The conceptual and investigative tools for the analysis of social behavior can be expanded by integrating biological theory, control systems theory, and Pavlovian conditioning. Biological theory has focused on the costs and benefits of social behavior from ecological and evolutionary perspectives. In contrast, control systems theory is concerned with how machines achieve a particular goal or purpose. The accurate operation of a system often requires feed-forward mechanisms that adjust system performance in anticipation of future inputs. Pavlovian conditioning (...) is ideally suited to subserve this function in behavioral systems. Pavlovian mechanisms have been demonstrated in various aspects of sexual behavior, maternal lactation, and infant suckling. Pavlovian conditioning of agonistic behavior has been also reported, and Pavlovian processes may likewise be involved in social play and social grooming. Several further lines of evidence indicate that Pavlovian conditioning can increase the efficiency and effectiveness of social interactions, thereby improving their cost/benefit ratio. We extend Pavlovian concepts beyond the traditional domain of discrete secretory and other physiological reflexes to complex real-world behavioral interactions and apply abstract laboratory analyses of the mechanisms of associative learning to the daily challenges animals face as they interact with one another in their natural environments. Key Words: aggression; biological theory; control theory; feed-forward mechanisms; learning theory; nursing and lactation; Pavlovian conditioning; sexual behavior; social behavior; social grooming; social play. (shrink)

The specific mechanisms whereby Pavlovian conditioning leads to adaptive behavior need to be elaborated. There is no evidence that it is via reduction in the “destabilizing effect that time lags have on feedback control” (Domjan et al. 2000, sect. 3.3). The adaptive value of Pavlovian conditioning goes well beyond the regulation of social behavior.

Recent developments in psychology and neuroscience suggest away to link the mental phenomenon of visual awareness with specific neural processes. Here, it is argued that the feed-forward activation of cells in any area of the brain is not sufficient to generate awareness, but that recurrent processing, mediated by horizontal and feedback connections is necessary. In linking awareness with its neural mechanisms it is furthermore important to dissociate phenomenal awareness from visual attention or decision processes.

Prehensity -- Intensity -- Potentiality -- Sensibility.

This paper explores the consequences of the theoretical forward activation enzymatic pathway A 0 A 1 A 2 A 3 where E 1 convents A 0 to A 1, E 2 converts A 1 to A 2 and E 3 converts A 2 to A 3. A 0, which is environmentally determined, also serves to activate (or modulate) the activity of E 3 in such a way as to keep the concentration of A 2 ([A 2]) constant at a (...) particular set-point value. For mathematical simplicity, first order rate kinetics are used where k 1, k 2 and k 3 are the rate constants for E 1, E 2, and E 3 respectively. It is shown that if k 3 is modulated appropriately so as keep [A 2] at the setpoint value with a changing upstream [A 0], then the modulation of k 3 must be anticipatory of the dynamics of the biochemical pathway. In other words, the rate of change of k 3, will be a function of [A 0], k 1, k 2, k 3, and the set-point value of [A 2]. If the modulation of k 3 does not perfectly model (anticipate) the reaction pathway of which it is a part, then the actual [A 2] will deviate from the set-point value. This type of anticipatory feed-forward activation may represent an important aspect of biological organization. (shrink)

Feed-forward Pavlovian conditioning can serve as a proximate mechanism for the evolution of social behavior. Feed-forward can provide the impetus for animals to associate other individuals' presence, and cooperation with them, with the acquisition of resources, whether or not the animals are genetically related. Other social behaviors such as play and grooming may develop as conditioned stimuli in feed-forward social systems.

Pavlovian feed-forward mechanisms represent an individual perspective that ignores how repeated interactions between the same individuals lead to social relationships. These can determine social cues, coordinated behaviors, asymmetries between partners, and physiological and emotional states associated with social interaction.

