Results of the 1978 NASA/JPL balloon flight solar cell calibration program

The 1978 scheduled solar cell calibration balloon flight was successfully completed. Thirty six modules were carried to an altitude of above 36 kilometers. Recovery of telemetry and flight packages was without incident. These calibrated standard cells are used as reference standards in simulator testing of cells and arrays with similar spectral response characteristics. The factors affecting the spectral transmission of the atmosphere at various altitudes are summarized

Optimal Compression of Floating-point Astronomical Images Without Significant Loss of Information

We describe a compression method for floating-point astronomical images that gives compression ratios of 6 -- 10 while still preserving the scientifically important information in the image. The pixel values are first preprocessed by quantizing them into scaled integer intensity levels, which removes some of the uncompressible noise in the image. The integers are then losslessly compressed using the fast and efficient Rice algorithm and stored in a portable FITS format file. Quantizing an image more coarsely gives greater image compression, but it also increases the noise and degrades the precision of the photometric and astrometric measurements in the quantized image. Dithering the pixel values during the quantization process can greatly improve the precision of measurements in the images. This is especially important if the analysis algorithm relies on the mode or the median which would be similarly quantized if the pixel values are not dithered. We perform a series of experiments on both synthetic and real astronomical CCD images to quantitatively demonstrate that the magnitudes and positions of stars in the quantized images can be measured with the predicted amount of precision. In order to encourage wider use of these image compression methods, we have made available a pair of general-purpose image compression programs, called fpack and funpack, which can be used to compress any FITS format image.Comment: Accepted PAS

Lossless Astronomical Image Compression and the Effects of Noise

We compare a variety of lossless image compression methods on a large sample of astronomical images and show how the compression ratios and speeds of the algorithms are affected by the amount of noise in the images. In the ideal case where the image pixel values have a random Gaussian distribution, the equivalent number of uncompressible noise bits per pixel is given by Nbits =log2(sigma * sqrt(12)) and the lossless compression ratio is given by R = BITPIX / Nbits + K where BITPIX is the bit length of the pixel values and K is a measure of the efficiency of the compression algorithm. We perform image compression tests on a large sample of integer astronomical CCD images using the GZIP compression program and using a newer FITS tiled-image compression method that currently supports 4 compression algorithms: Rice, Hcompress, PLIO, and GZIP. Overall, the Rice compression algorithm strikes the best balance of compression and computational efficiency; it is 2--3 times faster and produces about 1.4 times greater compression than GZIP. The Rice algorithm produces 75%--90% (depending on the amount of noise in the image) as much compression as an ideal algorithm with K = 0. The image compression and uncompression utility programs used in this study (called fpack and funpack) are publicly available from the HEASARC web site. A simple command-line interface may be used to compress or uncompress any FITS image file.Comment: 20 pages, 9 figures, to be published in PAS

Hillforts and Power in the British Post-Roman West: A GIS Analysis of Dinas Powys

The (re)occupation of hillforts was a distinctive feature of post-Roman Europe in the fifth to seventh centuries AD. In western and northern Britain, hillforts are interpreted as power centres associated with militarized elites, but research has paid less attention to their landscape context, hence we know little about the factors that influenced their siting and how this facilitated elite power. Geographic Information Systems (GIS) provide opportunities for landscape research, but are constrained by limitations of source data and the difficulty of defining appropriate parameters for analysis. This article presents a new methodology that combines data processing and analytical functions in GIS with techniques and principles drawn from ‘traditional’ landscape archaeology. A case study, focused on Dinas Powys, suggests that the strategic siting of this hillfort facilitated control over the landscape and has wider implications for our understanding of patterns of power in post-Roman Britain

Detection of Pharmaceuticals, Personal Care Products (PPCPS) and Illicit Drugs in Wastewater Treatment Plants and Urban River Systems

ABSTRACT DETECTION OF PHARMACEUTICALS AND PERSONAL CARE PRODUCTS (PPCPS) AND ILLICIT DRUGS IN WASTEWATER TREATMENT PLANTS AND URBAN RIVER SYSTEMS by Mary L Seaman The University of Wisconsin-Milwaukee, 2023 Under the Supervision of Professor Todd Miller, PhD Pharmaceuticals, personal care products (PPCPs) and illicit drugs are a threat to human health and the aquatic environment globally. Their usage and consumption is rapidly increasing potentially due to an aging population, the development of new drugs, the overprescribing of prescription drugs and easier accessibility of drugs legally and illegally prescribed. These compounds enter wastewater treatment plants influent through urine or feces, pass through the stages of treatment with some compounds not being removed and ending up in the effluent and ultimately in the aquatic environment. In addition to human consumption, PPCPs are introduced into the environment through veterinary use from livestock, and where concentrated animal feeding operations (CAFOs) are located. Wastewater treatment plants (WWTPs) effluent are the major source of these compounds into the environment. The wastewater effluent is discharged into rivers, streams, or lake systems, and the biosolids are spread on fields for fertilizer. WWTPs are known to not adequately remove these compounds and as a result there is a continuous supply of these compounds to the environment. There are few studies on the long-term effects of these compounds in the environment. The contaminants most often detected in wastewater treatment effluent are antibiotics, epileptic drugs, analgesics, herbicides, opioids, and recreational drugs. This dissertation uses an alternative extraction method compared to the standard solid phase extraction (SPE) method used in most of the literature. In Chapters 2 and 3, sixty diverse compounds were analyzed from samples taken from influent, effluent, surface water and sludge from two WWTPs that discharge their effluent into the largest freshwater lake in the State of Wisconsin. Data were further analyzed by percent remaining, removal efficiency and seasonality. Chapter 4 surveyed PPCPs and illicit drugs from six urban river systems, using the alternative extraction method from Chapters 2 and 3. In addition, removal efficiency, percent remaining, and seasonality were also studied. There is an increasing trend towards urbanization and lifestyle changes, increasing health ailments such as cardiovascular disease, diabetes, and illicit drug use. With rapid urbanization, brings about an increase in contamination of water. The PPCPs and illicit drugs may be transferred to the water by rainfall, climate changes, infrastructure breakdown of private sceptic systems, and release of gray water. Stressors in the surrounding water environment may be channel form, cement encasements, the type of community surrounding the water whether it be industrial, manufacturing, agricultural, retail, etc.The alternative extraction method was successful in detecting the 60 diverse compounds but there were limitations on percent recovery values for certain compounds

Helicoidal surfaces with constant anisotropic mean curvature

We study surfaces with constant anisotropic mean curvature which are invariant under a helicoidal motion. For functionals with axially symmetric Wulff shapes, we generalize the recently developed twizzler representation of Perdomo to the anisotropic case and show how all helicoidal constant anisotropic mean curvature surfaces can be obtained by quadratures