In order to make an attempt at grouping the various aspects of brain functional imaging (fMRI, MRS, EEG-MEG, ...) within a coherent frame, we implemented a model consisting of a system of differential equations, that includes: (1) sodium membrane transport, (2) Na/K ATPase, (3) neuronal energy metabolism (i.e. glycolysis, buffering effect of phosphocreatine, and mitochondrial respiration), (4) blood-brain barrier exchanges and (5) brain hemodynamics, all the processes which are involved in the activation of brain areas. We assumed that the correlation (...) between brain activation and metabolism could be due to either changes in the concentrations of ATP and ADP following activation of Na/K ATPase that result from the changes in ion concentrations, or the involvement, in different phases of metabolism, of a second messenger such as calcium. In this article, we show how this type of model enables interpretation of MRS and fMRI published data that were obtained during prolonged stimulations. (shrink)
Gliomas can display marked changes in the concentrations of energy metabolism molecules such as creatine (Cr), phosphocreatine (PCr) and lactate, as measured using magnetic resonance spectroscopy (MRS). Moreover, the BOLD (blood oxygen level dependent) contrast enhancement in functional magnetic resonance imaging (fMRI) can be reduced or missing within or near gliomas, while neural activity is not significantly reduced (so-called neurovascular decoupling), so that the location of functionally eloquent areas using fMRI can be erroneous. In this paper, we adapt a previously (...) developed model of the coupling between neural activation, energy metabolism and hemodynamics, by including the venous dilatation Balloon model of Buxton and Frank. We show that decreasing the cerebral blood flow (CBF) baseline value, or the CBF increase fraction, results in a decrease of the BOLD signal and an increase of the lactate peak during a sustained activation. Baseline lactate and PCr levels are not significantly affected by CBF baseline reduction, but are altered even by a moderate decrease of mitochondrial respiration. Decreasing the total Cr and PCr concentration reduces the BOLD signal after the initial overshoot. In conclusion, we suggest that the coupled use of BOLD fMRI and MRS could contribute to a better understanding of the neurovascular and metabolic decoupling in gliomas. (shrink)
Continuous recordings of brain electrical activity were obtained from a group of 176 patients throughout surgical procedures using general anesthesia. Artifact-free data from the 19 electrodes of the International 10/20 System were subjected to quantitative analysis of the electroencephalogram (QEEG). Induction was variously accomplished with etomidate, propofol or thiopental. Anesthesia was maintained throughout the procedures by isoflurane, desflurane or sevoflurane (N = 68), total intravenous anesthesia using propofol (N = 49), or nitrous oxide plus narcotics (N = 59). A set (...) of QEEG measures were found which reversibly displayed high heterogeneity of variance between four states as follows: (1) during induction; (2) just after loss of consciousness (LOC); (3) just before return of consciousness (ROC); (4) just after ROC. Homogeneity of variance across all agents within states was found. Topographic statistical probability images were compared between states. At LOC, power increased in all frequency bands in the power spectrum with the exception of a decrease in gamma activity, and there was a marked anteriorization of power. Additionally, a significant change occurred in hemispheric relationships, with prefrontal and frontal regions of each hemisphere becoming more closely coupled, and anterior and posterior regions on each hemisphere, as well as homologous regions between the two hemispheres, uncoupling. All of these changes reversed upon ROC. Variable resolution electromagnetic tomography (VARETA) was performed to localize salient features of power anteriorization in three dimensions. A common set of neuroanatomical regions appeared to be the locus of the most probable generators of the observed EEG changes. (shrink)
We examine the consequences of long-range effects on tumour cell migration. Our starting point are previous results of ours where we have shown that the migration patterns of glioma cells are best interpreted if one assumes attractive interactions between cells. Here we complement the cellular automaton model previously introduced by the assumption of the existence of a chemorepellent produced by the main bulk of large spheroids (in the hypoxic/necrotic areas). Visible effects due to the presence of such a substance can (...) be found in the density profiles of cells migrating out of a single spheroid as well as in the angular distribution of cells coming from two close-lying spheroids. These effects depend crucially on the diffusion speed of the chemorepellent. A comparison of the simulation results to experimental data of Werbowetski et al. allows to draw (tentative) conclusions on the existence of a chemorepellent and its properties. (shrink)
