Negotiating the Great Recession: How Teacher Collective Bargaining Outcomes Change in Times of Financial Duress

This article examines how teacher collective bargaining agreements (CBAs), teacher salaries, and class sizes changed during the Great Recession. Using a district-level data set of California teacher CBAs that includes measures of subarea contract strength and salaries from 2005–2006 and 2011–2012 tied to district-level longitudinal data, we estimate difference-in-difference models to examine bargaining outcomes for districts that should have been more or less fiscally constrained. We find that unions and administrators change critical elements of CBAs and district policy during times of fiscal duress. This includes increasing class sizes, reducing instructional time, and lowering base salaries to relieve financial pressures and negotiating increased protections for teachers in areas with less direct financial implications, including grievance procedures and nonteaching duties

The Vergara ruling is a victory for California public school students, but further reforms are still needed to protect students’ rights to a high quality education

Earlier this month, a judge in California ruled that the state’s protections for teachers, including tenure after two years and ‘last in first out’ layoff provisions, violated the state’s constitutional clause guaranteeing a right to equality of education for students. Katharine O. Strunk argues that the state’s policies force districts to retain lower-quality teachers and that the decision is a victory for students and parents in California’s public school system. She writes that if the ruling is upheld, and California’s state legislature is tasked with writing new laws on teacher’s conditions, then they should take lessons from cities such as New York and Washington D.C which have introduced effective reforms to the way that teachers are evaluated and gain tenure

Compreendendo os sinais: São relevantes os modelos de medidas múltiplas da eficácia do professor para fornecer informações consistentes para professores e diretores?

There is increasing policy interest in the use of standards-based multiple measure teacher evaluation systems that include both observational and value-added measures of teacher effectiveness. The growing literature that assesses the relationships between these measures does so mainly in academic settings using a validity lens. While valuable in their own right, this evidence from research-based settings provides little evidence about how teachers and principals receive the different signals from multiple measures of effectiveness when implemented in district contexts. Using pairwise correlations and a series of ordinary least squares regressions, this study assesses the relationships between value-added measures of teacher effectiveness and an observational measure of teacher practice as implemented in a district's pilot of a new standards-based multiple-measure teacher evaluation system. We find moderate correlations between value-added and observation-based measures, indicating that teachers will receive similar but not entirely consistent signals from each performance measure. We conclude by highlighting considerations for districts working to develop and implement standards-based multiple-measure teacher evaluation systems. Cada vez hay más interés en el uso de los sistemas de medidas múltiples de evaluación docente basados en estándares con medidas de observación y de valor añadido de la eficacia docente. La creciente literatura que evalúa las relaciones entre estas medidas lo hace principalmente en el ámbito académico utilizando la lente de la validez. Si bien valiosa, la evidencia basada en la investigación proporciona poca información sobre cómo los profesores y directores reciben las diferentes señales de los múltiples medidas de efectividad cuando se implementa en contextos distritales. Utilizando correlaciones por pares y una serie de regresiones de mínimos cuadrados ordinarios este estudio evalúa la relación entre las medidas de valor agregado de la eficacia docente y una medida observacional de la práctica docente como se aplica en una prueba piloto en un distrito con un sistema de múltiples medidas. Encontramos correlaciones moderadas entre el valor agregado y las medidas basadas en la observación, lo que indica que los docentes recibían señales enteramente coherentes similares pero no de cada medida de desempeño. Concluimos resaltando consideraciones para los distritos que trabajan para desarrollar e implementar sistemas de evaluación docente de medidas múltiples basadas en estándares. Há um crescente interesse em utilizar sistemas de medidas múltiplas de avaliação de professores baseada em padrões, que incluem tanto medidas observacionais e de valor agregado sobre a eficácia do professor. A crescente literatura acadêmica avaliando a relação entre essas medidas usa principalmente o lente de validade. Embora valiosa, as pesquisas baseadas em evidências fornece pouca informação sobre como professores e diretores recebem os diferentes sinais de medidas múltiplas de eficácia quando implementado em contextos distritais. Usando correlações em pares e uma série de regressões este estudo avalia a relação entre as medidas de valor agregado de eficácia do professor e uma medida de observação da prática docente aplicada em um teste piloto em um distrito escolar com um sistema de medidas múltiplas. Foram encontradas correlações moderadas entre as medidas de valor acrescentado baseados na observação, indicando que os professores receberam sinais inteiramente coerentes semelhantes, embora não de cada medida de desempenho. Concluímos, destacando considerações para os distritos que trabalham para desenvolver e implementar sistemas de avaliação de professores com base em padrões de medidas múltiplas.

