2,177 research outputs found

    Unveiling interactions between DNA and cytotoxic 2-arylpiperidinyl-1,4-naphthoquinone derivatives: A combined electrochemical and computational study

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    Indexación: Scopus.Three 2-arylpiperidinyl-1,4-naphthoquinone derivatives were synthesized and evaluated in vitro to determine their cytotoxicity on cancer and normal cell lines. In order to establish their possible action mechanism, the electrochemical behaviour of these quinones was examined using cyclic voltammetry (CV) as technique by using a three-electrode setup: a glassy carbon, Ag/AgCl (in 3 M KCl), and platinum wire as working, reference, and counter electrodes, respectively. Kinetic studies were done to determine the control of the reduction reaction and the number of transferred electrons in the process. Furthermore, the addition of dsDNA to the quinone solutions allowed for the observation of an interaction between each quinone and dsDNA as the current-peaks became lower in presence of dsDNA. Otherwise, motivated to support the aforementioned results, electronic structure calculations at the TPSS-D3/6-31+G(d,p) level of theory were carried out in order to find the most favourable noncovalently bonded complexes between quinones and DNA. Noncovalent complexes formed between DNA and 2-arylpiperidinyl-1,4-naphthoquinones and stabilized by π-stacking interactions along with the well-known hydrogen-bonded complexes were found, with the former being more stable than the latter. These results suggest that the intercalation of these quinone derivatives in DNA is the most likely action mechanism. © 2018 King Saud Universityhttps://www.sciencedirect.com/science/article/pii/S1878535218300893?via%3Dihu

    Enterprise Architecture Approach for Project Management and Project-Based Organizations: A Review

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    Project-based organizations (PBOs) derive income from conducting projects for their clients. Maintaining the most effective and efficient project governance style is an ongoing process for these organizations as the context continuously changes. Enterprise architecture (EA) is a systemic approach that supports organizations in modeling and describing themselves in different layers, such as strategy, business, application, and technology. This literature review describes the current state of EA usage in improving and quickly revising project management governance in PBOs to benefit practitioners and researchers for an integrated view of EA, PM, and PBO, and identification of future research gaps. This review used an EA model composed of layers as an analytical framework. The extracted bibliometric and content data from selected articles were processed using the VOSviewer tool for identifying and understanding the relationships between main concepts through network mapping. The selected articles are oriented to internal organization projects, mainly in information technology (IT). The need to align projects with business is highlighted, with EA positioned as a governance tool. It was found that application of EA in PBOs is rare. A trend toward using popular PM and EA frameworks, such as PMBOK and ArchiMate, was observed

    Estimación de la edad y patrón de crecimiento del abade, Mycteroperca fusca (Serranidae) en una población isleña en la costa noroeste de África

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    Mycteroperca fusca is one of the main predators of the Canarian archipelago coastal marine ecosystem. Nothing is known on the life history or population dynamics of this predatory serranid fish. In this study, age and growth of M. fusca were investigated by annual growth increment counts from 214 fish collected between January 2004 and December 2005. A year’s growth is represented by one opaque and one translucent ring. The island grouper is a slow-growing and long-lived species, with ages up to twenty years recorded. Length at age was described by the von Bertalanffy growth model (L∞=898 mm; k=0.062 year-1; and t0= −3.83 year), the Schnute growth model (y1=262 mm; y2=707 mm; a=0.008; and b=1.98), and the seasonalised von Bertalanffy growth model (L∞=908 mm; k=0.061 year-1; t0= −3.83 year; C=2.58; and ts=0.542). Males and females show differences in growth.Mycteroperca fusca es uno de los principales depredadores de los ecosistemas marinos del Archipiélago Canario, del que nada se conoce sobre su biología. En este trabajo, se aborda el estudio de la edad y el crecimiento de M. fusca mediante el recuento de los incrementos anuales de crecimiento a partir de 214 ejemplares recolectados entre enero de 2004 y diciembre de 2005. El crecimiento anual está representado por un anillo opaco y otro translúcido. El abade es una especie perteneciente a la familia Serranidae de crecimiento lento y de vida larga, con edades registradas superiores a los veinte años. La relación entre la talla y la edad se estimó mediante el modelo de von Bertalanffy (L∞=898 mm; k=0.062 años-1; y t0= −3.83 años), el modelo de Schnute (y1=262 mm; y2=707 mm; a=0.008; y b=1.98), y el modelo estacional de von Bertalanffy (L∞=908 mm; k=0.061 años-1;

