323 research outputs found
Making Sense of Family Communication About and at the End of Life: Family Communication Around End-of-Life Planning and Decision Making
Families faced with end-of-life (EOL) decisions on behalf of a family member are charged with honoring a care recipientâs wishes, which may or may not be clear to them. The process of decision making is challenging for surrogate decision makers and their families, and it often results in suboptimal decisions that fail to meet the best interests of the patients, cause stress for family members, and burden the legal and medical systems. Effective family communication, something that legal representatives, medical professionals, and social workers are often in positions to influence, can enhance the quality of EOL care planning and decisions. To this end, we first establish the significance of the family, an interdependent system, for decisions oriented around individual autonomy and independence. We then explore theory and research in family communication that can offer insight into family interaction about EOL preferences and decisions. Communication theory and research provide insight into how individuals and family members communicatively navigate multiple goals in conversations about EOL preferences and manage privacy and disclosure, deal with uncertainty, and negotiate contradictions in the planning and decision-making processes. We advance recommendations for practice associated with each area of research and theory
Instabilities in Josephson Ladders with Current Induced Magnetic Fields
We report on a theoretical analysis, consisting of both numerical and
analytic work, of the stability of synchronization of a ladder array of
Josephson junctions under the influence of current induced magnetic fields.
Surprisingly, we find that as the ratio of the mutual to self inductance of the
cells of the array is increased a region of unstable behavior occurs followed
by reentrant stable synchronization. Analytic work tells us that in order to
understand fully the cause of the observed instabilities the behavior of the
vertical junctions, sometimes ignored in analytic analyses of ladder arrays,
must be taken into account.Comment: RevTeX, 4 pages, 3 figure
Optics-less smart sensors and a possible mechanism of cutaneous vision in nature
Optics-less cutaneous (skin) vision is not rare among living organisms,
though its mechanisms and capabilities have not been thoroughly investigated.
This paper demonstrates, using methods from statistical parameter estimation
theory and numerical simulations, that an array of bare sensors with a natural
cosine-law angular sensitivity arranged on a flat or curved surface has the
ability to perform imaging tasks without any optics at all. The working
principle of this type of optics-less sensor and the model developed here for
determining sensor performance may be used to shed light upon possible
mechanisms and capabilities of cutaneous vision in nature
Multiplet Effects in the Quasiparticle Band Structure of the Anderson Model
In this paper, we examine the mean field electronic structure of the
Anderson lattice model in a slave boson approximation, which should
be useful in understanding the physics of correlated metals with more than one
f electron per site such as uranium-based heavy fermion superconductors. We
find that the multiplet structure of the ion acts to quench the crystal
field splitting in the quasiparticle electronic structure. This is consistent
with experimental observations in such metals as .Comment: 9 pages, revtex, 3 uuencoded postscript figures attached at en
Information and resolution in electromagnetic optical systems
Published versio
Statistical Communication Theory
Contains reports on eleven completed research projects and four on-going research projects.Joint Services Electronics Program (Contract DA36-039-AMC-03200(E))National Science Foundation (Grant GP-2495)National Aeronautics and Space Administration (Grant NsG-334)National Aeronautics and Space Administration (Grant NsG-496
Minimax estimation of the Wigner function in quantum homodyne tomography with ideal detectors
We estimate the quantum state of a light beam from results of quantum
homodyne measurements performed on identically prepared pulses. The state is
represented through the Wigner function, a ``quasi-probability density'' on
which may take negative values and must respect intrinsic
positivity constraints imposed by quantum physics. The data consists of
i.i.d. observations from a probability density equal to the Radon transform of
the Wigner function. We construct an estimator for the Wigner function, and
prove that it is minimax efficient for the pointwise risk over a class of
infinitely differentiable functions. A similar result was previously derived by
Cavalier in the context of positron emission tomography. Our work extends this
result to the space of smooth Wigner functions, which is the relevant parameter
space for quantum homodyne tomography.Comment: 15 page
Statistical Communication Theory
Contains reports on five research projects.National Science Foundation (Grant GP- 2495)National Institutes of Health (Grant MH-04737-05)National Aeronautics and Space Administration (Grant NsG-496
Fisher Information for Inverse Problems and Trace Class Operators
This paper provides a mathematical framework for Fisher information analysis
for inverse problems based on Gaussian noise on infinite-dimensional Hilbert
space. The covariance operator for the Gaussian noise is assumed to be trace
class, and the Jacobian of the forward operator Hilbert-Schmidt. We show that
the appropriate space for defining the Fisher information is given by the
Cameron-Martin space. This is mainly because the range space of the covariance
operator always is strictly smaller than the Hilbert space. For the Fisher
information to be well-defined, it is furthermore required that the range space
of the Jacobian is contained in the Cameron-Martin space. In order for this
condition to hold and for the Fisher information to be trace class, a
sufficient condition is formulated based on the singular values of the Jacobian
as well as of the eigenvalues of the covariance operator, together with some
regularity assumptions regarding their relative rate of convergence. An
explicit example is given regarding an electromagnetic inverse source problem
with "external" spherically isotropic noise, as well as "internal" additive
uncorrelated noise.Comment: Submitted to Journal of Mathematical Physic
Bayesian Bounds on Parameter Estimation Accuracy for Compact Coalescing Binary Gravitational Wave Signals
A global network of laser interferometric gravitational wave detectors is
projected to be in operation by around the turn of the century. Here, the noisy
output of a single instrument is examined. A gravitational wave is assumed to
have been detected in the data and we deal with the subsequent problem of
parameter estimation. Specifically, we investigate theoretical lower bounds on
the minimum mean-square errors associated with measuring the parameters of the
inspiral waveform generated by an orbiting system of neutron stars/black holes.
Three theoretical lower bounds on parameter estimation accuracy are considered:
the Cramer-Rao bound (CRB); the Weiss-Weinstein bound (WWB); and the Ziv-Zakai
bound (ZZB). We obtain the WWB and ZZB for the Newtonian-form of the coalescing
binary waveform, and compare them with published CRB and numerical Monte-Carlo
results. At large SNR, we find that the theoretical bounds are all identical
and are attained by the Monte-Carlo results. As SNR gradually drops below 10,
the WWB and ZZB are both found to provide increasingly tighter lower bounds
than the CRB. However, at these levels of moderate SNR, there is a significant
departure between all the bounds and the numerical Monte-Carlo results.Comment: 17 pages (LaTeX), 4 figures. Submitted to Physical Review
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