152,773 research outputs found

    Desarrollo de papeles biocativos por injerto de mol茅culas espec铆ficas en celulosa

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    Tesis (DCI)--FCEFN-UNC, 2019En la presente tesis se presenta el desarrollo de papeles bioactivos con potencial aplicaci贸n en el envasado activo de alimentos. Para tal fin, se propuso el injerto de eugenol, un compuesto de origen natural con propiedades antimicrobiana, antioxidante y repelente de insectos, en celulosa, utilizando 谩cido policarbox铆lico como agente ligante. Con el objetivo de evaluar la escalabilidad del proceso propuesto, se estudiaron distintas tecnolog铆as de curado, tales como calentamiento por convecci贸n, infrarrojo, microondas y conducci贸n. En todos los casos, se analizaron la influencia de las variables operativas sobre el avance de la reacci贸n y propiedades finales del papel preparado, utilizando un dise帽o de experimentos Doehlert para elegir las experiencias a realizar, y analizando los resultados mediante metodolog铆a de superficie de respuesta y an谩lisis estad铆stico ANOVA. Se pudo comprobar que la reacci贸n de injerto de eugenol en papel comercial se produjo con 茅xito en todas las tecnolog铆as estudiadas. Asimismo, se encontraron las condiciones 贸ptimas de reacci贸n para cada una de las tecnolog铆as, para lo cual se busc贸 un compromiso entre el avance de la reacci贸n y las propiedades finales del material (mec谩nicas y color). A partir de estas condiciones, se prepararon papeles y se realiz贸 una caracterizaci贸n m谩s espec铆fica para su aplicaci贸n como envase de alimentos comparando los papeles modificados con el papel virgen. Se analizaron las propiedades mec谩nicas por ensayo de tracci贸n, rasgado y punzonado y se midi贸 la absorci贸n de agua y la capacidad de degradaci贸n. Por otro lado, las propiedades bioactivas analizadas fueron la actividad antioxidante, antimicrobiana, repelente e insecticida de gorgojos (T. castaneum y R. dominica). Una vez probado que el papel modificado presenta buenas caracter铆sticas f铆sicas y bioactivas para su posible aplicaci贸n en el envasado de alimentos, se realizaron prototipos de envasado para harina, como alimento representativo de alimentos derivados de cereales, susceptibles al ataque de plagas. En este estudio se analiz贸 la migraci贸n de reactivos, propiedades organol茅pticas y conservaci贸n del alimento, arrojando resultados promisorios para la industria de envases de alimentos. Finalmente, se realiz贸 una comparaci贸n de las tecnolog铆as de curado ensayadas, analizando diferentes aspectos como avance de reacci贸n, propiedades finales, apariencia, tiempo de reacci贸n, consumo de energ铆a, entre otros, como as铆 tambi茅n disponibilidad y uso de estas tecnolog铆as a escala industrial, seleccionando la tecnolog铆a de conducci贸n como la m谩s adecuada para una propuesta de escalado industrial.Fil: Muratore, Florencia. Universidad Nacional de C贸rdoba. Facultad de Ciencias Exactas, F铆sicas y Naturales; Argentina.Fil: Muratore, Florencia. Consejo Nacional de Investigaciones Cient铆ficas y T茅cnicas. Instituto de Investigaci贸n y Desarrollo en Ingenier铆a de Procesos y Qu铆mica Aplicada; Argentina

    Does international patent collaboration have an effect on entrepreneurship?

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    .Entrepreneurship is one of the main pillars of growth in any economy. Achieving a high rate of entrepreneurship in a region has become the priority objective of governments and firms. However, in many cases, new firm creation is conditioned by relations or collaboration in innovation with agents from other countries. Previous literature has analyzed the mechanisms that foster entrepreneurship. This paper attempts to shed light on the influence of international patent collaboration (IPC) on entrepreneurial activity at country level taking into account the timing of this relationship. An empirical study is proposed to verify whether IPC leads to greater entrepreneurship and to analyze the gestation period between international patenting actions and firm creation. Using the Generalized Method of Moments, the two hypotheses proposed were tested in a data panel of 30 countries for the period 2005鈥2017. Results show the influence of IPC in promoting entrepreneurship in the same year, but especially in the following year. The study offers implications for entrepreneurs and public agents. IPC affects the integration and interaction of international agents in a country, favors the production of new knowledge, and increases positive externalities in a territory. All this facilitates the creation of new companies with a high innovative component.S

    Confesiones religiosas y fiscalidad local = Religious confessions and local taxation

