1,720,963 research outputs found
Potentiality of Non-homogeneous Hidden Markov Model (NHMM) as predictive tool of rainfall and temperature patterns in Everglades National Park under the Global Warming Scenarios
No full textClimate change poses a number of problems for the management and restoration of Everglades National Park and for the water supply systems in South Florida. Changes due to anthropogenic global warming in rainfall seasonality, intermittence and intensity together with variations of temperature and sea level (SL) may interact and determine the potential outcomes for surface and groundwater flows as well as other factors such as erosion, mangrove retreat, salinity and ecological diversity.
Due to the coarse spatial resolution of general circulation models (GCMs), and due to other factors, the statistics of precipitation at the local scale can be strongly biased in retrospective simulations. Many engineering models are designed to work with historical point precipitation data, and practitioners prefer to assess the performance of GCMs in the context of their models and the associated data inputs. Dynamical and statistical downscaling schemes are consequently employed. Here, a Non-Homogeneous Hidden Markov Model (NHMM) is applied for simulating future daily rainfall at nineteen stations in South Florida. The CMIP 5 simulation of the coupled ocean-atmosphere model CMCC-CMS from 1950-2100 is used for projection. The application directly considers seasonality through changes in the driving variables, rather than developing separate models for each canonical season. Biases between the re-analysis model and retrospective simulations of the CMCC-CMS are addressed. The results indicate that, as a consequence of increase of the CO2 concentration and temperature, South Florida may be subjected to drier conditions for most of the year. The number of wet days reduces while extreme rainfall frequency increases. These are consistent with trends of rainfall observed in the recent data. A modest reduction in total rainfall in the February to May period, and a slight increase in the September-October projected rainfall is noted. Changes in the expression of the North Atlantic Subtropical High in the model appear to correspond to circulation changes that determine the new seasonality and patterns of rainfall in the region
Homogeneous & non-homogeneous hidden markov downscaling model for projection of hydroclimate changes in Tanzania
No full textClimate change poses a number of problems to water resources. The precipitation change, expressed in amount of rainfall and occurrence of wet/dry days, could cause seasonal and annual shifts in the climatology of the area and bring up an extreme events intensification.
Therefore, the aim of the proposed work is to develop a Statistical Downscaling Methodology on the entire Tanzania territory, where water supply by superficial and underground sources play a key role. So, Any change in hydrologic cycle could constitute an hazard and adversely affect the sustainability and also the future economic development of the area.
A Hidden Markov Model (HMM) is here used to describe annual daily rainfall occurrence at 11 gauge stations in Tanzania, in east Africa, yearly along the period 1950-1990. The model assumes that rainfall occurrence is governed by a few discrete states, with Markovian daily transitions between them. Five ‘‘hidden’’ rainfall states are identified. These states are able to capture the typical Tanzanian seasonality conditions; and further the occurrence and amount of precipitations proper of the different stations.
Moreover, a Non-homogeneous Hidden Markov Model (NHMM) is then applied to downscale daily precipitation occurrence at the 11 stations, using daily large scale predictors extracted from the NCAR-NCEP reanalysis General Circulation Model (GCM) dataset as: Geo Potential Height (GPH), Temperature (T), Zonal and Meridional Winds (ZW & MW) and Vertical Equator Winds from 10 to 1000 hPa (ZEW).
The calibration (1950-1980) and validation (1981-1990) tests, for different predictor combinations, evidence that a considerably betterment in fitting the historical data is obtained by using the NHMM, which results able to simulate the seasonal rainfall pattern, characteristic of Tanzania. Then, the NHMM provides a useful diagnostic and predictive tool (a) in linking the statistics of daily rainfall occurrence and amount at the station level to the large-scale atmospheric patterns and (b) it can be used with the goal to make future projections of the downscaled precipitation by using the GCM’s simulations (CMIP5) under different global warming scenarios
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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