Oulis pointed out that there is a great deal of interest in specific mechanisms relating to mental disorders and that these mechanisms should play a role in classification. Although specific mechanisms are important, more attention should be given to general theories. The following example from Salmon illustrates the difference.

Domain-general mechanisms are evolutionarily ancient, resulting from the evolution of affective cues signaling the attainment of evolutionary goals. Explicit processing is a particularly important set of domain-general mechanisms for constructing human groups – enabling ideologies specifying future goal states and rationalizing group aims, enabling knowledge of others' reputations essential to cooperation, understanding the rights and obligations of group membership, monitoring group members, and providing appropriate punishments to those who deviate from group aims.

The mode and timing of germ-cell specification has been studied in diverse organisms, however, the molecular mechanism regulating germ-cell-fate determination remains to be elucidated. In some model organisms, maternal germ-cell determinants play a key role. In mouse embryos, some germ-line-specific gene products exist as maternal molecules and play critical roles in a pluripotential cell population at preimplantation stages. From those cells, primordial germ cells (PGCs) are specified by extracellular signaling mediated by tissue, as well as cell–cell interaction during gastrulation. (...) Thus, establishment of germ-cell lineage in mammalian embryos appears to be regulated by a multistep process, including formation and maintenance of a pluripotential cell population, as well as specification of PGCs. PGCs can be generated from pluripotential embryonic stem (ES) cells in a simple monolayer culture in which tissue interaction does not occur. This raises the possibility that ES cells, as well as, possibly, pluripotential cells in preimplantation embryos, are more closely related to the PGC precursors than pluripotential cells after implantation. BioEssays 27:136–143, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

In their 2002 seminal paper Hauser, Chomsky and Fitch hypothesize that recursion is the only human-specific and language-specific mechanism of the faculty of language. While debate focused primarily on the meaning of recursion in the hypothesis and on the human-specific and syntax-specific character of recursion, the present work focuses on the claim that recursion is language-specific. We argue that there are recursive structures in the domain of motor intentionality by way of extending John R. Searle’s (...) analysis of intentional action. We then discuss evidence from cognitive science and neuroscience supporting the claim that motor-intentional recursion is language-independent and suggest some explanatory hypotheses: linguistic recursion is embodied in sensory-motor processing; linguistic and motor-intentional recursions are distinct and mutually independent mechanisms. Finally, we propose some reflections about the epistemic status of HCF as presenting an empirically falsifiable hypothesis, and on the possibility of testing recursion in different cognitive domains. (shrink)

The vertebrate nervous system performs the most complex functions of any organ system. This feat is mediated by dedicated assemblies of neurons that must be precisely connected to one another and to peripheral tissues during embryonic development. Motor neurons, which innervate muscle and regulate autonomic functions, form an integral part of this neural circuitry. The first part of this review describes the remarkable progress in our understanding of motor neuron differentiation, which is arguably the best understood model of neuronal differentiation (...) to date. During development, the coordinate actions of inductive signals from adjacent non‐neural tissues initiate the differentiation of distinct motor neuron subclasses, with specific projection patterns, at stereotypical locations within the neural tube. Underlying this specialisation is the expression of specific homeodomain proteins, which act combinatorially to confer motor neurons with both their generic and subtype‐specific properties. Ensuring that specific motor neuron subtypes innervate the correct target structure, however, requires precise motor axon guidance mechanisms. The second half of this review focuses on how distinct motor neuron subtypes pursue highly specific projection patterns by responding differentially to spatially discrete attractive and repulsive molecular cues. The tight link between motor neuron specification and axon pathfinding appears to be established by the dominant role of homeodomain proteins in dictating the ways that navigating motor axons interpret the plethora of guidance cues impinging on growth cones. BioEssays 23:582–595, 2001. © 2001 John Wiley & Sons, Inc. (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.

In The Adapted Mind (1992), Cosmides and Tooby argue for the thesis that biological evolution endowed the human mind with a system of content‐specific computational mechanisms designed to solve long‐standing adaptive problems humans encountered as hunter‐gatherers, and not just a generalized "capacity for culture" or all‐purpose "learning capacity". I analyze three types of arguments they offer: historical arguments for the rise of content‐Specific psychology; programmatic arguments for the aims, theory, concepts, and methods of their evolutionary approach; and (...) experimental arguments for the content‐dependence of reasoning. Their arguments stand or fall on the claim that functionally specialized adaptations must be richly structured in a content‐specific way. (shrink)

