Review of the absorption spectra of solid O2 and N2 as they relate to contamination of a cooled infrared telescope

During contamination studies for the liquid helium cooled shuttle infrared telescope facility, a literature search was conducted to determine the absorption spectra of the solid state of homonuclear molecules of O2 and N2, and ascertain what laboratory measurements of the solid have been made in the infrared. With the inclusion of one unpublished spectrum, the absorption spectrum of the solid oxygen molecule has been thoroughly studied from visible to millimeter wavelengths. Only two lines appear in the solid that do not also appear in the gas or liquid. A similar result is implied for the solid nitrogen molecule because it also is homonuclear. The observed infrared absorption lines result from lattice modes of the alpha phase of the solid, and disappear at the warmer temperatures of the beta, gamma, and liquid phases. They are not observed from polycrystalline forms of O2, while strong scattering is. Scattering, rather than absorption, is considered to be the principal natural contamination problem for cooled infrared telescopes in low earth orbit

A simple antireflection overcoat for opaque coatings in the submillimeter region

An antireflection overcoat for opaque baffle coatings in the far infrared (FIR)/submillimeter region was made from a simple Teflon spray-on lubricant. The Teflon overcoat reduced the specular reflectance of four different opaque coatings by nearly a factor of two. Analysis, based on the interference term of a reflecting-layer model, indicates that in the submillimeter region the reduced reflectance depends primarily on the refractive index of the overcoat and very little on its thickness

BRDF measurements of sunshield and baffle materials for the IRAS telescope

Measurements of the far-infrared bidirectional reflectance distribution functions (BRDF) of four samples of Martin Black coating and one sample of gold coated aluminum from the telescope to be flown on the Infrared Astronomy Satellite (IRAS) are presented. At incidence angles near 35 deg Martin Black is a diffuse reflector at wavelengths as long as 36 microns. The gold coated aluminum sample from the IRAS sunshield has a visible grain which causes a strong diffraction enhancement of the BRDF at large nonspecular angles. This enhancement from the sunshield will increase the stray light level inside the telescope

A Reflective Evaluation of Group Assessment

There is a general agreement in the literature that groupwork helps to develop important interpersonal and personal skills (Race, 2001; Visram & Joy, 2003; Elliot & Higgins, 2005; Kench et al, 2008). However, one of the problems with groupwork for both students and lecturers is how the work should be assessed (Parsons & Kassabova, 2002). The possibility of having ‘free-riders’ and the difficulty of fairly awarding marks to reflect the level of students’ contribution to a group output are some of the key problem areas in groupwork assessment (Race, 2001). Peer assessment is seen as one of the methods to deal with these problems. It can generally involve students assessing each other’s level of contribution to the group’s output (Visram & Joy, 2003). This paper provides our reflection on the use of peer assessment on a student group project

Does welfare reform affect fertility? Evidence from the UK

In 1999 the UK government made major reforms to the system of child-contingent benefits, including the introduction of Working Families’ Tax Credit and an increase in means-tested Income Support for families with children. Between 1999-2003 government spending per-child on these benefits rose by 50 per cent in real terms, a change that was unprecedented over a thirty year period. This paper examines whether there was a response in childbearing. To identify the effect of the reforms, we exploit the fact that the spending increases were targeted at low-income households and we use the (exogenously determined) education of the woman and her partner to define treatment and control groups. We argue that the reforms are most likely to have a positive fertility effect for women in couples and show that this is the case. We find that there was an increase in births (by around 15 per cent) among the group affected by the reforms

Stable oxygen and carbon isotope compositional fields for skeletal and diagenetic components in New Zealand Cenozoic nontropical carbonate sediments and limestones: a synthesis and review

The stable oxygen isotope composition (d¹⁸O) of a precipitated carbonate depends mainly on the isotope composition, salinity, and temperature of the host fluid, whereas the stable carbon isotope composition (d¹³C) reflects the source of CO2 for precipitation, such as meteoric or sea water, shell dissolution, or various biochemical origins, including microbial oxidation of organic matter and methane. Despite the potentially complex array of controls, natural waters tend to show a characteristic range of isotope values which in turn are mimicked or tracked by the carbonate minerals precipitated from them. Consequently, plots of d¹⁸O versus d¹³C for carbonate materials can help identify their depositional and/or diagenetic environment(s)

Implementing Transitive Credit with JSON-LD

Science and engineering research increasingly relies on activities that facilitate research but are not currently rewarded or recognized, such as: data sharing; developing common data resources, software and methodologies; and annotating data and publications. To promote and advance these activities, we must develop mechanisms for assigning credit, facilitate the appropriate attribution of research outcomes, devise incentives for activities that facilitate research, and allocate funds to maximize return on investment. In this article, we focus on addressing the issue of assigning credit for both direct and indirect contributions, specifically by using JSON-LD to implement a prototype transitive credit system.Comment: accepted by WSSSPE2 - http://wssspe.researchcomputing.org.uk/wssspe2

Effect of velocity overshoot on the performance of magnetohydrodynamic subsonic diffusers

The evolution of an overshoot velocity distribution was studied in a plane two dimensional diffuser as a function of diffuser divergence angle. The diffuser performance for velocity overshoot was compared to that for a fully developed inlet velocity profile. Results indicate that the ratio of peak-to-center line velocity increases along the diffuser for a diffuser half angle greater than some critical value. It was also found that irrespective of the accompanying inlet temperature distribution, the wall shear stress and the wall heat flux is substantially larger when the inlet velocity profile has an overshoot than that for a fully developed inlet velocity profile

Interpretive computer simulator for the NASA Standard Spacecraft Computer-2 (NSSC-2)

An Interpretive Computer Simulator (ICS) for the NASA Standard Spacecraft Computer-II (NSSC-II) was developed as a code verification and testing tool for the Annular Suspension and Pointing System (ASPS) project. The simulator is written in the higher level language PASCAL and implented on the CDC CYBER series computer system. It is supported by a metal assembler, a linkage loader for the NSSC-II, and a utility library to meet the application requirements. The architectural design of the NSSC-II is that of an IBM System/360 (S/360) and supports all but four instructions of the S/360 standard instruction set. The structural design of the ICS is described with emphasis on the design differences between it and the NSSC-II hardware. The program flow is diagrammed, with the function of each procedure being defined; the instruction implementation is discussed in broad terms; and the instruction timings used in the ICS are listed. An example of the steps required to process an assembly level language program on the ICS is included. The example illustrates the control cards necessary to assemble, load, and execute assembly language code; the sample program to to be executed; the executable load module produced by the loader; and the resulting output produced by the ICS