226 research outputs found
The Automated Array Assembly Task of the Low-cost Silicon Solar Array Project, Phase 2
An advanced process sequence for manufacturing high efficiency solar cells and modules in a cost-effective manner is discussed. Emphasis is on process simplicity and minimizing consumed materials. The process sequence incorporates texture etching, plasma processes for damage removal and patterning, ion implantation, low pressure silicon nitride deposition, and plated metal. A reliable module design is presented. Specific process step developments are given. A detailed cost analysis was performed to indicate future areas of fruitful cost reduction effort. Recommendations for advanced investigations are included
Processing experiments on non-Czochralski silicon sheet
A program is described which supports and promotes the development of processing techniques which may be successfully and cost-effectively applied to low-cost sheets for solar cell fabrication. Results are reported in the areas of process technology, cell design, cell metallization, and production cost simulation
An Absence of Gaps in the Main Sequence Population of Field Stars
Using high precision parallaxes from the Hipparcos catalog, we construct H-R
diagrams for two samples of bright stars. The first is a magnitude-limited
sample that is over 90% complete and uses uniform photometry from the Catalog
of WBVR Magnitudes of Northern Sky Bright Stars (declination above -14 deg).
This sample shows a smooth distribution of stars along the main sequence, with
no detectable gaps. The second contains all of the stars closer than 100
parsecs in the Hipparcos catalog with declination less than -12 deg. Uniform
spectroscopy from the Michigan Spectral Survey shows that some stars which
appear on the main sequence in the H-R diagram, particularly those in the 0.2 <
B-V < 0.3 region that has been labeled the Bohm-Vitense gap, are classified as
giants by the MK system of spectral classification. Other gaps that have been
identified in the main sequence are also affected by such classification
criteria. This analysis casts doubt on the existence of the Bohm-Vitense gap,
which is thought to result from the sudden onset of convection in stars. The
standard identification of main sequence stars with luminosity class V, and
giants with luminosity class III, must be reconsidered for some spectral types.
The true nature of the stars that lie on the main sequence in the H-R diagram,
but which do not have luminosity class V designations, remains to be
investigated.Comment: 8 pages, 4 figures, Ap J Lett (accepted
Bioinformatics advances in saliva diagnostics
There is a need recognized by the National Institute of Dental & Craniofacial Research and the National Cancer Institute to advance
basic, translational and clinical saliva research. The goal of the Salivaomics Knowledge Base (SKB) is to create a data management system and web resource constructed to support human salivaomics research. To maximize the utility of the SKB for retrieval,
integration and analysis of data, we have developed the Saliva Ontology and SDxMart. This article reviews the informatics advances in saliva diagnostics made possible by the Saliva Ontology and SDxMart
Local and global behaviour of nonlinear equations with natural growth terms
This paper concerns a study of the pointwise behaviour of positive solutions
to certain quasi-linear elliptic equations with natural growth terms, under
minimal regularity assumptions on the underlying coefficients. Our primary
results consist of optimal pointwise estimates for positive solutions of such
equations in terms of two local Wolff's potentials.Comment: In memory of Professor Nigel Kalto
Detailed Analysis of Nearby Bulgelike Dwarf Stars III. Alpha and Heavy-element abundances
The present sample of nearby bulgelike dwarf stars has kinematics and
metallicities characteristic of a probable inner disk or bulge origin. Ages
derived by using isochrones give 10-11 Gyr for these stars and metallicities
are in the range -0.80< [Fe/H]< +0.40. We calculate stellar parameters from
spectroscopic data, and chemical abundances of Mg, Si, Ca, Ti, La, Ba, Y, Zr
and Eu are derived by using spectrum synthesis.
We found that [alpha-elements/Fe] show different patterns depending on the
element. Si, Ca and Ti-to-iron ratios decline smoothly for increasing
metallicities, and follow essentially the disk pattern. O and Mg, products of
massive supernovae, and also the r-process element Eu, are overabundant
relative to disk stars, showing a steeper decline for metallicities [Fe/H] >
-0.3 dex. [s-elements/Fe] roughly track the solar values with no apparent trend
with metallicity for [Fe/H] < 0, showing subsolar values for the metal rich
stars. Both kinematical and chemical properties of the bulgelike stars indicate
a distinct identity of this population when compared to disk stars.Comment: 21 pages, 9 figures, to appear in Ap
Generalized Swiss-cheese cosmologies: Mass scales
We generalize the Swiss-cheese cosmologies so as to include nonzero linear
momenta of the associated boundary surfaces. The evolution of mass scales in
these generalized cosmologies is studied for a variety of models for the
background without having to specify any details within the local
inhomogeneities. We find that the final effective gravitational mass and size
of the evolving inhomogeneities depends on their linear momenta but these
properties are essentially unaffected by the details of the background model.Comment: 10 pages, 14 figures, 1 table, revtex4, Published form (with minor
corrections
Generalized Swiss-Cheese Cosmologies II: Spherical Dust
The generalized Swiss - cheese model, consisting of a Lema\^itre - Tolman
(inhomogeneous dust) region matched, by way of a comoving boundary surface,
onto a Robertson-Walker background of homogeneous dust, has become a standard
construction in modern cosmology. Here we ask if this construction can be made
more realistic by introducing some evolution of the boundary surface. The
answer we find is no. To maintain a boundary surface using the Darmois - Israel
junction conditions, as opposed to the introduction of a surface layer, the
boundary must remain exactly comoving. The options are to drop the assumption
of dust or allow the development of surface layers. Either option fundamentally
changes the original construction.Comment: 5 pages revtex 4.1 Final form to appear in Phys. Rev.
Analytic Metaphysics versus Naturalized Metaphysics: The Relevance of Applied Ontology
The relevance of analytic metaphysics has come under criticism: Ladyman & Ross, for instance, have suggested do discontinue the field. French & McKenzie have argued in defense of analytic metaphysics that it develops tools that could turn out to be useful for philosophy of physics. In this article, we show first that this heuristic defense of metaphysics can be extended to the scientific field of applied ontology, which uses constructs from analytic metaphysics. Second, we elaborate on a parallel by French & McKenzie between mathematics and metaphysics to show that the whole field of analytic metaphysics, being useful not only for philosophy but also for science, should continue to exist as a largely autonomous field
DNA resection in eukaryotes: deciding how to fix the break
DNA double-strand breaks are repaired by different mechanisms, including homologous
recombination and nonhomologous end-joining. DNA-end resection, the first step in
recombination, is a key step that contributes to the choice of DSB repair. Resection, an
evolutionarily conserved process that generates single-stranded DNA, is linked to checkpoint
activation and is critical for survival. Failure to regulate and execute this process results in
defective recombination and can contribute to human disease. Here, I review recent findings on
the mechanisms of resection in eukaryotes, from yeast to vertebrates, provide insights into the
regulatory strategies that control it, and highlight the consequences of both its impairment and its
deregulation
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