14,534 research outputs found
From Light Nuclei to Nuclear Matter. The Role of Relativity?
The success of non-relativistic quantum dynamics in accounting for the
binding energies and spectra of light nuclei with masses up to A=10 raises the
question whether the same dynamics applied to infinite nuclear matter agrees
with the empirical saturation properties of large nuclei.The simple unambiguous
relation between few-nucleon and many-nucleon Hamiltonians is directly related
to the Galilean covariance of nonrelativistic dynamics. Relations between the
irreducible unitary representations of the Galilei and Poincare groups indicate
thatthe ``nonrelativistic'' nuclear Hamiltonians may provide sufficiently
accurate approximations to Poincare invariant mass operators. In relativistic
nuclear dynamics based on suitable Lagrangeans the intrinsic nucleon parity is
an explicit, dynamically relevant, degree of freedom and the emphasis is on
properties of nuclear matter. The success of this approach suggests the
question how it might account for the spectral properties of light nuclei.Comment: conference proceedings "The 11th International Conference on Recent
Progress in Many-Body Theories" to be published by World Scientifi
Total scattering descriptions of local and cooperative distortions in the oxide spinel (Mg,Cu)Cr2O4 with dilute Jahn-Teller ions
The normal spinel oxide MgCr2O4 is cubic at room temperature while the normal
spinel CuCr2O4 is tetragonal as a consequence of the Jahn-Teller nature of Cu2+
on the tetrahedral sites. Despite different end-member structures, complete
solid solutions of Mg_{1-x}Cu_xCr2O4 can be prepared that display a first-order
structural transition with composition x = 0.43 at room temperature. Reverse
Monte Carlo analysis of total neutron scattering on data acquired between 300 K
and 15 K on samples with x = 0.10, 0.20, and 0.43 provides unbiased local and
average structure descriptions of the samples, including an understanding of
the transition from local Jahn-Teller distortions in the cubic phase to
cooperative distortions that result in a tetragonal structure. Distributions of
continuous symmetry measures help to understand and distinguish distorted and
undistorted coordination around the tetrahedral site in the solid solutions.
Magnetic exchange bias is observed in field-cooled hysteresis loops of samples
with dilute Cu2+ concentration and in samples with tetragonal--cubic phase
coexistence around 300 K.Comment: 10 pages, 14 figure
A Southern Progressive: M. A. Cassidy and the Lexington Schools, 1886-1928
The 42-year career of M. A. Cassidy exemplifies the transition of public school leadership in Kentucky from non-educators who held religious-political ideologies to professional progressive educators who sought to make Kentucky schools more efficient through expertise and scientific management. This concept was fully adopted in Section 183 of the Kentucky Constitution (1891) which required the General Assembly to âprovide for an efficient system of common schools throughout the state.â
Confident that professional educators were best suited to devise solutions to social problems, and justified by the twin notions of equality of educational opportunity and meritocracy, Cassidy was part of a new breed of progressive educators who joined with the business community to declare that a modest amount of schooling would prepare all for a life of equality, not by restructuring society, but by making each individual better. Cassidy belonged to that class of Southern accommodationist progressive educators who saw themselves as the teachers and guardians of subordinate African Americans in whom they would cultivate âsome measure of collaboration and consent.â
Cassidy presents as a Southern-style reformer working in a border state, but one who held conservative and progressive ideals in equal measure. Like most white Southerners, Cassidy believed that blacks were inherently inferior to whites. But unlike his Southern peers--and despite being part of a community that did not embrace social mobility for blacks--Cassidy was an early adopter of educational equality that included blacks, albeit, in a separate system under Jim Crow. His attention to physical and operational improvements to black schools, including enhanced teacher training and the addition of innovative programs for students, was remarkable for its place and time. But apparent philosophical conflicts fall into place once we see Cassidy for who he was: a public official who necessarily had to work closely with his constituency to achieve his goals; a change agent who used the bully pulpit to extol the virtues of literacy and a proper education; a Christian in the Social Gospel tradition who saw a duty to the least among us; and a personable superintendent who used his sense of Southern gentility to attract more citizens to the enterprise
Superconducting On-chip Fourier Transform Spectrometer
The kinetic inductance effect is strongly nonlinear with applied current in NbTiN, TiN and NbN thin films. This can be utilized to realize novel devices. We present results from transmission lines made with these materials, where DC (current) control is used to modulate the phase velocity thereby enabling on-chip spectrometers. Utility of such compact spectrometers is discussed, along with their natural connection with parametric amplifiers
Technology Development in Water Resource Management
In developed nations, technological advancements rapidlyare changing every aspect of our lives: how we work, howwe communicate with each other, and even how we areentertained. The influence of technology is readilyapparent. The subtleties of technology and its lessapparent influences also are tremendous. Advances incomputer technology, communications, and manufacturingare affecting all sectors, including engineering. In thearena of water resources, technological advances havehelped to not only develop a better understanding of ourphysical systems but have allowed improved operationaland institutional tools to be developed to support watermanagement. These advances have the potential toprovide large and meaningful benefits to less developedinfrastructures.The objective of this paper will be to describe severaltechnological advances in water resources, specifically inareas such as Flood Warning, Water Administration, andMulti-Objective Water Management. Examples oftechnologies implemented which have direct applicabilityto developing infrastructures are described. Important tothe discussion of these advances are the ways in whichimplementation and use of these technologies can protectand save lives, extend and optimally use limited resources,and provide useful inform ation to assist in the sustainab legrowth and development of our natural resources
A Persistent Quandary: The Rural School Improvement Project, 1953-1957
Berea College\u27s Rural School Improvement Project worked directly with more than 5,000 children and 63 teaching fellows in 39 different schools over 13 counties, and one independent school district, involving 10 county school supervisors. Project estimates claimed an indirect impact on approximately 45,000 children within the RSIP school districts. The RSIP represented the thinking of national leaders of rural education in the 1950s who promoted improved administration of the schools combined with an active community engagement program based on âfull respect for human personalityâ and âshared judgments.â Following so many decades of poverty and isolation, it is no easy task to gauge the impact of a program like the Rural School Improvement Project on the children and communities of southeastern Kentucky. Like the progress-minded projects that came before it - and those that would come after - the seemingly intractable challenges attending the Appalachian region kept educational equity at bay. Indeed, it would take another thirty-two years before the landmark Kentucky Supreme Court decision in Rose v Council for Better Education would declare the stateâs inequitable and inadequate school system to be unconstitutional. âSixty-sixâ property poor, and mostly rural, school districts had sued the General Assembly citing the abiding fiscal inequities which had grown to as much as an 8:1 ratio when compared to one urban district. With the passage of the Kentucky Education Reform Act, in 1990, the General Assembly provided substantial funding equity to rural schools - before returning to its historical pattern of periodic attention amid chronic neglect
Attitudes and Preferences of ESL Students to Error Correction
This article presents the findings of a survey of ESL students' attitudes toward and preferences for the correction of spoken errors by native speaker friends. The 418 subjects reported generally positive attitudes toward error correction, and claimed to prefer even more correction than their friends did. They saw correcting errors as facilitating--even being necessary--for the improvement of their oral English
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