3,569 research outputs found
The Discrete radon transform: A more efficient approach to image reconstruction
The Radon transform and its inversion are the mathematical keys that enable tomography. Radon transforms are defined for continuous objects with continuous projections at all angles in [0,π). In practice, however, we pre-filter discrete projections take
Gravitation Research
Contains research objectives, summary of research and reports on one research project.National Aeronautics and Space Administration (Grant NGR 22-009-526)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-030
Gravitation Research
Contains research objectives and summary of research.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300National Aeronautics and Space Administration (Grant NGR 22-009-526)National Science Foundation (Grant GP-24254
Fiber-optic three axis magnetometer prototype development
The goal of this research program was to develop a high sensitivity, fiber optic, interferometric, three-axis magnetometer for interplanetary spacecraft applications. Dynamics Technology, Inc. (DTI) has successfully integrated a low noise, high bandwidth interferometer with high sensitivity metallic glass transducers. Also, DTI has developed sophisticated signal processing electronics and complete data acquisition, filtering, and display software. The sensor was packaged in a compact, low power and weight unit which facilitates deployment. The magnetic field sensor had subgamma sensitivity and a dynamic range of 10(exp 5) gamma in a 10 Hz bandwidth. Furthermore, the vector instrument exhibited the lowest noise level when only one axis was in operation. A system noise level of 1 gamma rms was observed in a 1 Hz bandwidth. However, with the other two channels operating, the noise level increased by about one order of magnitude. Higher system noise was attributed to cross-channel interference among the dither fields
The Equivalence of Two Graph Polynomials and a Symmetric Function
The U-polynomial, the polychromate and the symmetric function generalization
of the Tutte polynomial due to Stanley are known to be equivalent in the sense
that the coefficients of any one of them can be obtained as a function of the
coefficients of any other. The definition of each of these functions suggests a
natural way in which to generalize them which also captures Tutte's universal
V-functions as a specialization. We show that the equivalence remains true for
the extended functions thus answering a question raised by Dominic Welsh.Comment: 17 page
Barriers That Influence Adoption of ACL Injury Prevention Programs Among High School Girls’ Soccer Coaches
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Development of Viral Vectors for Use in Cardiovascular Gene Therapy
Cardiovascular disease represents the most common cause of mortality in the developed world but, despite two decades of promising pre-clinical research and numerous clinical trials, cardiovascular gene transfer has so far failed to demonstrate convincing benefits in the clinical setting. In this review we discuss the various targets which may be suitable for cardiovascular gene therapy and the viral vectors which have to date shown the most potential for clinical use. We conclude with a summary of the current state of clinical cardiovascular gene therapy and the key trials which are ongoing
Loss-Induced Limits to Phase Measurement Precision with Maximally Entangled States
The presence of loss limits the precision of an approach to phase measurement
using maximally entangled states, also referred to as NOON states. A
calculation using a simple beam-splitter model of loss shows that, for all
nonzero values L of the loss, phase measurement precision degrades with
increasing number N of entangled photons for N sufficiently large. For L above
a critical value of approximately 0.785, phase measurement precision degrades
with increasing N for all values of N. For L near zero, phase measurement
precision improves with increasing N down to a limiting precision of
approximately 1.018 L radians, attained at N approximately equal to 2.218/L,
and degrades as N increases beyond this value. Phase measurement precision with
multiple measurements and a fixed total number of photons N_T is also examined.
For L above a critical value of approximately 0.586, the ratio of phase
measurement precision attainable with NOON states to that attainable by
conventional methods using unentangled coherent states degrades with increasing
N, the number of entangled photons employed in a single measurement, for all
values of N. For L near zero this ratio is optimized by using approximately
N=1.279/L entangled photons in each measurement, yielding a precision of
approximately 1.340 sqrt(L/N_T) radians.Comment: Additional references include
Gravitation Research
Contains research objectives and summary of research.National Aeronautics and Space Administration (Grant NGR 22-009-526)Joint Services Electronics Program (Contract DAAB07-71-C-0300
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