Use of Multivariate Mathematical Methods for the Evaluation of Retention Data Matrices

2021 ◽  
pp. 1-63
Author(s):  
Tibor Cserháti ◽  
Esther Forgács
Author(s):  
E.J. Prendiville ◽  
S. Laliberté Verdon ◽  
K. E. Gould ◽  
K. Ramberg ◽  
R. J. Connolly ◽  
...  

Endothelial cell (EC) seeding is postulated as a mechanism of improving patency in small caliber vascular grafts. However the majority of seeded EC are lost within 24 hours of restoration of blood flow in previous canine studies . We postulate that the cells have insufficient time to fully develop their attachment to the graft surface prior to exposure to hemodynamic stress. We allowed EC to incubate on fibronectin-coated ePTFE grafts for four different time periods after seeding and measured EC retention after perfusion in a canine ex vivo shunt circuit.Autologous canine EC, were enzymatically harvested, grown to confluence, and labeled with 30 μCi 111 Indium-oxine/80 cm 2 flask. Four groups of 5 cm x 4 mm ID ePTFE vascular prostheses were coated with 1.5 μg/cm.2 human fibronectin, and seeded with 1.5 x 105 EC/ cm.2. After seeding grafts in Group 1 were incubated in complete growth medium for 90 minutes, Group 2 were incubated for 24 hours, Group 3 for 72 hours and Group 4 for 6 days. Grafts were then placed in the canine ex vivo circuit, constructed between femoral artery and vein, and subjected to blood flow of 75 ml per minute for 6 hours. Continuous counting of γ-activity was made possible by placing the seeded graft inside the γ-counter detection crystal for the duration of perfusion. EC retention data after 30 minutes, 2 hours and 6 hours of flow are shown in the table.


1966 ◽  
Vol 11 (7) ◽  
pp. 360-360
Author(s):  
Q. McN.

2012 ◽  
pp. 82-95 ◽  
Author(s):  
D. Foley

Mathematical methods are only one moment in a layered process of theory generation in political economy, which starts from Schumpeterian vision, progresses to the identification of relevant abstractions, the development of mathematical and quantitative models, and the confrontation of theories with empirical data through statistical methods. But today the relevant abstract problems of political economy are modified to fit available mathematical tools. The role of empirical research in disciplining theoretical speculation, on which the scientific traditions integrity rests, was undermined by specific limitations of nascent econometric methods, and usurped by ex cathedra methodological fiats of theorists. These developmentssystematically favored certain ideological predispositions of economicsas a discipline. There is abundant room for New Thinking in political economy starting from the vision of the capitalist economy as a complex, adaptive system far from equilibrium, including the development of the theory of statistical fluctuations for economic interactions, redirection of macroeconomics and financial economics from path prediction toward an understanding of the qualitative properties of the system, introduction of constructive and computable methods into economic modeling, and the critical reconstruction of econometric statistical methods.


Author(s):  
William Hoppitt ◽  
Kevin N. Laland

Many animals, including humans, acquire valuable skills and knowledge by copying others. Scientists refer to this as social learning. It is one of the most exciting and rapidly developing areas of behavioral research and sits at the interface of many academic disciplines, including biology, experimental psychology, economics, and cognitive neuroscience. This book provides a comprehensive, practical guide to the research methods of this important emerging field. It defines the mechanisms thought to underlie social learning and demonstrate how to distinguish them experimentally in the laboratory. It presents techniques for detecting and quantifying social learning in nature, including statistical modeling of the spatial distribution of behavior traits. It also describes the latest theory and empirical findings on social learning strategies, and introduces readers to mathematical methods and models used in the study of cultural evolution. This book is an indispensable tool for researchers and an essential primer for students.


2020 ◽  
Vol 18 (4) ◽  
pp. 48-58
Author(s):  
Vladislav V. Spitsyn ◽  
Alexander A. Mikhal'chuk ◽  
Anastasia A. Bulykina ◽  
Svetlana N. Popova ◽  
Irina E. Nikulina

Leading world countries view innovative development and high-tech business as an opportunity to overcome economic stagnation and decline in economic growth. One of the modern trends in the analysis of high-tech development is the study of high-tech knowledge-intensive service industries and their development in times of crisis. The purpose of the paper is to identify patterns of development of large, medium and small enterprises in high-tech service industries in Russia during periods of crisis. Economic and economic-mathematical methods of analysis are applied to the formed samples of enterprises. The research period is 2013-2017. The financial indicators of enterprises were adjusted for the level of accumulated inflation in relation to 2013. According to results, large and medium-sized enterprises showed insignificant or weak significant positive dynamics of revenue during all years of the crisis period. The crisis period did not lead to a decrease in the revenue of these groups of enterprises. The acute phase of the crisis (2014-2015) had a pronounced negative impact on the group of small enterprises in all studied industries, but they successfully recovered in 2016-2017 and reached the pre-crisis level of revenue. The total revenue by industries and groups of enterprises in 2017 became higher than in 2013, and its growth rates were significant for many groups of enterprises, which indicates a successful overcoming of the crisis period and signs of growth in high-tech service industries. Our study shows the need for state support for small businesses in high-tech service industries in crisis conditions, and identifies the possibilities of adaptation of enterprises in these industries to an unfavorable external environment. Our results may be useful for the purposes of government stimulation of economic development in the current environment.


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