2,684 research outputs found
Incomplete Delta Functions
By applying projection operators to state vectors of coordinates we obtain
subspaces in which these states are no longer normalized according to Dirac's
delta function but normalized according to what we call "incomplete delta
functions". We show that this class of functions satisfy identities similar to
those satisfied by the Dirac delta function. The incomplete delta functions may
be employed advantageously in projected subspaces and in the link between
functions defined on the whole space and the projected subspace. We apply a
similar procedure to finite dimensional vector spaces for which we define
incomplete Kronecker deltas. Dispersion relations for the momenta are obtained
and ''sums over poles'' are defined and obtained with the aid of differences of
incomplete delta functions.Comment: 11 pages, LaTe
The RR interval spectrum, the ECG signal and aliasing
A reliable spectral analysis requires sampling rate at least twice as large
as the frequency bound, otherwise the analysis will be unreliable and plagued
with aliasing distortions. The RR samplings do not satisfy the above
requirements and therefore their spectral analysis might be unreliable.
In order to demonstrate the feasibility of aliasing in RR spectral analysis,
we have done an experiment which have shown clearly how the aliasing was
developed. In the experiments, one of us (A.G) had kept his high breathing rate
constant with the aid of metronome for more than 5 minutes. The breathing rate
was larger than one-half the heart rate. Very accurate results were obtained
and the resulting aliasing well understood. To our best knowledge this is the
first controlled experiment of this kind coducted on humans.
We compared the RR spectral analysis with the spectrum of the ECG signals
from which the RR intervals were extracted. In the significant for RR analysis
frequencies (below one-half Hertz) significant differences were observed.
In conclusion we recommend to study the spectral analysis of the ECG signal
in the free of aliasing frequency range.Comment: 27 pages, 12 figure
Topology of the Standard Model, I: Fermions
The Harari-Shupe model for fermions is extended to a topological model which
contains an explanation for the observed fact that there are only three
generations of fermions. Topological explanations are given for -decay
and for proton decay predicted in supersymmetry and string theories. An
explanation is given for the observed fact that the three generations of
fermions have such similar properties. The concept of "color" is incorporated
into the model in a topologically meaningful way. Conservation laws are defined
and discussed in the context of the algebraic topology of the model, and preon
number is proved to be linearly determined by charge, weak isospin, and color.Comment: 39 pages, 9 figures. A "disclaimer" has been added at the request of
the editors of the journal to which the article has been submitted for
publication. The new version of 12/26/2015 adds new appendices. One contains
a more intuitive setting meant for those physicists who objected to the van
Kampen diagrams of the original and another contains a geometric model for
quantum entanglemen
Tensor Lagrangians, Lagrangians equivalent to the Hamilton-Jacobi equation and relativistic dynamics
We deal with Lagrangians which are not the standard scalar ones. We present a
short review of tensor Lagrangians, which generate massless free fields and the
Dirac field, as well as vector and pseudovector Lagrangians for the electric
and magnetic fields of Maxwell's equations with sources. We introduce and
analyse Lagrangians which are equivalent to the Hamilton-Jacobi equation and
recast them to relativistic equations.Comment: 12 page
Maxwell equations as the one-photon quantum equation
Maxwell equations (Faraday and Ampere-Maxwell laws) can be presented as a
three component equation in a way similar to the two component neutrino
equation. However, in this case, the electric and magnetic Gauss's laws can not
be derived from first principles. We have shown how all Maxwell equations can
be derived simultaneously from first principles, similar to those which have
been used to derive the Dirac relativistic electron equation. We have also
shown that equations for massless particles, derived by Dirac in 1936, lead to
the same result. The complex wave function, being a linear combination of the
electric and magnetic fields, is a locally measurable and well understood
quantity. Therefore Maxwell equations should be used as a guideline for proper
interpretations of quantum theories.Comment: 9 pages, LaTe
Asphericity for certain groups of cohomological dimension 2
A finite connected 2-complex K whose fundamental group is of cohomological
dimension 2 is aspherical iff the subgroup \Sigma_K of H_2(K) consisting of
spherical 2-cycles is zero. A finite connected subcomplex of an aspherical
2-complex is aspherical iff its fundamental group is of cohomological dimension
2. If G is a countable group such that extension of scalars from Z[G] to
\ell_2(G) kills \bar K_0(Z[G]), and if P is a finitely generated projective
Z[G]-module with P/IP=0, where I is the augmentation ideal of Z[G], then P=0.
