Article on nip, a symbiotic Medicago truncatula mutant that forms root nodules with aberrant infection threads and plant defense-like response.

Article on LIN, a Medicago truncatula gene required for nodule differentiation and persistence of rhizobial infections.

The self-irradiation damage generated by alpha decay of plutonium results in the formation of lattice defects, helium, and uranium atoms. Over time, microstructural evolution resulting from the self-irradiation may influence the physical and mechanical properties of the material. In order to assess microstructural changes, we have developed and applied procedures for the specimen preparation, handling, and transmission electron microscopy characterization of Pu alloys. These transmission electron microscopy investigations of Pu-Ga alloys ranging in age up to 42-years old reveal the presence of nanometer-sized helium bubbles. The number density of bubbles and the average size have been determined for eight different aged materials.

Polymer injection has been used in reservoirs to alleviate contrasting permeability zones to enhance oil recovery (EOR). Polymer technology relies mainly on the use of polyacrylamides cross-linked by a hazardous metal or organic. Contemporary polymer plugging has investigated the stimulation of in-situ microorganisms to produce polymers (Jenneman et. al., 2000) and the use of biocatalysts to trigger gelling (Bailey et. al., 2000). The use of biological polymers are advantageous in that they can block high permeability areas, are environmentally friendly, and have potential to form reversible gels without the use of hazardous cross-linkers. Recent efforts have produced a reactive alkaline-soluble biopolymer from Agrobacterium species ATCC # 31749 that gels upon decreasing the pH of the polymeric solution. Microbial polymers are of interest due to their potential cost savings, compared to conventional use of synthetic chemical polymers. Numerous microorganisms are known to produce extracellular polysaccharides. One microbiological polymer of interest is curdlan, â - (1, 3) glucan, which has demonstrated gelling properties by a reduction in pH. The focus of this study was to determine the impact an alkaline-soluble biopolymer can have on sandstone permeability.

Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, results from three-dimensional numerical simulations of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams, 9(2), 209 (1991)] are presented. Using the multi-physics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J.A. Greenough, J. Comp. Phys. 184, 53 (2003)], the late nonlinear instability evolution, including transition to turbulence, is considered for various multimode perturbation spectra. The 3D post-transition state differs from the 2D result, but the process of transition proceeds similarly in both 2D and 3D. The turbulent mixing transition results in a reduction in the growth rate of the mixing layer relative to its pre-transition value and, in the case of the bubble front, relative to the 2D result. The post-transition spike front velocity is approximately the same in 2D and 3D. Implications for hydrodynamic mixing in core-collapse supernova are discussed.

Tunnels in jointed rocks can be subjected to severe dynamic loads because of rock bursts, coal bumps, and large earthquakes. A series of 3-dimensional simulations was performed, based on discrete element analysis to gain insights into the parameters that influence the response of such tunnels. The simulations looked at the effect of joint set orientation, the effect of joint spacing, the effect of pulse shape for a given displacement, and the influence of using rigid versus deformable blocks in the analyses. The results of this modeling were also compared to field evidence of dynamic tunnel failures. This comparison reinforced the notion that 3-dimensional discrete element analysis can capture very well the kinematics of structures in jointed rock under dynamic loading.

We find clusters and superclusters of galaxies using the Data Release 1 of the Sloan Digital Sky Survey. We determine the luminosity function of clusters and find that clusters in a high-density environment have a luminosity a factor of {approx}5 higher than in a low-density environment. We also study clusters and superclusters in numerical simulations. Simulated clusters in a high-density environment are also more massive than those in a low-density environment. Comparison of the density distribution at various epochs in simulations shows that in large low-density regions (voids) dynamical evolution is very slow and stops at an early epoch. In contrast, in large regions of higher density (superclusters) dynamical evolution starts early and continues until the present; here particles cluster early, and by merging of smaller groups very rich systems of galaxies form.

