208,719 research outputs found
Explicit solutions for relativistic acceleration and rotation
The Lorentz transformations are represented by Einstein velocity addition on
the ball of relativistically admissible velocities. This representation is by
projective maps. The Lie algebra of this representation defines the
relativistic dynamic equation. If we introduce a new dynamic variable, called
symmetric velocity, the above representation becomes a representation by
conformal, instead of projective maps. In this variable, the relativistic
dynamic equation for systems with an invariant plane, becomes a non-linear
analytic equation in one complex variable. We obtain explicit solutions for the
motion of a charge in uniform, mutually perpendicular electric and magnetic
fields. By assuming the Clock Hypothesis and using these solutions, we are able
to describe the space-time transformations between two uniformly accelerated
and rotating systems.Comment: 15 pages 1 figur
A new view on relativity: Part 2. Relativistic dynamics
The Lorentz transformations are represented on the ball of relativistically
admissible velocities by Einstein velocity addition and rotations. This
representation is by projective maps. The relativistic dynamic equation can be
derived by introducing a new principle which is analogous to the Einstein's
Equivalence Principle, but can be applied for any force. By this principle, the
relativistic dynamic equation is defined by an element of the Lie algebra of
the above representation. If we introduce a new dynamic variable, called
symmetric velocity, the above representation becomes a representation by
conformal, instead of projective maps. In this variable, the relativistic
dynamic equation for systems with an invariant plane, becomes a non-linear
analytic equation in one complex variable. We obtain explicit solutions for the
motion of a charge in uniform, mutually perpendicular electric and magnetic
fields. By the above principle, we show that the relativistic dynamic equation
for the four-velocity leads to an analog of the electromagnetic tensor. This
indicates that force in special relativity is described by a differential
two-form
Wildlife and Human Diseases: Symptoms of Endangered Marine Ecosystems & Climate Change
The Center for Health and the Global Environment, Harvard Medical School; Wildlife Trust; the Consortium for Conservation Medicine; and the Environmental and Energy Study Institute hosted a Congressional briefing entitled "Wildlife and Human Diseases: Symptoms of Endangered Marine Ecosystems and Climate Change." The marine coastal environment is being subjected to increased pressure from residential, recreational, and commercial development. The combined effects of spills, leaks and accidents associated with oil extraction and transport further weakens coastal ecosystems leaving them vulnerable to injury. These disturbances, in conjunction with new stresses posed by climate change, is adversely affecting the health of marine life. An increase in disease among marine species raises significant concern on the part of scientists, environmental researchers, and policymakers who believe such events herald heightened risk to wildlife and humans
Neutron skins of Pb and Ca from pionic probes
The neutron skin of Pb has received considerable attention in recent
years. A variety of strongly-interacting probes depict a rather consistent
picture but pionic probes have not been referred to in this context. We present
here neutron-skin values from pionic atoms and from total reaction cross
sections of between 0.7 and 2 GeV/c which fit well into the picture.
In addition we show that a neutron skin for Ca can be obtained from
existing data on pionic atoms and the result agrees with pion scattering
experiments and with the scattering of particles.Comment: 9 pages, 3 figures, to be published in Nuclear Physics
Building the Foundation for Rhode Island Immigrant Assistance Database: A Brief Study of the Communication and Collaboration among Rhode Island Social Service Agencies
The wave-function description of the electromagnetic field
For an arbitrary electromagnetic field, we define a prepotential , which
is a complex-valued function of spacetime. The prepotential is a modification
of the two scalar potential functions introduced by E. T. Whittaker. The
prepotential is Lorentz covariant under a spin half representation. For a
moving charge and any observer, we obtain a complex dimensionless scalar. The
prepotential is a function of this dimensionless scalar. The prepotential
of an arbitrary electromagnetic field is described as an integral over the
charges generating the field. The Faraday vector at each point may be derived
from by a convolution of the differential operator with the alpha matrices
of Dirac. Some explicit examples will be calculated. We also present the
Maxwell equations for the prepotential
Cohomology in Grothendieck Topologies and Lower Bounds in Boolean Complexity
This paper is motivated by questions such as P vs. NP and other questions in
Boolean complexity theory. We describe an approach to attacking such questions
with cohomology, and we show that using Grothendieck topologies and other ideas
from the Grothendieck school gives new hope for such an attack.
We focus on circuit depth complexity, and consider only finite topological
spaces or Grothendieck topologies based on finite categories; as such, we do
not use algebraic geometry or manifolds.
Given two sheaves on a Grothendieck topology, their "cohomological
complexity" is the sum of the dimensions of their Ext groups. We seek to model
the depth complexity of Boolean functions by the cohomological complexity of
sheaves on a Grothendieck topology. We propose that the logical AND of two
Boolean functions will have its corresponding cohomological complexity bounded
in terms of those of the two functions using ``virtual zero extensions.'' We
propose that the logical negation of a function will have its corresponding
cohomological complexity equal to that of the original function using duality
theory. We explain these approaches and show that they are stable under
pullbacks and base change. It is the subject of ongoing work to achieve AND and
negation bounds simultaneously in a way that yields an interesting depth lower
bound.Comment: 70 pages, abstract corrected and modifie
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