Article on benzo[ghi]perylene versus pyrene as solute probes for polarity determination of liquid organic salts used in chromatography.

It has been well documented that summer heat islands increase the demand for air conditioning. Several studies have suggested developing guidelines to mitigate this negative effect, on both micro- and meso-scales. Reducing summer heat islands saves cooling energy, reduces peak demand, and reduces the emission of CO{sub 2} from electric power plants. This paper summarizes some of the efforts to quantify the effects of techniques to reduce heat islands. In particular, the authors summarize simulations they have made on the effects of plating trees and switching to light colored surfaces in cities. The results indicate that these techniques effectively reduce building cooling loads and peak power in selected US cities, and are the cheapest way to save energy and reduce CO{sub 2} emissions. This paper compares the economics of technologies to mitigate summer heat islands with other types of conservation measures. The authors estimate the cost of energy conserved by planting trees and recoating surfaces on a national level and compare it with the cost of energy conserved by increasing efficiencies in electrical appliances and cars. Early results indicate that the cost of energy saved by controlling heat islands is less than 1{cents}/kWh, more attractive than efficient electric appliances ({approximately} …

The cost of structural components in a large superconducting coil may well exceed the coil and cryostat cost. As a result, the idea of constructing a system composed of two different coil types assembled in such a way that the forces balance and reduce the total structural requirement is oft proposed. A suitable geometry has never been found for the fundamental reason that there can be no force compensated solution. In this paper, the general problem is presented and an analysis of the energy stored and stresses produced in the structure are described in a fundamental way. Finally, the relation between structural mass M and stored energy E, M {ge} {rho}E/{sigma}{sub w}, that is valid for all, magnetic systems is developed, where {rho} is the density of the structure and {sigma}{sub w} is the working stress in the structure.

Article from the Hastings Center Report about the legal difficulties facing AIDS patients in getting medical care.

Biomass gasification and pyrolysis have the potential to make a significant impact on energy supplies in the United States and have demonstrated their commercial potential in many projects around the country. The environmental aspects of biomass gasification need to be defined to assure that the technology makes its maximum impact on energy supplies. One area that needs further development is characterization and treatment of the tar byproduct from gasifiers and pyrolyzers. This paper examines the effect of the type of gasifier/pyrolyzer and the processing conditions on the yield and properties of tars and condensates. End use limitations for tars are discussed. Wet scrubbing is the most common method of tar removal from gases. The scrub liquor will require treatment to remove organics before it can be disposed. Pacific Northwest Laboratory (PNL) is developing a catalytic tar destruction process that will treat the hot, raw gas from the gasifier and convert the tars to gas. The process increases the gas yield and cold gas efficiency of the gasification process, produces a clean gas that can be used for many applications, and produces a clean condensate that can be disposed with minimal treatment. 10 refs., 2 figs., 1 tab.

The use of powerful microwave sources provide unique opportunities for novel and efficient heating and current-drive schemes in the electron-cyclotron and lower-hybrid ranges of frequencies. Free- electron lasers and relativistic klystrons are new sources that have a number of technical advantages over conventional, lower-intensity sources; their use can lead to improved current-drive efficiencies and better penetration into a reactor-grade plasma in specific cases. This paper reports on modeling of absorption and current drive, in intense-pulse and quasilinear regimes, and on analysis of parametric instabilities and self-focusing. 16 refs., 2 figs.

In the last few years there has been significant progress in ICF research in laboratories in the United States and elsewhere. These advances have occurred in areas that range from demonstrating an innovative laser beam smoothing techniques important for both directly and indirectly driven ICF, to achieving a more complete understanding of capsule implosions and related physics. This progress has been possible because of the capabilities provided by the ICF laser-target facilities currently in operation and the new developments in diagnostics, particularly for measurements of the implosion process and the conditions in the compressed capsule core. Both of these topics, facilities and selected new diagnostics capabilities in the US ICF Program, are summarized in this paper. 32 refs., 19 figs., 6 tabs.

