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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
Survival, habitat use and disturbance behaviour of re-introduced grey partridges "Perdix perdix" L. in an enhanced arable landscape in the Swiss Klettgau
Get PDFIn the last forty years, the Swiss lowlands have lost much of their former value as habitat for
wild plants and animals, mainly because of the effects of modern farming practices. One of
the most prominent and charismatic species affected is the Grey Partridge Perdix perdix L.
Considering the alarming decline of the Grey Partridge, the Swiss Agency for the
Environment, Forests and Landscape (SAEFL) entrusted the Swiss Ornithological Institute in
1991 to undertake a ten year project on “Protection measures for brown hare and Grey
Partridge” (Jenny et al. 2002). In this context the “Klettgau” in the canton of Schaffhausen
was chosen as study area as it was one of the two regions in Switzerland where wild
partridges still remained in small numbers at that time. To reverse the main cause of the
partridge’s decline - habitat loss - the main activity in the early stages of the project was the
promotion of ecologically enhanced habitats such as wild-flower strips and hedges.
Unfortunately, the already very small partridge population went extinct shortly after the
beginning of the project. However, by 1998 the area of partridge-friendly habitats had grown
to such an extent that it allowed to launch a partridge re-introduction project. This was
undertaken as part of the Swiss Ornithological Institute’s project “Birds as test organisms to
evaluate enhanced habitat diversity in agricultural areas” which was launched in 1996.
The main aims of this thesis for which the data was collected between 1998 and 2001 are to
assess whether Grey Partridges:
1) are able to survive and reproduce in an ecologically enhanced landscape such as the
Klettgau,
2) make use of the enhanced areas and, if so, which value they have for them,
3) are disturbed by human and predator activities within the re-introduction area,
4) to conclude if and under what conditions further partridge re-introductions in Switzerland
might be successful.
Study area
The study area (c. 530 ha) is intensively cultivated, mainly for growing cereals (49%), oilseed
rape and sunflowers (14%) and root crops (12%). Grassland covered 11%, another 11%
were bare of vegetation (buildings, roads, etc). Permanent cover such as wild-flower strips,
hedgerows and grass banks amounted to 3% of the area. Field sizes ranged from 0.1 to 5.5 ha.
From 1991 to 2001 the area of wild-flower strips increased from 0 ha to 12 ha, the area of
hedgerows from 2 ha to 2.7 ha. Besides agricultural use, the study area is very popular for
recreation mainly by walkers with or without dogs and riders. In the centre of the study site
there is a dog training school and an arena to school horses, in the northern part of the area
there is a cycling route.
Origin of birds released
Originally it was planned to release wild translocated birds of the western clade of the
subspecies Perdix perdix perdix only (50 per year) as it is widely accepted that this technique
generates the highest possible re-introduction success in areas where the species has become
extinct. After the first year of this study however, it became apparent that it was impossible to
organize enough wild-caught birds for release (n = 21 released in total). I therefore had to
switch to the next most promising option which I considered to be parent-reared birds
released as coveys in autumn (n = 77). In the second and third year of this study we
additionally fostered parent-reared chicks to already re-established adult birds which had
failed to produce their own young (n = 32).
Dispersal, survival and causes of death
Of the 98 released adult partridges, 73% remained within the study area and 52% survived the
first month after release. During the first month after release, they frequently moved across
the whole research area. After settling, 98% of all partridge locations were recorded in that
part of the study area where the density of enhanced areas was maximal.
Survival was highest in wild-hatched partridges of the founder population (mean ± SE;
0.90 ± 0.03), followed by that of fostered chicks (0.86 ± 0.03) and translocated adult wild
birds (0.82 ± 0.06). While survival of these groups was not statistically different from each
other, survival of captive-reared adults was significantly lower (0.70 ± 0.06). We found the
carcasses of 91 partridges. 88 of them were predated, 1 died because of disease, 1 because of
a traffic accident and 1 as a result of a territorial fight. Predation by mammals (mainly foxes)
was twice as frequent as predation by avian predators.
Reproductive success
We observed 19 pairs that started egg laying. Of those, seven broods hatched and twelve
failed. Mean clutch size of first clutches was 15.6 eggs (N = 9 clutches, SD = 1.3). Only one
second clutch was found. 86% of all eggs hatched (N = 7 broods). The average percentage of
successful nests over three years was only 0.33 [SE = 0.08]. When breeding the year after
release, fostered chicks tended to have more successful nests (0.44 [SE = 0.43]) than when
individuals of the other treatment groups were involved (reared adults: 0.17 [SE = 0.03];
translocated: 0.25 [SE = 0.07]; wild hatched in study area: 0.27 [SE = 0.29]), but the
differences were not statistically significant. Eleven out of 19 nest were located in wild-flower
strips.
Habitat use and home range size
At the level of the individual family group (pairs or coveys), we found a significantly greater
use (throughout the year) of habitat areas that were enhanced with wild-flower strips and/or
hedges, compared to non-enhanced areas. When the birds used the agricultural fields,
densities of use declined sharply with increasing distance from the nearest enhanced area.
Thus, the availability and spatial distribution of ecologically enhanced areas were the main
determinants of the partridges’ range use. Despite their strongly over-proportional use of
enhanced areas, the partridges spent a large proportion of time in cultivated fields. In summer,
frequently visited vegetation types were cereals (average 26.1% of locations), root crops
(14.8%) and grassland (9.3%). In winter, the birds spent much of their activity in cereals or
stubble fields (32.7%) and rape (24.1%). This indicates that these types of vegetation,
particularly cereals, were attractive resources, although not preferred in respect to their
availability.
