2,137 research outputs found
The geography of strain: organizational resilience as a function of intergroup relations
Organizational resilience is an organization’s ability to absorb strain and preserve or
improve functioning, despite the presence of adversity. In existing scholarship there is
the implicit assumption that organizations experience and respond holistically to acute
forms of adversity. We challenge this assumption by theorizing about how adversity can
create differential strain, affecting parts of an organization rather than the whole. We
argue that relations among those parts fundamentally shape organizational resilience.
We develop a theoretical model that maps how the differentiated emergence of strain in
focal parts of an organization triggers the movements of adjoining parts to provide or
withhold resources necessary for the focal parts to adapt effectively. Drawing on core
principles of theories about intergroup relations, we theorize about three specific
pathways—integration, disavowal, and reclamation—by which responses of adjoining
parts to focal part strain shape organizational resilience. We further theorize about
influences on whether and when adjoining parts are likely to select different pathways.
The resulting theory reveals how the social processes among parts of organizations
influence member responses to adversity and, ultimately, organizational resilience. We
conclude by noting the implications for organizational resilience theory, research, and
practice.Accepted manuscrip
Pilot interaction with automated airborne decision making systems
The use of advanced software engineering methods (e.g., from artificial intelligence) to aid aircraft crews in procedure selection and execution is investigated. Human problem solving in dynamic environments as effected by the human's level of knowledge of system operations is examined. Progress on the development of full scale simulation facilities is also discussed
Pilot interaction with automated airborne decision making systems
Two project areas were pursued: the intelligent cockpit and human problem solving. The first area involves an investigation of the use of advanced software engineering methods to aid aircraft crews in procedure selection and execution. The second area is focused on human problem solving in dynamic environments, particulary in terms of identification of rule-based models land alternative approaches to training and aiding. Progress in each area is discussed
Development of a rotating gravity gradiometer for earth orbit applications (AAFE)
Some preliminary mission studies are described along with the design, fabrication, and test of a breadboard model of an earth orbital, rotating gravity gradiometer with a design goal of 10 to the minus 11th power/sec sq (0.01 EU) in a 35-sec integration time. The proposed mission uses a Scout vehicle to launch one (or two orthogonally oriented) spin-stabilized satellites into a 330-km circular polar orbit some 20 days before an equinox. During the short orbital lifetime, the experiment would obtain two complete maps of the gravity gradient field with a resolution approaching 270 km (degree 75). The breadboard model of the gradiometer demonstrated a combined thermal and electronic noise threshold of 0.015 EU per data channel. The design changes needed to reduce the noise to less than 0.01 EU were identified. Variations of the sensor output signal with temperature were experimentally determined and a suitable method of temperature compensation was developed and tested. Other possible error sources, such as sensor interaction with satellite dynamics and magnetic fields, were studied analytically and shown to be small
Optimal power generation using dark states in dimers strongly coupled to their environment
Dark state protection has been proposed as a mechanism to increase the power
output of light harvesting devices by reducing the rate of radiative
recombination. Indeed many theoretical studies have reported increased power
outputs in dimer systems which use quantum interference to generate dark
states. These models have typically been restricted to particular geometries
and to weakly coupled vibrational baths. Here we consider the
experimentally-relevant strong vibrational coupling regime with no geometric
restrictions on the dimer. We analyze how dark states can be formed in the
dimer by numerically minimizing the emission rate of the lowest energy excited
eigenstate, and then calculate the power output of the molecules with these
dark states. We find that there are two distinct types of dark states depending
on whether the monomers form homodimers, where energy splittings and dipole
strengths are identical, or heterodimers, where there is some difference.
Homodimers, which exploit destructive quantum interference, produce high power
outputs but strong phonon couplings and perturbations from ideal geometries are
extremely detrimental. Heterodimers, which are closer to the classical picture
of a distinct donor and acceptor molecule, produce an intermediate power output
that is relatively stable to these changes. The strong vibrational couplings
typically found in organic molecules will suppress destructive interference and
thus favour the dark-state enhancement offered by heterodimers.Comment: 20+18 pages, 5+5 figures. We have updated Figures 4, 5, F1 and G1 to
correct for a minor error, however the correction is small and does not
change the message of the paper. We have also added a paragraph to the
appendix to detail how the rotating wave approximation and double excited
state affect the master equatio
Phenology satellite experiment
There are no author-identified significant results in this report
The Positivity of Energy for Asymptotically Anti-de Sitter Spacetimes
We use the formulation of asymptotically anti-de Sitter boundary conditions
given by Ashtekar and Magnon to obtain a coordinate expression for the general
asymptotically AdeS metric in a neighbourhood of infinity. From this, we are
able to compute the time delay of null curves propagating near infinity. If the
gravitational mass is negative, so will be the time delay (relative to null
geodesics at infinity) for certain null geodesics in the spacetime. Following
closely an argument given by Penrose, Sorkin, and Woolgar, who treated the
asymptotically flat case, we are then able to argue that a negative time delay
is inconsistent with non-negative matter-energies in spacetimes having good
causal properties. We thereby obtain a new positive mass theorem for these
spacetimes. The theorem may be applied even when the matter flux near the
boundary-at-infinity falls off so slowly that the mass changes, provided the
theorem is applied in a time-averaged sense. The theorem also applies in
certain spacetimes having local matter-energy that is sometimes negative, as
can be the case in semi-classical gravity.Comment: (Plain TeX - figures not included
Individual Entanglements in a Simulated Polymer Melt
We examine entanglements using monomer contacts between pairs of chains in a
Brownian-dynamics simulation of a polymer melt. A map of contact positions with
respect to the contacting monomer numbers (i,j) shows clustering in small
regions of (i,j) which persists in time, as expected for entanglements. Using
the ``space''-time correlation function of the aforementioned contacts, we show
that a pair of entangled chains exhibits a qualitatively different behavior
than a pair of distant chains when brought together. Quantitatively, about 50%
of the contacts between entangled chains are persistent contacts not present in
independently moving chains. In addition, we account for several observed
scaling properties of the contact correlation function.Comment: latex, 12 pages, 7 figures, postscript file available at
http://arnold.uchicago.edu/~ebn
Scaling dependence on the fluid viscosity ratio in the selective withdrawal transition
In the selective withdrawal experiment fluid is withdrawn through a tube with
its tip suspended a distance S above a two-fluid interface. At sufficiently low
withdrawal rates, Q, the interface forms a steady state hump and only the upper
fluid is withdrawn. When Q is increased (or S decreased), the interface
undergoes a transition so that the lower fluid is entrained with the upper one,
forming a thin steady-state spout. Near this transition the hump curvature
becomes very large and displays power-law scaling behavior. This scaling allows
for steady-state hump profiles at different flow rates and tube heights to be
scaled onto a single similarity profile. I show that the scaling behavior is
independent of the viscosity ratio.Comment: 33 Pages, 61 figures, 1 tabl
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