A statistical comparison of the AMIE derived and DMSP‐SSIES observed high‐latitude ionospheric electric field

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95462/1/jgra18089.pd

An original growth mode of MWCNTs on alumina supported iron catalysts

Multi-walled carbon nanotubes (MWCNTs) have been produced from ethylene by Fluidized Bed Catalytic Chemical Vapor Deposition (FB-CCVD) on alumina supported iron catalyst powders. Both catalysts and MWCNTs-catalyst composites have been characterized by XRD, SEM-EDX, TEM, Mössbauer Spectroscopy, TGA and nitrogen adsorption measurements at different stages of the process. The fresh catalyst is composed of amorphous iron (III) oxide nanoparticles located inside the porosity of the support and of a micrometric crystalline &-iron (III) oxide surface film. The beginning of the CVD process provokes a brutal reconstruction and simultaneous carburization of the surface film that allows MWCNT nucleation and growth. These MWCNTs grow aligned between the support and the surface catalytic film, leading to a uniform consumption and uprising of the film. When the catalytic film has been consumed, the catalytic particles located inside the alumina porosity are slowly reduced and activated leading to a secondary MWCNT growth regime, which produces a generalized grain explosion and entangled MWCNT growth. Based on experimental observations and characterizations, this original two-stage growth mode is discussed and a general growth mechanism is proposed

Associations of ostracods in shallow lakes in the northeast of La Pampa province (Argentina)

Los lagos someros son frecuentes en La Pampa. Aunque muchas características de su biota son conocidas, la información sobre la distribución y ecología de los ostrácodos es escasa, a pesar de su importancia como indicadores biológicos y en actuopaleontología. El objetivo de este estudio es conocer la composición taxonómica, la densidad de ostrácodos y sus relaciones con parámetros ambientales en lagos del noreste de La Pampa. Se estudiaron cinco lagos desde septiembre de 2016 hasta marzo de 2017. Se tomaron muestras de sedimentos superficiales e in situ se midieron: conductividad, temperatura y transparencia y se tomaron muestras para determinar salinidad, pH y composición iónica. Los lagos difirieron en su salinidad, composición iónica y transparencia. Se registraron diez taxa, algunos hallados previamente en la provincia de Buenos Aires (Heterocypris similis, Heterocypris incongruens, Cypridopsis vidua y Chlamydotheca incisa), la cuenca de Llancanelo (H. incongruens y C. vidua) y lagos del norte de Patagonia (C. incisa, C. vidua, Potamocypris unicaudata, H. incongruens y Amphicypris argentiniensis). Se comprobó la influencia de la salinidad ya que algunas especies (A. argentinensis, Limnocythere rionegroensis y Limnocythere titicaca) se encontraron sólo en el lago más salino. La existencia en La Pampa de tres ecorregiones diferentes (Llanura Pampeana, Espinal y Estepa Patagónica) y la presencia en los lagos estudiados de ostrácodos del noroeste argentino (L. titicaca), de la llanura bonaerense (H. similis, H. incongruens) y otras de Patagonia (L. rionegroensis), permitiría afirmar que los lagos de La Pampa están en una zona de transición entre faunas diferentes.Shallow lakes are common in the center of Argentina. Although many characteristics of its biota are known, information on the distribution and ecology of ostracods is scarce despite their importance as biological indicators and in actuopaleontology. The objective of this study was to determine the taxonomic composition, the density of ostracods, and their relationships with environmental parameters in lakes in the northeast of La Pampa. Five aquatic ecosystems were studied from September 2016 to March 2017. Samples of superficial sediments were collected, and conductivity, temperature, and transparency were measured in situ. Water samples were collected to determine salinity, pH, and ionic composition. The lakes differed in salinity, ionic composition, and transparency. Ten taxa were registered, some previously found in the province of Buenos Aires (Heterocypris similis, Heterocypris incongruens, Cypridopsis vidua, and Chlamydotheca incisa), the Llancanelo basin (H. incongruens and C. vidua), and North Patagonia lakes (C. incisa, C. vidua, Potamocypris unicaudata, H. incongruens, and Amphicypris argentiniensis). The influence of salinity was verified because some species (A. argentinensis, Limnocythere rionegroensis, and Limnocythere titicaca) were found only in the most saline lake. The existence in La Pampa of three different ecoregions (Pampean Plains, Espinal, and Patagonian Steppe) and the presence of ostracods in the studied lakes of northwestern Argentina (L. titicaca), the Buenos Aires province plain (H. similis, H. incongruens), and Patagonia (L. rionegroensis) allowed for affirming that the lakes of La Pampa are in a transition zone among different ostracods faunas.Fil: Kihn, Romina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Echaniz, Santiago Andrés. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Vignatti, Alicia María. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Cabrera, Gabriela Cecilia. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Stella, Cesar A.. Museo Provincial de Ciencias Naturales; Argentin

Temporal evolution of the transpolar potential after a sharp enhancement in solar wind dynamic pressure

