The theory and practice of school choice

Education

What Next for School Vouchers?

Voucher, Schule, Schulfinanzierung, Schulpolitik, Bildungsverhalten, Vereinigte Staaten, School, School finance, School policy, Education behaviour, United states

USING MECHANICAL TRADING SYSTEMS TO EVALUATE THE WEAK FORM EFFICIENCY OF FUTURES MARKETS

Research and Development/Tech Change/Emerging Technologies,

WHAT IS "THE BASIS," HOW IS IT MEASURED, AND WHY DOES IT MATTER?

Basis behavior is generally considered to be the major determinant of hedging success or failure. In the course of our work as contract designers for Chicago Mercantile Exchange Inc., we have come to the conclusion that there are many misconceptions and incorrect statements made about "the basis" among practitioners and academics alike. Our work suggests that basis values, how they are measured, what they represent and how they are interpreted may differ widely from one commodity contract to another due to differences in the specifications of the underlying futures market, as well as differences in the structure of the underlying cash market.Marketing,

Devolution\u27s Price

The current political pressures on the welfare state, induced both by fiscal pressures and a Republican majority in Congress, have prompted some of its defenders to look for solutions at state and local levels. They point out that the American federal system is open, complex, and pluralist. Problems that cannot be addressed at one level are often resolved at another. Interests that cannot gain representation in Washington get heard in Albany, Springfield, and Sacramento. They remind us that state and local governments filled in many programmatic gaps opened up by the Reagan Administration. Such optimism, however, is misguided. Current proposals for devolution differ markedly from those of the 1980s. While the Reagan devolution was mainly limited to the developmental or productivity policy arena, the Gingrich devolution promises to shape redistributive policy. This distinction is important because the impact of devolution varies greatly depending on the policy arena in which it occurs

Point-Focus Concentration Compact Telescoping Array: EESP Option 1 Phase Final Report for Public Release

Orbital ATK, in partnership with Mark ONeill LLC (MOLLC) and SolAero Technologies Corp., has developed a novel solar array platform, PFC-CTA, which provides a significant advance in performance and cost reduction compared to all currently available space solar systems. PFC refers to the Point Focus Concentration of light provided by MOLLCs thin, flat Fresnel optics. These lenses focus light to a point of approximately 100 times the intensity of the ambient light, onto a solar cell of approximately 1/25th the size of the lens. CTA stands for Compact Telescoping Array1, which is the solar array blanket structural platform originally devised by NASA and currently being advanced by Orbital ATK and partners under NASA and AFRL funding to a projected TRL 5+ by late-2018. The NASA Game Changing Development Extreme Environment Solar Power (EESP) Option 1 Phase study has enabled Orbital ATK to generate and refine component designs, perform component level and system performance analyses, and test prototype hardware of the key elements of PFC-CTA, and increased the TRL of PFC-specific technology elements to TRL ~5. Key performance metrics currently projected are as follows: Scalability from 300 kW per wing (AM0); Specific Power > 250 W/kg (BoL, AM0); Stowage Efficiency > 60 kW/m3; 5:1 margin on pointing tolerance vs. capability; >50% launched cost savings; Wide range of operability between Venus and Saturn by active and/or passive thermal management

