Exposure of man to chemical agents can occur intentionally, as in the treatment of disease, or inadvertently because the environment contains a wide range of synthetic or naturally occurring chemicals. The alkylating agents are a diverse group of compounds (Fig. 1) and comprise a good example of such xenobiotics, since much is known about their occurrence, and their biological effects include carcinogenicity, mutagenicity, toxicity and teratogenicity.Exposure to potentially carcinogenic alkylating agents such as nitrosamines may occur occupationally, from cigarette smoke, from (...) certain foodstuffs and even endogenously through the ingestion of the appropriate precursor chemicals.1 At the other extreme, the cytotoxic effects of agents such as the chloroethylating nitrosamides or mustards have been exploited in the design of certain antitumour drugs.2 The effectiveness of antitumour agents and the other, mostly adverse, biological effects of alkylating agents have been ascribed to their ability to damage cellular macromolecules, in particular DNA. This review concentrates on investigations carried out over the past two years on the role of DNA damage in carcinogenesis, but we shall see how recent advances in this area of research have also led to a better understanding of the mechanisms of the cytotoxic effects of alkylating antitumour agents. (shrink)

This is a collection of the key articles written by renowned Wittgenstein scholar, G.P. Baker, on Wittgenstein’s later philosophy, published posthumously. Following Baker’s death in 2002, the volume has been edited by collaborator and partner, Katherine Morris. Contains articles previously only available in other languages, and one previously unpublished paper. Completely distinct from the widely-known work Baker did with P.M.S. Hacker in the Analytical Commentary on the Philosophical Investigations.

In ‘Wittgenstein on Language and Rules’, Professor N. Malcolm took us to task for misinterpreting Wittgenstein's arguments on the relationship between the concept of following a rule and the concept of community agreement on what counts as following a given rule. Not that we denied that there are any grammatical connections between these concepts. On the contrary, we emphasized that a rule and an act in accord with it make contact in language. Moreover we argued that agreement in judgments and (...) in definitions is indeed necessary for a shared language. But we denied that the concept of a language is so tightly interwoven with the concept of a community of speakers as to preclude its applicabilty to someone whose use of signs is not shared by others. Malcolm holds that ‘This is an unwitting reduction of Wittgenstein's originality. That human agreement is necessary for “shared” language is not so striking a thought as that it is essential for language simpliciter.’ Though less striking, we believe that it has the merit of being a true thought. We shall once more try to show both that it is correct, and that it is a correct account of Wittgenstein's arguments. (shrink)

This chapter contains sections titled: The Tractatus and rules of logical syntax From logical syntax to philosophical grammar Rules and rule‐formulations Philosophy and grammar The scope of grammar Some morals.

In this paper, we have considered a dynamical model of Chlamydia disease with varying total population size, bilinear incidence rate and pulse vaccination strategy. We have defined two positive numbers $$R_{0}$$ R 0 and $$R_{1}$$ R 1. It is proved that there exists an infection-free periodic solution which is globally attractive if $$R_{0} 1.$$ R 1 > 1. The important mathematical findings for the dynamical behaviour of the Chlamydia disease model are also numerically verified using MATLAB. Finally epidemiological implications of (...) our analytical findings are addressed critically. (shrink)

The word, first attested in writers of the fifth century B.C., belongs to a large group of possessive adjectives in which are formed from ethnic names. A few of these occur in Homer () and in the early lyric poets, but examples become increasingly common in the fifth century and later; their characteristic function is to denote something as belonging to a people or city as a whole, as distinct from ethnic adjectives which are applied to persons.

The word , first attested in writers of the fifth century B.C., belongs to a large group of possessive adjectives in which are formed from ethnic names. A few of these occur in Homer () and in the early lyric poets , but examples become increasingly common in the fifth century and later; their characteristic function is to denote something as belonging to a people or city as a whole, as distinct from ethnic adjectives which are applied to persons.

The dictum ‘“ought” implies “can”’ has a status in moral philosophy in some respects like that of ‘a good player needs good co-ordination’ in talk about ball-games. Clearly, you say something important but not conclusive about proficiency in playing a ball-game when you say that it requires good co-ordination: similarly, you say something important but not conclusive about obligation when you say that it implies a certain possibility or power or ability. Each dictum is a reminder: the one about such (...) courses of physical instruction, the other about such exhortations to duty, as are worth persevering with. It would be hopeless to keep on teaching a boy the moves and tricks of rugby football if he could never co-ordinate well enough to get his eye in, so to speak. Correspondingly, it would be meaningless to recommend that someone ought to do something the specification of which involved a contradiction, and pointless to suggest that he ought to do something which, for quite general reasons, was not, and was certain to remain not, within his power. So each dictum expresses a bluff, no-nonsense wisdom which we should count on before involving ourselves in certain more detailed commitments. But probably this is as far as the comparison between the two sayings can well be taken. (shrink)

This chapter offers an essay on the evolution of evolvability. It investigates the most frequently cited arguments against the possibility that the evolution of evolvability might be the result of selection favoring more evolvable genotypes. The chapter argues that all these arguments have not been rigorously analyzed by their proponents, and are thus a self-inflicted blind spot in evolutionary biology, and indicates that there are no deep conceptual obstacles for population genetic theory to explain the evolution of evolvability. The very (...) focus on this subject will help shift the perspective of evolutionary biology toward a more holistic, systemic view of evolution. (shrink)