The critics return to flight

A former astronaut justifies human space exploration and provides a rebuttal to criticism of continued exploration. The discussion includes examples of skeptics' arguments and examples of NASA achievements that have had direct economic and social impacts on the United States.     

应用绿色半导体量子点进行乳腺癌原位成像

乳腺癌是癌症中引起妇女死亡的首要因素。本文采用绿色量子点作为荧光显色材料,建立了一种用于早期乳腺癌诊断的原位成像技术。利用生物素标记的抗HER2／neu抗体与乳腺癌细胞表面表达的HER2结合的特点,然后用偶联绿色量子点的链霉亲和素作为荧光检测标记物,与HER2抗原抗体复合物中的生物素发生特异结合,检测出乳腺癌细胞的存在。结果表明,在荧光显微镜下用绿色量子点原位显色的乳腺癌细胞,相对有机染料组显色亮度增强,故检测灵敏度有所提高。     

They came in peace for all mankind: popular culture as a reflection of public attitudes to space

It has always been clear that one of the main driving forces behind the space race was Cold War propaganda. But just what impact did it have on ‘the minds of men everywhere’? This paper presents a survey of the impact of space exploration on popular culture in Britain in the 1950s and 1960s, concentrating chiefly on the cinema. Before the launch of Sputnik in 1957, although space was present in popular culture, it was generally aimed at a specialised audience. In the 1960s, interest in space became widespread and reached unexpected corners of popular culture such as pop music. This popular success had dangerous consequences, however: when public interest waned in the early 1970s, the immense cost of the Moon landings could no longer be justified on propaganda grounds and the project was massively reduced.     

ATS-6 Radio Beacon Experiment: The First Year

The Radio Beacon Experiment is designed to measure the total electron content and ionospheric content between the satellite and any observer within its field of view. Since Applications Technology Satellite-6 (ATS-6) is visible from about 43 percent of the Earth's surface, an international community of observers have made measurements using it. The radio parameters have to be measured to an accuracy of a few percent, which requires good system calibration and stability. The spaceborne beacon transmits signals on frequencies of 40, 140, and 360 MHz with amplitude modulations of 1 MHz and/or 0.1 MHz for the measurement of modulation phase, Faraday rotation, and amplitude. The overall system objectives and requirements are discussed along with the design of the ATS-6 transmitter and the receiver in Boulder, Colo. The role of the principal investigator in the context of the international program is considered with particular reference to the joint National Oceanic and Atmospheric Administration (NOAA)/Max Planck Institute (MPI) observation program. Monthly median hourly values of total content, plasmaspheric content, and shape factor show distinct diurnal and seasonal variations. A specific event is described to illustrate the use of a spaced receiver network.     

Radioisotope detection and identification at high speeds using passive sensors

A network of radiation sensors for the protection of a military base against radiological/nuclear threats has been integrated in a testbed. Two key subsystems of this network are the array of sensitive radiation detectors and the subsystem for notifying the operators of radiation events. The alarm/alert notification subsystem automatically issues notifications to the command post in real-time. The resulting reporting to the command post appears to be adequate for non-technical operational personnel. The CONOPS for the protection system relies on the sensitive detection and identification of all radioactive sources well before the transporting vehicles reach the base gates. This is a unique feature of this protection system. Discriminating sodium-iodide detectors, in conjunction with plastic scintillators and neutron detectors comprise a high-performance detection subsystem. The use of various correlation techniques has permitted the demonstration of the detection of source strengths of tens of /spl mu/Ci moving at highway speeds and at several meters separation. A companion algorithm identifies the detected radioisotope when sufficient counts are available.     

Modeling gravity effects on water retention and gas transport characteristics in plant growth substrates

Growing plants to facilitate life in outer space, for example on the International Space Station (ISS) or at planned deep-space human outposts on the Moon or Mars, has received much attention with regard to NASA’s advanced life support system research. With the objective of in situ resource utilization to conserve energy and to limit transport costs, native materials mined on Moon or Mars are of primary interest for plant growth media in a future outpost, while terrestrial porous substrates with optimal growth media characteristics will be useful for onboard plant growth during space missions. Due to limited experimental opportunities and prohibitive costs, liquid and gas behavior in porous substrates under reduced gravity conditions has been less studied and hence remains poorly understood. Based on ground-based measurements, this study examined water retention, oxygen diffusivity and air permeability characteristics of six plant growth substrates for potential applications in space, including two terrestrial analogs for lunar and Martian soils and four particulate substrates widely used in reduced gravity experiments. To simulate reduced gravity water characteristics, the predictions for ground-based measurements (1 − g) were scaled to two reduced gravity conditions, Martian gravity (0.38 − g) and lunar gravity (0.16 − g), following the observations in previous reduced gravity studies. We described the observed gas diffusivity with a recently developed model combined with a new approach that estimates the gas percolation threshold based on the pore size distribution. The model successfully captured measured data for all investigated media and demonstrated the implications of the poorly-understood shift in gas percolation threshold with improved gas percolation in reduced gravity. Finally, using a substrate-structure parameter related to the gaseous phase, we adequately described the air permeability under reduced gravity conditions.     

