3,451 research outputs found
Etching of aluminum for bonding Patent
Etching aluminum alloys with aqueous solution containing sulfuric acid, hydrofluoric acid, and an alkali metal dischromate for adhesive bondin
Influence of aerosols, clouds, and sunglint on polarization spectra of Earthshine
Ground-based observations of the Earthshine, i.e., the light scattered by
Earth to the Moon, and then reflected back to Earth, simulate space
observations of our planet and represent a powerful benchmark for the studies
of Earth-like planets. Earthshine spectra are strongly linearly polarized,
owing to scattering by molecules and small particles in the atmosphere of the
Earth and surface reflection, and may allow us to measure global atmospheric
and surface properties of planet Earth. Aims. We aim to interpret already
published spectropolarimetric observations of the Earthshine by comparing them
with new radiative transfer model simulations including a fully realistic
three-dimensional (3D) surface-atmosphere model for planet Earth. We used the
highly advanced Monte Carlo radiative transfer model MYSTIC to simulate
polarized radiative transfer in the atmosphere of the Earth without
approximations regarding the geometry, taking into account the polarization
from surface reflection and multiple scattering by molecules, aerosol
particles, cloud droplets, and ice crystals. We have shown that Earth
spectropolarimetry is highly sensitive to all these input parameters, and we
have presented simulations of a fully realistic Earth atmosphere-surface model
including 3D cloud fields and two-dimensional (2D) surface property maps. Our
modeling results show that scattering in high ice water clouds and reflection
from the ocean surface are crucial to explain the continuum polarization at
longer wavelengths as has been reported in Earthshine observations taken at the
Very Large Telescope in 2011 (3.8 % and 6.6 % at 800 nm, depending on which
part of Earth was visible from the Moon at the time of the observations). We
found that the relatively high degree of polarization of 6.6 % can be
attributed to light reflected by the ocean surface in the sunglint region
Shifts in Federal Educational Policies and The Effect on Middle Tennessee Band Programs
The objectives of this thesis are to examine how federal legislation for education has impacted music education and to identify trends that may shape the future funding and operation of band programs in Middle Tennessee
Spectral and Temporal Variability of Earth Observed in Polarization
We present a comprehensive set of spectropolarimetric observations of
Earthshine as obtained by FORS2 at the VLT for phase angles from 50degree to
135degree (Sun-Earth-Moon angle), covering a spectral range from 430nm to
920nm. The degree of polarization in BVRI passbands, the differential
polarization vegetation index, and the equivalent width of the O2A polarization
band around 760nm are determined with absolute errors around 0.1 percent in the
degree of polarization. Earthshine polarization spectra are corrected for the
effect of depolarization introduced by backscattering on the lunar surface,
introducing systematic errors of the order of 1 percent in the degree of
polarization. Distinct viewing sceneries such as observing the Atlantic or
Pacific side in Earthshine yield statistically different phase curves. The
equivalent width defined for the O2A band polarization is found to vary from
-5nm to +2nm. A differential polarized vegetation index is introduced and
reveals a larger vegetation signal for those viewing sceneries that contain
larger fractions of vegetated surface areas. We corroborate the observed
correlations with theoretical models from the literature, and conclude that the
Vegetation Red Edge(VRE) is a robust and sensitive signature in polarization
spectra of planet Earth. The overall behaviour of polarization of planet Earth
in the continuum and in the O2A band can be explained by existing models.
Biosignatures such as the O2A band and the VRE are detectable in Earthshine
polarization with a high degree of significance and sensitivity. An in-depth
understanding of Earthshines temporal and spectral variability requires
improved models of Earths biosphere, as a prerequisite to interpret possible
detections of polarised biosignatures in earthlike exoplanets in the future.Comment: 19 pages, 14 figures, 3 table
Parents\u27 Perceptions of and Experiences with School Counselors
Research has found that parents may feel isolated from their children\u27s schools due to their own problematic educational experiences or their lack of understanding their children\u27s school experiences. Current literature explores stakeholders\u27 perceptions of school counselors but lacks specific context from a parental perspective. Validating parents\u27 perceptions of and experiences with school counselors enhances students\u27 academic success by providing insight about what motivates parents to invest in their children\u27s schools and how school counselors influence parental involvement. Utilizing key concepts related to the importance of parental involvement for student success, this qualitative study focused on the experiences and perceptions of parents regarding their children\u27s high school counselors. Criterion and snowball sampling was used to recruit 8 parents from 5 different high schools across the Midwestern United States. Interview data were analyzed through clustering and horizontalization processes, revealing 4 specific themes: student benefits, in which school counselors directly supported students; parents feeling empowered, in which school counselors validated concerns and empowered parents; school counselor providing interpersonal environment, where students believed school counselors cared about them as individuals and strove for their success; and informed school counselor, where school counselors capitalized on their expertise and professional experience for the direct benefit of students. These emerging themes strengthen existing research and provide current and future school counselors with insight into building and maintaining collaborative relationships with parents, including advocacy efforts to increase student success
Inapproximability of the Standard Pebble Game and Hard to Pebble Graphs
Pebble games are single-player games on DAGs involving placing and moving
pebbles on nodes of the graph according to a certain set of rules. The goal is
to pebble a set of target nodes using a minimum number of pebbles. In this
paper, we present a possibly simpler proof of the result in [CLNV15] and
strengthen the result to show that it is PSPACE-hard to determine the minimum
number of pebbles to an additive term for all , which improves upon the currently known additive constant hardness of
approximation [CLNV15] in the standard pebble game. We also introduce a family
of explicit, constant indegree graphs with nodes where there exists a graph
in the family such that using constant pebbles requires moves
to pebble in both the standard and black-white pebble games. This independently
answers an open question summarized in [Nor15] of whether a family of DAGs
exists that meets the upper bound of moves using constant pebbles
with a different construction than that presented in [AdRNV17].Comment: Preliminary version in WADS 201
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