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 $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ 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

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

Morphology of <i>Tnnt2</i>^+/+ (wildtype), <i>Tnnt2</i>^+/⁻, and <i>Tnnt2</i>^−/− embryos.

<p>A. Column 1, representative embryos at age 9.5 days postcoitum. Columns 2–3, whole embryos and hearts stained with H&E at low and high power respectively. Columns 4–6, transmission electron microscopy of hearts at increasing magnifications. Whereas <i>Tnnt2</i>^+/− embryos appeared normal, <i>Tnnt2</i>^−/− embryos showed pericardial effusions on gross inspection, thinning of the myocardium on H&E histology, and loss of organized sarcomeres on electron microscopy. B. A northern blot of total pooled RNA from five embryos of each genotype (<i>Tnnt2</i>^+/+, <i>Tnnt2</i>^−/−, and <i>Tnnt2</i>^+/−) hybridized with a probe complementary to the <i>Tnnt2</i> transcript showed absence of transcript in <i>Tnnt2</i>^−/− embryos and a 29% deficit of transcript in <i>Tnnt2</i>^+/− relative to <i>Tnnt2</i>^+/+ embryos.</p

Characteristics of the force-pCa relationships in skinned papillary muscle fibers.

<p>pCa₅₀, pCa required for generation of 50% of maximal force. <i>n</i>, number of skinned fibers studied, taken from a total of 6 hearts in each group. NS, not significant. Data: mean±SE. <i>p</i> values correspond to the comparison between <i>Tnnt2</i>^+/−/TG^WT and <i>Tnnt2</i>^+/−/TG^K210Δ fibers at the same sarcomere length.</p

Tnnt2 gene expression in mouse lines.

<p>A. Northern blots of total cardiac RNA from wildtype (WT) and <i>Tnnt2</i> heterozygous ablated (<i>Tnnt2</i>^+/−) mice using probes complementary to the coding sequence and the 3′ untranslated region (UTR) of the <i>Tnnt2</i> transcript, and the GAPDH transcript as a loading control. A mild deficit in <i>Tnnt2</i> transcript, quantified at 18% by densitometry, was apparent in <i>Tnnt2</i>^+/− mice. B. Northern blots of total cardiac RNA from mice of the indicated genotypes using a probe complementary to the coding sequence of the <i>Tnnt2</i> transcript, comprising both endogenous and transgene transcript (total); and a probe complementary to the human growth hormone 3′ UTR, specific to the transgene transcript. The intensity of 18S and 28S rRNA bands from ethidium bromide stained agarose gels was used to quantify RNA loading. Significant increases in <i>Tnnt2</i> transcript were apparent in mice carrying the wildtype (TG^WT) or the K210Δ <i>Tnnt2</i> (TG^K210Δ) transgene. C. Reverse transcription-PCR and sequencing of cardiac <i>Tnnt2</i> mRNA showing deletion of codon AAG encoding lysine at position 210 in hearts from TG^K210Δ and <i>Tnnt2</i>^+/−/TG^K210Δ, but not wildtype (WT), mice. D. Immunoblots of total protein extracts from the hearts of wildtype (WT) and <i>Tnnt2</i>^+/− mice using antibodies specific for cardiac troponin T (cTnT), troponin C (TnC), troponin I (cTnI), tropomyosin, actin, and α myosin heavy chain (MHC). GAPDH loading control immunoblots are shown corresponding to the membranes used for the immunoblots above. Levels of these sarcomeric proteins were unchanged between genotypes. E. An immunoblot of total protein extracts from the hearts of three wildtype, <i>Tnnt2</i>^+/−, <i>Tnnt2</i>^+/−/TG^K210Δ, and <i>Tnnt2</i>^+/−/TG^WT mice was performed using an antibody specific for cardiac troponin T (cTnT). cTnT protein levels were unchanged among all genotypes. Electrophoresis of these protein extracts on a polyacrylamide gel, followed by Coomassie blue staining, was used to correct for the relative quantity of protein loaded for the immunoblot.</p