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

Targeting Social Connection in the Context of Trauma: Functional Outcomes and Mechanisms of Change

The current study presents and preliminarily tests a brief, theory driven intervention designed to target social connectivity as a transdiagnostic mechanism of health. We tested four hypotheses to examine whether and how explicitly targeting social behavior engagement (activating values-led behaviors towards specific network members) may improve other downstream aspects of social connectivity (i.e., social cognitions measured as loneliness, interpersonal closeness, perceived social support) and functioning (quality of life [QOL] and posttraumatic stress symptoms [PTS]). Methods. Participants included 15 patients (10 veterans, 5 firefighters) who completed the six-session intervention. Demographics: age (M = 46, SD = 17), 87% male, race (80% Caucasian, 20% Hispanic), 60% married/partnered, 47% living alone. Our multi-analytic approach included parametric and non-parametric tests: (a) significance testing and effect sizes to examine whether variables of interest changed, and (b) Granger causality analysis of repeated measures to examine the mechanistic theory of change (does social behavior engagement lead to improved social cognition and functioning?). Results. Statistically significant, medium-large effect size improvements were shown for QOL (Cohens d = 1.05), PTS (d = 1.05), social behavior engagement (d = 0.78), and several social cognitions (loneliness, d = 0.80, interpersonal closeness, d = 0.53). Models accounted for medium-large variance explained in improved QOL (R2 = 0.47, 95% CI [0.00,0.66]) and PTS (R2 = 0.56, 95% CI[0.07,0.72]). The theory of change was supported, with increase in social behaviors preceding improvement in social cognitions (not vice-versa). Conclusions. Improving social connectivity is a mechanism for improving QOL and mental health. Focus on initiating values-driven social behaviors may be an efficient and effective entry point to stimulate change

Vector and Axial Form Factors Applied to Neutrino Quasielastic Scattering

We calculate the quasielastic cross sections for neutrino scattering on nucleons using up to date fits to the nucleon elastic electromagnetic form factors GEp, GEn, GMp, GMn, and weak form factors. We show the extraction of Fa for neutrino experiments. We show how well \minerva, a new approved experiment at FNAL, can measure Fa. We show the that Fa has a different contribution to the anti-neutrino cross section, and how the anti-neutrino data can be used to check Fa extracted from neutrino scattering.Comment: Presented by Howard Budd at NuInt04, Mar. 2004, Laboratori Nazionali del Gran Sasso - INFN - Assergi, Ital

Turbulence Driving by Interstellar Pickup Ions in the Outer Solar Wind

We revisit the question of how the unstable scattering of interstellar pickup ions (PUIs) may drive turbulence in the outer solar wind, and why the energy released into fluctuations by this scattering appears to be significantly less than the standard bispherical prediction. We suggest that energization of the newly picked-up ions by the ambient turbulence during the scattering process can result in a more spherical distribution of PUIs, and reduce the generated fluctuation energy to a level consistent with the observations of turbulent intensities and core solar wind heating. This scenario implies the operation of a self-regulation mechanism that maintains the observed conditions of turbulence and heating in the PUI-dominated solar wind.Comment: To be published in The Astrophysical Journa

Black hole head-on collisions and gravitational waves with fixed mesh-refinement and dynamic singularity excision

We present long-term-stable and convergent evolutions of head-on black hole collisions and extraction of gravitational waves generated during the merger and subsequent ring-down. The new ingredients in this work are the use of fixed mesh-refinement and dynamical singularity excision techniques. We are able to carry out head-on collisions with large initial separations and demonstrate that our excision infrastructure is capable of accommodating the motion of the individual black holes across the computational domain as well as their their merger. We extract gravitational waves from these simulations using the Zerilli-Moncrief formalism and find the ring-down radiation to be, as expected, dominated by the l=2, m=0 quasi-normal mode. The total radiated energy is about 0.1 % of the total ADM mass of the system.Comment: Revised version, 1 figure added, accepted for publication in Phys.Rev.D, 15 pages, 10 figures, revtex 4.

