Improving low-performing schools through external assistance: Lessons from Chicago and California.

This article describes the design and implementation of external support to low-performing schools using data from Chicago and California. Using the literature on external support, instructional capacity, and policy strength, the study gathered data from interviews, observations, document review, and surveys. The findings suggest that the model of assistance employed in both Chicago and California was inadequate to the task. While the policies examined demonstrate recognition that low-performing schools need additional capacity if they are to substantially improve student outcomes, external support providers used limited and haphazard approaches, and as a result, the support component had little influence on teaching and learning. In addition, because the external supports relied on a market-like support structure with few other mechanisms to ensure quality, and because there was limited quantity (intensity) of support, the benefit that external assistance might otherwise have provided was limited. This was particularly problematic for the lowest capacity schools, many of which experienced limited change despite increased educator effort and involvement of external providers. In essence, external assistance through these school accountability policies did little to improve educator and organizational performance

Pecan pest management : insects and diseases (1995)

New June 1995

Evaluation of Stereoscopic Camera Systems for Non-Intrusive Spatial Free Surface Measurement in Coastal Research Laboratories

Physical modelling is instrumental to the progression of coastal engineering research and our understanding of the offshore and nearshore environments. Scaled models are designed and built to be tested in coastal research laboratories, where a wave basin or flume generates the desired wave conditions for experimentation. The surrounding hydrodynamics of the research specimen are measured by deployed wave gauges that collect high-quality water surface elevation data. These instruments are constrained to measuring a single, stationary location and often require arrays of multiple gauges when it is necessary to collect surface elevation data at a high spatial resolution. Hydrodynamic disruption of the support framing and gauges can be significant, and the complete spatial variability in the wave field is still unknown regardless of the array size. When several reflective contours are introduced to a wave system, such as in port basins or with multiple specimen, spatial variability can be amplified and characterizing wave height with a single value is inadequate. The need for a non-intrusive spatial free surface measurement system that is capable of capturing this variability arises. This thesis evaluates two stereoscopic video measurement systems through multiple experiments in the Directional Wave Basin at the O.H. Hinsdale Wave Research Laboratory at Oregon State University. Both systems are tested in a variety of wave conditions and validated using traditional point measurement instruments such as resistive and ultrasonic wave gauges. Their ability to measure a 6 m by 6 m area in the basin is confirmed and further results are discussed. Stereoscopic measurement requires the matching of pixels from multiple calibrated and synchronized video frames through image processing techniques. The positional difference between objects in each frame can then be used to calculate depth and obtain a three-dimensional point cloud of the cameras’ overlapping views. Stereo matching algorithms can have difficulty recognizing smooth, translucent water surfaces, therefore texturization or the addition of seeding material is often required for wave measurement within a laboratory. Seeding can disrupt instrumentation and wave propagation and may not always be feasible for use, so a system capable of non-intrusive free surface measurement was prioritized. Two existing stereo measurement systems were selected for this study: the Wave Acquisition Stereo System (WASS), and the Intel® RealSense™ D455 Depth Camera. WASS is an open-source video post-processing pipeline which utilizes stereo matching algorithms developed for use in the open ocean. Multiple GoPro® camera pairs were calibrated and used for video collection for WASS. The Intel® RealSense™ is a consumer grade active infrared stereo camera that internally processes and displays sensor data in real-time. It is a stand-alone system that provides hardware and software to the user so no additional equipment was needed. Methodologies were developed for both systems’ calibration, data synchronization, and post-processing. The camera positioning, lighting, and wave conditions were optimized in a series of preliminary experiments before each system was thoroughly tested in a variety of regular and irregular waves. It was found that WASS heavily relied on wave breaking for water surface recognition and much of the data associated with unbroken waves was unusable. The Intel® system was capable of reliably capturing the water surface regardless of wave breaking. Both systems could not easily differentiate between objects and the water surface, hence instrumentation in view greatly affected data quality. Both datasets contained high frequency noise, but WASS produced lower quality data than that of the Intel® system. Therefore, the Intel® system’s dataset was selected for a more extensive spatial time and frequency domain analysis. Wave gauges in frame of the camera were used for measurement validation and the average error across all wave cases was 6.81% and 5.21% for mean and significant wave heights respectively. More importantly, the camera successfully captured a high spatial resolution of wave height variability that the array of point gauges were not able to measure. A BDM directionality analysis was completed on both the gauge and Intel® camera measurements to output directional wave spectra, which showed good agreement. Both systems were able to spatially reconstruct the water surface of the basin without the need for seeding material. The Intel® system was easily deployed and more versatile in wave conditions without breaking, but its measurement distance is constrained to the geometries of the sensor housing. The WASS system was more difficult to use but its customizability allowed for hardware selection and the potential to measure a larger water surface area

