Carl Nielsen and Theories of Symphonism

NIELSEN COINCIDENCE, FIXED POINT AND ROOT THEORIES OF n-VALUED MAPS

Let (φ, ψ) be an (m,n)-valued pair of maps φ, ψ : X ( Y , where φ is an m-valued map and ψ is n-valued, on connected finite polyhedra. A point x ∈ X is a coincidence point of φ and ψ if φ(x) ∩ ψ(x) 6= ∅. We define a Nielsen coincidence number N(φ : ψ) which is a lower bound for the number of coincidence points of all (m,n)-valued pairs of maps homotopic to (φ, ψ). We calculate N(φ : ψ) for all ...

Carl Woese

Not long after Carl Woese died, I received a message from Robin Gutell asking if I would contribute an article to this issue of RNA Biology. While my admiration for Carl's contributions to biology knows no bounds, I did not know him well personally. For that reason I advised Robin to strike my name off the list of contributors and replace it with that of someone who is better qualified than I a...

Review of Mechanisms and Theories of Aging

Several factors have incentive role for study of aging which includes increasing of the average and maximum of human life span, the increase in percentage of elderly in the societies and proportion of the national expenditure utilized by them. The Recent views of aging indicating that aging is extremely a complex multifactorial process despite of earlier views about definite cause aging like ge...

Carl Djerassi: Chemist and entrepreneur

Nielsen Number and Differential Equations

In reply to a problem of Jean Leray (application of the Nielsen theory to differential equations), two main approaches are presented. The first is via Poincaré’s translation operator, while the second one is based on the Hammerstein-type solution operator. The applicability of various Nielsen theories is discussed with respect to several sorts of differential equations and inclusions. Links wit...