Various techniques have attempted to localize imagery. However, early findings using single cell recordings of human receptive fields during imagery tasks have had little impact. Reports by Marg and his coworkers (1968) found no evidence for imagery in human Area 17, 18, and 19. Single cells from humans suggest later imagery-related activity in hippocampus, amygdala, entorhinal cortex, and parahippocampal gyrus.

Stem cells did not become a proper research object until the 1960 s. Yet the term and the basic mind-set—namely the conception of single undifferentiated cells, be they embryonic or adult, as the basic units responsible for a directed process of development, differentiation and increasing specialisation—were already in place at the end of the nineteenth century and then transmitted on a non-linear path in the form of tropes and diagrams. Ernst Haeckel and August Weismann played a special role in this (...) story. The first coined the term Stammzelle (stem cell), the second was the author of the first cellular stem-tree diagram. Even today, I shall argue, the understanding of stem cells, especially the popular perception, is to a large extent a Haeckelian–Weismannian one. After having demonstrated this, by analysing the terminology, in this essay I will focus on the use of cytogenetic tree diagrams between 1892 and 1925 and on the tacit understanding of stem cells that they transmit. (shrink)

We review state‐of‐the‐art computational methods for constructing, from image data, generative statistical models of cellular and nuclear shapes and the arrangement of subcellular structures and proteins within them. These automated approaches allow consistent analysis of images of cells for the purposes of learning the range of possible phenotypes, discriminating between them, and informing further investigation. Such models can also provide realistic geometry and initial protein locations to simulations in order to better understand cellular and subcellular processes. To determine the structures (...) of cellular components and how proteins and other molecules are distributed among them, the generative modeling approach described here can be coupled with high throughput imaging technology to infer and represent subcellular organization from data with few a priori assumptions. We also discuss potential improvements to these methods and future directions for research. (shrink)

The recent 2014 Nobel Prize in chemistry honored an era of discoveries and technical advancements in the field of super‐resolution microscopy. However, the applications of diffraction‐unlimited imaging in biology have a long road ahead and persistently engage scientists with new challenges. Some of the bottlenecks that restrain the dissemination of super‐resolution techniques are tangible, and include the limited performance of affinity probes and the yet not capillary diffusion of imaging setups. Likewise, super‐resolution microscopy has introduced new paradigms in (...) the design of projects that require imaging with nanometer‐resolution and in the interpretation of biological images. Besides structural or morphological characterization, super‐resolution imaging is quickly expanding towards interaction mapping, multiple target detection and live imaging. Here we review the recent progress of biologists employing super‐resolution imaging, some pitfalls, implications and new trends, with the purpose of animating the field and spurring future developments. (shrink)

The use of super‐resolution imaging techniques in cell biology has yielded a wealth of information regarding cellular elements and processes that were invisible to conventional imaging. Focusing on images obtained by stimulated emission depletion (STED) microscopy, we discuss how the new high‐resolution data influence the ways in which we use and interpret images in cell biology. Super‐resolution images have lent support to some of our current hypotheses. But, more significantly, they have revealed unexpectedly complex processes that (...) cannot be accounted for by the simpler models based on diffraction‐limited imaging. The super‐resolution imaging data challenge cell biologists to change their theoretical framework, by including, for instance, interpretations that describe multiple functions, functional errors or lack of function for cellular elements. In this context, we argue that descriptive research using super‐resolution microscopy is now as necessary as hypothesis‐driven research. (shrink)

Eukaryotic genome DNA is wrapped around core histones and forms a nucleosome structure. Together with associated proteins and RNAs, these nucleosomes are organized three‐dimensionally in the cell as chromatin. Emerging evidence demonstrates that chromatin consists of rather irregular and variable nucleosome arrangements without the regular fiber structure and that its dynamic behavior plays a critical role in regulating various genome functions. Single‐nucleosome imaging is a promising method to investigate chromatin behavior in living cells. It reveals local chromatin motion, (...) which reflects chromatin organization not observed in chemically fixed cells. The motion data is like a gold mine. Data analyses from many aspects bring us more and more information that contributes to better understanding of genome functions. In this review article, we describe imaging of single‐nucleosomes and their tracked behavior through oblique illumination microscopy. We also discuss applications of this technique, especially in elucidating nucleolar organization in living cells. (shrink)

Fluorescence microscopy is a powerful tool used in scientific and medical research, but it is inextricably linked to phototoxicity. Neglecting phototoxicity can lead to erroneous or inconclusive results. Recently, several reports have addressed this issue, but it is still underestimated by many researchers, even though it can lead to cell death. Phototoxicity can be reduced by appropriate microscopic techniques and carefully designed experiments. This review focuses on recent strategies to reduce phototoxicity in microscopic imaging of living cells and (...) tissues. We describe digital image processing and new hardware solutions. We point out new modifications of microscopy methods and hope that this review will interest microscopy hardware engineers. Our aim is to underscore the challenges and potential solutions integral to the design of microscopy systems. Simultaneously, we intend to engage biologists, offering insight into the latest technological advancements in imaging that can enhance their understanding and practice. (shrink)

