Contrasting Cases: The Lotka-Volterra Model Times Three

How do philosophers of science make use of historical case studies? Are their accounts of historical cases purpose-built and lacking in evidential strength as a result of putting forth and discussing philosophical positions? We will study these questions through the examination of three different philosophical case studies. All of them focus on modeling and on Vito Volterra, contrasting his work to that of other theoreticians. We argue that the worries concerning the evidential role of historical case studies in philosophy are partially unfounded, and the evidential and hermeneutical roles of case studies need not be played against each other. In philosophy of science, case studies are often tied to conceptual and theoretical analysis and development, rendering their evidential and theoretic/hermeneutic roles intertwined. Moreover, the problems of resituating or generalizing local knowledge are not specific to philosophy of science but commonplace in many scientific practices—which show similarities to the actual use of historical case studies by philosophers of science

Ecological and genetic models of host-pathogen coevolution

A model is presented to analyse the forces that maintain genetic polymorphism in interactions between host plants and their pathogens. Genetic variability in hosts occurs for specific resistance to different pathogen races and variability in pathogens occurs for specific virulence to different host races. The model tracks both fluctuating population sizes and changing gene frequencies. Analyses over a range of parameters show that ecological and demographic factors, such as birth and death rates, often have a more profound effect on the amount of polymorphism than genetic parameters, such as the pleiotropic costs of resistance and virulence associated with different alleles. A series of simple measures are proposed to predict the amount of genetic polymorphism expected in particular host-pathogen interactions. These measures can be used to develop and test a comparative theory of genetic polymorphism in host-pathogen coevolution

Coefficients Of Relatedness In Sociobiology

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62673/1/288694a0.pd

Uniqueness and existence of positive solutions for the fractional integro-differential equation

© 2017, The Author(s).In this paper, we study the uniqueness and existence of positive solutions for the fractional integro-differential equation with the integral boundary value problem. By means of the Banach contraction principle and the Krasnoselskii fixed point theorem, the sufficient conditions on the uniqueness and existence of positive solutions are investigated. An example is given to illustrate the main results