1,720,959 research outputs found
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
Developing a flood hazard analysis framework in the Cuvelai Basin, Namibia, using a flood model, remote sensing, and GIS.
Get PDFWorldwide, more than 40% of all natural hazards, and about half of all deaths, are the result
of flood disasters. In the Cuvelai River Basin (CRB), northern Namibia, flood disasters have
increased dramatically over the past half-century, along with associated economic losses and
fatalities. The increase in hydro-meteorological hazards such as floods are mainly attributed
to intense urbanisation, changing land-use patterns and a changing climate. These hazards are
exacerbated in semi-arid and data-sparse (SADS) regions such as the CBR, because of
declining and/or non-existent hydro-meteorological infrastructure. In addition there is a lack
of long-term continuous records that is needed to enhance the implementation of traditional
flood risk management strategies, whether structural or non-structural, to mitigate hydro-
meteorological hazards.
This thesis developed a systematic framework that has quantified the uncertainties associated
with the hydrological cycle that preclude the development of flood risk management
strategies. The framework is based on free-data and open-data and software that is available
online. It used remotely sensed data validated against ground-based observational data, where
available. The particular components of the hydrological cycle that are assessed are:
precipitation, surface runoff (discharge), surface water extent and surface water movement
pathways (drainage networks). Hydrologic modelling was used to model the water fluxes in
order to derive basin as well as flood characteristics of the study area. The framework can be
used as a benchmark for the development of flood risk management policies that will enable
SADS regions to mitigate the severe effect hydro-meteorological disasters in the
Anthropocene. The flood hazard analysis framework (FHAF) developed for this study
consists of two steps: (a) preliminary analysis and (b) hazard estimation. The preliminary
analysis enable the development of a hydro-meteorological (floods and droughts) archive
using different data sources as well as identifying where more analyses are needed to reduce
uncertainty while hazard estimation provide the frequency and magnitude of the hazard.
As a result of the growing concern about flood risk, identifying the extreme precipitation
events that cause hydro-meteorological disasters is essential. Hence, the preliminary analysis
step of FHAF developed a database (a). An up-to-date and broad analysis of the trends of
hydro-meteorological events within the CRB was performed. The derived events were also
validated against data from other sources.
The risk estimation step involved components of the hydrologic cycle that are crucial in
determining flood risk and that play an important role in enhancing uncertainty. Precipitation is one of these crucial components, to estimate and validate, especially in the trans-boundary
SADS CRB. Four commonly used operational satellite-based rainfall estimation (SBRE)
products were rigorously validated and inter-compared on monthly, seasonal, and annual
timescales. Rainfall data from gauged stations were compared against SBREs as well as
simulated data from a Regional Climate Model (RegCM4) model. Point-to-nearest-pixel and
pixel-to-pixel methods were used to validate gauge data against high spatial resolution (0.25o)
SBREs data for a period from 2008 to 2014. Validation was performed on a monthly,
seasonally, and annual basis as well as taking the long-term mean, whilst error statistics were
used to determine the accuracy of the SBREs when compared to the observed rainfall gauge
values. Results indicated good statistical relationships between the ground-based gauge
stations for some SBREs. Results will help to understand, and ultimately expand, our
understanding of the climatologies within this SADS region and will also provide valuable
information on the error structures of SBRE products that might be ingested into hydrologic
models for water resource management. The results also help to quantify the improvements
(bias correction) that are needed for these SBRE products to be useful for water resource and
risk management applications.
The second component, surface water pathways (drainage networks), is imperative to
determine flood inundation extent, which relate to hazards. Also, accurate delineation of
drainage networks is crucial for hydrological modelling and hydraulic modelling, and the
comprehension of fluvial processes. Channels from topographic maps (blue lines) were
compared to those from hydrologically corrected and uncorrected light detection and ranging
(LiDAR) DEMs (digital elevation models), heads-up digitised channels from high-resolution
digital aerial orthophotographs, field-mapped channels and auxiliary data. The maximum
gradient deterministic eight (D8) GIS algorithm was applied to the corrected and uncorrected
LiDAR DEMs using two network extraction methods: area threshold support and
curvature/drop analysis. Results will aid national mapping agencies in SADS regions to
modernise their national hydrography datasets and to account for changing land surface
conditions that can affect channel spatial arrangements over time.
