Efimov states near a Feshbach resonance and the limits of van der Waals universality at finite background scattering length

We calculate the spectrum of three-body Efimov bound states near a Feshbach resonance within a model which accounts both for the finite range of interactions and the presence of background scattering. The latter may be due to direct interactions in an open channel or a second overlapping Feshbach resonance. It is found that background scattering gives rise to substantial changes in the trimer spectrum as a function of the detuning away from a Feshbach resonance, in particular in the regime where the background channel supports Efimov states on its own. Compared to the situation with negligible background scattering, the regime where van der Waals universality applies is shifted to larger values of the resonance strength if the background scattering length is positive. For negative background scattering lengths, in turn, van der Waals universality extends to even small values of the resonance strength parameter, consistent with experimental results on Efimov states in $^{39}$K. Within a simple model, we show that short-range three-body forces do not affect van der Waals universality significantly. Repulsive three-body forces may, however, explain the observed variation between around $-8$ and $-10$ of the ratio between the scattering length where the first Efimov trimer appears and the van der Waals length.Comment: 17 pages, 13 figures; final version as publishe

The Effect of High Velocity Shear on Coating Properties

The chief reason for this work was to investigate the effect of a high velocity shear imparted to a NoKarb clay by a Cowles Dissolver at 5600 rpm. After 12-hour shearing period drawdowns were made of both the sheared and unsheared clays. Comparisons were then made with respect to brightness, opacity, gloss, Bekk Smoothness, Dennison Wax pick, and K and N Ink Holdout using a starch and a styrene butadiene adhesive

Patterns of Giving in COPPS 2001

Serious researchers of philanthropy have bemoaned the lack of panel datasets for studying giving behavior. That gap is beginning to be filled with the start of the Center on Philanthropy Panel Study (COPPS). COPPS provides the first comprehensive panel study of giving and volunteering in the U.S., and one of the only such studies worldwide to date. Previous U.S. panels studies of giving have employed tax return data, which are limited to gifts of money and property by (in most years) itemizers and include only the financial and limited demographic data reported on those returns

Tracking Giving Across Generations

In an article prepared for New Directions for Philanthropic Fundraising, Richard Steinberg and Mark Wilhelm summarize the type of data collected in COPPS and provide at least four areas of fundraising practice that can be improved with knowledge gained about donors from COPPS: targeting, predicting, benchmarking, and persuasion

Religious and Secular Giving, by Race and Ethnicity

In this article, the authors advance the literature on whether apparent differences in the giving and volunteering of black versus white, or Hispanic versus other families, are real. They employ new data, COPPS, that help to determine whether the differences are due to race and ethnicity themselves or a variety of factors that are correlated with these labels

The Steady Spin

With the object of further clarifying the problem of spinning, the equilibrium of the forces and moments acting on an airplane is discussed in light of the most recent test data. Convinced that in a spin the flight attitude by only small angles of yaw is more or less completely steady, the study is primarily devoted to an investigation of steady spin with no side slip. At small angles, wholly arbitrary and perfectly steady spins may be forced, depending on the type of control displacements. But at large angles only very steep and only "approaching steady" spins are possible, no matter what the control displacements

The dangerous flat spin and the factors affecting it

This report deals first with the fundamental data required for the investigation. These are chiefly the aerodynamic forces and moments acting on an airplane in a flat spin. It is shown that these forces and moments depend principally on the angle of attack and on the rotation about the path axis, and can therefore either be measured in a wind tunnel or calculated from wind-tunnel measurements of lift, drag and moment about the leading edge of the wing of an airplane model at rest. The lift, drag and moments about the span axis are so greatly altered by the rapid rotation in a flat spin, that they can no longer be regarded as independent of rotation. No substantial change in the angles of attack and glide occurring in a flat spin is involved. The cross-wind force, as compared with the lift and drag, can be disregarded in a flat spin

The dangerous sideslip of a stalled airplane and its prevention

This investigation covers only that phase of airplane accidents which are the result of sideslip. We examine the circumstances under which this occurs, study the behavior of present-day airplane types (monoplane, conventional and staggered biplane) therein and endeavor to find a solution whereby this danger may be avoided