This study examined health professionals’ (HPs) experience, beliefs and attitudes towards brain death (BD) and two types of donation after circulatory death (DCD)—controlled and uncontrolled DCD. Five hundred and eighty-seven HPs likely to be involved in the process of organ procurement were interviewed in 14 hospitals with transplant programs in France, Spain and the US. Three potential donation scenarios—BD, uncontrolled DCD and controlled DCD—were presented to study subjects during individual face-to-face interviews. Our study has two main findings: (1) In the (...) context of organ procurement, HPs believe that BD is a more reliable standard for determining death than circulatory death, and (2) While the vast majority of HPs consider it morally acceptable to retrieve organs from brain-dead donors, retrieving organs from DCD patients is much more controversial. We offer the following possible explanations. DCD introduces new conditions that deviate from standard medical practice, allow procurement of organs when donors’ loss of circulatory function could be reversed, and raises questions about “death” as a unified concept. Our results suggest that, for many HPs, these concerns seem related in part to the fact that a rigorous brain examination is neither clinically performed nor legally required in DCD. Their discomfort could also come from a belief that irreversible loss of circulatory function has not been adequately demonstrated. If DCD protocols are to achieve their full potential for increasing organ supply, the sources of HPs’ discomfort must be further identified and addressed. (shrink)
It is a significant coincidence that social science tends to assume a universal human need for predictability, and also uses predictive power as the basic criterion of scientific truth. It is claimed here that man's need for predictability often is crossed by a need for uncertainty and chance. Thus it seems doubtful that the methodological canon of predictability can be anchored in the universal usefulness of social predictions. Some important cases of decision?making seem to be more concerned with the past (...) than with the future. The task of the social sciences cannot be completely separated from philosophical problems, since it is part of a continuous endeavour to clarify the image of man. (shrink)
In his well?known paper from 1954, Herbert A. Simon sets out to demonstrate that it is possible, in principle, to make public predictions within the social sciences that will be confirmed by the events. However, Simon's proof by means of the Brouwer fixed?point theorem not only rests on an illegitimate use of continuous variables, it is also founded on the questionable assumption that facts ? even on the level of possibilities ? can be established by purely mathematical means. The ?proof? (...) also appears redundant since we already know from past experience that, for instance, the confirmation of a public election prediction is possible. (shrink)
Management of the renewable natural resources in Madagascar is gradually being transferred to the local communities, particularly that of forest resources. However, these local communities are struggling to assess the consequences of management plans that they themselves must develop and implement on ecologically, economically and socially sustainable grounds. In order to highlight key aspects of different management options beforehand, we have developed MIRANA, a computer model to simulate various scenarios of management plan implementation. MIRANA differs from other simulation models by (...) not only taking into account individual practices and economic exchanges, but also by accounting for the applicable regulations. These regulations are taken into consideration by means of a multiplicity of normative structures within a spatial context. The objective of this paper is to describe the representations of institutions, norms and territories proposed by MIRANA and to discuss these representations in relation to the state of the art in the field of normative multi-agent systems. (shrink)
Herbert A. Simon's reply (Inquiry, Vol. 25, No. 3) to my criticism of his 1954 paper is not to the point. He fails to respond to some of my arguments and misconceives others. One of his misconceptions is that any mathematical deduction from empirical premises which are formulated mathematically will necessarily lead to empirically valid conclusions. This claim is particularly unwarrantable in Simon's case since his mathematical premise, the continuity of the reaction function, is empirically meaningless.