Magnetic damping of a carbon nanotube NEMS resonator

A suspended, doubly clamped single wall carbon nanotube is characterized at cryogenic temperatures. We observe specific switching effects in dc-current spectroscopy of the embedded quantum dot. These have been identified previously as nano-electromechanical self-excitation of the system, where positive feedback from single electron tunneling drives mechanical motion. A magnetic field suppresses this effect, by providing an additional damping mechanism. This is modeled by eddy current damping, and confirmed by measuring the resonance quality factor of the rf-driven nano-electromechanical resonator in an increasing magnetic field.Comment: 8 pages, 3 figure

Spin-Orbit-Induced Kondo Size Effect in Thin Films with 5/2-spin Impurities

Recently, for spin $S=5/2$ impurities quite different size dependence of the Kondo contribution to the resistivity was found experimentally than for S=2. Therefore previous calculation about the effect of the spin-orbit-induced magnetic anisotropy on the Kondo amplitude of the resistivity is extended to the case of $S=5/2$ impurity spin which differs from the integer spin case as the ground state is degenerated. In this case the Kondo contribution remains finite when the sample size goes to zero and the thickness dependence in the Kondo resistivity is much weaker for Cu(Mn). The behavior of the Kondo coefficient as a function of the thickness depends on the Kondo temperature, that is somewhat stronger for larger $T_K$. Comparing our results with a recent experiment in thin Cu(Mn) films, we find a good agreement.Comment: 8 pages, ReVTeX + 4 figures (Postscript

Emission rate and chemical state estimation by 4-dimensional variational inversion

This study aims to assess the potential and limits of an advanced inversion method to estimate pollutant precursor sources mainly from observations. Ozone, sulphur dioxide, and partly nitrogen oxides observations are taken to infer source strength estimates. As methodology, the four-dimensional variational data assimilation technique has been generalised and employed to include emission rate optimisation, in addition to chemical state estimates as usual objective of data assimilation. To this end, the optimisation space of the variational assimilation system has been complemented by emission rate correction factors of 19 emitted species at each emitting grid point, involving the University of Cologne mesoscale EURAD model. For validation, predictive skills were assessed for an August 1997 ozone episode, comparing forecast performances of pure initial value optimisation, pure emission rate optimisation, and joint emission rate/initial value optimisation. <br><br> Validation procedures rest on both measurements withheld from data assimilation and prediction skill evaluation of forecasts after the inversion procedures. Results show that excellent improvements can be claimed for sulphur dioxide forecasts, after emission rate optimisation. Significant improvements can be claimed for ozone forecasts after initial value and joint emission rate/initial value optimisation of precursor constituents. The additional benefits applying joint emission rate/initial value optimisation are moderate, and very useful in typical cases, where upwind emission rate optimisation is essential. In consequence of the coarse horizontal model grid resolution of 54 km, applied in this study, comparisons indicate that the inversion improvements can rest on assimilating ozone observations only, as the inclusion of NO<sub>x</sub> observations does not provide additional forecast skill. Emission estimates were found to be largely independent from initial guesses from emission inventories, demonstrating the potential of the 4D-var method to infer emission rate improvements. The study also points to the need for improved horizontal model resolution to more efficient use of NO<sub>x</sub> observations

Doppler Shift in Andreev Reflection from a Moving Superconducting Condensate in Nb/InAs Josephson Junctions

