methods used. Also, the trends and the future lines of research were identified. As a conclusion new strategies and operating policies that permit improve supply chain performance are identified, also the absence of efficient solution methods has been evident to large instances, according to real-life.El presente artículo se realiza con el objetivo de establecer el estado del arte de los modelos de localización, inventario y ruteo con parámetros estocásticos. Se realizó una revisión sistemática de la literatura en las bases de datos ScienceDirect, ScholarGoogle, SpringerLink, Scopus, SemanticScholar, Scielo y ResearchGate. A través de preguntas orientadoras, se seleccionaron 99 artículos, de los cuales el 74% es literatura reciente entre 2015 y 2019. Se clasificaron los modelos individuales logísticos estocásticos, se propuso una taxonomía con un enfoque de investigación de operaciones, a partir de sus características, parámetros, restricciones, funciones objetivo y métodos de solución utilizados. Asimismo, se identificaron las tendencias y las futuras líneas de investigación. Como conclusión se identifican nuevas estrategias y políticas operativas que permiten mejorar el desempeño de la cadena de suministro, igualmente la ausencia de métodos de solución eficientes ha sido evidente en grandes instancias, según la vida real
El impacto del cumplimiento de los ODS por parte de las empresas de la industria textil
El sector textil se ha convertido en los últimos años en uno de los más importantes a nivel económico y en expansión. Sin embargo, a pesar de las oportunidades que produce, genera grandes impactos negativos, por ejemplo, el sistema empresarial del fast fashion o moda rápida, talleres clandestinos con explotación laboral, la contaminación de ríos o las enfermedades en los trabajadores debido a las sustancias tóxicas son algunos de los factores que salpican este oficio. Debido a esto, se ha convertido en la segunda industria más contaminante del mundo, cuyos residuos son tan perjudiciales para el medioambiente como para la sociedad. Dada la repercusión que tiene hoy en día la palabra “ODS”, este trabajo se propone investigar el papel que adoptan las empresas en el camino hacia la consecución de estos, habiendo escogido el IBEX 35, por ser el índice de referencia de la Bolsa Española y el Mercado Continuo. Teniendo en cuenta lo anterior, el presente trabajo tiene como objetivo estudiar la prevalencia de los objetivos de desarrollo sostenible en la industria textil. Para realizarlo, se procederá a analizar el impacto medioambiental y social que ha provocado el sector textil a lo largo de su historia mostrando la realidad que causa el consumo desmedido.Paralelamente, se investigará cuáles son los objetivos de desarrollo sostenible (ODS) más concluyentes en la industria y seguido, se elaborará un análisis de cada una de las empresas seleccionadas anteriormente.<br /
Stability and Thermal Properties Study of Metal Chalcogenide-Based Nanofluids for Concentrating Solar Power
Nanofluids are colloidal suspensions of nanomaterials in a fluid which exhibit enhanced thermophysical properties compared to conventional fluids. The addition of nanomaterials to a fluid can increase the thermal conductivity, isobaric-specific heat, diffusivity, and the convective heat transfer coefficient of the original fluid. For this reason, nanofluids have been studied over the last decades in many fields such as biomedicine, industrial cooling, nuclear reactors, and also in solar thermal applications. In this paper, we report the preparation and characterization of nanofluids based on one-dimensional MoS2 and WS2 nanosheets to improve the thermal properties of the heat transfer fluid currently used in concentrating solar plants (CSP). A comparative study of both types of nanofluids was performed for explaining the influence of nanostructure morphologies on nanofluid stability and thermal properties. The nanofluids prepared in this work present a high stability over time and thermal conductivity enhancements of up to 46% for MoS2-based nanofluid and up to 35% for WS2-based nanofluid. These results led to an increase in the efficiency of the solar collectors of 21.3% and 16.8% when the nanofluids based on MoS2 nanowires or WS2 nanosheets were used instead of the typical thermal oil
Behavior and performance of BIM users in a collaborative work environment
