Millimeter-wave radiometry for radio astronomy Final report, Nov. 1965 - 31 Dec. 1967

Noise, gain, and antenna data for millimeter wave radiometers, and lunar eclipse observation

Millimeter-wave radiometry for radio astronomy Final report

Lunation study using millimeter wave radiometry for radio astronom

Seeding of high temperature air flow

Seeding of high temperature air flows is problematic because common seeding materials can ignite and may pose a threat for human health in case of inhalation. Sodium chloride is proposed as a seeding material to avoid these problems. The generation of crystals using an ultrasonic atomizer is described and the measured particle size distribution is presented. The described method has the additional advantage that the particle size can easily be adjusted. This allows the operator to comply with the experimental requirements in terms of resolvable frequencies. The described method has been successfully applied to LDA measurements in a 500°C air flo

V-band Bull's eye antenna for multiple discretely steerable beams

We present a new approach to designing V-band Bull’s eye antenna so as to produce multiple beams, which are either fixed or discretely steerable. Bull’s eye antennas comprise concentric rings around a subwavelength aperture. Beam deflection is accomplished by adjusting the effective spacing of the rings, which we explain in terms of the coupling angle to free space and surface waves. We show that multiple beams can be obtained from a single antenna, with the deflection of each beam being controlled independently by the relevant portion of the ring pattern. We demonstrate the principle through rigorous full-wave simulations of two-beam antennas with symmetrical and asymmetrical shifts, and give experimental results for a prototype milled in aluminium, with two separate fixed beams each deflected 16° to either side of the broadside. We also propose means to obtain up to six different beam arrangements during operation by mechanically rotating a plate containing a special six-sector ring pattern. Our simulated example gives three patterns, a single broadside beam or two beams each deflected by 8° or 15°. The radiation efficiency of the antenna is 97%, and the gain of a single undeflected beam is 18.1dBi

A comparison of radome- and astrodome-enclosed large radio telescopes at millimeter wavelengths: The Large Millimeter Telescope

We present a systematic comparison of the main figures of merit for an open-air radio telescope and two different types of enclosed antennas: (1) an ordinary radome, with a metal space frame providing the required mechanical rigidity and a dielectric membrane, and (2) an “astrodome,” i.e., a corotating rigid dome with a large window covered by a tensile membrane structure. The analysis is limited to submillimeter and millimeter wavelengths and large (≳30 m) antenna/enclosure systems, where the window tensile structure is very unlikely to be removable and is supported by either a metal space frame or cable networks. As compared with previous studies of this type, here we concentrate on the specific effects that these large metallic support structures have on sensitive astronomical observations. In particular, we critically discuss how the wind-induced random motions of the metal space frame can limit the sensitivity of continuum observations, as a result of fluctuating shadowing and spillover effects combined with various beam-chopping techniques. Using the Large Millimeter Telescope as a benchmark, we provide baselines for future projects where a similar comparison is needed

Effectiveness of ready-to-use therapeutic food compared to a corn/soy-blend-based pre-mix for the treatment of childhood moderate acute malnutrition in Niger.

Standard nutritional treatment of moderate acute malnutrition (MAM) relies on fortified blended flours though their importance to treat this condition is a matter of discussion. With the newly introduced World Health Organization growth standards, more children at an early stage of malnutrition will be treated following the dietary protocols as for severe acute malnutrition, including ready-to-use therapeutic food (RUTF). We compared the effectiveness of RUTF and a corn/soy-blend (CSB)-based pre-mix for the treatment of MAM in the supplementary feeding programmes (SFPs) supported by Médecins Sans Frontières, located in the Zinder region (south of Niger). Children measuring 65 to <110 cm, newly admitted with MAM [weight-for-height (WHM%) between 70% and <80% of the NCHS median] were randomly allocated to receive either RUTF (Plumpy'Nut®, 1000 kcal day(-1)) or a CSB pre-mix (1231 kcal day(-1)). Other interventions were similar in both groups (e.g. weekly family ration and ration at discharge). Children were followed weekly up to recovery (WHM% ≥ 85% for 2 consecutive weeks). In total, 215 children were recruited in the RUTF group and 236 children in the CSB pre-mix group with an overall recovery rate of 79.1 and 64.4%, respectively (p < 0.001). There was no evidence for a difference between death, defaulter and non-responder rates. More transfers to the inpatient Therapeutic Feeding Centre (I-TFC) were observed in the CSB pre-mix group (19.1%) compared to the RUTF group (9.3%) (p = 0.003). The average weight gain up to discharge was 1.08 g kg(-1) day(-1) higher in the RUTF group [95% confidence interval: 0.46-1.70] and the length of stay was 2 weeks shorter in the RUTF group (p < 0.001). For the treatment of childhood MAM in Niger, RUTF resulted in a higher weight gain, a higher recovery rate, a shorter length of stay and a lower transfer rate to the I-TFC compared to a CSB pre-mix. This might have important implications on the efficacy and the quality of SFPs

Information content of ozone retrieval algorithms

The algorithms are characterized that were used for production processing by the major suppliers of ozone data to show quantitatively: how the retrieved profile is related to the actual profile (This characterizes the altitude range and vertical resolution of the data); the nature of systematic errors in the retrieved profiles, including their vertical structure and relation to uncertain instrumental parameters; how trends in the real ozone are reflected in trends in the retrieved ozone profile; and how trends in other quantities (both instrumental and atmospheric) might appear as trends in the ozone profile. No serious deficiencies were found in the algorithms used in generating the major available ozone data sets. As the measurements are all indirect in someway, and the retrieved profiles have different characteristics, data from different instruments are not directly comparable