L'omniprésence des images dans la société mass-médiatique est corrélative de leur évanescence et du constant renouvellement qui conditionne le processus de leur consommation. Leur omnipotence se réduit ainsi à celle de stimuli destinés à induire des comportements. Or, il convient d'autant plus de revenir d'une telle exténuation de l'image que cette dernière constitue l'une des dimensions essentielles du déploiement de la vie humaine. L'image est traditionnellement rapportée à l'activité imaginante d'un sujet. Mais, s'il est vrai que l'étoffe des hommes et (...) des choses qui se donnent à voir dans le paraître sensible d'une image n'existe pas coupée d'un tel paraître, l'esthétique relève aussi de l'ontologie et sa tâche est de nous ré-apprendre à contempler les images. Au regard de la clarté et de la distinction conférées par la théorie à notre appréhension des choses, la détermination positive des images ne tient-elle pas en effet au fait que c'est dans leur dimension qu'il nous est donné de faire l'expérience vive du paraître de ces choses, jusqu'à l'extrême de l'horreur, du merveilleux et du sacré? (shrink)

Collective migration is a key process that is critical during development, as well as in physiological and pathophysiological processes including tissue repair, wound healing and cancer. Studies in genetic model organisms have made important contributions to our current understanding of the mechanisms that shape cells into different tissues during morphogenesis. Recent advances in high‐resolution and live‐cell‐imaging techniques provided new insights into the social behavior of cells based on careful visual observations within the context of a living tissue. In (...) this review, we will compare Drosophila testis nascent myotube migration with established in vivo model systems, elucidate similarities, new features and principles in collective cell migration. (shrink)

We are essentially a society of cells that come from a single cell, the fertilised egg. Research in cell biology has made major advances that are relevant to medicine and our understanding of life. Our understanding of the role of genes and proteins is impressive. But is this science dangerous? The whole of Western literature has not been kind to cell scientists and is filled with images of scientists meddling with nature, with disastrous results.1 Just consider Shelley’s (...) Frankenstein, Goethe’s Faust and Huxley’s Brave New World. One will search with very little success for a novel in which scientists come out well—the persistent image is that of scientists as a group unconcerned with ethical issues.There is a fear and distrust of cell science, particularly genetic engineering, leading to genetically modified foods, genetic modification of humans, cloning and stem cells. There is something of a revulsion in humankind’s meddling with nature and a longing for a Rousseauish-like return to golden age of innocence. There is anxiety that scientists lack both wisdom and social responsibility and are so motivated by ambition that they will follow their research anywhere, no matter what the consequences. Scientists are repeatedly referred to as “playing God”. Many of these criticisms coexist with the hope, particularly in medicine, that science will provide cures to all major illnesses, such as cancer, heart disease and genetic disabilities such as cystic fibrosis. But is cell science dangerous and what are the special social responsibilities of scientists? It is worth noting one irony: although scientists are blamed for making us live in a high-risk society, it is only because of science that we know about these risks, such as those related to health.The media must bear much of the responsibility for the misunderstanding of genetics as genetic pornography is, …. (shrink)

Morphogenesis is one of the fundamental processes of developing life. Gastrulation, especially, marks a period of major translocations and bustling rearrangements of cells that give rise to the three germ layers. It was also one of the earliest fields in biology where cell movement and behaviour in living specimens were investigated. This article examines scientific attempts to understand gastrulation from the point of view of cells in motion. It argues that the study of morphogenesis in the twentieth century faced (...) a major dilemma, both epistemological and pictorial: representing form and understanding movement are mutually exclusive, as are understanding form and representing movement. The article follows various ways of modelling, imaging, and simulating gastrular processes, from the early twentieth century to present-day systems biology. The first section examines the tactile modelling of shape changes, the second cell cinematography, mainly the pioneering work of the German embryologists Friedrich Kopsch and Ernst Ludwig Gräper in the 1920s but also a series of classic, yet not widely known, studies of the 1960s. The third section deals with the changes that computer simulation and live-cell imaging introduced to the modelling of shape change and the study of cell movement at the turn of the twenty-first century. Although live-cell imaging promises to experiment upon and represent the living body simultaneously, I argue that the new visuals are an obstacle rather than a solution to the puzzle of understanding cell motion. (shrink)

Ontology is one strategy for promoting interoperability of heterogeneous data through consistent tagging. An ontology is a controlled structured vocabulary consisting of general terms (such as “cell” or “image” or “tissue” or “microscope”) that form the basis for such tagging. These terms are designed to represent the types of entities in the domain of reality that the ontology has been devised to capture; the terms are provided with logical defi nitions thereby also supporting reasoning over the tagged data. Aim: (...) This paper provides a survey of the biomedical imaging ontologies that have been developed thus far. It outlines the challenges, particularly faced by ontologies in the fields of histopathological imaging and image analysis, and suggests a strategy for addressing these challenges in the example domain of quantitative histopathology imaging. The ultimate goal is to support the multiscale understanding of disease that comes from using interoperable ontologies to integrate imaging data with clinical and genomics data. (shrink)

Molecular interactions are at the origin of life. How molecules get at different locations in the cell and how they locate their partners is a major and partially unresolved question in biology that is paramount to signaling. Spatio‐temporal correlations of fluctuating fluorescently tagged molecules reveal how they move, interact, and bind in the different cellular compartments. Methods based on fluctuations represent a remarkable technical advancement in biological imaging. Here we discuss image analysis methods based on spatial and temporal (...) correlation of fluctuations, raster image correlation spectroscopy, number and brightness, and spatial cross‐correlations that give us information about how individual molecules move in cells and interact with partners at the single molecule level. These methods can be implemented with a standard laser scanning microscope and produce a cellular level spatio‐temporal map of molecular interactions. (shrink)