Interwoven with natural structurations and personal history, the flesh , in Merleau-Ponty's gradually-forged conception, is nourished by the combined influences of neurology, Gestalt psychology and psychoanalysis. This triple influence undergirds a recurring theme in his later writings: the mirror . "The flesh is a mirror phenomenon," Merleau-Ponty tells us. The unpublished manuscripts reveal that this famous clause refers neither directly to Husserl, nor to Wallon and Lacan, but is driven by contemporary readings of Paul Schilder and Wolfgang Metzger, who study (...) the phenomena of distanciated migrations of the body-image in vision. The mirror mingles objective body with phenomenal body, in an effective community between my lived body and its external image. It shows how the flesh lives both within and outside of itself, animated by an essential incompleteness that engages perception in a process of incorporation and, thus, hints at intercorporeity.  . (shrink)
This "open letter" examines Agnes Heller's seemingly ambivilent position on feminism, as well as her pedegogy, her reading of Plato, her "ethics of personality," and her positions on critique and on "everyday life.".
Agnes Heller conversó con la Redacción de Areté el 24 de abril de 2003, durante una visita a la Universidad Católica para dictar la Lección Inaugural del Año Académico de la Facultad de Letras y Ciencias Humanas. En la conversación estuvieron presentes los profesores Pepi Patrón, Fidel Tubino y Miguel Giusti.
One of the many themes to which Agnes Heller's philosophy returns again and again is the theme of the home of the moderns. Although not necessarily her central philosophical theme, nonetheless, it opens onto the existential and multi-dimensional nature of the human condition in modernity, which her work permanently addresses.
Agnes Arber (1879-1960) was a British botanist who was a leading plant morphologist during the first half of the 20th century. She also wrote on the history and philosophy of botany. I argue in this article that her philosophical work on form and on how the work of the mind and the eye relate to each other in morphological research are relevant to the science of today. Arber's unusual blend of interests - in botany, history, philosophy, and art - put (...) her in a unique position to examine issues of form. Even her unorthodox ideas on evolution can now be seen as fitting in well with discussions of natural selection as the predominant engine of evolutionary change. Arber's views also throw light on present work dealing with developmental plant genetics and with the study of protein form. I will further argue that her marginal position relative to institutional science, while it may have left her vulnerable to criticism, also made possible her deep philosophical reflections on morphology. (shrink)
Through a discussion of Agnès Varda's career from 1954 to 2008 that focuses particularly on La Pointe Courte (1954), L'Opéra-Mouffe (1958), The Gleaners and I (2000), and The Beaches of Agnes (2008), this article considers the connections between Varda's filmmaking and her femaleness. It proposes that two aspects of Varda's cinema—her particularly perceptive portrayal of a set of geographical locations, and her visual and verbal emphasis on female embodiment—make a feminist existential-phenomenological approach to her films particularly fruitful. Drawing both (...) directly on the work of Maurice Merleau-Ponty and on some recent film- and feminist-theoretical texts that have employed his insights, it explores haptic imagery and feminist strategy in The Gleaners and I, the materialization of space characterizing Varda's blurring of fiction and documentary, and the dialectical relationship of people with their environment often observed in her cinema. It concludes that both Varda's female protagonists and the director herself may be said to perform feminist phenomenology in her films, in their actions, movement, and relationship to space, and in the carnality of voice and vision with which Varda's own subjectivity is registered within her film-texts. (shrink)
This article focuses on images of walking in Agnès Varda's films – Cléo de 5 à 7 (1962), Sans toit ni loi (1985), and Les Plages d’Agnès (2008). The activity of walking (as urban flânerie, circular travelling or walking backwards) is central to these films, and can be seen as a corporeal practice that not only interweaves striated and smooth spaces but also offer a gender-sensitive, political contemplation on the forces of striation and smoothing as well as a (...) re-invention of space. The women in movement in Varda's films embody a transgression of stratified territories such as the image-oriented society of the spectacle in Cléo, myths of adolescence and settled living in Sans toit ni loi, or the boundaries of aging in Les Plages d'Agnès. (shrink)
A través del personaje Agnes de la novela La inmortalidad de Milán Kundera, se hace una reflexión acerca de la singularidad en el mundo contemporáneo, singularidad que se halla invadida por los imagólogos, los medios masivos de comunicación y los lugares comunes que estos fenómenos provocan. La reflexión se acercará al personaje como símbolo de una singularidad en peligro y como posibilidad estética de resistencia a través de un derrumbamiento como posibilidad singular.
