2,064 research outputs found

    About identification of features that affect the estimation of citrus harvest

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    Accurate models for early harvest estimation in citrus production generally involve expensive variables. The goal of this research work was to develop a model to provide early and accurate estimations of harvest using low-cost features. Given the original data may derive from tree measurements, meteorological stations, or satellites, they have varied costs. The studied orchards included tangerines (Citrus reticulata x C. sinensis) and sweet oranges (C. sinensis) located in northeastern Argentina. Machine learning methods combined with different datasets were tested to obtain the most accurate harvest estimation. The final model is based on support vector machines with low-cost variables like species, age, irrigation, red and near-infrared reflectance in February and December, NDVI in December, rain during ripening, and humidity during fruit growth. Highlights: Red and near-infrared reflectance in February and December are helpful values to predict orange harvest. SVM is an efficient method to predict harvest. A ranking method to A ranking-based method has been developed to identify the variables that best predict orange production.  Accurate models for early harvest estimation in citrus production generally involve expensive variables. The goal of this research work was to develop a model to provide early and accurate estimations of harvest using low-cost features. Given the original data may derive from tree measurements, meteorological stations, or satellites, they have varied costs. The studied orchards included tangerines (Citrus reticulata x C. sinensis) and sweet oranges (C. sinensis) located in northeastern Argentina. Machine learning methods combined with different datasets were tested to obtain the most accurate harvest estimation. The final model is based on support vector machines with low-cost variables like species, age, irrigation, red and near-infrared reflectance in February and December, NDVI in December, rain during ripening, and humidity during fruit growth. Highlights: Red and near-infrared reflectance in February and December are helpful values to predict orange harvest. SVM is an efficient method to predict harvest. A ranking method to A ranking-based method has been developed to identify the variables that best predict orange production

    Diet of the Kelp Gull (Larus dominicanus) during the breeding season in the Bahía Blanca Estuary, Buenos Aires, Argentina

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    La Gaviota Cocinera (Larus dominicanus) está ampliamente distribuida en Argentina. Es una especie de comportamiento alimentario generalista y oportunista; según algunos autores, su capacidad de explotar recursos alimentarios derivados de actividades humanas ha favorecido su expansión geográfica. En este estudio se da a conocer la dieta de la Gaviota Cocinera durante el período reproductivo en una colonia de 3114 nidos ubicada en la Isla del Puerto, estuario de Bahía Blanca, provincia de Buenos Aires, Argentina. Se analizó un total de 1024 egagrópilas, cinco regurgitados de pichones y 12 de volantones, recolectados entre los meses de octubre y diciembre de 2003. Se registraron 39 categorías presa, de las cuales los granos (principalmente girasol) y la carroña de ganado vacuno tuvieron los mayores porcentajes en la dieta (54.6% y 29.0%, respectivamente). Ambos recursos están disponibles en grandes cantidades en las cercanías de la colonia, lo que podría estar favoreciendo el incremento poblacional observado en los últimos años. Otras presas halladas en la dieta, en orden decreciente de ocurrencia, fueron peces óseos, gasterópodos, insectos, cirripedios, basura, quitones, pelecípodos, roedores y otros. En la colonia de la Isla del Puerto, al igual que lo observado en otras colonias de la costa patagónica, la Gaviota Cocinera se comportaría como una especie generalista, con una fuerte tendencia a la explotación de recursos de origen humano y, en menor medida, de presas del ambiente marino costero.The Kelp Gull (Larus dominicanus) is widely distributed in Argentina. Several authors suggest that the species is expanding its geographic distribution due to its capacity to exploit food resources derived from human activities. This study shows the diet composition of the Kelp Gull during breeding season in a colony of 3114 nests located in the Del Puerto Island, Bahía Blanca estuary, Buenos Aires Province, Argentina. A total of 1024 pellets, five chick regurgitates, and 12 fledgling regurgitates collected between October and December 2003 were analyzed. A total of 39 prey categories were recorded, being grains (mainly sunflower) and cattle carrion the most important items (54.6% and 29.0%, respectively). These prey items are available in large quantities in the proximity of the colony, which could favour the population increase observed in the last years. Fishes, marine snails, insects, barnacles, garbage, chitons, mussels, clams, and rodents were also observed. Gulls from this colony, as in other colonies along the Patagonian coast, are generalists with a strong tendency to the exploitation of human-derived resources and, to a lesser degree, of seashore preys

