1,720,965 research outputs found
Assessment of genetic diversity in natural European hophornbeam (Ostrya carpinifolia Scop.) populations in Turkey
No full textGenetic diversity is a crucial component for plant survivability and fitness in terms of adaptation, genetic stability and variability. In this study, a total of 160 genotypes were investigated using 12 random amplified polymorphic DNA (RAPD) primers to understand the genetic structure and diversity of nine naturally distributed Ostrya carpinifolia populations in Turkey. Twelve RAPD primers yielded 111 clearly identifiable DNA bands, of which 71 bands were found to be polymorphic (64%). Observed number of alleles (Na), effective number of alleles (Ne) and Nei's gene diversity (h) were found as 2, 1.53 and 0.32, respectively. Total genetic variation (H-T), within-population genetic variation (H-S) and Nei's genetic differentiation coefficient (G(ST)) were found as 0.32, 0.09 and 0.70, respectively. Genetic diversity analysis (AMOVA) revealed highly significant (P < 0.001) genetic variations among and within populations. 69.94% of total variation was observed among populations while 26.69% was within populations. Gene flow value was calculated as 0.21 (Nm < 0.5), which could homogenize the genetic structure of a population. Two geographically isolated populations demonstrated high gene diversity and polymorphic loci ratio, indicating a relationship between geographic distribution of populations and eco-geographic factors. The findings of this study will pave the way for understanding the genetic diversity between inter- and intra-populations of O. carpinifolia species, as well as they would provide valuable information for management, conservation and utilization of in situ and ex situ Ostrya germplasms
Determination of Arsenic Amount in Some Trees that Can Be Used as Biomonitors
Get PDFToxic metals/metalloids such as arsenic are environmental pollutants that are damaging to living organisms. Commonly found metals pose a serious threat to human health unless they are controlled. In this study, the accumulation of As metalloid, which has entered the food chain for specific reasons, in plant organs was determined, and it was examined whether plants are hyperaccumulators against As concentration. As a result, Pinus pinaster Aiton., Cupressus arizonica Greene., Picea orientalis (L.) Peterm., Cedrus atlantica (Endl.), and Pseudotsuga menziesii (Mirb.) species accumulated more than 1 mg/kg As concentration. The highest average As concentration (7.91 mg/kg) was found in the northern bark of P. menziesii. The highest As concentrations in wood were found in the eastern direction for P. pinaster (5.21 mg/kg), C. arizonica (4.99 mg/kg), and P. orientalis (4.02 mg/kg), and in the western direction for C. atlantica (3.56 mg/kg) and P. menziesii (3.88 mg/kg). Additionally, it was determined that As concentration varied depending on location, direction, species, and year
Effect of Drought and UV-B Stress on Anatomical and Physiological Characters in Acer negundo and Acer pseudoplatanus Species
Get PDFClimate change is a situation that causes an increase in global temperature due to the increase in greenhouse gases in the atmosphere and the effect of natural processes. This temperature increase causes many environmental effects around the world. Two of these effects are ultraviolet-B (UV-B) radiation, a harmful type of electromagnetic light from the sun, and severe water shortages called droughts. In this study, we tried to determine how the wood structure (properties of libriform fibers and various mechanical properties) and plant photosynthesis parameters of Acer negundo and Acer pseudoplatanus species changes under two droughts (moderate and severe) and UV-B (low [8 kJ m-2 h-1] and high [12 kJ m-2 h-1]) stresses. Also, leaf gas exchange parameters (net photosynthesis, stomatal conductance, transpiration rate, and water use efficiency) were evaluated under these stressors. As a result, it was observed that fiber wall thickness decreased in seedlings exposed to both drought and UV-B radiation in both species. It was determined that plant gas exchange parameters decreased with drought stress but did not vary much with UV-B stress; the amount of plant transpiration decreased with the effect of drought and increased with the amount of UV-B radiation. The plant may have reduced transpiration to reduce the effect of drought stress and increased transpiration to use UV-B radiation for plant growth.YOK 100/2000 ScholarshipDuzce University Scientific Research Coordination Office [2021.02.02.1152]Thank YOK 100/2000 Scholarship and Duzce University Scientific Research Coordination Office (Project No: 2021.02.02.1152)
The effects of climate change scenarios on Tilia ssp. in Turkey
Get PDFGlobal climate change will cause significant changes in climate parameters, especially temperature increases and changes in precipitation regimes worldwide. Since the life of living things is directly related to climate parameters, this process will inevitably affect all living things. The plants will be the most affected living things from this process because they do not have an effective movement and migration mechanism. Therefore, global climate change will cause significant species and population losses in plants. To minimize the potential loss of species and populations, it is necessary to predetermine the potential changes in species' distribution areas and take necessary actions. Therefore, this study was aimed to determine the distribution areas of three Tilia species (Tilia tomentosa, Tilia cordata, and Tilia platyphyllos), which have economic, ecologic, and social value and show the local distribution in Turkey and to determine how they will be affected by global climate change. Within this scope, nineteen bioclimatic variables, Emberger climate classification, aspect, and topographic altitude variable were used in the modeling process. By modeling the scenarios SSP 245 and SSP 585, the projections were made for 2040, 2060, 2080, and 2100 regarding the areas suitable for the growth of these species and how these areas will change compared to their current situation. The results suggest that the distribution areas of all three Tilia species will change due to climate change, and the area of loss will be 43.5 km(2) (4%) for T. tomentosa, 9953.6 km(2) (15%) for T. platyphyllos, and 448.0 km(2) (19%) for T. cordata. Moreover, a more important point here is that increases and decreases will be observed in their distribution areas, and these changes will occur in a short process and at significant levels. In this case, the migration mechanism that these species will require must be provided by humans
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
Assessment of genetic variations of silver lime (Tilia tomentosa Moench.) by RAPD markers in urban and forest ecosystems
No full textIn the present study, the genetic diversity analysis of Tilia tomentosa plants was performed by using random amplified polymorphic DNA (RAPD) primers. Twenty eight plant samples, collected from urban (25 members) and forest (3 members) ecosystems, were used in this study. A total of 53 bands were obtained from eight RAPD primers, of which 48 (90.6%) were polymorphic. The percentage of polymorphic loci (P) was found to be 94.29%, the observed number of alleles (Na) was 1.94, the effective number of alleles (Ne) was 1.60, Nei's gene diversity (h) was 0.34 and Shannon's information index (I) was 0.50. Unweighted pair group method with arithmetic mean (UPGMA) cluster analysis revealed two major groups. Members of the urban and forest ecosystems showed high genetic similarity (28%-92%) and they did not separate from each other in UPGMA tree. Furthermore, urban and forest genotypes clustered together in principal component analysis
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
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