6,682 research outputs found

    Medical diagnosis system and method with multispectral imaging

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    A skin diagnosis system includes a scanning and optical arrangement whereby light reflected from each incremental area (pixel) of the skin is directed simultaneously to three separate light filters, e.g., IR, red, and green. As a result, the three devices simultaneously produce three signals which are directly related to the reflectance of light of different wavelengths from the corresponding pixel. These three signals for each pixel after processing are used as inputs to one or more output devices to produce a visual color display and/or a hard copy color print, for one usable as a diagnostic aid by a physician

    Direct measurement of the maximum tunnel rate in a radio frequency single electron transistor operated as a microwave mixer

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    By operating the radio frequency single electron transistor (rf-SET) as a mixer we present measurements in which the RC roll-off of the tunnel junctions is observed at high frequencies. Our technique makes use of the non-linear rf-SET transconductance to mix high frequency gate signals and produce difference-frequency components that fall within the bandwidth of the rf-SET. At gate frequencies >15GHz the induced charge on the rf-SET island is altered on time-scales faster than the inverse tunnel rate, preventing mixer operation. We suggest the possibility of utilizing this technique to sense high frequency signals beyond the usual rf-SET bandwidth.Comment: Submitted to Applied Physics Letters. Comments always very welcome, email:[email protected] (New version contains extra data and new figs

    A Simple and Flexible Dynamic Approach to Foreign Direct Investment Growth: The Canada-United States Relationship in the Context of Free Trade.

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    This paper asks a simple question: Did Wilfred Laurier’s dream of free trade with the United States, when it came to fruition in 1989, also impact on foreign direct investment (FDI) into Canada by US multinationals? This paper argues that the customary static econometric approach found in the FDI literature, along with the assumption that policy changes influence only the intercept term, are inadequate to address the question. Instead we introduce an innovative dynamic framework to support the testing of hypotheses on behavioural changes in the variables using a structural break framework. A key conclusion is that prior to signing the free trade agreement US FDI responded only to current growth in the Canadian economy, in a unitary fashion, and current exchange rate shifts. This can be described as a static relationship. The implementation of the free trade agreements between Canada and the USA increased the responsiveness of US FDI to growth in the Canadian economy by a factor greater than two. Furthermore, dynamics are found in the form of a lagged effect for changes in the growth in the Canadian economy and interest rate differentials. These conclusions challenge the dominant view, including that in official policy circles, that the free trade agreement had no impact on US firms’ FDI decisions in Canada. Note: Previous versions of this paper were entitled: “A Simple and Flexible Dynamic Approach to Foreign Direct Investment Growth: Did Canada Benefit From the Free Trade Agreements with the United States?”Canada-United States, foreign direct investment, empirical relationship

    X-ray absorption study of Ti-activated sodium aluminum hydride

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    Ti K-edge x-ray absorption near edge spectroscopy (XANES) was used to explore the Ti valence and coordination in Ti-activated sodium alanate. An empirical relationship was established between the Ti valence and the Ti K-edge onset based on a set of standards. This relationship was used to estimate oxidation states of the titanium catalyst in 2 mol% and 4 mol% Ti-doped NaAlH4. These results demonstrate that the formal titanium valence is zero in doped sodium alanate and nearly invariant during hydrogen cycling. A qualitative comparison of the edge fine structure suggests that the Ti is present on the surface in the form of amorphous TiAl3.Comment: 3 pages, 4 figures, submitted to Appl. Phys. Let

    Laser induced spark ignition of methane-oxygen mixtures

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    Results from an experimental study of laser induced spark ignition of methane-oxygen mixtures are presented. The experiments were conducted at atmospheric pressure and 296 K under laminar pre-mixed and turbulent-incompletely mixed conditions. A pulsed, frequency doubled Nd:YAG laser was used as the ignition source. Laser sparks with energies of 10 mJ and 40 mJ were used, as well as a conventional electrode spark with an effective energy of 6 mJ. Measurements were made of the flame kernel radius as a function of time using pulsed laser shadowgraphy. The initial size of the spark ignited flame kernel was found to correlate reasonably well with breakdown energy as predicted by the Taylor spherical blast wave model. The subsequent growth rate of the flame kernel was found to increase with time from a value less than to a value greater than the adiabatic, unstretched laminar growth rate. This behavior was attributed to the combined effects of flame stretch and an apparent wrinkling of the flame surface due to the extremely rapid acceleration of the flame. The very large laminar flame speed of methane-oxygen mixtures appears to be the dominant factor affecting the growth rate of spark ignited flame kernels, with the mode of ignition having a small effect. The effect of incomplete fuel-oxidizer mixing was found to have a significant effect on the growth rate, one which was greater than could simply be accounted for by the effect of local variations in the equivalence ratio on the local flame speed

    Global satellite triangulation and trilateration for the National Geodetic Satellite Program (solutions WN 12, 14 and 16)

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    A multi-year study and analysis of data from satellites launched specifically for geodetic purposes and from other satellites useful in geodetic studies was conducted. The program of work included theoretical studies and analysis for the geometric determination of station positions derived from photographic observations of both passive and active satellites and from range observations. The current status of data analysis, processing and results are examined

    Clinical Manifestations of Hereditary Hemorrhagic Telangiectasia

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72156/1/j.1572-0241.1984.tb05137.x.pd

    Readout of solid-state charge qubits using a single-electron pump

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    A major difficulty in realizing a solid-state quantum computer is the reliable measurement of the states of the quantum registers. In this paper, we propose an efficient readout scheme making use of the resonant tunneling of a ballistic electron produced by a single electron pump. We treat the measurement interaction in detail by modeling the full spatial configuration, and show that for pumped electrons with suitably chosen energy the transmission coefficient is very sensitive to the qubit state. We further show that by using a short sequence of pumping events, coupled with a simple feedback control procedure, the qubit can be measured with high accuracy.Comment: 5 pages, revtex4, 4 eps figures. v2: published versio

    Charge sensing in carbon nanotube quantum dots on microsecond timescales

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    We report fast, simultaneous charge sensing and transport measurements of gate-defined carbon nanotube quantum dots. Aluminum radio frequency single electron transistors (rf-SETs) capacitively coupled to the nanotube dot provide single-electron charge sensing on microsecond timescales. Simultaneously, rf reflectometry allows fast measurement of transport through the nanotube dot. Charge stability diagrams for the nanotube dot in the Coulomb blockade regime show extended Coulomb diamonds into the high-bias regime, as well as even-odd filling effects, revealed in charge sensing data.Comment: 4 pages, 4 figure
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