5,792 research outputs found
The Effect of Transfer Printing on Pentacene Thin-Film Crystal Structure
The thermal deposition and transfer Printing method had been used to produce
pentacene thin-films on SiO2/Si and plastic substrates (PMMA and PVP),
respectively. X-ray diffraction patterns of pentacene thin films showed
reflections associated with highly ordered polycrystalline films and a
coexistence of two polymorph phases classified by their d-spacing, d(001): 14.4
and 15.4 A.The dependence of the c-axis correlation length and the phase
fraction on the film thickness and printing temperature were measured. A
transition from the 15.4 A phase towards 14.4 A phase was also observed with
increasing film thickness. An increase in the c-axis correlation length of
approximately 12% ~16% was observed for Pn films transfer printed onto a PMMA
coated PET substrate at 100~120 C as compared to as-grown Pn films on SiO2/Si
substrates. The transfer printing method is shown to be an attractive for the
fabrication of pentacene thin-film transistors on flexible substrates partly
because of the resulting improvement in the quality of the pentacene film.Comment: 5 pages, 5 figure
The Polarized Spectrum of Apm 08279+5255
We report the discovery of significant linear polarization (p > 1%) in the
hyperluminous z=3.87 BALQSO APM~08279+5255. The polarization spectrum is
complex, with properties similar to those of other, lower redshift but more
highly polarized BALQSOs. The resonance emission lines are unpolarized while
the absorption troughs show polarization similar to or higher than the
continuum. In particular, an apparent increase of polarization in the trough
covering 1000-1030 angstroms (rest) supports the interpretation of this feature
as a broad absorption component associated with OVI/Ly_beta local to the QSO,
as opposed to an intervening damped Ly_alpha absorption system.
The elevated polarization in some of the absorption features implies that we
view the scattered (polarized) spectrum through a sightline with less absorbing
material than the direct spectrum. Therefore, the complex structure of the
polarization spectrum in this brilliant lensed BALQSO suggests that it will be
an important laboratory for studying the structure of QSOs at high redshift.Comment: 8 pages, 1 figure. Accepted for publication in The Astrophysical
Journal Letter
Understanding the AMT, and its Unadopted Sibling, the AMxT
Four million Americans with extensive tax preferences are subject to the Alternative Minimum Tax (AMT). By taxing a broad definition of income, the AMT makes it possible to have a tax system that both encourages certain activities with generous tax preferences and maintains a semblance of distributional equity. The same rationale supports the imposition of an Alternative Maximum Tax (AMxT), which would cap tax liabilities of individuals with very few preference items and thereby afford Congress greater flexibility in designing the income tax. The original 1969 AMT proposal included an AMxT; it is difficult to justify imposing one without the other
Delegating Tax
Congress delegates extensive and growing lawmaking authority to federal administrative agencies in areas other than taxation, but tightly limits the scope of Internal Revenue Service (IRS) and Treasury regulatory discretion in the tax area, specifically not permitting these agencies to select or adjust tax rates. This Article questions why tax policy does and should differ from other policy areas in this respect, noting some of the potential policy benefits of delegation. Greater delegation of tax lawmaking authority would allow administrative agencies to apply their expertise to fiscal policy and afford timely adjustment to changing economic circumstances. Furthermore, delegation of the tax reform process to an independent commission or agency offers the prospect of Congress committing itself to rational reform and long-run budget sustainability in a way that is more apt to succeed than piecemeal legislative efforts. The Article concludes with an analysis of the constitutionality of tax delegation, noting the applicability of recent Supreme Court decisions confirming Congressâs broad discretion to delegate rulemaking authority to federal agencies, and arguing that tax policy is of a kind with other federal policies
An Extraordinary Scattered Broad Emission Line in a Type 2 QSO
An infrared-selected, narrow-line QSO has been found to exhibit an
extraordinarily broad Halpha emission line in polarized light. Both the extreme
width (35,000 km/sec full-width at zero intensity) and 3,000 km/sec redshift of
the line centroid with respect to the systemic velocity suggest emission in a
deep gravitational potential. An extremely red polarized continuum and partial
scattering of the narrow lines at a position angle common to the broad-line
emission imply extensive obscuration, with few unimpeded lines of sight to the
nucleus.Comment: 4 pages, 1 figure, to appear in the Astrophysical Journal Letter
Performance of statistical energy analysis
Statistical energy analysis (SEA) methods have been developed for high frequency modal analyses on random vibration environments. These SEA methods are evaluated by comparing analytical predictions to test results. Simple test methods are developed for establishing SEA parameter values. Techniques are presented, based on the comparison of the predictions with test values, for estimating SEA accuracy as a function of frequency for a general structure
Neuron splitting in compute-bound parallel network simulations enables runtime scaling with twice as many processors
Neuron tree topology equations can be split into two subtrees and solved on different processors with no change in accuracy, stability, or computational effort; communication costs involve only sending and receiving two double precision values by each subtree at each time step. Splitting cells is useful in attaining load balance in neural network simulations, especially when there is a wide range of cell sizes and the number of cells is about the same as the number of processors. For compute-bound simulations load balance results in almost ideal runtime scaling. Application of the cell splitting method to two published network models exhibits good runtime scaling on twice as many processors as could be effectively used with whole-cell balancing
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