27,605 research outputs found
Error estimates for interpolation of rough data using the scattered shifts of a radial basis function
The error between appropriately smooth functions and their radial basis
function interpolants, as the interpolation points fill out a bounded domain in
R^d, is a well studied artifact. In all of these cases, the analysis takes
place in a natural function space dictated by the choice of radial basis
function -- the native space. The native space contains functions possessing a
certain amount of smoothness. This paper establishes error estimates when the
function being interpolated is conspicuously rough.Comment: 12 page
Latent image diffraction from submicron photoresist gratings
Light scattering from latent images in photoresist is useful for lithographic tool characterization, process monitoring, and process control. In particular, closed‐loop control of lithographic processes is critical for high yield, low cost device manufacturing. In this work, we report use of pulsed laser diffraction from photoresist latent images in 0.24 μm pitch distributed feedback laser gratings. Gated detection of pulsed light scattering permits high spatial resolution probing using ultraviolet light without altering the latent image. A correlation between latent image and etched grating diffraction efficiencies is demonstrated and shows the value of "upstream" monitoring
New Hamiltonian formalism and quasi-local conservation equations of general relativity
I describe the Einstein's gravitation of 3+1 dimensional spacetimes using the
(2,2) formalism without assuming isometries. In this formalism, quasi-local
energy, linear momentum, and angular momentum are identified from the four
Einstein's equations of the divergence-type, and are expressed geometrically in
terms of the area of a two-surface and a pair of null vector fields on that
surface. The associated quasi-local balance equations are spelled out, and the
corresponding fluxes are found to assume the canonical form of energy-momentum
flux as in standard field theories. The remaining non-divergence-type
Einstein's equations turn out to be the Hamilton's equations of motion, which
are derivable from the {\it non-vanishing} Hamiltonian by the variational
principle. The Hamilton's equations are the evolution equations along the
out-going null geodesic whose {\it affine} parameter serves as the time
function. In the asymptotic region of asymptotically flat spacetimes, it is
shown that the quasi-local quantities reduce to the Bondi energy, linear
momentum, and angular momentum, and the corresponding fluxes become the Bondi
fluxes. The quasi-local angular momentum turns out to be zero for any
two-surface in the flat Minkowski spacetime. I also present a candidate for
quasi-local {\it rotational} energy which agrees with the Carter's constant in
the asymptotic region of the Kerr spacetime. Finally, a simple relation between
energy-flux and angular momentum-flux of a generic gravitational radiation is
discussed, whose existence reflects the fact that energy-flux always
accompanies angular momentum-flux unless the flux is an s-wave.Comment: 36 pages, 3 figures, RevTex
Photoluminescence from Si nanocrystals exposed to a hydrogen plasma
Si nanocrystals embedded in SiO₂films were exposed to an atomic H plasma at different temperatures. Photoluminescence intensity from the nanocrystals increases with increasing exposure time, followed by saturation that depends on the exposure temperature. The saturation level depends on the final exposure temperature and shows no dependence on the thermal history of exposure. This behavior is shown to be consistent with a model in which the steady-state passivation level is determined by a balance between defect passivation and depassivation by H, with the activation energy for the passivationreaction being larger than that for the depassivation reaction.This work was supported by Research Institute for Basic
Science at Kangwon National University
Does noncommutative geometry predict nonlinear Higgs mechanism?
It is argued that the noncommutative geometry construction of the standard
model predicts a nonlinear symmetry breaking mechanism rather than the orthodox
Higgs mechanism. Such models have experimentally verifiable consequences.Comment: 12 pages, LaTeX file, BI-TP 93/2
An eigenmode analysis of time delays in an acoustically coupled multi-bubble system
The acoustic properties of an inhomogeneous bubbly medium are complex owing to the absorption and re-emission of acoustic energy by the bubbles. This phenomena can be approximated by a globally coupled system of linear oscillators. In previous studies, it has been shown that this simple model can produce results that are in qualitative agreement with experimental data. In order to achieve better quantitative agreement with experimental data, time-delays need to be introduced into the mathematical model. In the present study, the resulting delayed differential equations were solved numerically using a 4th order Runge-Kutta method. The numerical methodology was validated by comparing simplified cases with the solution using analytical methods. The effects of time-delay were assessed by comparing non-timedelayed and time-delayed versions of the mathematical model. Results from numerical simulations were then compared to assess the effects and importance of the inclusion of time-delay in the mathematical model. This study shows that the inclusion of time-delay has a noticeable effect on the lower frequency modes of the model. This effect propagates to the higher frequency modes as the magnitude of the time-delay increases. The results also shows that the time-delay shifts the dominant modes from the lower frequency modes to the higher frequency mode
Persistent amygdala novelty response is associated with less anterior cingulum integrity in trauma-exposed women
Objectives: We investigated the potential role of cingulum and uncinate fasciculus integrity in trauma-related neural hypervigilance, indexed by less discrimination between amygdala activation to novel and familiar affective images.
Participants: 22 women (mean age 21.7 ± 3.9 years) with a history of trauma, and 20 no-trauma controls (mean age 21.9 ± 4.8 years).
Measures: Trauma exposure and trauma-related symptoms were assessed during structured clinical interview. White matter integrity in the anterior cingulum, parahippocampal cingulum, and uncinate fasciculus was measured using diffusion weighted imaging. Amygdala response to novel and familiar affective scenes was measured with functional magnetic resonance imaging.
Results: Trauma-exposed women showed less discrimination between novel and familiar negative images in the amygdala compared to no-trauma controls. In trauma-exposed women, less amygdala discrimination between novel and familiar affective images was associated with less structural integrity in the anterior cingulum, but was not associated with structural integrity of the parahippocampal cingulum or the uncinate fasciculus.
Conclusions: The anterior cingulum might play an important role in impaired novelty discrimination for affective information in the amygdala. This impairment is potentially driven by inefficient habituation and could contribute to persistent behavioral hypervigilance following trauma exposure
Nano granular metallic Fe - oxygen deficient TiO composite films: A room temperature, highly carrier polarized magnetic semiconductor
Nano granular metallic iron (Fe) and titanium dioxide (TiO) were
co-deposited on (100) lanthanum aluminate (LaAlO) substrates in a low
oxygen chamber pressure using a pulsed laser ablation deposition (PLD)
technique. The co-deposition of Fe and TiO resulted in 10 nm
metallic Fe spherical grains suspended within a TiO matrix. The
films show ferromagnetic behavior with a saturation magnetization of 3100 Gauss
at room temperature. Our estimate of the saturation magnetization based on the
size and distribution of the Fe spheres agreed well with the measured value.
The film composite structure was characterized as p-type magnetic semiconductor
at 300 K with a carrier density of the order of . The
hole carriers were excited at the interface between the nano granular Fe and
TiO matrix similar to holes excited in the metal/n-type
semiconductor interface commonly observed in Metal-Oxide-Semiconductor (MOS)
devices. From the large anomalous Hall effect directly observed in these films
it follows that the holes at the interface were strongly spin polarized.
Structure and magneto transport properties suggested that these PLD films have
potential nano spintronics applications.Comment: 6 pages in Latex including 8 figure
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