The Effects of School Integration: Evidence from a Randomized Desegregation Program

This paper studies the impact of a desegregation ruling on several medium-run outcomes. This ruling mandates that seven school districts, which serve higher-income, predominantly-white families, accept a group of minority elementary school students who apply to transfer from a nearby, predominantly-minority school district. Slots are allocated via lottery. The offer to transfer raises college enrollment by 10 percentage points. This is due to greater attendance at two-year colleges and particularly for male students. There is evidence male students are also more likely to vote. In contrast, transferring increases the likelihood of arrest. This is driven by increases in non-violent offenses

Satellite power system: Concept development and evaluation program. Volume 3: Power transmission and reception. Technical summary and assessment

Efforts in the DOE/NASA concept development and evaluation program are discussed for the solar power satellite power transmission and reception system. A technical summary is provided together with a summary of system assessment activities. System options and system definition drivers are described. Major system assessment activities were in support of the reference system definition, solid state system studies, critical technology supporting investigations, and various system and subsystem tradeoffs. These activities are described together with reference system updates and alternative concepts for each of the subsystem areas. Conclusions reached as a result of the numerous analytical and experimental evaluations are presented. Remaining issues for a possible follow-on program are identified

Two-Color Grating Magneto-Optical Trap for Narrow-Line Laser Cooling

We demonstrate the two-color cooling and trapping of alkaline-earth atoms in a grating magneto-optical trap (GMOT). The trap is formed by a single incident laser beam together with four secondary beams that are generated via diffraction from a nanostructured wafer. A grating structure for a GMOT operating with strontium atoms is optimized and fabricated. We trap 10688Sr atoms on the 1S0→1P1 transition at 461nm and transfer 25% of these atoms to the second cooling stage on the narrower 1S0→3P1 intercombination transition at 689nm, preparing a sample of 2.5×105 atoms at 5μK. These results demonstrate the applicability of the GMOT technology in conjunction with two widely differing wavelengths and enable the continued miniaturization of alkaline-earth-based quantum technologies like optical atomic clocks

Leveraging Technology to Engage Parents at Scale: Evidence from a Randomized Controlled Trial

While leveraging parents has the potential to increase student performance, programs that do so are often costly to implement or they target younger children. We partner text-messaging technology with school information systems to automate the gathering and provision of information to parents at scale. In a field experiment across 22 middle and high schools, we used this technology to send automated text-message alerts to parents about their child’s missed assignments, grades and class absences. We pre-specified five primary outcomes. The intervention reduces course failures by 38% and increases class attendance by 17%. Students are more likely to be retained in the district. The positive effects are particularly large for students with below-average GPA and students in high school. There are no effects on standardized test scores however. We randomly chose either the mother or the father to receive the alerts, but there were no differential effects across these subgroups. As in previous research, the intervention appears to change parents’ beliefs about their child’s performance and increases parent monitoring. Our results show that this type of automated technology can improve student effort relatively cheaply and at scale

Application of lower Punch Vibration to improve the mechanical Stability of Tablets

A sufficient mechanical stability of tablets to be compacted prevents problems during tableting (e.g. sticking, capping, lamination) and is crucial with regard to further processing steps such as coating or packaging. Often, an improvement of the mechanical stability is only achievable by an adaption of the production settings (die disk speed) or an alteration of the powder blend composition. In the present study, a novel lower punch vibration device was developed and implemented on a rotary tablet press to improve the mechanical stability of the resulting tablets without changing the production conditions or the powder formulation. Various types of microcrystalline cellulose with different physical properties were selected. The powders were investigated concerning their powder flow, density, particle morphology and surface area and the tablets concerning their weight, tensile strength, and capping index. The results showed that externally applied lower punch vibration improved the mechanical stability of the investigated tablets beyond the adaption of the production settingss and the physical properties of the powder blend

The Effects of Making Performance Information Public: Evidence from Los Angeles Teachers and a Regression Discontinuity Design

