16,070 research outputs found

    The accumulation of the cyanobacterial toxin, microcystin, in cherry tomato (Solanum lycopersicum) and bush bean (Phaseolus vulgaris) plants

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    We aimed to develop a high-sensitivity method to detect microcystin toxins in fruit tissue and to determine if irrigation with water containing toxic cyanobacteria may result in accumulation of microcystin toxins in fruit tissue and affect fruit development. In a greenhouse experiment bush beans (Phaseolus vulgaris) and tomato plants (Solanum lycopersicum) were grown in the summer under natural light and temperature between the months of September and August. Mature plants received treatments of toxic, Microcystis aeruginosa, applied twice weekly to the soil. To simulate naturally contaminated irrigation water, the M. aeruginosa were applied to plants as a suspension of intact cells. After harvesting, fruiting bodies (beans and tomatoes) were homogenized and extracted with 80% methanol (MeOH) and analyzed by ELISA for microcystins. The first extraction method tested the extraction of 0.45 g fruit tissue in 1.5 mL MeOH, buffered with PBS after 24 hr and yielded MC concentrations just above detectable limits of the ELISA. The second extraction method concentrated samples using a SpeedVac and yielded MC concentrations in range of the ELISA. The third method filtered samples from Method 2 as a preliminary investigation into matrix effects and reduced MC concentration on an average of 84%. To determine if Microcystis affected the growth of the plant’s fruit, all harvested beans and tomatoes were individually measured, weighed and photographed before processing their tissue for ELISA. The presence of cyanobacteria stimulated bean growth (t-Test P\u3c0.05), although there was no effect on the size or growth of tomatoes. Treated plants produced more fruit than the controls, although the difference was not statistically significant. The high - sensitivity method of MC extraction allows for detection of the cyanotoxins and microcystins, in the fruiting bodies of plants and an assessment of the health risk to humans and livestock

    A computer architecture for intelligent machines

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    The Theory of Intelligent Machines proposes a hierarchical organization for the functions of an autonomous robot based on the Principle of Increasing Precision With Decreasing Intelligence. An analytic formulation of this theory using information-theoretic measures of uncertainty for each level of the intelligent machine has been developed in recent years. A computer architecture that implements the lower two levels of the intelligent machine is presented. The architecture supports an event-driven programming paradigm that is independent of the underlying computer architecture and operating system. Details of Execution Level controllers for motion and vision systems are addressed, as well as the Petri net transducer software used to implement Coordination Level functions. Extensions to UNIX and VxWorks operating systems which enable the development of a heterogeneous, distributed application are described. A case study illustrates how this computer architecture integrates real-time and higher-level control of manipulator and vision systems

    Science opportunities from the Topex/Poseidon mission

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    The U.S. National Aeronautics and Space Administration (NASA) and the French Centre National d'Etudes Spatiales (CNES) propose to conduct a Topex/Poseidon Mission for studying the global ocean circulation from space. The mission will use the techniques of satellite altimetry to make precise and accurate measurements of sea level for several years. The measurements will then be used by Principal Investigators (selected by NASA and CNES) and by the wider oceanographic community working closely with large international programs for observing the Earth, on studies leading to an improved understanding of global ocean dynamics and the interaction of the ocean with other processes influencing life on Earth. The major elements of the mission include a satellite carrrying an altimetric system for measuring the height of the satellite above the sea surface; a precision orbit determination system for referring the altimetric measurements to geodetic coordinates; a data analysis and distribution system for processing the satellite data, verifying their accuracy, and making them available to the scientific community; and a principal investigator program for scientific studies based on the satellite observations. This document describes the satellite, its sensors, its orbit, the data analysis system, and plans for verifying and distributing the data. It then discusses the expected accuracy of the satellite's measurements and their usefulness to oceanographic, geophysical, and other scientific studies. Finally, it outlines the relationship of the Topex/Poseidon mission to other large programs, including the World Climate Research Program, the U.S. Navy's Remote Ocean Sensing System satellite program and the European Space Agency's ERS-1 satellite program

