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The passage of the 1975 law to liberalize abortion in France was inevitable because of the inadequacy of the 1920 law. The new law was passed quickly at the end of 1974 and its rapid implementation on January 17, 1975, caught public health officials by surprise. Two benefits have resulted from the law's implementation: (a) abortion has become a medical act, reducing the incidence of illegal termination of pregnancy and its complications; and (b) it has limited the need to travel to more liberal countries for an abortion. Chief among the law's disadvantages are the nonapplication of certain of its sections, the absence of means to curb noncomplying physicians and a certain laxity in its application due to inadequate public knowledge of the risks involved in repeated abortions.
The philosophical or metaphysical architecture of Darwin's theory of evolution by natural selection is analyzed and discussed. It is argued that natural selection was for Darwin a paradigmatic case of a natural law of change -- an exemplar of what Ghiselin (1969) has called selective retention laws. These selective retention laws lie at the basis of Darwin's revolutionary world view. In this essay special attention is paid to the consequences for Darwin's concept of species of his selective retention laws. Although Darwin himself explicity supported a variety of nominalism, implicit in the theory of natural selection is a solution to the dispute between nominalism and realism. It is argued that, although implicit, this view plays a very important role in Darwin's theory of natural selection as the means for the origin of species. It is in the context of these selective retention laws and their philosophical implications that Darwin's method is appraised in the light of recent criticisms, and the conclusion drawn that he successfully treated some philosophical problems by approaching them through natural history. Following this an outline of natural selection theory is presented in which all these philosophical issues are highlighted.
The integrated rate law for the reaction of the nitrite reductase of Paracoccus denitrificans, a cytochrome cd, has been established for turnover assays using donor ferrocytochromes c and either nitrite or molecular oxygen as the ultimate acceptor. The time course for the concentration of ferrocytochrome follows the law: formula: (see text), where S is the concentration of donor ferrocytochrome c, So is the initial concentration, t is time, and u1, u2, and u3 are empirical parameters that are constant for a given experiment but depend upon the initial substrate concentration. In particular, all the u1 increase with decreasing initial ferrocytochrome concentration. Saturation of reaction rates at high donor ferrocytochrome concentrations was not observed. The parameter u1 was proportional to the enzyme concentration while u2 and u3 were not. The form of the integrated rate law and the behavior of the u1 impose severe restrictions on possible kinetic schemes for the activity of the enzyme. Contemporary mechanisms that have been proposed for mitochondrial oxidase aa3 are examined and found to be inadequate to explain the reactivity of cytochrome cd. The simplest interpretations of the cytochrome cd data suggest that the enzyme does not bind the ferri and ferro forms of donor cytochromes c with equal affinity and that the enzyme is subject to inhibition by a product of reaction. Eucaryotic horse cytochrome c reacts with the Paracoccus cytochrome cd with 77% of the activity when Paracoccus cytochrome c550 is used as the electron donor.
The observation that the amplitude of vestibular nystagmus grows as gaze is increased in the direction of the nystagmus fast phase and diminished with gaze in the opposite direction is known as "Alexander's law". We have developed an analog computer model to simulate Alexander's law in nystagmus secondary to dysfunction of a semicircular canal. The model utilizes relevant brainstem anatomy and physiology and includes gaze modulation of vestibular signals and push-pull integration to create eye position commands. When simulating normally functioning semicircular canals, the model produced no nystagmus. When simulating total impairment of the canal on one side with gaze directed maximally in the opposite direction, the model produced a large amplitude nystagmus with linear slow phases directed toward the affected side. As gaze was changed from far contralateral to ipsilateral, the nystagmus gradually diminished to zero. When simulating partial impairment of one canal, the nystagmus was smaller in amplitude and absent in ipsilateral gaze.
The character of the occlusal surfaces of teeth programs the functions of muscles that move the mandible and imposes specifications upon the dentist within which he must work in manipulating the patient's mandible. If he exceeds those specifications, protective responses that inhibit his efforts are elicited in the patient's musculature. A knowledge of the laws governing functions of the muscles that move the mandible enables the dentist to acquire mandibular-manipulation skills necessary for diagnosis and effective occlusal treatment. A model in which the dentist visualizes the patient, the patient's protective reflexes, the components of the patient's gnathostomatic system, and himself as four independent personalities participating in the jaw manipulation is a useful tool in acquiring mandibular-manipulation skills. This article is Part III of a series presented in four parts on the "Biologic Laws Governing Functions of Muscles That Move the Mandible."