FURTHER STUDIES ON NATURAL SELECTION AMONG HYBRIDS OF CARDUUS ACANTHOIDES AND CARDUUS NUTANS

1964 ◽  
Vol 42 (12) ◽  
pp. 1605-1613 ◽  
Author(s):  
R. J. Moore ◽  
G. A. Mulligan
Keyword(s):  
Natural Selection ◽  
Chromosome Number ◽  
Parental Species ◽  
Experimental Studies ◽  
Great Decrease ◽  
Carduus Acanthoides ◽  
Carduus Nutans ◽  
Experimental Plots ◽  
Better Than ◽  
Made In

A third 5-year survey made in 1962 of Carduus acanthoides, C. nutans, and their hybrids in Grey Co., Ontario, revealed that a great decrease in these populations had occurred. C. acanthoides and hybrids similar to this species had survived better than C. nutans but very little spread of either species seemed to have occurred in 1957–1962. In experimental plots the hybrid has been made and backcrossed to the parental species. The species differ in chromosome number (C. acanthoides, 2n = 22; C. nutans, 2n = 16) and hybrids have intermediate numbers. Evidence was found from field and experimental studies that the progeny of the F1 hybrid included a greater proportion of seedlings with the higher chromosome numbers than with the lower and intermediate numbers. It is suggested that this selection may operate through the rejection of the longer chromosomes received from C. nutans, which, in certain zygotic combinations may constitute an excess of chromatin lethal to the zygote.

NATURAL SELECTION AMONG HYBRIDS BETWEEN CARDUUS ACANTHOIDES AND C. NUTANS IN ONTARIO

1961 ◽  
Vol 39 (2) ◽  
pp. 269-279 ◽  
Author(s):  
Gerald A. Mulligan ◽  
Raymond J. Moore
Keyword(s):  
Natural Selection ◽  
Morphological Variation ◽  
Natural Hybridization ◽  
Hybrid Index ◽  
Local Conditions ◽  
Carduus Acanthoides ◽  
Carduus Nutans ◽  
Waste Land ◽  
Southern Half

Natural hybridization is occurring between two introduced thistles, Carduus acanthoides L. and C. nutans L., in the southern half of Grey County, Ontario. The morphological variation of plants in 37 fields, including a field near Priceville previously studied in 1952, was evaluated by means of a hybrid index in 1957. Carduus nutans was first established in the hybrid area and C. acanthoides was introduced later, probably from the region northwest of Owen Sound, into waste land near Flesherton, where hybridization first occurred. Many large hybrid populations were found in the southern portion of Grey County and most of these hybrids were very similar to C. acanthoides in morphology. It was concluded that there is a numerical supremacy of acanthoides-type hybrid segregates in the hybrid area, and that such hybrids are better adapted for survival under local conditions than C. nutans and will probably supplant the latter species.

Hybridization of Carduus nutans and Carduus acanthoides (Compositae): morphological variation in F1 hybrids and backcrosses

1992 ◽  
Vol 70 (11) ◽  
pp. 2303-2309 ◽  
Author(s):  
S. I. Warwick ◽  
B. K. Thompson ◽  
L. D. Black
Keyword(s):  
Morphological Variation ◽  
Morphological Traits ◽  
Parental Species ◽  
F1 Hybrids ◽  
Carduus Acanthoides ◽  
Carduus Nutans ◽  
Naturally Occurring ◽  
Morphological Criteria ◽  
Hybrid Complex ◽  
Hybrid Classes

The aim of this study was to compare patterns of morphological variation in F1 hybrids and backcrosses obtained artifically in the greenhouse relative to the parental species Carduus acanthoides (2n = 22) and Carduus nutans (2n = 16), which form a naturally occurring hybrid complex in Grey County, Ontario. The identity of parental, hybrid, and backcross genotypes was confirmed using allozyme markers. The data were used to test for hybrid (H) intermediacy in morphological traits that differentiate the two parental taxa (acronyms A and N are used for C. acanthoides and C. nutans, respectively) and to determine patterns of variation on the same traits among the four classes of backcross plants (NH, HN, AH, and HA, seed × pollen parent, respectively). Canonical multivariate analysis indicated that in general, F1 hybrids had intermediate morphologies compared with parental genotypes, although differences were observed among characters with respect to the degree of morphological intermediacy of hybrids. The backcrosses were divided into two groups, i.e., those backcrossed with C. acanthoides (AH and HA) and those with C. nutans (NH and HN). However, backcrosses also showed considerable morphological overlap with F1 hybrids. These results exemplify the utility of joint comparisons of morphology and genotypic constitution (allozymes) in the hybridization studies, and they emphasize the limitations in describing hybrid classes solely by morphological criteria. Key words: Carduus nutans, Carduus acanthoides, hybrids, backcrosses, morphological variation.