Synthesis and characterization of Na03RhO206H2O - a semiconductor with a weak ferromagnetic component

We have prepared the oxyhydrate Na03RhO206H2O by extracting Na+ cations from NaRhO2 and intercalating water molecules using an aqueous solution of Na2S2O8. Synchrotron X-ray powder diffraction, thermogravimetric analysis (TGA), and energy-dispersive x-ray analysis (EDX) reveal that a non-stoichiometric Na03(H2O)06 network separates layers of edge-sharing RhO6 octahedra containing Rh3+(4d6, S=0) and Rh4+ (4d5, S=1/2). The resistivities of NaRhO2 and Na03RhO206H2O (T < 300) reveal insulating and semi-conducting behavior with activation gaps of 134 meV and 7.8 meV, respectively. Both Na03RhO206H2O and NaRhO2 show paramagnetism at room temperature, however, the sodium-deficient sample exhibits simultaneously a weak but experimentally reproducible ferromagnetic component. Both samples exhibit a temperature-independent Pauli paramagnetism, for NaRhO2 at T > 50 K and for Na03RhO206H2O at T > 25 K. The relative magnitudes of the temperature-independent magnetic susceptibilities, that of the oxide sample being half that of the oxyhydrate, is consistent with a higher density of thermally accessible electron states at the Fermi level in the hydrated sample. At low temperatures the magnetic moments rise sharply, providing evidence of localized and weakl -ordered electronic spins.Comment: 15 fages 5 figures Solid State Communications in prin

Surface Complexation Model for Strontium Sorption to Amorphous Silica and Goethite

Strontium sorption to amorphous silica and goethite was measured as a function of pH and dissolved strontium and carbonate concentrations at 25 C. Strontium sorption gradually increases from 0 to 100% from pH 6 to 10 for both phases and requires multiple outer-sphere surface complexes to fit the data. All data are modeled using the triple layer model and the site-occupancy standard state; unless stated otherwise all strontium complexes are mononuclear. Strontium sorption to amorphous silica in the presence and absence of dissolved carbonate can be fit with tetradentate Sr{sup 2+} and SrOH{sup +} complexes on the {beta}-plane and a monodentate Sr{sup 2+} complex on the diffuse plane to account for strontium sorption at low ionic strength. Strontium sorption to goethite in the absence of dissolved carbonate can be fit with monodentate and tetradentate SrOH{sup +} complexes and a tetradentate binuclear Sr{sup 2+} species on the {beta}-plane. The binuclear complex is needed to account for enhanced sorption at high strontium surface loadings. In the presence of dissolved carbonate additional monodentate Sr{sup 2+} and SrOH{sup +} carbonate surface complexes on the {beta}-plane are needed to fit strontium sorption to goethite. Modeling strontium sorption as outer-sphere complexes is consistent with quantitative analysis of extended X-ray absorption fine structure (EXAFS) on selected sorption samples that show a single first shell of oxygen atoms around strontium indicating hydrated surface complexes at the amorphous silica and goethite surfaces. Strontium surface complexation equilibrium constants determined in this study combined with other alkaline earth surface complexation constants are used to recalibrate a predictive model based on Born solvation and crystal-chemistry theory. The model is accurate to about 0.7 log K units. More studies are needed to determine the dependence of alkaline earth sorption on ionic strength and dissolved carbonate and sulfate concentrations for the development of a robust surface complexation database to estimate alkaline earth sorption in the environment