Radio Properties of Low Redshift Broad Line Active Galactic Nuclei

The question as to whether the distribution of radio-loudness in active galactic nuclei (AGN) is actually bimodal has been discussed extensively in the literature. Futhermore, there have been claims that radio-loudness depends on black hole mass and Eddington ratio. We investigate these claims using the low redshift broad line AGN sample of Greene & Ho (2007), which consists of 8434 objects at z < 0.35 from the Sloan Digital Sky Survey Fourth Data Release (SDSS DR4). We obtained radio fluxes from the Very Large Array Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey for the SDSS AGN. Out of the 8434 SDSS AGN, 821 have corresponding observed radio fluxes in the FIRST survey. We calculated the radio-loudness parameter (R) for all objects above the FIRST detection limit (1 mJy), and an upper limit to R for the undetected objects. Using these data, the question of radio bimodality is investigated for different subsets of the total sample. We find no clear demarcation between the radio-loud (RL, R > 10) and radio-quiet (RQ, R < 10) objects, but instead fill in a more radio-intermediate population in a continuous fashion for all subsamples. We find that 4.7% of the AGN in the flux-limited subsample are RL based on core radio emission alone. We calculate the radio-loud fraction (RLF) as both a function of black hole mass and Eddington ratio. The RLF decreases (from 13% to 2%) as Eddington ratio increases over 2.5 order of magnitude. The RLF is nearly constant (~5%) over 4 decades in black hole mass, except for an increase at masses greater than 10^8 solar masses. We find for the FIRST detected subsample that 367 of the RL AGN have black hole masses less than 10^8 solar masses, a large enough number to indicate that RL AGN are not a product of only the most massive black holes in the local universe.Comment: 28 pages, 14 figures, accepted to A

Can Information Widen Socioeconomic Gaps in Postsecondary Aspirations? How College Costs and Returns Affect Parents’ Preferences for Their Children

To estimate whether information can close socioeconomic gaps in parents’ aspirations for their child’s postsecondary education, we administer a four-armed survey experiment to a nationally representative sample of U.S. parents. After respondents estimate costs of and returns to further education, we ask whether they prefer that their child pursue a four-year degree, a two-year degree, or no further education. Before this question is posed, the treated are first told:(1) the net annual costs of pursuing a four-year and two-year degree in their state,(2) the annual returns to four-year and two-year degrees as compared to no further education in their local area, or(3) both costs and returns. We find that information lowers aspirations overall and widens socioeconomic aspiration gaps.These effects do not vary with the magnitude of error between estimated and actual costs and returns. However, we find positive impacts on aspirations among parents who think their child is academically prepared for college

School Vouchers: Settled Questions, Continuing Disputes

Provides an assessment of the constitutional principles announced by the Court, following the June 2002 decision in the Cleveland school voucher case. Presents contrasting arguments on educational policy that address key issues about the decision

Soil Compaction I Where, how bad, a problem

Soil compaction is a more common problem now than it was 15 years ago, regardless of the tillage system used. Producers now use heavier tractors, larger implements, bigger combines, earlier spring tillage, reduced tillage, and no-till planting systems. While all of these have a potential to increase compaction, the major cause of the problem is conducting field operations when the soil is too wet. Most think about tilling wet soils in the spring as being the major problem, but harvesting a too-wet field in the fall can cause just as much compaction. Large combines and auger wagons can have loads exceeding 20 tons per axle. Continuous no-till has also created concerns regarding soil compaction and potential yield decreases. A study in Minnesota that compared no-till and other tillage systems used for 10 years on a clay loam soil showed the greatest soil density for the no-tilled soil. A study in Illinois indicated more compaction with no-till and other reduced tillage systems than with moldboard plow or chisel systems. Generally speaking, no-till is undesirable on a fine textured soil which has poor internal drainage or on a soil that has marginal tilth at the outset. On top of the soils themselves, the residue cover with no-till conserves moisture and slows soil drying, which can further complicate the problems of compaction when no-till is used on poorly drained soils. Soils with good structure, high organic matter, and good internal drainage are less likely to have compaction problems. Also, in low-rainfall areas, such as the Great Plains, compaction is less likely to be a problem than it is in areas of more moisture. The biggest single cause of compaction is the degree of wetness in a field when work is performed in or on that field. Defining compaction Compaction can be defined as the moving of soil particles closer together by external forces exerted by humans, animals, equipment, and/or the impact of water droplets. Packing the soil particles together results in the loss of pore space within the soil. This, in turn, leads to poorer internal drainage and aeration. Under many soil conditions compaction leads to slower water infiltration, which results in greater runoff and soil loss from both rainfall and irrigation. Compaction effects on the crop include reduced plant growth, especially root development, decreased crop yield , and delayed maturity