Adsorption of Metal Clusters on Graphene and Their Effect on the Electrical Conductivity

When adsorbates are introduced in graphene, the electric conductivity is highly modified. This chapter discusses how to estimate the electrical conductivity of graphene sheets with adsorbates, using electronic structure calculations and some theoretical approaches. Also, we discussed how the clustering of adsorbates attached to the graphene can impact electrical conductivity. We will focus in using metallic clusters as adsorbates (Mn; M = Ag, Au, Pt, and Pd; n = 1, 2, 3, and 4). The electrical conductivity is found using theoretical approaches, which are summarized in this chapter. We compare these approaches between each other to determine which is the most appropriate for each system

El impacto de las políticas de apoyo a las Micro, Pequeñas y Medianas Empresas en México.

En los últimos veinte años se ha dado un amplio debate en la teoría y política económica sobre la necesidad de la intervención gubernamental, a través de una política industrial que fomente el desarrollo económico. En México, el diseño de las políticas de apoyo para Micro, Pequeñas y Medianas Empresas (MiPyME) ha estado sujeto a la consideración de cuestiones acerca de la relevancia del tamaño como variable de restricción de las capacidades y oportunidades de estas empresas en el mercado. El objetivo principal de esta investigación es evaluar el impacto en el desarrollo de las políticas destinadas al fomento de la competitividad MiPyME en el estado de Quintana Roo, México

El impacto de las políticas de apoyo a las Micro, Pequeñas y Medianas Empresas en México.

En los últimos veinte años se ha dado un amplio debate en la teoría y política económica sobre la necesidad de la intervención gubernamental, a través de una política industrial que fomente el desarrollo económico. En México, el diseño de las políticas de apoyo para Micro, Pequeñas y Medianas Empresas (MiPyME) ha estado sujeto a la consideración de cuestiones acerca de la relevancia del tamaño como variable de restricción de las capacidades y oportunidades de estas empresas en el mercado. El objetivo principal de esta investigación es evaluar el impacto en el desarrollo de las políticas destinadas al fomento de la competitividad MiPyME en el estado de Quintana Roo, México. In the last twenty years there has been much debate in economic theory and policy on the need for government intervention through industrial policy to promote economic development. In Mexico, the development of policy for Micro, Small and Medium Enterprises (MSME) has been subject to the consideration of questions about the relevance of variable size and restrictions on the capabilities and opportunities of these firms in the market. The aim of this research is to analyze and evaluate the impact on the development of policies for the promotion of MSME competitiveness in Quintana Roo state, Mexico.MiPyME, gobierno, política industrial, programas, sector público. MSME, government, industrial policy, programs, public sector.

Lectores y escritores: la creación literaria a través de Wattpad en la era de la cultura participativa

En el presente trabajo se expone un caso de lectura y escritura participativas realizadas en el contexto de una comunidad de aprendizaje mutuo en soporte virtual llamada Wattpad. Se enfatiza el concepto de cultura participativa que cobra especial importancia en estos nuevos escenarios de creación literaria. Por medio de un método de etnografía participativa se analizó el caso de una escritora considerada una micro celebridad, y una de sus obras con mayor impacto entre los lectores. Se les dio seguimiento a sus publicaciones durante seis meses, así como a las interacciones generadas entre los lectores a través de las aportaciones o comentarios vertidos en los capítulos. Se utilizaron las técnicas de análisis de contenidos, observación y entrevistas a los seguidores y a la autora, para conocer de qué manera la interacción actúa para transformar la creación literaria convirtiéndola en un producto de cultura participativa. Se concluye que, en efecto, estas nuevas formas de interactuar en plataformas virtuales permiten remodelar las creaciones literarias que finalmente se comparten como un producto que gratifica a una comunidad

Periodontitis and alzheimer´s disease

Alzheimer's disease (AD), the main cause of dementia in the adult population, is characterized by a progressive loss of cognitive function. It is considered that neuroinflammation plays a fundamental role in its onset and progression. The bacteria present in the disbiotic microbiome generated during the course of periodontitis (PE) are capable of inducing a systemic inflammatory response, exacerbating the production of proinflammatory mediators that have the potential to spread to the systemic circulation. Several hypotheses point to similar pathophysiological pathways in the establishment of AD and PE, sharing cellular and molecular proinflammatory characteristics. In periodontitis, locally produced cytokines and pro-inflammatory products spread from the ulcerated periodontal pocket into the systemic circulation, or around the trigeminal nerve terminals, which allows the passage of bacteria or their products to the brain. This fact leads to the formation of plaques of amyloid peptide and intraneuronal neurofibrillar tangles (NFTs) that activate the glial cells producing a significant increase in proinflammatory cytokines in the affected regions that lead to a loss of neuronal synapses and neurodegeneration, contributing to the progression of AD. This review of the literature contributes to the understanding of the pathological pathways shared by both diseases such as oxidative damage and inflammation. There is not enough evidence to determine an association between this two pathologies, so it is considered necessary to conduct studies for determine if periodontitis is capable of inducing or exacerbating the neuroinflammation that will trigger AD

Spatial distribution of nitrate health risk associated with groundwater use as drinking water in Merida, Mexico