Entry into mitosis is driven by the activity of kinases, which phosphorylate over 7000 proteins on multiple sites. For cells to exit mitosis and segregate their genome correctly, these phosphorylations must be removed in a specific temporal order. This raises a critical and important question: how are specific phosphorylation sites on an individual protein removed? Traditionally, the temporal order of dephosphorylation was attributed to decreasing kinase activity. However, recent evidence in human cells has identified unique patterns of dephosphorylation (...) during mammalian mitotic exit that cannot be fully explained by the loss of kinase activity. This suggests that specificity is determined in part by phosphatases. In this review, we explore how the physicochemical properties of an individual phosphosite and its surrounding amino acids can affect interactions with a phosphatase. These positive and negative interactions in turn help determine the specific pattern of dephosphorylation required for correct mitotic exit. (shrink)

Bohmian mechanics, which is also called the de Broglie-Bohm theory, the pilot-wave model, and the causal interpretation of quantum mechanics, is a version of quantum theory discovered by Louis de Broglie in 1927 and rediscovered by David Bohm in 1952. It is the simplest example of what is often called a hidden variables interpretation of quantum mechanics. In Bohmian mechanics a system of particles is described in part by its wave function, evolving, as usual, according to Schrödinger's equation. However, the (...) wave function provides only a partial description of the system. This description is completed by the specification of the actual positions of the particles. The latter evolve according to the.. (shrink)

Quantum mechanics has recently indicated that temporal order is not always fixed, a finding that has far-reaching philosophical and theological implications. The phenomena, termed “indefinite causal order,” shows that events can be in a superposition with regard to their order. In the experimental setting with which this article is concerned, two events, A and B, were shown to be in the ordering relations “A before B” and “B before A” at the same time. This article introduces an ongoing project that (...) seeks to make sense of this result, with a particular focus on the methodology by which this research will be undertaken. Specific research questions, particularly regarding what indefinite causal order might mean for the metaphysics of time and the doctrine of salvation, are introduced. The collaborative approach detailed brings together the disciplinary skills of a working scientist and a working theologian. What is offered is a collaborative methodology for interaction between science and religion that is more than the sum of its parts. Alister McGrath’s idea of multiple rationalities is employed as an epistemological framework within which this research takes place. Within an epistemologically pluralistic model, collaborative efforts are not only encouraged but necessary. Complex reality requires an equally complex, usually interdisciplinary, explanation. I argue that such dialogue is both theologically justified and culturally valuable and indicates the direction in which this research will be taken. (shrink)

The shared circuits model (SCM) relies on well-regarded theories of perception-action, mirror neurons, and forward models, but the functional/informational level of the model limits its ability to explain complex behavior such as true imitation. Data from our lab and others confirm the more general details of the model, accepted by most, but specify the neural mechanisms involved in perception-action processes.

Philosophers have studied mechanisms in many fields in biology. The focus has often been on molecular mechanisms in disciplines such as neuroscience, genetics and molecular biology, with some work on population-level mechanisms in ecology and evolution. We present a novel philosophical case study of individual-level mechanisms, mechanisms in ecology and evolution that concern the interactions between an individual and its environment. The mechanisms we analyze are called Niche Choice, Niche Conformance and Niche Construction (NC3) (...) mechanisms. Based on a detailed analysis of biologists’ research practices, we develop metaphysical claims about the components and organization of NC3 mechanisms, the phenomena they bring about and how these phenomena relate to individual differences, a major explanatory target in the field. We provide reasons for why processes of niche choice, conformance and construction are mechanisms and how they differ from molecular mechanisms underlying individual differences. Finally, we demonstrate that a general representation of NC3 mechanisms is highly abstract, with more specific types of NC3 mechanisms in particular study systems exhibiting more complex components organized in more complex ways. Our case study highlights some distinctive features of individual-level mechanisms in ecology and evolution, such as complex and heterogeneous organization and multiple phenomena. (shrink)

Ernst Mayr proposed a distinction between “proximate”, mechanistic, and “ultimate”, evolutionary, causes of biological phenomena. This dichotomy has influenced the thinking of many biologists, but it is increasingly perceived as impeding modern studies of evolutionary processes, including study of “niche construction” in which organisms alter their environments in ways supportive of their evolutionary success. Some still find value for this dichotomy in its separation of answers to “how?” versus “why?”questions about evolution. But “why is A?” questions about evolution necessarily take (...) the form “how does A occur?”, so this separation is illusory. Moreover, the dichotomy distorts our view of evolutionary causality, in that, contra Mayr, the action of natural selection, driven by genotype-phenotype-environment interactions which constitute adaptations, is no less “proximate” than the biological mechanisms which are altered by naturally selected genetic variants. Mayr’s dichotomy thus needs replacement by more realistic, mechanistic views of evolution. From a mechanistic viewpoint, there is a continuum of adaptations from those evolving as responses to unchanging environmental pressures to those evolving as the capacity for niche construction, and intermediate stages of this can be identified. Some biologists postulate an association of “phenotypic plasticity” (phenotype-environment covariation with genotype held constant) with capacity for niche construction. Both “plasticity” and niche construction comprise wide ranges of adaptive mechanisms, often fully heritable and resulting from case-specific evolution. Association of “plasticity” with niche construction is most likely to arise in systems wherein capacity for complex learning and behavioral flexibility have already evolved. (shrink)

