256 research outputs found

    Breeding Perennial Warm-Season Grasses for the Subtropical Belt in South America

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    Perennial warm-season grasses share several agronomic characteristics, such as marked seasonal growth, cold susceptibility and photoperiod sensitivity. Breeding efforts in South America have been focused on attempting to improved cool-season growth, cold tolerance and also adaptation to the alternation of flooding and drought periods. Warm-season grasses also have in common that most of them are polyploid and some have very low fertility. Apomixis is also a common trait among these species. For polyploid species with limited seed yield, which commonly have stolons or rhizomes, F1 hybrids are created and released as cultivars. Acroceras macrum and Hemarthria altissima will be used as examples. For polyploid species without seed fertility issues, such as Setaria sphacelta, recurrent phenotypic selection (RPS) is used to generate improved populations adapted to these transition zones. For polyploid and apomitic species, such as Paspalum spp. and Brachiara spp., several breeding approaches are now available. The generation of F1 apomictic hybrids is currently used. It has been recently observed that the efficiency of this breeding method can be improved if the genetic distance among parents is considered. There is also new information indicating the great potential of using apomixis-linked molecular markers for the early identification of apomictic hybrids. Population-breeding approaches, such as RPS and selection based on combining ability, can also be used to assess the generation of superior apomictic hybrids. Finally, the challenge of breeding perennial warm-season grasses for the subtropics mainly relates to improving adaptation to extreme conditions (cold winters and warm summers and alternation of flooding and drought), developing specific breeding techniques for polyploid or apomictic species

    Seasonal Expression of Apospory in Bahiagrass

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    Flowering plants can reproduce sexually (outcrossing and/or selfing) and/or asexually. Sexual reproduction implies the successful completion of meiosis and double fertilisation for the formation of both the embryo and the endosperm. In contrast, gametophytic apomixis is an asexual mode of reproduction through seeds that involves parthenogenetic embryo development from a cytologically unreduced egg cell (2n). Apospory is the process by which unreduced gametophytes are formed after a series of mitotic divisions of somatic cells (2n) in the ovary. This occurs independently from the sexual meiotic process; and therefore, both sexual and apomictic pathways may coexist simultaneously. Apospory is inherited in bahiagrass (Paspalum notatum) as a single dominant Mendelian factor with distorted segregation (Martínez et al. 2001), and its degree of expression was reported to vary throughout the flowering season in P. cromyorrhizon, a close relative of bahiagrass (Quarin 1986). Bahiagrass is a perennial warm-season grass widely used for forage and utility turf in the south-eastern US due to its persistence in sandy, infertile soils. Diploid races reproduce sexually and are highly self-incompatible (Acuña et al. 2007), while polyploids are classified as pseudogamous apomicts (pollination is required) (Quarin 1999). Sexual tetraploid genotypes have been experimentally created (Quesenberry and Smith 2003; Quesenberry et al. 2010) and successfully used in crosses (Acuña et al. 2009). Cytoembryological analysis has been used to determine the mode of reproduction in bahiagrass (Martínez et al. 2001; Acuña et al. 2007). At anthesis, sexual plants produce spikelets having only a single Polygonum type meiotic embryo sac (SES), characterised by bearing the egg apparatus close to the micropyla, a large binucleated central cell and a group of antipodal cells at the chalazal end (Figure 1a). Highly apomictic plants produce ovules having single or multiple aposporous embryo sacs (AES), which present the egg apparatus and a central cell with 2 polar nuclei, and no antipodal cells (Figure 1b). Some tetraploid bahiagrass races are also able to produce ovules that have the sexual meiotic megasporocyte together with one or more aposporous sacs (AES+SES), and these plants are classified as facultative apomictic. The objective of this study was to characterise the reproductive mode of 5 wild dwarf bahiagrasses, a highly apomictic hybrid (Acuña et al. 2009) and the cultivar ‘Argentine’ at different times during the flowering season and under different nitrogen (N) fertiliser rates

    Selección de genotipos por comportamiento forrajero a partir de una progenie F2 de stylosanthes guianensis (fabaceae)

