32 research outputs found
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
Adding parallelism capabilities to ACL2
We have implemented parallelism primitives that permit an ACL2 programmer to parallelize execution of ACL2 functions. We (1) introduce logical definitions for these primitives, (2) explain the features of our extension, (3) give an evaluation strategy for our implementation, and (4) use the parallelism primitives in examples to show speedup. Categories and Subject Descriptors D.1 [Programming Techniques]: Concurrent Programming—parallel programming; D.2.4 [Software Engineering]: Software/Program Verification—correctness proofs, formal methods; D.3.2 [Programming Languages]: Language Classifications—applicative (functional) language
Positive and Negative Tone Water Processable Photoresists: A Progress Report
This paper presents the progress we have made toward the development of fully water processable, negative and positive tone I-line resist systems. The negative tone system is based on styrene copolymers bearing pendant ammonium sulfonate groups and vicinal diol functionalities. The salt provides the means of rendering the polymer water soluble. The diol undergoes an acid catalyzed pinacol rearrangement that results in a polarity switch within the exposed polymer film, i.e. a solubility differential. The styrene backbone was chosen to provide dry etch resistance. Positive tone imaging requires two solubility switches. The two solubility switches are based on the reaction between acidic hydroxyl groups in a matrix polymer and vinyl ethers that are introduced as a pendant group of the polymer or as a monomeric cross-linker, i.e. a bisvinyl ether. During the post application bake, the vinyl ether reacts with an acidic hydroxyl group in a thermally activated switch, forming a crosslinked, water insoluble network through acetal linkages. These acid labile crosslink sites are then cleaved by a photochemical switch through the generation of acid, thereby rendering the exposed areas water developable