84,403 research outputs found

    \u3cem\u3eAnolis\u3c/em\u3e Sex Chromosomes Are Derived from A Single Ancestral Pair

    Get PDF
    To explain the frequency and distribution of heteromorphic sex chromosomes in the lizard genus Anolis, we compared the relative roles of sex chromosome conservation versus turnover of sex‐determining mechanisms. We used model‐based comparative methods to reconstruct karyotype evolution and the presence of heteromorphic sex chromosomes onto a newly generated Anolis phylogeny. We found that heteromorphic sex chromosomes evolved multiple times in the genus. Fluorescent in situ hybridization (FISH) of repetitive DNA showed variable rates of Y chromosome degeneration among Anolis species and identified previously undetected, homomorphic sex chromosomes in two species. We confirmed homology of sex chromosomes in the genus by performing FISH of an X‐linked bacterial artificial chromosome (BAC) and quantitative PCR of X‐linked genes in multiple Anolis species sampled across the phylogeny. Taken together, these results are consistent with long‐term conservation of sex chromosomes in the group. Our results pave the way to address additional questions related to Anolis sex chromosome evolution and describe a conceptual framework that can be used to evaluate the origins and evolution of heteromorphic sex chromosomes in other clades

    Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagetic anomalies prior to the L'Aquila earthquake as pre-seismic ones. Part I

    Get PDF
    Ultra low frequency, kHz and MHz electromagnetic anomalies were recorded prior to the L'Aquila catastrophic earthquake that occurred on April 6, 2009. The main aims of this contribution are: (i) To suggest a procedure for the designation of detected EM anomalies as seismogenic ones. We do not expect to be possible to provide a succinct and solid definition of a pre-seismic EM emission. Instead, we attempt, through a multidisciplinary analysis, to provide elements of a definition. (ii) To link the detected MHz and kHz EM anomalies with equivalent last stages of the L'Aquila earthquake preparation process. (iii) To put forward physically meaningful arguments to support a way of quantifying the time to global failure and the identification of distinguishing features beyond which the evolution towards global failure becomes irreversible. The whole effort is unfolded in two consecutive parts. We clarify we try to specify not only whether or not a single EM anomaly is pre-seismic in itself, but mainly whether a combination of kHz, MHz, and ULF EM anomalies can be characterized as pre-seismic one

    Hybrid dispersion laser scanner.

    Get PDF
    Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points

    Managament in a New and Experimentally Organized Economy

    Get PDF
    The parallel development of management theory and practice over three phases of economic development is surveyed; (1) the pre-oil crisis experience 1969-1975, (2) the post oil crisis sobering up through most of the 1990s and (3) the emergence of new global production organizations , blurring the notion of the firm to be managed. The external market circumstances of each period dictate different structures of business operations ; (a) a steady state and predictable environment, (b) crisis, inflation and disorderly markets and (c) new technology supporting a globally distributed production organization. As a consequence structural learning between the periods has been of limited value and often outright misleading. The influence of management theory on management practice and its origin in the received economic equilibrium model are discussed, and an alternative management theory based on the theory of the Experimentally Organized Economy (EOE) presented. The increased rate of failure among large firms is related to the increasing complexity of business decisions in globally distributed production and the decreased reliability of learning . It is concluded that successful management practice develops through experimentation in markets and that the best management education has been a varied career in many lines of business and in several companies.Competence bloc theory; Experimentally Organized Economy (EOE); Management theory; WAD theory; Firm Dynamics; Learning

    Structural Material Property Tailoring Using Deep Neural Networks

    Full text link
    Advances in robotics, artificial intelligence, and machine learning are ushering in a new age of automation, as machines match or outperform human performance. Machine intelligence can enable businesses to improve performance by reducing errors, improving sensitivity, quality and speed, and in some cases achieving outcomes that go beyond current resource capabilities. Relevant applications include new product architecture design, rapid material characterization, and life-cycle management tied with a digital strategy that will enable efficient development of products from cradle to grave. In addition, there are also challenges to overcome that must be addressed through a major, sustained research effort that is based solidly on both inferential and computational principles applied to design tailoring of functionally optimized structures. Current applications of structural materials in the aerospace industry demand the highest quality control of material microstructure, especially for advanced rotational turbomachinery in aircraft engines in order to have the best tailored material property. In this paper, deep convolutional neural networks were developed to accurately predict processing-structure-property relations from materials microstructures images, surpassing current best practices and modeling efforts. The models automatically learn critical features, without the need for manual specification and/or subjective and expensive image analysis. Further, in combination with generative deep learning models, a framework is proposed to enable rapid material design space exploration and property identification and optimization. The implementation must take account of real-time decision cycles and the trade-offs between speed and accuracy

    Earth observations from space: Outlook for the geological sciences

    Get PDF
    Remote sensing from space platforms is discussed as another tool available to geologists. The results of Nimbus observations, the ERTS program, and Skylab EREP are reviewed, and a multidisciplinary approach is recommended for meeting the challenges of remote sensing
    corecore