The mechanical aspect of momentum, basically its role as a tangent vector of the trajectory of the particle, is related to properties of the momentum found in the contexts of Hamilton's optico-mechanical analogy, de Broglie's matter waves, and quantum mechanics. These properties are treated in a systematic way by considering an approximation of the particle mechanical action of the particle by a step function. A special method of discretizing partial differential equations is shown to be required. Using this method, a (...) discrete dynamics is developed. It is shown that particle dynamics can be regarded as the limit case of the discrete dynamics as the step functions tend to the continuous ones. The equation of motion of a free particle in an arbitrary reference system is deduced in two ways: (i) in continuous dynamics by making use of the invariance of action within changes of reference systems, and (ii) by taking the mentioned limit in discrete dynamics of an equation which expresses that the mechanical and wave-theoretical aspects of the momentum are interrelated in specific way. (shrink)

mechanism" is frequently encountered in the social science literature, but there is considerable confusion about the exact meaning of the term. The article begins by addressing the main conceptual issues. Use of this term is the hallmark of an approach that is critical of the explanatory deficits of correlational analysis and of the covering-law model, advocating instead the causal reconstruction of the processes that account for given macro-phenomena. The term "social mechanisms" should be used to refer to recurrent processes (...) generating a specific kind of outcome. Explanation of social macro-phenomena by mechanisms typically involves causal regression to lower-level elements, as stipulated by methodological individualism. While there exist a good many mechanism models to explain emergent effects of collective behavior, we lack a similarly systematic treatment of generative mechanisms in which institutions and specific kinds of structural configurations play the decisive role. Key Words: causal regression • correlational analysis • emergent effects • micro-macro processes • social mechanisms • structural determinants. (shrink)

Perception of temporal patterns is fundamental to normal hearing, speech, motor control, and music. Certain types of pattern understanding are unique to humans, such as musical rhythm. Although human responses to musical rhythm are universal, there is much we do not understand about how rhythm is processed in the brain. Here, I consider findings from research into basic timing mechanisms and models through to the neuroscience of rhythm and meter. A network of neural areas, including motor regions, is regularly (...) implicated in basic timing as well as processing of musical rhythm. However, fractionating the specific roles of individual areas in this network has remained a challenge. Distinctions in activity patterns appear between "automatic" and "cognitively controlled" timing processes, but the perception of musical rhythm requires features of both automatic and controlled processes. In addition, many experimental manipulations rely on participants directing their attention toward or away from certain stimulus features, and measuring corresponding differences in neural activity. Many temporal features, however, are implicitly processed whether attended to or not, making it difficult to create controlled baseline conditions for experimental comparisons. The variety of stimuli, paradigms, and definitions can further complicate comparisons across domains or methodologies. Despite these challenges, the high level of interest and multitude of methodological approaches from different cognitive domains (including music, language, and motor learning) have yielded new insights and hold promise for future progress. (shrink)

The claim that mechanisms are essential good science is widespread. I argue, however, that these claims are ambiguous in multiple ways. I sort out different version of the mechanism idea: (1) mechanisms that are horizontal —between cause and effect— and mechanisms that are vertical —they realize in lower-level terms causal properties—: and (2) different purposes or uses mechanisms may have. I then focus on the claim that various senses of mechanism are necessary for the confirmation of (...) causal claims. The paper shows that mechanisms can be useful, essential, or harmful depending on context, using the now standard graphical causal structure framework. These conclusions also support the larger philosophy of science moral that methodological norms in science are often context specific and empirical, not a priori and universal. (shrink)

How Darwin's “endless forms most beautiful” have evolved remains one of the most exciting questions in biology. The significant variety of bacterial shapes is most likely due to the specific advantages they confer with respect to the diverse environments they occupy. While our understanding of the mechanisms generating relatively simple shapes has improved tremendously in the last few years, the molecular mechanisms underlying the generation of complex shapes and the evolution of shape diversity are largely unknown. The (...) emerging field of bacterial evolutionary cell biology provides a novel strategy to answer this question in a comparative phylogenetic framework. This relatively novel approach provides hypotheses and insights into cell biological mechanisms, such as morphogenesis, and their evolution that would have been difficult to obtain by studying only model organisms. We discuss the necessary steps, challenges, and impact of integrating “evolutionary thinking” into bacterial cell biology in the genomic era. (shrink)

