The authors recently developed an analytic theory of cumulative multibunch beam breakup that includes a linear variation of transverse focusing across the bunch train. The focusing variation saturates the exponential growth of the beam breakup and establishes an algebraic decay of the transverse bunch displacement versus bunch number. In this paper they illustrate how the focusing variation works to suppress multibunch beam breakup, as well as how the mechanism scales with accelerator and beam parameters.

This paper presents a new algorithm for the decomposition of a multi-domain protein into individual structural domains. The underlying principle used is that residue-residue contacts are denser within a domain than between domains.

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A recent, popular method of finding promoter sequences is to look for conserved motifs up-stream of genes clustered on the basis of expression data. This method presupposes that the clustering is correct. Theoretically, one should be better able to find promoter sequences and create more relevant gene clusters by taking a unified approach to these two problems. We present a likelihood function for a sequence-expression model giving a joint likelihood for a promoter sequence and its corresponding expression levels. An algorithm to estimate sequence-expression model parameters using Gibbs sampling and Expectation/Maximization is described. A program, called kimono, that implements this algorithm has been developed and the source code is freely available over the internet.

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Studies of the influences of temperature, hydrostatic pressure, dc biasing field and frequency on the dielectric constant ({epsilon}{prime}) and loss (tan {delta}) of single crystal [pb (Zn{sub 1/3}Nb{sub 2/3})O{sub 3}]{sub 0.905} (PbTiO{sub 3}){sub 0.095}, or PZN-9.5PT for short, have provided a detailed view of the ferroelectric (FE) response and phase transitions of this technologically important material. While at 1 bar, the crystal exhibits on cooling a cubic-to-tetragonal FE transition followed by a second transition to a rhombohedral phase, pressure induces a FE-to-relaxer crossover, the relaxer phase becoming the ground state at pressures {ge}5 kbar. Analogy with earlier results suggests that this crossover is a common feature of compositionally-disordered soft mode ferroelectrics and can be understood in terms of a decrease in the correlation length among polar domains with increasing pressure. Application of a dc biasing electric field at 1 bar strengthens FE correlations, and can at high pressure re-stabilize the FE response. The pressure-temperature-electric field phase diagram was established. In the absence of dc bias the tetragonal phase vanishes at high pressure, the crystal exhibiting classic relaxor behavior. The dynamics of dipolar motion and the strong deviation from Curie-Weiss behavior of the susceptibility in the high temperature cubic phase are …

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While several arguments can be proposed against the existence of particles with energy in excess of (3--5) x 10{sup 19} eV in the cosmic ray spectrum, these particles are actually observed and their origin seeks for an explanation. After a description of the problems encountered in explaining these ultra-high energy cosmic rays (UHECRs) in the context of astrophysical sources, the authors review the so-called Top-Down (TD) Models, in which UHECRs are the result of the decay of very massive unstable particles, possibly created in the Early Universe. Particular emphasis will be given to the signatures of the TD models, likely to be accessible to upcoming experiments like Auger.

A time-dependent cohesive zone model is employed to model adhesive failure and grain-boundary cracking. Through the incorporation of viscoelasticity and evolving damage, the viscoelastic cohesive zone model (VCZM) yields a time-dependent critical energy release rate. A double-cantilever beam configuration is investigated. Crack growth curves are presented for the Xu-Needleman and VCZM model. In addition, a fifty-five grain polycrystal is simulated in compression. Time-dependent grain boundary prying and sliding result in inter-granular separation parallel to the major axis of loading.

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The authors presents the status of searches for large extra spacetime dimensions and technicolor at the Fermilab Tevatron. The author emphasizes recent D0 limits on graviton-mediated exchange processes, and CDF searches for new b{anti b} resonances and third-generation leptoquarks.

The authors show that Compton scattering can be used to cool TeV-scale muon beams, and derive analytical expressions for the equilibrium transverse angular spread, longitudinal energy spread, and power requirements. They find that a factor of a few thousand reduction in emittance is possible for a 3 TeV muon collider.

This report discusses the effects of age and sex on the retention and excretion of {sup 137}Cs in the body in a cross section of the general population over a four-year period.

In this paper we review the present picture of km halo in proton linacs. Space-charge forces acting in mismatched beams have been identified as a major cause of beam-halo. We present a definition of halo based on a ratio of moments of the distribution of the beam coordinates. We find from our initial studies that for halo detined in this way, a beam can have rms emittance growth without halo growth, but halo growth is always accompanied by rms emittance growth. We describe the beam-halo experiment that is in preparation at Los Alamos, which will address questions about the beam profiles, maximum particle amplitudes, and rms emittance growth associated with the halo.

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The Department of Energy Partnership for a New Generation of Vehicles has shown that, by lowering overall weight, the use of carbon fiber composites could dramatically decrease domestic vehicle fuel consumption. For the automotive industry to benefit from carbon fiber technology, fiber production will need to be substantially increased and fiber price decreased to $7/kg. To achieve this cost objective, alternate precursors to pitch and polyacrylonitrile (PAN) are being investigated as possible carbon fiber feedstocks. Additionally, sufficient fiber to provide 10 to 100 kg for each of the 13 million cars and light trucks produced annually in the U.S. will require an increase of 5 to 50-fold in worldwide carbon fiber production. High-volume, renewable or recycled materials, including lignin, cellulosic fibers, routinely recycled petrochemical fibers, and blends of these components, appear attractive because the cost of these materials is inherently both low and insensitive to changes in petroleum price. Current studies have shown that a number of recycled and renewable polymers can be incorporated into melt-spun fibers attractive as carbon fiber feedstocks. Highly extrudable lignin blends have attractive yields and can be readily carbonized and graphitized. Examination of the physical structure and properties of carbonized and graphitized fibers indicates the …

The DIII-D Thomson system measures electron density and temperature with eight pulsed ND:YAG lasers along three paths through the plasma vessel. The components of the Thomson system are absolutely calibrated so the measurements can be combined into a single profile from a normalized plasma radius ({rho}) of about 0.1 to the edge of the plasma. A monochromator calibration and opto-electronic calibration measure the detectors' absolute sensitivity to background and pulsed light. A Rayleigh scattering calibration and transmission calibrations measure the transmission of light to the detectors. The calibration systems are being upgraded to reduce the effect of systematic errors on the temperature and density measurements. The systematic errors can be checked by a comparison of overlapping channels and estimated from fits to the profiles. The contributions of the systematic uncertainties relative to the statistical uncertainties of the measurement are discussed through simulations and experimental data.

Confined quantum many-body systems of a given particle number exhibit a variety of intrinsic shape characteristics as a function of increasing external field and internal thermal excitation. The shell model is an important tool for the theoretical description of these various structures and transitions in nuclei. Another system in which correlations beyond the mean field may play an important role is semiconductor quantum dots. In this Proceedings, the author compares nuclei and quantum dots and their various deformation properties. The author reports on shell-model calculations in nuclei and some recent mean-field calculations of the thermal properties of quantum dots.

Surface depletion was investigated in laboratory- and plant-scale distillation units with mixing by natural convection or by mechanical surface agitation. A model was developed for predicting the degree of surface depletion during the distillation of metals from bismuth as a function of temperature, still pot dimensions, and degree of agitation. This paper discusses those findings.