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95384/1/grl23891.pd

Diversity of zooplankton in aquatic ecosystems of the northeast of La Pampa (Argentina) with emphasis on new species registered for the province

En la región noreste de la provincia de La Pampa existe una gran cantidad de ecosistemas acuáticos muy heterogéneos, sin embargo los estudios limnológicos sobre ellos son escasos. El objetivo es describir la composición del zooplancton de cinco cuerpos de agua y reportar la presencia de seis especies no registradas en la provincia. Entre 2016 y 2017 se tomaron muestras en dos pequeños lagos (“ojos de agua”) subsalinos, de alta transparencia, con vegetación arraigada y en tres lagunas sub o hiposalinas, sin vegetación y menor transparencia. Se registraron ocho cladóceros, nueve copépodos y 27 rotíferos. En todos los casos los rotíferos dominaron en número de especies y densidad pero las comunidades zooplanctónicas de los ojos de agua fueron diferentes de las de las lagunas. Los ambientes estudiados están en un área geográfica reducida, pero su diversidad fue mayor que la encontrada en áreas más extensas de La Pampa, lo que puede deberse a la heterogeneidad de los ecosistemas acuáticos incluidos en este estudio. Tres copépodos (Argyrodiaptomus bergi, Boeckella bergi y Eucyclops neumani) y tres rotíferos (Euchlanis dilatata, Lecane closterocerca y Plationus patulus) son citados por primera vez para la provincia de La Pampa. Este estudio confirma que la distribución de A. bergi y E. neumani es más amplia que la conocida hasta ahora, restringida a Brasil y la cuenca del Paraná - del Plata, pero el resto son especies extensamente distribuidas en Argentina. En consecuencia, la falta de información en La Pampa se debió a la ausencia de investigaciones previas.The northeastern region of La Pampa province has a large number of heterogenic aquatic ecosystems; however, limnological studies of these ecosystems are scarce. The objective of this study is to describe the composition of the zooplankton of five water bodies and report the presence of six species not previously registered in the province. Between 2016 and 2017, samples were taken in two small, highly transparent subsaline lakes (“water holes”) with rooted vegetation and in three sub- or hyposaline shallow lakes, without vegetation and with less transparency. Eight cladocerans, nine copepods, and 27 rotifers were recorded. In all cases, rotifers dominated in number of species and density, but the zooplankton communities of the water holes differed from those of the shallow lakes. The aquatic ecosystems studied are in a reduced geographic area, but their diversity was greater than that of larger areas of La Pampa, which may be due to the heterogeneity of the water bodies included in this study. Three copepods (Argyrodiaptomus bergi, Boeckella bergi, and Eucyclops neumani) and three rotifers (Euchlanis dilatata, Lecane closterocerca, and Plationus patulus) have been identified for the first time in La Pampa province. This study confirms that the distribution of A. bergi and E. neumani is wider than known so far, which was restricted to Brazil and the Paraná - del Plata basin, but the remaining zooplankton are species widely distributed in Argentina. Thus, the lack of information in La Pampa was due to the absence of previous investigations.Fil: Echaniz, Santiago Andrés. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Vignatti, Alicia María. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Cabrera, Gabriela Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Kihn, Romina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Stella, Cesar A.. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentin

Attribution and contestation: Relations between elites and other social groups

In this article we explore the often ambiguous relations between elites and other social groups, both subordinate and of relatively equal standing. The article draws on two distinctive ethnographic cases: the white Franco-Mauritian elite, and the expert elite of management consultants in a Western European context. Our analysis of the two cases provides insights into how the power and status of elites is both contested and attributed by the people they interact with and relate to in concrete, yet substantially different contexts and situations. The aim is to show how the position and power of different kinds of elites is relationally negotiated and achieved. As we argue, a better understanding of the role of other social groups in the attribution, maintenance and contestation of status is relevant for understanding both more traditional economic elites and expert elites without tight networks

Applications of yeast flocculation in biotechnological processes

A review on the main aspects associated with yeast flocculation and its application in biotechnological processes is presented. This subject is addressed following three main aspects – the basics of yeast flocculation, the development of “new” flocculating yeast strains and bioreactor development. In what concerns the basics of yeast flocculation, the state of the art on the most relevant aspects of mechanism, physiology and genetics of yeast flocculation is reported. The construction of flocculating yeast strains includes not only the recombinant constitutive flocculent brewer’s yeast, but also recombinant flocculent yeast for lactose metabolisation and ethanol production. Furthermore, recent work on the heterologous β-galactosidase production using a recombinant flocculent Saccharomyces cerevisiae is considered. As bioreactors using flocculating yeast cells have particular properties, mainly associated with a high solid phase hold-up, a section dedicated to its operation is presented. Aspects such as bioreactor productivity and culture stability as well as bioreactor hydrodynamics and mass transfer properties of flocculating cell cultures are considered. Finally, the paper concludes describing some of the applications of high cell density flocculation bioreactors and discussing potential new uses of these systems.Fundação para a Ciência e a Tecnologia (FCT) – PRAXIS XXI - BD11306/97