The energy sector contributes approximately two-thirds of global greenhouse gas emissions. In this context, the sector must adapt to new supply and demand networks for all future energy sources. The ongoing transformation in the European energy field is driven by the ambition of the European Union to reach the climate objectives set for 2030. The main actions are increasing renewable energy production, adapting transition fuels like natural gas to reduce emissions, improving energy efficiency across all economic sectors, prioritizing building, transportation, (...) and industry, developing Carbon Capture and Storage technologies, and ensuring universal access to clean and affordable energy. The significant changes envisaged in the energy sector to increase renewable energy production and consumption require improved integration and more use of predictive tools to support stakeholders' decision-making processes. This article presents a case study to assess the performance of predictive models based on a Feed-Forward Neural Network architecture that employ Root Mean Squared Propagation as their optimization function in terms of choosing the most appropriate activation function for this kind of data input and output. The training and testing phases of the models use data about building energy consumption. The lowest training time and Root Mean Square Error values were similar for Rectified Linear Unit and Tanh activation functions. The model with the Rectified linear Unit activation function performed best. (shrink)

The validity of assessment programs is increasingly important in higher education. Existing approaches to assessment are problematic because they eitherfail to provide timely feedback or have suspect measurement issues. We propose a feed-forward assessment model to help overcome these two limitations oftraditional assessment approaches.

An incoherent feed‐forward loop (FFL) is one of the most‐frequently observed motifs in biomolecular regulatory networks. It has been thought that the incoherent FFL is designed simply to induce a transient response shaped by a ‘fast activation and delayed inhibition’. We find that the dynamics of various incoherent FFLs can be further classified into two types: time‐dependent biphasic responses and dose‐dependent biphasic responses. Why do the structurally identical incoherent FFLs play such different dynamical roles? Through computational studies, we (...) show that the dynamics of the two types of incoherent FFLs are mutually exclusive. Following from further computational results and experimental observations, we hypothesize that incoherent FFLs have been optimally designed to achieve distinct biological function arising from different cellular contexts. Additional Supporting Information may be found in the online version of the article. BioEssays 30:1204–1211, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

We applaud Domjan et al. for providing an elegant account of Pavlovian feed-forward mechanisms in social behavior that eschews the pitfall of purposivism. However, they seem to imply that they have provided a complete account without provision for operant conditioning. We argue that operant conditioning plays a central role in social behavior, giving examples from fish and infant behavior.

The extent to which Pavlovian feed-forward mechanisms operate in primates is debatable. Monkeys and apes are long-lived, usually gregarious, and intelligent animals reliant on learned behavior. Learning occurs during play, mother-infant interactions, and grooming. We address these situations, and are hesitant to accept Domjan et al.'s reliance on Pavlovian conditioning as a major operant in primates.

The target article provides a useful investigative model for studying social behaviors, but it falls short of establishing a more comprehensive conceptual framework for understanding complex social inter- actions. Social behaviors such as play involve a dynamic and complex interplay between two or more organisms. Even when feed-forward mechanisms are taken into account and the model is anchored to evolutionary theory, the utility of this model is still limited by the conspicuous absence of neurobiological theory and data.

The problem of cortical integration is described and various proposed solutions, including grandmother cells, cell assemblies, feed-forward structures, RAAM and synchronization, are reviewed. One method, involving complex attractors, that has received little attention in the literature, is explained and developed. I call this binding through annexation. A simulation study is then presented which suggests ways in which complex attractors could underlie our capacity to reason. The paper ends with a discussion of the efficiency and biological plausibility of the (...) proposals as integration mechanisms for different regions and functions of the brain. (shrink)

to small scales. Further, it is often useful to describe motor control and sensorimotor coordination in terms of external elds such as force elds and sensory images. We survey the basic concepts of eld computation, including both feed-forward eld operations and eld dynamics resulting from recurrent connections. Adaptive and learning mechanisms are discussed brie y. The application of eld computation to motor control is illustrated by several examples: external force elds associated with spinal neurons, population coding of (...) direction in motor cortex, continuous transformation of direction elds, and linear gain elds and coordinate transformations in posterior parietal cortex. Next we survey some eld-based representations of motion, including direct, Fourier, Gabor and wavelet or multiresolution representations. Finally we consider brie y the application of these representations to constraint satisfaction, which has many applications in motor control. (shrink)

Discovery proceeds in stages of construction, evaluation, and revision. Each of these stages is constrained by what is known or conjectured about what is being discovered. A new characterization of mechanism aids in specifying what is to be discovered when a mechanism is sought. Guidance in discovering mechanisms may be provided by the reasoning strategies of schema instantiation, modular subassembly, and forward/backward chaining. Examples are found in mechanisms in molecular biology, biochemistry, immunology, and evolutionary biology.