The notion of social mechanisms has experienced an increasing use in the social sciences as an alternative explanatory framework to the logic of co-variation present in multivariate analyses, emphasizing the causal explanation of social phenomena over their mere description. This paper seeks two goals. In the one hand, summarise recent literature on social mechanisms in order to clarify their meanings, different modes of use and their contribution to empirical research. In the other hand, we will shed some light (...) onto the relation between social mechanisms and the micro-macro problem in social sciences. We argue that the search for social mechanisms and reductionism in social sciences correspond to two interrelated but analytically distinguishable questions: while the first one seeks to define intermediary processes and causal connections between causes and effects, the second question asks for the different levels of reality in which the relation between initial conditions and effects shall be understood. Following Daniel Little´s methodological localism, we will suggest that social mechanisms can well take place at the supra-individual level, and that the reduction of social phenomena to their micro-foundations is not a methodological prescription, but rather depends on the state of art of specific fields of inquiry. La noción de mecanismos sociales ha experimentado un uso creciente en ciencias sociales. Estos se han consolidado como un marco explicativo alternativo a la lógica de co-variación propia del análisis multivariado, enfatizando además la explicación causal de los fenómenos sociales por sobre su mera descripción. Este artículo tiene dos objetivos. Primero, sistematizar la reciente literatura sobre mecanismos sociales, con el fin de clarificar sus significados, modos de uso y aporte a la investigación empírica. Y segundo, entregaremos luces a la relación entre mecanismos sociales y el problema de la relación macro-micro en ciencias sociales. Sostendremos la idea de que la búsqueda de mecanismos sociales y el reduccionismo en ciencias sociales corresponden a dos preguntas relacionadas pero analíticamente distinguibles: mientras la primera busca definir procesos intermedios y conexiones causales entre condiciones iniciales y efectos, la segunda se pregunta por los distintos niveles de la realidad en los cuales la relación entre condiciones iniciales y efectos deben ser entendidos. Siguiendo el localismo metodológico de Daniel Little, sugeriremos que los mecanismos sociales pueden bien operar a niveles supra-individuales, y que la reducción de fenómenos sociales a interacciones individuales no es una prescripción metodológica, sino que se desprende del estado del arte de campos de investigación específicos. (shrink)

The explanatory value of niche construction can be strengthened by firm footing in semiotic theory. Anthropologists have a unique perspective on the integration of such diverse approaches to human action and evolutionary processes. Here, we seek to open a dialogue between anthropology and biosemiotics. The overarching aim of this paper is to demonstrate that niche construction, including the underlying mechanism of reciprocal causation, is a semiotic process relating to biological development as well as cognitive development and cultural change. In making (...) this argument we emphasize the semiotic mechanisms underlying the niche concept. We argue that the “niche” in ecology and evolutionary biology can be consistent with the Umwelt of Jakob von Uexkull. Following John Deely we therefore suggest that investigations into the organism—environment interface constituting niche construction should emphasize the semiotic basis of experience. Peircean signs are pervasive and allow for flexible interpretations of phenomena in relation to the perceptual and cognitive capacities of the behaving organism, which is particularly pertinent for understanding the relation of proximate/ultimate selective forces as co-productive. Additionally, theoretical work by Kinji Imanishi on the evolution of daily life and Gregory Bateson’s relational view of evolution both support the linkage between proximate and ultimate evolutionary processes of causation necessitated by the niche construction perspective. We will then apply this theoretical framework to two specific examples: 1) hominin evolution, including uniquely human cultural behaviors with niche constructive implications; and 2) the multispecies and anthropocentric niche of human-dog coevolution from which complex cognitive capacities and semiotic relationships emerged. The intended outcome of this paper is the establishment of concrete semiotic mechanisms and theory underlying niche constructive behavior which can then be applied to a broad spectrum of organisms to contextualize the reciprocal relation between proximate and ultimate drivers of behavior. (shrink)

The contribution describes some aspects related to the representation of special curves; recalling mechanisms created specifically for the design of these curves, which have particular characteristics. Through the construction of a simple apparatus, consisting of two pendulums—which oscillate at the same time- it is possible to graphically reproduce Lissajous’ experiments on the commuting vibrations of the diapasons. This equipment was first built by Samuel Charles Tisley (London 1829-Unknown), under the name of harmonographer. The contribution aslo illustrates the essential characteristics (...) of the harmonograph—born as a means of analysing vibrations—but which, by its principle belongs to mechanics, for its applications to acoustic science and geometry for the ability to draw “harmonious” curves. (shrink)

