16,364 research outputs found

    Spectral Energy Distributions of Passive T Tauri Disks: Inclination

    Get PDF
    We compute spectral energy distributions (SEDs) for passive T Tauri disks viewed at arbitrary inclinations. Semi-analytic models of disks in radiative and hydrostatic equilibrium are employed. Over viewing angles for which the flared disk does not occult the central star, the SED varies negligibly with inclination. For such aspects, the SED shortward of ~80 microns is particularly insensitive to orientation, since short wavelength disk emission is dominated by superheated surface layers which are optically thin. The SED of a nearly edge-on disk is that of a class I source. The outer disk occults inner disk regions, and emission shortward of ~30 microns is dramatically extinguished. Spectral features from dust grains may appear in absorption. However, millimeter wavelength fluxes decrease by at most a factor of 2 from face-on to edge-on orientations. We present illustrative applications of our SED models. The class I source 04108+2803B is considered a T Tauri star hidden from view by an inclined circumstellar disk. Fits to its observed SED yield model-dependent values for the disk mass of ~0.015 solar masses and a disk inclination of ~65 degrees relative to face-on. The class II source GM Aur represents a T Tauri star unobscured by its circumstellar disk. Fitted parameters include a disk mass of \~0.050 solar masses and an inclination of ~60 degrees.Comment: Accepted to ApJ, 20 pages, 7 figures, aaspp4.st

    Phase analysis of the cosmic microwave background from an incomplete sky coverage

    Full text link
    Phases of the spherical harmonic analysis of full-sky cosmic microwave background (CMB) temperature data contain useful information complementary to the ubiquitous angular power spectrum. In this letter we present a new method of phase analysis on incomplete sky maps. It is based on Fourier phases of equal-latitude pixel rings of the map, which are related to the mean angle of the trigonometric moments from the full-sky phases. They have an advantage for probing regions of interest without tapping polluted Galactic plane area, and can localize non-Gaussian features and departure from statistical isotropy in the CMB.Comment: 5 pages, 3 figures submitted to MNRAS Letters, replaced with minor change

    A theoretical study of heterojunction and graded band gap type solar cells

    Get PDF
    The work performed concentrated on including multisun effects, high temperature effects, and electron irradiation effects into the computer analysis program for heterojunction and graded bandgap solar cells. These objectives were accomplished and the program is now available for such calculations

    The Impact of U.S. Trade Law on Government Policy Making in the Republic of China

    Get PDF
    Since President Reagan signed the Omnibus Trade Act on August 23, 1988, the U.S. government has completed a series of investigations according to the provisions of the Act. Consultations aimed at forcing its trading partners to adjust their trade- policies which are regarded as unfair to U.S. trade have also been held in the past ten months or so. Being one of the most important trading partners of the U.S. – both in terms of its overall trade volume and its surplus with the U.S. – the Republic of China on Taiwan (ROC) seems to have become a target of retaliatory measures implied in the Act. During the period from August of last year to this date, the U.S. has consulted intensively with the ROC on various trade issues. The possible implementation of the Trade Act seemed to have been implied throughout most of the talks. Therefore, the results of consultations often had an impact on the trade policy of the ROC. On the other hand, the adjustments that the ROC has made to cope with the new environment of the world economy have also been instrumental in formulating the ROC\u27s new trade policy. All in all, the ROC\u27s trade policy has been transformed, over the past twenty-five years, from an export-oriented one to the present one which encourages imports with a view toward balancing the two-way trade. In order to carry out this policy, the ROC has adopted a series of measures not only to expedite the liberalization of its market, but also to increase its purchases from the U.S

    Lepton Flavor Violating Radiative Decays in EW-Scale νR\nu_R Model: An Update

    Get PDF
    We perform an updated analysis for the one-loop induced lepton flavor violating radiative decays li→ljγl_i \to l_j \gamma in an extended mirror model. Mixing effects of the neutrinos and charged leptons constructed with a horizontal A4A_4 symmetry are also taken into account. Current experimental limit and projected sensitivity on the branching ratio of μ→eγ\mu \to e \gamma are used to constrain the parameter space of the model. Calculations of two related observables, the electric and magnetic dipole moments of the leptons, are included. Implications concerning the possible detection of mirror leptons at the LHC and the ILC are also discussed.Comment: 9 figures, 36 single-side pages. Updated email addresses and referenc

    The Influence of Federal Laboratory R&D on Industrial Research

    Get PDF
    Over the past 60 years the United States has created the world's largest system of government laboratories. The impact of the laboratories on the private economy has been little studied though their research accounts for 14% of total U.S. R&D, more than the R&D of all colleges and universities combined. In this paper we study the influence of federal laboratory R&D on industrial research using a sample of industrial laboratories. In head-to-head comparisons with alternative measures, we find that Cooperative Research and Development Agreements or CRADAs, are the primary channel by which federal laboratories increase the patenting and R&D of industrial laboratories. With a CRADA industrial laboratories patent more, spend more on company-financed R&D and spend more of their own money on federal laboratories. Without a CRADA patenting stays about the same and only federally funded R&D increases, mostly because of direct subsidies by government. These results are consistent with the literature on endogenous R&D spillovers, which emphasizes that knowledge spills over when recipients work at making it spill over. CRADAs are legal agreements between federal laboratories and firms to work together on joint research. They are backed by real budgets and accompanied by cost sharing that could bind the parties together in joint research. Moreover, the CRADA instrument is the main form of such agreements. Thus, both in theory and in fact CRADAs may be more beneficial to firms than other public- private interactions, precisely because of the mutual effort that they require of firms and government laboratories.

    The Influence of Federal Laboratory R&D on Industrial Research

    Get PDF
    This paper studies the influence of R&D in the federal laboratory system, the world's largest, on firm research. Our results are based on a sample of 220 industrial research laboratories that work with a variety of federal laboratories and agencies and are owned by 115 firms in the chemicals, machinery, electrical equipment, and motor vehicles industries. Using an indicator of their importance to R&D managers, we find that Cooperative Research and Development Agreements or CRADAs dominate other channels of technology transfer from federal laboratories to firms. With a CRADA industry laboratories patent more, spend more on company-financed R&D, and devote more resources to their federal counterparts. Without this influence patenting stays about the same, and only federally funded R&D increases, mostly because of government support. The Stevenson-Wydler Act and amendments during the 1980s introduced CRADAs, which legally bind federal laboratories and firms together in joint research. In theory the agreements could capitalize on complementarities between public and private research. Our results support this perspective and suggest that CRADAs may be more beneficial to firms than other interactions with federal laboratories, precisely because of the mutual effort that they demand from both parties.
    • …
    corecore