Discovery proceeds in stages of construction, evaluation, and revision. Each of these stages is constrained by what is known or conjectured about what is being discovered. A new characterization of mechanism aids in specifying what is to be discovered when a mechanism is sought. Guidance in discovering mechanisms may be provided by the reasoning strategies of schema instantiation, modular subassembly, and forward/backward chaining. Examples are found in mechanisms in molecular biology, biochemistry, immunology, and evolutionary biology.

In the first section of the article, we examine some recent criticisms of the connectionist enterprise: first, that connectionist models are fundamentally behaviorist in nature (and, therefore, non-cognitive), and second that connectionist models are fundamentally associationist in nature (and, therefore, cognitively weak). We argue that, for a limited class of connectionist models (feed-forward, pattern-associator models), the first criticism is unavoidable. With respect to the second criticism, we propose that connectionist modelsare fundamentally associationist but that this is appropriate for (...) building models of human cognition. However, we do accept the point that there are cognitive capacities for which any purely associative model cannot provide a satisfactory account. The implication that we draw from is this is not that associationist models and mechanisms should be scrapped, but rather that they should be enhanced.In the next section of the article, we identify a set of connectionist approaches which are characterized by “active symbols” — recurrent circuits which are the basis of knowledge representation. We claim that such approaches avoid criticisms of behaviorism and are, in principle, capable of supporting full cognition. In the final section of the article, we speculate at some length about what we believe would be the characteristics of a fully realized active symbol system. This includes both potential problems and possible solutions (for example, mechanisms needed to control activity in a complex recurrent network) as well as the promise of such systems (in particular, the emergence of knowledge structures which would constitute genuine internal models). (shrink)

A methodology is proposed as a tool for explanation of form in zoomorphology, in particular its design, diversity, and transformation. An alternate use of descriptive, inductive/comparative, and deductive methods is suggested. The basic concepts required are summarized. Following an extensive anatomical analysis a specific deductive methodology is developed, comprising three major parts: 1) Formal analysis of systems, using optimal design. 2) Transformation of an initial system's model by simulating modifications via maximizing the model for specific functional requirements. 3) Testing by (...) comparison of deduced modifications with real systems having the maximized functional capacity, trends in specific morphoclines, and empirical analogues from technology.The methodology produces a morpho-space of modifications that has the form of branching pathways. That pattern results from innovation, bifurcation, and radiation moments in the deduction. The morpho-space is converted in a mechano-space by including next to constructional characters those of operation and rolefulfilment. If the initial system is verified as the ancestor and the transformation-function is verified as the evolutionary theme of change, the explanation turns -in addition to a function anatomical one- also into an evolutionary one. The method is illustrated by reviewing some recent analyses about avian feeding: maximization of avian pecking for probing and filter feeding capacities. (shrink)

This paper is one of several contributions in a series, illustrating the application of a specific deductive methodology to explain diversity of form. The methodology facilitates the explanation of feeding morphologies in various ducks as a transformation of the mallard's feeding design maximized for specific proportions of performance that are contributed by pecking and filter feeding mechanisms.The earlier described anatomy and formal analyses of the three mechanisms in the mallard served as the initial conditions used in simulation models. (...) Four elements of the feeding system were chosen that play a major role in all three mechanisms. For each element, the main parameter was selected: storage capacity of the rostral mouth cavity, transport capacity of the rostral mouth tube, storage capacity of the caudal mouth cavity and transport capacity of the caudal mouth tube. The boundary conditions for the simulation were determined from internal organismic constraints. The total food uptake of the mallard was regarded as the function to be maximized. This object function is the summation of the food uptake by one second of pecking and one second of filter feeding. The drinking mechanism was shown not to interfere, since that mechanism operates sufficiently whenever the pumping mechanism works properly. (shrink)

The notion of “hierarchy” is one of the most commonly posited organizational principles in systems neuroscience. To this date, however, it has received little philosophical analysis. This is unfortunate, because the general concept of hierarchy ranges over two approaches with distinct empirical commitments, and whose conceptual relations remain unclear. We call the first approach the “representational hierarchy” view, which posits that an anatomical hierarchy of feed-forward, feed-back, and lateral connections underlies a signal processing hierarchy of input-output relations. (...) Because the representational hierarchy view holds that unimodal sensory representations are subsequently elaborated into more categorical and rule-based ones, it is committed to an increasing degree of abstraction along the hierarchy. The second view, which we call “topological hierarchy", is not committed to different representational functions or degrees of abstraction at different levels. Topological approaches instead posit that the hierarchical level of a part of the brain depends on how central it is to the pattern of connections in the system. Based on the current evidence, we argue that three conceptual relations between the two approaches are possible: topological hierarchies could substantiate the traditional representational hierarchy, conflict with it, or contribute to a plurality of approaches needed to understand the organization of the brain. By articulating each of these possibilities, our analysis attempts to open a conceptual space in which further neuroscientific and philosophical reasoning about neural hierarchy can proceed. (shrink)

