A Low Noise Receiver for Submillimeter Astronomy

A broadband, low noise heterodyne receiver, suitable for astronomical use, has been built using a Pb alloy superconducting tunnel junction (SIS). The RF coupling is quasioptical via a bowtie antenna on a quartz lens and is accomplished without any tuning elements. In its preliminary version the double sideband receiver noise temperature rises from 205 K at 116 GHz to 815 K at 466 GHz. This is the most sensitive broadband receiver yet reported for sub-mm wavelengths. Its multi-octave sensitivity and low local oscillator power requirements make this receiver ideal for remote ground observatories or space-borne telescopes such as NASA's Large Deployable Reflector. A version of this receiver is now being built for NASA's Kuiper Airborne Observatory

A λ = 1.3 Millimeter Aperture Synthesis Molecular Line Survey of Orion Kleinmann-Low

We present a 1".3 spatial resolution interferometric spectral line survey of the core of the Orion molecular cloud, obtained with the OVRO millimeter array. Covering 4 GHz bandwidth in total, the survey contains ~100 emission lines from 18 chemical species. The spatial distributions of a number of molecules point to source I near the IRc2 complex as the dominant energy source in the region but do not rule out the presence of additional lower luminosity objects. At arcsecond resolution, the offsets between dust emission and various molecular tracers suggest that the spectacular "hot core" emission in the Orion core arises via the heating and ablation of material from the surfaces of very high density clumps located ≳500 AU from source I and traced by the dust emission. We find no evidence for a strong internal heating source within the hot core condensation(s)

Constitutional Law

Covers cases on court interpretation of the power to amend initiatives (Olson), on occupational tax—interstate commerce—due process (Woody), and on freedom of the press—prior restraint—procedural due process—equal protection—Washington comic book statute (Bottiger)

Dayem-Martin (SIS tunnel junction) mixers for low noise heterodyne receivers

Superconducting thin film tunnel junctions of small area (.1 → 1 μm^2) have properties which make them suitable for high frequency (≳100 GHz) heterodyne receivers. Both pair and single quasiparticle tunneling is present in these devices, but it is found that the mixing due to the pair effect is apparently excessively noisy, whereas the single quasiparticle effect has a low noise character which gives hope for near quantum limited performance. The physical effect involved is photon assisted quasiparticle tunneling and was first observed by Dayem and Martin[1]. We have made laboratory tests at 115 and 230 GHz which gave single side band (SSB) mixer noise temperatures of 60 and 300 K respectively. Also we have fabricated a 90-140 GHz receiver for the Caltech Owens Valley Radio Observatory which has an overall receiver noise temperature of about 300 K (SSB)

A Low Noise Receiver for Submillimeter Astronomy

A broadband, low noise heterodyne receiver, suitable for astronomical use, has been built using a Pb alloy superconducting tunnel junction (SIS). The RF coupling is quasioptical via a bowtie antenna on a quartz lens and is accomplished without any tuning elements. In its preliminary version the double sideband receiver noise temperature rises from 205 K at 116 GHz to 815 K at 466 GHz. This is the most sensitive broadband receiver yet reported for sub-mm wavelengths. Its multi-octave sensitivity and low local oscillator power requirements make this receiver ideal for remote ground observatories or space-borne telescopes such as NASA's Large Deployable Reflector. A version of this receiver is now being built for NASA's Kuiper Airborne Observatory

The effect of thyroxine on thyroid function

This bulletin is a report on Department of Dairy Husbandry Research Project 80, 'Endocrine Genetics'--P. [2].Digitized 2007 AES.Includes bibliographical references (pages 51-55)

The retention of goitrogens in the blood and tissues of several domestic animals

Publication authorized July 2, 1948Digitized 2007 AES.Includes bibliographical references (pages 33-36)

Progress in a social work writing course: Self-efficacy, course objectives, and skills

Although instructors express concerns about social work students’ writing skills, little research has been conducted. One remedy is a social work-focused writing course. This study assessed a required writing course with a sample of 49 baccalaureate students. From online pre- and post-test surveys, two student outcomes improved significantly: self-reported scores for writing self-efficacy and competence in course objectives. On-demand writing samples improved significantly based on anonymous rating by the course instructors; however, blind ratings found gains but not at a significant level. Improved outcomes were not associated with demographic or background characteristics. We discuss limitations of the study and implications for social work education