1,948 research outputs found
Influence of Dosages of Biofertilizers Composed of Mycorrhizae and Diazotrophs on the Corn Productivity
Corn (Zea mays L.) is a crop of world importance, however, one of the problems present during its development is the lack of nutrients or the presence of these in a form not available to the plant. Because of this, the objective of this review article is to gather information on the influence of different dosages of mycorrhiza and diazotroph biofertilizers on the corn crop. A meticulous bibliographic research was carried out, detailing the methods used by various authors; Among the most repetitive and significant factors are the use of mycorrhizae and nitrogen-fixing bacteria plus fertilization with P, the following treatment stands out: 200 gr ha−1 (using mycorrhizae and nitrogen-fixing bacteria); the common response variable of the authors mentioned in methodology was grain yield. The results obtained by the majority of authors show that grain yield improves significantly in the interaction of mycorrhizae and diazotrophs plus chemical fertilization; As a result of the aforementioned treatment, the yield of corn kg ha−1 was increased by 37%, by virtue of these results it is concluded that the most appropriate thing would be to take it into account to apply it on the corn crop.
Keywords: Inoculants, Nitrogen Fixing Bacteria, Symbiotic Fungi.
Resumen
El maíz (Zea mays L.) es un cultivo de importancia mundial, sin embargo, uno de los problemas presentes durante su desarrollo, es la falta de nutrientes o la presencia de estos en forma no disponible para la planta. Debido a esto, el objetivo de este artículo de revisión es recopilar información sobre la influencia de las diferentes dosificaciones de biofertilizantes a base de micorriza y diazótrofos sobre el cultivo de maíz. Se realizó una minuciosa investigación bibliográfica, detallando métodos utilizados por varios autores; entre los factores más reiterativos y significativos están el empleo de micorrizas y bacterias fijadoras de nitrógeno más la fertilización con P, sobresaliendo el siguiente tratamiento: 200 gr ha−1 (usando micorrizas y bacterias fijadoras de nitrógeno); la variable respuesta en común de los autores mencionados en metodología fue el rendimiento del grano. Los resultados obtenidos por la mayoría de autores muestran que el rendimiento del grano mejora significativamente en la interacción de micorrizas y diazótrofos más la fertilización química; producto del tratamiento mencionado anteriormente, se aumentó un 37% el rendimiento del maíz kg ha−1, en virtud a estos resultados se concluye que lo más adecuado sería tomar en cuenta para aplicarla sobre el cultivo de maíz.
Palabras Clave: Inoculantes, bacterias fijadoras de nitrógeno, hongos simbiontes
Middle Palaeolithic flint procurement in Central Mediterranean Iberia: IMplications for human mobility.
Different flint types from the Middle Palaeolithic site of Abrigo de la Quebrada (Chelva, Valencia) are characterized, both macro- and microscopically, and compared with types found at other localities in the region. Although procurement predominantly concerned the immediate vicinity of sites, our results show the presence of the same types in assemblages separated by distances of up to 120 km. The long distances involved are suggestive of a pattern of North-South mobility of human groups along the coastline of central Mediterranean Iberia
Finite-dimensional Nichols algebras over dual Radford algebras
For n, m ∈ N, let Hn,m be the dual of the Radford algebra of dimension n 2m. We present new finite-dimensional Nichols algebras arising from the study of simple Yetter-Drinfeld modules over Hn,m. Along the way, we describe the simple objects in Hn,m Hn,m YD and their projective envelopes. Then, we determine those simple modules that give rise to finite-dimensional Nichols algebras for the case n = 2. There are 18 possible cases. We present by generators and relations the corresponding Nichols algebras on five of these eighteen cases. As an application, we characterize finite-dimensional Nichols algebras over indecomposable modules for n = 2 = m and n = 2, m = 3, which recovers some results of the second and third author in the former case, and of Xiong in the latter.Fil: Bagio, D.. Universidade Federal de Santa Maria; BrasilFil: García, Gastón Andrés. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matemáticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Jury Giraldi, Joao Matheus. Universidade Federal de Santa Maria; BrasilFil: Márquez, O.. Universidade Federal de Santa Maria; Brasi