Phase I clinical trials are the first stage of testing new pharmaceuticals in humans. The majority of these studies are conducted under controlled, inpatient conditions using healthy volunteers who are paid for their participation. This article draws on an ethnographic study of six phase I clinics in the United States, including 268 semistructured interviews with research staff and healthy volunteers. In it, I argue that an institutional banalization of risk structures the perceptions of research staff and healthy volunteers participating in (...) the studies. For research staff, there are three mechanisms by which risk becomes banal: a perceived homogeneity of studies, Fordist work regimes, and data-centric discourse. For healthy volunteers, repeat study participation contributes to the institutional banalization of risk both through the process of desensitization to risk and the formation of trust in the clinics. I argue that the institutional banalization of risk also renders invisible ethical concerns about exploitation of underprivileged groups in pharmaceutical research. (shrink)

Current, prevalent models of the food system, including complex-adaptive systems theories and commodity-as-relation thinking, have usefully analyzed the food system in terms of its elements and relationships, confronting persistent questions about a system’s identity and leverage points for change. Here, inspired by Heldke’s analysis, we argue for another approach to the “system-ness” of food that carries those key questions forward. Drawing on Niklas Luhmann’s systems theory, we propose a model of the food system defined by the relational process of (...) feeding itself; that is, the food system is made of feeding and only feeding, and system structures are produced by the coupling of that process to its various contexts. We argue that this approach moves us away from understandings of the food system that take structures and relations as given, and sees them instead as contingent, thereby helping to identify leverage points for food system change. The new approach we describe also prompts us as critical agrifood scholars to be constantly reflexive about how our analyses are shaped by our own assumptions and subjectivities. (shrink)

Whilst it is generally accepted that breast-feeding lowers the likelihood of conception, this relationship is not straightforward and there appears to be a wide variation in the effectiveness of the association between individual mother-infant pairs. Up to about 6 months post-partum breast-feeding probably can be used as a family planning method, with up to 98% effectiveness if behavioural guidelines are adhered to . But beyond this time significant variations appear between different countries, and even different communities within countries, which make (...) any overall recommendation impossible. To understand the reasons for variation in the duration of lactational infecundity it is necessary to understand the mechanisms involved, but knowledge of these processes is still far from complete. There are, nevertheless, enough data to indicate that suckling and maternal milk output are intimately linked with the return of fecundity. (shrink)

The present paper reveals (non-relativistic) quantum mechanics as an emergent property of otherwise classical ergodic systems embedded in a stochastic vacuum or zero-point radiation field (zpf). This result provides a theoretical basis for understanding recent numerical experiments in which a statistical analysis of an atomic electron interacting with the zpf furnishes the quantum distribution for the ground state of the H atom. The action of the zpf on matter is essential within the present approach, but it is the ergodic demand (...) what ultimately leads to the matrix formulation of quantum mechanics. The paper thus represents a step forward in the quest for an elucidation of the fundamentals of quantum mechanics. (shrink)

Evidence-based medicine (EBM) makes use of explicit procedures for grading evidence for causal claims. Normally, these procedures categorise evidence of correlation produced by statistical trials as better evidence for a causal claim than evidence of mechanisms produced by other methods. We argue, in contrast, that evidence of mechanisms needs to be viewed as complementary to, rather than inferior to, evidence of correlation. In this paper we first set out the case for treating evidence of mechanisms alongside evidence (...) of correlation in explicit protocols for evaluating evidence. Next we provide case studies which exemplify the ways in which evidence of mechanisms complements evidence of correlation in practice. Finally, we put forward some general considerations as to how the two sorts of evidence can be more closely integrated by EBM. (shrink)

