4,596 research outputs found
Solving multi-objective hub location problems by hybrid algorithms
In many logistic, telecommunications and computer networks, direct routing of
commodities between any origin and destination is not viable due to economic and technolog-
ical constraints. In that cases, a network with centralized units, known as hub facilities, and a
small number of links is commonly used to connect any origin-destination pair. The purpose
of these hub facilities is to consolidate, sort and transship e ciently any commodity in the
network. Hub location problems (HLPs) consider the design of these networks by locating a
set of hub facilities, establishing an interhub subnet, and routing the commodities through
the network while optimizing some objective(s) based on the cost or service.
Hub location has evolved into a rich research area, where a huge number of papers have
been published since the seminal work of O'Kelly [1]. Early works were focused on analogue
facility location problems, considering some assumptions to simplify network design. Recent
works [2] have studied more complex models that relax some of these assumptions and in-
corporate additional real-life features. In most HLPs considered in the literature, the input
parameters are assumed to be known and deterministic. However, in practice, this assumption
is unrealistic since there is a high uncertainty on relevant parameters, such as costs, demands
or even distances.
In this work, we will study the multi-objective hub location problems with uncertainty.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
Distribution of sea-air CO 2 fluxes in the Patagonian Sea: Seasonal, biological and thermal effects
Sea-air CO2 fluxes (FCO2) in the Patagonian Sea (PS) were studied using observations collected in 2000-2006. Based on the PS frontal structures and the thermal and biological contributions to FCO2 we present a regional subdivision between distinct regimes that provide new insights on the processes that control these fluxes. The coastal regime (CR) is a net source of atmospheric CO2 (4.9 x 10-3mol.m-2.d-1) while the open shelf regime (SHR) is a net CO2 sink (-6.0 x 10-3mol.m-2.d-1). The interface between these two regions closely follows the location of along-shore fronts. In addition, based on the nature of the processes that drive the FCO2, the PS is subdivided between northern (NR) and southern (SR) regions. Both, NR and SR are CO2 sinks, but the CO2 uptake is significantly higher in NR (-6.4 x 10-3mol.m-2.d-1) than in SR (-0.5 x 10-3mol.m-2.d-1). The data reveal a strong seasonality in FCO2. The mean CO2 capture throughout the PS in austral spring is -5.8 x 10-3mol.m-2.d-1, reaching values lower than -50 x 10-3mol.m-2.d-1 in NR, while in winter FCO2 is close to equilibrium in SR. The analysis of the biological and thermal effects (BE and TE, respectively) on seasonal pCO2 variability indicates that regions of CO2 emission are dominated by the TE while regions of CO2 uptake are dominated by the BE. Our results indicate that the biological pump is the dominant process determining the sea-air CO2 flux in the PS.Fil: Kahl, Lucía Carolina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; ArgentinaFil: Bianchi, Alejandro A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; ArgentinaFil: Osiroff, Ana Paula. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; ArgentinaFil: Pino, Diana Ruiz. Universite Pierre et Marie Curie; FranciaFil: Piola, Alberto Ricardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Materiales calcolíticos procedentes de "La Longuera" (El Viso, Córdoba)
El norte de la provincia de Córdoba conforma un marco de enorme interés para el análisis de los primeros momentos de la metalurgia en Andalucía Occidental dada la excepcional riqueza en recursos mineros, y muy especialmente cupríferos que encierra su subsuelo. A este hecho viene a sumarse su singularidad geográfica como lugar de interrelación entre los desarrollos culturales coetáneos en el valle del Guadalquivir, Extremadura y zona occidental de la Submeseta sur. Conscientes de estos hechos, nos planteamos hace varios años un programa de investigación que, partiendo de una serie de prospecciones sistemáticas, nos permitiera una primera y sólida aproximación a la dinámica del Calcolítico en estas tierras cordobesas, labor que ya ha dado sus primeros frutos (MURILLO, 1986,1986 b, 1987) y en la que debe inscribirse el presente trabajo
Estima de la composición corporal en conejos de 25 a 77 días de edad mediante la técnica de impedancia bioeléctrica (BIA).
