785 research outputs found

    Urban logistics solutions in Latin America a study of a modern commercially dense neighborhood in the City of Quito-Ecuador

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    Population in Latin America has been increasing its growth rate through the years. As the cities expand and people move to urban areas, businesses have to struggle with major logistics challenges and rely heavily on timely and effective deliveries of resources in order to cope with consumer demand. The city of Quito, in Ecuador, is currently facing the logistic challenges mentioned above. To address these logistical challenges, concepts and techniques of urban logistics are proposed and developed in the literature. The objective of this paper is to understand the loading and unloading logistic activities in one of the most commercially dense neighborhoods in the city of Quito called “La Mariscal”. An optimization model was used to determine the number of loading & unloading bays, and their optimal location, that should be implemented with the goal of enabling transportation companies to transport and deliver resources in a more efficient and effective way. This investigation is part of a bigger urban logistics project in Quito that is currently being led by Universidad San Francisco de Quito (USFQ), with the support of the MIT Megacity Logistics Lab (MIT MLL). This project aims to propose solutions to major urban logistics challenges using the Urban Logistics Atlas methodology developed by MIT MLL. As the following paper shows, with urban logistics solutions, simulation and optimization models, it is possible to make cities in Latin America become more mobile, sustainable and above all, livable.La población en América Latina ha ido aumentando su tasa de crecimiento a lo largo de los años. A medida que las ciudades crecen y las personas se trasladan a zonas urbanas, las diferentes empresas y negocios tienen que luchar con importantes retos logísticos y dependen en gran medida de la entrega oportuna y eficaz de los recursos para poder cumplir con la demanda de los consumidores. La ciudad de Quito, en Ecuador, actualmente está enfrentando los retos logísticos mencionados anteriormente. Para poder tratar y reducir estos retos logísticos, conceptos y técnicas de logística urbana son propuestos y desarrollados en la literatura. El objetivo de este estudio es entender las actividades logísticas de carga y descarga en uno de los barrios comercialmente más densos en la ciudad de Quito llamado "La Mariscal". Un modelo de optimización fue utilizado para determinar el número de bahías de carga y descarga, y su ubicación óptima, que deberían implementarse con el objetivo de permitir a las empresas de transporte movilizar y entregar los recursos de manera más eficiente y efectiva. Esta investigación es parte de un proyecto de logística urbana más grande que se desarrolla en la ciudad de Quito, y que actualmente está dirigido por la Universidad San Francisco de Quito (USFQ), con el apoyo del Laboratorio de Logística de Mega Ciudades del MIT (MIT MLL). Este estudio tiene como objetivo proponer soluciones a los principales retos de la logística urbana mediante la metodología del Atlas de Logística Urbana desarrollada por el MIT MLL. Como lo muestra el siguiente estudio, con soluciones de logística urbana, modelos de simulación y optimización, es posible hacer que las ciudades en América Latina mejoren su movilidad, se vuelvan más sustentables, y, sobre todo, se vuelvan más habitables

    Un estudio sobre el techo de cristal en el acceso a los puestos de poder en las universidades públicas valencianas (2010-2020)

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    Treball final de Màster Universitari en Igualtat i Gènere en l'Àmbit Públic i Privat (Pla de 2013). Codi: SRM042. Curs acadèmic 2019-2020A study on the glass roof in access to positions of power in Valencian public universities (2010-2020)

    Prym varieties, curves with automorphisms and the Sato Grassmannian

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    Este trabajo trata las variedades de Prym, curvas con automorfismos y Grassmannian de Sato.The aim of the paper is twofold. First, some results of Shiota and Plaza-Martín on Prym varieties of curves with an involution are generalized to the general case of an arbitrary automorphism of prime order. Second, the equations defining the moduli space of curves with an automorphism of prime order as a subscheme of the Sato Grassmannian are given

    Advanced titanium scaffolds obtained by directional freeze-drying: on the influence of processing conditions

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    Ministry of Science and Innovation of Spain under Grant No. MAT2010-20855Junta de Andalucía (Spain) / FEDER (EU), through the project Ref. P12-TEP-140

    Changes in the Polyphenolic Profile and Antioxidant Activity of Wheat Bread after Incorporating Quinoa Flour