While philosophers have, for centuries, pondered upon the relation between mind and brain, neuroscientists have only recently been able to explore the connection analytically — to peer inside the black box. This ability stems from recent advances in technology and emerging neuroimaging modalities. It is now possible not only to produce remarkably detailed images of the brain’s structure (i.e. anatomical imaging) but also to capture images of the physiology associated with mental processes (i.e. functional imaging). We are able (...) to see how specific regions of the brain ‘light up’ when activities such as reading this book are performed, and how our neurons and their elaborate cast of supporting cells organize and coordinate their tasks. As demonstrated in the other chapters of this book, the mapping of the human mind (mostly by measuring regional changes in blood flow, initially by positron emission tomography (PET) and recently by functional magnetic resonance imaging or (fMRI)) has provided insight into the functional neuroanatomy of neuropsychiatric diseases. Amazingly, the idea that regional cerebral blood flow (rCBF) is related intimately to brain function goes back more than a century. As is often the case in science, this idea was initially the result of unexpected observations. The Italian physiologist Angelo Mosso first expressed the idea while studying pulsations of the living human brain that keep pace with the heartbeat (Mosso, 1881). These brain pulsations can be observed on the surface of the fontanelles in newborn children. Mosso believed that they reflected blood flow to the brain. He observed similar pulsations in an adult with a post-traumatic skull defect over the frontal lobes. While studying this subject, a peasant named Bertino, Mosso observed a sudden increase in the magnitude of the ‘brain’s heart-beats’ when the church bells signalled 12 o’clock, the time for a required prayer. The changes in brain pulsations occurred independently of any change in pulsations in the forearm.. (shrink)

We prove that forp-optimal fields a cell decomposition theorem follows from methods going back to Denef’s paper [7]. We derive from it the existence of definable Skolem functions and strongp-minimality. Then we turn to stronglyp-minimal fields satisfying the Extreme Value Property—a property which in particular holds in fields which are elementarily equivalent to ap-adic one. For such fieldsK, we prove that every definable subset ofK×Kdwhose fibers overKare inverse images by the valuation of subsets of the value group is semialgebraic. (...) Combining the two we get a preparation theorem for definable functions onp-optimal fields satisfying the Extreme Value Property, from which it follows that infinite sets definable over such fields are in definable bijection iff they have the same dimension. (shrink)

This chapter contains section titled: Utilitarian and Kantian Advice about Enhancement Moral Images and Moral Consistency Midgley's Scepticism about Consistency Harvesting Stem Cells: Research or Therapy? Are Enhancement Technologies wrong because they are ‘Yucky’? Why Food is Different Are Enhancement Technologies Wrong because they will Destroy Meaning?

Here, a streamlined, scalable, laboratory approach is discussed that enables medium‐to‐large dataset analysis. The presented approach combines data management, artificial intelligence, containerization, cluster orchestration, and quality control in a unified analytic pipeline. The unique combination of these individual building blocks creates a new and powerful analysis approach that can readily be applied to medium‐to‐large datasets by researchers to accelerate the pace of research. The proposed framework is applied to a project that counts the number of plasmonic nanoparticles bound to peripheral (...) blood mononuclear cells in dark‐field microscopy images. By using the techniques presented in this article, the images are automatically processed overnight, without user interaction, streamlining the path from experiment to conclusions. (shrink)

Fluorescence microscopy is the primary tool for studying complex processes inside individual living cells. Technical advances in both molecular biology and microscopy have made it possible to image cells from many genetic and environmental backgrounds. These images contain a vast amount of information, which is often hidden behind various sources of noise, convoluted with other information and stochastic in nature. Accessing the desired biological information therefore requires new tools of computational image analysis and modeling. Here, we review some of the (...) recent advances in computational analysis of images obtained from fluorescence microscopy, focusing on bacterial systems. We emphasize techniques that are readily available to molecular and cell biologists but also point out examples where problem‐specific image analyses are necessary. Thus, image analysis is not only a toolkit to be applied to new images but also an integral part of the design and implementation of a microscopy experiment. (shrink)

In many scientific fields, today’s practices of empirical enquiry rely heavily on the production of images that display the investigated phenomena. And while scientific images of phenomena have been important for a long time, what is striking now is that scientists have found ways to visualize such widely different types of phenomena. In the past twenty or thirty years, we have become accustomed to seeing images of galaxies, of cells, of the human brain but also of blood flow or of (...) turbulent fluids. This success in making images relies first on the set of imaging devices that have flourished in the twentieth century, instruments such as radio-telescopes, electronic microscopes, MRI and many more. Without these... (shrink)

C’est selon la perspective de l’image comme représentation que nous examinons et mettons en parallèle les œuvres de Marcel Duchamp et de Francis Bacon. Duchamp s’extirpe de l’univers de la peinture, émancipe l’art de son champ exclusivement pictural, « rétinien ». Bacon emprunte une voie intermédiaire : celle de la « forme sensible », de la « Figure », c’est-à-dire du « figural ». Qu’il s’agisse de la déformation avec Bacon ou de la transformation avec Duchamp, la représentation n’est telle (...) que parce qu’elle témoigne d’un quelque chose, irreprésentable ou imprésentable, qui l’excède : l’événement de la Figure se nomme ainsi dé-figure et trans-figure. (shrink)

Même si toute l'expression humaine ne saurait se réduire à l'esthétique littéraire et cinématographique, celle-ci n'en occupe pas moins une place importante dans ce qui révèle le sentiment de l'homme dans son adhésion à l'existence, aussi élaboré soit le cri qu'explicite et déploie cette expression. Liées à des moments de l'histoire, ces formes d'expression les expriment en même temps qu'elles s'en distancient, disant, de façon originale en chaque oeuvre ou en chaque courant, cette résistance de l'humanité à ce qui normalement (...) devrait l'anéantir. De la Shoah aux images de violence dans la cinématographie contemporaine, le témoignage de l'expression et de la résistance interroge le théologien.Even if all expression cannot be reduced to a literary and cinematographic esthetic, the latter does not occupy a place of lesser importance in that which reveals the sentiment of man in his adhesion to existence, however elaborated the cry may be that makes explicit and spreads about this expression. Tied to moments of history, these forms of expression manifest them at the same time that they take a distance from them, depicting,in an original way in each work or in each current, this resistance of humanity to that which normally should destroy it. From the Shoah to the images of violence in contemporaneous film, the witness of the expression and of the resistance questions the theologian. (shrink)

