The plasma physics of shock acceleration

The notion that plasma shocks in astrophysical settings can and do accelerate charged particles to high energies is not a new one. However, in recent years considerable progress has been achieved in understanding the role particle acceleration plays both in astrophysics and in the shock process itself. In this paper we briefly review the history and theory of shock acceleration, paying particular attention to theories of parallel shocks which include the backreaction of accelerated particles on the shock structure. We discuss in detail the work that computer simulations, both plasma and Monte Carlo, are playing in revealing how thermal ions interact with shocks and how particle acceleration appears to be an inevitable and necessary part of the basic plasma physics that governs collisionless shocks. We briefly describe some of the outstanding problems that still confront theorists and observers in this field.     

Results of measurements of the response of a delta-doped CCD to neutral and charged particle beams

We report the measurements of the response of a delta-doped Charge Coupled Device (CCD) in imaging mode to beams of charged and neutral particles. That is, the detector imaged the incident beam over its 1024 × 1024 pixels, integrating the number of particles counted in each pixel during the exposure period. In order to count individual particles the exposure time would have had to be reduced considerably compared to the typical ?5 s used in these studies. Our CCD thus operated in a different manner than do conventional particle detectors such as the CEM and MCP that normally are used in a particle counting mode. The measurements were carried out over an energy range from 0.8 to 30 keV. The species investigated include H, H⁺, He⁺, N⁺, N₂⁺, and Ar⁺. The energy and ion mass covered wider ranges than previous measurements for the CCD. The results of these measurements show, as in the case of the previous measurement, for a given ion the CCD response increases with energy and for a given particle energy the response decreases with increasing mass of the particle. These results are in agreement with predictions of the theory of the range of ions in solids. The results also show the possibility for the application of the delta doped CCD as a detector for low energy particle measurements for space plasma physics applications.     

The Radio Observatory on the Lunar Surface for Solar studies

The Radio Observatory on the Lunar Surface for Solar studies (ROLSS) is a concept for a near-side low radio frequency imaging interferometric array designed to study particle acceleration at the Sun and in the inner heliosphere. The prime science mission is to image the radio emission generated by Type II and III solar radio burst processes with the aim of determining the sites at and mechanisms by which the radiating particles are accelerated. Specific questions to be addressed include the following: (1) Isolating the sites of electron acceleration responsible for Type II and III solar radio bursts during coronal mass ejections (CMEs); and (2) Determining if and the mechanism(s) by which multiple, successive CMEs produce unusually efficient particle acceleration and intense radio emission. Secondary science goals include constraining the density of the lunar ionosphere by searching for a low radio frequency cutoff to solar radio emission and constraining the low energy electron population in astrophysical sources. Key design requirements on ROLSS include the operational frequency and angular resolution. The electron densities in the solar corona and inner heliosphere are such that the relevant emission occurs at frequencies below 10 MHz. Second, resolving the potential sites of particle acceleration requires an instrument with an angular resolution of at least 2°, equivalent to a linear array size of approximately 1000 m. Operations would consist of data acquisition during the lunar day, with regular data downlinks. No operations would occur during lunar night.     

Overview of the space environmental effects observed on the retrieved Long Duration Exposure Facility (LDEF).

The Long Duration Exposure Facility (LDEF), which encompassed 57 experiments with more than 10,000 test specimens, spent 69 months in low Earth orbit (LEO) before it was retrieved by the Space Shuttle in January 1990. Hundreds of LDEF investigators, after studying for over two years these retrieved test specimens and the onboard recorded data and systems hardware, have generated a unique first-hand view of the long term synergistic effects that the LEO environment can have on spacecraft. These studies have also contributed significantly toward more accurate models of the LEO radiation, meteoroid, manmade debris and atomic oxygen environments. This paper provides an overview of some of the many LDEF observations and the implications these can have on future spacecraft such as Space Station Freedom.     

The Charging of Planetary Rings

This chapter will review what is known about the charging of planetary rings, in particular the sum of the individual currents from the time-varying charge dQ/dt, of the planetary ring particle. For the smallest ring particles, in addition to checking the plasma conditions for the charging currents, one must consider if collective effects in the ring environment are relevant. Two planetary ring environments that have held a strong interest for ring scientists in the last two decades are Saturn’s spokes in the B Ring and the environment of Saturn’s E ring. Two sections of this chapter will describe these planetary ring charging environments in detail. Finally, we describe two charging effects that demonstrate areas of future studies while providing fresh examples of the intriguing effects from planetary ring charging processes.     

Nickel-hydrogen multicell common pressure vessel batterydevelopment update

Flight qualification of the multicell common pressure vessel (CPV) nickel-hydrogen (Ni-H₂) battery is discussed. The battery has completed full flight qualification, including random vibration at 19.5 g for two minutes in each axis, electrical characterization in a thermal vacuum chamber, and mass-spectroscopy vessel leak detection. A first launch is scheduled in 1992. Several design variations, ranging from 9 Ah to 125 Ah and 12 to 32 V, have been developed and prototypes fabricated. Designs for smaller capacity, smaller diameter (6.4-8.9 cm), and higher voltage (up to 100 V) are in progress. The CPV battery offers cost and weight savings of up to 30% as compared to traditional nickel-cadmium (Ni-Cd) and individual pressure vessel (IPV) Ni-H₂ batteries. The fully qualified design provided a 50% weight savings over its Nd-Cd predecessor for the same application. Its reduced volume also provides a significant advantage over IPV technology. Resistance data show a further advantage     

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.     

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。     

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.     

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.