    Biología reproductora del abade (Mycteroperca fusca) en las Islas Canarias, costa noroeste de África

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    This is the first time that the reproductive characteristics of Mycteroperca fusca have been analyzed over the whole area of its distribution, using the parameter of the histological analysis of the gonads. This species is a protogynous hermaphrodite with a marked predominance of females (1:4.9). The males and females displayed marked differences in the distribution of the sizes. The females were distributed over all the size ranges analyzed (229-725 mm total length), whereas the males were observed within the larger sizes, as of 428 mm. One transitional specimen (610 mm total length) was observed. The size at which the females first reached sexual maturity was 335 mm total length whereas the size at which 95% of females reached sexual maturity was 398 mm total length. The average size at which 50% of the females had inverted to the male condition was found to be 678 mm total length. The range of sizes at which the process of sexual inversion took place was broad, between 428 and 725 mm total length. The reproductive period was long, almost covering the annual cycle, although the maximum activity was observed between April and October, with a peak in spawning in June-July.Este es el primer estudio que aborda las características reproductoras de Mycteroperca fusca, en toda su área de distribución, utilizando el estudio histológico de las gónadas. La especie se caracteriza por un hermafroditismo proterogínico. Existe una marcada predominancia de las hembras (1:4.9). Los machos y las hembras muestran marcadas diferencias en la estructura de tallas. Las hembras se distribuyen en todo el rango de tallas analizado (229-725 mm de longitud total) mientras que los machos sólo fueron observados en las tallas superiores, por encima de los 428 mm de longitud total. Se analizó un ejemplar intersexual de 610 mm de longitud total. La talla a la cual las hembras alcanzan la madurez sexual es 335 mm de longitud total, mientras que la talla a la cual el 95% de las hembras se consideran maduras es 398 mm de longitud total. La talla media a la cual el 50% de las hembras han invertido a la condición de macho fue 678 mm de longitud total. El rango de tallas en el que el proceso de inversión sexual tiene lugar es amplio, entre 428 y 725 mm de longitud total. El periodo reproductivo es amplio, cubriendo casi el ciclo anual completo, aunque el máximo de actividad se localiza entre los meses de abril y octubre, con un máximo de puesta en junio-julio

    La escuela como formadora de hábitos alimentarios a través de los comedores escolares : un estado del arte

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    La falta de seguridad alimentaria, producto de la actual fase del capitalismo, afecta principalmente a las familias que destinan a la comida la mayor parte de sus ingresos. Como resultado, los niños pertenecientes a esas familias, están más expuestos a padecer obesidad, sobrepeso y a no recibir una alimentación que garantice su derecho a la salud, presente y futura. Si bien es principalmente en la familia donde se desarrollan las pautas alimentarias, el placer, el gusto y el rechazo por distintos alimentos, por distintos factores, muchas familias se ven impelidas en la actualidad a completar la alimentación de sus hijos a través de los comedores escolares. En situaciones de pobreza, la escuela pública contribuye a enfrentar situaciones de vulnerabilidad alimenticia. Los sectores medios y altos, en tanto, depositan cada vez más en las escuelas de doble escolaridad la responsabilidad por el almuerzo de los hijos. En momentos en que la obesidad infantil, sin distingo de países, avanza de modo alarmante, se valora que los comedores escolares y la escuela como institución educativa, pueden contribuir a disminuir el sobrepeso en la edad adulta. De allí que muchos estudios han empezado a poner foco en qué comen y cómo comen los niños en escuela, tema hasta ahora, poco problematizado en nuestro medio. El propósito de esta ponencia es presentar un estado del arte sobre el papel de los comedores escolares y sus efectos sobre las prácticas alimentarias de los niños así como las posibles interacciones entre alimentación escolar y promoción de hábitos alimentarios y de comensalidad con potencialidades para prevenir la obesidad infantil.Fil: Bustos, Rosa María . Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Illobre, Graciela . Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Molina, Cecilia . Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Weisstaub, Sergio G. . Universidad de Chil

