HETEROPHYLLY IN HIPPURIS, A PROBLEM IN IDENTIFICATION

1961 ◽  
Vol 39 (5) ◽  
pp. 1099-1116 ◽  
Author(s):  
Margaret E. McCully ◽  
Hugh M. Dale
Keyword(s):  
Water Relations ◽  
Leaf Morphology ◽  
Experimental Studies ◽  
Main Criterion ◽  
Leaf Form ◽  
Diverse Origin ◽  
Great Uniformity ◽  
Further Development ◽  
Foliar Morphology

Although the primordia of all types of leaves in Hippuris show no distinguishing characteristics until they are 50 microns long, their further development is strongly influenced by their environment. At maturity they can, for convenience, be thought of as belonging to one of five types, or some intermediate of these types. The five types of leaves are: rhizome, juvenile aquatic, adult aquatic, juvenile aerial, and adult aerial. Field and experimental studies indicate that the leaf form in Hippuris is influenced by light and the water relations between the plant and its environment. There is great uniformity of foliar morphology on plants from stocks of diverse origin when grown under uniform conditions, and there is wide diversity of foliar morphology on plants of the same stock material when grown under different environments in the laboratory. Thus the taxonomic subdivision of genus Hippuris into species, varieties, and forms using leaf morphology as the main criterion appears questionable.

scholarly journals Research of a contact impact of a root crop with a screw auger

2020 ◽  
Vol 66 (No. 1) ◽  
pp. 33-42
Author(s):  
Viktor Baranovsky ◽  
Olena Truchanska ◽  
Maria Pankiv ◽  
Valentina Bandura
Keyword(s):  
Process Model ◽  
Empirical Process ◽  
Experimental Studies ◽  
Kinematic Parameters ◽  
Fodder Beet ◽  
Root Crop ◽  
Cleaning System ◽  
Screw Diameter ◽  
Contact Impact ◽  
Further Development

The purpose of this research is the further development of the methodology and methods of optimising the parameters of root pile  combined cleaners of a root crop harvesting machine. We have conducted theoretical and experimental studies of the combined  cleaning system’s functioning process. By executing the analysis, we found the motion of the fodder beet through the working surfaces of the feeding conveyor and the auger installed above it. We have got an analytical and empirical process model for the fodder beet’s oblique sub-hit on the auger turn. It characterises the dependence of the total rate of the sub-hit coefficient of the technological  interaction of the roots and the depth of the root damage, which depend on the main parameters of the combined cleaning system. We found out the rational limits of the basic structural and kinematic parameters of the combined cleaning system by the provided minimum fodder beet damage. It is theoretically justified that the minimum damage to roots of the beet roots will be at a contact angle of zero (γ ≅ 0) or close to it. This condition is protected with the following combinations of parameters: a screw diameter of D = 0.4, 0.6, 0.8 m and a screw speed of n = 99, 72, 50 rpm, respectively.

scholarly journals Beyond the extreme: recovery of carbon and water relations in woody plants following heat and drought stress

2019 ◽  
Vol 39 (8) ◽  
pp. 1285-1299 ◽  
Author(s):  
Nadine K Ruehr ◽  
Rüdiger Grote ◽  
Stefan Mayr ◽  
Almut Arneth
Keyword(s):  
Heat Stress ◽  
Gas Exchange ◽  
Water Relations ◽  
Woody Plants ◽  
Leaf Gas Exchange ◽  
Experimental Studies ◽  
Drought Severity ◽  
Stress Recovery ◽  
Mild Stress ◽  
Post Stress

Abstract Plant responses to drought and heat stress have been extensively studied, whereas post-stress recovery, which is fundamental to understanding stress resilience, has received much less attention. Here, we present a conceptual stress-recovery framework with respect to hydraulic and metabolic functioning in woody plants. We further synthesize results from controlled experimental studies following heat or drought events and highlight underlying mechanisms that drive post-stress recovery. We find that the pace of recovery differs among physiological processes. Leaf water potential and abscisic acid concentration typically recover within few days upon rewetting, while leaf gas exchange-related variables lag behind. Under increased drought severity as indicated by a loss in xylem hydraulic conductance, the time for stomatal conductance recovery increases markedly. Following heat stress release, a similar delay in leaf gas exchange recovery has been observed, but the reasons are most likely a slow reversal of photosynthetic impairment and other temperature-related leaf damages, which typically manifest at temperatures above 40 °C. Based thereon, we suggest that recovery of gas exchange is fast following mild stress, while recovery is slow and reliant on the efficiency of repair and regrowth when stress results in functional impairment and damage to critical plant processes. We further propose that increasing stress severity, particular after critical stress levels have been reached, increases the carbon cost involved in reestablishing functionality. This concept can guide future experimental research and provides a base for modeling post-stress recovery of carbon and water relations in trees.

