A unique diploid – triploid contact zone provides insights into the evolutionary mechanisms of cytotype coexistence in flowering rush (Butomus umbellatus)

2022 ◽  
pp. 125659
Author(s):  
Martin Čertner ◽  
Jan Rydlo ◽  
Matej Dudáš ◽  
Zdenka Hroudová
Keyword(s):  
Contact Zone ◽  
Evolutionary Mechanisms

Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part IV: Laboratory Measurement of Mechanical Properties and Mechanical Actions of Tires Relating to Treadwear

1986 ◽  
Vol 14 (4) ◽  
pp. 264-291
Author(s):  
K. L. Oblizajek ◽  
A. G. Veith
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
Contact Zone ◽  
Flexural Rigidity ◽  
Comprehensive Evaluation ◽  
Shear Stiffness ◽  
Shear Stresses ◽  
Lateral Shear ◽  
Band Bending ◽  
Tread Rubber

Abstract Treadwear is explained by specific mechanical properties and actions of tires. Rubber shear stresses in the contact zone between the tire and the road become large at large slip angles. When normal stresses are insufficient to prevent sliding at the rear of the footprint, wear occurs at a rate that depends on test severity. Two experimental approaches are described to relate treadwear to tire characteristics. The first uses transducers imbedded in a simulated road surface to obtain direct measurements of contact stresses on the loaded, freely-rolling, steered tires. The second approach is developed with the aid of a simple carcass, tread-band, tread-rubber tire model. Various tire structural configurations; characterized by carcass spring rate, edgewise flexural band stiffness, and tread rubber shear stiffness; are simulated and lateral shear stress response in the contact zone is determined. Tires featuring high band stiffness and low carcass stiffness generate lower lateral shear stress levels. Furthermore, coupling of tread-rubber stiffness and band flexural rigidity are important in determining level of shear stresses. Laboratory measurements with the described apparatus produced values of tread-band bending and carcass lateral stiffness for several tire constructions. Good correlation is shown between treadwear and a broad range of tire stiffness and test course severities.

Stibnite vein from Dębowina near Bardo (polish Sudetes)

2013 ◽  
Vol 2 (1) ◽  
pp. 28-33
Author(s):  
Piotr Kotula
Keyword(s):  
Contact Zone

Abstract In the contact zone of the Bardo Structure and Kłodzko-Złoty Stok Intrusion and Kłodzko Metamorphic, metasomatic orebearing quartz-carbonate veins rich in Sb, Zn, Cu, Ag, Au, Pb are present. In 1771 the mine ,,Reiche Silber Gluck” within stibnite vein was founded in Dębowina near Bardo. Its entrance was discovered again in 2007. The stibnite vein is mainly build of stibnite and sphalerite and of quartz and dolomite rich in Mn. Stibnite crystallizes as columnar or forming radiate centres and aciculars. Its crystals reach size to 2 mm. Sphalerite appears as individual anhedral and polymineralic grained concentrations reaching size to 2,5 mm. Earlier pyrite and arsenopyrite crystallized - they occur locally in this deposit. There were found also in the deposit tetrahedrite rich in Ag, what wasn't reported earlier in studies from the mine in Dębowina.

Evolution of Angiosperm Pollen: 8. Lamiids

2020 ◽  
Vol 105 (3) ◽  
pp. 323-376
Author(s):  
Li-E Yang ◽  
Lu Lu ◽  
Kevin S. Burgess ◽  
Hong Wang ◽  
De-Zhu Li
Keyword(s):  
Maximum Likelihood ◽  
Pollen Morphology ◽  
Pollen Size ◽  
State Transitions ◽  
Character State ◽  
Evolutionary Mechanisms ◽  
Pollen Characters ◽  
Exine Ornamentation ◽  
Shape Class ◽  
Pollen Character

