638 research outputs found

    Distance-Based Methods: Ripley’s K function vs. K density function

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    In this paper, we propose an analytical and methodological comparison between two of the most known distance-based methods in the evaluation of the geographic concentration of economic activity. These two methods are Ripley’s K function, a cumulative function popularised by Marcon and Puech (2003) that counts the average number of neighbours of each point within a circle of a given radius, and K density function, a probability density function of point-pair distances introduced by Duranton and Overman (2005), which considers the distribution of distances between pairs of points. To carry out this comparison, we first apply both methodologies to an exhaustive database containing Spanish manufacturing establishments and we evaluate the spatial location patterns obtained from both analysis. After an initial analysis, we realise that although these functions have always been treated as substitutes they should be considered as complementary, as both cumulative function and probability density function provide relevant and necessary information about the distribution of activity in space. Therefore, our next step will be to assess what are the advantages and disadvantages of each methodology from a descriptive and analytical way.

    Mudança tecnológica, eficiência e produtividade total de fatores na agricultura brasileira, 1970-95

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    This study applies a Data Envelopment Analysis (DEA) approach to analyze total factor, technology and efficiency changes in the Brazilian agriculture from 1970 to 1995, in the units of the federation. Malmquist productivity indexes were decomposed into two components: technical change and efficiency change. The results showed the largest productivity growths in the Center-west, Southeast and South regions. Technical progress was the most important factor in the areas of advanced-technology agriculture. Efficiency increases were the main components in areas of low-technology agriculture. The North and Northeast regions presented technical regress

    A Physically-Based Fractional Diffusion Model for Semi-Dilute Suspensions of Rods in a Newtonian Fluid

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    [EN] The rheological behaviour of suspensions involving interacting (functionalized) rods remains nowadays incompletely understood, in particular with regard to the evolution of the elastic modulus with the applied frequency in small-amplitude oscillatory flows. In a previous work, we addressed this issue by assuming a fractional diffusion mechanism, however the approach followed was purely phenomenological. The present work revisits the topic from a phys ical viewpoint, with the aim of justifying the fractional nature of diffusion. After accomplishing this first objective, we explore by means of numerical ex periments the consequences of the proposed fractional modelling approach in linear and non-linear rheology.Nadal, E.; Aguado-López, JV.; Abisset-Chavanne, E.; Chinesta Soria, FJ.; Keunings, R.; Cueto, E. (2017). A Physically-Based Fractional Diffusion Model for Semi-Dilute Suspensions of Rods in a Newtonian Fluid. Applied Mathematical Modelling. 51:58-67. https://doi.org/10.1016/j.apm.2017.06.009S58675

    Definition of Project-Based Learning Models in the Computer Engineering Degree

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    [EN] The current characteristics, concerns, preferences, and interests of students differ greatly from the previous students¿ generations. Nowadays, students are increasingly demanding active methodologies that facilitate their learning process. To meet the actual students¿ requirements, academic research is focused on the definition of educational mechanisms that promote greater students¿ participation. Among these mechanisms, the project-based learning (PBL) is a model that organizes learning around projects. Projects are student-driven and provide more tangible results what has been considered as a positive aspect to deepen and retain knowledge. The main objective of this paper is to describe all the activities performed to plan, define, design and project an integrated PBL model for students in the last years (3rd and 4th year students) of the Computer Engineering Degree. The PBL model involves the following subjects: (i) Software Engineering; (ii) Project Management; (ii) Business Requirements Analysis and (iv) Business Models and Organisation Functional Areas. The PBL model has twofold perspectives, the first one is more project and software-directed while the second one is more businessoriented. This model seeks to give continuity to the teaching-learning process so that students can appreciate greater coherence, links, and succession of the contents of different subjects. Moreover, the definition of the PBL model will also support the enhancement of the horizontal and vertical transversal coordination among different subjects.This article has been supported by the Vice-rectorate for Digital Resources and Documentation (Vicerrectorado de Recursos Digitales y Documentación) and Vice-Rectorate for Studies, Quality and Accreditation (Vicerrectorado de Estudios, Calidad y Acreditación) under the Call for Learning + Teaching (Convocatoria Aprendizaje + Docencia (A+D 2019)) and Project Code: 1678-A. The authors would like to acknowledge the support of the Institute of Educational Sciences (Instituto de Ciencias de la Educación) of Universitat Politècnica de València, the Evaluation and Monitoring Commission for Educational Innovation and Improvement Projects (Comisión de Evaluación y Seguimiento de Proyectos de Innovación y Mejora Educativa - CESPIME) and Escuela Politécnica Superior de AlcoyEsparza Peidro, J.; Golf Laville, EJ.; Izquierdo-Doménech, JJ.; Tomas Miquel, JV.; Sanchis, R. (2020). Definition of Project-Based Learning Models in the Computer Engineering Degree. EDULEARN Proceedings (Internet). 3966-3972. https://doi.org/10.21125/edulearn.2020.1074S3966397