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    Stylosanthes guianensis (Aubl.) Sw. es una especie autógama de gran importancia forrajera en el norte de Argentina, ya que estudios previos han mostrado que se adapta bien a diferentes tipos de suelos y ambientes, siendo poco exigente en requerimientos de fósforo, además, tienen buen valor nutritivo comparado con otras especies tropicales. En Corrientes se han evaluado algunos de los cultivares comerciales, observándose una buena producción media durante 4 años. Sin embargo, la producción en período frío disminuye o se produce la muerte de las plantas debido a las bajas temperaturas. Sería de gran interés incorporar a Stylosanthes guianensis a un programa de mejoramiento genético. Con la finalidad de obtener genotipos que produjeran durante todo el año, sean tolerantes a las heladas y con mayor vigor. Con respecto a este punto, la cátedra de Forrajicultura de FCA UNNE cuenta con germoplasma de cuatro cultivares de S. guianensis (Endavour, Cook, CIAT 184 y Graham), los cuales fueron cultivados y caracterizados previamente. El objetivo del presente trabajo fue identificar y seleccionar genotipos deseables a partir de progenies segregantes (F2), provenientes de la hibridación de cultivares comerciales de Stylosanthes guianensis. Para ello se dispuso de un total de 390 plantas a campo, distribuidas en un diseño en bloques completos al azar con 3 repeticiones. Se realizaron mediciones relativas a la producción primaria, altura de plantas y diámetro, susceptibilidad a las enfermedades, tolerancia al frío y producción de semillas, como así también a observaciones del hábito de crecimiento y porte de la planta. Los resultados permiten identificar genotipos altamente favorables desde el punto de vista de la tolerancia al frío principalmente, logrando sobrevivir al invierno un total de 15 genotipos F2, pertenecientes a 8 familias, pero además 16 genotipos de padres o variedades comerciales. Lo cual daría un indicio de la factibilidad de la técnica de mejoramiento empleadaFil: Winter, Jonatan D.. Universidad Nacional del NordesteFil: Acuña, Carlos A.. Universidad Nacional del NordesteFil: Brugnoli, Elsa A.. Universidad Nacional del Nordest

    Design of a Book and Thesis Recommendation System based on Ontologies associated with Thesaurus: The Case of the Libraries of the UNMSM

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    El incremento en el número de libros, textos, tesis y otros hace que los sistemas tradicionales de búsqueda de literatura sobre algún tema en particular sean complejos y lentos, no siempre obteniendo buenos resultados. Peor aún si se trata de recomendar algún libro en particular, basado en el conocimiento de la calidad de su contenido. Este es el caso muy particular de las bibliotecas de la UNMSM, ya que no se cuenta con una ayuda automatizada para la recomendación de libros y tesis físicas.Por ello se propone diseñar e implementar un sistema de recomendación de libros y tesis para las bibliotecas de la UNMSM mediante la técnica de recomendación basada en Ontologías asociada a Tesauros. Se diseñó un modelo ontológico para la recomendación de libros y un modelo de recomendación para las tesis porque el objetivo de la recomendación de ambas literaturas es diferente, mientras la recomendación de libros busca incrementar el conocimiento de los usuarios, la recomendación de tesis ayuda a seleccionar un tema de investigación o encontrar una referencia bibliográfica ajustada al tema de investigación del usuario.The increase in the number of books, texts, theses and others makes traditional search systems of literature on a particular subject are complex and slow, not always obtaining good results. Even worse if it is about recommending a particular book, based on knowledge of the quality of its content. This is the very particular case of the libraries of the UNMSM, since there is no automated help for the recommendation of books and physical theses.Therefore, it is proposed to design and implement a book and thesis recommendation system for UNMSM libraries through the recommendation technique based on Ontologies associated with Thesauri. An ontological model was designed for the recommendation of books and a model of recommendation for the theses because the objective of the recommendation of both literatures is different, while the book recommendation seeks to increase the knowledge of the users, the thesis recommendation helps to select a research topic or find a bibliographic reference adjusted to the topic of user research

    What a transparent Romance language with a Germanic gender-determiner mapping tells us about gender retrieval: Insights from European Portuguese

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    The study of the representation and processing of grammatical gender during language production has encountered mixed results regarding which conditions must be met to observe gender effects and whether these reflect the selection of gender values or competition between elements of agreement. The answer seems to depend on the number of determiners associated with each gender and on the language being explored. The present study aims to assess this issue through three picture-word interference tasks in European Portuguese. This is a transparent Romance language featuring a one-to-one gender-determiner mapping system similar to opaque Germanic languages. Conditions of gender in/congruency between targets and distractors were considered, along with gender transparency and agreement. We observed a gender congruency effect restricted to noun phrases. Importantly, the effect was modulated by transparency, which seems relevant regardless of agreement. To explain the results, we adapted the Dual-Route Model of language comprehension to productionThis work was supported by the Government of Spain, Ministry of Education and Vocational Training, through the Training program for Academic Staff (Ayudas para la Formación del Profesorado Universitario, FPU [FPU16/06983]); the Spanish Ministry of Science and Innovation [research project PID2019-110583GB-I00]; the Galician Government [grant for research groups ED431B 2022/2019]; and the Foundation for Science and Technology of Portugal [IF / 00784/2013 / CP1158 / CT0013]. Finally, the study has also been partially supported by the FCT and the Portuguese Ministry of Science, Technology and Higher Education through national funds and co-financed by FEDER through COMPETE2020 under the PT2020 Partnership Agreement [POCI-01-0145- FEDER-007653]S

    For which infants with viral bronchiolitis could it be deemed appropriate to use albuterol, at least on a therapeutic trial basis?

