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

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

Evaluación de tres cultivares de tomate (Solanum Lycopersicum L.) y tres dosis de fertilización, bajo riego por micro aspersión en época seca, UNA, Managua, 2016

El tomate es una de las hortalizas más importante en Nicaragua, tanto en consumo como en comercialización, en el país el cultivo inicio en el año 1940, y actualmente los rendimientos varían en un rango de 12 y 18 toneladas ha-1, Estos rendimientos pueden verse afectados por plagas y enfermedades que perjudican el cultivo, incrementando los costos de producción por el uso frecuente de productos químicos para su control. El objetivo de esta investigación fue evaluar el efecto de tres cultivares de tomate (F1 IT 105, F1 Savana Y F1 Kiara), con respecto a tres dosis de fertilización, en proporciones completo de 12 – 30 – 10 (113 kg ha-1, 90 kg ha-1 Y 67 kg ha-1). El ensayo se estableció en el área experimental de la Facultad de Agronomía, adscrito a la Universidad Nacional Agraria, ubicada en el kilómetro 12 ½ carretera norte. Este se encuentra ubicado a 12° 08’ 36’’ latitud Norte y 86° 9’ 49’’ longitud Oeste a una altura de 56 msnm. El suelo presenta un pH de 8.03, con pendiente entre 0 y 2 %. Se utilizó un diseño de arreglo en franjas con 5 repeticiones, los datos fueron analizados mediante el Análisis de Varianza (ANDEVA) y separación de medias por Tukey (α<0.05). Las variables altura de planta, diámetro del tallo, número de ramas, número de frutos por planta, racimo por planta, cantidad de semillas por fruto, diámetro del lóculo, y la segunda toma de datos del fruto mostraron efectos significativos en los factores estudiados. Las variables pericarpio del tomate, primera y cuarta cosecha de la variable fruto no mostraron algún efecto estadístico. De igual manera, la tercera y cuarta cosecha para el factor dosis de fertilización edáfica aplicada no se vio afectada estadísticamente. Los rendimientos resultaron significativos con los promedios más altos para la cultivar F1 Savana con 7,223.6 kg ha-1, y con 8,096 kg ha-1 para la dosis más alta de fertilización a 113 kg ha-1

Evaluación de la eficacia y seguridad del plasma rico en factores de crecimiento en el tratamiento de las heridas cutáneas

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Clinical presentation of burning mouth syndrome in patients with oral lichenoid disease

To analyze the presence of burning mouth syndrome (BMS) in a group of patients diagnosed with oral lichenoid disease (OLD). A retrospective study of 217 patients diagnosed with OLD; 158 (72,8%) women and 59 (27,2%) men, with an average age upon diagnosis of 56,4 years (SD 11,88). We carried out a detailed and complete characterization of symptoms, with special emphasis on BMS diagnostic data specified by the International Headache Society. Four patients (1.8%) presented with long-term clinical symptoms of burning mouth, indicative of BMS and they fulfilled the IHS 2018 criteria, except for criterion D, i.e.?Oral mucosa is of normal appearance?. The observed lichenoid mucosal lesions were not considered to be able to account for the reported intraoral pain in any of our patients. Thus neither diagnosis was considered to be exclusive. Patients diagnosed with OLD, and who simultaneously present clinical characteristics of BMS should be studied in detail, in order to evaluate the possibility of both diagnoses concurring

Selective Harmonic Mitigation Technique for High-Power Converters

In high-power applications, the maximum switching frequency is limited due to thermal losses. This leads to highly distorted output waveforms. In such applications, it is necessary to filter the output waveforms using bulky passive filtering systems. The recently presented selective harmonic mitigation pulsewidth modulation (SHMPWM) technique produces output waveforms where the harmonic distortion is limited, fulfilling specific grid codes when the number of switching angles is high enough. The related technique has been previously presented using a switching frequency that is equal to 750 Hz. In this paper, a special implementation of the SHMPWM technique optimized for very low switching frequency is studied. Experimental results obtained applying SHMPWM to a three-level neutral-point-clamped converter using a switching frequency that is equal to 350 Hz are presented. The obtained results show that the SHMPWM technique improves the results of previous selective harmonic elimination pulsewidth modulation techniques for very low switching frequencies. This fact highlights that the SHMPWM technique is very useful in high-power applications, leading its use to an important reduction of the bulky and expensive filtering elements.Ministerio de Ciencia y Tecnología TEC2006-03863Junta de Andalucía EXC/2005/TIC-117

Memoria de restauración de la torre de Vallferosa (La Segarra, Lleida)