Validação da escala breve do comportamento resiliente (BRCS) uma amostra multiétnica de idosos chilenos
[EN] The aim of this study was to analyze the psychometric properties of the Brief Resilient Coping Scale (BRCS) for a multiethnic sample of Chilean older people (800). This sample has the particular feature of including non-indigenous (231) and indigenous Aymara (201) and Mapuche (368) people resident in native rural areas. It is a cross-sectional study. Descriptive statistics were calculated for socio-demographic and outcome data, covering mean, standard deviation, frequencies and percentages. For the BRCS, psychometric properties were analyzed according to the principles of Classical Test Theory. The analysis of the psychometric properties of the BRCS for three ethnic groups of older Chilean people shows that this rating scale is acceptable, reliable and valid, although the differences between groups highlight the need for culturally adapted geriatric assessment scales. The BRCS showed satisfactory psychometric characteristics for the studied samples. It is important for medical and social sciences to have ethnically sensitive instruments for the evaluation of psychosocial resources that promote successful aging. [ES] El objetivo de este estudio fue analizar las propiedades psicométricas de la Escala Breve de Afrontamiento Resiliente (BRCS) para una muestra multiétnica de 800 personas mayores chilenas. Esta muestra tiene la particularidad de incluir personas no indígenas (231) e indígenas aymaras (201) y mapuche (368) residentes en áreas rurales nativas. Se llevó a cabo un estudio transversal. Se realizaron análisis descriptivos para las variables sociodemográficos, tales como media, desviación estándar (DE), frecuencias y porcentajes. Para BRCS, las propiedades psicométricas se analizaron de acuerdo con los principios de la Teoría Clásica de las Pruebas. Los análisis de las propiedades psicométricas de BRCS para los tres grupos étnicos de personas mayores chilenas muestran que esta escala es aceptable, confiable y válida, aunque las diferencias entre los grupos resaltan la necesidad de que las escalas de evaluación geriátrica sean adaptadas culturalmente. BRCS mostró características psicométricas satisfactorias para las muestras estudiadas. Es importante para las ciencias médicas y sociales contar con instrumentos étnicamente sensibles para la evaluación de los recursos psicosociales que promueven un envejecimiento exitoso. [PT] O objetivo deste estudo foi analisar as propriedades psicométricas da Escala Breve do Comportamento Resiliente (BRCS) para uma amostra multiétnica de 800 idosos chilenos. Esta amostra tem a particularidade de incluir pessoas não indígenas (231), Aimarás (201) e Mapuche (368) residentes em áreas rurais nativas. Foi realizado um estudo transversal. Foram realizadas análises descritivas para as variáveis sociodemográficas, como média, desvio padrão (DP), frequências e percentuais. Para a BRCS, as propriedades psicométricas foram analisadas segundo os princípios da Teoria Clássica dos Testes. As análises das propriedades psicométricas da BRCS para os três grupos étnicos de idosos chilenos mostram que esta escala é aceitável, confiável e válida, embora as diferenças entre os grupos destacam a necessidade de adaptação cultural das escalas de avaliação geriátrica. BRCS mostrou características psicométricas satisfatórias para as amostras estudadas. É importante para as ciências médicas e sociais contar com instrumentos etnicamente sensíveis para a avaliação dos recursos psicossociais que promovem o envelhecimento bem- -sucedido.This work was supported by the Government of Chile (Proyecto FONDECYT 1170493) and University of Tarapacá (Proyecto UTA MAYOR 3768-20) and the Research Program of the Madrid Autonomous Community, Spain (ENCAGENCN, Ref: H2019/HUM-5698).S
Junction conditions of Palatini f (R,T) gravity
