16,026 research outputs found
Transport coefficients for the shear dynamo problem at small Reynolds numbers
We build on the formulation developed in Sridhar & Singh (JFM, 664, 265,
2010), and present a theory of the \emph{shear dynamo problem} for small
magnetic and fluid Reynolds numbers, but for arbitrary values of the shear
parameter. Specializing to the case of a mean magnetic field that is slowly
varying in time, explicit expressions for the transport coefficients,
and , are derived. We prove that, when the velocity
field is non helical, the transport coefficient vanishes. We then
consider forced, stochastic dynamics for the incompressible velocity field at
low Reynolds number. An exact, explicit solution for the velocity field is
derived, and the velocity spectrum tensor is calculated in terms of the
Galilean--invariant forcing statistics. We consider forcing statistics that is
non helical, isotropic and delta-correlated-in-time, and specialize to the case
when the mean-field is a function only of the spatial coordinate and time
; this reduction is necessary for comparison with the numerical
experiments of Brandenburg, R{\"a}dler, Rheinhardt & K\"apyl\"a (ApJ, 676, 740,
2008). Explicit expressions are derived for all four components of the magnetic
diffusivity tensor, . These are used to prove that the
shear-current effect cannot be responsible for dynamo action at small \re and
\rem, but for all values of the shear parameter.Comment: 27 pages, 5 figures, Published in Physical Review
Electrodynamic Structure of an Outer Gap Accelerator: Location of the Gap and the Gamma-ray Emission from the Crab Pulsar
We investigate a stationary pair production cascade in the outer
magnetosphere of a spinning neutron star. The charge depletion due to global
flows of charged particles, causes a large electric field along the magnetic
field lines. Migratory electrons and/or positrons are accelerated by this field
to radiate curvature gamma-rays, some of which collide with the X-rays to
materialize as pairs in the gap. The replenished charges partially screen the
electric field, which is self-consistently solved together with the
distribution functions of particles and gamma-rays. If no current is injected
at neither of the boundaries of the accelerator, the gap is located around the
conventional null surface, where the local Goldreich-Julian charge density
vanishes. However, we first find that the gap position shifts outwards (or
inwards) when particles are injected at the inner (or outer) boundary. Applying
the theory to the Crab pulsar, we demonstrate that the pulsed TeV flux does not
exceed the observational upper limit for moderate infrared photon density and
that the gap should be located near to or outside of the conventional null
surface so that the observed spectrum of pulsed GeV fluxes may be emitted via a
curvature process. Some implications of the existence of a solution for a super
Goldreich-Julian current are discussed.Comment: 17 pages, 12 figures, submitted to Ap
Defining the Role of Alpha-Macroglobulins in the Pathogenesis of Flavivirus Encephalitis.
M.S. Thesis. University of Hawaiʻi at Mānoa 2018
Family Estate Planning: Revised 1973
This publication discusses why farm and agri-business managers and families should plan their estates and suggests considerations in planning, including titles, transfers, and taxes. Farm examples are used throughout. However, the principles presented apply to many types of family situations. The information is not intended as a substitute for competent advice from an attorney, an insurance estate planning advisor, a bank trust officer, accountant, or other competent estate-planning worker. Rather it raises questions and suggests action that may encourage a family to seek professional help to fulfill its objectives and goals. Estate planning has often been a neglected management activity among rural South Dakotans. When viewed as part of farm and family financial management, it will likely be more interesting to work with. An estate plan involves developing a family\u27s financial, educational, and social goals. It needs to provide a satisfactory income and security. A good plan includes the accumulation and management of real and personal property; selection, and in some cases involvement, of heirs in the estate plan; and provisions for care of minor children. The impact of estate and inheritance taxes should be carefully considered. On estates above certain sizes the federal government levies an estate tax. South Dakota levies an inheritance tax on individuals who receive property from a deceased person. Both taxes are progressive in that the larger the estate and inheritance, the greater the tax rate or percent of an estate that is used to satisfy tax demands. The South Dakota tax rate varies with the degree of relationship of the heirs to the deceased. There are a number of estate planning tools that if properly used can help you obtain your objectives. To clearly understand the tools and the nature of estate planning and to develop your own plan requires a considerable amount of planning time and help. Some tools that you may want to become acquainted with include: wills, property title arrangements, transfer by gifts and sale, trusts, annuities, partnerships and small corporations, life insurance, and the nature of the various taxe
Family Estate Planning: Revised 1967
This publication discusses why farm and agri-business managers and families should plan their estates and suggests considerations in planning, including titles, transfers, and taxes. Farm examples are used throughout. However, the principles presented apply to many types of family situations. The information is not intended as a substitute for competent advice from an attorney, an insurance estate planning advisor, a bank trust officer, accountant, or other competent estate-planning worker. Rather it raises questions and suggests action that may encourage a family to seek professional help to fulfill its objectives and goals. Estate planning has often been a neglected management activity among rural South Dakotans. •when viewed as part of farm and family financial management, it will likely be more interesting to work with. An estate plan involves developing a family\u27s financial, educational, and social goals. It needs to provide a satisfactory income and security. A good plan includes the accumulation and management of real and personal property; selection, and in some cases involvement, of heirs in the estate plan; and provisions for care of minor children. The impact of estate and inheritance taxes should be carefully considered. On estates above certain sizes the federal government levies an estate tax. South Dakota levies an inheritance tax on individuals who receive property from a deceased person. Both taxes are progressive in that the larger the estate and inheritance, the greater the tax rate or percent of an estate that is used to satisfy tax demands. The South Dakota tax rate varies with the degree of relationship of the heirs to the deceased. There are a number of estate planning tools that if properly used can help you obtain your objectives. To clearly understand the tools and the nature of estate planning and to develop your own plan requires a considerable amount of planning time and help. Some tools that you may want to become acquainted with include: wills, property title arrangements, transfer by gifts and sale, trusts, annuities, partnerships and small corporations, life insurance, and the nature of the various taxes
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