Après avoir présenté l'anthropologie philosophique de Wilhelm von Humboldt, il nous a paru éclairant, pour enrichir la compréhension de sa pensée, de la mettre en perspective avec les diverses études qui lui ont été consacrées, dans le but de capter ainsi l'image qu'il a laissée dans la postérité, tant philosophique que linguistique. On rencontre ainsi de grands noms de ces deux disciplines, notamment Cassirer et Heidegger d'une part, Chomsky et Whorf de l'autre, qui nous donnent à penser que, pour atteindre (...) en sa vérité une pensée aussi complexe, il faut quitter la plaine du commentaire et s'élever à une certaine hauteur de pensée. Se comprend ainsi alors que Humboldt ait pu être à la fois méconnu par les plus nombreux, mais reconnu par les plus grands. L'image, au terme du parcours, se révèle multiple. Ses reflets diversifiés sont la projection éclatée d'un projet fondamental, celui d'une anthropologie qui trouve son parachèvement dans le Kawi-Werk, l'oeuvre dernière. Dans celle-ci se déploie cette idée directrice que le langage est le foyer unifiant de la théorie et de la culture de l'homme, idée qui permet d'éclairer enfin la seule question qui vaille : Qu'est-ce que l'homme?"--Page 4 of cover. (shrink)

« Comme toute grande philosophie, celle de Deleuze avant Guattari et avec Guattari renouvelle la définition de la pensée. Depuis Différence et répétition, la pensée n’est pour Deleuze ni naturelle ni spontanée, elle est le produit d’une genèse : Deleuze part d’une critique de l’image représentative de la pensée qui lui permet de dégager le vrai commencement de la pensée, ses conditions réelles. Avec cette genèse, grâce à laquelle la pensée se cherche un sol autre que la représentation en renonçant (...) en même temps à tout fondement, Deleuze résout, pour son propre compte, le problème du commencement en philosophie, en faisant surgir une pensée sans image. Par la suite, Deleuze et Guattari construisent ensemble une nouvelle métaphysique qui semble se passer, en apparence seulement, des notions d’image de la pensée et de pensée sans image. En réalité, à l’unique « Image de la pensée » qu’il s’agissait de détruire dans Différence et répétition, Deleuze et Guattari substituent, dès Mille plateaux, une pluralité d’images de la pensée, chacune étant historiquement et singulièrement déterminée. Ils esquissent même dans cet ouvrage l’idée d’une « noologie » qu’ils prendraient pour objet d’étude. Ces images deviendront les plans d’immanence de Qu’est-ce que la philosophie?. Quant à la pensée sans image, nous montrerons que, loin de disparaître, elle prend différentes formes, notamment celle du chaos, dans leur dernier ouvrage. Notre hypothèse est donc que, sous des vocables changeants, ces deux idées, comme leur relation mise à jour par Deleuze, ne disparaissent pas de leur métaphysique commune. ». (shrink)

If we assume that consciousness is a natural biological phenomenon in the brain, should we expect the current brain sensing and imaging methods to somehow ‘discover’ consciousness? The answer depends on the following points: What kind of level of biological organization do we assume consciousness to be? What would count as the discovery of this level? What are the levels of organization from which the currently available research instruments pick signals and acquire data? Single-cell recordings, PET, fMRI, EEG (...) and MEG pick different types of signals from different levels of organization in the brain. However, it seems they do not manage to pick signals that would allow the direct visualization and reconstruction of the higher levels of electrophysiological organization that are crucial for the empirical discovery and theoretical explanation of consciousness. The message of the present paper is twofold: On the one hand, we should be aware of the practical limitations of the currently available methods of cognitive neuroscience and not read too much into the images produced by them. On the other hand, the present limitations could be overcome by more sophisticated methods in the future. Therefore, contrary to what several philosophers have argued, the empirical discovery of consciousness in the brain is not impossible in principle. (shrink)

This chapter contains section titled: The Biotechnological Solution to Disease Who Benefits from Gene Therapy? Are we Essentially Human Beings or Essentially Persons, and does it Matter? Genetic Influences, Environmental Influences and the Formation of Human Identities Interactionism's Implications for Identity The Scope of Therapy and the Notion of Disease Buchanan, Brock, Daniels and Wikler on Protecting Normal Functioning Therapy, Obligation and Procreative Liberty's Diminishment.

