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  • American Institute of Physics (AIP)  (3)
  • Nature Publishing Group (NPG)  (3)
  • Nature Publishing Group  (1)
  • 2015-2019  (3)
  • 2000-2004  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2129-2131 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The application of high intensity laser-produced gamma rays is discussed with regard to picosecond resolution deep-penetration radiography. The spectrum and angular distribution of these gamma rays is measured using an array of thermoluminescent detectors for both an underdense (gas) target and an overdense (solid) target. It is found that the use of an underdense target in a laser plasma accelerator configuration produces a much more intense and directional source. The peak dose is also increased significantly. Radiography is demonstrated in these experiments and the source size is also estimated. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 413 (2001), S. 349-351 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] On the verge of clinical application, stem cells offer a startlingly fundamental approach to alleviating severe incurable human maladies. Fondly believed to be a recent development, they have in fact been part and parcel of human in-vitro fertilization (IVF) from as long ago as 1962. Stem cells ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 11 (2001), S. 160-169 
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We analyze a class of ordinary differential equations representing a simplified model of a genetic network. In this network, the model genes control the production rates of other genes by a logical function. The dynamics in these equations are represented by a directed graph on an n-dimensional hypercube (n-cube) in which each edge is directed in a unique orientation. The vertices of the n-cube correspond to orthants of state space, and the edges correspond to boundaries between adjacent orthants. The dynamics in these equations can be represented symbolically. Starting from a point on the boundary between neighboring orthants, the equation is integrated until the boundary is crossed for a second time. Each different cycle, corresponding to a different sequence of orthants that are traversed during the integration of the equation always starting on a boundary and ending the first time that same boundary is reached, generates a different letter of the alphabet. A word consists of a sequence of letters corresponding to a possible sequence of orthants that arise from integration of the equation starting and ending on the same boundary. The union of the words defines the language. Letters and words correspond to analytically computable Poincaré maps of the equation. This formalism allows us to define bifurcations of chaotic dynamics of the differential equation that correspond to changes in the associated language. Qualitative knowledge about the dynamics found by integrating the equation can be used to help solve the inverse problem of determining the underlying network generating the dynamics. This work places the study of dynamics in genetic networks in a context comprising both nonlinear dynamics and the theory of computation. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 10 (2000), S. 691-704 
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The explosive growth in knowledge of the genome of humans and other organisms leaves open the question of how the functioning of genes in interacting networks is coordinated for orderly activity. One approach to this problem is to study mathematical properties of abstract network models that capture the logical structures of gene networks. The principal issue is to understand how particular patterns of activity can result from particular network structures, and what types of behavior are possible. We study idealized models in which the logical structure of the network is explicitly represented by Boolean functions that can be represented by directed graphs on n-cubes, but which are continuous in time and described by differential equations, rather than being updated synchronously via a discrete clock. The equations are piecewise linear, which allows significant analysis and facilitates rapid integration along trajectories. We first give a combinatorial solution to the question of how many distinct logical structures exist for n-dimensional networks, showing that the number increases very rapidly with n. We then outline analytic methods that can be used to establish the existence, stability and periods of periodic orbits corresponding to particular cycles on the n-cube. We use these methods to confirm the existence of limit cycles discovered in a sample of a million randomly generated structures of networks of 4 genes. Even with only 4 genes, at least several hundred different patterns of stable periodic behavior are possible, many of them surprisingly complex. We discuss ways of further classifying these periodic behaviors, showing that small mutations (reversal of one or a few edges on the n-cube) need not destroy the stability of a limit cycle. Although these networks are very simple as models of gene networks, their mathematical transparency reveals relationships between structure and behavior, they suggest that the possibilities for orderly dynamics in such networks are extremely rich and they offer novel ways to think about how mutations can alter dynamics. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Publication Date: 2018-05-16
    Description: Transition to chronic pain: opportunities for novel therapeutics Transition to chronic pain: opportunities for novel therapeutics, Published online: 15 May 2018; doi:10.1038/s41583-018-0012-5 Although chronic pain is one of the most important medical problems facing society, there has been very limited progress in the development of novel therapies for this condition. Here, we discuss high-impact research priorities to reduce the number of people transitioning from acute to chronic intractable pain.
    Print ISSN: 1471-003X
    Electronic ISSN: 1471-0048
    Topics: Biology , Medicine
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  • 6
    Publication Date: 2018-09-13
    Description: Structural basis for importin alpha 3 specificity of W proteins in Hendra and Nipah viruses Structural basis for importin alpha 3 specificity of W proteins in Hendra and Nipah viruses, Published online: 12 September 2018; doi:10.1038/s41467-018-05928-5 Importin α isoforms regulate the nuclear import of different cargo proteins but the mechanisms conferring isoform specificity are not fully understood. Here, the authors study the interactions of importin α1 and α3 with two viral cargos, elucidating the structural basis for isoform-specific cargo recognition.
    Electronic ISSN: 2041-1723
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2018-02-28
    Description: HIF1α drives chemokine factor pro-tumoral signaling pathways in acute myeloid leukemia HIF1α drives chemokine factor pro-tumoral signaling pathways in acute myeloid leukemia, Published online: 28 February 2018; doi:10.1038/s41388-018-0151-1 HIF1α drives chemokine factor pro-tumoral signaling pathways in acute myeloid leukemia
    Print ISSN: 0950-9232
    Topics: Medicine
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