1,721,221 research outputs found
Sistemas radicales de cultivos: extensión, distribución y crecimiento
Full text linkThe roots are the plant organs responsible for water and nutrient absorption which are needed for adequate plant growth. Therefore, it is important to know both the extent and distribution of the root system into the soil since it determines the ability of the plant for mining soil resources, especially in poor soils or soils with low nutrient or water availability. The present work describes the root system of different crops and their relationships with the shoot, and how it determines the efficiency for nutrient uptake. On the other side, we review some morphological adaptations of the root system that improve the absorption of nutrients. This work also describes how the renewal of the root system occurs in a growing season and how it changes or adapts depending on environmental stress factors affecting the plants.Las raíces son los órganos encargados de la absorción de nutrientes y agua que son necesarios para el correcto desarrollo de las plantas. Por lo tanto, es importante conocer tanto la extensión como la distribución de las raíces en el suelo, ya que determinan la cantidad de recursos que pueden ser aprovechados por los cultivos, especialmente en situaciones de baja disponibilidad. El presente trabajo describe el tamaño radical de diversos cultivos y su relación con la parte aérea y cómo este determina la eficiencia de absorción de nutrientes. Por otro lado, se revisaron algunas adaptaciones morfológicas del sistema radical que otorgan ventajas a las plantas para absorber nutrientes. También describe la renovación del sistema radical en la estación de crecimiento del cultivo y cómo cambia o se adapta, dependiendo de factores ambientales que estresan a las plantas
Response to Nelson et al.: ventral parietal subdivisions are not incompatible with an overarching function.
No full texthttp://www.sciencedirect.com/science/article/pii/S136466131200153
Cognitive contributions of the ventral parietal cortex: an integrative theoretical account.
No full textAlthough ventral parietal cortex (VPC) activations can be found in a variety of cognitive domains, these activations have been typically attributed to cognitive operations specific to each domain. In this article, we propose a hypothesis that can account for VPC activations across all the cognitive domains reviewed. We first review VPC activations in the domains of perceptual and motor reorienting, episodic memory retrieval, language and number processing, theory of mind, and episodic memory encoding. Then, we consider the localization of VPC activations across domains and conclude that they are largely overlapping with some differences around the edges. Finally, we assess how well four different hypotheses of VPC function can explain findings in various domains and conclude that a bottom-up attention hypothesis provides the most complete and parsimonious account
Chiral Pesticides with Asymmetric Sulfur: Extraction, Separation, and Determination in Different Environmental Matrices
Full text linkChiral pesticides with S atoms as asymmetric centers are gaining great importance in the search for new pesticides with new modes of action. As for the rest of the chiral pesticides, the determination of the stereoisomers separately has become crucial in the environmental risks assessment of these pesticides. Therefore, the development of suitable extraction and clean-up methods as well as efficient stereoselective analytical techniques for stereoisomers determination in environmental samples is essential. Currently, liquid/solid phase extraction, microextraction, and QuEChERS-based methods are most commonly used to obtain chiral pesticides from environmental samples. Gas, liquid, and supercritical fluid chromatography together with capillary electrophoresis techniques are the most important for the determination of the stereoisomers of chiral pesticides containing S atoms in its structure. In this study, all these techniques are briefly reviewed, and the advantages and disadvantages of each are discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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