This essay details a historical crossroad in biochemistry and microbiology in which penicillin was a co-agent. I narrate the trajectory of the bacterial cell wall as the precise target for antibiotic action. As a strategic object of research, the bacterial cell wall remained at the core of experimental practices, scientific narratives and research funding appeals throughout the antibiotic era. The research laboratory was dedicated to the search for new antibiotics while remaining the site at which the mode of (...) action of this new substance was investigated. This combination of circumstances made the bacterial wall an ontology in transit. As invisible as the bacterial wall was for clinical purposes, in the biological laboratory, cellular meaning in regard to the action of penicillin made the bacterial wall visible within both microbiology and biochemistry. As a border to be crossed, some components of the bacterial cell wall and the biochemical destruction produced by penicillin became known during the 1950s and 1960s. The cell wall was constructed piece by piece in a transatlantic circulation of methods, names, and images of the shape of the wall itself. From 1955 onwards, microbiologists and biochemists mobilized new names and associated conceptual meanings. The composition of this thin and rigid layer would account for its shape, growth and destruction. This paper presents a history of biochemical morphology: a chemistry of shape – the shape of bacteria, as provided by its wall – that accounted for biology, for life itself. While penicillin was being established as an industrially-manufactured object, it remained a scientific tool within the research laboratory, contributing to the circulation of further scientific objects. (shrink)

Ce livre traite de l'image, mais aussi, plus generalement, de la copie, du double, de la representation, du calque, du sosie... La philosophie, a juste titre, a mis en garde contres ces si dangereux reflets. Ne doit-on pas preferer ce qui est a ce qui l'imite ou le mime? Mefions-nous des leurres! Cependant, on est revenu sur cette seculaire et injuste condamnation. La technologie moderne a peu a peu sauve celle qu'on avait trop inferiorisee et eloignee. Et quelle victoire! L'image (...) numerique, donc celle de synthese, l'arrache a une servitude que les philosophes classiques et meme plus modernes avaient scellee. L'electro-optique, la tomodensitometrie (scannographie), l'holographie, entre autres, multiplient les prouesses liberatrices. Dans le passe, la photographie, voire la radiographie avaient deja ebranle les anciennes positions. La guerre commencait. L'imagerie deferle donc, ainsi que l'industrie noire des contrefacons, des plagiats, des pseudo-repliques, du pastiche. Les trucages et la fraude. Mais ou situer aujourd'hui le vrai et le faux? Comment distinguer le modele et son equivalent? Les vieilles frontieres, comme on le montrera, s'estompent. Quel branle-bas et quelle fete aussi! On a voulu prendre acte de cette nouveaute. Hatons-nous, malgre le danger de nous y perdre, d'engager la philosophie que nous croyons reticente dans ce tourbillon. (shrink)

Nous vivons le temps des images, et c'est accroître ses plaisirs que de s'en donner l'intelligence. En relatant comment il a lui-même appris à ouvrir les yeux, dans les grottes ornées comme dans nos salles de musée, l'auteur, idolâtre heureux et qui ne se repent pas, entend contribuer au bon usage du "stupéfiant image". Mais l'énigme qu'il interroge tout au long de ce recueil de témoignages et de réflexions, c'est celle du temps immobile. Il est des images fixes que l'on (...) peut dater par leur style ou leur technique, mais dont nous demeurons étonnamment contemporains. Les archives visuelles des civilisations éteintes restent vivantes en sorte qu'elles auraient bien tort de se croire mortelles. Les dieux et les idées meurent, non leurs statues ni leurs figures. Et les félins de la grotte Chauvet, 35 000 ans, n'ont pas d'âge, pas plus que nos plus belles photos de stars. (shrink)

Résumé Beaucoup de cinéastes et de théoriciens français ont très longtemps clamé que le cinéma ne consistait pas à produire des images, mais des plans – catégorie adossée à la notion de durée et très vague, puisqu’elle désigne une découpe à la fois spatiale et temporelle. Cette réticence au concept d’image a ainsi nourri une sorte de « Yalta » cinéphile, distinguant la lignée des frères Lumière (la vue comme art du réel) et celle de Georges Méliès (le tableau fantasmagorique). (...) Cette opposition entre image (souvent assimilée, ici, à l’imagerie ou au cliché) et plan-durée peut être comparée à la fort ancienne querelle du dessin et de la couleur (ce qui cerne et ce qui déborde). Nous tenterons ici d’étudier l’éventualité d’un « icono-réalisme », en nous appuyant notamment sur les travaux de Gilles Deleuze et de Jacques Rancière (La Fable cinématographique), ainsi que sur un moyen-métrage de Pier Paolo Pasolini, La Ricotta (1963). (shrink)

The discovery and engineering of novel fluorescent proteins (FPs) from diverse organisms is yielding fluorophores with exceptional characteristics for live‐cell imaging. In particular, the development of FPs for fluorescence (or Förster) resonance energy transfer (FRET) microscopy is providing important tools for monitoring dynamic protein interactions inside living cells. The increased interest in FRET microscopy has driven the development of many different methods to measure FRET. However, the interpretation of FRET measurements is complicated by several factors including the high (...) fluorescence background, the potential for photoconversion artifacts and the relatively low dynamic range afforded by this technique. Here, we describe the advantages and disadvantages of four methods commonly used in FRET microscopy. We then discuss the selection of FPs for the different FRET methods, identifying the most useful FP candidates for FRET microscopy. The recent success in expanding the FP color palette offers the opportunity to explore new FRET pairs. (shrink)

Adult stem cell populations must coordinate their own maintenance with the generation of differentiated cell types to sustain organ physiology, in a spatially controlled manner and over long periods. Quantitative analyses of clonal dynamics have revealed that, in epithelia, homeostasis is achieved at the population rather than at the single stem cell level, suggesting that feedback mechanisms coordinate stem cell maintenance and progeny generation. In the central nervous system, however, little is known of the possible community (...) processes underlying neural stem cell maintenance. Recent work, in part based on intravital imaging made possible in the adult zebrafish, conclusively highlights that homeostasis in neural stem cell pools may rely on population asymmetry and long‐term spatiotemporal coordination of neural stem cell states and fates. These results suggest that neural stem cell assemblies in the vertebrate brain behave as self‐organized systems, such that the stem cells themselves generate their own intrinsic niche. (shrink)