En este artículo se analizan los trabajos de restauración llevados a cabo en la torre de Vallferosa (La Segarra, Lleida) entre los años 2006 y 2009, siguiendo el proyecto redactado por los autores. Se expone en primer lugar el proceso de revalorización de este monumento en la historiografía reciente, en segundo lugar su marco legal, en tercer lugar los datos históricos básicos que se disponen de él, en cuarto lugar su descripción con anterioridad a la restauración, en quinto lugar las patologías que sufría en 2006, en sexto lugar los criterios seguidos en la intervención, y finalmente, en séptimo lugar, una relación sucinta de los trabajos llevados a cabo

Production of gas diffusion layers with cotton fibers for their use in fuel cells

The gas diffusion layer (GDL) is one of the most important parts of a proton exchange membrane fuel cell, that plays a key role transporting the current to the collector plates, distributing the reactant gases to the catalyst surface, and evacuating heat and water that is generated during the redox reactions inside the fuel cell. Speaking in terms of production cost, the GDL represents up to 45% of the total cost of the membrane electrode assembling (MEA). However, and despite its crucial role in a fuel cell, until recent years, the GDLs have not been studied with the same intensity as other MEA components, such as the catalyst or the proton exchange membrane. In this work, we present the production process, at laboratory scale, of a low cost GDL, using a non-woven paper-making process. A relevant aspect of this GDL is that up to 40% of their composition is natural cotton, despite which they present good electrical and thermal conductivity, high porosity, good pore morphology, high hydrophobicity as well as gas permeability. Furthermore, when the GDL with its optimum cotton content was tested in a single open cathode fuel cell, a good performance was obtained, which makes this GDL a promising candidate for its use in fuel cells.The authors acknowledge the foresight to the Universidad Politécnica de Cartagena for providing a new laboratory for hydrogen research. AJN thanks the Universidad Politécnica de Cartagena for awarding a grant of Iniciación a la Investigación financed by the Santander Bank. AJN and MAG are actually working on this project with a contract funded by the Comunidad Autónoma de la Región de Murcia, Consejeria de Desarrollo Económico, Turismo y Empleo, and the European Union, through the program RIS3MUR with Ref: 2I20SAE00079. Authors wish to thank to Prof. Dr. José Antonio Mompean González of the Department of English of the University of Murcia, for the revision of this manuscript

Effect of silvicultural treatments on forest diversity and structure in temperate forests under management in Durango, Mexico

The present study evaluated the effect of silvicultural treatments on the diversity and structure of species in temperate forest ecosystems in the Municipality of Pueblo Nuevo in the State of Durango, Mexico; it was carried out to know if forest use modifies the diversity, mixture of species, spatial distribution, and dimensional differentiation of individuals in these ecosystems. The evaluation was carried out by comparing 10 plots with management history, which were measured before the application of the treatment and five years later. The diversity indices of Shannon, Simpson and Margalef were compared, as well as indices of structure of mixture of species, spatial distribution, and dimensional differentiation. According to the silvicultural treatments applied, the values of the indices do not present significant differences in their evaluations (p&gt; 0.05), which indicates that forest use does not modify the diversity and structure of species of the tree stratum of this plant community

The Influence of Urban Environments on Oxidative Stress Balance: A Case Study on the House Sparrow in the Iberian Peninsula

The House Sparrow is a globally distributed species and is closely associated with anthropised environments. They are well-adapted to urban life; therefore the decline of their populations in Europe represents an unexpected event that demands an investigation into its causes. Causes that have promoted this decline are not well-known, but one of the highlighted hypotheses is an increase of oxidative stress linked to the toxicity of pollution in urban areas. From an ecophysiological perspective, oxidative damage, antioxidant defense, and oxidative balance are considered reliable indicators of environmental stressors such as pollutants. To carry out this study, blood samples were collected from House Sparrows in three different habitats that varied in terms of urbanization degree: urban, suburban, and rural; during the winter and breeding season. According to our results, urban sparrows showed higher levels of oxidative damage and higher activity of antioxidant enzymes, but lower antioxidant capacity in comparison with the rural birds; and these differences especially increase during the breeding season. The maintenance of oxidative balance increases in an urban environment in comparison to a rural one; we suggest that the high level of pollution and the poor quality diet linked to urban environments. The breeding season is expected to be particularly challenging for the oxidative balance of urban birds, when the reallocation of resources between self-maintenance and reproduction may be critical due to the scarcity of antioxidants found in urban areas. This study may contribute to determining the causes of the population decrease of House Sparrows in cities