scholarly journals PROSPECTS OF DISK PUMP FOR MECHANICAL CIRCULATORY SUPPORT IN CARDIAC SURGERY (REVIEW)

2016 ◽  
Vol 18 (3) ◽  
pp. 68-73 ◽  
Author(s):  
A. M. Chernyavskiy ◽  
A. V. Fomichev ◽  
T. M. Ruzmatov ◽  
A. E. Medvedev ◽  
Yu. M. Prikhodko ◽  
...  
Keyword(s):  
Support Systems ◽  
Experimental Studies ◽  
Viscous Friction ◽  
Left Ventricular ◽  
Circulatory Support ◽  
Published Data ◽  
Technical Requirements ◽  
New Directions ◽  
Further Development ◽  
Mechanical Heart Support

The need of circulatory support systems in the treatment of chronic heart failure is increasing constantly, as 20% of the patients on the waiting list die every year. Despite the great need for mechanical heart support systems, the use of available systems is limited by its expensiveness. In addition, there is no one system that is 100% responsible to all medical and technical requirements and that would be completely safe for patient. Therefore, further research in the field of circulatory support systems considering health and technical requirements is relevant. One of the new directions in the study are disc pumps of viscous friction for liquid transporting, based on the Tesla pump principle. The operation principle of such pumps is based on the phenomenon of the boundary layer which is formed on the disk rotating in a fluid. There are experimental studies of models with different variants of the rotor suspension, various forms and numbers of the disks, forms of the pump housing. However, none of the above samples was brought to clinical trials. Furthermore, despite the potential of that model there have been no pumps of similar type used so far in circulatory support systems. Published data provide a basis for further development and testing of the pump model and allow hoping for leveling a number of significant shortcomings of modern left ventricular bypass systems. 

scholarly journals Xenotransplantation: history, problems and development prospects

2019 ◽  
Vol 11 (1) ◽  
pp. 37-54
Author(s):  
V. A. Gulyaev ◽  
M. Sh. Khubutiya ◽  
M. S. Novruzbekov ◽  
A. S. Mironov ◽  
O. D. Olisov ◽  
...  
Keyword(s):  
Genetic Engineering ◽  
Experimental Studies ◽  
Tissue Transplantation ◽  
Theoretical Research ◽  
Rejection Reaction ◽  
Xenograft Rejection ◽  
Scientific Section ◽  
History Of ◽  
Further Development ◽  
Development Prospects

The paper reviews the milestones and prerequisites in the history of the emergence and development of xenotransplantation. The currently existing barriers (immunological, infectious, genetic, ethical, and regulatory) to the development of this organ and tissue transplantation type have been studied. Available data on theoretical research and experimental studies have been reviewed. The prospects for performing xenotransplantation in various combination of species have been assessed. The forms and variants of the xenograft rejection reaction have been described. Genetic engineering approaches to overcoming xenoimmunological incompatibility are described. An assessment is made of ways to overcome existing barriers and prospects for the further development of xenotransplantation as a scientific section of transplantology.

State of the Science on Ultramarathon Running After a Half Century: A Systematic Analysis and Commentary

2020 ◽  
Vol 15 (7) ◽  
pp. 1052-1056
Author(s):  
Martin D. Hoffman
Keyword(s):  
Human Subjects ◽  
Experimental Studies ◽  
The United States ◽  
Annual Number ◽  
Topic Area ◽  
Systematic Analysis ◽  
Funding Opportunities ◽  
State Of The Science ◽  
Study Participants ◽  
Further Development