We work out the junction conditions for the Palatini f(R, T) extension of general relativity, where f is an arbitrary function of the curvature scalar R of an independent connection, and of the trace T of the stress -energy tensor of the matter fields. We find such conditions on the allowed discontinuities of several geometrical and matter quantities, some of which depart from their metric counterparts, and in turn extend their Palatini f(R) versions via some new T-dependent terms. Moreover, we also identify some "exceptional cases " of f(R,T) Lagrangians such that some of these conditions can be discarded, thus allowing for further discontinuities in R and T and, in contrast with other theories of gravity, they are shown to not give rise to extra components in the matter sector, e.g., momentum fluxes and double gravitational layers. We discuss how these junction conditions, together with the nonconservation of the stress-energy tensor ascribed to these theories, may induce nontrivial changes in the shape of specific applications such as traversable thin-shell wormholes
Mechanical and Durability Properties of Concrete with Coarse Recycled Aggregate Produced with Electric Arc Furnace Slag Concrete
ABSTRACT: The search for more sustainable construction materials, capable of complying with quality standards and current innovation policies, aimed at saving natural resources and reducing global pollution, is one of the greatest present societal challenges. In this study, an innovative recycled aggregate concrete (RAC) is designed and produced based on the use of a coarse recycled aggregate (CRA) crushing concrete with electric arc furnace slags as aggregate. These slags are a by-product of the steelmaking industry and their use, which avoids the use of natural aggregates, is a new trend in concrete and pavement technology. This paper has investigated the effects of incorporating this type of CRA in concrete at several replacement levels (0%, 20%, 50% and 100% by volume), by means of the physical, mechanical and durability characterization of the mixes. The analysis of the results has allowed the benefits and disadvantages of these new CRAs to be established, by comparing them with those of a natural aggregate concrete (NAC) mix (with 0% CRA incorporation) and with the data available in the literature for concrete made with more common CRA based on construction and demolition waste (CDW). Compared to NAC, similar compressive strength and tensile strength values for all replacement ratios have been obtained. The modulus of elasticity, the resistance to chloride penetration and the resistance to carbonation are less affected by these CRA than when CRA from CDW waste is used. Slight increases in bulk density over 7% were observed for total replacement. Overall, functionally good mechanical and durability properties have been obtained.Funding: This research was co-financed by the European Regional Development Fund (ERDF) and the Ministry
of Economy, Industry and Competitiveness (MINECO) within the framework of the project RTC-2016-5637-3 and in collaboration with the company INGECID and the department LADICIM (University of Cantabria)
Incidence of multiple sclerosis among European Economic Area populations, 1985-2009: the framework for monitoring
Background:
A debate surrounding multiple sclerosis epidemiology has centred on time-related incidence increases and the need of monitoring. The purpose of this study is to reassess multiple sclerosis incidence in the European Economic Area.
Methods:
We conducted a systematic review of literature from 1965 onwards and integrated elements of original
research, including requested or completed data by surveys authors and specific analyses.
Results:
The review of 5323 documents yielded ten studies for age- and sex-specific analyses, and 21 studies for
time-trend analysis of single data sets. After 1985, the incidence of multiple sclerosis ranged from 1.12 to 6.96 per 100,000 population, was higher in females, tripled with latitude, and doubled with study midpoint year. The north registered increasing trends from the 1960s and 1970s, with a historic drop in the Faroe Islands, and fairly stable data in the period 1980-2000; incidence rose in Italian and French populations in the period 1970-2000, in Evros (Greece) in the 1980s, and in the French West Indies in around 2000.