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    This research was funded by grant PID2019-107650RB-C21 funded by MCIN/AEI/ 10.13039/501100011033 (Agencia Estatal de Investigacion del Ministerio de Ciencia e Innovacion, Spain), and by grant 119RT0S67 funded by CYTED (Programa Iberoamericano de Ciencia y Tecnologia para el Desarrollo).Quinoa is a trend and a promising functional food ingredient. Following previous research into the impact of incorporating quinoa flour on the polyphenol content and antioxidant activity of bread, this study aimed to bridge an existing gap about the qualitative and quantitative polyphenolic profiles of such bread. The UPLC-MS/MS analysis showed that quinoa bread, made with 25% quinoa flour of a black variety, presented more compounds than refined-wheat bread, and levels were remarkably higher in many cases. Consequently, the quinoa bread presented clearly improved polyphenolic content than the wheat bread (12.8-fold higher considering the sum of extractable and hydrolyzable polyphenols), as supported by greater antioxidant activity (around 3-fold). The predominant compounds in the extractable fraction of quinoa bread were p-hydroxybenzoic acid and quercetin (50- and 64-fold higher than in wheat bread, respectively) and rutin (not detected in wheat bread), while ferulic and sinapic acids were the most abundant compounds in the hydrolyzable fraction (7.6- and 13-fold higher than in wheat bread, respectively). The bread-making impact was estimated, and a different behavior for phenolic acids and flavonoids was observed. Extractable phenolic acids were the compounds that decreased the most; only 2 of 12 compounds were enhanced (p-hydroxybenozoic and rosmarinic acid with increments of 64% and 435%, respectively). Flavonoids were generally less affected, and their concentrations considerably rose after the bread-making process (7 of the 13 compounds were enhanced in the extractable fraction) with especially noticeably increases in some cases; e.g., apigenin (876%), kaempferol (1304%), luteolin (580%) and quercetin (4762%). Increments in some extractable flavonoids might be explained as a consequence of the release of the corresponding hydrolyzable forms. The present study provides new information on the suitability of quinoa-containing bread as a suitable vehicle to enhance polyphenols intake and, hence, the antioxidant activity in daily diets.Agencia Estatal de Investigacion del Ministerio de Ciencia e Innovacion, Spain PID2019-107650RB-C21 MCIN/AEI/ 10.13039/501100011033CYTED (Programa Iberoamericano de Ciencia y Tecnologia para el Desarrollo) 119RT0S6

    Porous Titanium Cylinders Obtained by the Freeze-Casting Technique: Influence of Process Parameters  on Porosity and Mechanical Behavior

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     The discrepancy between the stiffness of commercially pure titanium and cortical bone  tissue compromises its success as a biomaterial. The use of porous titanium has been widely studied,  however, it is still challenging to obtain materials able to replicate the porous structure of the bones  (content, size, morphology and distribution). In this work, the freeze‐casting technique is used to  manufacture cylinders with elongated porosity, using a home‐made and economical device. The  relationship between the processing parameters (diameter and material of the mold, temperature  gradient), microstructural features and mechanical properties is established and discussed, in terms  of ensuring biomechanical and biofunctional balance. The cylinders have a gradient porosity  suitable for use in dentistry, presenting higher Young’s modulus at the bottom, near the cold spot  and, therefore better mechanical resistance (it would be in contact with a prosthetic crown), while  the opposite side, the hot spot, has bigger, elongated pores and walls.  Ministry of Economy and Competitiveness of Spain  grant  MAT2015‐71284‐P  FEDER‐Junta de Andalucía Research  Project (Modeling and implementation of the freeze casting technique: gradients of porosity with a tribomechanical equilibrium and electro‐stimulated cellular behavior).

    Stock Market Synchronization and Stock Volatility: The Case of an Emerging Market

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    Sincronización del mercado de valores y volatilidad de los activos: El caso de un mercado emergente El propósito de este trabajo es estudiar el efecto de la sincronización bursátil sobre la volatilidad de sus activos componentes. Para este objetivo, calculamos la sincronización del mercado de valores utilizando el método de análisis de red de longitud mínima del árbol de expansión (MSTL). Luego, implementamos pruebas de pronóstico dentro y fuera de la muestra para evaluar el poder de pronóstico en la sincronización del mercado de valores para predecir la volatilidad realizada por las acciones individuales. Además, probamos un VAR y un análisis de descomposición de varianza de error de pronóstico para estudiar la presencia de causalidad de Granger en la volatilidad. Nuestros resultados muestran que la sincronización dentro de un mercado existe y cambia con el tiempo. Nuestros principales resultados muestran que un aumento en la sincronización provoca un aumento en la volatilidad realizada de los activos financieros en el mes siguiente. Nuestros resultados permitieron estudiar la sincronización de los mercados financieros y adoptar un enfoque de riesgo sistémico para mejorar la gestión de las inversiones. Nuestra idea principal era que la sincronización de los mercados de valores se correlaciona positivamente con la volatilidad de los activos financieros. Cuanto mayor sea la sincronización, mayor será la volatilidad en el período siguiente. Este estudio ofrece un nuevo enfoque para estudiar la volatilidad del mercado de valores.The purpose of this paper is to study the effect of stock market synchronization on the volatility of its component assets. For this objective, we calculate the stock market's synchronization using the Minimum Spanning Tree Length (MSTL) network analysis method. Then, we implement forecasting tests in and out the sample to assess the forecasting power on the stock market's synchronization to predict the individual stock realized volatility. Additionally, we test a VAR and a forecast error variance decomposition analysis to study Granger causality's presence on volatility. Our results show that synchronization within a market exists and changes over time. Our main results show that an increase in synchronization causes an increase in financial assets' realized volatility in the following month. Our results made it possible to study financial markets' synchronization and take a systemic risk approach to improve investment management. Our main idea was that the stock markets' synchronization positively correlates with financial assets' volatility. The greater the synchronization, the greater the volatility in the following period. This study offers a new approach to study the stock market volatility