Most small wind turbines furl (yaw or tilt out of the wind) as a means of limiting power and rotor speeds in high winds. The Small Wind Research Turbine (SWRT) testing project was initiated in 2003 with the goal of better characterizing both small wind turbine loads (including thrust) and dynamic behavior, specifically as they relate to furling. The main purpose of the testing was to produce high-quality data sets for model development and validation and to help the wind industry further their understanding of small wind turbine behavior. Testing was conducted on a modified Bergey Excel 10-kW wind turbine. A special shaft sensor was designed to measure shaft loads including thrust, torque, and shaft bending. Analysis of 10-minute mean data showed a strong correlation between furling and center of thrust location, as calculated from the shaft-bending and thrust measurements. Data were collected for three different turbine configurations that included a change in the lateral furling offset and the blades. An analysis of inflow conditions indicated that organized atmospheric turbulence had some impact on furling.

We present a stable and convergent method for the computation of flows of DNA-laden fluids in microchannels with complex geometry. The numerical strategy combines a ball-rod model representation for polymers tightly coupled with a projection method for incompressible viscous flow. We use Cartesian grid embedded boundary methods to discretize the fluid equations in the presence of complex domain boundaries. A sample calculation is presented showing flow through a packed array microchannel in 2D.

No-core shell model (NCSM) calculations using ab initio effective interactions are very successful in reproducing the experimental nuclear spectra. While a great deal of work has been directed toward computing effective interactions from bare nucleon-nucleon (NN) and three-nucleon forces, less progress has been made in calculating the effective operators. Thus, except for the relative kinetic energy, the proton radius, and the NN pair density, all investigations have used bare operators. We apply the Lee-Suzuki procedure to general two-body operators, investigating the importance of the approximations involved. In particular we concentrate on the limitations of the two-body cluster approximation.

The results of a comprehensive infrared imaging search for the putative 0.06 M{sub {circle_dot}} astrometric companion to the 4.4 pc white dwarf van Mannen 2 are reported. Adaptive optics images acquired at 3.8 {micro}m reveal a diffraction limited core of 0.09 inch and no direct evidence of a secondary. Models predict that at 5 Gyr, a 50 M{sub J} brown dwarf would be only 1 magnitude fainter than van Maanen 2 at this wavelength and the astrometric analysis suggested a separation of 0.2 inch. In the case of a chance alignment along the line of sight, a 0.4 mag excess should be measured. An independent photometric observation at the same wavelength reveals no excess. In addition, there exist published ISO observations of van Maanen 2 at 6.8 {micro}m and 15.0 {micro}m which are consistent with photospheric flux of a 6750 K white dwarf. If recent brown dwarf models are correct, there is no substellar companion with T{sub eff} {approx}> 500 K.

Two points in our recent article on Edward Teller's scientific life (Physics Today, August 2004, page 45) require correction. In our description of Teller's students, we incorrectly stated that Arthur Kantrowitz's thesis was on the generation of hypersonic molecular beams. Actually, his thesis was on heat capacity lags in gas dynamics. Kantrowitz's invention of high intensity sources for molecular beams came later in his career. Maurice Goldhaber has emphasized that the situation with respect to possible nuclear resonances in ({gamma},n) or ({gamma},fission) reactions was quite unclear at the time of George C. Baldwin and G. Stanley Klaiber's papers on these reactions. This was because the rapid rise of their yield to a prominent peak with increasing energy, followed by a slower fall off was then thought to have been due to the competition between the rapidly rising density of nuclear states and the eventual domination of other reaction channels at higher energies. Goldhaber realized, however, that there could be an analogy between a possible collective nuclear resonance and the restrahl resonance (essentially the transverse optical phonon mode) in polar crystals. Goldhaber sought out Teller because of his paper with Russell Lyddane and Robert Sachs, relating the restrahl frequency to the …

