Multi-instantons in seven dimensions

We consider the self-dual Yang-Mills equations in seven dimensions. Modifying the t'Hooft construction of instantons in $d=4$, we find $N$-instanton $7d$ solutions which depend on $8N$ effective parameters and are $E_{6}$-invariant.Comment: 9 pages, LaTeX, no figure

Digital control of magnetic bearings supporting a multimass flexible rotor

The characteristics of magnetic bearings used to support a three mass flexible rotor operated at speeds up to 14,000 RPM are discussed. The magnetic components of the bearing are of a type reported in the literature previously, but the earlier analog controls were replaced by digital ones. Analog-to-digital and digital-to-analog converters and digital control software were installed in an AT&T PC. This PC-based digital controller was used to operate one of the magnetic bearings on the test rig. Basic proportional-derivative control was applied to the bearings, and the bearing stiffness and damping characteristics were evaluated. Particular attention is paid to the frequency dependent behavior of the stiffness and damping properties, and comparisons are made between the actual controllers and ideal proportional-derivative control

Self-dual Yang-Mills fields in pseudoeuclidean spaces

The self-duality Yang-Mills equations in pseudoeuclidean spaces of dimensions $d\leq 8$ are investigated. New classes of solutions of the equations are found. Extended solutions to the D=10, N=1 supergravity and super Yang-Mills equations are constructed from these solutions.Comment: 9 pages, LaTeX, no figure

Transient absorption and reshaping of ultrafast XUV light by laser-dressed helium

We present a theoretical study of transient absorption and reshaping of extreme ultraviolet (XUV) pulses by helium atoms dressed with a moderately strong infrared (IR) laser field. We formulate the atomic response using both the frequency-dependent absorption cross section and a time-frequency approach based on the time-dependent dipole induced by the light fields. The latter approach can be used in cases when an ultrafast dressing pulse induces transient effects, and/or when the atom exchanges energy with multiple frequency components of the XUV field. We first characterize the dressed atom response by calculating the frequency-dependent absorption cross section for XUV energies between 20 and 24 eV for several dressing wavelengths between 400 and 2000 nm and intensities up to 10^12 W/cm^2. We find that for dressing wavelengths near 1600 nm, there is an Autler-Townes splitting of the 1s ---> 2p transition that can potentially lead to transparency for absorption of XUV light tuned to this transition. We study the effect of this XUV transparency in a macroscopic helium gas by incorporating the time-frequency approach into a solution of the coupled Maxwell-Schr\"odinger equations. We find rich temporal reshaping dynamics when a 61 fs XUV pulse resonant with the 1s ---> 2p transition propagates through a helium gas dressed by an 11 fs, 1600 nm laser pulse.Comment: 13 pages, 8 figures, 1 table, RevTeX4, revise

Generalized Parton Distributions in Full Lattice QCD

We present recent results on generalized parton distributions from dynamical lattice QCD calculations. Our set of twelve different combinations of couplings and quark masses allows for a preliminary study of the pion mass dependence of the transverse nucleon structure.Comment: 8 pages, 5 figures; Talk presented by Ph.H. at Light-Cone 2004, Amsterdam, 16 - 20 Augus

DRC-1339 AND DRC-2698 RESIDUES IN STARLINGS: PRELIMINARY EVALUATION OF THEIR EFFECTS ON SECONDARY HAZARD POTENTIAL

DRC-1339 (3-chloro-4-methylbenzenamine HCI) is the active ingredient in Starlicide Complete, a commercial bait used to control starlings (Sturnus vulgaris) at animal feedlots throughout the U.S. Because of the recent widespread use of this product, par- ticularly within the wintering range of many raptors, they and other avian or mammalian scavenger or predator species may be exposed to large numbers of dead or dying star- lings and blackbirds (Icteridae) throughout the winter roosting season (November-March). Acute toxicity data are available for five species of raptors and a number of mammals indicating that DRC-1339 or its primary toxic metabolite DRC-2698 (N-(3-chloro-4-methylphenyl) acetamide, CAT), a potential roost toxicant, are only moderately toxic (100-300 mg/kg) to these animals. However, there are some avian and mammalian scavengers or predators to which these compounds are considerably more toxic (i.e., cats, owls, magpies). Secondary hazards have not been observed when DRC-1339 killed starlings were fed to three raptor species for as long as 141 days and to domestic cats for seven days (DeCino, Cunningham and Schafer 1966; Holler et al. 1979, unpubl, manuscript); however, the direct long-term effects of both chemicals have not been determined on raptors or other predatory or scavenger species. In order to decide if long-term studies are needed on predator or scavenger species, it is necessary to estimate accurately the degree of expected exposure to DRC-1339 and DRC-2698under actual use conditions. Since exposure will depend primarily upon the amount of these chemicals that remains in bird carcasses from bait ingestion until death, the metabolic or excretion rate of DRC-1339 and DRC-2698 must be known in target and at-risk, nontarget bird species. Although considerable data are available to determine the metabolic or excretion rate of DRC-1339 in target birds, some of these data are conflicting. We are therefore presenting the preliminary results of some of our current research with DRC-1339 and DRC-2698

Spontaneous Symmetry Breaking with Abnormal Number of Nambu-Goldstone Bosons and Kaon Condensate

We describe a class of relativistic models incorporating finite density of matter in which spontaneous breakdown of continuous symmetries leads to a lesser number of Nambu-Goldstone bosons than that required by the Goldstone theorem. This class, in particular, describes the dynamics of the kaon condensate in the color-flavor locked phase of high density QCD. We describe the spectrum of low energy excitations in this dynamics and show that, despite the presence of a condensate and gapless excitations, this system is not a superfluid.Comment: 5 pages, 1 figure, REVTeX. Minor revisions made and 2 new references added. To appear in Phys. Rev. Let