Segmentation of the medical image plays a significant role when it comes to diagnosis using computer aided system. This article focuses on the human corneal endothelium’s health, which is one of the filed research interests, especially in the human cornea. Various pathological environments fasten the extermination of the endothelial cells, which in turn decreases the cell density in an abnormal manner. Dead cells worsen the hexagonal design. The mutilated endothelial cells can no longer revive back and that gives room (...) for neighbouring cells to migrate and expand so that they can fill in the space. The latter results in cell elongation that is unpredictable as well as increase in size and thinning. Cell density and shape are therefore considered major parameters when it comes to explaining the health condition attributed to corneal endothelium. In this study, medical feature extraction was obtained depending on the segmentation of the endothelial cell boundary, and the task of segmentation of such objects especially the thin, transparent, and unclear cell boundary is considered challenging due to the nature of the image capture during endothelium layer examination by ophthalmologists using confocal or specular microscopy. The resulting image suffers from various issues that affect the quality of the image. Low quality is due to non-uniformity of illumination and the presence of a lot of noise and artefacts resulting from high amounts of distortion, and most of these limitations are present because of the nature of the imaging modality. Usually, images contain certain kind of noise and also continuous shadow. Furthermore, the cells are separated by poor border, thereby leading to great difficulty in the segmentation of the images. The irregular shape of cell and also the contrast of such images seem to be low as they possess blurry boundaries with diverse objects existing in addition to the lack of homogeneity. The main aim of the study is to propose and develop a totally automatic, robust, and real-time model for the segmentation of endothelial cells of the human cornea obtained by in vivo microscopy and computation of different clinical features of endothelial cells. To achieve the aim of this study a new scheme of image enhancement was proposed such as the Contrast-Limited Adaptive Histogram Equalisation technique to enhance contrast. After that, a new image denoising technique called Wavelet Transform Filter and Butterworth Bandpass for Segmentation is used. Subsequently, brightness level correction is applied by using the moving average filter and the CLAHE to reduce the effects of the non-uniform image lighting produced as a result of the previous step. The main aim of this article is the segmentation of endothelial cells, which involves precise detection of the endothelial contours. So a new segmentation model was proposed such that the shape of the cells will be extracted, and the contours were highlighted. This stage is followed by clinical feature extraction and uses the features for diagnosis. In this stage, several relevant clinical features such as pleomorphism mean cell perimeter, mean cell density, mean cell area, and polymegathism are extracted. The role of these clinical features is crucial for the early detection of corneal pathologies as well as the evaluation of the health of the corneal endothelium layer. The findings of this study were promising. (shrink)

Soft X‐ray tomography (SXT) is an imaging technique capable of characterizing and quantifying the structural phenotype of cells. In particular, SXT is used to visualize the internal architecture of fully hydrated, intact eukaryotic and prokaryotic cells at high spatial resolution (50 nm or better). Image contrast in SXT is derived from the biochemical composition of the cell, and obtained without the need to use potentially damaging contrast‐enhancing agents, such as heavy metals. The cells are simply cryopreserved prior to (...) imaging, and are therefore imaged in a near‐native state. As a complement to structural imaging by SXT, the same specimen can now be imaged by correlated cryo‐light microscopy. By combining data from these two modalities specific molecules can be localized directly within the framework of a high‐resolution, three‐dimensional reconstruction of the cell. This combination of data types allows sophisticated analyses to be carried out on the impact of environmental and/or genetic factors on cell phenotypes. (shrink)

Second harmonic generating (SHG) nanoprobes have recently emerged as versatile and durable labels suitable for in vivo imaging, circumventing many of the inherent drawbacks encountered with classical fluorescent probes. Since their nanocrystalline structure lacks a central point of symmetry, they are capable of generating second harmonic signal under intense illumination – converting two photons into one photon of half the incident wavelength – and can be detected by conventional two‐photon microscopy. Because the optical signal of SHG nanoprobes is based (...) on scattering, rather than absorption as in the case of fluorescent probes, they neither bleach nor blink, and the signal does not saturate with increasing illumination intensity. When SHG nanoprobes are used to image live tissue, the SHG signal can be detected with little background signal, and they are physiologically inert, showing excellent long‐term photostability. Because of their photophysical properties, SHG nanoprobes provide unique advantages for molecular imaging of living cells and tissues with unmatched sensitivity and temporal resolution. (shrink)

Cognition or higher brain activity is sometimes seen as a phenomenon greater than the sum of its parts. This viewpoint however is largely dependent on the state of the art of experimental techniques that endeavor to characterize morphology and its association to function. Retinal ganglion cells are readily accessible for this work and we discuss recent advances in computational techniques in identifying novel parameters that describe structural attributes possibly associated with specific function. These parameters are based on calculating wavelet gradients (...) from cell images followed by the extraction of meaningful measures including 2nd wavelet moment, entropy of orientation, and curvature. For the three cell types analyzed, the mean 2nd wavelet moment, which relates to the field of influence of the dendritic-tree segments was significantly different. cells had the highest mean 2nd wavelet moment, followed by the and cells (134 ± 22, 93 ± 19 and 63 ± 12, respectively). There was no significant difference between cells for entropy of orientation, indicating no class with a preferential orientation of their dendritic tree. Curvature provided similar results to the 2nd wavelet moment with cells having the highest curvature followed by and the cells (mean ± SD: 161 ± 15; 134 ± 22; 121 ± 15). Our feature space analysis also indicated a difference between these cell types. No difference was found between the and cell types and their physiological counterparts the Y and X cells based on wavelet analysis. Both the X and Y cells can be divided into two subtypes, the ON- and OFF-center cells based on the stratification level of the dendritic tree within the retina. Using 2nd wavelet moment, a difference in their morphological attributes, not reported previously, was noted for these subtypes. The 2nd wavelet moment and curvature are further discussed with respect to explaining regularity of spacing and coverage associated with retinal ganglion cell mosaics. (shrink)