Mechanistic philosophy of science views a large part of scientific activity as engaged in modelling mechanisms. While science textbooks tend to offer qualitative models of mechanisms, there is increasing demand for models from which one can draw quantitative predictions and explanations. Casini et al. (Theoria 26(1):5–33, 2011) put forward the Recursive Bayesian Networks (RBN) formalism as well suited to this end. The RBN formalism is an extension of the standard Bayesian net formalism, an extension that allows for (...) modelling the hierarchical nature of mechanisms. Like the standard Bayesian net formalism, it models causal relationships using directed acyclic graphs. Given this appeal to acyclicity, causal cycles pose a prima facie problem for the RBN approach. This paper argues that the problem is a significant one given the ubiquity of causal cycles in mechanisms, but that the problem can be solved by combining two sorts of solution strategy in a judicious way. (shrink)

Quantum mechanics is an extraordinarily successful scientific theory. But more than 100 years after it was first introduced, the interpretation of the theory remains controversial. This Element introduces some of the most puzzling questions at the foundations of quantum mechanics and provides an up-to-date and forward-looking survey of the most prominent ways in which physicists and philosophers of physics have attempted to resolve them. Topics covered include nonlocality, contextuality, the reality of the wavefunction and the measurement problem. The discussion (...) is supplemented with descriptions of some of the most important mathematical results from recent work in quantum foundations, including Bell's theorem, the Kochen-Specker theorem and the PBR theorem. (shrink)

We consider the problem of whether there are deterministic theories describing the evolution of an individual physical system in terms of the definite trajectories of its constituent particles and which stay in the same relation to quantum mechanics as Bohmian mechanics but which differ from the latter for what concerns the trajectories followed by the particles. Obviously, one has to impose on the hypothetical alternative theory precise physical requirements. We analyze various such constraints and we show step by step how (...) to meet them. This way of attacking the problem turns out to be useful also from a pedagogical point of view since it allows one to recall and focus on some relevant features of Bohm's theory. One of the central requirements we impose on the models we are going to analyze has to do with their transformation properties under the transformation of the extended Galilei group. In a context like the one we are interested in, one can put forward various requests that we refer to as physical and genuine covariance and invariance. Other fundamental requests are that the theory allows the description of isolated physical systems as well as that it leads to a solution (in the same sense as Bohmian mechanics) of the measurement problem. We show that, even when all the above conditions are taken into account, there are infinitely many inequivalent (from the point of view of the trajectories) bohmian-like theories reproducing the predictions of quantum mechanics. This raises some interesting questions about the meaning of Bohmian mechanics. (shrink)

Dysregulation of lipid metabolism is a commonly observed feature associated with metabolic syndrome and leads to the development of negative health outcomes such as obesity, diabetes mellitus, non‐alcoholic fatty liver disease, or atherosclerosis. Time‐restricted feeding/eating (TRF/TRE), an emerging dietary intervention, has been shown to promote pleiotropic health benefits including the alteration of diurnal expression of genes associated with lipid metabolism, as well as levels of lipid species. Although TRF likely induces a response in multiple organs leading to the modulation of (...) lipid metabolism, a majority of the studies related to TRF effects on lipids have focused only on individual tissues, and furthermore there is a lack of insight into potential underlying mechanisms. In this review, we summarize the current insights regarding TRF effects on lipid metabolism and the potential mechanisms in adipose tissue, liver, skeletal muscle, and heart, and conclude by outlining possible avenues for future exploration. (shrink)

Ideas about human consciousness and mental functions will be analyzed and developed using cognitive science information available in the Upanishads, Brahmajnaana, Advaita and Dvaita schools of thought. -/- The analysis and development so done will be used to theorize and give scheme of human language acquisition and communication process clubbing with Sabdabrahma Siddhanta/Sphota Vaada which put forward infrasonic wave oscillator issuing pulses in infrasonic range and are reflected as brain waves. -/- Thus a brain-wave modulation/demodulation model of human language (...) acquisition and communication will be advanced and put forward. Application of this study in mind-machine modeling, natural language comprehension field of artificial intelligence will also be hinted. -/- . (shrink)

