Center motions of nonoverlapping condensates coupled by long-range dipolar interaction in bilayer and multilayer stacks

We investigate the effect of anisotropic and long-range dipole-dipole interaction (DDI) on the center motions of nonoverlapping Bose-Einstein condensates (BEC) in bilayer and multilayer stacks. In the bilayer, it is shown analytically that while DDI plays no role in the in-phase modes of center motions of condensates, out-of-phase mode frequency ($\omega_o$) depends crucially on the strength of DDI ($a_d$). At the small-$a_d$ limit, $\omega_o^2(a_d)-\omega_o^2(0)\propto a_d$. In the multilayer stack, transverse modes associated with center motions of coupled condensates are found to be optical phonon like. At the long-wavelength limit, phonon velocity is proportional to $\sqrt a_d$.Comment: 7 pages, 5 figure

Solar-powered pump

A solar powered pump particularly suited for intermittently delivering a stream of water is reported. The pump is characterized by a housing adapted to be seated in a source of water having a water discharge port disposed above the water line of the source, a sump including a valved inlet port through which water is introduced to the sump, disposed beneath the water line, a displacer supported for vertical reciprocation in said housing, an air passageway extended between the vertically spaced faces of the displacer, and a tipple disposed adjacent to the water discharge port adapted to be filled in response to a discharge of water from the housing. Air above a displacer is expanded in response to solar energy impinging on the housing and transferred into pressurizing relation with the sump for forcing water from the sump

Easy insert, easy release toggle bolt fastener

Releasable pin-type toggle bolt fastener is constructed so that, when positioned in hole, toggle action prevents its removal and locknut anchors it firmly in place. Fastener is easily removed by loosening locknut and retraction of toggle wings

Quantum cosmological Friedman models with a Yang-Mills field and positive energy levels

We prove the existence of a spectral resolution of the Wheeler-DeWitt equation when the matter field is provided by a Yang-Mills field, with or without mass term, if the spatial geometry of the underlying spacetime is homothetic to $\R[3]$. The energy levels of the resulting quantum model, i.e., the eigenvalues of the corresponding self-adjoint Hamiltonian with a pure point spectrum, are strictly positive.Comment: 9 pages, v3: minor corrections to bring it in line with the published versio

Evaluation of Experimental Populations and Glandular-Haired Varieties of Alfalfa for Alfalfa Blotch Leafminer (Diptera: Agromyzidae) Feeding Injury

Following the spread of the alfalfa blotch leafminer, Agromyza frontella (Rondani) (Diptera: Agromyzidae), into Minnesota and Wisconsin U.S.A. during 1994-1997, three field trials were conducted in Minnesota to assess the potential for leafminer resistance among several sources of alfalfa (Medicago sativa), germplasm. In 1998, 86 entries were evaluated, most of which were experimental populations. In addition, six commercial varieties of alfalfa were evaluated. Of the six varieties, four had been bred for various levels of glandular-hair expression, specifically for resistance to the potato leafhopper, Empoasca fabae (Harris) (Homoptera: Cicadellidae). In two of three trials, we found no significant differences in leafmining injury to trifoliolates among the 86 entries, or among glandular-haired and traditional commercial varieties. At one location, ‘Arrest,’ ‘Ameriguard 301,’ and ‘DK 121 HG’ incurred significantly less pinhole injury than the glandular-haired variety ‘5347 LH’ or the commercial standard, ‘5454.’ However, after accounting for both pinhole and leafmining injury, only ‘Arrest’ and ‘Ameriguard 301’ had less injury than ‘5347 LH,’ ‘DK 121 HG,’ or the standard ‘5454.’ The low levels of resistance to A. frontella injury, among glandular-haired commercial alfalfa varieties and numerous experimental populations M. sativa, confirm the need for alternative A. frontella management strategies such as biological control and possible manipulation of harvest schedules

Effects of biases in domain wall network evolution. II. Quantitative analysis

Domain walls form at phase transitions which break discrete symmetries. In a cosmological context they often overclose the universe (contrary to observational evidence), although one may prevent this by introducing biases or forcing anisotropic evolution of the walls. In a previous work [Correia {\it et al.}, Phys.Rev.D90, 023521 (2014)] we numerically studied the evolution of various types of biased domain wall networks in the early universe, confirming that anisotropic networks ultimately reach scaling while those with a biased potential or biased initial conditions decay. We also found that the analytic decay law obtained by Hindmarsh was in good agreement with simulations of biased potentials, but not of biased initial conditions, and suggested that the difference was related to the Gaussian approximation underlying the analytic law. Here we extend our previous work in several ways. For the cases of biased potential and biased initial conditions we study in detail the field distributions in the simulations, confirming that the validity (or not) of the Gaussian approximation is the key difference between the two cases. For anisotropic walls we carry out a more extensive set of numerical simulations and compare them to the canonical velocity-dependent one-scale model for domain walls, finding that the model accurately predicts the linear scaling regime after isotropization. Overall, our analysis provides a quantitative description of the cosmological evolution of these networks.Comment: 12 pages, 7 figure

Probes for measuring noise current in an electronic cable

Electromagnetic interference in deep-space network receiver is often caused by stray coupling from power lines. These stray signals create potential differences between ground terminals, which leads to excessive noise in receiver circuits. Pair of probes detect and measure noise currents in conductors