EXOSAT and EINSTEIN High Resolution Images of the Small Magellanic Cloud

In order to obtain optical identifications and further information about the X-ray emission of sources discovered in the EINSTEIN IPC survey of the Small Magellanic Cloud (SMC), we have used the EXOSAT CMA and EINSTEIN HRI at selected positions. These observations have so far resulted in several identifications (including 4 stellar objects with m_v 14 to 21 and a Seyfert galaxy), and the discovery of two new X-ray sources. Medium energy X-rays (2–6 keV) have been detected from the brightest SNR in the SMC, 1E0102.2-7219. We present here an initial report of these results.     

Magnetostriction: revealing the unknown

Giant magnetostrictive materials began to be developed during the 1970s. One material in particular was developed by the Naval Ordnance Lab for use in sonar applications. TERFENOL-D, named for its primary constituents of terbium, iron and dysprosium and place of invention, generates usable strains of 1 mil per inch of material in an applied magnetic field, TERFENOL-D actuators provide 220 N to 880 N of force. Oil well logging shear wave generation using TERFENOL-D sources is accomplished with 1 A of current, providing 3,000 N of force. TERFENOL-D exhibits inverse magnetostriction, or the Villari effect, making it able to provide on demand nondestructive evaluation and inspection of structures, commonly referred to as magnetotagging     

Mapping of hydrothermally altered rocks using airborne multispectral scanner data,Marysvale, Utah,mining district

Multispectral data covering an area near Marysvale, Utah, collected with the airborne National Aeronautics and Space Administration (NASA) 24-channel Bendix multispectral scanner, were analyzed to detect areas of hydrothermally altered, potentially mineralized rocks. Spectral bands were selected for analysis that approximate those of the Landsat 4 Thematic Mapper and which are diagnostic of the presence of hydrothermally derived products. Hydrothermally altered rocks, particularly volcanic rocks affected by solutions rich in sulfuric acid, are commonly characterized by concentrations of argillic minerals such as alunite and kaolinite. These minerals are important for identifying hydrothermally altered rocks in multispectral images because they have intense absorption bands centered near a wavelength of 2.2 μm. Unaltered volcanic rocks commonly do not contain these minerals and hence do not have the absorption bands.A color-composite image was constructed using the following spectral band ratios: 1.6μm/2.2μm, 1.6μm/0.48μm, and 0.67μm/1.0μm. The particular bands were chosen to emphasize the spectral contrasts that exist for argillic versus non-argillic rocks, limonitic versus nonlimonitic rocks, and rocks versus vegetation, respectively. The color-ratio composite successfully distinguished most types of altered rocks from unaltered rocks. Some previously unrecognized areas of hydrothermal alteration were mapped. The altered rocks included those having high alunite and/or kaolinite content, siliceous rocks containing some kaolinite, and ash-fall tuffs containing zeolitic minerals. The color-ratio-composite image allowed further division of these rocks into limonitic and nonlimonitic phases. The image did not allow separation of highly siliceous or hematitically altered rocks containing no clays or alunite from unaltered rocks.A color-coded density slice image of the 1.6μm/2.2μm band ratio allowed further discrimination among the altered units. Areas containing zeolites and some ash-fall tuffs containing montmorillonite were readily recognized on the color-coded density slice as having less intense 2.2-μm absorption than areas of highly altered rocks. The areas of most intense absorption, as depicted in the color-coded density slice, are dominated by highly altered rocks containing large amounts of alunite and kaolinite. These areas form an annulus, approximately 10 km in diameter, which surrounds a quartz monzonite intrusive body of Miocene age. The patterns of most intense alteration are interpreted as the remnants of paleohydrothermal convective cells set into motion during the emplacement of the central intrusive body.     

Anthropogenic and natural causes of twentieth century temperature change

We analyse spatio-temporal patterns of near-surface temperature change to provide an attribution of twentieth century climate change. We apply an ``optimal detection' methodology to seasonal and annual data averaged over a range of spatial and temporal scales. We find that solar effects may have contributed significantly to the warming in the first half of the century although this result is dependent on the reconstruction of total solar irradiance that is used. In the latter half of the century, we find that anthropogenic increases in greenhouses gases are largely responsible for the observed warming, balanced by some cooling due to anthropogenic sulphate aerosols, with no evidence for significant solar effects.