The outstanding unresolved issue of the highly successful standard model is the origin of electroweak symmetry breaking and of the mechanism that determines its scale, namely the vacuum expectation value (vev)v that is fixed by experiment at the value v = 4m//sub w//sup 2///g/sup 2/ = (..sqrt..2G/sub F/)/sup /minus/1/ approx. = 1/4 TeV. In this talk I will discuss aspects of two approaches to this problem. One approach is straightforward and down to earth: the search for experimental signatures, as discussed previously by Pierre Darriulat. This approach covers the energy scales accessible to future and present laboratory experiments: roughly (10/sup /minus/9/ /minus/ 10/sup 3/)GeV. The second approach involves theoretical speculations, such as technicolor and supersymmetry, that attempt to explain the TeV scale. 23 refs., 5 figs.

This paper discusses some historical aspects of particle physics. (LSP)

Sensitive radio-frequency (rf) amplifiers based on dc Superconducting QUantum Interface Devices (SQUIDS) are available for frequencies up to 200 MHz. At 4.2 K, the gain and noise temperature of a typical tuned amplifier are 18.6 +- 0.5 dB and 1.7 +- 0.5 K at 93 MHz. These amplifiers are being applied to a series of novel experiments on nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR). The high sensitivity of these amplifiers was demonstrated in the observation of ''nuclear spin noise'', the emission of photons by /sup 35/Cl nuclei in a state of zero polarization. In the more conventional experiments in which one applies a large rf pulse to the spins, a Q-spoiler, consisting of a series array of Josephson junctions, is used to reduce the Q of the input circuit to a very low value during the pulse. The Q-spoiler enables the circuit to recover quickly after the pulse, and has been used in an NQR experiment to achieve a sensitivity of about 2 /times/ 10/sup 16/ nuclear Bohr magnetons in a single free precession signal with a bandwidth of 10 kHz. In a third experiment, a sample containing /sup 35/Cl nuclei was placed in a capacitor and …

Collisionless reconnection of magnetic field lines depends upon electron inertia effects and details of the electron and ion distribution functions, thus requiring a kinetic description of both. Though traditional explicit PIC techniques provide this description in principle, they are severely limited in parameters by time step constraints. This parameter regime has been expanded by using the recently constructed 2.5 D electromagnetic code AVANTI in this work. The code runs stably with arbitrarily large {Delta}t and is quite robust with respect to large fluctuations occurring due to small numbers of particles per cell. We have found several qualitatively new features. The reconnection process is found to occur in distinct stages: early spontaneous reconnection fed by the free energy of an initial anisotropy in the electron component, coalescence of the resulting small-scale filaments of electron current, accompanied by electron jetting, and oscillatory flow of electrons through the magnetic X-point, superposed on continuing nonlinear growth of ion-mediated reconnection. The time evolution of stage is strongly dependent on M{sub i}/m{sub e}. 12 refs., 6 figs.

We have developed a new test procedure for evaluating filter penetrations as low as 10/sup /minus/9/ at 0.1-..mu..m particle diameter. In comparison, the present US nuclear filter certification test has a lower penetration limit of 10/sup /minus/5/. Our new test procedure is unique not only in its much higher sensitivity, but also in avoiding the undesirable effect of clogging the filter. Our new test procedure consists of a two-step process: (1) We challenge the test filter with a very high concentration of heterodisperse aerosol for a short time while passing all or a significant portion of the filtered exhaust into an inflatable bag; (2) We then measure the aerosol concentration in the bag using a new laser particle counter sensitive to 0.07-..mu..m diameter. The ratio of particle concentration in the bag to the concentration challenging the filter gives the filter penetration as a function of particle diameter. The bad functions as a particle accumulator for subsequent analysis to minimize the filter exposure time. We have studied the particle losses in the bag over time and find that they are negligible when the measurements are taken within one hour. We also compared filter penetration measurements taken in the conventional direct-sampling method …

In most geothermal reservoirs large-scale permeability is dominated by fractures, while most of the heat and fluid reserves are stored in the rock matrix. Early-time fluid production comes mostly from the readily accessible fracture volume, while reservoir behavior at later time depends upon the ease with which fluid and heat can be transferred from the rock matrix to the fractures. Methods for modeling flow in fractured porous media must be able to deal with this matrix-fracture exchange, the so-called interporosity flow. This paper reviews recent work at Lawrence Berkeley Laboratory on numerical modeling of nonisothermal multiphase flow in fractured porous media. We also give a brief summary of simulation applications to problems in geothermal production and reinjection. 29 refs., 1 fig.

