261 research outputs found

    Comparative Studies of Two Flax (Linum usitatissimum) Cultivars for Stomatal Characteristics, Adaxial Stomatal Resistance, and Osmotic Potential

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    Limitations on seed yield of flax (Linum usitatissimum L.) are a major concern of re searchers trying to develop higher yielding oilseed cultivars (37, 71). Dybing (37) stated that comparative studies of physiological and biochemical factors could provide necessary insight into the cause of these limitations. Based on repeated observations and yield trials of lines from the world collection, CI 2522 (\u27Linott\u27) and CI 1194 (Grant) were selected as an appropriate pair for such studies (37). The basic criteria of selection of these two cultivars were a consistent difference in seed yield cross environments tested and similarities in such categories as disease resistance, agronomic type, morphology, flowering habit, fruiting habit, and flowering date (37). During yield trials, Linott was consistently higher yielding than Grant. Although Grant expresses susceptibility to a North American race of rust (Melanpsora lini) and Linott does not, this factor was not responsible for the yield differences observed during the yield trials (37). Yield components data have indicated that the greater yield capacity of Linott stems from its ability to maintain more sinks, either as seeds per boll or bolls per area, than Grant (71). Comparison of Linott and Grant for total dry weight, period of main boll production (71), and net CO2 exchange rate (37) failed to show any differences that would explain the different yield potentials. Seed production in flax is very sensitive to environment al factors such as temperature and soil moisture level (42). Yet the crop is grown in areas of medium to low rainfall. Therefore, it was decided that ffurther comparative studies in Linott and Grant should include water relations. Stomatal characteristics, stomatal resistance, and osmotic potential were chosen as the areas that would be studied to determine if differences exist that could help to explain the difference in yield potential of Linott and Grant

    Archeota, Spring 2018

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    https://scholarworks.sjsu.edu/saasc_archeota/1007/thumbnail.jp

    Parental breeding decisions and genetic quality predict social structure of independent offspring

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    Across the animal kingdom, newly independent juveniles form social associations that influence later fitness, mate choice and gene flow, but little is known about the ontogeny of social environments, particularly in wild populations. Here we test whether associations among young animals form randomly or are influenced by environmental or genetic conditions established by parents. Parents' decisions determine natal birth sites, which could affect who independent young initially encounter; secondly, mate choice determines genetic condition (e.g. inbreeding) of young and the parental care they receive, which can affect sociability. However, genetic and environmental factors are confounded unless related offspring experience different natal environments. Therefore, we used a long-term genetic pedigree, breeding records and social network data from three cohorts of a songbird with high extra-pair paternity (hihi, Notiomystis cincta) to disentangle (1) how nest location and relatedness contribute to association structure once juveniles disperse away from birth sites, and (2) if juvenile and/or parental inbreeding predicts individual sociability. We detected positive spatial autocorrelation: hihi that fledged closer by were more likely to associate even after dispersing, irrespective of genetic relatedness. Juvenile inbreeding did not predict sociability, but those raised by more inbred fathers formed more, stronger, associations, which did not depend on whether that male was the genetic parent or not. These results suggest that the natal environment created by parents, rather than focal genetic condition, establishes the foundation for social associations. Overall, we highlight how social inheritance may play an important role in population dynamics and evolutionary potential in wild animals

    Tracking the Functions of AI as Paradata & Pursuing Archival Accountability

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    While a familiar term in fields like social science research and digital cultural heritage, \u27paradata\u27 has not yet been introduced conceptually into the archival realm. In response to an increasing number of experiments with machine learning and artificial intelligence, the InterPARES Trust AI research group proposes the definition of paradata as \u27information about the procedure(s) and tools used to create and process information resources, along with information about the persons carrying out those procedures.\u27 The utilization of this concept in archives can help to ensure that AI-driven systems are designed from the outset to honor the archival ethic, and to aid in the evaluation of off-the-shelf automation solutions. An evaluation of current AI experiments in archives highlights opportunities for paradata-conscious practice