The third component, deals with the amount, frequency, and magnitude of surface water
runoff (discharge). Sustainable management of water resources as well as mitigating hydro-
meteorological natural hazards such as flooding and drought requires the precise
understanding of the spatio-temporal distribution of water especially in SADS regions where
data from various global datasets are used to compensate. Results suggested that input data be ingested in hydrological models especially if the data are to be used especially for water
resources estimations and for understanding flood-producing processes.
The last component, surface water extent (flood inundation), was also estimated in this study.
The mapping of spatial inundation patterns during flood events is important for
environmental management and disaster monitoring. This study detected and compared the
spatial extent of flood inundation at the peak of three major flood events (2008, 2009, and
2011) in the CRB. The study follows a multi-spectral and multi-sensor approach to identify
the flood inundation for each flood event at peak modelled discharge. Results indicated that
the quantification of flooding spatial extent can help to provide valuable information to
FHAFs and hence potentially improve hydrologic prediction and flood management
strategies in ungauged catchments. Furthermore, given the globally availability of satellite-
based precipitation and river discharges, this proof-of-concept study can have substantial
implications on flood monitoring and forecasting in ungauged basins throughout the globe
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
Drought risk analysis using remote sensing and GIS in the Oshikoto region, Namibia.
No full textThesis (M.Env.Dev.) - University of KwaZulu-Natal, Pietermaritzburg, 2009.Drought is a recurrent climatic process that occurs with uneven temporal and spatial characteristics over broad areas and over an extended period of time. Therefore, detecting drought onsets and ends as well as assessing drought severity using satellite-derived information is essential. This should be especially the case in an arid country like Namibia where drought is part of Namibia’s climatology. It is believed that proper planning and research using near real-time data can curb the devastating environmental and socio-economic impacts of drought. Weather data used currently are often from a very sparse meteorological network, incomplete and/or not always available in good time to enable delineating accurately and timely, regional- and local-scale droughts. Consequently, the detection and monitoring efforts are hampered to provide timely and unbiased information to decision makers for accurate drought relief allocation and for land reform purposes. Furthermore, even though, data obtained from satellite-based sensors such as the Advanced Very High Resolution Radiometer (AVHRR) have been studied as a tool for drought monitoring for many years and provides an extensive temporal record for comparison, its coarse spatial resolution limits its effectiveness at detecting local scale variability where severe droughts might go undetected due to these data constraints. The objective of this study was to evaluate satellite-based and meteorological drought indices for the spatial and temporal detection, assessment and monitoring of drought condition to accurately delineate drought characteristics of drought prone areas. The study computed the Vegetation Condition Index (VCI) and Normalized Difference Vegetation Index (NDVI) from the 250m resolution NDVI data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor and one- and three-months Standardized Precipitation Index (SPI) data from rainfall stations in the study area. Detailed analyses of spatial and temporal drought dynamics during three seasons (2005/6 - wet, 2006/7 - normal and 2007/8 - dry) have been carried out through index maps generated in a Geographic Information Systems (GIS) environment from the mentioned data. Analysis and interpretation of these maps, which give different drought scenarios, reveal that remotely-sensed drought indices can accurately detect and map the local and regional drought spatial occurrence. Moreover, statistical analysis found strong correlations between the regional crop production data and the remotely-sensed data. However, the results showed that the local and regional drought occurrences detected were not reflected in national crop production data, confirming the suspicion that important local spatial variations are only detected if higher spatial resolution data are used. The study concluded that fine spatial resolution satellite data should be used to aid decision makers in monitoring and detecting drought which will also aid the allocation of millions of dollars in drought relief funds.http://hdl.handle.net/10413/53
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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