Isopiestic vapor-pressure measurements were made at 298.15 K for aqueous NaCl + SrCl{sub 2} solutions, using NaCl(aq) as the reference standard. The measurements for these ternary solutions were made at NaCl ionic strength fractions of y{sub 1} = 0.17066, 0.47366, and 0.82682 for the water activity range 0.9835 {ge} a{sub w} {ge} 0.8710. Our results, and those from two previous isopiestic studies, were combined and used with previously determined parameters for NaCl(aq) and those for SrCl{sub 2}(aq) determined here to evaluate the mixing parameters{sup S}{Theta}{sub Na,Sr} = (0.0562 {+-} 0.0007) kg {center_dot} mol{sup -1} and {Psi}{sub Na,Sr,Cl} = -(0.00705 {+-} 0.00017) kg{sup 2} {center_dot} mol{sup -2} for an extended form of Pitzer's ion-interaction model. These model parameters are valid for ionic strengths of I {le} 7.0 mol {center_dot} kg{sup -1}, where higher-order electrostatic effects have been included in the mixture model. If the fitting range is extended to the saturated solution molalities, then {sup S}{Theta}{sub Na,Sr} = (0.07885 {+-} 0.00195) kg {center_dot} mol{sup -1} and {Psi}{sub Na,Sr,Cl} = -(0.01230 {+-} 0.00033) kg{sup 2} {center_dot} mol{sup -2}. The extended ion-interaction model parameters obtained from available isopiestic data for SrCl{sub 2}(aq) at 298.15 K yield recommended values of the water activities and …

We present some phenomenology of a new class of intersecting D-brane models. Soft SUSY breaking terms for these models are calculated in the complex structure (u)-moduli dominant SUSY breaking approach (in type IIA). In this case, the dependence of the soft terms on the Yukawas and Wilson lines drops out. These soft terms have a different pattern compared to the usual heterotic string models. Phenomenological implications for dark matter are discussed.

Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and that model the energy confinement of the plasma. The physics of magnetic reconnection during spheromak formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code. The dimensional, simulation results are compared to data from the SSPX spheromak experiment at the Lawrence Livermore National Laboratory. The simulation results are tracking the experiment with increasing fidelity (e.g., improved agreement with measurements of the magnetic field, fluctuation amplitudes, and electron temperature) as the simulation has been improved in its representations of the geometry of the experiment (plasma gun and flux conserver), the magnetic bias coils, and the detailed time dependence of the current source driving the plasma gun, and uses realistic parameters. The simulations are providing a better understanding of the dominant physics in SSPX, including when the flux surfaces close and the mechanisms limiting the efficiency of electrostatic drive.

The radiocarbon calibration curve, IntCal04, extends back to 26 cal kBP. While several high resolution records exist beyond this limit, these data sets exhibit discrepancies one to another of up to several millennia. As a result, no calibration curve for the time range 26-50 cal kBP can be recommended as yet, but in this paper the IntCal04 working group compares the available data sets and offers a discussion of the information that they hold.

The probability density function for wave propagating in a straight perfect electrical conductor (PEC) rough wall tunnel is deduced from the mathematical models of the random electromagnetic fields. The field propagating in caves or tunnels is a complex-valued Gaussian random processing by the Central Limit Theorem. The probability density function for single modal field amplitude in such structure is Ricean. Since both expected value and standard deviation of this field depend only on radial position, the probability density function, which gives what is the power distribution, is a radially dependent function. The radio channel places fundamental limitations on the performance of wireless communication systems in tunnels and caves. The transmission path between the transmitter and receiver can vary from a simple direct line of sight to one that is severely obstructed by rough walls and corners. Unlike wired channels that are stationary and predictable, radio channels can be extremely random and difficult to analyze. In fact, modeling the radio channel has historically been one of the more challenging parts of any radio system design; this is often done using statistical methods. In this contribution, we present the most important statistic property, the field probability density function, of wave propagating in …

We present results and prospects for searches for rare B and D meson decays with final state dimuons, including B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -}, B{sub d}{sup 0} {yields} {mu}{sup +}{mu}{sup -}, and D{sup 0} {yields} {mu}{sup +}{mu}{sup -}. B0 Upper limits on the branching fractions are compared to previous CDF measurements, recent results from the B factories and theoretical expectations. We also report on new measurements of production and decay properties of the X(3872) particle, discovered in 2003 by the Belle Collaboration. New results on the measurement of the relative branching fraction for the Cabibbo suppressed decay B{sup +} {yields} J/{psi}{pi}{sup +} {Beta}(B{sup +} {yields} J/{psi}{pi}{sup +})/{Beta}(B{sup +} {yields} J/{psi}K{sup +}) are presented too. The presented results are based on the analyses of 70 to 220 pb{sup -1} of data collected by the CDF II detector in p{bar p} collisions at {radical}s = 1.96 GeV at Fermilab Tevatron.