Collaborative work in Building Information Modeling (BIM) projects is frequentlyunderstood as the interaction of modelers in an asynchronous way through modification requests orvia e-mail/telephone. However, alternative work methodologies based on creating a common andsynchronous environment allow solving issues instantaneously during the design process. This studyaimed to analyze the behavior and performance of BIM users with different specialties who weresubjected to an experimental exercise in a collaborative environment. For this purpose, a processwas devised to collect, sort, and select the data from the log files generated by the BIM software.A timeline of the experiment was populated with data on the intensity and types of commands usedby each specialist, which allowed determining behavioral patterns, preferred commands, indicators oftheir experience, further training needs, and possible strategies for improving the team’s performance.In the experiment, the mechanical designer ’s performance was 49% and the rest approximately 64%,with respect to that of the architect. An average rate of 1.66 necessary or auxiliary commands foreach contributory command was detected. The average performance was 200–400 commands perhour, which intensified by the end of the experiment. Further training needs were detected for theplumbing designer to reduce the use of backwards commands. Conversely, the electrical designershowed a positive evolution regarding this aspect during the experiment. The analysis methods heredescribed become useful for the aforementioned purposes. Nevertheless, combinations with methodsfrom existing research might improve the outcomes and therefore the specificity of recommendation
Torque de desinserción y propiedades fisico-químicas de implantes dentales grabados con ácidos fluorhídrico y nítrico: estudio experimental en perros Beagle
Objetivo: Estudiar la composición, características superficiales y respuesta al torque de desinserción de una superficie implantaria tratada inicialmente con ácido fluorhídrico y posterior pasivado con ácidos fluorhídrico y nítrico.
Diseño del estudio: En una primera fase, se seleccionaron 12 implantes en los que se estudiaron las características fisico-químicas mediante mediciones de energía dispersa de rayos X (EDS), microscopio electrónico de barrido y análisis de XPS (espectrometría de fotoelectrones). Asimismo, se colocaron 24 implantes 'doce de 8 mm y doce de 10 mm de longitud-, en seis perros beagle, en los que tras un período de reposo, se procedió a la retirada de 12 implantes a las seis semanas y los 12 restantes a las doce semanas, mediante un calibrador de torque Gauge TonichiR modelo BGT150CN-S -con un rango de registro de fuerza de 0 a 150 Ncm.
Resultados: El análisis de la composición química superficial mediante EDS sólo mostró la presencia de titanio en las superficies grabadas. En el análisis mediante XPS, al igual que sucede con las superficies de otros implantes dentales, aparecieron trazas de otros elementos presentes en la superficie, fundamentalmente de carbono.
La morfología de la superficie tras el doble grabado con ácido, permitió observar la rugosidad creada por el ataque ácido, con una morfología bastante homogénea. Los valores de rugosidad obtenidos fueron superiores al micrómetro.
Los valores medios encontrados para el torque de desinserción, a las seis semanas, fueron de 79,7 Ncm para los implantes de 8 mm de longitud y 115 Ncm para los implantes de 10 mm. A las doce semanas, estos valores incrementaron hasta 101,2 Ncm para los implantes de 8 mm y 139,7 Ncm para los implantes de 10 mm de longitud.
Conclusiones: El grabado con ácido fluorhídrico y nítrico, posee características superficiales óptimas y comparables al de otras superficies. Los valores de torque de desinserción abren la posibilidad para su aplicación en clínica humana para procedimientos de carga precoz o inmediata.Objective: To study the composition, surface characteristics and response to removal torque of an implant surface subjected to hydrofluoric acid etching and posterior passivating with hydrofluoric and nitric acid.
Study design: Twelve implants were initially selected and their physico-chemical characteristics were evaluated by means of energy-dispersive X-rays (EDS), scanning electron microscopy (SEM) and photoelectron spectroscopy (XPS). In addition, 24 implants ' 12 measuring 8 mm and 12 measuring 10 mm in length ' were implanted in 6 Beagle dogs. Twelve implants were removed after a recovery period of 6 weeks, followed by removal of the remaining 12 implants after 12 Medeweeks,
using a torque calibrator (Gauge Tonichi® model BGT150CN-S) with a force registry range of 0-150 Ncm.
