For the 1994 Tevatron collider run, CDF has upgraded the electron and photo trigger hardware to make use of shower position and size information from the central shower maximum detector. For electrons, the upgrade has resulted in a 50% reduction in backgrounds while retaining approximately 90% of the signal. The new trigger also eliminates the background to photon triggers from single-phototube spikes.

Using neutron scattering techniques, the authors investigated the magnetic correlations in diluted antiferromagnets close to the percolation threshold in which the magnetic connectivity takes a fractal form. Recent experimental results concerning the self-similarity of the magnetic order, and magnetic excitations in two-dimensional Ising and three-dimensional Heisenberg antiferromagnets are presented.

We report on computer simulations of oscillating Woods-Saxon or cavity potentials filled with either a classical or a quantal gas of independent particles. We have now available of the order of 600 excitation histories of such gases undergoing usually one period of oscillation (but sometimes several), classified according to frequency and multipolarity of the oscillation and of the degree of diffuseness of the potential. We are still in the process of displaying and interpreting some of the results, but certain important features are already apparent. A notable finding is that, contrary to concerns sometimes voiced in the literature, the classical wall formula does not fail catastrophically when confronted with quantal calculations. This is true even for relatively small systems -- in our case 112 neutrons in doubly degenerate eigenstates. On the contrary, the wall formula, in addition to reproducing accurately the classical computer simulations, gives also an approximate account of the quantal results in the regime where it is expected to be valid, namely for not too small oscillation frequencies and not too large surface diffuseness. In those cases it is gratifying to observe that the deviations from the wall formula actually correlate (semi-quantitatively) with the wave-mechanical corrections derived by …

We have determined the inelastic magnetic response S({omega}) of UPd{sub x}cu{sub 5{minus}x} (X=1,1.5) for temperatures from 0.3 to 300 K and energies between 05 and 400 meV using the neutron time of flight technique. S({omega}) is virtually identical in the two compound, displaying marginal Fermi Liquid scaling over the entire range of temperatures, as well as scale invariant energetics.

The application of uniaxial pressure can induce elastic anisotropy in otherwise isotropic rock. We consider models based on two very different rock classes, granites and weakly consolidated granular systems. We show that these models share common underlying assumptions, that they lead to similar qualitative behavior, and that both provide a microscopic basis for elliptical anisotropy. In the granular case, we make experimentally verifiable predictions regarding the horizontally propagating modes based on the measured behavior of the vertical modes.

The indirect-drive targets being considered for inertial fusion require the driver to deposit 5 MJ on a target in less than 10 ns. This requirement can in principle be met by on beams with particle masses between 120 and 240 amu, an ion kinetic energy in the range of 6--12 GeV, and a total current in excess of 30 kA. Three strategies for generating beams with these parameters are currently being studied. European laboratories are investigating the use of low-current beams from a radio-frequency accelerator. To obtain the needed current density, these beams would be stacked and accumulated in storage rings and then directed simultaneously at the target. American researchers are developing high-current induction accelerators, and the two principal configurations under consideration are the linear driver and the ``recirculator,`` in which ion pulses pass repeatedly through the same accelerator elements. The merits of the three approaches are compared, and key physics uncertainties in each are identified.

The performance of the Ni/NiCl{sub 2} positive electrode for the Na/NiCl{sub 2} battery has been significantly improved compared to that of our earlier electrodes, representative for 1990. This improvement has been achieved by lowering the impedance and increasing the usable capacity through the use of chemical additives and a tailored electrode morphology. The improved electrode has excellent performance even at 250{degrees}C and can be recharged within one hour. The performance of this new electrode was measured by the conventional interrupted galvanostatic method and under simulated driving profiles. These measurements were used to project the performance of 40- to 60-kWh batteries built with this new electrode combined with the already highly developed sodium/{beta}{double_prime}-alumina negative electrode. These calculated results yielded a specific power of 150--400 W/kg and a specific energy of 110--200 Wh/kg for batteries with single-tube and bipolar cell designs. This high performance, along with the high cell voltage, mid-temperature operation, fast recharge capability, and short-circuited failure mode of the electrode couple, makes the Na/NiCl{sub 2} battery attractive for electric vehicle applications.

