Superintendent Evaluation Practices of Building Administrators in Kansas

To what extent is the accountability issue of evaluating building administrators being practical by school superintendents

Transmission, reflection and localization in a random medium with absorption or gain

We study reflection and transmission of waves in a random tight-binding system with absorption or gain for weak disorder, using a scattering matrix formalism. Our aim is to discuss analytically the effects of absorption or gain on the statistics of wave transport. Treating the effects of absorption or gain exactly in the limit of no disorder, allows us to identify short- and long lengths regimes relative to absorption- or gain lengths, where the effects of absorption/gain on statistical properties are essentially different. In the long-lengths regime we find that a weak absorption or a weak gain induce identical statistical corrections in the inverse localization length, but lead to different corrections in the mean reflection coefficient. In contrast, a strong absorption or a strong gain strongly suppress the effect of disorder in identical ways (to leading order), both in the localization length and in the mean reflection coefficient.Comment: Important revisions and expansion caused by a crucial property of $\hat Q

Exact transmission moments in one-dimensional weak localization and single-parameter scaling

We obtain for the first time the expressions for the mean and the variance of the transmission coefficient for an Anderson chain in the weak localization regime, using exact expansions of the complex transmission- and reflection coefficients to fourth order in the weakly disordered site energies. These results confirm the validity of single-parameter scaling theory in a domain where the higher transmission cumulants may be neglected. We compare our results with earlier results for transmission cumulants in the weak localization domain based on the phase randomization hypothesis

Composite Supersymmetries in low-dimensional systems

Starting from a N=1 scalar supermultiplet in 2+1 dimensions, we demonstrate explicitly the appearance of induced N=1 vector and scalar supermultiplets of composite operators made out of the fundamental supersymmetric constituents. We discuss an extension to a N=2 superalgebra with central extension, due to the existence of topological currents in 2+1 dimensions. As a specific model we consider a supersymmetric $CP^1$ $\sigma$-model as the constituent theory, and discuss the relevance of these results for an effective description of the infrared dynamics of planar high-temperature superconducting condensed matter models with quasiparticle excitations near nodal points of their Fermi surface.Comment: 20 pages Latex, no figure

Characterizing liability for cranial nerve injuries: A detailed analysis of 209 malpractice trials

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97521/1/lary23995.pd

General relativistic Sagnac formula revised

The Sagnac effect is a time or phase shift observed between two beams of light traveling in opposite directions in a rotating interferometer. We show that the standard description of this effect within the framework of general relativity misses the effect of deflection of light due to rotational inertial forces. We derive the necessary modification and demonstrate it through a detailed analysis of the square Sagnac interferometer rotating about its symmetry axis in Minkowski space-time. The role of the time shift in a Sagnac interferometer in the synchronization procedure of remote clocks as well as its analogy with the Aharanov-Bohm effect are revised.Comment: 11 pages, 3 figure

Statistical and Dynamical Study of Disease Propagation in a Small World Network

We study numerically statistical properties and dynamical disease propagation using a percolation model on a one dimensional small world network. The parameters chosen correspond to a realistic network of school age children. We found that percolation threshold decreases as a power law as the short cut fluctuations increase. We found also the number of infected sites grows exponentially with time and its rate depends logarithmically on the density of susceptibles. This behavior provides an interesting way to estimate the serology for a given population from the measurement of the disease growing rate during an epidemic phase. We have also examined the case in which the infection probability of nearest neighbors is different from that of short cuts. We found a double diffusion behavior with a slower diffusion between the characteristic times.Comment: 12 pages LaTex, 10 eps figures, Phys.Rev.E Vol. 64, 056115 (2001

Directing human embryonic stem cell differentiation by non-viral delivery of siRNA in 3D culture

Human embryonic stem cells (hESCs) hold great potential as a resource for regenerative medicine. Before achieving therapeutic relevancy, methods must be developed to control stem cell differentiation. It is clear that stem cells can respond to genetic signals, such as those imparted by nucleic acids, to promote lineage-specific differentiation. Here we have developed an efficient system for delivering siRNA to hESCs in a 3D culture matrix using lipid-like materials. We show that non-viral siRNA delivery in a 3D scaffolds can efficiently knockdown 90% of GFP expression in GFP-hESCs. We further show that this system can be used as a platform for directing hESC differentiation. Through siRNA silencing of the KDR receptor gene, we achieve concurrent downregulation (60–90%) in genes representative of the endoderm germ layer and significant upregulation of genes representative of the mesoderm germ layer (27–90 fold). This demonstrates that siRNA can direct stem cell differentiation by blocking genes representative of one germ layer and also provides a particularly powerful means to isolate the endoderm germ layer from the mesoderm and ectoderm. This ability to inhibit endoderm germ layer differentiation could allow for improved control over hESC differentiation to desired cell types.National Institutes of Health (U.S.) (Grant EB000244)National Institutes of Health (U.S.) (Grant DE016561)Alnylam Pharmaceuticals (Firm

To Act and Learn: A Bakhtinian Exploration of Action Learning

This paper considers the work of the Russian social philosopher and cultural theorist, Mikhail Mikhailovich Bakhtin as a source of understanding for those involved in action learning. Drawing upon data gathered over two years during the evaluation of 20 action learning sets in the north of England, we will seek to work with the ideas of Bakhtin to consider their value for those involved in action learning. We consider key Bakhtin features such as Making Meaning, Participative Thinking, Theoreticism and Presence, Others and Outsideness, Voices and Carnival to highlight how Bakhtin's can enhance our understanding of the nature of action and learning

Collective oscillations of a classical gas confined in harmonic traps

Starting from the Boltzmann equation we calculate the frequency and the damping of the monopole and quadrupole oscillations of a classical gas confined in an harmonic potential. The collisional term is treated in the relaxation time approximation and a gaussian ansatz is used for its evaluation. Our approach provides an explicit description of the transition between the hydrodynamic and collisionless regimes in both spherical and deformed traps. The predictions are compared with the results of a numerical simulation.Comment: 6 pages, revtex, 2 figures include