The James Webb Space Telescope Mission: Optical Telescope Element Design, Development, and Performance

The James Webb Space Telescope (JWST) is a large, infrared space telescope that has recently started its science program which will enable breakthroughs in astrophysics and planetary science. Notably, JWST will provide the very first observations of the earliest luminous objects in the Universe and start a new era of exoplanet atmospheric characterization. This transformative science is enabled by a 6.6 m telescope that is passively cooled with a 5-layer sunshield. The primary mirror is comprised of 18 controllable, low areal density hexagonal segments, that were aligned and phased relative to each other in orbit using innovative image-based wavefront sensing and control algorithms. This revolutionary telescope took more than two decades to develop with a widely distributed team across engineering disciplines. We present an overview of the telescope requirements, architecture, development, superb on-orbit performance, and lessons learned. JWST successfully demonstrates a segmented aperture space telescope and establishes a path to building even larger space telescopes.Comment: accepted by PASP for JWST Overview Special Issue; 34 pages, 25 figure

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

The development and validation of a scoring tool to predict the operative duration of elective laparoscopic cholecystectomy

Background: The ability to accurately predict operative duration has the potential to optimise theatre efficiency and utilisation, thus reducing costs and increasing staff and patient satisfaction. With laparoscopic cholecystectomy being one of the most commonly performed procedures worldwide, a tool to predict operative duration could be extremely beneficial to healthcare organisations. Methods: Data collected from the CholeS study on patients undergoing cholecystectomy in UK and Irish hospitals between 04/2014 and 05/2014 were used to study operative duration. A multivariable binary logistic regression model was produced in order to identify significant independent predictors of long (> 90 min) operations. The resulting model was converted to a risk score, which was subsequently validated on second cohort of patients using ROC curves. Results: After exclusions, data were available for 7227 patients in the derivation (CholeS) cohort. The median operative duration was 60 min (interquartile range 45–85), with 17.7% of operations lasting longer than 90 min. Ten factors were found to be significant independent predictors of operative durations > 90 min, including ASA, age, previous surgical admissions, BMI, gallbladder wall thickness and CBD diameter. A risk score was then produced from these factors, and applied to a cohort of 2405 patients from a tertiary centre for external validation. This returned an area under the ROC curve of 0.708 (SE = 0.013, p  90 min increasing more than eightfold from 5.1 to 41.8% in the extremes of the score. Conclusion: The scoring tool produced in this study was found to be significantly predictive of long operative durations on validation in an external cohort. As such, the tool may have the potential to enable organisations to better organise theatre lists and deliver greater efficiencies in care

The Catalan world map of the R. biblioteca estense at modena [cartographic material] : with memoir /

Relief shown pictorially.; Accompanied by text in portfolio (10, [1] p. 36 cm.); Map only, also available online http://nla.gov.au/nla.map-vn1600394

Politically allocated land rights and the geography of electoral violence: the case of Kenya in the 1990s

Large literatures in political theory and political economy argue that private property regimes help support liberal electoral regimes by constraining majoritarian politics, lowering the stakes of elections, and protecting “fundamental” or minority rights. This article probes implications of this argument for elections in sub-Saharan Africa, a mostly rural continent where only about 2% to 10% of all rural property (by country) is held under private title. Do Africa’s rural property regimes shape electoral dynamics and, if so, which ones, and how? This article examines the case of Kenya, focusing on 1991-1992 electoral dynamics in rural zones in which the state itself has exercised direct prerogative over land allocation. We show that in these zones, politicians manipulated land rights to mobilize supporters and punish opponents. They did so in ways that contributed directly to widespread land-related violence at election time. References to other African cases help generalize and set scope conditions on the argument

Incidence and Early Course of Retlnonathy of Prematurity

In the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity (ROP), 4099 infants weighing less than 1251 g at birth underwent sequential ophthalmic examinations, beginning at age 4 to 6 weeks, to monitor the incidence and course of ROP. Overall, 65.8% of the infants developed ROP to some degree; 81.6% for infants of less than 1000 g birth weight. As expected, ROP incidence and severity were higher in lower birth weight and gestational age categories. Black infants appeared less susceptible to ROP, of all severity categories, than nonblack infants. The timing of retinal vascular events correlated more closely with postconceptional age than with postnatal age, implicating the level of maturity more than postnatal environmental influences in governing the timing of these vascular events. These results include the current incidence of various severity stages of ROP found in the United States and provide new. insight into the development of ROP. © 1991, American Academy of Ophthalmology, Inc. All rights reserved