2,758 research outputs found
President Clinton Gives ILRF New Grant
This document is part of a digital collection provided by the Martin P. Catherwood Library, ILR School, Cornell University, pertaining to the effects of globalization on the workplace worldwide. Special emphasis is placed on labor rights, working conditions, labor market changes, and union organizing.ILRF_President_Clinton_Gives_ILRF_New_Grant.pdf: 14 downloads, before Oct. 1, 2020
OGO-6 gas-surface energy transfer experiment
The kinetic energy flux of the upper atmosphere was analyzed using OGO-6 data. Energy transfer between 10 microwatts/sq cm and 0.1 W/sq cm was measured by short-term frequency changes of temperature-sensitive quartz crystals used in the energy transfer probe. The condition of the surfaces was continuously monitored by a quartz crystal microbalance to determine the effect surface contamination had on energy accommodation. Results are given on the computer analysis and laboratory tests performed to optimize the operation of the energy transfer probe. Data are also given on the bombardment of OGO-6 surfaces by high energy particles. The thermoelectrically-cooled quartz crystal microbalance is described in terms of its development and applications
Relativistic model of hidden bottom tetraquarks
The relativistic model of the ground state and excited heavy tetraquarks with
hidden bottom is formulated within the diquark-antidiquark picture. The diquark
structure is taken into account by calculating the diquark-gluon vertex in
terms of the diquark wave functions. Predictions for the masses of bottom
counterparts to the charm tetraquark candidates are given.Comment: 6 page
Stable and Reliable Computation of Eigenvectors of Large Profile Matrices
Independent eigenvector computation for a given set of eigenvalues of typical engineering
eigenvalue problems still is a big challenge for established subspace solution methods. The
inverse vector iteration as the standard solution method often is not capable of reliably computing
the eigenvectors of a cluster of bad separated eigenvalues.
The following contribution presents a stable and reliable solution method for independent
and selective eigenvector computation of large symmetric profile matrices. The method
is an extension of the well-known and well-understood QR-method for full matrices thus
having all its good numerical properties. The effects of finite arithmetic precision of
computer representations of eigenvalue/eigenvector solution methods are analysed and it is
shown that the numerical behavior of the new method is superior to subspace solution methods
Are current-induced forces conservative?
The expression for the force on an ion in the presence of current can be
derived from first principles without any assumption about its conservative
character. However, energy functionals have been constructed that indicate that
this force can be written as the derivative of a potential function. On the
other hand, there exist compelling specific arguments that strongly suggest the
contrary. We propose physical mechanisms that invalidate such arguments and
demonstrate their existence with first-principles calculations. While our
results do not constitute a formal resolution to the fundamental question of
whether current-induced forces are conservative, they represent a substantial
step forward in this direction.Comment: 4 pages, 4 Figures, submitted to PR
Flow in a model turbine stator
In view of the complex nature of the flowfield in the hot section of gas turbine engines, the need to predict heat transfer and flow losses, the possible appearance of separation and strong secondary flows, etc., the present effort is focusing upon a Navier-Stokes approach to the three dimensional turbine stator problem. The advantages of a full Navier-Stokes approach are clear since when combined with a suitable turbulence model these equations represent the flow and heat transfer physics. In particular, the Navier-Stokes equations accurately represent possible separated regions and regions of significant secondary flow. In addition, the Navier-Stokes approach allows representation of the entire flow field by a single set of equations, thus avoiding problems associated with representing different regions of the flow by different equations and then matching flow regions
Similar mechanisms of temporary bindings for identity and location of objects in healthy ageing:An eye tracking study with naturalistic scenes
The ability to maintain visual working memory (VWM) associations about the identity and location of objects has at times been found to decrease with age. To date, however, this age-related difficulty was mostly observed in artificial visual contexts (e.g., object arrays), and so it is unclear whether it may manifest in naturalistic contexts, and in which ways. In this eye-tracking study, 26 younger and 24 healthy older adults were asked to detect changes in a critical object situated in a photographic scene (192 in total), about its identity (the object becomes a different object but maintains the same position), location (the object only changes position) or both (the object changes in location and identity). Aging was associated with a lower change detection performance. A change in identity was harder to detect than a location change, and performance was best when both features changed, especially in younger adults. Eye movements displayed minor differences between age groups (e.g., shorter saccades in older adults) but were similarly modulated by the type of change. Latencies to the first fixation were longer and the amplitude of incoming saccades was larger when the critical object changed in location. Once fixated, the target object was inspected for longer when it only changed in identity compared to location. Visually salient objects were fixated earlier, but saliency did not affect any other eye movement measures considered, nor did it interact with the type of change. Our findings suggest that even though aging results in lower performance, it does not selectively disrupt temporary bindings of object identity, location, or their association in VWM, and highlight the importance of using naturalistic contexts to discriminate the cognitive processes that undergo detriment from those that are instead spared by aging
Continuous breakdown of Purcell's scallop theorem with inertia
Purcell's scallop theorem defines the type of motions of a solid body -
reciprocal motions - which cannot propel the body in a viscous fluid with zero
Reynolds number. For example, the flapping of a wing is reciprocal and, as was
recently shown, can lead to directed motion only if its frequency Reynolds
number, Re_f, is above a critical value of order one. Using elementary
examples, we show the existence of oscillatory reciprocal motions which are
effective for all arbitrarily small values of the frequency Reynolds number and
induce net velocities scaling as (Re_f)^\alpha (alpha > 0). This demonstrates a
continuous breakdown of the scallop theorem with inertia.Comment: 6 pages, 1 figur
Stick boundary conditions and rotational velocity auto-correlation functions for colloidal particles in a coarse-grained representation of the solvent
We show how to implement stick boundary conditions for a spherical colloid in
a solvent that is coarse-grained by the method of stochastic rotation dynamics.
This allows us to measure colloidal rotational velocity auto-correlation
functions by direct computer simulation. We find quantitative agreement with
Enskog theory for short times and with hydrodynamic mode-coupling theory for
longer times. For aqueous colloidal suspensions, the Enskog contribution to the
rotational friction is larger than the hydrodynamic one when the colloidal
radius drops below 35nm.Comment: new version with some minor change
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