El objetivo de este trabajo fue determinar y validar con datos independientes las ecuaciones de predicción obtenidas para estimar in vivo la composición corporal de conejos en crecimiento utilizando la técnica de impedancia bioeléctrica (BIA). Las ecuaciones se calcularon mediante un análisis de regresión múltiple a partir de las medidas de impedancia presentadas en el trabajo anterior (Saiz et al., 2011) y de otras variables independientes que fueron incluidas en el modelo, tras hacer un análisis de selección de variables, como la edad, el peso y la longitud del animal. Los coeficientes de determinación (R2) de las ecuaciones para estimar la humedad (g), la proteína (g), la grasa (g), las cenizas (g) y la energía (MJ) fueron: 0,99, 0,99, 0,97, 0,98 y 0,99, y los errores medios de predicción relativos (EMPR): 2,24, 5,99, 16,3, 8,56 y 7,81%, respectivamente. El R2 y EMPR para estimar el porcentaje de humedad corporal fueron de 0,85 y 1,98%, respectivamente. Para predecir los contenidos, expresados sobre materia seca (MS), de proteína (%), grasa (%), cenizas (%) y energía (kJ/100g), el R2 obtenido fue 0,79, 0,83, 0,71 y 0,86, respectivamente y el EMPR 4,78, 12,2, 8,39 y 3,26%, respectivamente. La reactancia estuvo negativamente correlacionada con el contenido en humedad, cenizas y proteína bruta (r=-0,32, Pmenor que0,0001; r=-0,20, Pmenor que0,05; r=-0,26, Pmenor que0,01) pero positivamente con el de grasa y energía (r=0,23 y r=0,24; Pmenor que0,01). Al contrario ocurrió con la resistencia, que estuvo positivamente correlacionada con el contenido en humedad, cenizas y proteína bruta (r=0,31, Pmenor que0,001; r=0,28, Pmenor que0,001; r=0,37, Pmenor que0,0001) pero negativamente con el de grasa y energía (r=-0,36 y r=-0,35; Pmenor que0,0001). Así mismo, la edad del animal, estuvo negativamente correlacionada con el contenido en humedad, proteína y cenizas (r=-0,79, r=-0,67 y r=-0,80; Pmenor que0,0001) y positivamente con la grasa y energía (r=0,78 y r=0,81; Pmenor que0,0001). Se puede considerar la técnica BIA como una técnica útil para estimar in vivo la composición corporal de los conejos en crecimiento de 25 a 77 días de edad
Enhancing the Psychology Curriculum Through Service Learning
Educators in psychology should aspire to encourage students’ holistic growth in academic, personal, and civic domains. We propose that service learning is the most potent pedagogy for developing well-rounded, psychologically literate citizens capable of meeting the goals for the undergraduate psychology major. This article defines service learning, delineates the rationales for service learning, and summarizes research demonstrating the efficacy of this pedagogical approach. The article also describes the learning objectives derived from the American Psychological Association Guidelines for the Undergraduate Major (Version 2.0, 2013), with an emphasis on the ways in which service learning contributes to academic learning, civic learning, and personal growth. Finally, the article illustrates the four types of service learning, and it provides a concrete example for structuring reflection in order to connect community experiences with course content in a service learning psychology course
FtsZ of filamentous, heterocyst-forming cyanobacteria has a conserved N-Terminal peptide required for normal FtsZ polymerization and cell division
