Mechanical stimulation has a critical role in the development and maintenance of the skeleton. This function requires the perception of extracellular stimuli as well as their conversion into intracellular biochemical responses. This process is called mechanotransduction and is mediated by a plethora of molecular events that regulate bone metabolism. Indeed, mechanoreceptors, such as integrins, G protein‐coupled receptors, receptor protein tyrosine kinases, and stretch‐activated Ca2+ channels, together with their downstream effectors coordinate the transmission of load‐induced signals to the nucleus and the (...) expression of bone‐related genes. During the past decade, scientists have gained increasing insight into the molecular networks implicated in bone mechanotransduction. In the present paper, we consider the major signaling cascades and transcription factors that control bone and cartilage mechanobiology and discuss the influence of the mechanical microenvironment on the determination of skeletal morphology. (shrink)

Noise in behavior is often viewed as a nuisance: while the mind aims to take the best possible action, it is let down by unreliability in the sensory and response systems. How researchers study cognition reflects this viewpoint – averaging over trials and participants to discover the deterministic relationships between experimental manipulations and their behavioral consequences, with noise represented as additive, often Gaussian, and independent. Yet a careful look at behavioral noise reveals rich structure that defies easy explanation. First, both (...) perceptual and preferential judgments show that sensory and response noise may potentially only play minor roles, with most noise arising in the cognitive computations. Second, the functional form of the noise is both non-Gaussian and non-independent, with the distribution of noise being better characterized as heavy-tailed and as having substantial long-range autocorrelations. It is possible that this structure results from brains that are, for some reason, bedeviled by a fundamental design flaw, albeit one with intriguingly distinctive characteristics. Alternatively, noise might not be a bug but a feature: indeed, we suggest that noise is fundamental to how cognition works. Specifically, we propose that the brain approximates probabilistic inference with a local sampling algorithm, one that uses randomness to drive its exploration of alternative hypotheses. Reframing cognition in this way explains the rich structure of noise and leads to a surprising conclusion: that noise is not a symptom of cognitive malfunction but plays a central role in underpinning human intelligence. (shrink)

In this paper Popper formulates and discusses a new aspect of the theory of mind. This theory is partly based on his earlier developed interactionistic theory. It takes as its point of departure the observation that mind and physical forces have several properties in common, at least the following six: both are located, unextended, incorporeal, capable of acting on bodies, dependent upon body, capable of being influenced by bodies. Other properties such as intensity and extension in time may be added. (...) It is argued that a fuller understanding of the nature of forces is essential for the analysis of the mind-brain problem. The relative autonomy and indeterministic nature of mind is stressed. Indeterminism is treated in relation to a theorem of Hadamard. The computer theory of mind and the Turing test are criticized. Finally the evolution of mind is discussed. (shrink)

I first met Parmenides – together with Xenophanes, Heraclitus, and the other great Presocratics – in a German translation by Wilhelm Nestle, famous as the editor of the later editions of Zeller's magnum opus. I was 15 or 16 years old, and I was overwhelmed by the meeting. The verses that I liked best were Parmenides' story of Selene's love for radiant Helios . But I did not like it that the translation made the moon male and the sun female (...) , and it occurred to me to give the couplet in German a title like ‘Moongoddess and Sungod’, or perhaps ‘Selene and Helios’, in order to rectify the genders. So I began fiddling about with the translations. The volume, which I still possess, shows many traces of this. (shrink)

There is a great deal of interest in the relation between the status of women and fertility—by humanists, academics and policy-makers concerned with bringing about fertility declines. The three aspects of women's status most frequently linked to fertility are their education, employment and type of husband-wife interaction. Research to date has not given us a clear and consistent explanation of these relationships and has not confirmed causality. The effects of these three factors on fertility vary considerably across national boundaries and (...) even within different sectors of the same society. Some of the assumptions held by both researchers and policymakers must be re-thought in the interests of more useful future research and of sounder policy. (shrink)