Review of The Impact of a Universal Class-Size Reduction Policy: Evidence from Florida's Statewide Mandate

A new Think Twice review released today finds that a recent report on the effect of Florida's class-size reduction reform on student achievement does not actually study the impact of class-size reduction.The Impact of a Universal Class-Size Reduction Policy: Evidence from Florida's Statewide Mandate, written by Matthew M. Chingos for the Program on Education Policy and Governance at Harvard University's Kennedy School, was reviewed for the Think Twice think tank review project by Professor Jeremy Finn of the University at Buffalo-SUNY. Finn, a statistics expert, was a lead researcher of Tennessee's Project STAR, a large, randomized experiment in class-size reduction (CSR). In 2002, Florida voters passed a constitutional amendment mandating CSR throughout that state's schools.The Chingos study compares student test scores in districts that already had average class sizes smaller than required by the amendment with student scores in districts with average class sizes larger than required by the amendment. Districts that already had smaller class sizes received the same additional funding but could use the money as they saw fit, while those with larger class sizes were required to use the state CSR funds to reduce class sizes. Chingos concludes that "mandated CSR in Florida had little, if any, effect on cognitive and non-cognitive outcomes" in the students examined. Finn, however, points out that the study doesn't actually address the effect of CSR on student achievement. Instead the study compares the results of schools that reduced class size with a group of schools that received monies to use as they wished. Both sets of districts in the study had small class sizes. According to Finn, the study's finding would more accurately be stated as "administrative discretion in spending state class-size reduction funds did not affect students' academic performance."Finn's review also points out that there are other flaws in the Chingos study: It uses the broad brush of school and district averages rather than student-level information about class sizes and test scores. Also, the actual class-size differences between the two groups were too small to make an educational difference; both of the groups had small average class sizes.Finn concludes, "Despite its title, this report does not address the issue of class-size reduction. By being presented as an evaluation of Florida's mandated class size limits, it may lead parents, educators, or policy makers to draw faulty conclusions about the impact of the program.

Journal of Animal Ethics

A review of Abbey-Anne Smith's book "Animals in Tillich's Philosophical Theology.

The Distribution and Annihilation of Dark Matter Around Black Holes

We use a Monte Carlo code to calculate the geodesic orbits of test particles around Kerr black holes, generating a distribution function of both bound and unbound populations of dark matter particles. From this distribution function, we calculate annihilation rates and observable gamma-ray spectra for a few simple dark matter models. The features of these spectra are sensitive to the black hole spin, observer inclination, and detailed properties of the dark matter annihilation cross section and density profile. Confirming earlier analytic work, we find that for rapidly spinning black holes, the collisional Penrose process can reach efficiencies exceeding $600\%$, leading to a high-energy tail in the annihilation spectrum. The high particle density and large proper volume of the region immediately surrounding the horizon ensures that the observed flux from these extreme events is non-negligible.Comment: accepted to Ap

Electromagnetic Counterparts to Black Hole Mergers

During the final moments of a binary black hole (BH) merger, the gravitational wave (GW) luminosity of the system is greater than the combined electromagnetic output of the entire observable universe. However, the extremely weak coupling between GWs and ordinary matter makes these waves very difficult to detect directly. Fortunately, the inspiraling BH system will interact strongly--on a purely Newtonian level--with any surrounding material in the host galaxy, and this matter can in turn produce unique electromagnetic (EM) signals detectable at Earth. By identifying EM counterparts to GW sources, we will be able to study the host environments of the merging BHs, in turn greatly expanding the scientific yield of a mission like LISA.Comment: 10 pages, 1 figure, submitted to Class. Quantum Grav. special issue: proceedings of 8th LISA Symposiu

Astrophysics of Super-massive Black Hole Mergers

We present here an overview of recent work in the subject of astrophysical manifestations of super-massive black hole (SMBH) mergers. This is a field that has been traditionally driven by theoretical work, but in recent years has also generated a great deal of interest and excitement in the observational astronomy community. In particular, the electromagnetic (EM) counterparts to SMBH mergers provide the means to detect and characterize these highly energetic events at cosmological distances, even in the absence of a space-based gravitational-wave observatory. In addition to providing a mechanism for observing SMBH mergers, EM counterparts also give important information about the environments in which these remarkable events take place, thus teaching us about the mechanisms through which galaxies form and evolve symbiotically with their central black holes.Comment: Invited article for the focus issue on astrophysical black holes in Classical and Quantum Gravity, guest editors: D. Merritt and L. Rezzoll