    Ternary solid-ferrofluid-liquid magnetorheological fluids

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    A new kind of magnetorheological fluid is proposed that exhibits both enhanced magnetorheological effect and kinetic stability against sedimentation. It includes the presence of small amounts of an emulsified aqueous ferrofluid as a third phase in a conventional oil-based magnetorheological fluid prepared by the dispersion of carbonyl iron microparticles.This work was supported by MINECO MAT 2016-78778-R and PCIN-2015-051 projects (Spain), the European Regional Development Fund (ERDF) and by the Junta de Andalucía P11-FQM-7074 project (Spain). J J Yang acknowledges the Chinese State Scholarship Fund. J R Morillas acknowledges the FPU14/01576 fellowship

    Harmonization Process and Reliability Assessment of Anthropometric Measurements in the Elderly EXERNET Multi-Centre Study

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    Background: The elderly EXERNET multi-centre study aims to collect normative anthropometric data for old functionally independent adults living in Spain.Purpose: To describe the standardization process and reliability of the anthropometric measurements carried out in the pilot study and during the final workshop, examining both intra- and inter-rater errors for measurements.Materials and Methods: A total of 98 elderly from five different regions participated in the intra-rater error assessment, and 10 different seniors living in the city of Toledo (Spain) participated in the inter-rater assessment. We examined both intra- and inter-rater errors for heights and circumferences.Results: For height, intra-rater technical errors of measurement (TEMs) were smaller than 0.25 cm. For circumferences and knee height, TEMs were smaller than 1 cm, except for waist circumference in the city of Ca´ceres. Reliability for heights and circumferences was greater than 98% in all cases. Inter-rater TEMs were 0.61 cm for height, 0.75 cm for knee-height and ranged between 2.70 and 3.09 cm for the circumferences measured. Inter-rater reliabilities for anthropometric measurements were always higher than 90%.Conclusion: The harmonization process, including the workshop and pilot study, guarantee the quality of the anthropometric measurements in the elderly EXERNET multi-centre study. High reliability and low TEM may be expected when assessing anthropometry in elderly population.SIThe elderly EXERNET multi-centre study has been supported by the Ministerio de Trabajo y Asuntos Sociales (104/07), Universidad de Zaragoza (UZ 2008-BIO-01) and Ministerio de Sanidad, Servicios Sociales e Igualdad (147/2011). A. Go´ mez-Cabello has received a PhD grant from the Gobierno de Aragon (B059/ 09). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    The Mediating Role of Brown Fat and Skeletal Muscle Measured by 18F-Fluorodeoxyglucose in the Thermoregulatory System in Young Adults