    Constraints on the Abundance of Primordial Black Holes from X-Ray Quasar Microlensing Observations: Substellar to Planetary Mass Range

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    We thank the anonymous referee for the valuable comments that helped improve this paper. This research was supported by the Spanish projects PID2020-118687GB-C33, PID2020-118687GB-C32 and PID2020-118687GB-C31 financed by MCIN/AEI/10.13039/501100011033. J.J.V. is also supported by projects FQM-108, P20_00334 and A-FQM-510-UGR20/FEDER financed by Junta de Andalucía. J.A.M. is also supported by the Generalitat Valenciana with the project of excellence Prometeo/2020/085. A.E.G. thanks the support from grant FPI-SO from the Spanish MINECO (research project SEV-2015-0548-17-4 and predoctoral contract BES-2017-082319) and acknowledges support from ANID Fondecyt Postdoctorado with grant No. 3230554.We use X-ray observations of quasar microlensing (sensitive to smaller compact objects than in the optical) to study the possible presence of a population of low mass black holes (BHs; from ∼10−3 M ⊙ to 10−1 M ⊙) in lens galaxies. We compare these observations with microlensing magnification simulations of a mixed population of stars and BHs plus a smooth matter component. We estimate the individual mass fractions of both stars and BHs for three different BH masses in the range of substellar to planetary masses. Our Bayesian analysis indicates that the contribution of BHs is negligible in the substellar mass range but that a population of BHs of planetary mass (M ≲ 10−3 M ⊙) could pass unnoticed to X-ray microlensing. We provide new upper limits to the contribution of BHs to the fraction of dark matter based on both, the quasar microlensing data in the X-ray band, and our previous estimates in the optical of intermediate-mass BHs with an additional upper limit at M = 3M ⊙MCIN/AEI/10.13039/501100011033: PID2020-118687GB-C33, PID2020-118687GB-C32, PID2020-118687GB-C31Junta de Andalucía FQM-108, P20_00334, A-FQM-510-UGR20/FEDERGeneralitat Valenciana Prometeo/2020/085Spanish MINECO FPI-SO: SEV-2015-0548-17-4, BES-2017-082319ANID Fondecyt Postdoctorado 323055

    IT NECESSARY TO NORMALIZE JUMP TEST RESULTS TO ANTHROPOMETRIC PARAMETERS?

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    The purpose of the present study was to analyse the relationship of different normalization methods in the jump performance, obtained from a digital application (My Jump 2 ®). 189 young women made up the sample. Each of them had to perform three attempts of a bilateral countermovement jump (CMJ) in front of a mobile device. The jump height (JH) and power (P) were the main results, which were processed to normalize them. The JH was normalized to height (JH/H) and to leg length (JH/LL). P was normalized to body mass (RP), while force values were divided by the time of jump to get the Explosive Index of Strength (EIS). The results showed a good association and poor prediction between the variables JH and P, not so between JH and EIS, where no significant relationship was observed. However, a strong relationship was observed between JH / LL and RP (r = 0.801; r2 = 0.641; p KEYWORDS: Smartphone app, vertical jump, biomechanics

    Seasonal streamflow forecast in the Iberian Peninsula based on lagged teleconnection indices

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    Ponencia presentada en: IX Congreso de la Asociación Española de Climatología celebrado en Almería entre el 28 y el 30 de octubre de 2014.[EN]This work assesses the potential of teleconnection indices as predictors of seasonal streamflow in the Iberian Peninsula (IP). The database comprises 382 streamflow time series from gauging stations, covering the period from October 1975 to September 2008. Four forecasting scenarios were developed, considering the information provided by teleconnection indices from one year to the previous season to the seasonal streamflow to be predicted.[ES]En este trabajo se ha evaluado la capacidad predictiva de los índices de teleconexión de estaciones previas sobre el caudal estacional de los ríos en la Península Ibérica. La base de datos de caudal la conforman 382 estaciones de aforo cubriendo el periodo desde octubre de 1975 hasta septiembre de 2008. Adicionalmente, se consideraron cuatro escenarios de predicción, en función de la información climática disponible con cuatro, tres, dos o una estaciones de adelanto.The Spanish Ministry of Science and Innovation, with additional support from the European Community Funds (FEDER), project CGL2010-21188/CLI and the Regional Government of Andalusia, project P11-RNM-7941, which had financed this study
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