Use of the Physician Orders for Life-Sustaining Treatment Program for Patients Being Discharged from the Hospital to the Nursing Facility

Background: The Physician Orders for Life-Sustaining Treatment (POLST) documents patient preferences as medical orders that transfer across settings with patients., Objectives: The objectives were to pilot test methods and gather preliminary data about POLST including (1) use at time of hospital discharge, (2) transfers across settings, and (3) consistency with prior decisions., Study Design: Descriptive with chart abstraction and interviews., Participants: Participants were hospitalized patients discharged to a nursing facility and/or their surrogates in La Crosse County, Wisconsin., Measurements: POLST forms were abstracted from hospital records for 151 patients. Hospital and nursing facility chart data were abstracted and interviews were conducted with an additional 39 patients/surrogates., Results: Overall, 176 patients had valid POLST forms at the time of discharge from the hospital, and many (38.6%; 68/176) only documented code status. When the whole POLST was completed, orders were more often marked as based on a discussion with the patient and/or surrogate than when the form was used just for code status (95.1% versus 13.8%, p<.001). In the follow-up and interview sample, a majority (90.6%; 29/32) of POLST forms written in the hospital were unchanged up to three weeks after nursing facility admission. Most (71.9%; 23/32) appeared consistent with patient or surrogate recall of prior treatment decisions., Conclusion: POLST forms generated in the hospital do transfer with patients across settings, but are often used only to document code status. POLST orders appeared largely consistent with prior treatment decisions. Further research is needed to assess the quality of POLST decisions

Dynamical system representation of open address hash functions

This paper demonstrates how a broad collection of hash function families can be expressed as dynamical systems. We then show that this representation can be useful for analysis. In particular, we provide an analysis which proves that a widely-used family of double hash functions will transform any initial distribution of keys into the uniform distribution over the table space

Polarization of Tau Leptons Produced in Quasielastic Neutrino--Nucleon Scattering

A numerical analysis of the polarization vector of tau leptons produced through quasielastic neutrino and antineutrino interactions with free nucleons is given with two models for vector electromagnetic form factors of proton and neutron. The impact of G parity violating axial and vector second-class currents is investigated by applying a simple heuristic model for the induced scalar and tensor form factors.Comment: Thesis of a talk given at the 8th Scientific Conference (SCYSS-04), Dubna, Russia, 2 - 6 Feb 2004. 11 pages, 6 figures; added references, figures and discussion; conclusions unchange

Experimental and computational characterization of a modified GEC cell for dusty plasma experiments

A self-consistent fluid model developed for simulations of micro- gravity dusty plasma experiments has for the first time been used to model asymmetric dusty plasma experiments in a modified GEC reference cell with gravity. The numerical results are directly compared with experimental data and the experimentally determined dependence of global discharge parameters on the applied driving potential and neutral gas pressure is found to be well matched by the model. The local profiles important for dust particle transport are studied and compared with experimentally determined profiles. The radial forces in the midplane are presented for the different discharge settings. The differences between the results obtained in the modified GEC cell and the results first reported for the original GEC reference cell are pointed out

A Spitzer/IRS spectral study of a sample of galactic carbon-rich proto-planetary nebulae

Recent infrared spectroscopic observations have shown that proto-planetary nebulae (PPNs) are sites of active synthesis of organic compounds in the late stages of stellar evolution. This paper presents a study of Spitzer/IRS spectra for a sample of carbon-rich PPNs, all except one of which show the unidentified 21 micron emission feature. The strengths of the aromatic infrared band (AIB), 21 micron, and 30 micron features are obtained by decomposition of the spectra. The observed variations in the strengths and peak wavelengths of the features support the model that the newly synthesized organic compounds gradually change from aliphatic to aromatic characteristics as stars evolve from PPNs to planetary nebulae.Comment: 32 pages, 11 figures, accepted for publication in Ap