5,279 research outputs found
Adapting a Parenting Skill Program for Blacks In Southern Louisiana: A Sociological Perspective
This paper focuses on the Effective Black Parenting Program developed by the Center for the Improvement of Child Caring. The present inquiry was an attempt to present the adaptation of this program to Black families in a non-urban setting. The author is certified as a facilitator of the program. The study focuses on the use of role analysis and group dynamics as teaching tools. Effective parenting programs are very important in the survival and socialization of Black children
Radiobiological studies of plants orbited in biosatellite 2
Radiation induced mutation rates and cyotlogical changes in plants orbited on Biosatellite
Integrals of motion and the shape of the attractor for the Lorenz model
In this paper, we consider three-dimensional dynamical systems, as for
example the Lorenz model. For these systems, we introduce a method for
obtaining families of two-dimensional surfaces such that trajectories cross
each surface of the family in the same direction. For obtaining these surfaces,
we are guided by the integrals of motion that exist for particular values of
the parameters of the system. Nonetheless families of surfaces are obtained for
arbitrary values of these parameters. Only a bounded region of the phase space
is not filled by these surfaces. The global attractor of the system must be
contained in this region. In this way, we obtain information on the shape and
location of the global attractor. These results are more restrictive than
similar bounds that have been recently found by the method of Lyapunov
functions.Comment: 17 pages,12 figures. PACS numbers : 05.45.+b / 02.30.Hq Accepted for
publication in Physics Letters A. e-mails : [email protected] &
[email protected]
Matrix Quantization of Turbulence
Based on our recent work on Quantum Nambu Mechanics \cite{af2}, we provide
an explicit quantization of the Lorenz chaotic attractor through the
introduction of Non-commutative phase space coordinates as Hermitian matrices in . For the volume preserving part, they satisfy the
commutation relations induced by one of the two Nambu Hamiltonians, the second
one generating a unique time evolution. Dissipation is incorporated quantum
mechanically in a self-consistent way having the correct classical limit
without the introduction of external degrees of freedom. Due to its volume
phase space contraction it violates the quantum commutation relations. We
demonstrate that the Heisenberg-Nambu evolution equations for the Matrix Lorenz
system develop fast decoherence to N independent Lorenz attractors. On the
other hand there is a weak dissipation regime, where the quantum mechanical
properties of the volume preserving non-dissipative sector survive for long
times.Comment: 14 pages, Based on invited talks delivered at: Fifth Aegean Summer
School, "From Gravity to Thermal Gauge theories and the AdS/CFT
Correspondance", September 2009, Milos, Greece; the Intern. Conference on
Dynamics and Complexity, Thessaloniki, Greece, 12 July 2010; Workshop on
"AdS4/CFT3 and the Holographic States of Matter", Galileo Galilei Institute,
Firenze, Italy, 30 October 201
Comparison of X-ray and gamma-ray dose-response curves for pink somatic mutations in Tradescantia clone 02
Microdosimetric data indicate that the mean specific energy,zeta, produced by individual charged particles from X rays and gamma rays is different for the two radiation qualities by nearly a factor of two. In order to test whether this influences the initial, linear component in the dose-effect relations, a comparison was made between dose-response curves for pink somatic mutations inTradescantia clone 02 stamen hairs following X and gamma irradiations. Absorbed doses ranged from 2.66 to 300 rad. The results are in agreement with predictions made on the basis of microdosimetric data. At low doses gamma rays are substantially less effective than X rays. The RBE of gamma rays vs. X rays at low doses was approximately 0.6, a value lower than those usually reported in other experimental systems
Analysis of the Brinkman-Forchheimer equations with slip boundary conditions
In this work, we study the Brinkman-Forchheimer equations driven under slip
boundary conditions of friction type. We prove the existence and uniqueness of
weak solutions by means of regularization combined with the Faedo-Galerkin
approach. Next we discuss the continuity of the solution with respect to
Brinkman's and Forchheimer's coefficients. Finally, we show that the weak
solution of the corresponding stationary problem is stable
On the statistical evaluation of dose-response functions
The linear-quadratic dependence of effect on the dose of ionizing radiation and its biophysical implications are considered. The estimation of the parameters of the response function and the derivation of the joint confidence region of the estimates are described. The method is applied to the induction of pink mutations inTradescantia which follows the linear-quadratic model. The statistical procedure is also suitable for other response functions
In situ measurement of the acoustic performance of a full scale tramway low height noise barrier prototype
International audienceThe performance of a full scale low height barrier prototype meant to attenuate tramway noise is measured in situ. The prototype is made of a simple L-shape assembly of pressed wood boards covered on the source side with fibrous absorbing material, and has been set up temporarily in a residential area in the town of Saint-Martin-d'H` eres, near Grenoble, through which a tramway line passes. A series of pass-by measurements were made at a close receiver location corresponding to the typical height of human ears, with and without the device. The tram speed has been measured as well using an auxiliary microphone located very close to the track. A significant variability in pass-by levels has been found between the different trams, even when applying an approximate correction for speed. However it is shown that the barrier provides on average an attenuation of more than 10 dB(A), during the whole pass-by. Spectral analysis of the recorded signals is carried out as well to estimate the barrier insertion loss more accurately. Furthermore, comparisons between measurements and simplistic BEM calculations show that numerical predictions can yield rather good estimates of the actual in situ performance, within a few dB(A)
Heat Transfer to Longitudinal Laminar Flow Between Cylinders
Consideration is given to the fully developed heat transfer characteristics for longitudinal laminar flow between cylinders arranged in an equilateral triangular array. The analysis is carried out for the condition of uniform heat transfer per unit length. Solutions are obtained for the temperature distribution, and from these, Nusselt numbers are derived for a wide range of spacing-to-diameter ratios. It is found that as the spacing ratio increases, so also does the wall-to-bulk temperature difference for a fixed heat transfer per unit length. Corresponding to a uniform surface temperature around the circumference of a cylinder, the circumferential variation of the local heat flux is computed. For spacing ratios of 1.5 - 2.0 and greater, uniform peripheral wall temperature and uniform peripheral heat flux are simultaneously achieved. A simplified analysis which neglects circumferential variations is also carried out, and the results are compared with those from the more exact formulation
Lorenz-like systems and classical dynamical equations with memory forcing: a new point of view for singling out the origin of chaos
A novel view for the emergence of chaos in Lorenz-like systems is presented.
For such purpose, the Lorenz problem is reformulated in a classical mechanical
form and it turns out to be equivalent to the problem of a damped and forced
one dimensional motion of a particle in a two-well potential, with a forcing
term depending on the ``memory'' of the particle past motion. The dynamics of
the original Lorenz system in the new particle phase space can then be
rewritten in terms of an one-dimensional first-exit-time problem. The emergence
of chaos turns out to be due to the discontinuous solutions of the
transcendental equation ruling the time for the particle to cross the
intermediate potential wall. The whole problem is tackled analytically deriving
a piecewise linearized Lorenz-like system which preserves all the essential
properties of the original model.Comment: 48 pages, 25 figure
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