19,633 research outputs found

    Effect of White Spruce Release on Subsequent Defoliation by the Yellowheaded Spruce Sawfly, Pikonema Alaskensis (Hymenoptera: Tenthredinidae)

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    Hand release of 22 5-year-old white spruce, Picea glauca (Moench) Voss, dramatically increased the amount of defoliation by the yellowheaded spruce sawfly, Pikonema alaskens is . The percent defoliation of the released trees was six times the defoliation in the control trees. A light overstory for young white spruce is suggested as a silvicultural method of reducing defoliation by this sawfly

    Do We Need to Put God into Emotional Support?: A Comparison of Caucasians’ and African-Americans’ Evaluations of Religious versus Non-Religious Comforting Messages

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    The current study explored whether ethnicity influences young adults’ evaluations of two different sets of comforting messages: those in which concepts such as God, prayer, religion, and faith are woven into low, moderate, and high person-centered strategies (called ‘‘religious strategies’’) and those in which such concepts are not embedded (called ‘‘non-religious strategies’’) into the messages. One hundred ninety-seven college students (63% African-American; 37% Caucasian) rated the sensitivity and effectiveness of religious and non-religious comforting messages. Several significant differences were observed between Caucasians and African-Americans in their evaluations of these strategies. Findings are discussed in terms of their practical implications for ‘‘real world’’ comforting efforts as well as the theoretical significance they hold for the concept of person-centeredness

    Combustion of hydrogen-air jets in local chemical equilibrium: A guide to the CHARNAL computer program

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    A guide to a computer program, written in FORTRAN 4, for predicting the flow properties of turbulent mixing with combustion of a circular jet of hydrogen into a co-flowing stream of air is presented. The program, which is based upon the Imperial College group's PASSA series, solves differential equations for diffusion and dissipation of turbulent kinetic energy and also of the R.M.S. fluctuation of hydrogen concentration. The effective turbulent viscosity for use in the shear stress equation is computed. Chemical equilibrium is assumed throughout the flow

    Shock propagation and stability in causal dissipative hydrodynamics

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    We studied the shock propagation and its stability with the causal dissipative hydrodynamics in 1+1 dimensional systems. We show that the presence of the usual viscosity is not enough to stabilize the solution. This problem is solved by introducing an additional viscosity which is related to the coarse-graining scale of the theory.Comment: 14 pages, 16 figure

    Ion Trap Mass Spectrometers for Identity, Abundance and Behavior of Volatiles on the Moon

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    NASA GSFC and The Open University (UK) are collaborating to deploy an Ion Trap Mass Spectrometer on the Moon to investigate the lunar water cycle. The ITMS is flight-proven throughthe Rosetta Philae comet lander mission. It is also being developed under ESA funding to analyse samples drilled from beneath the lunar surface on the Roscosmos Luna-27 lander (2025).Now, GSFC and OU will now develop a compact ITMS instrument to study the near-surface lunar exosphere on board a CLPS Astrobotic lander at Lacus Mortis in 2021

    Magnetic Helicity in Sphaleron Debris

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    We develop an analytical technique to evaluate the magnetic helicity in the debris from sphaleron decay. We show that baryon number production leads to left-handed magnetic fields, and that the magnetic helicity is conserved at late times. Our analysis explicitly demonstrates the connection between sphaleron-mediated cosmic baryogenesis and cosmic magnetogenesis.Comment: 9 pages, 1 figure. v2: Minor revisions; matches published version in Physical Review

    Anomalous fluctuations of active polar filaments

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    Using a simple model, we study the fluctuating dynamics of inextensible, semiflexible polar filaments interacting with active and directed force generating centres such as molecular motors. Taking into account the fact that the activity occurs on time-scales comparable to the filament relaxation time, we obtain some unexpected differences between both the steady-state and dynamical behaviour of active as compared to passive filaments. For the statics, the filaments have a {novel} length-scale dependent rigidity. Dynamically, we find strongly enhanced anomalous diffusion.Comment: 5 pages, 3 figure

    Screening of charged spheroidal colloidal particles

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    We study the effective screened electrostatic potential created by a spheroidal colloidal particle immersed in an electrolyte, within the mean field approximation, using Poisson--Botzmann equation in its linear and nonlinear forms, and also beyond the mean field by means of Monte Carlo computer simulation. The anisotropic shape of the particle has a strong effect on the screened potential, even at large distances (compared to the Debye length) from it. To quantify this anisotropy effect, we focus our study on the dependence of the potential on the position of the observation point with respect with the orientation of the spheroidal particle. For several different boundary conditions (constant potential, or constant surface charge) we find that, at large distance, the potential is higher in the direction of the large axis of the spheroidal particle

    An exact solution of the moving boundary problem for the expansion of a plasma cylinder in a magnetic field

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    An exact analytic solution has been obtained for a uniformly expanding, neutral, infinitely conducting plasma cylinder in an external uniform and constant magnetic field. The electrodynamical aspects related to the emission and transformation of energy have been considered as well. The results obtained can be used in analysing the recent experimental and simulation data.Comment: 5 pages, 1 figur
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