Multi-stakeholder initiatives are increasingly used as a default mechanism to address human rights challenges in a variety of industries. MSI is a designation that covers a broad range of initiatives from best-practice sharing learning platforms to certification bodies and those targeted at addressing governance gaps. Critics contest the legitimacy of the private governance model offered by MSIs. The objective of this paper is to theoretically develop a typology of MSIs, and to empirically analyze the legitimacy of one specific type (...) of MSI, namely industry-specific MSIs. We argue that industry-specific MSIs that set out to govern corporate behavior have great potential to develop legitimacy. We analyze two industry-specific MSIs—the Fair Labor Association and the Global Network Initiative—to get a better understanding of how these MSIs formed, how they define and enforce standards, and how they seek to ensure accountability. Based on these empirical illustrations, we discuss the value of this specific MSI model and draw implications for the democratic legitimacy of private governance mechanisms. (shrink)

In this paper we analyze and discuss the historical and philosophical development of the notion of logical possibility focusing on its specific meaning in classical and quantum mechanics. Taking into account the logical structure of quantum theory we continue our discussion regarding the Aristotelian Square of Opposition in orthomodular structures enriched with a monadic quantifier. Finally, we provide an interpretation of the Orthomodular Square of Opposition exposing the fact that classical possibility and quantum possibility behave formally in radically different (...) manners. (shrink)

1. Living organisms are characterized by complexity and uniqueness of structure, as well as by specific pattern of changes during ontogenesis programmed in their own genome.2. Although general mechanisms of gene expression and regulation are well understood, our knowledge of spatial morphogenesis is rather limited and patchy despite discovery of homeotic genes.3. Developmental biology is able to explain principles of formation of neuronal network in the brain, whereas neurophysiology provides detailed information on the role of various neurotransmitters, but (...) we still do not understand the essence of consciousness, and even more self-consciousness of the man.4. Some philosophical theories trying to explain the nature of self-consciousness, such as parallelism and interactionism, are briefly discussed. (shrink)

Backgrounds: Transcranial direct current stimulation is a non-invasive brain stimulation technique for the treatment of several psychiatric disorders, e.g., mood disorders and schizophrenia. Therapeutic effects of tDCS are suggested to be produced by bi-directional changes in cortical activities, i.e., increased/decreased cortical excitability via anodal/cathodal stimulation. Although tDCS provides a promising approach for the treatment of psychiatric disorders, its neurobiological mechanisms remain to be explored.Objectives: To review recent findings from neurophysiological, chemical, and brain-network studies, and consider how tDCS ameliorates psychiatric (...) conditions.Findings: Enhancement of excitatory synaptic transmissions through anodal tDCS stimulation is likely to facilitate glutamate transmission and suppress gamma-aminobutyric acid transmission in the cortex. On the other hand, it positively or negatively modulates the activities of dopamine, serotonin, and acetylcholine transmissions in the central nervous system. These neural events by tDCS may change the balance between excitatory and inhibitory inputs. Specifically, multi-session tDCS is thought to promote/regulate information processing efficiency in the cerebral cortical circuit, which induces long-term potentiation by synthesizing various proteins.Conclusions: This review will help understand putative mechanisms underlying the clinical benefits of tDCS from the perspective of neurotransmitters, network dynamics, intracellular events, and related modalities of the brain function. (shrink)

A central goal of cognitive science is to develop a general theory of transfer to explain how people use and apply their prior knowledge to solve new problems. Previous work has identified multiple mechanisms of transfer including (but not limited to) analogy, knowledge compilation, and constraint violation. The central hypothesis investigated in the current work is that the particular profile of transfer processes activated for a given situation depends on both (a) the type of knowledge to be transferred and (...) how it is represented, and (b) the processing demands of the transfer task. This hypothesis was investigated in two laboratory training studies. The results from Experiment 1 show that each mechanism predicts specific behavioural patterns of performance across a common set of transfer tasks. The results from Experiment 2 show that people can adaptively shift between transfer mechanisms depending on their prior knowledge and the characteristics of the task environment. A framework for the development of a general theory of transfer based on multiple mechanisms is proposed and implications of the theory are discussed for measuring and understanding knowledge transfer. (shrink)