    Photoreduction of anthracenes catalyzed by peri ‐xanthenoxanthene: a scalable and sustainable Birch‐type alternative

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    The typical Birch reduction transforms arenes into cyclohexa‐1,4‐dienes by using alkali metals, an alcohol as a proton source, and an amine as solvent. Capitalizing on the strong photoreductive properties of peri‐xanthenoxanthene (PXX), herein we report the photocatalyzed “Birch‐type” reduction of acenes by employing visible blue light irradiation at room temperature in the presence of air. Upon excitation at 405 or 460 nm in the presence of a mixture of N, N‐diisopropylethylamine (DIPEA) and trifluoromethanesulfonimide (HNTf2) in DMSO, PXX photocatalyzes the selective reduction of full‐carbon acene derivatives (24–75 %). Immobilization of PXX onto polydimethylsiloxane (PDMS) beads (PXX‐PDMS) allowed the use of the catalyst in heterogeneous batch reactions, giving 9‐phenyl‐9,10‐dihydroanthracene in high yield (68 %). The catalyst could easily be recovered and reused, with no notable drop in performance observed after five reaction cycles. Integration of the PXX‐PDMS beads into a microreactor enabled the reduction of acenes under continuous‐flow conditions, thereby validating the sustainability and scalability of this heterogeneous‐phase approach

    Técnicas de inteligencia artificial aplicadas a problemas de visión por computadora

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    El Aprendizaje Automatizado (AA) es uno de los campos científicos y técnicos de más rápido crecimiento en la actualidad. Está situado en el núcleo de la inteligencia artificial y ciencia de datos. Sus técnicas han surgido como las más elegidas para dar solución a problemas en distintas disciplinas. Una de ellas es la visión por computadora cuya finalidad es crear modelos del mundo real a partir de imágenes. Entre las tareas más importantes de esta disciplina están la detección de puntos claves faciales, el reconocimiento de emociones humanas y la detección de plagas en cultivos. El presente proyecto tiene como objetivo el desarrollo de nuevos algoritmos basados en AA que permitan realizar estas tareas en forma automática.Eje: Agentes y Sistemas Inteligentes.Red de Universidades con Carreras en Informátic

    Multicentre, randomised, open-label, phase IV-III study to evaluate the efficacy of cloxacillin plus fosfomycin versus cloxacillin alone in adult patients with methicillin-susceptible Staphylococcus aureus bacteraemia: Study protocol for the SAFO trial

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    Introduction Methicillin-susceptible Staphylococcus aureus (MSSA) bacteraemia is a frequent condition, with high mortality rates. There is a growing interest in identifying new therapeutic regimens able to reduce therapeutic failure and mortality observed with the standard of care of beta-lactam monotherapy. In vitro and small-scale studies have found synergy between cloxacillin and fosfomycin against S. aureus. Our aim is to test the hypothesis that cloxacillin plus fosfomycin achieves higher treatment success than cloxacillin alone in patients with MSSA bacteraemia. Methods We will perform a superiority, randomised, open-label, phase IV-III, two-armed parallel group (1:1) clinical trial at 20 Spanish tertiary hospitals. Adults (=18 years) with isolation of MSSA from at least one blood culture =72 hours before inclusion with evidence of infection, will be randomly allocated to receive either cloxacillin 2 g/4-hour intravenous plus fosfomycin 3 g/6-hour intravenous or cloxacillin 2 g/4-hour intravenous alone for 7 days. After the first week, sequential treatment and total duration of antibiotic therapy will be determined according to clinical criteria by the attending physician. Primary endpoints: (1) Treatment success at day 7, a composite endpoint comprising all the following criteria: patient alive, stable or with improved quick-Sequential Organ Failure Assessment score, afebrile and with negative blood cultures for MSSA at day 7. (2) Treatment success at test of cure (TOC) visit: patient alive and no isolation of MSSA in blood culture or at another sterile site from day 8 until TOC (12 weeks after randomisation). We assume a rate of treatment success of 74% in the cloxacillin group. Accepting alpha risk of 0.05 and beta risk of 0.2 in a two-sided test, 183 subjects will be required in each of the control and experimental groups to obtain statistically significant difference of 12% (considered clinically significant). Ethics and dissemination Ethical approval has been obtained from the Ethics Committee of Bellvitge University Hospital (AC069/18) and from the Spanish Medicines and Healthcare Product Regulatory Agency (AEMPS, AC069/18), and is valid for all participating centres under existing Spanish legislation. The results will be presented at international meetings and will be made available to patients and funders. © Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ

