1,721,103 research outputs found
Establishment of the antiviral state in alpha, beta interferon-resistant Friend cells treated with gamma interferon: induction of 67K protein kinase activity in absence of detectable 2-5A synthetase
No full textTreatment with murine gamma-interferon (IFN) preparations of variant sublines of Friend leukemia cells resistant to the alpha, beta IFN-induced antiviral state (Affabris, E., Jemma, C., and Rossi, G.B. (1982) Virology 120, 441-452; Affabris, E., Romeo, G., Belardelli, F., Jemma, C., Mechti, N., Gresser, I., and Rossi, G. B. (1983) Virology 125, 508-512) results in the establishment of a bona fide antiviral state. In fact, gamma IFN preparations are able to induce a dose-dependent reduction of endogenous virus release and of vesicular stomatitis or encephalomyocarditis viruses yields (up to 1.5 log). Under these experimental conditions, no inducible 2-5A synthetase activity is detectable in cell extracts. The 67-kDa protein kinase, uninducible by treatment with alpha, beta IFN (up to 13,000 units/ml), is instead induced upon treatment with gamma IFN at a similar rate of activity as in wild-type Friend leukemia cells, both when assayed in solution and after immobilization on poly(rI) X poly(rC)-agarose
Beyond the opposition between the Bayesian and the frequentistic views in measurement
No full textThe probabilistic modelling of measurement systems is discussed, showing how it provides a practical and effective way for addressing uncertainty evaluation, that does not require any commitment to specific philosophical schools, such as the frequentistic and the Bayesian ones. Firstly, different ways of modelling the same measuring device are compared and discussed, considering both the designer's and the user's standpoints. Then philosophical issues concerning both the nature of probability and the probabilistic inferences related to the measurement process are considered, in the perspective of this model-based approach. Applications to education and to the revision of international guides for measurement are finally addressed
Probabilistic measurement modelling may overcome the opposition between the Bayesian and the frequentistic views
No full textToward a unified framework for static and dynamic measurements
No full textA general probabilistic model of the measurement process is discussed, showing how it can address both static and dynamic measurements. Emphasis is placed on the latter and two main kinds of dynamic measurements are considered: direct, where the goal is to monitor a phenomenon over time, and indirect, where an alternative representation is sought, such as, typically, the spectrum. It is shown that both cases can be treated in the same framework, through a proper interpretation of the variables involved. Guidelines for the application of this approach are also provided
Power measurement in maximum height jump
No full textAthletes performance can be evaluated through different tests generally specifically designed to consider a specific quality. When dealing with explosive power, maximum height jump is widely used. Athlete's performance may be evaluated through different parameters such as elevation differential, excursion of the center of mass in vertical direction, or in more detailed way, through a power measurement. A few methods can be considered for this purpose and the aim of this paper is to compare them, providing guidelines for their application and for measurement-uncertainty evaluation, as far as possible for such a gesture, considering the complexity of the measurement
Measurement uncertainty: A probabilistic theory for intensive entities
No full textThe need of technically assessing the properties of an increasing number of objects requires a considerable effort, for issuing the metrological standards, granting theoretical and practical traceability of both the ranking scales and the accuracy figures. The representational theory of measurements is deserving great interest since it provides a simple constructive paradigm for the homogeneous generation of metrological scales and measurements procedures of any kind of attributes (qualities and quantities). This theory, however, still suffers of practical limitations; in particular, the treatment of uncertainty in measurements is not fully formalized. The paper proposes a probabilistic interpretation that coherently models the uncertainty in the measurement of intensive entities. The new theoretical assessments are related to the current standards, and the appropriate propositions are justified with examples. © 1995
Assessing measurement uncertainty in quality engineering
No full textThe automatic restitution of measurement uncertainty with related current results is required for rationalising the specificity and for improving the effectiveness of the industrial instrumentation, used for standard quality engineering tasks. The paper introduces to a general probabilistic frame, based on the propagation of distribution densities, associated to actual experimental data, so that the inclusion of every pertinent information can be done, while transparently acknowledging the influence factors. The approach is explained referring to example case situations
Probabilistic decision making for the implementation of the Measuring Instrument Directive
No full textThe approval of the European Measuring Instrument Directive on April 2004 renews completely the legal metrology sector, proposing a "new approach" aiming to technical normalization and harmonization and toward a "global approach" to evaluation and conformity. According to the principles of the "new approach" regulatory model, the Directive leaves to the manufacturer itself to adopt proper technical solutions, giving only very essential requirements, without going in any detail. Moreover new certification procedures based on Quality Systems are available and there is no indication regarding the procedure to verify product conformity. In the present paper, after a brief discussion regarding the MID philosophy, a probabilistic approach to conformity assessment is presented. The proposed approach covers a set of open issues such as the measurement uncertainty due to the influence of operating conditions, the management of the risk due to conformity decision based upon a set of measurement results, the costs of instrument uncertainty and eventually non conformity for the manufacturer and instrument user. The approach is supported by a set of software codes enabling an easy and user friendly application. All these aspects are presented with reference to the case of water meters, considering both the end of production acceptance tests and the operative situation of the meter
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