Study of Ancient Land Boundaries at Tauric Chersonesos Using Satellite Images

2019 ◽  
Vol 25 (1) ◽  
pp. 44-58 ◽  
Author(s):  
Edgar A. Terekhin ◽  
Tatiana N. Smekalova
Keyword(s):  
Remote Sensing ◽  
Information Systems ◽  
Geographic Information Systems ◽  
Satellite Images ◽  
Agricultural Land ◽  
Remote Sensing Data ◽  
Field Surveys ◽  
The 1960S ◽  
Better Than ◽  
Made In

Abstract The near chora (agricultural land) of Tauric Chersonesos was investigated using multiyear remote sensing data and field surveys. The boundaries of the land plots were studied with GIS (Geographic Information Systems) technology and an analysis of satellite images. Reliable reconstruction of the borders has been done for 231 plots (from a total of about 380), which is approximately 53% of the Chersonesean chora. During the last 50 years, most of the ancient land plots have been destroyed by modern buildings, roads, or forests. However, in the 1960s, a significant part of the chora was still preserved. Changes in preservation with time were studied with the aid of satellite images that were made in 1966 and 2015. During that period, it was found that the number of plots with almost-complete preservation decreased from 47 to 0. Those land plots whose preservation was better than 50% dropped from 104 to 4. A temporal map shows this decline in preservation. It was found that the areas of land plots could be determined accurately with satellite images; compared to field surveys, this accuracy was about 99%.

Introducing Problem-based Learning to Special Needs Dentistry—A Case Study

2002 ◽  
Vol os9 (1) ◽  
pp. 9-13 ◽  
Author(s):  
Raman Bedi ◽  
Jackie A Champion ◽  
Roger Davies
Keyword(s):  
Special Needs ◽  
Problem Based Learning ◽  
Chi Square ◽  
Training And Education ◽  
Mixed Response ◽  
Conventional Teaching ◽  
The Subject ◽  
Better Than ◽  
Made In

Introduction In order to promote training and education in special-needs dentistry an attempt was made to introduce problem-based learning (PBL) as a method of postgraduate dental education. The aim of this paper was to review the principles of PBL and report on a case study using this methodology. Method The case study was of a PBL session, on the subject of ‘problems of obtaining appropriate dental care for people with epilepsy’, undertaken at a national conference. Delegates were asked to complete a pre- and post-session questionnaire on PBL and their attitudes to the session. Results The session received a mixed response. Only 33 (35%) thought the session was valuable and only 20 (31%) thought it was better than conventional teaching methods and yet over half (55%) said they would like to attend more PBL in special-needs dentistry. Professionals complementary to dentistry were more likely to find the PBL session of value and to prefer the method to a more conventional format than dentists were (chi-square=5.5, df=1, p<0.05 and chi-square=5.9, df=1, p<0.05 respectively). Conclusion Valuable feedback was received from delegates. This will enable improvements to be made in future courses so that the effectiveness of PBL can be optimised.

Snap! Recognising Implicit Actions in Static Point-Light Displays

Perception ◽  
10.1068/p6320 ◽  
2009 ◽  
Vol 38 (4) ◽  
pp. 613-616 ◽  
Author(s):  
Russell Reid ◽  
Anna Brooks ◽  
Duncan Blair ◽  
Rick van der Zwan
Keyword(s):  
Biological Motion ◽  
Neural Mechanisms ◽  
Point Light ◽  
Static Point ◽  
Better Than ◽  
Made In

Johansson (1973 Perception & Psychophysics14 201–211) suggested that point-light displays that are static—so-called ‘snapshots’—contain little or no information about the actor or their action. Here we present data that suggest even naive observers can perceive such information from static point-light arrays. Observers were able, at rates better than chance, to discriminate the directions of facing of sagittally viewed static point-light walkers. The data show also that, without feedback, performances improved with experience. Our data have implications for assumptions made in designing experiments with point-light displays and for models of the neural mechanisms mediating biological motion perceptions.

