[en] The purpose of this work is to characterize groundwater flow and contaminant transport at the Shoal underground nuclear test through numerical modeling using site-specific hydrologic data. The ultimate objective is the development of a contaminant boundary, a model-predicted perimeter defining the extent of radionuclide-contaminated groundwater from the underground test throughout 1,000 years at a prescribed level of confidence. This boundary will be developed using the numerical models described here, after they are approved for that purpose by DOE and NDEP

[en] The FRX-C/T experiment is a combination of the FRX-C theta-pinch, which forms field-reversed configuration (FRC) compact toroids, with a dc solenoid section, where the FRC (typical plasma parameters of n = 1-3 x 10¹⁵ cm^-3, T/sub e/+T/sub i/ = 0.2-0.7 keV, tau/sub E/ approx. 100 μs) is translated and trapped in an axial dc guide field B₀. The experiment combines pulsed, high-voltage technology for the theta-inch formation region with a dc energized magnet set for the translation section. Five stainless steel tank modules form the translation vacuum chamber. A B₀ field of < 8 kG is generated by the thirty-nine water-cooled pancake magnets of the dc magnet set that is mounted concentric with the vacuum vessel. A dc magnetic mirror (ratio < 5) is at the end of the translation region. The dc magnets are powered by a computer controlled and monitored 0.3 kV, 2.5 MW dc power supply. A computer monitored 78 channel digital thermal switch system and 128 channel analog thermistor system ensure that the coils do not overheat. The 1248-turn dc solenoid is 0.17 m away from the 100-kV theta-pinch coil requiring precautionary measures to minimize transient high voltages induced onto the dc solenoid. A helical quadrupole magnet has been added to the translation vessel to produce a weak B-field that suppresses the n=2 rotational instability

[en] We explore the feasibility and astrophysical consequences of a new long-range U(1) gauge field ('dark electromagnetism') that couples only to dark matter, not to the standard model. The dark matter consists of an equal number of positive and negative charges under the new force, but annihilations are suppressed if the dark-matter mass is sufficiently high and the dark fine-structure constant α-circumflex is sufficiently small. The correct relic abundance can be obtained if the dark matter also couples to the conventional weak interactions, and we verify that this is consistent with particle-physics constraints. The primary limit on α-circumflex comes from the demand that the dark matter be effectively collisionless in galactic dynamics, which implies α-circumflex < or approx. 10^-3 for TeV-scale dark matter. These values are easily compatible with constraints from structure formation and primordial nucleosynthesis. We raise the prospect of interesting new plasma effects in dark-matter dynamics, which remain to be explored.

[en] The FRX-C/T experiment is a combination of the FRX-C Θ-pinch, which forms field-reversed configuration (FRC) compact toroids, with a dc solenoid section, where the FRC (typical plasma parameters of n = 1-3 x 10/sup 15/ cm/sup -3/, T/sub e/+T/sub i/ = 0.2-0.7 keV, tau/sub E/ ≅ 100 μs) is translated and trapped in an axial dc guide field B/sub o/. The experiment combines pulsed, high-voltage technology for the Θ-pinch formation region with a dc energized magnet set for the translation section. Five stainless steel tank modules form the translation vacuum chamber. A B/sub o/ field of ≤ 8kG is generated by the thirty-nine water-cooled pancake magnets of the dc magnet set that is mounted concentric with the vacuum vessel. A dc magnetic mirror (ratio ≤ 5) is at the end of the translation region. The dc magnets are powered by a computer controlled and monitored 0.3 kV, 2.5 MW dc power supply. A computer monitored 78 channel digital thermal switch system and 128 channel analog thermistor system ensure that the coils do not overheat

[en] Controlling carrier transport in light-emitting polymers is extremely important for their efficient use in organic opto-electronic devices. Here, we show that the interactions between single-wall carbon nanotubes (SWNTs) and conjugated polymers can be used to modify the overall mobility of charge carriers within nanotube- polymer nanocomposites. By using unique, double-emitting organic light-emitting diodes (DE-OLEDs), we characterized the hole transport within electroluminescent nanocomposites (nanotubes in poly (m-phenylene vinylene-co-2,5-dioctoxy-p-phenylene) or PmPV). We showed, using this idea, that single devices with color tunability can be fabricated. SWNTs in PmPV are seen to be responsible for hole trapping, leading to shifts in the emission wavelengths. Our results could lead to improved organic optical amplifiers, semiconducting devices, and displays.

[en] We have used ultrahigh vacuum scanning tunneling microscopy (STM) to study chromium (Cr)-filled carbon nanotubes. STM micrographs show filled tubes to be less than 1 nm in height, while transmission electron microscopy indicates that Cr-filled naotubes are multiwalled with diameters generally over 10 nm. In this paper, we demonstrate that the small apparent heights are due to the STM tip status, which also accounts for the topographic anomalies observed

[en] A search for pairs of high p_T prompt photons produced in hydrogen by a 280 GeV/c incident π^- beam has been carried out using a fine-grained electromagnetic calorimeter and the Omega spectrometer at the CERN SPS. Clear evidence for the existence of such events is found with a six standard deviation signal for p_T > 3.0 GeV/c. The cross sections are consistent with beyond leading order QCD calculations. A discussion on the determination of α_s is also presented. 18 refs., 7 figs., 7 tabs

[en] Pseudomonas chlororaphis phage 201φ2-1 is a relative of Pseudomonas aeruginosa myovirus φKZ. Phage 201φ2-1 was examined by complete genomic sequencing (316,674 bp), by a comprehensive mass spectrometry survey of its virion proteins and by electron microscopy. Seventy-six proteins, of which at least 69 have homologues in φKZ, were identified by mass spectrometry. Eight proteins, in addition to the major head, tail sheath and tail tube proteins, are abundant in the virion. Electron microscopy of 201φ2-1 revealed a multitude of long, fine fibers apparently decorating the tail sheath protein. Among the less abundant virion proteins are three homologues to RNA polymerase β or β' subunits. Comparison between the genomes of 201φ2-1 and φKZ revealed substantial conservation of the genome plan, and a large region with an especially high rate of gene replacement. The φKZ-like phages exhibited a two-fold higher rate of divergence than for T4-like phages or host genomes