A decade ago, leptin (from the greek lepto meaning ‘thin’) was identified as the product of the ob gene.1 This adipocyte‐derived hormone was found to suppress feeding and stimulate thermogenesis, and was thus proposed as a mediator in a negative feedback loop that controls body adiposity. This discovery led to a rapid revolution in the understanding of neurobiological mechanisms regulating obesity. However, while leptin's first life was as an adipostat, it is now known to have a wide range of (...) additional neuroendocrine, metabolic and behavioural functions in the CNS and periphery. Remarkably, the pleiotropic nature of the hormone continues to be extended with the recent publication of two papers that expand on leptin's neurobiological actions in the CNS.2,3 They indicate novel regulatory roles for the hormone in both synaptic plasticity and axon guidance. Crucially, in light of the rising incidence of obesity in modern society, both of the studies reveal leptin‐mediated links between nutrition and neurodevelopment, findings that have further implications for leptin's role in the regulation of energy homeostasis. BioEssays 26:1043–1045, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Nineteenth-century psychiatrists ascribed to a model of health that was predicated on the existence of objective and strictly defined laws of nature. The allegedly “natural” rules governing the production of consumption of food, however, were structured by a set of distinctively bourgeois moral values that demonized over-indulgence and intemperance, encouraged self-discipline and productivity, and treated gentility as an index of social worth. Accordingly, the asylum acted not only as a therapeutic instrument but also as a moral machine that was designed (...) to remake lazy, indolent transgressors into useful, “decorous” citizens. Because the theory and mechanics underlying this machine seemed straightforward and self-evident to psychiatrists, they were confounded when the asylum failed to translate its ideals into reality. While psychiatrists tended to blame this failure on the intractable immorality and weakness of individual patients, particularly paupers and immigrants, a review of the various meanings and uses of food in the hospital reveals the fault lines that ran through the asylum’s ideological structure. (shrink)

Against the background of high demand for protein-rich feed in the EU and the environmental degradation associated with intensive livestock farming, insect-based feed is discussed as a potential sustainable alternative to conventional feed. However, the establishment of such an innovation depends not only upon technical and economic feasibility, but also on social factors impacting acceptability. The aim of this paper was to determine the acceptability of different social actor groups towards the use of insects as livestock (...) class='Hi'>feed, and to gain insights into value-based arguments leading to positive or negative attitudes and perceived benefits and risks. By means of qualitative content analysis, we analysed responses of an EU public consultation process linked to the authorization of insect protein in pig and poultry feed. We found a broad range of value-based arguments that influence the complex judgement process of acceptability that have been neglected in prior quantitative surveys. In particular, our results bring forward more critical voices, such as animal welfare concerns and scepticism that insect-based feed can contribute to a more sustainable livestock system. Based on these findings, we discuss whether insects as feed are a viable contribution to a sustainability-oriented transformation of the agri-food system. We conclude that under certain conditions (when raised on low-value organic side streams such as manure) insect-based livestock feed may contribute to incremental sustainability improvements. Overall, however, the innovation has limitations, not only in terms of regulatory conditions but especially with regard to ethical concerns. (shrink)

In our response, we review and address the comments on our target article made in the 25 commentaries. First, we review and discuss the commentaries that recognized the value of our approach, accepted the main premises and conclusions of our target article, and suggested further avenues for research on attractiveness-related biases. We then respond to commentators who either misinterpreted some parts of our target article or made statements with which we disagree. These commentaries provided us with an opportunity to clarify (...) some aspects of our target article, for example, the fact that we address both the functional significance of attractiveness-related biases and their underlying mechanisms. We provide a rebuttal to two commentaries, in which we are accused of poor scholarship. We conclude our response by addressing two commentaries that discussed the societal implications of the occurrence of attractiveness-related biases in the labor market by briefly discussing the relationship between scientific research and social policy. (shrink)

The standard view is that the Lagrangian and Hamiltonian formulations of classical mechanics are theoretically equivalent. Jill North, however, argues that they are not. In particular, she argues that the state-space of Hamiltonian mechanics has less structure than the state-space of Lagrangian mechanics. I will isolate two arguments that North puts forward for this conclusion and argue that neither yet succeeds. 1 Introduction2 Hamiltonian State-space Has less Structure than Lagrangian State-space2.1 Lagrangian state-space is metrical2.2 Hamiltonian state-space is symplectic2.3 Metric (...) > symplectic3 Hamiltonian State-space Does Not Have Less Structure than Lagrangian State-space3.1 Lagrangian state-space has less than metric structure3.1.1 A potential worry3.1.2 General Lagrangians3.2 Hamiltonian state-space has more than symplectic structure3.2.1 A dual structure on the Hamiltonian state-space3.2.2 Simple Hamiltonians3.3 Comparing Lagrangian and Hamiltonian structures3.3.1 Counting mathematical structure3.3.2 Symplectic and metric structure are incomparable4 An Alternative Argument for LS4.1 The argument for P3*4.2 Symplectic manifold vs. tangent bundle structure4.3 Trying to patch up the argument for P3*5 Interpreting Mathematical Structure5.1 State-space realism5.2 Model isomorphism and theoretical equivalence6 Conclusion. (shrink)