The Development of Wavelet Transform and its Application in Image Denoise

2013 ◽  
Vol 694-697 ◽  
pp. 2003-2008
Author(s):  
Ming Hong Dai
Keyword(s):  
Wavelet Transform ◽  
Image Denoising ◽  
Filter Bank ◽  
Experimental Studies ◽  
Visual Quality ◽  
Simulation Experiments ◽  
Design And Implementation ◽  
Direction Filter ◽  
Related Design ◽  
Better Than

The paper introduces Laplace pyramid, Ridgelet and Curvelet principle, structure and methods, and their denoising experimental studies. It also introduces the traditional direction filter of principle, structure and methodology, and the simulation experiments show that its image denoising PSNR is slightly lower than wavelet but denoising image visual quality is better than former. To that end, proposed a new direction filters that uniform direction filter banks and non-uniform direction filters, proved filter passband condition and related design and implementation issues were discussed. nonlinear experiment shows that the new direction filter bank was better than the wavelet.

scholarly journals Response of Recycled Brick Aggregate Concrete to High Temperatures

2019 ◽  
Vol 8 (10) ◽  
pp. 224-227
Keyword(s):  
Mechanical Properties ◽  
Air Pollution ◽  
Compressive Strength ◽  
Construction Industry ◽  
Fire Performance ◽  
Demolition Waste ◽  
Aggregate Concrete ◽  
Different Temperatures ◽  
Better Than ◽  
Made In

The abundant availability of demolition waste from construction industry is leading towards a significant problem of disposal, land and air pollution. The natural aggregate resources are also depleting due to development of construction activities. An attempt is made in this study to convert this waste into wealth by substituting the recycled brick from demolition waste to granite aggregate in production of the concrete. The granite aggregate (GA) is replaced with recycled brick aggregate (RBA) by 25% of its weight to produce M15 and M20 grades of concrete. The granite aggregate concrete (GAC) and recycled brick aggregate concrete (RBAC) were subjected to different temperatures between 100 to 1000oC for a duration of 3 hours and the mechanical properties such as compressive strength and flexural strength were examined to assess its fire performance. The response of RBAC is better than GAC at each temperature. The study revealed that the residual strength increases with the increase in grade of concrete at all temperatures.

scholarly journals Genome size versus geographic range size in birds

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10868
Author(s):  
Beata Grzywacz ◽  
Piotr Skórka
Keyword(s):  
Natural Selection ◽  
Chromosome Number ◽  
Genome Size ◽  
Body Mass ◽  
Generalized Least Squares ◽  
Geographic Range ◽  
Range Size ◽  
Geographic Ranges ◽  
Brain Mass ◽  
Terrestrial Vertebrates

Why do some species occur in small, restricted areas, while others are distributed globally? Environmental heterogeneity increases with area and so does the number of species. Hence, diverse biotic and abiotic conditions across large ranges may lead to specific adaptations that are often linked to a species’ genome size and chromosome number. Therefore, a positive association between genome size and geographic range is anticipated. Moreover, high cognitive ability in organisms would be favored by natural selection to cope with the dynamic conditions within large geographic ranges. Here, we tested these hypotheses in birds—the most mobile terrestrial vertebrates—and accounted for the effects of various confounding variables, such as body mass, relative brain mass, and geographic latitude. Using phylogenetic generalized least squares and phylogenetic confirmatory path analysis, we demonstrated that range size is positively associated with bird genome size but probably not with chromosome number. Moreover, relative brain mass had no effect on range size, whereas body mass had a possible weak and negative effect, and range size was larger at higher geographic latitudes. However, our models did not fully explain the overall variation in range size. Hence, natural selection may impose larger genomes in birds with larger geographic ranges, although there may be additional explanations for this phenomenon.

scholarly journals ANALISA UNJUK KERJA MESIN STEMPEL FLASH MADE IN TIONGKOK MEREK FLAZ TERHADAP MESIN STEMPEL FLASH MADE IN INDONESIA MEREK MD

2020 ◽  
Vol 2 (1) ◽  
pp. 13-18
Author(s):  
Slamet Raharjo ◽  
Massus Subekti ◽  
Imam Arif Raharjo
Keyword(s):  
Grounded Theory ◽  
Electricity Consumption ◽  
Operation Time ◽  
Electrical Energy ◽  
Quality Parameter ◽  
Theory Approach ◽  
Machine Performance ◽  
Work Method ◽  
Better Than ◽  
Made In