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    La evoluci贸n de la sociedad espa帽ola ha provocado que las medidas fiscales adoptadas a favor de las confesiones religiosas, en particular, de la Iglesia Cat贸lica, generen un debate pol铆tico y social sobre las posibilidades de una reforma en este 谩mbito. Este debate en torno a los beneficios fiscales aprobados a favor de las confesiones religiosas ha generado y genera numerosos debates que, en ocasiones, exceden la esfera puramente jur铆dica. Sin embargo, el examen legal de esta cuesti贸n no solo no se puede obviar, sino que debe ser el goce de un car谩cter esencial. En este sentido, estas entidades, en virtud de diferentes Acuerdos de cooperaci贸n y de otra normativa aplicable al efecto, se encuentran exentas de manera total o parcial respecto a algunos tributos, muchos de ellos parte del sistema tributario local. Estos tributos han generado numerosos problemas en lo que su aplicaci贸n se refiere, derivados fundamentalmente de la concurrencia de distintos textos normativos que inciden sobre esta cuesti贸n. No obstante, la pertenencia de Espa帽a a la Uni贸n Europea y la necesaria observancia del Derecho Comunitario genera nuevos interrogantes que pueden conducir a una verdadera reformulaci贸n de los beneficios fiscales vigentes para las confesiones religiosas. Es por ello que en este estudio se analizar谩n la procedencia de esas exenciones, desgranaremos la raz贸n de su concesi贸n y examinaremos las posibilidades para su pervivencia

    An谩lisis de la calidad del servicio que prestan las entidades bancarias y su repercusi贸n en la satisfacci贸n del cliente y la lealtad hacia la entidad

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    p. 79-107El objetivo de la investigaci贸n se ha encuadrado en determinar las percepciones de calidad que tienen los clientes sobre su entidad bancaria. Para ello, para contrastar el modelo se han utilizado ecuaciones estructurales por medio de m铆nimos cuadrados parciales conocido como PLS (Partial Least Square). El objetivo concreto ha sido analizar los factores que determinan la calidad del servicio que perciben los clientes de las entidades bancarias, entre los que se encuentran: i) aspecto operativo, ii) aspecto f铆sico, iii) nuevas tecnolog铆as, y iv) aspecto humano. Una vez determinada la fiabilidad y validez de la escala, se procedi贸 a verificar las tres hip贸tesis de la investigaci贸n. La primera hip贸tesis del modelo examina cada una de las relaciones de estos factores con la calidad del servicio, del que se resalta la gran influencia de los aspectos operativos en la percepci贸n de la calidad. La segunda hip贸tesis demuestra que la calidad del servicio es un antecedente de la satisfacci贸n del cliente. Y una tercera hip贸tesis verifica que la satisfacci贸n del cliente tiene influencia en la lealtad del cliente hacia la entidad.S

    Application of lactic acid bacteria for the biopreservation of meat products: A systematic review

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    .The increasing concern of consumers about food quality and safety and their rejection of chemical additives has promoted the breakthrough of the biopreservation field and the development of studies on the use of beneficial bacteria and their metabolites as potential natural antimicrobials for shelf life extension and enhanced food safety. Control of foodborne pathogens in meat and meat products represents a serious challenge for the food industry which can be addressed through the intelligent use of bio-compounds or biopreservatives. This article aims to systematically review the available knowledge about biological strategies based on the use of lactic acid bacteria to control the proliferation of undesirable microorganisms in different meat products. The outcome of the literature search evidenced the potential of several strains of lactic acid bacteria and their purified or semi-purified antimicrobial metabolites as biopreservatives in meat products for achieving longer shelf life or inhibiting spoilage and pathogenic bacteria, especially when combined with other technologies to achieve a synergistic effect.S

    How Does Reciprocity Affect Undergraduate Student Orientation towards Stakeholders?

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    5987Nowadays, students are more aware of the impact of companies on their stakeholders and the need for properly handling their expectations to operationalize corporate social responsibility. Nevertheless, little is known about how certain individual traits may relate to their stance on the issue. This exploratory research contributes to stakeholder theory by analysing the e ect of the individual鈥檚 decision-making process, including the consideration of their social preferences, on their orientation toward stakeholder management. Here, we draw upon a theoretical model for resource-allocation decision-making consisting of reciprocal and non-reciprocal components. Our data, from undergraduate students enrolled in di erent degrees, were collected through a questionnaire and two social within-subject experiments (ultimatum and dictator games). Thus, our results show that the presence of a reciprocal component when decisions are made is positively linked to an instrumental orientation toward stakeholders. In addition, a greater non-reciprocal component in the decision-making process corresponds to a more normative orientation.S