In this paper, I critically assess different interpretations of Bohmian mechanics that are not committed to an ontology based on the wave function being an actual physical object that inhabits configuration space. More specifically, my aim is to explore the connection between the denial of configuration space realism and another interpretive debate that is specific to Bohmian mechanics: the quantum potential versus guidance approaches. Whereas defenders of the quantum potential approach to the theory claim that Bohmian mechanics is better (...) formulated as quasi-Newtonian, via the postulation of forces proportional to acceleration; advocates of the guidance approach defend the notion that the theory is essentially first-order and incorporates some concepts akin to those of Aristotelian physics. Here I analyze whether the desideratum of an interpretation of Bohmian mechanics that is both explanatorily adequate and not committed to configuration space realism favors one of these two approaches to the theory over the other. Contrary to some recent claims in the literature, I argue that the quasi-Newtonian approach based on the idea of a quantum potential does not come out the winner. (shrink)

Are mechanisms for social attention influenced by culture? Evidence that social attention is triggered automatically by bottom-up gaze cues and is uninfluenced by top-down verbal instructions may suggest it operates in the same way everywhere. Yet considerations from evolutionary and cultural psychology suggest that specific aspects of one's cultural background may have consequence for the way mechanisms for social attention develop and operate. In more interdependent cultures, the scope of social attention may be broader, focusing on more (...) individuals and relations between those individuals. We administered a multi-gaze cueing task requiring participants to fixate a foreground face flanked by background faces and measured shifts in attention using eye tracking. For European Americans, gaze cueing did not depend on the direction of background gaze cues, suggesting foreground gaze alone drives automatic attention shifting; for East Asians, cueing patterns differed depending on whether the foreground cue matched or mismatched background cues, suggesting foreground and background gaze information were integrated. These results demonstrate that cultural background influences the social attention system by shifting it into a narrow or broad mode of operation and, importantly, provides evidence challenging the assumption that mechanisms underlying automatic social attention are necessarily rigid and impenetrable to culture. (shrink)

RESUMEN Dentro de la enorme cantidad de temas reinantes relacionados con el desarrollo científico-tecnológico actual, se encuentra indudablemente el del empleo de la ventilación mecánica no invasiva como medida de soporte vital. Aunque no se trata de una obra especifica que presente un panorama completo y exacto, de todos y cada uno de los problemas relacionados con el empleo de la misma, los autores pretenden con el artículo realizar una breve reflexión del tema desde el enfoque de la ciencia, la (...) tecnología y la sociedad en el momento actual, de manera que constituya un marco útil para el examen de estos temas, su debate, reflexión e intercambio de opiniones en el contexto de los servicios de la salud. ABSTRACT Among the huge number of current issues related to the current scientific-technological development is undoubtedly the use of non-invasive mechanical ventilation as a measure of life support. Although it is not a specific work that presents a complete and accurate picture of each one of the problems related to the use of it. Authors intend with the article to make a brief reflection on the subject from the perspective of science, technology and society at the present time, so that it constitutes a useful framework for the examination of these issues, debate, reflection and exchange of opinions in the context of health services. (shrink)

The cell theory of Schleiden and Schwann is generalized to the effect that throughout the natural world, in physics, biology, and sociopsychology, there is a widespread phenomenon of the existence of organized cells, whose organization is usually protected by barriers. These barriers exist not only in space, but in time and even in other domains. These barriers typically not only protect the organization within the cell from external disturbance, but they actively participate in reducing the internal disorganization. It appears that (...) the quantum phase cell or its equivalent, the discrete quantum state, may be a physical analog of the organized biological cell. The sampling and ambiguity theorems of communication theory throw new light on phase cells. The quantum phase cell has both configuration and momentum elements, which are analogous respectively to the somatic elements in the cytoplasm of a cell and the genetic elements in the DNA. A biological cell or organism, a physical quantum state, and a human being as a sociopsychological entity each has a natural individuality. A natural individuality is a somewhat mysterious thing, since in addition to specificity, it also involves stochasticity and complementarity. There are some striking and unexplained spin-analog characteristics in biology which have a relation to boson- and fermion-analog characteristics in biology that corresponds with the known relation in physics. The hypothesis suggested in our earlier paper, that quantum mechanical entropy is diminished in interaction, is clarified and sharpened in this paper. (shrink)

HIT produces category-specific deficits without category- specific mechanisms by assuming that differences in properties of objects are transparently converted into differences in representational format. A complete model would specify the mechanisms that accomplish this. Such category-specific mechanisms may have evolved because assumptions about the properties of some kinds of objects (e.g., living things) are invalid for others (e.g., artifacts).