This research aimed to find out the work method of flash stamp machine made in Tiongkok brand Flaz and flash stamp machine made in Indonesia brand MD observed from each machine performance including colour stamp quality resulted, duration in its operation, as well as power and electricity consumption. The research method adopted is qualitative method with grounded theory approach. This research conducted in Enterprise of Flash Stamp Machine made in Indonesia brand MD on Jl. Lembang Baru I West Sudimara, Ciledug, Tangerang, Banten. The result drawn from work method research of both flash stamp machine are: First,   the stamp quality resulted by flash stamp machine brand MD was better than flash stamp machine brand MD. Second, the operation time of flash stamp machine brand MD was 4 second faster, that is 3 second, while flash sta mp machine brand Flaz was 4 second. Third, the electricity power consumption of flash stamp machine brand Flaz was smaller that is 136,62 watt, while brand Flaz was 392,34 watt. Fourth, the electrical energy consumption of flash stamp machine Flaz was smaller that is 888,39 Joule, while flash stamp machine brand MD was 1709,06. The conclusion drawn from work method research of flash stamp machine made in Tiongkok brand Flaz toward flash stamp machine made in Indonesia brand MD measured from stamp output quality parameter and operation time speed, so flash stamp machine made in Indonesia brand MD is better than flash stamp machine made in Tiongkok brand Flaz. Abstrak Penelitian ini bertujuan untuk mengetahui unjuk kerja mesin stempel flash made in Tiongkok merek Flaz terhadap mesin stempel flash made in Indonesia merek MD dilihat dari performa masing-masing mesin meliputi kualitas cap stempel warna yang dihasilkannya, lama waktu pengoperasiannya, pemakaian daya serta konsumsi energi listriknya. Metode penelitian yang di gunakan adalah metode kualitatif dengan pendekatan penelitian grounded theory. Penelitian ini dilakukan di Perusahaan Pembuatan Mesin Stempel Flash made In Indonesia merek MD di Jl. Lembang Baru I Kelurahan Sudimara Barat, Ciledug, Tangerang, Banten. Hasil yang diperoleh dari penelitian unjuk kerja kedua mesin stempel flash ini adalah :  Pertama, kualitas cap stempel yang dihasilkan mesin stempel flash merek MD lebih bagus dibandingkan mesin stempel flash merek Flaz. Kedua, lama waktu operasinya 4 detik lebih cepat mesin stempel flash merek MD yaitu selama 3 detik dan 4 detik untuk mesin stempel flash merek Flaz. Ketiga, daya listrik yang dibutuhkan lebih kecil me sin stempel flash merek Flaz yaitu sebesar 136,62 watt dan 392,34 Watt untuk merek Flaz. Keempat, konsumsi energi listrik yang dibutuhkan lebih kecil mesin stempel merek Flaz yaitu 888,39 Joule dan 1709,06 Joule untuk mesin stempel flash merek MD. Kesimpulan yang diperoleh dari penelitian unjuk kerja mesin stempel flash made in Tiongkok merek Flaz terhadap mesin stempel flash made in Indonesia merek MD diukur dari parameter kualitas hasil cap dan kecepatan waktu operasi maka mesin stempel flash made in Indonesia merek MD lebih bagus dari pada mesin stempel flash made in Tiongkok merek Flaz.

Experimental Study of Air Distribution Characteristics in Room of Stratum Ventilation under Two Kinds of Air Change Times

2013 ◽  
Vol 409-410 ◽  
pp. 668-672
Author(s):  
Yong Mei Xu ◽  
Jian Tang ◽  
Jun Han ◽  
Chu Qin Lin
Keyword(s):  
Experimental Study ◽  
Thermal Comfort ◽  
Experimental Studies ◽  
Air Distribution ◽  
Distribution Characteristics ◽  
Breathing Zone ◽  
Wind Speeds ◽  
Pollutant Concentrations ◽  
New Type ◽  
Better Than

Aimed at a new type of ventilation - stratum ventilation, air distributions at a breathing-zone in a model office were measured under kinds of air changes, the measure parameters in the experimental studies included temperatures, wind speeds and pollutant concentrations, based on which the thermal comfort at a breathing-zone were studied. Experimental results show that, the temperature, pollutant concentration and wind speeds in a breathing-zone under 5 times air changes are better than those under 6 times air changes. The calculating results of PMV and PPD indicate that the thermal comfort at a breathing-zone under 5 times air changes is better. The experimental study is instructive for the development of the ventilation.

Sign in / Sign up

Export Citation Format

Share Document