3,990 research outputs found
Riccati parameter modes from Newtonian free damping motion by supersymmetry
We determine the class of damped modes \tilde{y} which are related to the
common free damping modes y by supersymmetry. They are obtained by employing
the factorization of Newton's differential equation of motion for the free
damped oscillator by means of the general solution of the corresponding Riccati
equation together with Witten's method of constructing the supersymmetric
partner operator. This procedure leads to one-parameter families of (transient)
modes for each of the three types of free damping, corresponding to a
particular type of %time-dependent angular frequency. %time-dependent,
antirestoring acceleration (adding up to the usual Hooke restoring
acceleration) of the form a(t)=\frac{2\gamma ^2}{(\gamma t+1)^{2}}\tilde{y},
where \gamma is the family parameter that has been chosen as the inverse of the
Riccati integration constant. In supersymmetric terms, they represent all those
one Riccati parameter damping modes having the same Newtonian free damping
partner modeComment: 6 pages, twocolumn, 6 figures, only first 3 publishe
Identifying and Defining Natural Service Delivery Systems
One aspect of reality that professional social workers are experiencing in the course of performing social work is what the authors will refer to as natural service delivery systems. We use this particular term for clarity, yet there are questions that still remain. Are there, in fact, measurable phenomena that we can call natural service delivery systems? If these systems exist, what kind of services do they deliver or what types of services do they imply? If these services do exist and if we recognize them, what are the implications for professional social workers? How does our knowledge base allow for us to intervene in these systems with minimal danger of destroying or changing their character and still use them as resources? These questions arose after both authors had worked within communities where, because, of the nature and composition of the populations, it was apparent that natural services were being provided by one neighbor to another or by one friend to another. It was difficult to explain those services in relation to our own roles as social workers. Often it seemed as if there was in existence a procedure that we did not understand in terms of a worker-client relationship. It is from this history of interest and with these questions in mind that we began our research into the area of natural service delivery systems
Quantum Optics
Quantum optics, i.e. the interaction of individual photons with matter, began with the discoveries of Planck and Einstein, but in recent years it has expanded beyond pure physics to become an important driving force for technological innovation. This book serves the broader readership growing out of this development by starting with an elementary description of the underlying physics and then building up a more advanced treatment. The reader is led from the quantum theory of thesimple harmonic oscillator to the application of entangled states to quantum information processing. An equally impo
Numerical Modeling of the Propagation of Infrasonic Acoustic Waves Through the Turbulent Field Generated by the Breaking of Mountain Gravity Waves
The nonlinear propagation of low-frequency acoustic waves through the turbulent fluctuations induced by breaking mountain gravity waves is investigated via 2-D numerical simulations of the Navier-Stokes equations, to understand the effects of atmospheric dynamics on ground-based infrasound measurements. Emphasis is placed on acoustic signals of frequency around 0.1 Hz, traveling through tens-of-kilometers-scale gravity waves and subkilometer-scale turbulence. The sensitivity of the infrasonic phases to small-scale fluctuations is found to depend on the altitudes through which they are refracted toward the Earth. For the considered cases, the dynamics in the stratosphere impact the refracting acoustic waves to a greater extent than those in the thermosphere. This work clearly demonstrates the need for accurate descriptions of the effects of atmospheric dynamics on acoustic propagation, such as here captured by the full set of fluid dynamic equations, as well as of the subsequent effects on measured signals
Telecommunications systems design techniques handbook
Handbook presents design and analysis of tracking, telemetry, and command functions utilized in these systems with particular emphasis on deep-space telecommunications. Antenna requirements are also discussed. Handbook provides number of tables outlining various performance criteria. Block diagrams and performance charts are also presented
Wind-tunnel model study of diffusion: Coalplex Project
July 1975.CER75-76RNM-JEC-JAG3.Includes bibliographical references.Prepared under contract to AE & CI Limited
Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I
We have embarked on a project, under the aegis of the Nearby Stars (NStars)/
Space Interferometry Mission Preparatory Science Program to obtain spectra,
spectral types, and, where feasible, basic physical parameters for the 3600
dwarf and giant stars earlier than M0 within 40 parsecs of the sun. In this
paper we report on the results of this project for the first 664 stars in the
northern hemisphere. These results include precise, homogeneous spectral types,
basic physical parameters (including the effective temperature, surface gravity
and the overall metallicity, [M/H]) and measures of the chromospheric activity
of our program stars. Observed and derived data presented in this paper are
also available on the project's website at http://stellar.phys.appstate.edu/
Canonical and kinetic forms of the electromagnetic momentum in an ad hoc quantization scheme for a dispersive dielectric
An ad hoc quantization scheme for the electromagnetic field in a weakly
dispersive, transparent dielectric leads to the definition of canonical and
kinetic forms for the momentum of the electromagnetic field in a dispersive
medium. The canonical momentum is uniquely defined as the operator that
generates spatial translations in a uniform medium, but the quantization scheme
suggests two possible choices for the kinetic momentum operator, corresponding
to the Abraham or the Minkowski momentum in classical electrodynamics. Another
implication of this procedure is that a wave packet containing a single dressed
photon travels at the group velocity through the medium. The physical
significance of the canonical momentum has already been established by
considerations of energy and momentum conservation in the atomic recoil due to
spontaneous emission, the Cerenkov effect, the Doppler effect, and phase
matching in nonlinear optical processes. In addition, the data of the Jones and
Leslie radiation pressure experiment is consistent with the assignment of one
?k unit of canonical momentum to each dressed photon. By contrast, experiments
in which the dielectric is rigidly accelerated by unbalanced electromagnetic
forces require the use of the Abraham momentum.Comment: 21 pages, 1 figure, aip style, submitted to PR
Critical thinking, cognitive presence, and computer conferencing in distance education
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