Conclusions:
We conclude that the increase in multiple sclerosis incidence is only apparent, and that it is not
specific to women. Monitoring of multiple sclerosis incidence might be appropriate for the European
Economic AreaS
In glacial environments beyond glacial terrains: Human eco-dynamics in late Pleistocene Mediterranean Iberia
The Iberian Peninsula south of the Ebro River enjoyed one of the mildest climates of Pleistocene Europe, but still experienced significant and rapid environmental shifts caused by global climate regimes. We examine the interplay between technological, social, and land-use dynamics as culturally mediated responses to climate change outside the periglacial zone. We combine information from excavated sites across eastern and southeastern Spain with systematic survey data from an intensive study area within this larger region to examine Upper Paleolithic behavioral adaptations to the environmental shifts of the late Pleistocene (late MIS-3 through MIS-2). We define indexes that serve as proxies for land-use strategies, technological specialization, and hunting practices. Variation in these indices across space and through time provides the basis for a model of Upper Paleolithic eco-dynamics. A consistent pattern of land-use, involving inland (and possibly coastal) base-camps and near-coastal hunting zones spanned the Mediterranean facade and was sufficiently flexible and resilient to environmental change to persist throughout the late Pleistocene
El cambio del profesorado de ciencias II : itinerarios de progresión y obstáculos en estudiantes de magisterio
En este trabajo, segundo de una serie de dos, se presenta el progreso y los obstáculos que experimentan cinco equipos de estudiantes de Magisterio al participar en asignaturas basadas en el modelo Formación de Profesores para Investigar la Práctica (FOPIP), de orientación constructivista, y en el curso CAIC (Concepciones de los Alumnos e Innovación Curricular). Las categorías analizadas fueron: ideas de los alumnos, contenidos escolares y metodología de enseñanza de las ciencias. Para el análisis se formularon tres niveles de progresión, que fueron reformulados y ampliados a la luz de los datos, dando lugar a Itinerarios Generales de Progresión. Los resultados sugieren dos obstáculos de fondo: las ideas de los alumnos no tienen valor epistémico y el conocimiento científico representa verdades absolutas. Los equipos dieron pruebas de haber superado el primero pero no el segundo.This paper, the second in a series of two, presents the progress and obstacles experienced by five teams of prospective primary education teachers who participated in courses based on the constructivist-oriented model «Teacher Education for Inquiry into Practice (FOPIP)», and in the «Students' Conceptions and Curricular Innovation (CAIC)» course. The categories analyzed were: the students' ideas, school science content, and the methodology of Science Teaching. For the analysis, three levels of progression were proposed and then reformulated and expanded in the light of the data, resulting in General Itineraries of Progression. The results were suggestive of two substantive obstacles: the students' ideas have no epistemological value, and scientific knowledge represents absolute truths. There was evidence that the teams had surpassed the first obstacle, but not the second
Distribución de planta para mejorar la productividad, sub-área de habilitado y producción. Empresa Epin S.A.C. Chimbote, 2018
El presente desarrollo de tesis muestra una mejora en la productividad final a las principales
deficiencias de distribución de los puestos de trabajo, equipos y máquinas en una empresa
dedicada al rubro metalmecánico, aplicándose distintos métodos y herramientas de
ingeniería industrial, con la finalidad de identificar la situación actual y proponer distintas
opciones que permitan conseguir la solución óptima; por lo tanto el obj etivo principal de
esta tesis es implementar la óptima distribución de planta con el método SLP (Planificación
sistemática de distribución en planta) para mejorar la productividad en el sub-área de
habilitado y producción de la empresa EPIN S.A.C. Los métodos y herramientas que se
utilizaron para el desarrollo fueron el método SLP con sus respectivos diagramas, método
Güerchet, diagrama Pareto, causa y efecto, distancias recorridas, análisis P-Q, relación de
flujo y actividades, instrumento de validación de la investigación, y software CORELAP que
permitieron realizar una correcta recolección de datos respectivamente en cada una de las
etapas del desarrollo, obteniendo como resultado la productividad pre-test 0,1334 unidades
de producto sobre la hora hombre para la mano de obra; 0,0011 unidades de producto sobre
el costo en soles para la materia prima; 0,2999 unidades de producto sobre la hora máquina;
y productividad post-test 0,1578 unidades de producto sobre la hora hombre para la mano
de obra; 0,0011 unidades de producto sobre el costo en soles para la materia prima y 0,2531
unidades de producto sobre la hora máquina.
Se concluye que se logró un incremento porcentual del índice de productividad en 18,64%
de mano de obra; 18,50% en maquinaría y en la productividad materia prima, mantiene el
índice de productividad. Finalmente se confirma que con la aplicación del método SLP se
mejoró la productividad; consiguiendo a su vez el 85% de fiabilidad sobre el instrumento
aplicado
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