Filamentous cyanobacteria grow by intercalary cell division, which should involve distinct steps compared to those producing separate daughter cells. The N-terminal region of FtsZ is highly conserved in the clade of filamentous cyanobacteria capable of cell differentiation. A derivative of the model strain Anabaena sp. PCC 7120 expressing only an FtsZ lacking the amino acids 2-51 of the N-terminal peptide (1N-FtsZ) could not be segregated. Strain CSL110 expresses both 1N-FtsZ, from the endogenous ftsZ gene promoter, and the native FtsZ from a synthetic regulated promoter. Under conditions of 1N-FtsZ predominance, cells of strain CSL110 progressively enlarge, reflecting reduced cell division, and show instances of asymmetric cell division and aberrant Z-structures notably differing from the Z-ring formed by FtsZ in the wild type. In bacterial 2-hybrid assays FtsZ interacted with 1N-FtsZ. However, 1N-FtsZ-GFP appeared impaired for incorporation into Z-rings when expressed together with FtsZ. FtsZ, but not 1N-FtsZ, interacted with the essential protein SepF. Both FtsZ and 1N-FtsZ polymerize in vitro exhibiting comparable GTPase activities. However, filaments of FtsZ show a distinct curling forming toroids, whereas 1N-FtsZ form thick bundles of straight filaments. Thus, the N-terminal FtsZ sequence appears to contribute to a distinct FtsZ polymerization mode that is essential for cell division and division plane location in Anabaena.Agencia Estatal de Investigación BFU2013-44686-P BFU2016-77097-
Distribución y ecología de Ophionotus victoriae Bell, 1902 (Ophiuroidea, Echinodermata) en el área de las islas Shetland del Sur (Antártida)
We present a distribution analysis for Ophionotus victoriae Bell, 1902, based on abundance data obtained during the Bentart 95 Expedition, on a macrozoobenthos sampling transect from north of Livingston Island to the Antarctic Peninsula, with 24 Agassiz trawls carried out at depths of 40- 850 m. This ophiuroid seems characteristic of the macrobenthic assemblages south of Livingston Island and Deception, where the species represents 60-90% of numerical abundance and 40-80% of biomass for the total epifauna. Pearson and Spearman coefficients correlation showed interesting results which could explain the success of O. victoriae in this area. The highest O. victoriae abundances were related to acidic and carbonated sediments, as well as to mysid density; moreover, the presence of the largest specimens was apparently related to euphasids, and we also found a negative relationship with a filter- feeder biomass.Durante la Campaña Bentart 95 se muestreó el macrozoobentos en 24 estaciones con draga de arrastre Agassiz y a profundidades comprendidas entre 40 y 850 m, sobre un recorrido que cubrió desde el norte de la isla Livingston hasta la península Antártica. A partir de los datos de abundancia obtenidos se analiza la distribución de Ophionotus victoriae Bell, 1902. Esta ofiura parece caracterizar las comunidades macrobentónicas en las zonas al sur de Livingston y en la isla Decepción, donde constituye entre el 60 y el 90%, y del 40 al 80 % de la abundancia numérica y la biomasa, respectivamente, del total de la epifauna. La aplicación de las correlaciones de Pearson y Spearman arroja resultados interesantes que podrían explicar el éxito de O. victoriae en esta región. Las mayores abundancias de O. victoriae se relacionarían con los sedimentos acidificados y con la mayor concentración de carbonatos, así como con la densidad de misidáceos; mientras, se observa una relación negativa con la biomasa de filtradores, y la presencia de ejemplares de mayor tamaño parece relacionada directamente con la presencia de eufasiáceos.Instituto Español de Oceanografí
Análisis del rendimiento en salto vertical, agilidad,
Objetivo
Analizar la influencia de la categoría de edad en la capacidad de salto, sprint, agilidad y velocidad de golpeo en futbolistas jóvenes.
Método
Estudio transversal en el que participaron 36 jugadores de nivel subélite provenientes de las categorías inferiores (cadete y juvenil) de equipos de fútbol andaluces (edad: 15,87 ± 1,43 años; masa corporal: 65,38 ± 10,84 kg; altura: 1,71 ± 0,06 m). Se evaluó la composición corporal, el rendimiento en salto vertical (CMJ), la agilidad mediante el test de Balsom, velocidad de sprint en 5, 10, 20 y 30 m y la velocidad de golpeo con ambas piernas.