By dovetailing the classical concepts of virtue, beauty, harmony and happiness with the cardinal values of modern imagination, life and freedom, Agnes Heller galvanizes modernity's anthropological reflexivity and hints at the prospect of a classicism pertinent to the present. Beyond nostalgia for an ancient past or apology for a contemporary present, her moral anthropology is approached via a dialectical elucidation of aspects of epicurean theory attuned to modernity's complexity. Under the contemporary condition of waning postmodern challenges, escalating confusion and cynicism, (...) moral anthropology's task is as one of probing modernity's destiny for a non-predatory humanism that combines the existential wisdom of ancient theory with modern values. (shrink)
Agnes Heller is one of the leading thinkers to come out of the tradition of critical theory. Her awesome intellectual range and output includes ethics, philosophical anthropology, political philosophy and a theory of modernity and its culture. Hungarian by birth, she was one of the best known dissident Marxists in central Europe in the 1960's and 1970's. Since her forced immigration she has held visiting lectureships all over the world and has been the Hannah Arendt Professor of Philosophy at the (...) New School in New York for the last twenty years. This introduction to her thought is ideal for all students of philosophy, political theory and sociology. Grumley explores Heller's early work, elaborating her relation to Lukacs and the evolution of her own version of Marxism. He examines the subsequent break with Marxism and the initial development of an alternative radical philosophy. Finally, he explains and assesses her mature reflective post-modernism, a perspective that is both sceptical and utopian, that upholds a critical humanist perspective just as it critiques contemporary democratic culture. (shrink)
This article explores the vagaries of Agnes Heller's relationship to humanism. It initially outlines a brief account of both the historical adventures of humanism and of the great debates in the middle of the 20th century that conditioned the contemporary reception of the concept of humanism. It then analyses Heller's own unique intellectual formation under the tutelage of Lukács. After briefly outlining her initial commitment to his humanist programme for the ‘Renaissance of Marxism’, it looks in more depth at her (...) initial critique of its humanist philosophical anthropology and her efforts, under the auspices of Arendt, to develop a more sophisticated account of the human condition. The analysis of Heller finally explores the impact of a postmodern awareness of contingency, fallibility and historical open-endedness on this account. The article concludes by pointing to both the commonalities and differences with the contemporary critical humanism of Tzvetan Todorov. It is argued that despite the many parallels, these differences signify Heller's final parting of the ways with humanism strictly speaking and also represent unresolved issues for any reanimation of contemporary humanism. (shrink)
The following paper explicates and critically analyses the existential ethics of the reflective postmodernist phase in the work of Agnes Heller. Beginning with a brief summary of the biographical and theoretical roots of her development, it goes on to analyse the meaning of her key slogan of ?turning contingency into destiny.? After elaborating her version of the ?existential leap? and her later attempts to refine her position in An Ethics of Personality, the paper will employ some literary lives from W. (...) G. Sebald and J. M. Coetzee to test the general viability of Heller's model. (shrink)
The article tracks the development of Agnes Heller”s political philosophy as it evolves through the Marxism and reform communism of her years as a dissent Hungarian intellectual, followed by the period of her encounters with the Western Left and with the currents of postmodern liberalism.
Professor Aubert's ?three?stage rocket? (Inquiry, Vol. 26 , No. 1) has reached periodic orbit. His comments on my earlier reply to his critique of my election predictions paper simply repeat arguments I have already refuted. In this note, I limit myself largely to pointing out Professor Aubert's misconceptions of what my position actually is. I find no reasons for revising the views stated in my original election predictions paper, nor any reasons for thinking that paper violated norms of (...) scientific method that prevail in the natural sciences. (shrink)