Water containing nitrate levels above 45 mg/l is not recommended for human consumption and its prolonged intake is associated with various health conditions. In Merida city, Mexico, the only source for water supply is a karstic aquifer, but the absence of sewerage and drainage networks makes it highly vulnerable to anthropogenic contamination. In this work, the concentration and spatial distribution of nitrate in the Merida's karstic aquifer were assessed by statistical and geostatistical techniques. The sources of nitrate contamination were tracked by making statistical correlations between nitrate concentrations and key ions; the potential risk to human health was also estimated by using the Hazard Index (HI). A total of 177 groundwater samples were collected from the four water supply systems serving Merida, during 2012 and 2013. Nitrate concentrations from collected samples varied between 15.51 and 70.61 mg/l, with maximum and minimum concentrations per sampling point ranging from 47.47 to 70.61 mg/l and from 15.51 to 17.32 mg/l, respectively. Significant positive correlations (P < 0.05) between nitrates and chlorides, sulphates and potassium were found, which may indicate potential contamination from domestic wastewater and agricultural activities. The spatial distribution of nitrate concentrations in the aquifer revealed an increase in nitrates following a trajectory SoutheNorth West, towards central and northwestern zones within Merida Metropolitan Area. From the health risk analysis, it was found that infants exposed at current nitrate levels are at a higher risk (HIMAX ¼ 1.40) than adults (HR < 1.0) and therefore, there is a clear need for implementing effective strategies to protect groundwater quality and to better manage and control nitrate pollution sources

A pequena empresa sob um contexto de crise financeira: uma análise da sua sobrevivência

This research aims to characterize small businesses that survived (crisis 2008) in the City of Buffalo, New York, United States of America. According to the literature on the subject, the main authors cited are Chrisman et al (1999), Dahlqvist et al (2000), Fotopoulous and Louri (2000), Fritsch et al. (2006), Hannan and Freeman (1977) Littunen et al (1998), Lussier and Pfeifer (2001), Lussier (1996), Reid (1999), Van Praag (2003). The methodology used is of an explanatory type and the clustering technique (cluster) was used as an analysis tool, which allowed to determine the characteristics of the companies that survived. For information collection, a structured questionnaire was applied to 56 small enterprises established in the city of Buffalo, New York, during the period from July 2014 to November 2015. The results show that there are two groups of small surviving companies: A) the first one is made up of businesses that are characterized by a management model and an information system that allow the generation of reports (Financial Statements, Inventories, Customer Analysis, among others) for decision making and b) the second, it integrates commercial establishments that have a business strategy based on their comparative advantages and innovation in their management systems.La presente investigación tiene como objetivo caracterizar a las pequeñas empresas que sobrevivieron a la crisis de 2008 en la Ciudad de Buffalo, Nueva York, Estados Unidos de América. De acuerdo a la literatura especializada en el tema, los principales autores citados son Chrismanet al(1999),Dahlqvist et al (2000), Fotopoulous y Louri (2000),Fritsch et al(2006),Hannan y Freeman (1977), Littunenet al(1998),Lussier y Pfeifer(2001),Lussier (1996), Van Praag (2003). La metodología utilizada es de tipo explicativo y se utilizócomo herramienta de análisis la técnica de conglomerados (clúster), la cual permitió determinar las características de las empresas que sobrevivieron. Para la recolección de información, se aplicó un cuestionario estructurado a 56 pequeñas empresas establecidas en el la ciudad de Buffalo, Nueva York, durante el período comprendido de Julio de 2014 a Noviembre de 2015.Los resultados evidencian que existen dos grupos de pequeñas empresas sobrevivientes: a) el primero se encuentra conformado por negocios que se caracterizan por un modelo de gestión y un sistema de información que permiten la generación de reportes (Estados Financieros, Inventarios, Análisis de Clientes, entre otros) para la toma de decisiones y b) el segundo integra a los establecimientos comerciales que cuentan con una estrategia de negocios basada en sus ventajas comparativas e innovación en sus sistemas de gestión.A presente investigação tem como objectivo caracterizar as pequenas empresas que sobreviveram à crise de 2008, na cidade de Buffalo - Nova York, Estados Unidos de América. A revisão da literatura abrange os estudos feitos por Chrisman et al. (1999), Dahlqvist et al. (2000), Fotopoulous e Louri (2000), Fritsch et al. (2006), Hannan e Freeman (1977), Littunen et al. (1998), Lussier e Pfeifer (2001), Lussier (1996), Van Praag (2003), considerados como fundamentais aos argumentos apresentados e pelas contribuições a nível da ciência, relativamente ao tema em questão. A metodologia utilizada é de tipo explicativo e utilizou-se, como ferramenta de análise, a técnica de conglomerados (clúster), a qual permitiu determinar as características das empresas que sobreviveram à referida crise. Para a recolha de informação, aplicou-se um questionário estruturado a 56 pequenas empresas existentes na cidade de Buffalo-Nova York, durante o período compreendido entre Julho de 2014 a Novembro de 2015. Os resultados evidenciam que existem dois grupos de pequenas empresas sobreviventes, nomeadamente: O primeiro é caracterizado por negócios apresentados, por meio de um modelo de gestão e um sistema de informação que permitem apresentar relatórios (Estados Financeiros, Inventários, Análise de Clientes, entre outros), com vista à tomada de decisões. O segundo integra os estabelecimentos comerciais que contam com uma estratégia de negócios, baseada nas suas vantagens comparativas e inovação dos seus sistemas de gestão