Resultados
Los análisis mostraron que los jugadores juveniles tienen mayor rendimiento en los test de CMJ, agilidad y velocidad de golpeo con ambas piernas que los cadetes. No se aprecian diferencias significativas (p ≥ 0,05) en la prueba de velocidad, aunque se evidencia una clara tendencia a favor de los juveniles.
Conclusión
Existe efecto de la edad durante la etapa de la adolescencia sobre la capacidad de salto, la agilidad, la velocidad de golpeo y, en menor medida, sobre la velocidad de jóvenes jugadores de fútbol, además de asociación entre las capacidades condicionales más influyentes en el rendimiento del futbolista
Effects of increasing the affinity of CarD for RNA polymerase on Mycobacterium tuberculosis growth, rRNA transcription, and virulence
CarD is an essential RNA polymerase (RNAP) interacting protein in Mycobacterium tuberculosis that stimulates formation of RNAP-promoter open complexes. CarD plays a complex role in M. tuberculosis growth and virulence that is not fully understood. Therefore, to gain further insight into the role of CarD in M. tuberculosis growth and virulence, we determined the effect of increasing the affinity of CarD for RNAP. Using site-directed mutagenesis guided by crystal structures of CarD bound to RNAP, we identified amino acid substitutions that increase the affinity of CarD for RNAP. Using these substitutions, we show that increasing the affinity of CarD for RNAP increases the stability of the CarD protein in M. tuberculosis. In addition, we show that increasing the affinity of CarD for RNAP increases the growth rate in M. tuberculosis without affecting 16S rRNA levels. We further show that increasing the affinity of CarD for RNAP reduces M. tuberculosis virulence in a mouse model of infection despite the improved growth rate in vitro. Our findings suggest that the CarD-RNAP interaction protects CarD from proteolytic degradation in M. tuberculosis, establish that growth rate and rRNA levels can be uncoupled in M. tuberculosis and demonstrate that the strength of the CarD-RNAP interaction has been finely tuned to optimize virulence. IMPORTANCE Mycobacterium tuberculosis, the causative agent of tuberculosis, remains a major global health problem. In order to develop new strategies to battle this pathogen, we must gain a better understanding of the molecular processes involved in its survival and pathogenesis. We have previously identified CarD as an essential transcriptional regulator in mycobacteria. In this study, we detail the effects of increasing the affinity of CarD for RNAP on transcriptional regulation, CarD protein stability, and virulence. These studies expand our understanding of the global transcription regulator CarD, provide insight into how CarD activity is regulated, and broaden our understanding of prokaryotic transcription
CarD stabilizes mycobacterial open complexes via a two-tiered kinetic mechanism
CarD is an essential and global transcriptional regulator in mycobacteria. While its biological role is unclear, CarD functions by interacting directly with RNA polymerase (RNAP) holoenzyme promoter complexes. Here, using a fluorescent reporter of open complex, we quantitate RP(o) formation in real time and show that Mycobacterium tuberculosis CarD has a dramatic effect on the energetics of RNAP bound complexes on the M. tuberculosis rrnAP3 ribosomal RNA promoter. The data reveal that Mycobacterium bovis RNAP exhibits an unstable RP(o) that is stabilized by CarD and suggest that CarD uses a two-tiered, concentration-dependent mechanism by associating with open and closed complexes with different affinities. Specifically, the kinetics of open-complex formation can be explained by a model where, at saturating concentrations of CarD, the rate of bubble collapse is slowed and the rate of opening is accelerated. The kinetics and open-complex stabilities of CarD mutants further clarify the roles played by the key residues W85, K90 and R25 previously shown to affect CarD-dependent gene regulation in vivo. In contrast to M. bovis RNAP, Escherichia coli RNAP efficiently forms RP(o) on rrnAP3, suggesting an important difference between the polymerases themselves and highlighting how transcriptional machinery can vary across bacterial genera
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