The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

Damped trend exponential smoothing: A modelling viewpoint

Over the past twenty years, damped trend exponential smoothing has performed well in numerous empirical studies, and it is now well established as an accurate forecasting method. The original motivation for this method was intuitively appealing, but said very little about why or when it provided an optimal approach. The aim of this paper is to provide a theoretical rationale for the damped trend method based on Brown's original thinking about the form of underlying models for exponential smoothing. We develop a random coefficient state space model for which damped trend smoothing provides an optimal approach, and within which the damping parameter can be interpreted directly as a measure of the persistence of the linear trend.Time series Exponential smoothing ARIMA models State space models

The Bro1-related protein HD-PTP/PTPN23 is required for endosomal cargo sorting and multivesicular body morphogenesis

The Saccharomyces cerevisiae protein Bro1p is required for sorting endocytic cargo to the lumen of multivesicular bodies (MVBs). The mammalian ortholog of Bro1p is not known; although Alix, a structurally related protein, supports the topologically similar process of virus budding, functional studies have so far failed to identify a role for Alix in MVB formation. To establish whether Alix or similar protein(s) participate in endosomal sorting, we attached a retroviral peptide that binds Alix to a reporter receptor. This chimera was sorted efficiently away from the early endosome to the lumen of late endocytic compartments. Surprisingly, sorting was not prevented by depleting Alix but instead required the Alix-related protein His domain phosphotyrosine phosphatase (HD-PTP)/His-Domain/Type N23 protein tyrosine phosphatase (PTPN23). Depletion of HD-PTP also reduced transfer of fluid-phase markers and EGF receptor to lysosomes, caused the accumulation of ubiquitinated proteins on endosomal compartments and disrupted the morphogenesis of MVBs. Rescue experiments using an RNAi-resistant version of HD-PTP and HD-PTP mutants demonstrated an essential role for the HD-PTP Bro1 domain, with ESCRT-III binding correlating with full biological activity

Role of heparan sulfate in dextral heart looping in chick

Heparan sulfate (HS) has been shown to be involved in left±right asymmetry formation, including the process of dex-tral heart looping during embryonic development. The struc-tural features of HS required in this process, however, have not been explored. In this study, we examined the structure of HS from the heart-forming regions (or heart fields) of Hamburger and Hamilton stage 5±9 chick embryos. No sig-nificant differences were found in HS to chondroitin sulfate (CS) ratio, HS chain length, or [35S] sulfate incorporation at HS disaccharide level between the left and the right heart fields. Compared to other parts of the embryo, however, lower ratio of HS to CS, shorter HS chain length, and higher [35S] sulfate incorporation at 6-O position of the glucosamine residue in the HS chains were observed in the heart-forming regions. Moreover, HS from the left and the right heart fields exhibit differential cleavage by heparanase, an endo-b-D-glucuronidase that cleaves specific sequences within the HS chain. In embryo culture, microinjection of the active human heparanase enzyme into the right but not the left pericardial cavity at stage 7–8 resulted in reversed heart looping in a dose-dependent manner. Heart reversal following microinjec-tion of heparin or heparin derivatives suggests the involvement of N- and 6-O-sulfation but not 2-O-sulfation in the heart looping process. Key words: 6-O-sulfation/chick/heart looping/heparan sulfate/heparanas