Emissions and atmospheric concentrations of several trace gases important to atmospheric chemistry are known to have increased substantially over recent decades. Solar flux variations and the atmospheric nuclear test series are also likely to have affected stratospheric ozone. In this study, the LLNL two-dimensional chemical-radiative-transport model of the troposphere and stratosphere has been applied to an analysis of the effects that these natural and anthropogenic influences may have had on global ozone concentrations over the last three decades. In general, model determined species distributions and the derived ozone trends agree well with published analyses of land-based and satellite-based observations. Also, the total ozone and ozone distribution trends derived from CFC and other trace gas effects have a different response with latitude than the derived trends from solar flux variations, thus providing a ''signature'' for anthropogenic effects on ozone. 24 refs., 5 figs.

After being informed that radioactive material from the Chernobyl nuclear power plant had been discovered on the clothing of workers at a Swedish reactor site, the United States Department of Energy requested that the Atmospheric Release Advisory Capability (ARAC) evaluate both the extent and the magnitude of the accident (Dickerson and Sullivan, 1987). ARAC is a real-time emergency response service that specializes in the regional assessment of radiological accidents using advanced dispersion models. While we possessed a sizable inventory of computer models with which to address this problem, we lacked an operational tool that could be used with confidence in determining the fate of airborne radioactivity beyond about 500 km. As an outgrowth of this experience, we began to explore the spatial limits of applicability of our Advection-Diffusion Particle-In-Cell (ADPIC) model (Lange, 1978). At the same time, we began testing a hybrid version of this model that uses the Air Force Global Weather Central's Northern Hemisphere Whole Mesh Grid of wind velocities as input. In combination, these models can provide, potentially, a response capability that extends from tens of kilometers to the entire Northern Hemisphere. 7 refs., 6 figs.

Fermilab's Advanced Computer Program (ACP) has been developing highly cost effective, yet practical, parallel computers for high energy physics since 1984. The ACP's latest developments are proceeding in two directions. A Second Generation ACP Multiprocessor System for experiments will include $3500 RISC processors each with performance over 15 VAX MIPS. To support such high performance, the new system allows parallel I/O, parallel interprocess communication, and parallel host processes. The ACP Multi-Array Processor, has been developed for theoretical physics. Each $4000 node is a FORTRAN or C programmable pipelined 20 MFlops (peak), 10 MByte single board computer. These are plugged into a 16 port crossbar switch crate which handles both inter and intra crate communication. The crates are connected in a hypercube. Site oriented applications like lattice gauge theory are supported by system software called CANOPY, which makes the hardware virtually transparent to users. A 256 node, 5 GFlop, system is under construction. 10 refs., 7 figs.

The Modular High-Temperature Gas-Cooled Reactor (MHTGR) is an advanced power plant concept which has been under design definition since 1984. The design utilizes basic high-temperature gas-cooled reactor features of ceramic fuel, helium coolant and a graphite moderator which have been under development for 30 years. The geometric arrangement of the reactor vessels, the core and the heat removal components has been selected to exploit the inherent characteristics associated with high temperature materials. The design utilizes passively safe features which provide a higher margin of safety and investment protection than current generation reactors. The design has been evaluated to be economically attractive relative to modern coal fired plants. The design and development program is a cooperative effort by the US government, the utilities and the nuclear industry. 8 refs., 4 figs., 4 tabs.

The 1970's and 1980's can be considered the third stage in the explosive development of condensed matter physics. After the very intensive research of the 1930's and 1940's, which followed the formulation of quantum mechanics, and the path-breaking activity of the 1950's and 1960's, the problems being faced now are much more complex and not always susceptible to simple modelling. The (subjectively) open problems discussed here are: high temperature superconductivity, its properties and the possible new mechanisms which lead to it; the integral and fractional quantum Hall effects; new forms of order in condensed-matter systems; the physics of disorder, especially the problem of spin glasses; the physics of complex anisotropic systems; the theoretical prediction of stable and metastable states of matter; the physics of highly correlated states (heavy fermions); the physics of artificially made structures, in particular heterostructures and highly metastable states of matter; the determination of the microscopic structure of surfaces; and chaos and highly nonlinear phnomena. 82 refs.