Long-term visual outcomes after ruthenium plaque brachytherapy for posterior choroidal melanoma

BACKGROUND: To assess the long-term visual outcomes in patients with posteriorly located choroidal melanoma treated with ruthenium plaque brachytherapy between January 2013 and December 2015. METHODS: A retrospective review was conducted on consecutive patients treated with ruthenium plaque brachytherapy for post-equatorial choroidal melanoma with available Snellen visual acuity before and after treatment, and the development and treatment of radiation complications. RESULTS: There were 219 patients with posterior choroidal melanoma treated with ruthenium plaque brachytherapy. Median follow up was 56.5 months, range 12-81 months. Final visual acuity was ≥6/12 in 97 (44.3%) patients, 6/12 to 6/60 in 57 (26.0%), <6/60 in 55 (25.1%) and 10 (4.6%) eyes were enucleated. Radiation maculopathy was the most common radiation complication encountered, occurring in 53 (24.2%) patients. Of these, final visual acuity was 6/12 in 10 patients (18.9%), 6/12 to 6/60 in 26 (49.1%), <6/60 in 16 (30.2%) and 1 eye (1.9%) was enucleated. Twenty-five (47%) with radiation maculopathy were treated with intravitreal anti-angiogenic therapy, 27 (51%) were monitored and one (2%) was treated with scatter photocoagulation. Eyes treated with intravitreal anti-angiogenic therapy had better final vision than those observed or treated with retinal laser (chi-square, p = 0.04). On multivariate analysis, close proximity to the optic nerve and fovea, and large or notched plaque type was associated with final vision worse than 6/12. CONCLUSION: Most patients treated with ruthenium plaque brachytherapy for posterior choroidal melanoma retain 6/60 vision, with almost half retaining 6/12 vision at long term follow up

Speciation and fate of trace metals in estuarine sediments under reduced and oxidized conditions, Seaplane Lagoon, Alameda Naval Air Station (USA)

We have identified important chemical reactions that control the fate of metal-contaminated estuarine sediments if they are left undisturbed (in situ) or if they are dredged. We combined information on the molecular bonding of metals in solids from X-ray absorption spectroscopy (XAS) with thermodynamic and kinetic driving forces obtained from dissolved metal concentrations to deduce the dominant reactions under reduced and oxidized conditions. We evaluated the in situ geochemistry of metals (cadmium, chromium, iron, lead, manganese and zinc) as a function of sediment depth (to 100 cm) from a 60 year record of contamination at the Alameda Naval Air Station, California. Results from XAS and thermodynamic modeling of porewaters show that cadmium and most of the zinc form stable sulfide phases, and that lead and chromium are associated with stable carbonate, phosphate, phyllosilicate, or oxide minerals. Therefore, there is minimal risk associated with the release of these trace metals from the deeper sediments contaminated prior to the Clean Water Act (1975) as long as reducing conditions are maintained. Increased concentrations of dissolved metals with depth were indicative of the formation of metal HS(- )complexes. The sediments also contain zinc, chromium, and manganese associated with detrital iron-rich phyllosilicates and/or oxides. These phases are recalcitrant at near-neutral pH and do not undergo reductive dissolution within the 60 year depositional history of sediments at this site. The fate of these metals during dredging was evaluated by comparing in situ geochemistry with that of sediments oxidized by seawater in laboratory experiments. Cadmium and zinc pose the greatest hazard from dredging because their sulfides were highly reactive in seawater. However, their dissolved concentrations under oxic conditions were limited eventually by sorption to or co-precipitation with an iron (oxy)hydroxide. About 50% of the reacted CdS and 80% of the reacted ZnS were bonded to an oxide-substrate at the end of the 90-day oxidation experiment. Lead and chromium pose a minimal hazard from dredging because they are bonded to relatively insoluble carbonate, phosphate, phyllosilicate, or oxide minerals that are stable in seawater. These results point out the specific chemical behavior of individual metals in estuarine sediments, and the need for direct confirmation of metal speciation in order to constrain predictive models that realistically assess the fate of metals in urban harbors and coastal sediments