    Analysis of reliable deployment of TDOA local positioning architectures

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    .Local Positioning Systems (LPS) are supposing an attractive research topic over the last few years. LPS are ad-hoc deployments of wireless sensor networks for particularly adapt to the environment characteristics in harsh environments. Among LPS, those based on temporal measurements stand out for their trade-off among accuracy, robustness and costs. But, regardless the LPS architecture considered, an optimization of the sensor distribution is required for achieving competitive results. Recent studies have shown that under optimized node distributions, time-based LPS cumulate the bigger error bounds due to synchronization errors. Consequently, asynchronous architectures such as Asynchronous Time Difference of Arrival (A-TDOA) have been recently proposed. However, the A-TDOA architecture supposes the concentration of the time measurement in a single clock of a coordinator sensor making this architecture less versatile. In this paper, we present an optimization methodology for overcoming the drawbacks of the A-TDOA architecture in nominal and failure conditions with regards to the synchronous TDOA. Results show that this optimization strategy allows the reduction of the uncertainties in the target location by 79% and 89.5% and the enhancement of the convergence properties by 86% and 33% of the A-TDOA architecture with regards to the TDOA synchronous architecture in two different application scenarios. In addition, maximum convergence points are more easily found in the A-TDOA in both configurations concluding the benefits of this architecture in LPS high-demanded applicationS

    What is the importance of sperm subpopulations?

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    .The study of sperm subpopulations spans three decades. The origin, meaning, and practical significance, however, are less clear. Current technology for assessing sperm morphology (CASA-Morph) and motility (CASA-Mot) has enabled the accurate evaluation of these features, and there are many options for data classification. Subpopulations could occur as a result of the stage of development of each spermatozoon in the subpopulation. Spermatogenesis might contribute to the production of these subpopulations. Insights from evolutionary biology and recent molecular research are indicative of the diversity among male gametes that could occur from unequal sharing of transcripts and other elements through cytoplasmic bridges between spermatids. Sperm cohorts exiting the gonads would contain different RNA and protein contents, affecting the spermatozoon physiology and associations with the surrounding environmental milieu. Subsequently, these differences could affect how spermatozoa interact with the environmental milieu (maturation, mixing with seminal plasma, and interacting with the environmental milieu, or female genital tract and female gamete). The emergence of sperm subpopulations as an outcome of evolution, related to the reproductive strategies of the species, genital tract structures, and copulatory and fertilization processes. This kind of approach in determining the importance of sperm subpopulations in fertilization capacity should have a practical impact for conducting reproductive technologies, inspiring and enabling new ways for the more efficient use of spermatozoa in the medical, animal breeding, and conservation fields. This manuscript is a contribution to the Special Issue in memory of Dr. Duane GarnerS

    A new index of resilience applicable to external pulse-disturbances that considers the recovery of communities in the short term

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    .Resilience is a key concept in the study of the recovery of ecosystems affected by disturbances. Currently, there are numerous indices to measure resilience, but many of them do not show the accuracy of the resilience value or the behaviour of ecological parameters in the face of disturbances. New approaches and technologies enable large amounts of information to be obtained, facilitating the proposal of new resilience indices that work consistently and intuitively for a wide variety of ecological response variables under different scenarios after pulse-disturbances. In this study, we propose and verify a new resilience index, comparing its performance with others previously published. We validated the performance of the new index using real data based on field measurements of changes in soil bacterial OTUs diversity and abundance after a wildfire. The new resilience index provided an automatic and robust functional classification of the behaviour of ecosystems after disturbances, supported by a bootstrap analysis. We identified 5 scenarios of ecosystem resilience performance according to their behaviour after a pulse-disturbance: resilient, non-resilient, recovering, rebound, and continuing.S

    Calidad percibida del servicio en la cadena de aprovisionamiento en la industria tur铆stica

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    Este trabajo contribuye a relacionar las 谩reas de la gesti贸n de la calidad del servicio y la gesti贸n de la cadena de aprovisionamiento. M谩s concretamente, permite comprender mejor c贸mo la gesti贸n de la calidad del servicio puede ayudar a describir, explicar y predecir los resultados en la cadena de aprovisionamiento. Se analizan qu茅 factores son importantes considerar en la calidad percibida del servicio de la cadena de aprovisionamiento y c贸mo influyen 茅stos en la futura relaci贸n comprador-proveedor. Para ello, se desarrolla y verifica un modelo incorporando constructos tales como desempe帽o del servicio, calidad del servicio percibida, satisfacci贸n y lealtad. La literatura aporta trabajos de estos constructor en la relaci贸n empresa-cliente final y comprador-vendedor en empresas manufactureras, pero existe una laguna en la relaci贸n entre miembros de de la cadena de aprovisionamiento en empresas de servicios. Por ello, el modelo fue verificado con 908 evaluaciones que realizaron los gerentes de establecimientos hoteleros sobre la calidad percibida del servicio del proveedor. El an谩lisis de los datos soporta el modelo conceptual donde la satisfacci贸n y la lealtad de los gerentes de los hoteles al proveedor est谩 muy influenciada por la calidad del servicio que recibe de 茅ste
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