61,801 research outputs found
On the stability of solutions of the Lichnerowicz-York equation
We study the stability of solution branches for the Lichnerowicz-York
equation at moment of time symmetry with constant unscaled energy density. We
prove that the weak-field lower branch of solutions is stable whilst the upper
branch of strong-field solutions is unstable. The existence of unstable
solutions is interesting since a theorem by Sattinger proves that the sub-super
solution monotone iteration method only gives stable solutions.Comment: To appear in Classical and Quantum Gravit
Interferometric rotation sensor
Sensor generates interference fringes varying in number (horizontally and vertically) as a function of the total angular deviation relative to the line-of-sight axis. Device eliminates errors from zero or null shift due to lack of electrical circuitry stability
A magnetic stimulation examination of orthographic neighborhood effects in visual word recognition
The split-fovea theory proposes that visual word recognition is mediated by the splitting of the foveal image, with letters to the left of fixation projected to the right hemisphere (RH) and letters to the right of fixation projected to the left hemisphere (LH). We applied repetitive transcranial magnetic stimulation (rTMS) over the left and right occipital cortex during a lexical decision task to investigate the extent to which word recognition processes could be accounted for according to the split-fovea theory. Unilateral rTMS significantly impaired lexical decision latencies to centrally presented words, supporting the suggestion that foveal representation of words is split between the cerebral hemispheres rather than bilateral. Behaviorally, we showed that words that have many orthographic neighbors sharing the same initial letters ("lead neighbors") facilitated lexical decision more than words with few lead neighbors. This effect did not apply to end neighbors (orthographic neighbors sharing the same final letters). Crucially, rTMS over the RH impaired lead-, but not end-neighborhood facilitation. The results support the split-fovea theory, where the RH has primacy in representing lead neighbors of a written word
It's a beautiful thing, the destruction of wor(l)ds
The concept of ‘occupying’ in resistance movements is performative, embodied and affective. It involves ideas and feelings, sounds, smells and words. Thus, this presentation format is that of a dialogue/ performance of collected stories of protesters from Athens and political prisoners. The presenters attempt to resist discursive borders of social science and the arts by occupying both. The stories evoke the urban remapping of a politically charged multitude (in squares and streets) alongside narratives of personal resistance from within institutions (prisons). The common element is a view of resistance as embodied, and with an aim to radically transform the spaces of domination and oppression perceived to be limiting the human rights of the subjects. The data evoke effects/affects of resistance by recalling images (photographs); interview testimonies and narratives of resisting bodies
What is moving in hybrid halide perovskite solar cells?
Organic-inorganic semiconductors, which adopt the perovskite crystal
structure, have perturbed the landscape of contemporary photovoltaics research.
In this Account, we discuss the internal motion of methylammonium lead iodide
(CHNHPbI) and formamidinium lead iodide ([CH(NH)]PbI),
covering: (i) molecular rotation-libration in the cuboctahedral cavity; (ii)
drift and diffusion of large electron and hole polarons; (iii) transport of
charged ionic defects. These processes give rise to a range of properties that
are unconventional for photovoltaic materials, including frequency-dependent
permittivity, low electron-hole recombination rates, and current-voltage
hysteresis. Multi-scale simulations - drawing from electronic structure, ab
initio molecular dynamic and Monte Carlo techniques - have been combined with
neutron scattering and ultra-fast vibrational spectroscopy to qualify the
nature and timescales of the motions. Recent experimental evidence and
theoretical models for simultaneous electron transport and ion transport in
these materials has been presented, suggesting they are mixed-mode conductors
with similarities to metal oxide perovskites developed for battery and fuel
cell applications. We expound on the implications of these effects for the
photovoltaic action. The temporal behaviour found in hybrid perovskites
introduces a sensitivity in materials characterisation to the time and length
scale of the measurement, as well as the history of each sample. It also poses
significant challenges for accurate materials and device simulations. Herein,
we critically discuss the atomistic origin of the dynamic processes.Comment: 29 pages, 3 figure
Economics of Change in Market Structure, Conduct, and Performance The Baking Industry 1947-1958
Baking is one of the largest industries in the United States. Its sales, which exceed 1 out of every $10 spent by American consumers for food. Almost half of the domestic consumption of wheat flour is in the form of bread, rolls, cake, pie, doughnuts, sweet goods, and other perishable bakery products. While this study encompasses the perishable bakery products industry as defined by the U.S. Census Bureau, it focuses primarily on wholesale markets for white bread.
Since World War II, important changes have occurred in the bread baking industry. A decline in the per capita demand for bread products coupled with changes in technology and costs has affected the relationships between baking companies, their market behavior, and the resulting level of efficiency and price performance. In an industrial economy, the farming, milling, baking, retailing, and consuming functions are integrally related. Changes in the organization and practices in one may induce changes in others. The baking industry occupies a strategic position in this process, and as a result, consumers, farmers, millers, and retailers, as well as bakers themselves, have a vital interest in the way the baking industry performs.
Changes in market structure and firm behavior in the baking industry have been the subject of study and concern by several interested individuals and groups. The U.S. Department of Agriculture has followed with increased concern the widening of the market margin and the declining farmer share of consumer bread prices. The Senate Agricultural Committee has completed a study of average cost and returns of bakery operations.The Federal Trade Commission has followed the pricing practices of many baking companies with frequent cease and desist orders. I\u3e The Justice Department, through periodic prosecutions, has kept baking firms aware of the limitation imposed by the antitrust laws. The Senate Subcommittee on Antitrust and Monopoly has studied the impact of discriminatory pricing by large baking companies on small independent bakers.7 The industry has encouraged economic study of the historic development of baking and changes in market organization and practices.s Most recently, the F.T.C. studied buyer concentration and the integration of retail grocery organizations into baking and other food processing industries
Pragmatism and Conscience: A Religious Perspective on Competing Values in Embryo Experimentation
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