Motor processes cannot be modeled by a single (unified) model. Instead, a number of models at different levels of description are needed. The concepts of control and control variable only make sense at the functional level. A clear distinction must be made between external models and internal models. General Systems Theory provides the framework for a proper treatment of these issues.

Alpha‐fetoprotein (AFP)AFP, alpha‐fetoprotein; T3R, thyroid hormone (triiodothyronine) receptor; RAR, retionic acid receptor; erbA, putative thyroid hormone receptor proto‐oncogene products; VDR, vitamin D receptor; MR, mineralocorticoid receptor; GR, glucocorticoid receptor; PR, progesterone receptor; AR, androgen receptor; HRE, hormone response element on DNA; RXR, retionic‐X‐receptor; RAP, receptor auxiliary (accessory) proteins; E, estrogen. is a tumor‐associated fetal marker, associated both with tumor growth and with birth defects. AFP, whose precise function is unknown, has been classified as belonging to a protein superfamily together with (...) albumin and vitamin D‐binding (Gc) protein. AFP has been shown to bind various ligands in vitro including fatty acids, estrogens, thyroid hormones and retinoic acids. The steroid/thyroid nuclear receptor superfamily of proteins has recently become a major focus of biomedical investigation regarding regulation of gene expression. These receptors are thought to bind to DNA‐hormone response elements (HRE) that affect growth, development, differentiation, reproduction and homeostasis. The HREs are known to share DNA sequences with the various members of the nuclear receptor superfamily. In the present report, the possibility of a leucine‐zipper dimerization (heptad) motif in the carboxy‐terminal third domain of both rodent and human AFP is postulated. The presence of nine such hydrophobic repeats in the third domain of the AFP molecule mimics the heptad dimerization repeats found in the retinoic acid, thyroid, e‐erbA and other members of the nuclear receptor superfamily. Computer analysis revealed that the most conservative matching occurred between AFP and the retinoic acid class of receptors. However, other superfamily members displayed 40–60% homology with 5 of 9 AFP heptads. These findings could provide a possible mechanism for explaining the growth‐regulatory properties (both inhibition and enhancement) that have been ascribed to AFP in the last decade. (shrink)

Professor Frankena mentions me as one of the participants in what he calls the Movement in moral philosophy, and I think he is right; I was so moving, or being moved along among others, ten years or so ago, and I think I find myself still inclined to so move, while recognising with regret, when I come to look back at it, that, as he courteously observes, “what such writers say is not as clear as one would like.” I embark (...) on commenting upon his lectures with considerable trepidation, however, for the reason that, while his own writing surely is as clear as one could reasonably hope for, I have had great difficulty in figuring out what exactly it is in the Movement that he substantially dissents from, and have the lurking suspicion that there may be something that I have just failed to see. Tentatively, though, I tend to think that the root of my difficulty has been that he offers, in opposition to the Movement, an account of these matters that is really, in the end, not intelligible; and my main task in this commentative piece will be to try to explain why I think that. (shrink)

Philosophy and philosophical workers play very important roles in the socialist society of the People's Republic of China. No longer is philosophy treated as an object of speculation; nor is it regarded as merely a method of applying theory. It is now considered to be a process of learning from the practical experience of the masses, a process of enriching the concrete life of the people, and a process of solving specific problems in remaking society and changing the world. Briefly (...) speaking, philosophy plays the important role of eliminating alienation and the possibility of alienation among men. On this basis, philosophical workers, like other intellectuals, are urged to unite with and learn from the masses — the industrial workers and the peasants. Many writings have focused on this Maoist point, which is exemplified in this issue by Kuan Feng's article. From this point of view, traditional philosophy, which fails to eliminate alienation and which in fact tends to create and justify alienation as defined by Marxist and Maoist ideology, is subjected to severe criticism. (shrink)

This article is an attempt to clarify a confusion in the brain death literature between logical sufficiency/necessity and natural sufficiency/necessity. We focus on arguments that draw conclusions regarding empirical matters of fact from conceptual or ontological definitions. Specifically, we critically analyze arguments by Tom Tomlinson and Michael B. Green and Daniel Wikler. which, respectively, confuse logical and natural sufficiency and logical and natural necessity. Our own conclusion is that it is especially important in discussing the brain death issue to observe (...) the distinction between logical and natural sufficiency/necessity in a strict fashion. (shrink)

Tunneling oscillations induced in a double quantum well by a monochromatic electromagnetic wave incident perpendicularly to the plane of the well, and polarized along the direction of its growth, are treated. For the wave frequency in proximity to the energy difference between two states of opposite symmetry, a periodic energy exchange between the wave and a carrier which moves from one energy state to the other is established. When the carrier starts from the low energy level it borrows energy from (...) the wave until it reaches the higher energy state. On its way the carrier performs current oscillations that cease whenever it reaches an eigenstate. Similarly, oscillation is required during the carrier's motion from the high to the low energy state for the photon emission in order that the radiation gets back the energy already given to the carrier. Thus an accelerating charge not only radiates, but also absorbs wave energy. When there prevails a considerable population difference between the two levels the possibility of quantum beat exits. (shrink)

In the opening sections of his Brahma-sutra-bhasya , Ramanuja makes a very forceful assault on Sankara's Advaita theory. This assault anticipates in a striking way modern western attacks on metaphysical religious positions, attacks which stem from Hume and are associated today with names like A. J. Ayer and Antony Flew. In this paper I wish to argue that certain aspects of Sankara's position, as enunciated in his Brahma-sutra-bhasya , suggest that Ramanunja's assault, and therefore by implication a modern western attack (...) on Sankara also, depends for its success on a misinterpretation of Sankara's views. I wish then to suggest a possible alternative interpretation of Sankara's Advaita in terms viable for today, drawing, though indirectly, on such writers as R. B. Braithwaite and R. M. Hare. An incidental implication of this paper is that these two philosophers of religion would meet less opposition from the religious if they were Hindu rather than Christian! A more important implication is that light could be thrown on the present religious controversy in the west by a study of Indian philosophy of religion, if only we were more disposed to treat it as a living tradition which might teach us something, rather than as an antique. (shrink)

In interpreting measurements of brain processes it is necessary to make the model used explicit. A concept such as attention cannot be used in the description of brain activities without a model of the relation of mental and neural processes.