1,720,960 research outputs found
Modeling olive orchard response to water stress and definition of critical thresholds of soil water status.
No full textThe knowledge of the plant response to water stress is very important to predict the dynamic of potential
transpiration reduction under limited soil water condition. The water stress response is influenced by soil, plant
and climate and in particular by soil matric potential, hydraulic conductivity, osmotic head (in saline ecosystem)
and evapotranspirative atmospheric demand, as well as by root spatial distribution and plant properties.
The macroscopic approach, taking into account global stress indicator (relative transpiration, xylematic water
potential, etc), can allow to assess empirical functions, able to describe the plant response to water stress, on the
basis of the observed plant response to soil water status. Using the macroscopic approach it is not necessary to
evaluate separately difficult and time consuming soil and plant parameters, like the gradient of water potential at
the interface between the roots surface and the soil.
Modelling the plant response under water stress condition is crucial to identify the exact irrigation timing. In order
to assess the water stress functions, is necessary to estimate critical thresholds of soil water status, below which
plant transpiration starts to strongly decrease.
The main objective of the work is to investigate the relationships between soil matric potential and measured
transpiration, as well as to define the critical plant water status conditions, determined according to measured
leaf and stem xilematic potentials. Furthermore, the performance of existing models, simulating the relative
transpiration as a function of the soil matric potential, is assessed.
The soil water retention curve was used to determine, at the different depths, the soil matric potential according to
the measured of soil water contents obtained with capacitive sensors (Diviner 2000, Sentek).
Actual transpiration was monitored by measuring the sap flows with thermal dissipation probes (TDP), while the
leaf and stem water potentials were determined by using the Scholander pressure bomb.
The study area is located in the South-Western coast of Sicily (Italy); the dominant crop is represented by
table olive grove and it is characterized by typical Mediterranean semi-arid climate. According to the USDA
classification, the soil can be classified as silty clay loam. The investigation period included 2008 and 2009
irrigation seasons. Meteorological data were collected by means of a weather station of the SIAS (Servizio
Informativo Agrometeorologico Siciliano), located nearby the study area.
Experimental data allowed to define the critical threshold values of the soil water status (soil water content and
matric potential) below which the actual transpiration tends to reduce when soil water content decreases. For
values of soil water content greater than the critical threshold, the actual transpiration resulted almost constant. A
similar behaviour was observed when the xylematic potentials are used to quantify the crop water stress.
The investigation also showed that the best performance of the examined models, used to estimate transpiration,
can be obtained when non-linear models are considere
Modeling olive orchard response to water stress and definition of critical thresholds of soil water status
Get PDFThe knowledge of the plant response to water stress is very important to predict the dynamic of potential
transpiration reduction under limited soil water condition. The water stress response is influenced by soil, plant
and climate and in particular by soil matric potential, hydraulic conductivity, osmotic head (in saline ecosystem)
and evapotranspirative atmospheric demand, as well as by root spatial distribution and plant properties.
The macroscopic approach, taking into account global stress indicator (relative transpiration, xylematic water
potential, etc), can allow to assess empirical functions, able to describe the plant response to water stress, on the
basis of the observed plant response to soil water status. Using the macroscopic approach it is not necessary to
evaluate separately difficult and time consuming soil and plant parameters, like the gradient of water potential at
the interface between the roots surface and the soil.
Modelling the plant response under water stress condition is crucial to identify the exact irrigation timing. In order
to assess the water stress functions, is necessary to estimate critical thresholds of soil water status, below which
plant transpiration starts to strongly decrease.
The main objective of the work is to investigate the relationships between soil matric potential and measured
transpiration, as well as to define the critical plant water status conditions, determined according to measured
leaf and stem xilematic potentials. Furthermore, the performance of existing models, simulating the relative
transpiration as a function of the soil matric potential, is assessed.
The soil water retention curve was used to determine, at the different depths, the soil matric potential according to
the measured of soil water contents obtained with capacitive sensors (Diviner 2000, Sentek).
Actual transpiration was monitored by measuring the sap flows with thermal dissipation probes (TDP), while the
leaf and stem water potentials were determined by using the Scholander pressure bomb.
The study area is located in the South-Western coast of Sicily (Italy); the dominant crop is represented by
table olive grove and it is characterized by typical Mediterranean semi-arid climate. According to the USDA
classification, the soil can be classified as silty clay loam. The investigation period included 2008 and 2009
irrigation seasons. Meteorological data were collected by means of a weather station of the SIAS (Servizio
Informativo Agrometeorologico Siciliano), located nearby the study area.
Experimental data allowed to define the critical threshold values of the soil water status (soil water content and
matric potential) below which the actual transpiration tends to reduce when soil water content decreases. For
values of soil water content greater than the critical threshold, the actual transpiration resulted almost constant. A
similar behaviour was observed when the xylematic potentials are used to quantify the crop water stress.
The investigation also showed that the best performance of the examined models, used to estimate transpiration,
can be obtained when non-linear models are considered
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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