The size of the group home-ranges varied significantly with season. In spring (prebreeding
period) and summer (breeding period), the average home-ranges ( ± SD) were 6.8
( ± 4.0) ha and 6.9 ( ± 2.6) ha, respectively. From late summer until the end of winter (nonbreeding
period), the home-ranges were significantly larger; late summer: 15.2 ( ± 6.6) ha;
autumn: 17.0 ( ± 4.0) ha; winter: 14.4 ( ± 3.6) ha.
Disturbance
Partridges showed a distinctive cause-specific reaction repertoire to all disturbance types
compared, mainly crouching in presence of raptors and showing vigilance in presence of
mammals (foxes and cats). Flushing was the main reaction when disturbed by leisure
activities. When flushed, partridges reduced their flight distance by 54 metres compared to
unforced flights and remained in their territory in 87% of all cases. In summer, their main
escape cover was cultivated fields, whereas in winter they mainly used permanent cover such
as wild-flower strips and hedges. The spatial distribution of partridges was influenced by
season: In summer, partridges avoided areas with high human disturbance, whereas in winter
they avoided areas with high predator abundance and close proximity to tall hedges. Human
activities caused twice as much disturbance events as predators, with associated energetic
costs. Overall, disturbance substantially limited overall spatial use, with consequences for the
carrying capacity of the area.
Conclusion
This study shows that with enough staying power even the intensively exploited Swiss
countryside may provide a satisfactory environment for a highly demanding species such as
the Grey Partridge. Even though it is not possible to prove from this study’s results if further
partridge re-introductions in Switzerland or abroad will be successful in terms of creating
self-sustainable populations – for that the duration of the study was simply too short - it is
possible to draw four basic conclusions for future partridge re-introduction projects:
1) Prior to every partridge re-introduction or re-establishment the habitat must be enhanced
with permanent habitat structures such as hedgerows and wild-flower strips.
2) If translocated wild birds are not available for release, chicks should be fostered whenever
possible, in the best case to wild birds still resident in the area.
3) Re-introductions should only be envisaged in areas with low predator numbers and human
activities.
4) In order to find possible weaknesses in re-introduction projects, post-release monitoring is
essential to ensure the project targets are met
The relative importance and biological significance of non-stop and intermittent flight strategies in bird migrants crossing the Sahara
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The aim of this thesis was to investigate the flight and resting strategies of birds crossing the Sahara on migration. In order to overcome the severe limitations of ground observations, we chose radar to obtain continuous data of the temporal and spatial distribution of bird migration and to answer the core question whether migrants cross the largest desert by a long non-stop flight or rather by intermittent flying and resting. Study site and methods The Swiss Ornithological Institute carried out extensive radar and field studies at three different study sites in Mauritania, covering three migration seasons in 2003 and 2004. One station (20°56’ N; 11°35’ W), close to the oasis Ouadâne and about 500 km east of the Atlantic coast, was run permanently for about two moths in spring and autumn 2003 and in spring 2004. It provided continuous data on the course of bird migration across this part of the Sahara. The two other radar sites were operated about 300 km further to the East in the plain sand desert close to the border of Mali. At Mohammed Lemna (18°35’ N; 08°38’ W) radar data was collected for eleven days in September 2003. At Bîr Amrâne (22°47’ N; 08°43’ W), located about 450 km further to the North of Mohammed Lemna, the observations covered about three weeks in April 2004 (chapter I). Quantification of bird migration by means of radar is still a difficult task, in spite of almost sixty years of growing experience in radar ornithology. We present for the first time a method how radar data can be analysed to achieve reliable estimates of the number of migrating birds in a given air space. To reach this goal three basic steps of quantification must be considered: (1) echo detection, (2) echo identification and (3) quantification. First, the radar must be calibrated to allow the calculation of standardized echo sizes that are independent of distance. Then a distance-dependent threshold to reduce the detection of small targets at close range has to be applied. After this basic step, the remaining echoes must be assigned to bird or insect targets, eventually eliminating the insects. In our case, we were also able to determine the birds’ body axis relative to the radar (aspect) and to differentiate detection probabilities according to echo sizes. For the final quantification, we estimated the surveyed air space with respect to the specific detection range per echo size class. Using this method we calculated the temporal and spatial distribution of bird migration crossing the western Sahara (chapter II). Composition of daytime migration Billions of songbirds breeding in the western Palaearctic cross the Sahara desert twice a year. While crossing temperate latitudes most of them use an intermittent flight strategy, i.e. fly at night and rest or feed during the day. As resting and feeding in the Sahara is much less rewarding than in Europe, we investigated whether in the Sahara migration during daytime comprises the normal diurnal migrant species or the nocturnal ones prolonging their flight into the day. At the radar station Ouadâne, spring passage of passerine migrants showed high variation from night to night, but in general passerine densities decreased towards sunrise. However, under favourable wind conditions passerine migration continued far into the day, mostly at high altitudes (around 2000 m above ground level). These relatively high densities of passerines flying during the day were in contrast to very low proportions of real diurnal migrants detected on daily transect counts in the study area. For nocturnal migrants, however, the transect counts showed high correlation IX-
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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