Early modern natural philosophers put forward the ontological program that was called "mechanical philosophy" and they gave mechanical explanations for all kinds of phenomena, such as gravity, magnetism, the colors of the rainbow, the circulation of the blood, the motion of the heart and the development of animals. For a generation of historians, the mechanical philosophy was regarded as the main alternative to Aristotelian orthodoxy during the so-called Scientific Revolution and mechanical explanations were presented as paving the way for (...) the use of experiments and mathematics in the understanding of natural phenomena. However, the historical category of mechanical philosophy was later criticized as being too broad, while early modern mechanical explanations were condemned by more epistemologically oriented minds for being incompatible with, or at least not necessarily connected to, the use of experiments and mathematics. In the last ten years, just as the new mechanistic literature emerged in philosophy of science, there has been a reevaluation of early modern mechanical explanations in a domain that had been until then considered as peripheral to the so-called Scientific Revolution, namely the domain of biology, anatomy, physiology and medicine. Although they were neither confirmed nor predictive, some early modern explanations in these domains appear to have a cognitive value similar to the value of contemporary mechanistic explanations. (shrink)

Organisms are self-producing and self-maintaining, or autopoietic systems. Therefore, the course of evolution and adaptation of an organism is strongly determined by its own internal properties, whatever role external selection may play. The internal properties may either act as constraints that preclude certain changes or they open new pathways: the organism canalizes its own evolution. As an example the evolution of feeding mechanisms in salamanders, especially in the lungless salamanders of the family Plethodontidae, is discussed. In this family a (...) large variety of different feeding mechanisms is found. The authors reconstruct this evolutionary process as a series of bifurcation points of either constraints or opportunities forming a sequence of preconditions for the formation of a high-speed projectile tongue characteristic of tropical salamanders. Furthermore, it is shown how parallel evolution of seemingly unrelated domains within an organism such as respiratory physiology, life history biology and pattern of ontogeny has rather direct relevance to the feeding biology, thus demonstrating that organisms always evolve as wholes. (shrink)

Kagan successfully forces us to re-examine our assumptions and concepts regarding the broad field of “emotion.” His postulated four phases start with the brain state provoked by some stimulus. While that constitutes a reasonable starting point, the specificity of the brain qualities provoked by different types of stimuli remains uncertain. The recommendations on the way forward are the least satisfying aspects of this article. Integration would have been helped by some consideration of the role of animal models, of the (...) ways in which genes operate, and of the multiple varieties of gene—environment interplay. (shrink)

SummaryCross-sectional studies in Australia and the Philippines and a longitudinal prospective study in a selected Australian sample of breast-feeding mothers have shown that basal serum prolactin concentrations are elevated during 15–21 months of lactational amenorrhoea.A predictive model of serum PRL levels and return of cyclic ovarian activity during full breast-feeding, partial breast-feeding and weaning has been developed from the results of breast-feeding behaviour and serum PRL, gonadotrophin and oestradiol measurements in 34 mothers breast-feeding on demand for a mean of 67 (...) weeks.Breast-feeding patterns influence serum PRL levels. Important factors during full breast-feeding are the age of the baby, the longest interval between feeds at night and total 24-hr suckling time, and following the introduction of supplements, the mean interval between feeds, together with the total 24-hr suckling time and the number of solid supplements per day.The precise mechanisms whereby breast-feeding regulates cyclic ovarian activity remain unknown. Gonadotrophin secretion appears to be quantitatively normal, but qualitative changes, secondary to altered hypothalamic activity, may be the most important factor. A direct inhibitory effect of PRL on ovarian follicular development and steroidogenesis remains possible.Ovulation with a normal luteal phase is probable for 30% of breast-feeding mothers before the first menses, but is unlikely before 6 months, provided breast-feeding is frequent day and night.Measurement of serum PRL is a sensitive index of the return of menstruation and fertility during lactation in the population studied. (shrink)