We study narrow ballistic Josephson weak links in a InAs quantum wells contacted by Nb electrodes and find a dramatic magnetic-field suppression of the Andreev reflection amplitude, which occurs even for in-plane field orientation with essentially no magnetic flux through the junction. Our observations demonstrate the presence of a Doppler shift in the energy of the Andreev levels, which results from diamagnetic screening currents in the hybrid Nb/InAs-banks. The data for conductance, excess and critical currents can be consistently explained in terms of the sample geometry and the McMillan energy, characterizing the transparency of the Nb/InAs-interface.Comment: 4 pages, 5 figures, title modifie

Aharonov-Bohm differential conductance modulation in defective metallic single-wall carbon nanotubes

Using a perturbative approach, the effects of the energy gap induced by the Aharonov-Bohm (AB) flux on the transport properties of defective metallic single-walled carbon nanotubes (MSWCNTs) are investigated. The electronic waves scattered back and forth by a pair of impurities give rise to Fabry-Perot oscillations which constitutes a coherent backscattering interference pattern (CBSIP). It is shown that, the CBSIP is aperiodically modulated by applying a magnetic field parallel to the nanotube axis. In fact, the AB-flux brings this CBSIP under control by an additional phase shift. As a consequence, the extrema as well as zeros of the CBSIP are located at the irrational fractions of the quantity $\Phi_\rho={\Phi}/{\Phi_0}$, where $\Phi$ is the flux piercing the nanotube cross section and $\Phi_{0}=h/e$ is the magnetic quantum flux. Indeed, the spacing between two adjacent extrema in the magneto-differential conductance (MDC) profile is decreased with increasing the magnetic field. The faster and higher and slower and shorter variations is then obtained by metallic zigzag and armchair nanotubes, respectively. Such results propose that defective metallic nanotubes could be used as magneto-conductance switching devices based on the AB effect.Comment: 11 pages, 4 figure

Co-sputtered MoRe thin films for carbon nanotube growth-compatible superconducting coplanar resonators

Molybdenum rhenium alloy thin films can exhibit superconductivity up to critical temperatures of $T_c=15\mathrm{K}$. At the same time, the films are highly stable in the high-temperature methane / hydrogen atmosphere typically required to grow single wall carbon nanotubes. We characterize molybdenum rhenium alloy films deposited via simultaneous sputtering from two sources, with respect to their composition as function of sputter parameters and their electronic dc as well as GHz properties at low temperature. Specific emphasis is placed on the effect of the carbon nanotube growth conditions on the film. Superconducting coplanar waveguide resonators are defined lithographically; we demonstrate that the resonators remain functional when undergoing nanotube growth conditions, and characterize their properties as function of temperature. This paves the way for ultra-clean nanotube devices grown in situ onto superconducting coplanar waveguide circuit elements.Comment: 8 pages, 6 figure

Balancing Surface Energy Terms for Stable Growth of Planar Surfaces

We investigate the driving forces that determine the growth mode of heteroepitaxial Ge layers grown from solution on Si substrates with orientations (001), (011) and (111) by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Using liquid phase epitaxy, we can study the influences of strain and surface energy terms independently on effects due to limited surface diffusion. In (001) and (011) orientated layers, {111} faceted islands form (Stranski-Krastanov growth). In contrast, (111) orientated layers grow in a two-dimensional step flow growth mode (Frank-van der Merwe growth). We model these investigations in terms of energy minimisation considering surface energy reduction by formation of faceted islands and elastic strain energy relaxation by island formation. The strain energy relaxation by island formation is calculated by the finite element method. According to our considerations, two-dimensional growth is obtained by selective increase of the free surface energy of the low indices facet planes to a value higher than that of the substrate surface. Formation of faceted islands thus would increase the total surface energy; as a consequence, island formation is suppressed. By choosing the appropriate solvent and temperature in solution growth, we can provide for thermodynamically stable two-dimensional growth