    Extremely Long-Lived Stigmas Allow Extended Cross-Pollination Opportunities in a High Andean Plant

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    High-elevation ecosystems are traditionally viewed as environments in which predominantly autogamous breeding systems should be selected because of the limited pollinator availability. Chaetanthera renifolia (Asteraceae) is an endemic monocarpic triennial herb restricted to a narrow altitudinal range within the high Andes of central Chile (3300–3500 m a.s.l.), just below the vegetation limit. This species displays one of the larger capitulum within the genus. Under the reproductive assurance hypothesis, and considering its short longevity (monocarpic triennial), an autogamous breeding system and low levels of pollen limitation would be predicted for C. renifolia. In contrast, considering its large floral size, a xenogamous breeding system, and significant levels of pollen limitation could be expected. In addition, the increased pollination probability hypothesis predicts prolonged stigma longevity for high alpine plants. We tested these alternative predictions by performing experimental crossings in the field to establish the breeding system and to measure the magnitude of pollen limitation in two populations of C. renifolia. In addition, we measured the stigma longevity in unpollinated and open pollinated capitula, and pollinator visitation rates in the field. We found low levels of self-compatibility and significant levels of pollen limitation in C. renifolia. Pollinator visitation rates were moderate (0.047–0.079 visits per capitulum per 30 min). Although pollinator visitation rate significantly differed between populations, they were not translated into differences in achene output. Finally, C. renifolia stigma longevity of unpollinated plants was extremely long and significantly higher than that of open pollinated plants (26.3±2.8 days vs. 10.1±2.2, respectively), which gives support to the increased pollination probability hypothesis for high-elevation flowering plants. Our results add to a growing number of studies that show that xenogamous breeding systems and mechanisms to increase pollination opportunities can be selected in high-elevation ecosystems

    Sequencing of diverse mandarin, pummelo and orange genomes reveals complex history of admixture during citrus domestication

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    Cultivated citrus are selections from, or hybrids of, wild progenitor species whose identities and contributions to citrus domestication remain controversial. Here we sequence and compare citrus genomes-a high-quality reference haploid clementine genome and mandarin, pummelo, sweet-orange and sour-orange genomes-and show that cultivated types derive from two progenitor species. Although cultivated pummelos represent selections from one progenitor species, Citrus maxima, cultivated mandarins are introgressions of C. maxima into the ancestral mandarin species Citrus reticulata. The most widely cultivated citrus, sweet orange, is the offspring of previously admixed individuals, but sour orange is an F1 hybrid of pure C. maxima and C. reticulata parents, thus implying that wild mandarins were part of the early breeding germplasm. A Chinese wild 'mandarin' diverges substantially from C. reticulata, thus suggesting the possibility of other unrecognized wild citrus species. Understanding citrus phylogeny through genome analysis clarifies taxonomic relationships and facilitates sequence-directed genetic improvement. (Résumé d'auteur

