1,721,462 research outputs found
Do Acacia and Tamarix trees compete for water in the Negev desert?
No full textWe investigated the spatial distribution of the three Acacia and two Tamarix tree species and related the spatial distribution of these two genera to their 18O value, i.e. their 18O/16O isotopic ratio in the Negev desert, Israel. At the regional spatial scale, there was a significant difference in the overall distributions of these two genera, although there was considerable overlap. At the 1 km2 scale, there was no deviation from homogeneity. At a finer scale, no deviation from a random distribution was found in three ephemeral rivers between the two largest trees in these two genera, Acacia raddiana and Tamarix nilotica. We found that Tamarix used deep water from aquifers while Acacia trees used an alternate source, most likely surface water. Spatial segregation of Tamarix and Acacia occurs at the large spatial scale but not at the small scale, perhaps because of the high tolerance of Tamarix species for salinity and the low tolerance of Acacia species for saline conditions. It appears that the trees are not spatially segregated on the small scale because they use different water sources
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
Bone mineralization at the callotasis site after completion of lengthening.
No full textWe studied the course of bone mineralization of regenerate bone after callotasis lengthening. Twenty-three patients (eight boys) (mean age at operation 11.5 years, range 4-17 years; leg length discrepancy [LLD] at surgery ranging from 4 to 13 cm) underwent dual-energy X-ray absorptiometry (DEXA) scanning weekly during the distraction phase, at 2 week intervals until removal of the fixator, and at the time of their out-patient visits thereafter, for a mean of 794 +/- 420 days after removal of the apparatus. At removal of the fixator, the bone mineral content (BMC) of the regenerate was nearly 70% of the normal contralateral limb. With time, this value gradually increased, and tended to reach normal values, with no significant difference between femur and tibia. With time, the BMC of the regenerate tends to return to the value of the normal contralateral limb. Probably, once the limb length discrepancy has been equalized, the mechanical stimuli imparted through weight-bearing to the lengthened limb are of the same magnitude bilaterally. In this instance, then, the newly formed bone, responding to these physical stimuli, would normalize its mineral content, confirming that bone remodeling continues well after lengthening is terminated. Mineralization of the regenerate after completion of the lengthening process reaches values significantly greater than at removal of the fixator, with an increase of >50% of the prelengthening values, regardless of the underlying pathology. The final value of this increased BMC is not significantly different than in the normal contralateral unoperated limb. At least part of the increase in bone mineralization following callotasis lengthening is due to the normal process of growth and development
Bone mineralization gradient at the callotasis site.
No full textThirteen patients (18 lengthenings; mean age at operation, 11.0 years) underwent dual-energy X-ray absorptiometry (DEXA) scanning weekly during the distraction phase, at 2-week intervals until removal of the fixator, and at the time of each outpatient visit after removal of the apparatus for a median of 353 days. The three transverse regions remained significantly different in the 7 achondroplastic patients throughout the study, but the difference among these regions became nonsignificant by fixator removal in the 11 limb length discrepancy (LLD) patients. The most proximal region was significantly more mineralized throughout the study in the achondroplastic patients. The central region became the region of highest mineralization in the LLD patients by week 16 after removal of the fixator. The three longitudinal regions showed significantly different mineralization at all time points except at fixator removal. The central and medial regions always showed the highest mineralization. The mechanical characteristics of the fixator and the biomechanical features of the lengthening site may account for the mineralization gradient reported in this study and should probably be taken into account when planning removal of the fixator and subsequent weight-bearing
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
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