Computer animation of outdoor scenes is enhanced by realistic clouds. I will discuss several different modeling and rendering schemes for clouds, and show how they evolved in my animation work. These include transparency-textured clouds on a 2-D plane, smooth shaded or textured 3-D clouds surfaces, and 3-D volume rendering. For the volume rendering, I will present various illumination schemes, including the density emitter, single scattering, and multiple scattering models.

More than a decade ago individuals from three significant institutions in East Bay Area began discussions in response to the apprehensions that were so deep in the early 1980s. These apprehensions were a result of the intense rhetoric between the two superpowers and the casual commentary about ``limited nuclear war.`` The discussions spoke to the mortal danger as well as to the profound moral question revolving around nuclear arms. The issuance of the US Bishops` Pastoral on War and Peace in 1983 gave the group focus and momentum. The Chancellor at the University of California at Berkeley, the President of the Graduate Theological Union (the consortium of theological schools in Berkeley), and the Director of the Lawrence Livermore National Laboratory (one of the chief designers of American nuclear arms) encouraged us to complete plans for a symposium. It was an era of activism. We chose, however, to serve the theme expressed by Albert Einstein, ``Peace cannot be kept by force, it can only be achieved by understanding.`` After a decade, all of us can commend the leadership of the three institutions and the individuals involved for their perseverance. Their commitments to the pursuit of peace and to the development of …

The author discusses some legal aspects of measures at the national level to implement the Chemical Weapons Convention (CWC). These implementing measures are universal, applying not only to the few States Parties that will declare and destroy chemical weapons, but also to the many States Parties that have never had a chemical weapons program. This new need for national measures to implement multilateral arms control agreements has generated unease due to a perception that implementation may be burdensome and at odds with national law. In 1993, concerns arose that the complexity of integrating the treaty with national law would cause each nation to effectuate the Convention without regard to what other nations were doing, thereby engendering significant disparities in implementation steps among States Parties. The author discusses progress among several States in actually developing national CWC implementing measures. Implementing measures from Australia, Norway, South Africa, and Sweden were available to him in English through the PTS. He compares them in order to illustrate different approaches to national implementation that are emerging. Of course, it is important to note that this brief survey necessarily omitted examination of the existing ``background`` of other, related domestic laws that these signatories might also have …

We previously established a rapid three-dimensional assay for discrimination of normal and malignant human breast epithelial cells using a laminin-rich reconstituted basement membrane. In this assay, normal epithelial cells differentiate into well-organized acinar structures whereas tumor cells fail to recapitulate this process and produce large, disordered colonies. The data suggest that breast acinar morphogenesis and differentiation is regulated by cell-extracellular matrix (ECM) interactions and that these interactions are altered in malignancy. Here, we investigated the role of ECM receptors (integrins) in these processes and report on the expression and function of potential laminin receptors in normal and tumorigenic breast epithelial cells. Immmunocytochemical analysis showed that normal and carcinoma cells in a three-dimensional substratum express profiles of integrins similar to normal and malignant breast tissues in situ. Normal cells express {alpha}1, {alpha}2, {alpha}3, {alpha}6, {beta}1 and {beta}4 integrin subunits, whereas breast carcinoma cells show variable losses, disordered expression, or down regulation of these subunits. Function-blocking experiments using inhibitory antiintegrin subunit antibodies showed a >5-fold inhibition of the formation of acinar structures by normal cells in the presence of either anti-{beta}1 or anti-{alpha}3 antibodies, whereas anti-{alpha}2 or -{alpha}6 had little or no effect. In experiments where collagen type I gels were used …

