Commentary: JWST near-infrared detector degradation— finding the problem, fixing the problem, and moving forward

The James Webb Space Telescope (JWST) is the successor to the Hubble Space Telescope. JWST will be an infrared-optimized telescope, with an approximately 6.5 m diameter primary mirror, that is located at the Sun-Earth L2 Lagrange point. Three of JWST’s four science instruments use Teledyne HgCdTe HAWAII-2RG (H2RG) near infrared detector arrays. During 2010, the JWST Project noticed that a few of its 5 μm cutoff H2RG detectors were degrading during room temperature storage, and NASA chartered a “Detector Degradation Failure Review Board” (DD-FRB) to investigate. The DD-FRB determined that the root cause was a design flaw that allowed indium to interdiffuse with the gold contacts and migrate into the HgCdTe detector layer. Fortunately, Teledyne already had an improved design that eliminated this degradation mechanism. During early 2012, the improved H2RG design was qualified for flight and JWST began making additional H2RGs. In this article, we present the two public DD-FRB “Executive Summaries” that: (1) determined the root cause of the detector degradation and (2) defined tests to determine whether the existing detectors are qualified for flight. We supplement these with a brief introduction to H2RG detector arrays, some recent measurements showing that the performance of the improved design meets JWST requirements, and a discussion of how the JWST Project is using cryogenic storage to retard the degradation rate of the existing flight spare H2RGs

Probing the sheath electric field with a crystal lattice by using thermophoresis in dusty plasma

A two-dimensional dust crystal levitated in the sheath of a modified Gaseous Electronics Conference (GEC) reference cell is manipulated by heating or cooling the lower electrode. The dust charge is obtained by measuring global characteristics of the levitated crystal obtained from top-view pictures. From the force balance, the electric field in the sheath is reconstructed. From the Bohm criterion, we conclude that the dust crystal is levitated mainly above and just below the classical Bohm point

European Springtails Orchesella cincta (L.) and O. villosa (L.) (Collembola: Entomobryidae): Vagabond Species of the Nearctic Region

North American specimens of the European invasive springtail Orchesella cincta (L.) were compared to several published European haplotypes in a phylogenetic framework using likelihood methods based on a portion of cytochrome oxidase II (cox2). Our analyses provide direct evidence of at least two distinct introductions of this invasive to North America from different regions of Europe. Additional introduction events cannot be ruled out because detection is limited by extremely low sequence divergence among populations inhabiting different regions of the continent. Orchesella villosa (L.), another invasive from Europe, is another candidate for multiple introductions. Herein we include the cox2 sequence from single specimens of O. villosa from Maine and Oregon. Although these two specimens are identical in sequence, they differ from a published sequence from a European specimen by 15%, indicating significant undocumented genetic variation in the natal range of O. villosa. Additional sampling of Nearctic populations of O. villosa might reveal the same situation reported herein for O. cincta

The Sense and Sensibility of Qualitative Research

David Silverman\u27s new edition of Qualitative Research addresses how to engage in qualitative research with increased sensibility. The book is divided into seven sections with 23 chapters written by premier researchers. The chapters are written for students rather than the writers\u27 peers, and while every chapter makes extensive use of the authors\u27 fieldwork and data, John Heritage\u27s chapter on conversational analysis (CA) stands out because he demonstrates to the reader how he made sense of a recurring piece of talk he calls an oh-prefaced response. The papers are clearly written with helpful summaries and suggested further readings and online resources. Less helpful are the questions posed at the end of each chapter

Lived Religion: An Examination of Pass the Salt Luncheons.

This study used a case study approach to examine how religious culture, such as theologies and doctrines, is lived or practiced by Pass the Salt luncheon participants. Pass the Salt participants are taught the teachings of Harvest Evangelism, an interdenominational Para-church organization; these teachings are evidenced through their cultural toolkit. It was expected that the luncheon participants would practice Harvest Evangelism\u27s religious culture in the workplace. Participant observation and personal interviews were conducted to examine participants\u27 application of the cultural toolkit to their everyday lives, specifically in the workplace. Findings indicated that the leader of the Pass the Salt luncheon was more likely to practice or live the religious doctrines provided by Harvest Evangelism, while others lived religion in a different way

The Sunshine of My Dear Old Home In Maine

https://digitalcommons.library.umaine.edu/mmb-me/1255/thumbnail.jp