Alien Registration- Ducharme, Edwin A. (Lewiston, Androscoggin County)

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Gas exchange, δ13C, and heterotrophy for Castilleja linariifolia and Orthocarpus tolmiei, facultative root hemiparasites on Artemisia tridentata

Journal ArticleGas exchange and carbon isotope ratios were measured on 2 facultative hemiparasites, Castilleja linarifolia Benth. (Indian paintbrush; Scrophulariaceae) and Orthocarpus tolmiei I-I. & A. (Tolmie owl clover; Scrophulariaceae), and their Artemisia tridentata L. (big sagebrush; Asteraceae) hosts. Photosynthetic rates differed greatly between years; rates in 1995 were more than double those in 1994, likely due to more precipitation and less water stress during 1995. Despite this difference in precipitation, photosynthetic rates for C. linariifolia were not different from those of their hosts for either year. However, carbon isotope ratios of C. linariifolia and O. tolmiei were up to 30/00 more negative than those of their A. tridentata hosts. Using measured δ13C ratios in conjunction with δ13C ratios predicted from gas-exchange measurements, we calculated that C. linariifolia derived, on average, 40% of its leaf carbon heterotrophically. Contrary to current suggestions that high photosynthetic rates of hemiparasites are an indication of reduced heterotrophy, C. linariifolia exhibited photosynthetic rates similar to autotrophic plants and used a substantial amount of host-derived carbon. Moreover, this evidence shows that manipulation of a heterotrophic carbon supply transcends obligate hemiparasites to include those plants whose parasitism is facultative

Fractional Angular Momenta, Gouy and Berry Phases in Relativistic Bateman-Hillion-Gaussian Beams of Electrons

A new Bateman-Hillion solution to the Dirac equation for a relativistic Gaussian electron beam taking explicit account of the four-position of the beam waist is presented. This solution has a pure Gaussian form in the paraxial limit but beyond it contains higher order Laguerre-Gaussian components attributable to the tighter focusing. One implication of the mixed mode nature of strongly diffracting beams is that the expectation values for spin and orbital angular momenta are fractional and are interrelated to each other by intrinsic spin-orbit coupling. Our results for these properties align with earlier work on Bessel beams [Bliokh et al., Phys. Rev. Lett. 107, 174802 (2011)] and show that fractional angular momenta can be expressed by means of a Berry phase. The most significant difference arises, though, due to the fact that Laguerre-Gaussian beams naturally contain Gouy phase, while Bessel beams do not. We show that Gouy phase is also related to Berry phase and that Gouy phase fronts that are flat in the paraxial limit become curved beyond it

Manifestation of a Ferroelectric Phase Transition

Temperature dependences of the dielectric properties of ultrathin polyvinylidene fluoride films prepared using the Langmuir-Blodgett method were studied by linear and nonlinear dielectric spectroscopy. It is shown that ultrathin Langmuir films of polyvinylidene fluoride exhibit a manifestation of a first-order ferroelectric phase transition, which can be assigned to the interaction between the spontaneous polarization and the surfaces bounding the film. As the film thickness increases, the effect of the surfaces decreases and the ferroelectric phase transition shifts to high temperatures to vanish altogether when the temperature region of the transition rises above the melting point

L’impact de la technologie informatique sur la main-d’oeuvre dans les organisations

Comment les dirigeants des entreprises québécoises perçoivent-ils les impacts de la technologie informatique sur la main-d’oeuvre dans leurs propres organisations? Nous exposons dans le cadre de cet article les résultats partiels d’une étude empirique à laquelle plus de 1 700 dirigeants ont participé. Cette recherche se situe donc dans une perspective strictement organisationnelle et non pas macro-économique. Les présents résultats indiquent que la taille mais non le secteur d’activité de l’entreprise, serait un facteur significatif à considérer lors de l’étude des variations du nombre d’emplois et de la productivité dans une organisation. De plus, il existerait des différences importantes selon les catégories d’employés.What is the impact of information technology on human resources in organizations as percieved by managers? This article provides empirical results from a survey of 1,708 organizations. The results indicate that firm size is a significant variable influencing the impact of technology on the number and productivity of employees. Futhermore, different categories of employees are affected differently

L’impact de la technologie informatique sur la main-d’oeuvre dans les organisations

What is the impact of information technology on human resources in organizations as percieved by managers? This article provides empirical results from a survey of 1,708 organizations. The results indicate that firm size is a significant variable influencing the impact of technology on the number and productivity of employees. Futhermore, different categories of employees are affected differently. Comment les dirigeants des entreprises québécoises perçoivent-ils les impacts de la technologie informatique sur la main-d’oeuvre dans leurs propres organisations? Nous exposons dans le cadre de cet article les résultats partiels d’une étude empirique à laquelle plus de 1 700 dirigeants ont participé. Cette recherche se situe donc dans une perspective strictement organisationnelle et non pas macro-économique. Les présents résultats indiquent que la taille mais non le secteur d’activité de l’entreprise, serait un facteur significatif à considérer lors de l’étude des variations du nombre d’emplois et de la productivité dans une organisation. De plus, il existerait des différences importantes selon les catégories d’employés.

Ellipsometer

In an ellipsometer, a phase-modulated, polarized light beam is applied to a sample, electrical signals are obtained representing the orthogonal planes of polarization of the light after it has interacted with the sample and the constants of the sample are calculated from the two resulting electrical signals. The phase modulation is sufficiently small so that the calibration errors are negligible. For this purpose, the phase modulator, phase modulates the light within a range of no more than ten degrees peak to peak. The two electrical signals are expanded by Fourier analysis and the coefficients thereof utilized to calculate psi and delta

Investigation of state retention in metal–ferroelectric–insulator–semiconductor structures based on Langmuir–Blodgett copolymer films

Among the ferroelectric thin films considered for use in nonvolatile memory devices, the ferroelectric copolymer of polyvinylidene fluoride, PVDF (C2H2F2), with trifluoroethylene, TrFE (C2HF3), has distinct advantages, including low dielectric constant, low processing temperature, relative low cost compared with epitaxial ferroelectric oxides, and compatibility with organic semiconductors. We report the operation and polarization retention properties of a metal– ferroelectric–insulator–semiconductor bistable capacitor memory element consisting of an aluminum gate, a P(VDF-TrFE) Langmuir–Blodgett film, a 30 nm cerium oxide buffer layer, and a moderately doped silicon wafer. The device exhibited a 1.9 V wide hysteresis window obtained with a +/-7 V operating range with a state retention time of 10 min. The mechanisms contributing to loss of state retention are discussed

Optical second harmonic generation probe of two-dimensional ferroelectricity

Optical second harmonic generation (SHG) is used as a noninvasive probe of two-dimensional (2D) ferroelectricity in Langmuir-Blodgett (LB) films of copolymer vinylidene fluoride with trifluorethylene. The surface 2D ferroelectric-paraelectric phase transition in the topmost layer of LB films and a thickness independent (almost 2D) transition in the bulk of these films are observed in temperature studies of SHG.Comment: 9 pages, 2 figures, Optics Letters, in prin