Shadowing in Inelastic Scattering of Muons on Carbon, Calcium and Lead at Low XBj

Nuclear shadowing is observed in the per-nucleon cross-sections of positive muons on carbon, calcium and lead as compared to deuterium. The data were taken by Fermilab experiment E665 using inelastically scattered muons of mean incident momentum 470 GeV/c. Cross-section ratios are presented in the kinematic region 0.0001 < XBj <0.56 and 0.1 < Q**2 < 80 GeVc. The data are consistent with no significant nu or Q**2 dependence at fixed XBj. As XBj decreases, the size of the shadowing effect, as well as its A dependence, are found to approach the corresponding measurements in photoproduction.Comment: 22 pages, incl. 6 figures, to be published in Z. Phys.

Surface complexation model for strontium sorption to amorphous silica and goethite

Strontium sorption to amorphous silica and goethite was measured as a function of pH and dissolved strontium and carbonate concentrations at 25°C. Strontium sorption gradually increases from 0 to 100% from pH 6 to 10 for both phases and requires multiple outer-sphere surface complexes to fit the data. All data are modeled using the triple layer model and the site-occupancy standard state; unless stated otherwise all strontium complexes are mononuclear. Strontium sorption to amorphous silica in the presence and absence of dissolved carbonate can be fit with tetradentate Sr2+ and SrOH+ complexes on the β-plane and a monodentate Sr2+complex on the diffuse plane to account for strontium sorption at low ionic strength. Strontium sorption to goethite in the absence of dissolved carbonate can be fit with monodentate and tetradentate SrOH+ complexes and a tetradentate binuclear Sr2+ species on the β-plane. The binuclear complex is needed to account for enhanced sorption at hgh strontium surface loadings. In the presence of dissolved carbonate additional monodentate Sr2+ and SrOH+ carbonate surface complexes on the β-plane are needed to fit strontium sorption to goethite. Modeling strontium sorption as outer-sphere complexes is consistent with quantitative analysis of extended X-ray absorption fine structure (EXAFS) on selected sorption samples that show a single first shell of oxygen atoms around strontium indicating hydrated surface complexes at the amorphous silica and goethite surfaces

Intrathecal treatment of neoplastic meningitis due to breast cancer with a slow-release formulation of cytarabine

DepoCyte is a slow-release formulation of cytarabine designed for intrathecal administration. The goal of this multi-centre cohort study was to determine the safety and efficacy of DepoCyte for the intrathecal treatment of neoplastic meningitis due to breast cancer. DepoCyte 50 mg was injected once every 2 weeks for one month of induction therapy; responding patients were treated with an additional 3 months of consolidation therapy. All patients had metastatic breast cancer and a positive CSF cytology or neurologic findings characteristic of neoplastic meningitis. The median number of DepoCyte doses was 3, and 85% of patients completed the planned 1 month induction. Median follow up is currently 19 months. The primary endpoint was response, defined as conversion of the CSF cytology from positive to negative at all sites known to be positive, and the absence of neurologic progression at the time the cytologic conversion was documented. The response rate among the 43 evaluable patients was 28% (CI 95%: 14–41%); the intent-to-treat response rate was 21% (CI 95%: 12–34%). Median time to neurologic progression was 49 days (range 1–515(+)); median survival was 88 days (range 1–515(+)), and 1 year survival is projected to be 19%. The major adverse events were headache and arachnoiditis. When drug-related, these were largely of low grade, transient and reversible. Headache occurred on 11% of cycles; 90% were grade 1 or 2. Arachnoiditis occurred on 19% of cycles; 88% were grade 1 or 2. DepoCyte demonstrated activity in neoplastic meningitis due to breast cancer that is comparable to results reported with conventional intrathecal agents. However, this activity was achieved with one fourth as many intrathecal injections as typically required in conventional therapy. The every 2 week dose schedule is a major advantage for both patients and physicians. © 2001 Cancer Research Campaign http://www.bjcancer.co