    The influence of turbulence on the structure and propagation of enclosed flames

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    Although it has long been established that burning rates can be appreciably increased by turbulence, the actual extent of this increase and the precise mechanism involved are still far from clear. The object of the present research was to examine the effects of turbulence on burning velocity and on the physical structure of the flame surface under flow conditions similar to those experienced in turbojet afterburner systems

    Propagation of Errors for Matrix Inversion

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    A formula is given for the propagation of errors during matrix inversion. An explicit calculation for a 2 by 2 matrix using both the formula and a Monte Carlo calculation are compared. A prescription is given to determine when a matrix with uncertain elements is sufficiently nonsingular for the calculation of the covariances of the inverted matrix elements to be reliable.Comment: 18 pages, 4 figures, figure 4 contains two eps file

    Repetition and difference: Lefebvre, Le Corbusier and modernity's (im)moral landscape: a commentary

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    This article engages with the relationship between social theory, architectural theory and material culture. The article is a reply to an article in a previous volume of the journal in question (Smith, M. (2001) ‘Repetition and difference: Lefebvre, Le Corbusier and modernity’s (im)moral landscape’, Ethics, Place and Environment, 4(1), 31-34) and, consequently, is also a direct engagement with another academic's scholarship. It represents a critique of their work as well as a recasting of their ideas, arguing that the matter in question went beyond interpretative issues to a direct critique of another author's scholarship on both Le Corbusier and Lefebvre. A reply to my article from the author of the original article was carried in a later issue of the journal (Smith, M. (2002) ‘Ethical Difference(s): a Response to Maycroft on Le Corbusier and Lefebvre’, Ethics, Place and Environment, 5(3), 260-269)

    Superconductivity and short range order in metallic glasses Fex_{x}Ni1x_{1-x}Zr2_{2}

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    In amorphous superconductors, superconducting and vortex pinning properties are strongly linked to the absence of long range order. Consequently, superconductivity and vortex phases can be studied to probe the underlying microstructure and order of the material. This is done here from resistance and local magnetization measurements in the superconducting state of Fex_{x}Ni1x_{1-x}Zr2_{2} metallic glasses with 0x0.60\leq x \leq 0.6. Firstly, we present typical superconducting properties such as the critical temperature and fields and their dependence on Fe content in these alloys. Then, the observations of peculiar clockwise hysteresis loops, wide double-step transitions and large magnetization fluctuations in glasses containing a large amount of Fe are analyzed to reveal a change in short range order with Fe content.Comment: 8 pages, 7 figure

    Induction chemotherapy in locally advanced squamous cell carcinoma of the head and neck: role, controversy, and future directions.

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    BackgroundThe value of induction chemotherapy (ICT) remains under investigation despite decades of research. New advancements in the field, specifically regarding the induction regimen of choice, have reignited interest in this approach for patients with locally advanced squamous cell carcinoma of the head and neck (LA SCCHN). Sufficient evidence has accumulated regarding the benefits and superiority of TPF (docetaxel, cisplatin, and fluorouracil) over the chemotherapy doublet cisplatin and fluorouracil. We therefore sought to collate and interpret the available data and further discuss the considerations for delivering ICT safely and optimally selecting suitable post-ICT regimens.DesignWe nonsystematically reviewed published phase III clinical trials on TPF ICT in a variety of LA SCCHN patient populations conducted between 1990 and 2017.ResultsTPF may confer survival and organ preservation benefits in a subgroup of patients with functionally inoperable or poor-prognosis LA SCCHN. Additionally, patients with operable disease or good prognosis (who are not candidates for organ preservation) may benefit from TPF induction in terms of reducing local and distant failure rates and facilitating treatment deintensification in selected populations. The safe administration of TPF requires treatment by a multidisciplinary team at an experienced institution. The management of adverse events associated with TPF and post-ICT radiotherapy-based treatment is crucial. Finally, post-ICT chemotherapy alternatives to cisplatin concurrent with radiotherapy (i.e. cetuximab or carboplatin plus radiotherapy) appear promising and must be investigated further.ConclusionsTPF is an evidence-based ICT regimen of choice in LA SCCHN and confers benefits in suitable patients when it is administered safely by an experienced multidisciplinary team and paired with the optimal post-ICT regimen, for which, however, no consensus currently exists
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