Purpose: To systematically examine scientific publishing related to ultramarathon running. Methods: PubMed-indexed publications through 2019 were identified in which the work involved data collection at or in association with an ultramarathon running event, included experimental running trials of ultramarathon duration using human subjects, focused on human ultramarathon runners as the study participants, or were directed at discussing some aspect of ultramarathon running or ultramarathon runners. The characteristics of each publication were tabulated. Results: A total of 616 indexed publications were identified, with the first being in 1970. A rapid increase in publications was seen by 2010 in association with increased participation in ultramarathon running, followed by a plateauing at around 49 annual publications from 2014 to 2018. Most (83.3%) publications were observational, and the mean annual number of 1.6 experimental studies did not change (P = .20) from 1999 to 2019. Most of the publications were related to physiological issues, and race performance was the largest topic area (21.8%). The largest percentage of publications came from authors from the United States, followed by authors from Switzerland. Conclusions: Research related to ultramarathon running has had a small presence in sport science and offers potential for further development. At present, publishing appears to be stable and without recent increased emphasis on experimental studies. Worthwhile research opportunities remain, particularly those where ultramarathons serve as a model for stress and could offer relevance to a wider population than ultramarathon runners, but such research appears challenged by relatively small participation in the activity and limited funding opportunities.

Soil water potential does not affect leaf morphology or cuticular characters important for palaeo-environmental reconstructions in southern beech, Nothofagus cunninghamii (Nothofagaceae)

2012 ◽  
Vol 60 (2) ◽  
pp. 87 ◽  
Author(s):  
Mark J. Hovenden ◽  
Jacqueline K. Vander Schoor
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Availability ◽  
Leaf Morphology ◽  
Soil Water Potential ◽  
Co2 Concentration ◽  
Environmental Reconstruction ◽  
Leaf Form ◽  
Southern Beech ◽  
The Impact

Leaf form is closely related to local prevailing abiotic conditions and thus the morphology of fossil and sub-fossil leaves is often used to reconstruct both historical and palaeo-environmental conditions. However, palaeo-environmental reconstruction is difficult because leaf form is controlled potentially by many interacting environmental factors such as temperature, CO2 concentration, light and water availability. We used a glasshouse trial to investigate the impact of water availability on the leaf and cuticle morphology of a species important for palaeo-environmental reconstruction, the southern beech, Nothofagus cunninghamii. We found that reducing soil water potential to –0.2 or –0.5 MPa had no impact on leaf form or cuticular characters, despite reducing leaf carbon assimilation and severely restricting plant growth. Although plant accession affected many leaf characters, there were few significant impacts of altitude of origin and no substantial interactions between altitude of origin and soil water potential. Thus, both cuticular and gross leaf morphology seem to be stable across a range of soil water potentials in this species, meaning that palaeo-environmental signals from this species are unlikely to be affected by changes in water availability.

Water Relations and Carbon‐14 Assimilation of Cotton with Different Leaf Morphology 1

Crop Science ◽  
1980 ◽  
Vol 20 (4) ◽  
pp. 421-426 ◽  
Author(s):  
E. Karami ◽  
D. R. Krieg ◽  
J. E. Quisenberry
Keyword(s):  
Water Relations ◽  
Leaf Morphology ◽  
Carbon 14

Cooling and heating of the fluid in the cylindrical volume

2022 ◽  
pp. 15-26
Author(s):  
Stanislav Tkachenko ◽  
Olha Vlasenko ◽  
Nataliia Rezydent ◽  
Dmytro Stepanov ◽  
Nataliia Stepanova
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Water Environment ◽  
Experimental Studies ◽  
The Body ◽  
Thermal Mode ◽  
Limited Information ◽  
Characteristic Features ◽  
Cylindrical Volume ◽  
Further Development

Experimental studies of the non-stationary heat exchange in the system «environment I – body II» have been carried out. It is established that in the body II, which consists of the fluid and thin-walled metal envelope, the characteristic features of the regular thermal mode occur, i.e., cooling (heating) rate of the body II- m = const; heat transfer coefficient between the water (environment I) and body II is practically stable α1 = const; uneven temperatures distribution coefficient in the body II ψ = const. This new notion of the heat transfer regularities in the body II is planned to apply for further development of the experimental-calculation method for the forecasting of the heat exchange intensity in the compound fluid media with limited information regarding thermophysical and rheological properties.

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