Results: EDS analysis of the surface chemical composition only revealed the presence of titanium in the etched surfaces. In the same way as with the surfaces of other dental implants, XPS analysis revealed traces of other elements present in the surface, fundamentally carbon. Following dual acid etching, the surface showed the roughness resulting from acid action, with a morphology that proved to be quite homogeneous. The roughness values obtained exceeded 1 ìm. The mean removal torque values after 6 weeks were 79.7 Ncm for the 8 mm implants and 115 Ncm for the 10 mm implants. After 12 weeks, these values increased to 101.2 Ncm and 139.7 Ncm, respectively.
Conclusions: Hydrofluoric and nitric acid etching affords optimum surface characteristics comparable to those of other surfaces. The recorded removal torque values raise the possibility of human clinical application for early or immediate loading procedures
Commercial gilthead seabream (Sparus aurata L.) from the Mar Menor coastal lagoon as hotspots of microplastic accumulation in the digestive system
This paper presents the results on the presence and characterization of microplastics (MP) in the gastrointestinal tract of gilthead seabream (Sparus aurata L.), a species of commercial interest from the Mar Menor coastal lagoon in Southeast Spain. This is the first time that microplastic ingestion is recorded in any species from this semi-enclosed bay. Stomach and intestine from a total of 17 specimens captured by local fishermen were processed, and microplastic particles and fibers found in all of them were displayed. Overall, 40.32% (279/692) of total isolated microparticles proved to be microplastics; i.e., <5 mm, as identified by FTIR spectroscopy. The average value by fish was 20.11 _ 2.94 MP kg1, corresponding to average concentrations of 3912.06 _ 791.24 and 1562.17 _ 402.04 MP by kg stomach and intestine, respectively. Four MP forms were isolated: fiber (71.68%), fragment (21.15%), film (6.81%), and microbead (0.36%), with sizes ranging from 91 _m to 5 mm, an average of 0.83 _ 0.04 mm, and no statistically significant differences between mean sizes in stomach and intestine samples (F-test = 0.004; p = 0.936). Nine polymer types were detected, although most of fibers remained unidentified because of their small size, the presence of polymer additives, or closely adhered pollutants despite the oxidizing digestion carried out to eliminate organic matter. No significant correlation was found between main biological parameters and ingested microplastics, and high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene polypropylene (PEP), and polyvinyl (PV) were identified as the most abundant polymers. The average microplastic ingestion in this study area was higher than those reported in most studies within the Mediterranean Sea, and closely related to microplastic pollution in the surrounding area, although with a predominance of fiber form mainly due to fishery activities.This work was financed by Project 5345/18IQA (Technical University of Cartagena). Analyses carried out by Sonia Olmos were supported by a grant from Fundación Séneca (20268/FPI/17)
Aplicación de la teledetección a la cuantificaciónde la defoliación provocada por Lymantria dispar (Linnaeus, 1758) en el Parque Natural de Los Alcornocales (Cádiz, España)(Lepidoptera: Erebidae)
Se calcula el alcance y la gravedad de la defoliación provocada por Lymantria dispar (Linnaeus, 1758) en el Parque Natural de Los Alcornocales (Cádiz, España) en la primera mitad de la década de los 90 mediante el uso de imágenes Landsat-4 desde 1990 hasta 1998. El daño forestal se cuantificó a través de las diferencias del índice de humedad de diferencia normalizada (NDMI) de las imágenes de los años con defoliación (1994 y 1995) y los años previos a la defoliación (1990 a 1993). Los resultados, obtenidos muestran un patrón similar en la distribución del daño con otros estudios, donde las zonas con un mayor grado de defoliación se encuentran alrededor de las áreas urbana
- …