Predicting Success, Preventing Failure: An Investigation of the California High School Exit Exam

Examines early indicators that identify fourth-grade students in San Diego who are at risk of failing the California High School Exit Exam, discusses implications for when and how to intervene to address those factors, and makes policy recommendations

Lessons in Reading Reform: Finding What Works

Evaluates elements of reforms designed to improve reading scores among students identified as lagging behind, including extended-length English classes and school years. Considers the role of teachers' experience, lessons learned, and policy implications

Discovery of a Low-mass Companion to a Metal-rich F Star with the MARVELS Pilot Project

We report the discovery of a low-mass companion orbiting the metal-rich, main sequence F star TYC 2949-00557-1 during the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) pilot project. The host star has an effective temperature T_(eff) = 6135 ± 40 K, logg = 4.4 ± 0.1, and [Fe/H] = 0.32 ± 0.01, indicating a mass of M_⊙ = 1.25 ± 0.09 M_⊙ and R = 1.15 ± 0.15 R_⊙. The companion has an orbital period of 5.69449 ± 0.00023 days and straddles the hydrogen burning limit with a minimum mass of 64 M_J , and thus may be an example of the rare class of brown dwarfs orbiting at distances comparable to those of "Hot Jupiters." We present relative photometry that demonstrates that the host star is photometrically stable at the few millimagnitude level on time scales of hours to years, and rules out transits for a companion of radius ≳ 0.8 R_J at the 95% confidence level. Tidal analysis of the system suggests that the star and companion are likely in a double synchronous state where both rotational and orbital synchronization have been achieved. This is the first low-mass companion detected with a multi-object, dispersed, fixed-delay interferometer

Passing the California High School Exit Exam: Have Recent Policies Improved Student Performance?

This report evaluates the effectiveness of three support services in helping struggling students pass the California High School Exit Examination (CAHSEE). The report highlights the need to help students before they first take the exam in grade 10 and introduces the CAHSEE Early Warning Model, a forecasting tool to identify at-risk students in earlier grades

Detailed Topography of the Fermi Surface of Sr2RuO4

We apply a novel analysis of the field and angle dependence of the quantum-oscillatory amplitudes in the unconventional superconductor Sr2RuO4 to map its Fermi surface in unprecedented detail, and to obtain previously inaccessible information on the band dispersion. The three quasi-2D Fermi surface sheets not only exhibit very diverse magnitudes of warping, but also entirely different dominant warping symmetries. We use the data to reassess recent results on c-axis transport phenomena.Comment: REVTeX, 4 page

Effect of magnetic fluctuations on the normal state properties of Sr_2RuO_4

We investigate the normal state transport properties of Sr$_2$RuO$_4$ and we show that a consistent explanation of the experimental results can be obtained assuming that the system is near a quantum phase transition. Within the framework of a self-consistent spin fluctuation theory, we calculate the temperature variation of some relevant physical quantities and we discuss a possible microscopic origin of the quantum phase transition.Comment: 5 pages, 4 figures, to appear on Europhysics Letter

Costly Offers and the Equilibration Properties of the Multiple Unit Double Auction Under Conditions of Unpredictable Shifts of Demand and Supply

The paper reports on the behavior of markets in which a transactions cost is imposed in the form of a tax on bids and asks that are tendered in the market. That is, in the markets studied communication with the other side of the market was costly. The markets were nonstationary in the sense that market demand and market supply shifted unpredictably each period and the markets were organized by the computerized Multiple Unit Double Auction. The results are as follow. (1) A market equilibration process is observed across the periods of nonstationary markets. (2) The imposition of the cost on offers did not negate the tendency toward market equilibration but the price discovery process was "incomplete" relative to the free offer case. (3) Price equilibration with the offer cost was slower and efficiencies were reduced

High Resolution Simulations of the Plunging Region in a Pseudo-Newtonian Potential: Dependence on Numerical Resolution and Field Topology

New three dimensional magnetohydrodynamic simulations of accretion disk dynamics in a pseudo-Newtonian Paczynski-Wiita potential are presented. These have finer resolution in the inner disk than any previously reported. Finer resolution leads to increased magnetic field strength, greater accretion rate, and greater fluctuations in the accretion rate. One simulation begins with a purely poloidal magnetic field, the other with a purely toroidal field. Compared to the poloidal initial field simulation, a purely toroidal initial field takes longer to reach saturation of the magnetorotational instability and produces less turbulence and weaker magnetic field energies. For both initial field configurations, magnetic stresses continue across the marginally stable orbit; measured in units corresponding to the Shakura-Sunyaev alpha parameter, the stress grows from ~0.1 in the disk body to as much as ~10 deep in the plunging region. Matter passing the inner boundary of the simulation has ~10% greater binding energy and ~10% smaller angular momentum than it did at the marginally stable orbit. Both the mass accretion rate and the integrated stress fluctuate widely on a broad range of timescales.Comment: Accepted for publication in the Astrophysical Journal. For Web version with mpeg animations see http://www.astro.virginia.edu/VITA/papers/plunge