1,909 research outputs found
Catalysts for polyimide foams from aromatic isocyanates and aromatic dianhydrides
Polyimide foam products having greatly improved burn-through and flame-spread resistance are prepared by the reaction of aromatic polyisocyanates with aromatic dianhydrides in the presence of metallic salts of octoic acid. The salts, for example stannous octoate, ferric octoate and aluminum octoate, favor the formation of imide linkages at the expense of other possible reactions
How stable is the predictive power of the yield curve? Evidence from Germany and the United States
Empirical research over the last decade has uncovered predictive relationships between the slope of the yield curve and subsequent real activity and inflation. Some of these relationships are highly significant, but their theoretical motivations suggest that they may not be stable over time. We use recent econometric techniques for break testing to examine whether the empirical relationships are in fact stable. We consider continuous models, which predict either economic growth or inflation, and binary models, which predict either recessions or inflationary pressure. In each case, we draw on evidence from Germany and the United States. Models that predict real activity are more stable than those that predict inflation, and binary models are more stable than continuous models. The model that predicts recessions is stable over our full sample period in both Germany and the United States
. The Effect of Ethical Leadership on the Work Performance of Employees
The study aimed to determine the effect of ethical leadership on the individual work performance of employees. To deepen the concept of the study and establish theories of the study, literature was reviewed. The study used a descriptive assessment and correlational research design. The population of the study was all the employees of the Divine Word College of Laoag and the data were gathered through research questionnaires. To analyze the data, the weighted mean and Pearson r correlation was used. The results suggest that ethical leadership is significantly correlated with the task performance and counterproductive work behavior and no correlation with the contextual performance
How do Fermi liquids get heavy and die?
We discuss non-Fermi liquid and quantum critical behavior in heavy fermion
materials, focussing on the mechanism by which the electron mass appears to
diverge at the quantum critical point. We ask whether the basic mechanism for
the transformation involves electron diffraction off a quantum critical spin
density wave, or whether a break-down in the composite nature of the heavy
electron takes place at the quantum critical point. We show that the Hall
constant changes continously in the first scenario, but may ``jump''
discontinuously at a quantum critical point where the composite character of
the electron quasiparticles changes.Comment: Revised version with many new references added. To appear as a
topical review in Journal of Physics: Condensed Matter Physics. Two column
version http://www.physics.rutgers.edu/~coleman/online/questions.ps.g
8.2 ka event North Sea hydrography determined by bivalve shell stable isotope geochemistry
This is the final version. Available on open access from Nature Research via the DOI in this recordThe abrupt 8.2 ka cold event has been widely described from Greenland and North Atlantic records. However, its expression in shelf seas is poorly documented, and the temporal resolution of most marine records is inadequate to precisely determine the chronology of major events. A robust hydrographical reconstruction can provide an insight on climatic reaction times to perturbations to the Atlantic Meridional Overturning Circulation. Here we present an annually-resolved temperature and water column stratification reconstruction based on stable isotope geochemistry of Arctica islandica shells from the Fladen Ground (northern North Sea) temporally coherent with Greenland ice core records. Our age model is based on a growth increment chronology obtained from four radiometrically-dated shells covering the 8290–8100 cal BP interval. Our results indicate that a sudden sea level rise (SSLR) event-driven column stratification occurred between ages 8320–8220 cal BP. Thirty years later, cold conditions inhibited water column stratification but an eventual incursion of sub-Arctic waters into the North Sea re-established density-driven stratification. The water temperatures reached their minimum of ~3.7 °C 55 years after the SSLR. Intermittently-mixed conditions were later established when the sub-Arctic waters receded.Natural Environment Research Council (NERC)European Union FP
Simultaneous Embeddings with Few Bends and Crossings
A simultaneous embedding with fixed edges (SEFE) of two planar graphs and
is a pair of plane drawings of and that coincide when restricted to
the common vertices and edges of and . We show that whenever and
admit a SEFE, they also admit a SEFE in which every edge is a polygonal curve
with few bends and every pair of edges has few crossings. Specifically: (1) if
and are trees then one bend per edge and four crossings per edge pair
suffice (and one bend per edge is sometimes necessary), (2) if is a planar
graph and is a tree then six bends per edge and eight crossings per edge
pair suffice, and (3) if and are planar graphs then six bends per edge
and sixteen crossings per edge pair suffice. Our results improve on a paper by
Grilli et al. (GD'14), which proves that nine bends per edge suffice, and on a
paper by Chan et al. (GD'14), which proves that twenty-four crossings per edge
pair suffice.Comment: Full version of the paper "Simultaneous Embeddings with Few Bends and
Crossings" accepted at GD '1
Theories of non-Fermi liquid behavior in heavy fermions
I review our incomplete understanding of non-Fermi liquid behavior in heavy
fermion systems at a quantum critical point. General considerations suggest
that critical antiferromagnetic fluctuations do not destroy the Fermi surface
by scattering the heavy electrons- but by actually breaking up the internal
structure of the heavy fermion. I contrast the weak, and strong-coupling view
of the quantum phase transition, emphasizing puzzles and questions that recent
experiments raise.Comment: Overview talk, SCES Paris 1998. References to Sachdev and Ye adde
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