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    The authors would like to thank all the participants who took part in this investigation. This study is part of a PhD thesis conducted in the Biomedicine Doctoral Studies of the University of Granada, Spain. We are grateful to Alberto Quesada-Aranda for helping with the development of the Temperatus software (free trial at http://profith.ugr.es/ temperatus?lang=en). We are grateful to Ms Carmen Sainz-Quinn for assistance with English-language editingObjective: This study aimed to examine whether brown adipose tissue (BAT) or skeletal muscle activity mediates the relationship between personal level of environmental temperature (Personal-ET) and wrist skin temperature (WT). Moreover, we examined whether BAT and skeletal muscle have a mediating role between Personal-ET and WT (as a proxy of peripheral vasoconstriction/vasodilation). Methods: The levels of BAT were quantified by cold-induced 18F-fluorodeoxyglucose–positron emission tomography/computed tomography scan and measured the Personal-ET and WT by using iButtons (Maxim Integrated, Dallas, Texas) in 75 participants (74.6% women). Results: The study found that BAT volume and metabolic activity played a positive and significant role (up to 25.4%) in the association between Personal-ET and WT. In addition, at the coldest temperatures, the participants with lower levels of WT (inducing higher peripheral vasoconstriction) had higher levels of BAT outcomes, whereas in warm temperatures, participants with higher levels of WT (inducing higher peripheral vasodilation) had lower levels of BAT outcomes. The study did not find any mediating role of skeletal muscle activity. Conclusions: BAT volume and metabolic activity play a role in the relationship between Personal-ET and WT. Moreover, the data suggest that there are two distinct phenotypes: individuals who respond better to the cold, both through nonshivering thermogenesis and peripheral vasoconstriction, and individuals who respond better to the heat.This study was supported by the Spanish Ministry of Economy and Competitiveness, Fondo de Investigación Sanitaria del Instituto de Salud Carlos III (PI13/01393), Retos de la Sociedad (DEP2016‐79512‐R), and Fondos Estructurales de la Unión Europea (FEDER); by the Spanish Ministry of Education (FPU 13/04365); by the Fundación Iberoamericana de Nutrición; by the Redes Temáticas de Investigación Cooperativa RETIC (Red SAMID RD16/0022); by AstraZeneca HealthCare Foundation; by the University of Granada, Plan Propio de Investigación 2016, Excellence actions: Units of Excellence; Unit of Excellence on Exercise and Health (UCEES); and by the Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades and European Regional Development Fund (ERDF), ref. SOMM17/6107/UGR, Programa Contratos‐Puente. MAR is supported by a predoctoral research grant from University Jaume I (PREDOC/2015/13). AMN was supported by the Ministry of Economy and Competitiveness, the Instituto de Salud Carlos III through the Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CB16/10/00239), and grant 19899/GERM/15 (cofinanced by FEDER)

    A High-Throughput Screening Plattform of Microbial Natural Products for the Discovery of Moleculaes with Antibiofilm Properties against Salmonella

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    In this report, we describe a High-Throughput Screening (HTS) to identify compounds that inhibit biofilm formation or cause the disintegration of an already formed biofilm using the Salmonella Enteritidis 3934 strain. Initially, we developed a new methodology for growing Salmonella biofilms suitable for HTS platforms. The biomass associated with biofilm at the solid-liquid interface was quantified by staining both with resazurin and crystal violet, to detect living cells and total biofilm mass, respectively. For a pilot project, a subset of 1120 extracts from the Fundación MEDINA's collection was examined to identify molecules with antibiofilm activity. This is the first validated HTS assay of microbial natural product extracts which allows for the detection of four types of activities which are not mutually exclusive: inhibition of biofilm formation, detachment of the preformed biofilm and antimicrobial activity against planktonic cells or biofilm embedded cells. Currently, several extracts have been selected for further fractionation and purification of the active compounds. In one of the natural extracts patulin has been identified as a potent molecule with antimicrobial activity against both, planktonic cells and cells within the biofilm. These findings provide a proof of concept that the developed HTS can lead to the discovery of new natural compounds with antibiofilm activity against Salmonella and its possible use as an alternative to antimicrobial therapies and traditional disinfectants
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