In theory, the publication of performance ratings may improve performance through reputation concerns and peer effects or impede performance by demoralizing employees. This paper uses school-district data and a regression discontinuity design to answer how consumers and employees respond to making performance information public. We find that high-performing students sorted into classrooms with highly-rated teachers as a result of publication. Teachers who were published do not perform better or worse than teachers who were not published on average. This average effect is due to the heterogeneous impact of publication; highly-rated teachers perform worse following publication while low-rated teachers perform better. On net, the gap between high and low-performing students closes slightly as a result

Evaluation of the suitability of various lubricants for direct compaction of sorbitol tablet formulations

There is an increasing interest in polyols such as sorbitol in pharmaceutical tablet formulations due to their sweet taste but reduced calorie content and noncariogenic characteristics. Sorbitol is a common tableting excipient and plays a major role in the manufacture of chewable and sublingual tablets. One limitation of sorbitol as tableting excipient is that its hygroscopic nature may cause pronounced friction as well as sticking to the punch surfaces. Therefore, the aim of the present study was to evaluate the suitability of various lubricants for reduction of friction and prevention of sticking during compaction of sorbitol-containing tablets. The efficiency of the most commonly used lubricant magnesium stearate was compared to that of sodium stearyl fumarate (Pruv®), microprilled poloxamer 407 (Lutrol® micro 127) and PEG 4000. Compaction studies were performed using an eccentric tablet press as well as a rotary die tablet press. In addition to the compaction properties, the effect of the investigated lubricants on the tablet properties was evaluated. Considering both the lubricant efficiency and the influence on tablet properties among the investigated lubricants, Pruv® turned out to be most suitable for compaction of the investigated sorbitol tablet formulations. However, the best overall lubricant performance accompanied by excellent tablet properties was observed with a mixture (1:1) of magnesium stearate and Pruv®, indicating a synergistic effect of both lubricants

Modeling meander morphodynamics over self-formed heterogeneous floodplains

This work addresses the signatures embedded in the planform geometry of meandering rivers consequent to the formation of floodplain heterogeneities as the river bends migrate. Two geomorphic features are specifically considered: scroll bars produced by lateral accretion of point bars at convex banks and oxbow lake fills consequent to neck cutoffs. The sedimentary architecture of these geomorphic units depends on the type and amount of sediment, and controls bank erodibility as the river impinges on them, favoring or contrasting the river migration. The geometry of numerically generated planforms obtained for different scenarios of floodplain heterogeneity is compared to that of natural meandering paths. Half meander metrics and spatial distribution of channel curvatures are used to disclose the complexity embedded in meandering geometry. Fourier Analysis, Principal Component Analysis, Singular Spectrum Analysis and Multivariate Singular Spectrum Analysis are used to emphasize the subtle but crucial differences which may emerge between apparently similar configurations. A closer similarity between observed and simulated planforms is attained when fully coupling flow and sediment dynamics (fully-coupled models) and when considering self-formed heterogeneities that are less erodible than the surrounding floodplain

Ultraviolet-B (290 – 320 nm)-Irradiation Inhibits Epidermal Growth-Factor Binding to Mammalian Cells

Mitogens, such as polypeptide growth factors and phorbol ester tumor promoters, act by binding to specific receptors and inducing a pleiotrophic response in cultured mammalian cells, which results in the induction of cellular proliferation. An early effect of such agents is the inhibition of binding of epidermal growth factor (EGF) ot its receptor. Ultravoilet radiation has also been shown to induce a proliferative response in vivo and in vitro and to act as a tumor promoter in animal skin. WE, therefore, examined the effect of ultraviolet radiation (UVB—290–320 nm) on EGF binding to cells in culture. We found that UVB (100–300 J/m2) induced a rapid, dose-dependent inhibition of EGF binding in a mouse fibroblast cell line, which resulted from a decrease in both number and affinity of binding sites. Phosphorylation of the EGF receptor by protein kinase C (PKC) is not likely to be the mechanism for inhibition, since UVB treatment did not result in PKC activation or modulation of phorbol diester binding