    La Ingeniería Automotriz clave para el desarrollo sostenible de Ecuador

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    El presente texto es una contribución al desarrollo de la sostenibilidad ecuatoriana y mantiene el debate sobre temas del estudio de la Ingeniería Automotriz. El mérito del libro radica en una triple condición: alimenta la investigación académica ecuatoriana, contribuye a llenar el vacío de producción científica automotriz direccionada a las necesidades del Ecuador y reconoce el esfuerzo de los investigadores que se dedican a la producción académica técnica. La Universidad Politécnica Salesiana —en su sede Guayaquil— realizó en 2018, las Segundas Jornadas Científicas de Ingeniería Automotriz; este texto es el producto final de ese evento académico, cuyas memorias técnicas son constituidas por ocho resultados de investigaciones en Ingeniería Automotriz que aportarán desarrollo sostenible al Ecuador en áreas como: el diseño, el control de contaminación, la eficiencia energética y la movilidad. Este recorrido por varias ramas de la Ingeniería Automotriz muestra al lector múltiples aplicaciones y cambios de paradigmas en la industria; no somos solamente consumidores de tecnología, somos también productores de la misma. Este texto da cuenta del desarrollo de la industria automotriz ecuatoriana. Ing. Renato Fierro J. MSc

    Categorización del estado de conservación de las lagartijas y anfisbenas de la República Argentina

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    Luego de la elaboración de la primera lista roja de la herpetofauna de la República Argentina, realizada en el año 2000, son numerosos los cambios y estudios efectuados en los diferentes grupos de saurios de la Argentina. Si bien hay avances realizados en todas las ramas de la biología relacionadas a las lagartijas, los progresos taxonómicos y ecológicos son los más evidentes. Debido a estos progresos, y a la implementación de sustanciales modificaciones con respecto a la metodología que se utilizara en el año 2000, un grupo de veintisiete especialistas de diferentes instituciones académicas de la Argentina aportaron información biológica, ecológica, geográfica y taxonómica en un taller que permitió reevaluar el estado de conservación de las 256 especies de lagartijas y anfisbenas de la Argentina. Los resultados obtenidos indican que setenta y ocho especies se encuentran incluidas en la lista roja (una En Peligro, nueve Amenazadas y 68 Vulnerables), 31 Insuficientemente Conocidas y 147 No Amenazadas. Con respecto a la categorización anterior de la AHA, se agregaron 94 especies, de las cuales 87 son nuevos taxa, cuatro revalidadas, y otras tres especies fueron incorporadas a la fauna argentina. Asimismo cinco especies fueron extraídas del listado de la fauna de la República Argentina. En comparación con los resultados obtenidas en la categorización del año 2000, observamos que el número de especies Amenazadas se incrementó de cinco a nueve especies y de siete a 68 especies como Vulnerable, incluyendo a los géneros Phymaturus y Anisolepis. Asimismo, se categorizó como Insuficientemente Conocida a 31 especies contra 108 del año 2000. Estos resultados son en parte debido al incremento en el conocimiento sistemático, biológico, ecológico y biogeográficos de las lagartijas y anfisbenas de la Argentina, por el cambio radical de la metodología utilizada y también por los efectos de la presión antrópica sobre las especies y/o sus habitats.After the first herpetofaunal red list for Argentina, which was published in the year 2000, there had been numerous changes and studies made on different groups of lizards from Argentina. Although there had been contributions in all areas of lizard biology, those made in taxonomy and ecology are the most evident. Due to these and the implementation of substantial modifications with respect to the methodology used in the year 2000, a group of twenty-seven specialists from different Argentinian institutions contributed biological, ecological, geographic and taxonomic information to a workshop that allowed re-evaluation of the conservation status of the 256 lizard and amphisbaenian species from Argentina. Results indicate that 78 species are included in the red list (one Endangered, nine Threatened, and 68 Vulnerable), 31 are insufficiently known and 147 Non-threatened. Compared with the previous AHA categorization, 94 new species have been added, of which 87 are new taxa, four re-validations, and three species were incorporated to the Argentina fauna; five species were deleted from the Argentina list. Compared with the 2000 yr results, threatened species increased from five to nine species, and vulnerable species increased from seven to 68, including all species of the genera Phymaturus and Anisolepis. There are 31 species considered as insufficiently known against 108 listed in this category in 2000. These results are partially based on the increase in systematic, biological, ecological and biogeographical knowledge of lizards and amphisbaenians, and by the radical change in methodology and by effects of anthropogenic pressure on species and/or their habitats.Asociación Herpetológica Argentin
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