A new object-oriented Minimization package is available for distribution in the same manner as CLHEP. This package, designed for use in HEP applications, has all the capabilities of Minuit, but is a re-write from scratch, adhering to modern C++ design principles. A primary goal of this package is extensibility in several directions, so that its capabilities can be kept fresh with as little maintenance effort as possible. This package is distinguished by the priority that was assigned to C++ design issues, and the focus on producing an extensible system that will resist becoming obsolete.

Bulk damage sites in frequency conversion crystals scatter and/or absorb laser light leading to interference and downstream intensification .We find that laser induced bulk damage sites in DKDP exhibit a 'shell' of structurally and/or chemically modified material surrounding a central core as indicated by SEM and optical micrographs and micro Raman spectral maps. We hypothesize that the modified material has been shock wave densified and estimate the amount of densification and its effect on scattering. A simple model indicates that densification of several percent is likely and that the scattering cross section may be larger than the geometric area of the inner core by an order of magnitude.

A new technique is developed for the derivation of the Wess-Zumino-Witten terms of gauged chiral lagrangians. We start in D = 5 with a pure (mesonless) Yang-Mills theory, which includes relevant gauge field Chern-Simons terms. The theory is then compactified, and the effective D = 4 lagrangian is derived using lattice techniques, or ''deconstruction'', where pseudoscalar mesons arise from the lattice Wilson links. This yields the WZW term with the correct Witten coefficient by way of a simple heuristic argument. We discover a novel WZW term for singlet currents, that yields the full Goldstone-Wilczek current, and a U(1) axial current for the skyrmion, with the appropriate anomaly structures. A more detailed analysis is presented of the dimensional compactification of Yang-Mills in D = 5 into a gauged chiral lagrangian in D = 4, heeding the consistency of the D = 4 and D = 5 Bianchi identities. These dictate a novel covariant derivative structure in the D = 4 gauge theory, yielding a field strength modified by the addition of commutators of chiral currents. The Chern-Simons term of the pure D = 5 Yang-Mills theory then devolves into the correct form of the Wess-Zumino-Witten term with an index (the analogue …

We demonstrate single-shot x-ray laser induced time-of-flight photoelectron spectroscopy on semiconductor and metal surfaces with picosecond time resolution. The LLNL COMET compact tabletop x-ray laser source provides the necessary high photon flux (>10{sup 12}/pulse), monochromaticity, picosecond pulse duration, and coherence for probing ultrafast changes in the city, chemical and electronic structure of these materials. Static valence band and shallow core-level photoemission spectra are presented for ambient temperature Ge(100) and polycrystalline Cu foils. Surface contamination was removed by UV ozone cleaning prior to analysis. In addition, the ultrafast nature of this technique lends itself to true single-state measurements of shocked and heated materials. Time-resolved electron time-of-flight photoemission results for ultra-thin Cu will be presented.

Searches for the electroweak production of single top quarks have been started at the Fermilab Tevatron proton-antiproton collider using Run II data by both the D0 and CDF collaborations. Using a dataset of approximately 160pb{sup -1}, neither experiment finds evidence for Single Top production and sets 95% C.L. upper limits on the production cross section. The D0 limits are 19pb on the s-channel production, 25pb on the t-channel production, and 23pb on the combined s+t-channel production. The CDF limits are 8.5pb on the t-channel production and 13.7pb on the combined s+t-channel production.

High energy and nuclear physics experiments need tracking devices with excellent spatial precision and readout speed in the face of ever-higher track densities and increased radiation environments. The new generation of hybrid pixel detectors (arrays of silicon diodes bump bonded to arrays of front-end electronic cells) is a technology able to meet these challenges. We report the first results of the BTeV silicon pixel detector beam test carried out at Fermilab in summer 2004. Tests were performed using a 120 GeV/c proton beam incident on a 6 planes pixel detector telescope. The last prototype developed for the BTeV experiment (FPIX2) is tested in the middle of the telescope. There is no external trigger and events were built using the time-stamp information provided by the readout chips.