In this work we study the relativistic mechanics of continuous media on a fundamental level using a manifestly covariant proper time procedure. We formulate equations of motion and continuity (and constitutive equations) that are the starting point for any calculations regarding continuous media. In the force free limit, the standard relativistic equations are regained, so that these equations can be regarded as a generalization of the standard procedure. In the case of an inviscid fluid we derive an analogue of the (...) Bernoulli equation. For irrotational flow we prove that the velocity field can be derived from a potential. If in addition, the fluid is incompressible, the potential must obey the d'Alembert equation, and thus the problem is reduced to solving the d'Alembert equation with specific boundary conditions (in both space and time). The solutions indicate the existence of light velocity sound waves in an incompressible fluid (a result known in previous literature (19) ). Relaxing the constraints and allowing the fluid to become linearly compressible one can derive a wave equation, from which the sound velocity can again be computed. For a stationary background flow, it has been demonstrated that the sound velocity attains its correct values for the incompressible and nonrelativistic limits. Finally viscosity is introduced, bulk and shear viscosity constants are defined, and we formulate equations for the motion of a viscous fluid. (shrink)

Early in animal development, gradients of secreted morphogenic molecules, such as Sonic hedgehog (Shh), Wnt and TGFβ/Bmp family members, regulate cell proliferation and determine the fate and phenotype of the target cells by activating well‐characterized signalling pathways, which ultimately control gene transcription. Shh, Wnt and TGFβ/Bmp signalling also play an important and evolutionary conserved role in neural circuit assembly. They regulate neuronal polarization, axon and dendrite development and synaptogenesis, processes that require rapid and local changes in cytoskeletal organization and plasma (...) membrane components. A key question then is whether morphogen signalling at the growth cone uses similar mechanisms and intracellular pathway components to those described for morphogen‐mediated cell specification. This review discusses recent advances towards the understanding of this problem, showing how Shh, Wnt and TGFβ/Bmp have adapted their ‘classical’ signalling pathways or adopted alternative and novel molecular mechanisms to influence different aspects of neuronal circuit formation. (shrink)

Abstract“Sign stimuli” elicit specific patterns of behavior when an organism's motivation is appropriate. In the toad, visually released prey-catching involves orienting toward the prey, approaching, fixating, and snapping. For these action patterns to be selected and released, the prey must be recognized and localized in space. Toads discriminate prey from nonprey by certain spatiotemporal stimulus features. The stimulus-response relations are mediated by innate releasing mechanisms (RMs) with recognition properties partly modifiable by experience. Striato-pretecto-tectal connectivity determines the RM's recognition (...) and localization properties, whereas medialpallio-thalamo-tectal circuitry makes the system sensitive to changes in internal state and to prior history of exposure to stimuli. RMs encode the diverse stimulus conditions referring to the same prey object through different combinations of “specialized” tectal neurons, involving cells selectively tuned to prey features. The prey-selective neurons express the outcome of information processing in functional units consisting of interconnected cells. Excitatory and inhibitory interactions among feature-sensitive tectal and pretectal neurons specify the perceptual operations involved in distinguishing the prey from its background, selecting its features, and discriminating it from predators. Other connections indicate stimulus location. The results of these analyses are transmitted by specialized neurons projecting from the tectum to bulbar/spinal motor systems, providing a sensorimotor interface. Specific combinations of such projective neurons – mediating feature- and space-related messages – form “command releasing systems” that activate corresponding motor pattern generators for appropriate prey-catching action patterns. (shrink)

Talk of mechanisms is ubiquitous in the natural sciences. Interdisciplinary fields such as biochemistry and pharmacy frequently discuss mechanisms with the assistance of diagrams. Such diagrams usually depict entities as structures or boxes and activities or interactions as arrows. While some of these arrows may indicate causal or componential relations, others may represent temporal or operational orders. Importantly, what kind of relation an arrow represents may not only vary with context but also be underdetermined by empirical data. In (...) this manuscript, we investigate how an analysis of pharmacological mechanisms in terms of producing and underlying mechanisms—as discussed in the contemporary philosophy of science—may shed light on these issues. Specifically, we shall argue that while pharmacokinetic mechanisms usually describe causal chains of production, pharmacodynamics tends to focus on mechanisms of action underlying the in vivo effects of a drug. Considering the action of thyroid gland hormones in the human body as a case study, we further demonstrate that pharmacodynamic schemes tend to incorporate entities and interactions on multiple levels. Yet, traditional pharmacodynamic schemes are sketched “flat”, i.e., non-hierarchically. We suggest that transforming flat pharmacodynamic schemes into mechanistic multi-level representations may assist in disentangling the different kinds of mechanisms and relations depicted by arrows in flat schemes. The resulting Baumkuchen model provides a powerful and practical alternative to traditional flat schemes, as it explicates the relevant mechanisms and relations more clearly. On a more general note, our discussion demonstrates how pharmacology and related disciplines may benefit from applying concepts from the new mechanist philosophy to guide the interpretation of scientific diagrams. (shrink)