In particular, if G is a countable group of cohomological dimension 2 and P is
a finitely generated projective Z[G]-module such that P/IP=0, then P=0.Comment: 11 pages. The new version incorporates results due to B. Eckmann,
fixes an omission, and corrects some typo
Orthogonality and Boundary Conditions in Quantum Mechanics
One-dimensional particle states are constructed according to orthogonality
conditions, without requiring boundary conditions. Free particle states are
constructed using Dirac's delta function orthogonality conditions. The states
(doublets) depend on two quantum numbers: energy and parity. With the aid of
projection operators the particles are confined to a constrained region, in a
way similar to the action of an infinite well potential. From the resulting
overcomplete basis only the mutually orthogonal states are selected. Four
solutions are found, corresponding to different non-commuting Hamiltonians.
Their energy eigenstates are labeled with the main quantum number n and parity
"+" or "-". The energy eigenvalues are functions of n only. The four cases
correspond to different boundary conditions: (I) the wave function vanishes on
the boundary, (II) the derivative of the wavefunction vanishes on the
boundary,(III) periodic (symmetric) boundary conditions, (IV) periodic
(antisymmetric)boundary conditions . Among the four cases, only solution (III)
forms a complete basis in the sense that any function in the constrained
region, can be expanded with it. By extending the boundaries of the constrained
region to infinity, only solution (III) converges uniformly to the free
particle states. Orthogonality seems to be a more basic requirement than
boundary conditions. By using projection operators, confinement of the particle
to a definite region can be achieved in a conceptually simple and unambiguous
way, and physical operators can be written so that they act only in the
confined region.Comment: 10 pages, LaTe
Peculiarities of Brain's Blood Flow : Role of Carbon Dioxide
Among the major factors controlling the cerebral blood flow (CBF), the effect
of PaCO2 is peculiar in that it violates autoregulatory CBF mechanisms and
allows to explore the full range of the CBF. This research resulted in a simple
physical model, with a four parameter formula, relating the CBF to PaCO2. The
parameters can be extracted in an easy manner, directly from the experimental
data. With this model earlier experimental data sets of Rhesus monkeys and rats
were well fitted. Human data were also fitted with this model. Exact formulae
were found, which can be used to transform the fits of one animal to the fits
of another one. The merit of this transformation is that it enable us the use
of rats data as monkeys data simply by rescaling the PaCO2 values and the CBF
data. This transformation makes possible the use of experimental animal data
instead of human ones.Comment: 24 pages, 5 figure
Filling Length in Finitely Presentable Groups
Filling length measures the length of the contracting closed loops in a
null-homotopy. The filling length function of Gromov for a finitely presented
group measures the filling length as a function of length of edge-loops in the
Cayley 2-complex. We give a bound on the filling length function in terms of
the log of an isoperimetric function multiplied by a (simultaneously
realisable) isodiametric function.Comment: 10 pages, 3 figure
Consistent quantization of massless fields of any spin and the generalized Maxwell's equations
A simplified formalism of first quantized massless fields of any spin is
presented. The angular momentum basis for particles of zero mass and finite
spin s of the D^(s-1/2,1/2) representation of the Lorentz group is used to
describe the wavefunctions. The advantage of the formalism is that by equating
to zero the s-1 components of the wave functions, the 2s-1 subsidiary
conditions (needed to eliminate the non-forward and non-backward helicities)
are automatically satisfied. Probability currents and Lagrangians are derived
allowing a first quantized formalism. A simple procedure is derived for
connecting the wave functions with potentials and gauge conditions. The spin 1
case is of particular interest and is described with the D^(1/2,1/2) vector
representation of the well known self-dual representation of the Maxwell's
equations. This representation allows us to generalize Maxwell's equations by
adding the E_0 and B_0 components to the electric and magnetic four-vectors.
Restrictions on their existence are discussed.Comment: IARD 201
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