398 research outputs found

    Czas wykraczania poza gen

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    Coraz częściej celem badań w laboratoriach biologicznych nie jest już gromadzenie danych, ale zrozumienie ich funkcji. Nie zadowalamy się już strukturalnym odwzorowaniem, ponownie interesuje nas to, co Amerykański Departament Energii (United States Department of Energy, dalej DOE) nazywa „Przywracaniem Genomów Życiu” (Bringing Genomes to Life). Dla wielu osób oznacza to wyjście poza „redukcjonizm” w stronę „biologii systemowej”. Pytanie tylko, co to oznacza

    Organisms, Machines, and Thunderstorms: A History of Self-Organization, Part Two. Complexity, Emergence, and Stable Attractors

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    Part Two of this essay focuses on what might be called the third and most recent chapter in the history of self-organization, in which the term has been claimed to denote a paradigm shift or revolution in scientific thinking about complex systems. The developments responsible for this claim began in the late 1960s and came directly out of the physical sciences. They rapidly attracted wide interest and led to yet another redrawing of the boundaries between organisms, machines, and naturally occurring physical systems (such as thunderstorms). In this version of self-organization, organisms are once again set apart from machines precisely because the latter depend on an outside designer, but—in contrast to Kant's ontology—they are now assimilated to patterns in the inorganic world on the grounds that they, too, like many biological phenomena, arise spontaneously

    Genes, genomes, and codes : revisiting some key terms with multiple meanings

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    Is a genome the full complement of an organism?s genes or of its DNA? Is genetics the study of genes or of heredity? Is the genetic code the mechanism for translating nucleotide sequence to amino acid sequence or to phenotype? Does «genetic information» refer to the sequences coding for proteins or to all DNA sequences? Each of these questions stems from an elision between one, concrete, meaning, and another, open-ended and ambiguous. Such elision invites the illusion that the ambiguity of the open-ended term has been resolved, and by implication, that the gap between actual achievement and promise has been closed. Yet, despite the phenomenal progress molecular biology has made, we remain without an adequate account of the organization of proteins into an organism

    Historical and Philosophical Perspectives on Contemporary Biology

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    Evelyn Fox Keller introduces a new series that aims to promote productive dialogue between laboratory researchers and historians and philosophers of science to address the challenges arising from the rapid pace of biological discovery

    Evidence for Coexistence of Bulk Superconductivity and Itinerant Antiferromagnetism in the Heavy Fermion System CeCo(In1x_{1-x}Cdx_x)5_5

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    In the generic phase diagram of heavy fermion systems, tuning an external parameter such as hydrostatic or chemical pressure modifies the superconducting transition temperature. The superconducting phase forms a dome in the temperature-tuning parameter phase diagram, which is associated with a maximum of the superconducting pairing interaction. Proximity to antiferromagnetism suggests a relation between the disappearance of antiferromagnetic order and superconductivity. We combine muon spin rotation, neutron scattering, and x-ray absorption spectroscopy techniques to gain access to the magnetic and electronic structure of CeCo(In1x_{1-x}Cdx_x)5_5 at different time scales. Different magnetic structures are obtained that indicate a magnetic order of itinerant character, coexisting with bulk superconductivity. The suppression of the antiferromagnetic order appears to be driven by a modification of the bandwidth/carrier concentration, implying that the electronic structure and consequently the interplay of superconductivity and magnetism is strongly affected by hydrostatic and chemical pressure.Comment: Article + Supplementary information 33 pages, 13 figure

    L’anomalia d’una dona en la física

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    Traducció a cura de Sònia Estradé de l'article d'Evelyn Fox Keller de 197

    The future of human nature: a symposium on the promises and challenges of the revolutions in genomics and computer science, April 10, 11, and 12, 2003

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    This repository item contains a single issue of the Pardee Conference Series, a publication series that began publishing in 2006 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future. This was the Center's Symposium on the Promises and Challenges of the Revolutions in Genomics and Computer Science took place during April 10, 11, and 12, 2003. Co-organized by Charles DeLisi and Kenneth Lewes; sponsored by Boston University, the Frederick S. Pardee Center for the Study of the Longer-Range Future.This conference focused on scientific and technological advances in genetics, computer science, and their convergence during the next 35 to 250 years. In particular, it focused on directed evolution, the futures it allows, the shape of society in those futures, and the robustness of human nature against technological change at the level of individuals, groups, and societies. It is taken as a premise that biotechnology and computer science will mature and will reinforce one another. During the period of interest, human cloning, germ-line genetic engineering, and an array of reproductive technologies will become feasible and safe. Early in this period, we can reasonably expect the processing power of a laptop computer to exceed the collective processing power of every human brain on the planet; later in the period human/machine interfaces will begin to emerge. Whether such technologies will take hold is not known. But if they do, human evolution is likely to proceed at a greatly accelerated rate; human nature as we know it may change markedly, if it does not disappear altogether, and new intelligent species may well be created

    A supervised clustering approach for fMRI-based inference of brain states

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    We propose a method that combines signals from many brain regions observed in functional Magnetic Resonance Imaging (fMRI) to predict the subject's behavior during a scanning session. Such predictions suffer from the huge number of brain regions sampled on the voxel grid of standard fMRI data sets: the curse of dimensionality. Dimensionality reduction is thus needed, but it is often performed using a univariate feature selection procedure, that handles neither the spatial structure of the images, nor the multivariate nature of the signal. By introducing a hierarchical clustering of the brain volume that incorporates connectivity constraints, we reduce the span of the possible spatial configurations to a single tree of nested regions tailored to the signal. We then prune the tree in a supervised setting, hence the name supervised clustering, in order to extract a parcellation (division of the volume) such that parcel-based signal averages best predict the target information. Dimensionality reduction is thus achieved by feature agglomeration, and the constructed features now provide a multi-scale representation of the signal. Comparisons with reference methods on both simulated and real data show that our approach yields higher prediction accuracy than standard voxel-based approaches. Moreover, the method infers an explicit weighting of the regions involved in the regression or classification task
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