4,308 research outputs found
Analytic slowing-down distributions as modified by turbulent transport
The effect of electrostatic microturbulence on fast particles rapidly
decreases at high energy, but can be significant at moderate energy. Previous
studies found that, in addition to changes in the energetic particle density,
this results in nontrivial changes to the equilibrium velocity distribution.
These effects have implications for plasma heating and the stability of
Alfv\'en eigenmodes, but make multiscale simulations much more difficult
without further approximations. Here, several related analytic model
distribution functions are derived from first principles with reasonable
approximations. A single dimensionless parameter characterizes the relative
strength of turbulence relative to collisions, and this parameter appears as an
exponent in the model distribution functions. Even the most simple of these
models reproduces key features of the numerical phase-space transport solution
and provides a useful a priori heuristic for determining how strong the effect
of turbulence is on the redistribution of energetic particles in toroidal
plasmas.Comment: 13 pages; 6 figure
Mercerization of Cotton for Strength with Special Reference to Aircraft Cloth
The object of the present investigation was to determine the conditions for mercerizing cotton yarn to obtain the maximum strength for a given weight. Apparatus for controlling the variables was built and yarns were mercerized with it under systematically varied conditions of tension, time, temperature, and concentration of caustic soda. The strongest conclusion to be drawn from this work is that the strongest mercerized yarn of a given count from a given quality of cotton is obtained under the following conditions: 1. use of low-twist yarn obtained with twist multipliers from 2.2 to 3; 2. thorough pretreatment of the yarn to remove all extraneous materials; 3. mercerization at a temperature of 0 C or lower; 4. use of sufficient tension during mercerization to prevent the yarn from contracting more than 3 percent. 5. Use of caustic solution having a concentration of 10 percent or higher; 6. the time of mercerization to be 5 minutes. The resulting yarn should be 40 to 100 percent stronger than the original yarn of the same weight
Locally Polynomially Bounded Structures
We prove a theorem which provides a method for constructing points on
varieties defined by certain smooth functions. We require that the functions
are definable in a definably complete expansion of a real closed field and are
locally definable in a fixed o-minimal and polynomially bounded reduct. As an
application we show that in certain o-minimal structures definable functions
are piecewise implicitly defined over the basic functions in the language.Comment: Change of titl
Sequencing Lifeline Repairs After an Earthquake: An Economic Approach
Recoveries after recent earthquakes in the U.S. and Japan have shown that large welfare gains can be achieved by reshaping current emergency plans as incentive-compatible contracts. We apply tools from the mechanisms design literature to show ways to integrate economic incentives into the management of natural disasters and discuss issues related to the application to seismic event recovery. The focus is on restoring lifeline services such as the water, gas, transportation, and electric power networks. We put forward decisional procedures that an uninformed planner could employ to set repair priorities and help to coordinate lifeline firms in the post-earthquake reconstruction.utilities, inter-temporal decisions, natural disasters, mechanism design, network externalities
Exact norm-conserving stochastic time-dependent Hartree-Fock
We derive an exact single-body decomposition of the time-dependent
Schroedinger equation for N pairwise-interacting fermions. Each fermion obeys a
stochastic time-dependent norm-preserving wave equation. As a first test of the
method we calculate the low energy spectrum of Helium. An extension of the
method to bosons is outlined.Comment: 21 pages, 3 figures, LaTeX fil
A Strategy for the Design of Flame Retardants: Cross-linking Processes
Cross-linking is identified as an effective means for flame retardation of polymers and schemes for the cross-linking of poly(ethylene terephthalate) and poly(methyl methacrylate) are presented. For poly(ethylene terephthalate) the scheme involves polymerization of the initially produced vinyl ester. This is followed by chain-stripping, producing a polyene, and cyclization of this polyene. For poly(methyl methacrylate) the scheme entails the formation of anhydride linkages between adjacent polymer strands. Evidence is presented to show the efficacy of these processes and information is produced to aid in the identification of new flame retardants
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Neural processing of imminent collision in humans
Detecting a looming object and its imminent collision is imperative to survival. For most humans, it is a fundamental aspect of daily activities such as driving, road crossing and participating in sport, yet little is known about how the brain both detects and responds to such stimuli. Here we use functional magnetic resonance imaging to assess neural response to looming stimuli in comparison with receding stimuli and motion-controlled static stimuli. We demonstrate for the first time that, in the human, the superior colliculus and the pulvinar nucleus of the thalamus respond to looming in addition to cortical regions associated with motor preparation. We also implicate the anterior insula in making timing computations for collision events
Implementation of Arbitration Decisions in Domestic Law
Arbitration, even if it seems simply providing for the possibility of arbitration, is increasingly attracting attention as a possible means to discipline the resolution of otherwise potentially intractable international tax controversies concerning the allocation of taxing rights under tax treaties.While perceived, though not without reservation, to be a potential welcome addition to a typical mutual agreement procedure (MAP) patterned on article 25 (“the MAP article”) of the OECD Model Tax Convention on Income and Capital(“the OECD Model”) in the form of article 25(5), other provisions of article 25, notably its “interpretive” and “application,”and “legislative”,aspects and contemplated recourse to a “joint commission”reflect a long-standing awareness, even possibly a latent expectation, that objective interveners and alternative or supplementary means or other extensions of the MAP beyond the typical limits of a “specific case”may help the MAP to achieve its full potential. In fact, one author, in a thoughtful and wide-ranging analysis of arbitration in the tax context, has essentially presumed its usefulness but, in a fashion to which these comments are sensitive, has referred to “mandatory arbitration” as “a solution in search of a problem”.
These comments express a point of view as a contribution to the discussions framed by this book. They proceed on the assumption, for the most part, that an otherwise legally effective arbitration decision can be reached and that what remains is to give it fair effect in relation to states’ assessments of taxpayers under their laws. No assumptions are made about the specific features or peculiarities of particular states’ laws. Ultimately, of course these matter
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