308 research outputs found

    Toxicity of perfluorinated carboxylic acids for aquatic organisms

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    Toxicity of perfluorinated carboxylic acids with carbon chain C8 to C12 were tested with oligochaeta Tubifex tubifex. Toxicity was evaluated as the exposure time ET50 from onset of damage of the oligochaeta in saturated aqueous solutions. The ET50 fluctuated between 25 and 257 minutes. No statistically significant difference was found among the C8, C9 and C12 acids (ET50 between 143 and 257 minutes with large standard deviation). The acids with carbon chain C10 and C11 induced the effect significantly quicker (25 to 47 minutes). No acute toxicity measured in the three-minute test was observed in any case

    Human urine certified reference material CZ 6010: creatinine and toluene metabolites (hippuric acid and o-cresol) and a benzene metabolite (phenol)

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    A reference material for the biological monitoring of occupational exposure to toluene, benzene and phenol was prepared. O-cresol and hippuric acid (metabolites of toluene) are used for the biological monitoring of occupational exposure to toluene. Phenol, a metabolite of benzene, is used for the biological monitoring of exposure to benzene, but phenol can of course also be used as an indicator of exposure to phenol as well. The reference material (RM) used for the determination of these metabolites was prepared by freeze-drying pooled urine samples obtained from healthy persons occupationally exposed to toluene and those taking part in an inhalation experiment. Tests for homogeneity and stability were performed by determining urine concentrations of o-cresol, hippuric acid, creatinine and phenol. To investigate the stability of the RM, the urinary concentrations of o-cresol and phenol were monitored for eighteen months using GC and HPLC, while those of hippuric acid and creatinine were followed for five and six years, respectively, using HPLC. Analysis of variance showed that the concentrations did not change. The certified concentration values (and their uncertainties) of the substances in this reference material (phenol concentration c=6.46+/-0.58 mg l(-1); o-cresol concentration c=1.17+/-0.15 mg l(-1); hippuric acid concentration c=1328+/-30 mg l(-1); creatinine concentration c=0.82+/-0.10 g l(-1)) were evaluated via the interactive statistical programme IPECA

    PREDICATION AND EXTENSIONALIZATION

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    In his 2000 book Logical Properties Colin McGinn argues that predicates denote properties rather than sets or individuals. I support the thesis, but show that it is vulnerable to a type-incongruity objection, if properties are (modelled as) functions, unless a device for extensionalizing properties is added. Alternatively, properties may be construed as primitive intensional entities, as in George Bealer. However, I object to Bealer’s construal of predication as a primitive operation inputting two primitive entities and outputting a third primitive entity. Instead I recommend we follow Pavel Tichý in construing both predication and extensionalization as instances of the primitive operation of functional application.PhilosophyTechnology, Policy and Managemen

    Reliability of Human Subject - Artificial System Interactions

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    Main problems related to reliability of interaction between human subject and artificial system (namely of the transportation character) are discussed. The paper consists of three mayor parts:The first one is devoted to the theoretical backgrounds of the problem from the both theory of system reliability and neurology/psychology views.Second part presents the discussion of relevant methodologies of the classification and prediction of the reliability decline. The methodology based on EEG pattern analysis is chosen as the appropriate one for the presented task. The key phenomenon of "micro-sleep" is discussed in detail.The last part presents some latest experimental results in context of presented knowledge. Proposals for the future studies are presented at the end of the presented article. The special interest should be devoted to the analysis and in-time prediction of fatal attention decreases and to the design and construction of the respective on-board applicable warning system

    Preliminary measurements of lumbar spine kinematics and stiffness

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    The purpose of the presented study was the experimental measurement of lumbar spine stiffness and its range of motion. The dependence of torsion moment of lumbar spine segment on deflection of flexion, extension and torsion was observed during experiments. Stiffness of spine segment was determined from measured data. Human lumbar spine was used for verification of the experimental technique. The sample consisted of one lumbar vertebrae composed by five vertebral bodies and four intervertebral discs. All muscles were removed, however all ligaments were preserved. Experiments were ca rried out on the test system MTS 858.2 MiniBionix, where loading by axial force and torsion moment is possible at the same time. Special Modular Bionix Spine Test Fixator, attached to the test system was used for the measurements. Loading was controlled kinematically (gradual turning) by keeping the axial force equal zero. Measurement was timedependent. The results of these experiments are going to be used as input data for creating a model of artificial lumbar spine and new type of artificial disc replacement

    Lobster eye optics for nano-satellite x-ray monitor

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    The Lobster eye design for a grazing incidence X-ray optics provides wide field of view of the order of many degrees, for this reason it would be a convenient approach for the construction of space X-ray monitors. In this paper, we compare previously reported measurements of prototype lobster eye X-ray optics called P-25 with computer simulations and discuss differences between the theoretical end experimentally obtained results. Usability of this prototype lobster eye and manufacturing technology for the nano-satellite mission is assessed. The specific scientific goals are proposed

    On Chebyshev Polynomials of Matrices

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    Monitoring mixed neutron-proton field near the primary proton and deuteron beams in spallation targets

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    282-293At the Joint Institute for Nuclear Research (JINR) we are involved in the Accelerator-Driven-System (ADS) research. We perform experiments with assemblies composed of a spallation target and a subcritical blanket irradiated with high-energy proton or deuteron beams that generate high-energy neutron fields by spallation and fission reactions. In this paper, three uranium assemblies are presented: Energy plus Transmutation (E+T), QUINTA and BURAN. We discuss the results of the E+T and QUINTA irradiations by 1.6 GeV deuterons and 660 MeV protons, respectively. We have focused on the regions close to the primary beam passage through the targets. The field has been measured using activation detectors of 209Bi, 59Co, and natPb. Monte Carlo simulations using MCNPX 2.7.0 have been performed and compared to the experimental results. We discovered that the field intensity near the primary beam is very dependent on the precision of the accelerator beam settings. Therefore, a Monte Carlo-based study of the influence of the uncertainty of primary proton beam parameters on experimental result accuracy of the QUINTA assembly has been carried out. The usage of MCNPX 2.7.0 in the future BURAN irradiations has been assessed.</span
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