The medium surrounding cells either in culture or in tissues contains a chemical mix varying with cell state. As solutes move in and out of the cytoplasmic compartment they set up characteristic signatures in the cellular boundary layers. These layers are complex physical and chemical environments the profiles of which reflect cell physiology and provide conduits for intercellular messaging. Here we review some of the most relevant characteristics of the extracellular/intercellular space. Our initial focus is primarily on cultured (...) cells but we extend our consideration to the far more complex environment of tissues, and discuss how chemical signatures in the boundary layer can or may affect cell function. Critical to the entire essay are the methods used, or being developed, to monitor chemical profiles in the boundary layers. We review recent developments in ultramicro electrochemical sensors and tailored optical reporters suitable for the task in hand. (shrink)

La série Doctor Who est parvenue, en cinquante ans d’existence, à mettre en place une mythologie dans laquelle technologie et mythes des origines ont donné vie à un univers que la majorité des personnages perçoit comme étant « magique ». Tout comme le magicien ou la figure du sage dans le monomythe campbellien, le Docteur apparaît toujours au bon moment et provoque l’appel de l’aventure qui guide ses compagnons humains dans un monde merveilleux. Offrant souvent des explications pseudo-scientifiques incompréhensibles pour (...) le commun des mortels, le Docteur ressemble ainsi au magicien d’Oz dont les pouvoirs magiques viennent d’une maîtrise scientifique supérieure à celle de ses interlocuteurs. Mais la représentation de ce magicien spatio-temporel a pris une toute nouvelle tournure lorsqu’il est devenu évident que le Docteur et Merlin avaient une histoire et des origines communes. In fifty years, Doctor Who managed to develop a mythology in which technology and origin myths gave birth to a universe that most characters perceive as “magical”. Just like the wizard or the wise in the Campbellian monomyth, the Doctor systematically appears at the right moment and provokes the call to adventure that will lead his human companions in a wonderful world. His pseudo-scientific explanations, often incomprehensible for us mortals, thus create a certain connection between the Doctor and the Wizard of Oz, whose magic powers result from a superior knowledge of science. But the representation of this spatiotemporal magician became quite different when the Doctor and Merlin started to have a common history and a same origin. (shrink)

A fundamental question in visual neuroscience is: Why are the response properties of visual neurons as they are? A modern approach to this problem emphasizes the importance of adaptation to ecologically valid input, and it proceeds by modeling statistical regularities in ecologically valid visual input (natural images). A seminal model was linear sparse coding, which is equivalent to independent component analysis (ICA), and provided a very good description of the receptive fields of simple cells. Further models based on modeling residual (...) dependencies of the ‘‘independent” components have later been introduced. These models lead to emergence of further properties of visual neurons: the complex cell receptive fields, the spatial organization of the cells, and some surround suppression and Gestalt effects. So far, these models have concentrated on the response properties of neurons, but they hold great potential to model various forms of inference and learning. (shrink)

Hippocampal neurogenesis has been implicated in the pathogenesis of and recovery from depression. However, most of the underlying studies were endpoint investigations in experimental animals yielding conflicting results, and it has been under debate to which extent these results could be transferred to human patients. Now, researchers have developed a powerful new tool to address these questions by a non‐invasive method in humans and animals in vivo, using magnetic resonance spectroscopy to detect a biomarker for proliferating progenitor cells that give (...) rise to new neurons.1 This makes it possible to study the role of neural progenitor cells in a wide variety of human brain disorders. BioEssays 30:806–810, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Notre interrogation porte sur la visibilité de la psychologie sociale à travers les forums de discussion Usenet. Ces espaces thématiques communautaires qui permettent d'échanger de très nombreuses informations sous forme de discussions en temps différé, ont servi de support pour interroger la diffusion de la psychologie sociale auprès du grand public. Les archives des forums Usenet ont été interrogées à l'aide des clefs psychosociologie, sociopsychologie et psychologie sociale. Outre les messages liés aux réseaux d'entre-aide et de recherche d'emploi, deux grandes (...) thématiques émergent de l'analyse des messages recueillis: l'utilisation de la psychologie sociale comme caution scientifique pour appuyer le discours émis et une psychologie sociale comme discipline essentiellement manipulatrice. Dans le corpus étudié, celle-ci semble privilégier la manipulation comme objet d'étude - ou en tout cas les individus ne retiendraient que cet objet - et, qui plus est, «manipule» en retour pour obtenir ses résultats.Our study is concerned with the visibility of social psychology through Usenet forums. These virtual communities, which enable the exchange of a multitude of information in discussion forums in non-real time, were the object of our study which explored the popularization of social psychology with the general public. Archives from Usenet were searched using the following keywords: psychosociology, sociopsychology and social psychology. Besides messages linked to help and job-search networks, two main themes emerged from the analysis of messages namely that social psychology is used as a source of scientific evidence to back up the opinions expressed and that socialpsychology is essentially a manipulating discipline. In the studied corpus, socialpsychology seems to privilege manipulation as an object of study - or at least that the individuals involved only remember that aspect – and that it moreover "manipulates" to obtain its results. (shrink)

