9,397 research outputs found
Substrate effects on surface magetetism of Fe/W(110) from first principles
Surface magnetic properties of the pseudomorphic Fe(110) monolayer on a
W(110) substrate are investigated from first principles as a function of the
substrate thickness (up to eight layers). Analyzing the magnetocrystalline
anisotropy energies, we find stable (with respect to the number of substrate
layers) in-plane easy and hard axes of magnetization along the [1[overline 1]0]
and [001] directions, respectively, reaching a value in good agreement with
experiment for thick substrates. Additionally, the changes to the magnetic spin
moments and the density of the Fe d states are analyzed with respect to the
number of substrate layers as well as with respect to the direction of
magnetization. With respect to the number of W(110) substrate layers beneath
the Fe(110) surface, we find that the first four substrate layers have a large
influence on the electronic and magnetic properties of the surface. Beyond the
fourth layer, the substrate has only marginal influence on the surface
properties.Comment: 8 Pages, 3 Figures, 3 Table
Scanning Photo-Induced Impedance Microscopy - Resolution studies and polymer characterization
Scanning Photo-Induced Impedance Microscopy (SPIM) is an impedance imaging technique that is based on photocurrent measurements at field-effect structures. The material under investigation is deposited onto a semiconductor-insulator substrate. A thin metal film or an electrolyte solution with an immersed electrode serves as the gate contact. A modulated light beam focused into the space charge region of the semiconductor produces a photocurrent, which is directly related to the local impedance of the material. The absolute impedance of a polymer film can be measured by calibrating photocurrents using a known impedance in series with the sample. Depending on the wavelength of light used, charge carriers are not only generated in the focus but also throughout the bulk of the semiconductor. This can have adverse effects on the lateral resolution. Two-photon experiments were carried out to confine charge carrier generation to the spacecharge layer. The lateral resolution of SPIM is also limited by the lateral diffusion of charge carriers in the semiconductor. This problem can be solved by using thin silicon layers as semiconductor substrates. A resolution of better than 1 mu m was achieved using silicon on sapphire (SOS) substrates with a I l.Lm thick silicon layer
The Financial Collapse Of The Milwaukee Public Museum
The 123-year old Milwaukee Public Museum, which had long been considered to be one of the top natural history museums in the country, found itself in dire financial straights in 2005. The museum had run large deficits for the past three years and had almost entirely eaten through its cash and long-term endowment. In June 2005 it was forced to lay off many of its experienced collections and research staff and had begun the process of preparing to sell off assets that were not a part of the “exhibit experience.” Milwaukee County’s Chief Executive went so far as to suggest that the Museum’s celebrated 700-acre Tirimbina rain forest preserve in Costa Rica should be sold. How did this once renowned organization become a shell of its former self? What financial management and governance mistakes were made, if any, and how could this disaster have been prevented
The Enamel Ultrastructure of Multituberculate Mammals: A Review
The enamel ultrastructure of multituberculate mammals has been sampled extensively and studied intensively and is better known than for any other group of early mammals. The enamel of the earliest multituberculates, those of the Late Triassic-Early Jurassic suborder Haramiyoidea and the Late Jurassic-early Early Cretaceous suborder Plagiaulacoidea, is preprismatic. With only two exceptions, all Late Cretaceous and early Tertiary genera of multituberculates examined have prismatic enamel. Prisms are either small with circular (complete) boundaries or large with arc-shaped (incomplete) boundaries. There is a remarkably consistent relationship between enamel ultrastructural type and subordinal taxa in that small, circular prisms are usually found within the suborder Ptilodontoidea and large, arc-shaped prisms are usually found in the suborder Taeniolabidoidea and in six Late Cretaceous-Early Tertiary genera of indeterminate subordinal status.
Research currently in progress suggests that both small, circular prisms and large, arc-shaped prisms are homologous in all multituberculates in which they occur, with one exception. Neoliotomus, a taeniolabidoid, appears to have evolved small, circular prisms independently. In addition, it appears that large, arc-shaped prisms represent the primitive condition in multituberculates with prismatic enamel, not small, circular prisms as has been proposed previously
The Diminishing Benefits Of Nae International Portfolio Diversification Following The 1997 Asian Financial Crisis
Nae international diversification has been fundamental to portfolio management over the past 30 years, but the benefits appear to be significantly diminished following the 1997 Asian financial crisis. Using monthly return data covering the period from 1970 through 2004, we found rising correlations between U.S. and international equity markets exceeding 0.85 since July 1997. Even the return correlation of emerging countries recently has reached almost 0.80. We also found a significant reduction in the variance of the international return correlation after the financial crisis. Portfolio managers should not expect to receive the same benefits from international portfolio diversification as that obtained prior to the Asian financial crisis
Multituberculates (Mammalia, Allotheria) From The Earliest Tiffanian (Late Paleocene) Douglass Quarry, Eastern Crazy Mountains Basin, Montana
http://deepblue.lib.umich.edu/bitstream/2027.42/49355/1/Vol 31 No10 final 11-15-06.pd
LAPS and SPIM Imaging Using ITO-Coated Glass as the Substrate Material
Light-addressable
potentiometric sensors (LAPS) and scanning photo-induced
impedance microscopy (SPIM) use photocurrent measurements for spatiotemporal
imaging of ion concentrations, electrical potentials, and impedance.
In this work, ITO-coated glass was confirmed to produce photocurrents
at anodic potentials with 405 nm diode laser illumination. Therefore,
it was developed as a low cost and robust substrate material for LAPS
and SPIM imaging compared to traditional expensive ultrathin Si substrates.
ITO showed good ac photocurrent and pH response without surface modification
and insulator. Local photocurrents were produced by scanning a focused
laser beam across the sample, which proved the light addressability
of ITO-coated glass. With a high-impedance PMMA dot deposited onto
the ITO as a model system, a lateral resolution of about 2.3 μm
was achieved
Measurement of the Casimir force between dissimilar metals
The first precise measurement of the Casimir force between dissimilar metals
is reported. The attractive force, between a Cu layer evaporated on a
microelectromechanical torsional oscillator, and an Au layer deposited on an
AlO sphere, was measured dynamically with a noise level of 6
fN/. Measurements were performed for separations in the 0.2-2
m range. The results agree to better than 1% in the 0.2-0.5 m range
with a theoretical model that takes into account the finite conductivity and
roughness of the two metals. The observed discrepancies, which are much larger
than the experimental precision, can be attributed to a lack of a complete
characterization of the optical properties of the specific samples used in the
experiment.Comment: 6 pages, 4 figure
Measurement of the Permanent Electric Dipole Moment of the Xe Atom
We report on a new measurement of the CP-violating permanent Electric Dipole
Moment (EDM) of the neutral Xe atom. Our experimental approach is based
on the detection of the free precession of co-located nuclear spin-polarized
He and Xe samples. The EDM measurement sensitivity benefits
strongly from long spin coherence times of several hours achieved in diluted
gases and homogeneous weak magnetic fields of about 400~nT. A finite EDM is
indicated by a change in the precession frequency, as an electric field is
periodically reversed with respect to the magnetic guiding field. Our result,
ecm, is consistent with zero and is
used to place a new upper limit on the Xe EDM: ecm (95% C.L.). We also discuss the implications of this result for
various CP-violating observables as they relate to theories of physics beyond
the standard model
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