3,762 research outputs found

    Complex permeability of soft magnetic ferrite polyester resin composites at frequencies above 1 MHz

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    Composite soft magnetic materials consist of magnetic particles in a non-magnetic matrix. The properties of such materials can be modelled using effective medium theory. Measurements have been made of the complex permeability of composites produced using ferrite powder and polyester resin. The success of various effective medium expressions in predicting the variation of complex permeability with composition has been assessed

    Relationships Among Foliar Phenology, Radial Growth Rate, and Xylem Density in a Young Douglas-Fir Plantation

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    We related intra-annual patterns in radial growth rate and xylem density to foliar phenology and second growth flushes in a young Douglas-fir plantation in western Washington. Three foliar maturity classes were defined: (1) shoots and needles elongating; (2) elongation complete, needles maturing; and (3) needles mature. Diameter growth rate had two peaks, one about the time of budbreak and one when foliage was in maturity Class 2. There was a limit to the maximum periodic density of xylem formed at a given rate of diameter growth; as growth rate increased, maximum periodic density decreased. Although xylem density profiles varied widely among individual trees, xylem density differed significantly among foliar maturity classes, increasing 16% from Class 1 to 2 and 60% from Class 2 to 3. Diameter growth rate of second-flushing trees was significantly greater in July compared with trees with no second flush, but we detected no relationships between second-flushing and xylem density patterns or false rings. Although the young trees in this study did not show distinct earlywood-latewood transitions, fully mature foliage (Class 3) was associated with formation of xylem exhibiting characteristics of latewood: greater density, reduced diameter growth rate, reduced tracheid radial diameter, and less interannual growth variation

    Unhousing the Urban Poor: The Reagan Legacy

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    The Reagan era was characterized by the popularity of individual level explanations and market based solutions for a range of social problems, including homelessness. We argue that such an approach was inadequate and may, in fact, have toorsened the housing situation. We claim that homelessness is fundamentally a housing problem linked to two key trends of the 1980s: the increasing rate of poverty and the declining supply\u27f low-income housing. Market approaches to housing policy have resulted in housing policies by default: gentrification, condo conversion and displacement as well as tax policies that explicitly favor the nonpoor. Those policies gehred towards the poor, vouchers and subsidies, were inadequate responses to increasing need. In sum, the Reagan years witnessed dramatic declines in the supply of low-cost housing, substantial increases in the poverty rate, and drastic shifts in federal policy towards housing the poor

    Spin-forbidden carbon–carbon bond formation in vibrationally excited α-CO

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    Fourier transform infrared spectroscopy of laser-irradiated cryogenic crystals shows that vibrational excitation of CO leads to the production of equal amounts of CO2 and C3O2. The reaction mechanism is explored using electronic structure calculations, demonstrating that the lowest-energy pathway involves a spin-forbidden reaction of (CO)2 yielding C(3P) + CO2. C(3P) then undergoes barrierless recombination with two other CO molecules forming C3O2. Calculated intersystem crossing rates support the spin-forbidden mechanism, showing subpicosecond spin-flipping time scales for a (CO)2 geometry that is energetically consistent with states accessed through vibrational energy pooling. This spin-flip occurs with an estimated ∼4% efficiency; on the singlet surface, (CO)2 reconverts back to CO monomers, releasing heat which induces CO desorption. The discovery that vibrational excitation of condensed-phase CO leads to spin-forbidden C−C bond formation may be important to the development of accurate models of interstellar chemistry

    Research notes: Aluminum tolerance in soybean germplasm

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    Aluminum in the soil solution is a severe growth limiting factor in certain acid soils (Foy, 1964; Long and Foy, 1970). This problem is particularly serious in acid subsoils (Adams and Lund, 1966; Foy, 1964) which are difficult to lime. Recent research has centered on selecting those plant cultivars which demonstrate a degree of tolerance to soil aluminum

    Data supporting development and validation of liquid chromatography tandem mass spectrometry method for the quantitative determination of bile acids in feces

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    Measuring bile acids in feces has an important role in disease prevention, diagnosis, treatment, and can be considered a measure of health status. Therefore, the primary aim was to develop a sensitive, robust, and high throughput liquid chromatography tandem mass spectrometry method with minimal sample preparation for quantitative determination of bile acids in human feces applicable to large cohorts. Due to the chemical diversity of bile acids, their wide concentration range in feces, and the complexity of feces itself, developing a sensitive and selective analytical method for bile acids is challenging. A simple extraction method using methanol suitable for subsequent quantification by liquid chromatography tandem mass spectrometry has been reported in, “Extraction and quantitative determination of bile acids in feces” [1]. The data highlight the importance of optimization of the extraction procedure and the stability of the bile acids in feces post-extraction and prior to analysis and after several freeze-thaw cycles

    Electron-deuteron scattering in the equal-time formalism: beyond the impulse approximation

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    Using a three-dimensional formalism that includes relativistic kinematics, the effects of negative-energy states, approximate boosts of the two-body system, and current conservation, we calculate the electromagnetic form factors of the deuteron up to Q^2 of 4 GeV^2. This is done using a dynamical boost for two-body systems with spin. We first compute form factors in impulse approxmation, but then also add an isoscalar meson-exchange current of pion range that involves the gamma-pi contact operator associated with pseudovector pi-N coupling. We also consider effects of the rho-pi-gamma meson-exchange current. The experimentally measured quantities A, B, and t20 are calculated over the kinematic range probed in recent Jefferson Laboratory experiments. The rho-pi-gamma meson-exchange current provides significant strength in A at large Q^2 and the gamma-pi contact-term exchange current shifts t20, providing good agreement with the JLab data. Relativistic effects and the gamma-pi meson-exchange current do not provide an explanation of the B observable, but the rho-pi-gamma current could help to provide agreement if a nonstandard value is used for the tensor rho-N coupling that enters this contribution.Comment: 15 pages, 10 figures. (v2) Added references on rho-pi-gamma current as well as comparison to recent Novosibirsk data on T20. Implemented \includegraphics in place of \BoxedEPSF. (v3) Modified in order to clarify the nature of the boost we implemented for particles with spin. Other minor changes. Version to be published in Physical Review

    Magnescope: Applications in nondestructive evaluation

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    This paper describes recent results obtained with the Magnescope, which has been used on location in industrial environments and has successfully detected impending fatigue failure, creep damage, applied stress, and microstructural differences. It is concluded that the device provides a useful nondestructive method for evaluating the mechanical properties of materials through the measurement of their structure sensitive magnetic properties

    Oxo-aglaiastatin-mediated inhibition of translation initiation

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    We thank Dr. Elias George (McGill University) for the kind gift of Pgp-1-expressing HeLa cells. RIM was supported by a doctoral fellowship from the Cole Foundation. This research was supported by a grant from the Canadian Institutes of Health Research (FDN-148366) to JP. J.A.P., Jr. is supported by NIH Grant R35 GM118173. Work at the Boston University Center for Molecular Discovery is supported by Grant R24 GM111625. (Cole Foundation; FDN-148366 - Canadian Institutes of Health Research; R35 GM118173 - NIH; R24 GM111625)Published versionSupporting documentatio
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