    Detection of Anaplasma Marginale Theiler, 1909 in Tick Gut Homogenates Using a Microfluorometric Immunoassay

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    This study is concerned with the detection of Anaplasma marginale organisms in gut homogenates of adult Dermacentor andersoni that were infected as nymphs. Various techniques are attempted using a microimmunofluorescence method.Veterinary Parasitolog

    Efecto de concentración de sólidos en la temperatura de ebullición de la leche de cabra y vaca

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    En este estudio se determina el aumento ebulloscopio que presenta  la leche de vaca y cabra a dos concentraciones (entera y evaporada) en un rango de concentraciones  9,9 °Brix y 12,9 °Brix para leche entera; y 24,9°Brix y 25,3 para leche evaporada, y a presiones desde  0,4 hasta 0,9 bar (abs). La regla de Dühring logra representar la temperatura de ebullición de cada solución frente a la del agua a la misma presión, se obtiene una línea recta. Estos resultados se compararon con la expresión general dada por Ibarz (2005) con lo que se determinó que guarda una tendencia lógica a lo establecido por la teoría de evaporación que explica que la temperatura de ebullición de una solución aumenta conforme existe mayor concentración de sólidos en la leche, así como cuando se varia la presión

    Avian influenza virus (H11N9) in migratory shorebirds wintering in the Amazon region, Brazil

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    Aquatic birds are the natural reservoir for avian influenza viruses (AIV). Habitats in Brazil provide stopover and wintering sites for water birds that migrate between North and South America. The current study was conducted to elucidate the possibility of the transport of influenza A viruses by birds that migrate annually between the Northern and Southern Hemispheres. In total, 556 orotracheal/cloacal swab samples were collected for influenza A virus screening using real-time RT-PCR (rRT-PCR). The influenza A virus-positive samples were subjected to viral isolation. Four samples were positive for the influenza A matrix gene by rRT-PCR. From these samples, three viruses were isolated, sequenced and characterized. All positive samples originated from a single bird species, the ruddy turnstone (Arenaria interpres), that was caught in the Amazon region at Caeté Bay, Northeast Pará, at Ilha de Canelas. To our knowledge, this is the first isolation of H11N9 in the ruddy turnstone in South America. (Résumé d'auteur

    Exceptional freshening and cooling in the eastern subpolar North Atlantic caused by reduced Labrador Sea surface heat loss

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    Observations of the eastern subpolar North Atlantic in the 2010s show exceptional freshening and cooling of the upper ocean, peaking in 2016 with the lowest salinities recorded for 120 years. Published theories for the mechanisms driving the freshening include: reduced transport of saltier, warmer surface waters northwards from the subtropics associated with reduced meridional overturning; shifts in the pathways of fresher, cooler surface water from the Labrador Sea driven by changing patterns of wind stress; and the eastward expansion of the subpolar gyre. Using output from a high-resolution hindcast model simulation, we propose that the primary cause of the exceptional freshening and cooling is reduced surface heat loss in the Labrador Sea. Tracking virtual fluid particles in the model backwards from the eastern subpolar North Atlantic between 1990 and 2020 shows the major cause of the freshening and cooling to be an increased outflow of relatively fresh and cold surface waters from the Labrador Sea; with a minor contribution from reduced transport of warmer, saltier surface water northward from the subtropics. The cooling, but not the freshening, produced by these changing proportions of waters of subpolar and subtropical origin is mitigated by reduced along-track heat loss to the atmosphere in the North Atlantic Current. We analyse modelled boundary exchanges and water mass transformation in the Labrador Sea to show that since 2000, while inflows of lighter surface waters remain steady, the increasing output of these waters is due to reduced surface heat loss in the Labrador Sea beginning in the early 2000s. Tracking particles further upstream reveals that the primary source of the increased volume of lighter water transported out of the Labrador Sea is increased recirculation of water, and therefore longer residence times, in the upper 500–1000 m of the subpolar gyre
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