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    Although there is increasing evidence showing that infants with viral bronchiolitis exhibit a high degree of heterogeneity, a core uncertainty shared by many clinicians is with regard to understanding which patients are most likely to benefit from bronchodilators such as albuterol. Based on our review, we concluded that older infants with rhinovirus (RV) bronchiolitis, especially those with a nasopharyngeal microbiome dominated by Haemophilus influenzae; those affected during nonpeak months or during non-respiratory syncytial virus (RSV) predominant months; those with wheezing at presentation; those with clinical characteristics such as atopic dermatitis or a family history of asthma in a first-degree relative; and those infants infected with RSV genotypes ON1 and BA, have the greatest likelihood of benefiting from albuterol. Presently, this patient profile could serve as the basis for rational albuterol administration in patients with viral bronchiolitis, at least on a therapeutic trial basis, and it could also be the starting point for future targeted randomized clinical trials (RCTs) on the use of albuterol among a subset of infants with bronchiolitis

    Uso de Internet por los farmacéuticos comunitarios de Pontevedra y percepción de su utilidad en la relación con los pacientes

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    OBJETIVO Conocer el impacto de la utilización de Internet en la práctica profesional de los farmacéuticos comunitarios (FC) de Pontevedra, grado de utilización, finalidad del acceso a la información, barreras encontradas y la percepción que tienen de cómo influye en su relación con los pacientes.MÉTODO Estudio observacional descriptivo, transversal, en el que se administró un cuestionario ad hoc a los a FC de Pontevedra, basado en los encontrados en la literatura y adaptado a las características específicas de nuestra profesión y entorno por un grupo de expertos formado por cinco farmacéuticos comunitarios.RESULTADOS Se recogieron 159 cuestionarios (15,7% de los FC de la provincia). Uso profesional: 119 (74,8%) a diario. La información obtenida de Internet es considerada totalmente muy fiable por el 68,6%. Dificultades percibidas: la implantación de la receta electrónica ha restringido la entrada a algunas webs profesionales (71,1%), falta de tiempo en horario de trabajo (66,0%). Utilización de Internet en la relación con los pacientes: la mayoría de los farmacéuticos encuestados (55,3%) dice recibir 1 o 2 veces al mes consultas de pacientes sobre informaciones relacionadas con la salud obtenidas de Internet. El 18,8% de farmacéuticos creen interesante recibir a diario consultas de pacientes por correo electrónico, el 23,3% 1 o 2 veces a la semana, el 17,0% 1 o 2 veces al mes y el 40,9% no desean recibirlas nunca.CONCLUSIÓN Los farmacéuticos comunitarios de Pontevedra reconocen las posibilidades, pero todavía no perciben la utilidad de la e-interactividad con los pacientes y otros profesionales sanitarios

    Modeling and simulation of chloride diffusion in concrete with recycled aggregates

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    The concrete along with steel, are the responsibility structural material required to respond to mechanical stresses; specifically, the tensile stresses are borne by the steel, and it is this material that involvement of durability can lose their resilience. Corrosion of steel is one of the main causes of this affectation in the steel, and this is caused by the entry of chloride ions in the called phenomenon diffusion. This phenomenon is governed by the diffusion equations of the Fick's first and second law [1]; for these, there are several models that describe the behavior of chloride diffusion in conventional concrete, but nevertheless, not in the recycled concrete. In this paper, are used as basis, the models of Janzhuang Xiao et al. [2] and Long-Yuang Li et al. [3] to model and simulate the phenomenon of chloride diffusion in concrete with recycled aggregates; for which it has been used a five-phase model for the aggregate: old and new Interfacial Transition Zones (ITZ), new and old mortar, and original aggregate. Furthermore, in this model were considered as variables the Thickness of the Interfacial Transition Zone (TITZ), the rate of old mortar adhered, the volume fraction of the aggregates and the continuity of the ITZ. The model considered, was composed by aPeer ReviewedPostprint (published version
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