We report high-resolution measurements of electron impact excitation and ionization cross sections for the Na-like ions Kr{sup 25+} and Xe{sup 43+}. Ions with ionization states centered on the Na-like configurations were produced in an electron beam ion trap (EBIT) using electrons with energies below the L shell ionization thresholds. The Na-like ions were exposed to an electron beam with an energy between 3 and 7 keV. The Na- and Ne-like ions were then extracted and their intensities measured as a function of the electron beam energy. Theoretical ionization cross sections were calculated using relativistic distorted wave methods. Complex resonance structures that appear in the computed cross sections are observed in the experimental results. These results are the first experimental observation of resonant-excitation-double-autoionization (REDA) in highly charged high-Z ions.

At the Savannah River Site, low-level radioactive decontaminated salt solution is mixed with slag, flyash, and cement to form a grout-like material called ``Saltstone``. The Saltstone is poured into concrete vaults constructed at the Saltstone Disposal Facility (SDF). The impact of SDF on groundwater has been studied in a radiological performance assessment (PA). Sophisticated groundwater models were used to predict the groundwater flow and contaminant transport problems. The modeling effort was divided into two parts: the unsaturated-zone model and the saturated zone model. One of the major performance objectives is to show that the impacted groundwater will be in compliance with the Safe Drinking Water Act.

We study both the complexity and approximability of various graph and combinatorial problems specified using two dimensional narrow periodic specifications (see [CM93, HW92, KMW67, KO91, Or84b, Wa93]). The following two general kinds of results are presented. (1) We prove that a number of natural graph and combinatorial problems are NEXPTIME- or EXPSPACE-complete when instances are so specified; (2) In contrast, we prove that the optimization versions of several of these NEXPTIME-, EXPSPACE-complete problems have polynomial time approximation algorithms with constant performance guarantees. Moreover, some of these problems even have polynomial time approximation schemes. We also sketch how our NEXPTIME-hardness results can be used to prove analogous NEXPTIME-hardness results for problems specified using other kinds of succinct specification languages. Our results provide the first natural problems for which there is a proven exponential (and possibly doubly exponential) gap between the complexities of finding exact and approximate solutions.

In August 1979, Halbach submitted a paper entitled ``Design of Permanent Multipole Magnets with Oriented Rare Earth Cobalt Material.`` In this paper, he presented a novel method of generating multipole magnetic fields using non-intuitive geometrical arrangements of permanent magnets. In subsequent publications, he further defined these concepts. Of particular interest to one of the authors (RFP) was the special magnet array that generated a uniform dipole field. In 1990 Post proposed the construction of an electric machine (a motor/generator) using a dipole field based on Klaus Halbach`s array of permanent magnets. He further proposed that such a system should be employed as an integral part of ``an electromechanical battery`` (EMB), i.e., a modular flywheel system to be used as a device for storing electrical energy, as an alternative to the electrochemical storage battery. This paper reviews Halbach`s theory for the generation of a dipole field using an array of permanent magnet bars, presents a simple analysis of a family of novel ``ironless`` electric machines designed using the dipole Halbach array, and describes the results obtained when they were tested in the laboratory.

Theories suggest there is a link between protamine concentrations in individual sperm and male fertility. Previously, biochemical analyses have used pooled samples containing millions of sperm to determine protamine concentrations. These methods have not been able to determine what percentage of morphologically normal sperm are biochemically defective and potentially infertile. Nuclear microscopy has been utilized to measure elemental profiles at the single sperm level. By measuring the amount of phosphorus and sulfur, the total DNA and protamine content in individual sperm from fertile bull and mouse semen have been determined. These values agree with results obtained from other biochemical analyses. Nuclear microscopy shows promise for measuring elemental profiles in the chromatin of individual sperm. The technique may be able to resolve theories regarding the importance of protamines to male fertility and identify biochemical defects responsible for certain types of male infertility.