74,502 research outputs found

    Dual physiological rate measurement instrument

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    The object of the invention is to provide an instrument for converting a physiological pulse rate into a corresponding linear output voltage. The instrument which accurately measures the rate of an unknown rectangular pulse wave over an extended range of values comprises a phase-locked loop including a phase comparator, a filtering network, and a voltage-controlled oscillator, arranged in cascade. The phase comparator has a first input responsive to the pulse wave and a second input responsive to the output signal of the voltage-controlled oscillator. The comparator provides a signal dependent on the difference in phase and frequency between the signals appearing on the first and second inputs. A high-input impedance amplifier accepts an output from the filtering network and provides an amplified output DC signal to a utilization device for providing a measurement of the rate of the pulse wave

    Spin 1 inversion: a Majorana tensor force for deuteron alpha scattering

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    We demonstrate, for the first time, successful S-matrix to potential inversion for spin one projectiles with non-diagonal Sll′jS^j_{ll'} yielding a TRT_{\rm R} interaction. The method is a generalization of the iterative-perturbative, IP, method. We present a test case indicating the degree of uniqueness of the potential. The method is adapted, using established procedures, into direct observable to potential inversion, fitting σ\sigma, iT11{\rm i}T_{11}, T20T_{20}, T21T_{21} and T22T_{22} for d + alpha scattering over a range of energies near 10 MeV. The TRT_{\rm R} interaction which we find is very different from that proposed elsewhere, both real and imaginary parts being very different for odd and even parity channels.Comment: 7 pages Revtex, 4 ps figure

    SIRU Development. Volume 4: Accelerometer Module

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    Estimating components of ICT expenditure: a model-based approach with applicability to short time-series

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    This paper develops a microeconomic model-based approach to forecast national information and communications technology expenditure that is helpful when only very short time-series are available. The model specification incorporates parameters for network effects and national e-readiness. Finally, the model allows for observed non-homotheticity and ‘noise’ found in sample data, with the latter attributed to country-specific influences.ICT forecasts; short time-series; microeconomic modeling

    Internet network externalities

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    Abstract: A driving force behind the emergence of the ‘new’ or information economy is the growth of the internet network capacity. A fundamental problem in mapping this dynamic is the lack of an acceptable theoretical framework through which to direct empirical investigations. Most of the models in the literature on network externalities have been developed in a static framework, with the externalities viewed as instantaneous or self-fulfilling. The model specified here builds on the received theory from several sources to extend these features and develops a dynamic model that is both capable of econometric estimation and which provides as an output a direct measure of the network effect. Accordingly, the main goal of this paper is to find the magnitude of the external effect on internet network growth. In addition, this paper illustrates the ability of the panel data to generate estimates of structural parameters capable of explaining internet host growth.Information; network externalities; internet; growth

    Photoabsorption spectra in the continuum of molecules and atomic clusters

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    We present linear response theories in the continuum capable of describing photoionization spectra and dynamic polarizabilities of finite systems with no spatial symmetry. Our formulations are based on the time-dependent local density approximation with uniform grid representation in the three-dimensional Cartesian coordinate. Effects of the continuum are taken into account either with a Green's function method or with a complex absorbing potential in a real-time method. The two methods are applied to a negatively charged cluster in the spherical jellium model and to some small molecules (silane, acetylene and ethylene).Comment: 13 pages, 9 figure

    Invisibility in non-Hermitian tight-binding lattices

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    Reflectionless defects in Hermitian tight-binding lattices, synthesized by the intertwining operator technique of supersymmetric quantum mechanics, are generally not invisible and time-of-flight measurements could reveal the existence of the defects. Here it is shown that, in a certain class of non-Hermitian tight-binding lattices with complex hopping amplitudes, defects in the lattice can appear fully invisible to an outside observer. The synthesized non-Hermitian lattices with invisible defects possess a real-valued energy spectrum, however they lack of parity-time (PT) symmetry, which does not play any role in the present work.Comment: to appear in Phys. Rev.
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