Detector systems for RHIC experiments are invariably going to be large and complex. Thus it behooves the planners to incorporate elements that have little need for adjustment, calibration and correction to the produced data. For example, if power, size and cost considerations permit, time can be digitized directly (i.e. with counters, shift registers, etc.) where no adjustments, calibrations or corrections are required. The circuit either works correctly or not at all. This kind of circuit behavior is extremely valuable in detectors with 10/sup 5/ or more channel elements. In analog to digital conversion applications, direct conversion (i.e. flash ADC) may be prohibitive in cost, size and power. Here major effort must be given to minimize the magnitude of offset and conversion gain variance. Where possible self correction and adjustment should be applied at the subsystem level.

An x-ray calibration facility for use in the 0.2--25 keV region is described. The facility employs several types of specially modified sources and detectors to produce and detect both line and continuum radiation in this energy range. We describe an inexpensive commercial x-ray source which has been modified for efficient high intensity operation as well as production of x-rays up to 25 keV. We also describe a system that utilizes multilayer mirrors alone or in a double Bragg geometry to select an energy bandpass. This system is controlled by a microcomputer which translates and rotates the multilayers to provide an easily selectable monochromatic beam with good resolution over a broad energy range. A long focal length Kirkpatrick--Baez mirror pair has been coupled to a pivoting beam line in order to accurately characterize gratings for use in soft x-ray astronomy. The beam line is scanned through the various grating orders. All aspects of the facility incorporate high degree of flexibility so that a wide variety of calibrations can be easily performed. 12 refs., 5 figs.

The CERN experiment WA80 studies ultrarelativistic heavy ion collisions by calorimetry and charged particle measurements over a large fraction of 4..pi... Here I want to concentrate on a closer study of nucleus nucleus collisions and recent results from the lead glass spectrometer Saphir. 6 refs., 5 figs.

By combining the results of the hydrodynamic code CON1D and the beam propagation code LASER, we investigate the propagation of high-energy laser beams through vaporizing metallic aerosols in the regime for which the plasma generation becomes important. An effective plasma absorption coefficient allows us to set up a coupled system of equations describing the system consisting of the beam and vapor. 14 refs., 5 figs.

A unique high-efficiency particulate air (HEPA) filter medium has been developed for applications in high temperature and high pressure environments. This filter medium is a composite made from quartz and stainless-steel fibers that have been sintered together. The composite medium has the same efficiency and pressure drop as standard HEPA glass media, but has four times the tensile strength and can operate continuously at temperatures up to 500/degree/C. In a conventional HEPA, the binder burns out above 250/degree/C and the medium loses its strength; our composite filter medium has no comparable loss of strength even at 500/degree/C. 8 refs., 8 figs., 1 tab.

Radiative processes strongly effect equilibrium trace gas concentrations both directly, through photolysis reactions, and indirectly through temperature and transport processes. We have used the LLNL 2-D chemical-radiative-transport model to investigate the net sensitivity of equilibrium ozone concentrations to several changes in radiative forcing. Doubling CO/sub 2/ from 300 ppmv to 600 ppmv resulted in a temperature decrease of 5 K to 8 K in the middle stratosphere along with an 8% to 16% increase in ozone in the same region. Replacing our usual shortwave scattering algorithms with a simplified Rayleigh algorithm led to a 1% to 2% increase in ozone in the lower stratosphere. Finally, modifying our normal CO/sub 2/ cooling rates by corrections derived from line-by-line calculations resulted in several regions of heating and cooling. We observed temperature changes on the order of 1 K to 1.5 K with corresponding changes of 0.5% to 1.5% in O/sub 3/. Our results for doubled CO/sub 2/ compare favorably with those by other authors. Results for our two perturbation scenarios stress the need for accurately modeling radiative processes while confirming the general validity of current models. 15 refs., 5 figs.