    Astrometric Effects of a Stochastic Gravitational Wave Background

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    A stochastic gravitational wave background causes the apparent positions of distant sources to fluctuate, with angular deflections of order the characteristic strain amplitude of the gravitational waves. These fluctuations may be detectable with high precision astrometry, as first suggested by Braginsky et al. in 1990. Several researchers have made order of magnitude estimates of the upper limits obtainable on the gravitational wave spectrum \Omega_gw(f), at frequencies of order f ~ 1 yr^-1, both for the future space-based optical interferometry missions GAIA and SIM, and for VLBI interferometry in radio wavelengths with the SKA. For GAIA, tracking N ~ 10^6 quasars over a time of T ~ 1 yr with an angular accuracy of \Delta \theta ~ 10 \mu as would yield a sensitivity level of \Omega_gw ~ (\Delta \theta)^2/(N T^2 H_0^2) ~ 10^-6, which would be comparable with pulsar timing. In this paper we take a first step toward firming up these estimates by computing in detail the statistical properties of the angular deflections caused by a stochastic background. We compute analytically the two point correlation function of the deflections on the sphere, and the spectrum as a function of frequency and angular scale. The fluctuations are concentrated at low frequencies (for a scale invariant stochastic background), and at large angular scales, starting with the quadrupole. The magnetic-type and electric-type pieces of the fluctuations have equal amounts of power.Comment: 23 pages, 2 figures, references added and minor text correction

    Interview Douglas D. Perkins: “Social Work has learnings that allows to achieve more power and impact through working effectively with groups of people”

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    Douglas Perkins is recognized worldwide for his work in Community Psychology, social capital development, citizen participation, empowerment and sense of community. He is currently the founding director of the PhD “Research and Community Action” in the Department of Human Development and Organization and Community Studies Center at the Vander at the Vanderbilt University. He also serves as associate editor of the journal Psychosocial Intervention. He has linked research and teaching with participation in various community organization projects, migration networks, public education and health, among others. His academic work also includes topics on ecological change, evaluation of programs and development of research methods with communities. He has also developed interdisciplinary studies about the relationship between social psychology, law and public policy. The following interview was made during her visit to Chile in October 2018

    Thirty Meter Telescope Site Testing I: Overview

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    As part of the conceptual and preliminary design processes of the Thirty Meter Telescope (TMT), the TMT site testing team has spent the last five years measuring the atmospheric properties of five candidate mountains in North and South America with an unprecedented array of instrumentation. The site testing period was preceded by several years of analyses selecting the five candidates, Cerros Tolar, Armazones and Tolonchar in northern Chile; San Pedro Martir in Baja California, Mexico and the 13 North (13N) site on Mauna Kea, Hawaii. Site testing was concluded by the selection of two remaining sites for further consideration, Armazones and Mauna Kea 13N. It showed that all five candidates are excellent sites for an extremely large astronomical observatory and that none of the sites stands out as the obvious and only logical choice based on its combined properties. This is the first article in a series discussing the TMT site testing project.Comment: Accepted for publication in PASP, April 2009 issu

    Simulating residential electricity and heat demand in urban areas using an agent-based modelling approach

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    Cities account for around 75% of the global energy demand and are responsible for 60-70% of the global greenhouse gasses emissions. To reduce this environmental impact it is important to design efficient energy infrastructures able to deal with high level of renewable energy resources. A crucial element in this design is the quantitative understanding of the dynamics behind energy demands such as transport, electricity and heat. In this paper an agent-based simulation model is developed to generate residential energy demand profiles in urban areas, influenced by factors such as land use, energy infrastructure and user behaviour. Within this framework, impact assessment of low carbon technologies such as plug-in electric vehicles and heat pumps is performed using London as a case study. The results show that the model can generate important insights as a decision support tool for the design and planning of sustainable urban energy systems

    Socially aware robot navigation system in human-populated and interactive environments based on an adaptive spatial density function and space affordances

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    Traditionally robots are mostly known by society due to the wide use of manipulators, which are generally placed in controlled environments such as factories. However, with the advances in the area of mobile robotics, they are increasingly inserted into social contexts, i.e., in the presence of people. The adoption of socially acceptable behaviours demands a trade-off between social comfort and other metrics of efficiency. For navigation tasks, for example, humans must be differentiated from other ordinary objects in the scene. In this work, we propose a novel human-aware navigation strategy built upon the use of an adaptive spatial density function that efficiently cluster groups of people according to their spatial arrangement. Space affordances are also used for defining potential activity spaces considering the objects in the scene. The proposed function defines regions where navigation is either discouraged or forbidden. To implement a socially acceptable navigation, the navigation architecture combines a probabilistic roadmap and rapidly-exploring random tree path planners, and an adaptation of the elastic band algorithm. Trials in real and simulated environments carried out demonstrate that the use of the clustering algorithm and social rules in the navigation architecture do not hinder the navigation performance
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