Non-local phonological patterns can be difficult to analyze in the context of speech production models. Some patterns – e.g., vowel harmonies, nasal harmonies – can be readily analyzed to arise from temporal extension of articulatory gestures (i.e., spreading); such patterns can be viewed as articulatorily local. However, there are other patterns – e.g., nasal consonant harmony, laryngeal feature harmony – which cannot be analyzed as spreading; instead these patterns appear to enforce agreement between features of similar segments without affecting intervening (...) segments. Indeed, there are numerous typological differences between spreading harmonies and agreement harmonies, and this suggests that there is a mechanistic difference in the ways that spreading and agreement harmonies arise. This paper argues that in order to properly understand spreading and agreement patterns, the gestural framework of Articulatory Phonology must be enriched with respect to how targets of the vocal tract are controlled in planning and production. Specifically, it is proposed that production models should distinguish between excitatory and inhibitory articulatory gestures, and that gestures which are below a selection threshold can influence the state of the vocal tract, despite not being active. These ideas are motivated by several empirical phenomena, which include anticipatory posturing before production of a word form, and dissimilatory interactions in distractor-target response paradigms. Based on these ideas, a model is developed which provides two distinct mechanisms for the emergence of non-local phonological patterns. (shrink)

Insights into the role of sleep in the molecular mechanisms of memory consolidation may come from studies of activity-dependent synaptic plasticity, such as long-term potentiation (LTP). This commentary posits a specific contribution of sleep to LTP stabilization, in which mRNA transported to dendrites during wakefulness is translated during sleep. Brain-derived neurotrophic factor may drive the translation of newly transported and resident mRNA.

The molecular cloning of new neuroactive growth factors and their receptors has greatly enhanced our understanding of important interactions among receptors and singnaling molecules. These studies have begun to illuminate some of the mechanisms that allow for specificity in neuronal signaling. Model cell systems, such as the PC‐12 pheochromocytoma cell line, express receptors for these different neurotirophic factors, leading to comparisons of signaling pathways for these factors. Upon binding their ligands, these receptors undergo phosphorylation on tyrosine residues, which directs (...) their interaction with signaling proteins containing src homology (SH2) domains, sequences that mediate associations with tyrosine‐phosphorylated proteins. These SH2 proteins translate the tyrosine kinase activity of receptors into downstream events that result in the specific cellular response. Investigations such as these have revealed that molecular specificity in signaling pathways may arise from combinatorial diversity in interactions between receptors and key regulatory proteins. (shrink)

This article examines the epistemological views of key quantum physicists of the Copenhagen circle. The discussion begins with a presentation of their conception of measurement, indeterminacy and complementarity, and goes on to focus on their views regarding the nature of being and knowledge. The author identifies the basic areas of consensus in the Copenhagen circle as well as the disagreements and disputes that arose between its members. Three main points are argued: The fundamental epistemological consensus in the group was that (...) subject and object are inseparable; that the subject participates in the formation of images of reality, which are multiple and depend on how the subject is concretely constituted historically; the disagreements within the group did not arise with logical inevitability from the principles of quantum mechanics but largely stemmed from ideological clash in the Cold War context. Being linked to specific configurations of the subjects, knowledge is always relative; but it does not follow that knowledge is illusory or inadequate; on the contrary, it is the pretension of attaining the ultimate nature of things “in themselves” that leads to devaluation of any concrete knowledge. The world is something external, generally independent of our desires and will, but at the same time is constructed as concrete objects through the specific configuration of each concrete subject. (shrink)

Despite the miraculous progress of science—it’s practitioners continue to run into mistakes, either discrediting research unduly or making leaps of causal inference where none are warranted. In this we isolate two of the reasons for such behavior involving the misplaced understanding of the role of mechanisms and mechanistic knowledge in the establishment of cause-effect relationships. We differentiate causal knowledge into causes, effects, mechanisms, cause-effect relationships, and causal stories. Failing to understand the role of mechanisms in this picture, (...) including their absence of knowledge or incorrect specification, leads to errors of wrongly excluding cause-effect relationships or wrongly inferring their existence. We highlight the primary of causality over mechanistic knowledge and causal stories in scientific reasoning. (shrink)

This article focuses on the assessment of mechanistic relations with specific attention to medicine, where mechanistic models are widely employed. I first survey recent contributions in the philosophical literature on mechanistic causation, and then take issue with Federica Russo and Jon Williamson’s thesis that two types of evidence, probabilistic and mechanistic, are at stake in the health sciences. I argue instead that a distinction should be drawn between previously acquired knowledge of mechanisms and yet-to-be-discovered knowledge of mechanisms (...) and that both probabilistic evidence and manipulation are essential with respect to newly discovered mechanisms. (shrink)