Six years ago, the Singer lab published a landmark paper which described how individual mRNA particles cross the nuclear pore complex in mammalian tissue culture cells. This involved the simultaneous imaging of mRNAs, each labeled by a large number of tethered fluorescent proteins and fluorescently tagged nuclear pore components. Now two groups have applied this technique to the budding yeast Saccharomyces cerevisiae. Their results indicate that in the course of nuclear export, mRNAs likely engage complexes that are present on (...) either side of the pore and that these interactions are modulated by proteins present in the messenger ribonucleoprotein (mRNP) complex. These findings lend support to the notion that just before and/or after the completion of nuclear export, mRNPs undergo one or more maturation steps that prepare the packaged mRNAs for translation. These results represent new and exciting insights into the mechanism of mRNA nuclear export. (shrink)

Ces dernières années ont été le théâtre d'une étonnante résurgence de la question anthropologique. Parmi les propositions les plus débattues, il y a eu celle qui consisterait à penser l'homme non pas comme un animal doué de langage, mais avant tout comme un homo pictor ou encore comme un homo spectator, capable de produire et de reconnaître ses propres images. Si entre-temps, cette idée d'une anthropologie par l'image a permis d'inaugurer des nouveaux domaines de recherche, comme l'anthropologie visuelle, celle-ci relève (...) cependant d'une histoire déjà plus ancienne dont cet ouvrage livre quelques clés. Entre ceux qui considèrent que les images sont le reflet exact de l'homme et ceux qui, au contraire, sont d'avis que les artefacts visuels mènent une vie dont les raisons échappent à la logique anthropocentrique, se dessinent aujourd'hui les lignes de front de ce qui s'apparente à une nouvelle querelle de l'image. (shrink)

Metaphors allow us to come to terms with abstract and complex information, by comparing it to something which is structured, familiar and concrete. Although modern science is “iconoclastic”, as Gaston Bachelard phrases it, scientists are at the same time prolific producers of metaphoric images themselves. Synthetic biology is an outstanding example of a technoscientific discourse replete with metaphors, including textual metaphors such as the “Morse code” of life, the “barcode” of life and the “book” of life. This paper focuses on (...) a different type of metaphor, however, namely on the archetypal metaphor of the mandala as a symbol of restored unity and wholeness. Notably, mandala images emerge in textual materials related to one of the new “frontiers” of contemporary technoscience, namely the building of a synthetic cell: a laboratory artefact that functions like a cell and is even able to replicate itself. The mandala symbol suggests that, after living systems have been successfully reduced to the elementary building blocks and barcodes of life, the time has now come to put these fragments together again. We can only claim to understand life, synthetic cell experts argue, if we are able to technically reproduce a fully functioning cell. This holistic turn towards the cell as a meaningful whole also requires convergence at the “subject pole”: the building of a synthetic cell as a practice of the self, representing a turn towards integration, of multiple perspectives and various forms of expertise. (shrink)

The complete sequencing of the genome of the fruit fly Drosophila melanogaster offers the prospect of detailed functional analysis of the extensive gene families in this genetic model organism. Comprehensive functional analysis of family members is facilitated by access to a robust, stable and inducible expression system in a fly cell line. Here we show how the Schneider S2 cell line, derived from the Drosophila embryo, provides such an expression system, with the bonus that radioligand binding studies, second (...) messenger assays, ion imaging, patch‐clamp electrophysiology and gene silencing can readily be applied. Drosophila is also ideal for the study of new control strategies for insect pests since the receptors and ion channels that many new animal health drugs and crop protection chemicals target can be expressed in this cell line. In addition, many useful orthologues of human disease genes are emerging from the Drosophila genome and the study of their functions and interactions is another area for postgenome applications of S2 cell lines. BioEssays 24:1066–1073, 2002. © 2002 Wiley‐Periodicals, Inc. (shrink)

Comment une phénoménologie de la vie est-elle possible? Telle est la question que Michel Henry pose à l’égard de sa propre démarche, au moment où celle-ci rencontre l’aporie qu’elle avait elle-même suscitée à travers sa critique de la pensée, c’est-à-dire, aussi et surtout, à travers sa critique du voir de l’intentionnalité. En effet, si la vie est par essence invisible, elle doit se dérober à toute vue et, ainsi, à tout discours qui prétendrait la saisir. Or, c’est là justement ce (...) que prétend faire une phénoménologie de la vie en tant qu’elle est philosophie et “qu’un ouvrage de philosophie n’est autre qu’une série d’intuitions ou d’évidences se voulant liées selon des enchaînements nécessaires et formulées dans des propositions dont la donation – la lecture ou l’écriture – demande elle-même au voir, au Logos grec, sa possibilité.” Il s’agit évidemment d’un problème essentiel, puisque c’est par la réponse qui lui sera donnée que seront décidés, du même coup, la légitimité et la possibilité de la phénoménologie de la vie elle-même. (shrink)

À propos du livre récent de Marlène Albert Llorca, Les Vierges miraculeuses, l’auteur survole rapidement les conclusions de recherches récentes sur l’image religieuse dans l’Europe traditionnelle. Il examine les manières dont les dévots convertissent des images en objets cultuels en les associant à des laïcs importants et aux sanctuaires qui les accueillent. Il commente les conclusions d’Albert Llorca selon lesquelles ces images, vêtues pour la circonstance, peuvent servir à répliquer le “miracle” originel pour les dévots qui manipulent ces vêtements ; (...) ainsi se rejouent les événements miraculeux censés être à l’origine du charisme de l’image. C’est donc l’imaginaire de la communauté, incarné dans les “cameraras” qui habillent l’image, qui dote celle-ci de pouvoirs miraculeux. (shrink)