Lamiids, a clade composed of approximately 15% of all flowering plants, contains more than 50,000 species dispersed across 49 families and eight orders (APG IV, 2016). This paper is the eighth in a series that analyzes pollen characters across angiosperms. We reconstructed a maximum likelihood tree based on the most recent phylogenetic studies for the Lamiids, comprising 150 terminal genera (including six outgroups) and covering all eight orders and 49 families within the clade. To illustrate pollen diversity across the Lamiids, pollen grains from 22 species (22 genera in 14 families) were imaged under light, scanning, and transmission electron microscopy. Eighteen pollen characters that were documented from previous publications, websites, and our new observations were coded and optimized onto the reconstructed phylogenetic tree using Fitch parsimony, maximum likelihood, and hierarchical Bayesian analysis. Pollen morphology of the Lamiids is highly diverse, particularly in shape class, pollen size, aperture number, endoaperture shape, supratectal element shape, and tectum sculpture. In addition, some genera show relatively high infrageneric pollen variation within the Lamiids: i.e., Coffea L., Jacquemontia Choisy, Justicia L., Pedicularis L., Psychotria L. nom. cons., Sesamum L., Stachytarpheta Vahl, and Veronica L. The plesiomorphic states for 16 pollen characters were inferred unambiguously, and 10 of them displayed consistent plesiomorphic states under all optimization methods. Seventy-one lineages at or above the family level are characterized by pollen character state transitions. We identified diagnostic character states for monophyletic clades and explored palynological evidence to shed light on unresolved relationships. For example, palynological evidence supports the monophyly of Garryales and Metteniusaceae, and sister relationships between Icacinaceae and Oncothecaceae, as well as between Vahliales and Solanales. The evolutionary patterns of pollen morphology found in this study reconfirm several previously postulated evolutionary trends, which include an increase in aperture number, a transition from equatorially arranged apertures to globally distributed ones, and an increase in exine ornamentation complexity. Furthermore, there is a significant correlation between pollen characters and a number of ecological factors, e.g., pollen size and pollination type, pollen ornamentation and pollination type, and shape class and plant growth form. Our results provide insight into the ecological, environmental, and evolutionary mechanisms driving pollen character state changes in the Lamiids.

Diachronic trends in the evolution of civilizations in the Nile valley

2018 ◽  
pp. 37-49
Author(s):  
Элеонора Кормышева ◽  
Eleonora Kormysheva
Keyword(s):  
Material Culture ◽  
Social History ◽  
Contact Zone ◽  
Scientific Discourse ◽  
Cultural Development ◽  
Nile Valley ◽  
Mediterranean World ◽  
The Mediterranean

The diachronic trends in socio-economic and cultural development of the societies in the Nile valley are revealed based on the materials from Giza necropolis (the 3rd millennium BC) and the settlement of Abu Erteila (1st century AD). The research made it possible to trace the typological similarities in the evolution of the studied societies in cultural and historical contexts. The main fields of the research were epigraphy, iconography, social history, and material culture. Many previously unknown monuments discovered by Russian archaeologists in Egypt and Sudan were introduced into scientific discourse. The basis was created for studying the Nile valley as a contact zone between the Mediterranean world and Africa.

Evolutionary Transitions in Mode of Development

2018 ◽  
Keyword(s):  
Analytical Approach ◽  
Large Body ◽  
Functional Variation ◽  
Evolutionary Mechanisms ◽  
Evolutionary Transitions ◽  
Comparative Phylogenetics ◽  
Mode Of Development ◽  
Larval Traits ◽  
Complex Characters

In the large body of literature on ecological and evolutionary mechanisms underlying transitions between planktotrophy and lecithotrophy, the focus has typically covered long evolutionary timescales; that is, evolution of complex larval traits is generally discussed in the context of phylogenetic patterns detectable at the level of families, classes, or phyla. An analytical approach incorporating comparative phylogenetics is increasingly used to address these long-view questions. Here, we discuss what has been learned from taking a comparative phylogenetic approach and the limitations of this approach. We propose that approaches based on a closer view—that is, analyses that focus on genetic, morphological, and functional variation among individuals, populations, or closely related congeners—have greater potential to answer questions about mechanisms underlying the loss and regain of major complex characters such as feeding larvae.

Reproductive behavior

2018 ◽  
Author(s):  
Rachel Olzer ◽  
Rebecca L. Ehrlich ◽  
Justa L. Heinen-Kay ◽  
Jessie Tanner ◽  
Marlene Zuk
Keyword(s):  
Sexual Selection ◽  
Sexual Conflict ◽  
Female Choice ◽  
Reproductive Behavior ◽  
Mating Systems ◽  
Insect Behavior ◽  
Sequential Approach ◽  
Evolutionary Mechanisms ◽  
Anatomy And Physiology ◽  
Males And Females

Sex and reproduction lie at the heart of studies of insect behavior. We begin by providing a brief overview of insect anatomy and physiology, followed by an introduction to the overarching themes of parental investment, sexual selection, and mating systems. We then take a sequential approach to illustrate the diversity of phenomena and concepts behind insect reproductive behavior from pre-copulatory mate signalling through copulatory sperm transfer, mating positions, and sexual conflict, to post-copulatory sperm competition, and cryptic female choice. We provide an overview of the evolutionary mechanisms driving reproductive behavior. These events are linked by the economic defendability of mates or resources, and how these are allocated in each sex. Under the framework of economic defendability, the reader can better understand how sexual antagonistic behaviors arise as the result of competing optimal fitness strategies between males and females.

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