Charter School Funding: Inequity in the City

Public charter schools are a growing part of K-12 education. Charter schools are public schools that are granted operational autonomy by their authorizing agency in return for a commitment to achieve specific performance goals. Like traditional public schools, charter schools are free to students and overseen by the state. Unlike traditional public schools, however, most charters are open to all students who wish to apply, regardless of where they live. If a charter school is over-subscribed, usually random lotteries determine which students will be admitted. Most charter schools are independent of the traditional public school district in which they operate

Search for the Tunguska event in the Antarctic snow

The Tunguska explosion in 1908 is supposed to have been produced by the impact of a small celestial body. The absence of any identifiable crater together with the huge energy released by the event suggest that the impactor exploded in midair and that its material was widely spread over the Earth. The short term contribution of such exceptional events to the total accretion rate of extraterrestrial material by the Earth could be significant. Samples were chosen in a core electromechanically drilled in 1984 near South Pole Station. There, the low temperatures, preventing melting all year long, and the nearly regular snow fall rate provide good conditions for a reliable continuous record of any infalling material. In many samples Ir was below the detection limit of the instrumentation. The iridium infall averaged over 45 samples is given. In a few samples the iridium content is significantly higher than the average: the frequency and amplitude of such fluctuations can be explained by the presence on some filters of finite size cosmic particles. No significant systematic increase above the average level is observed in the part of the core corresponding to the Tunguska event. The two major results of this study are: (1) The presence of Tunguska explosion debris in the Antarctic snow is not confirmed; and (2) The estimate of the average iridium infall, is an order of magnitude lower than the Ganapathy's background but is close to the values measured in Antarctic snow and atmospheric samples by Takahashi et al. The results are also consistent with the flux of micrometeoroids deduced from optical and radar observations or derived from the study of Greenland cosmic dust collection but are lower than the flux at mid-latitude measured in paleocene-oligocene sediments from the central part of the Pacific Ocean

Effects of Tetranychus urticae Koch feeding injury on physiological processes in Mentha piperita L.

Studies were conducted to examine the effects of feeding injury by the twospotted spider mite (Tetranychus urticae Koch) on physiological processes of its host plant, peppermint (Mentha piperita L.). Aspects of mite-induced host plant physiological stress that were studied included: 1) effects of injury on plant-water relations; 2) photosynthesis and leaf chlorophyll content; and 3) soluble leaf carbohydrates and starch. The effects of feeding injury are discussed in terms of underlying physiological mechanisms. In addition, new methods for sequential extraction and analysis of peppermint tissues are presented. Development of this methodology was necessary in order to satisfy the special requirements of these studies. The most detrimental effect of feeding injury was damage to leaf epidermis and cuticle and the consequent alteration of plant-water relations. Injured leaves were found to transpire more water at night than did uninjured leaves, resulting in symptoms of plant water stress the following day. These symptoms included reduced leaf water potential (psychrometrically deterimined) and stomatal closure. Levels of soluble peppermint leaf carbohydrates (mainly sucrose, raffinose, and stachyose) were higher on a per leaf basis in mite-injured leaves than in uninjured leaves. It is suggested that an osmotic adjustment mechanism, utilizing soluble carbohydrate as osmoticum, may be operating to maintain turgor in mite injury-induced water-stressed leaves. Stress-induced stomatal closure inhibited photosynthesis, presumably by restricting carbon dioxide exchange. In addition, mite feeding removed significant amounts of leaf chlorophyll, resulting in localized non-photosynthetic, necrotic patches. An injury index based on the number of feeding adult female mites, duration of feeding, and leaf area is presented. This index was used throughout the studies to estimate the relative degree of injury of infested leaves

A Good Investment: The Updated Productivity of Public Charter Schools in Eight U.S. Cities

In 2015-16, the United States spent over $660 billion on its public education system in hopes of providing children with greater opportunities to excel academically and to improve their life trajectories. While public education dollars have risen at a relatively fast pace historically, future challenges, including underfunded pension liabilities, suggest policymakers should economize wherever possible. Meanwhile, the number of public charter schools has increased exponentially. From 1991 to 2018, charter school legislation passed in 44 states and the nation’s capital, and student enrollment in charters increased to around 3.2 million

Prediction Skill of U.S. Flash Droughts in Subseasonal Experiment (SubX) Model Hindcasts

Droughts that establish themselves over a short period of time (weeks to a few months), referred to as flash droughts, can have devastating impacts on agriculture, water resources, and ecosystems. The ability to predict such droughts in advance would greatly enhance our preparation for them and potentially reduce their impacts. The sub-seasonal time scale at which flash droughts occur emphasizes the importance of producing forecasts at weekly or finer intervals that extend beyond the numerical weather prediction time frame. Here we assess the ability of eight global forecast systems, each participating in the Sub-seasonal Experiment project (SubX), to predict key features associated with rapidly developing droughts over the United States during the last two decades. MERRA2 reanalysis is used as observations. Prediction skill for temperature and precipitation anomalies during these events is limited to the first 1-2 weeks after initialization for most hindcasts. However, there are some hindcasts in which large anomalies are well predicted 3-4 weeks or more in advance. The physical mechanisms that are key to the development of surface anomalies, including quasi-stationary atmospheric waves, were also evaluated. Most hindcasts were unable to capture the development or progression of such drought-inducing circulation features more than 1-2 weeks in advance

Charter School Funding: (More) Inequity in the City

Public charter schools are a growing part of K-12 education. Charter schools are public schools that are granted operational autonomy by their authorizing agency in return for a commitment to achieve performance levels specified in a contract. Like traditional public schools, charter schools are prohibited from charging tuition, must not discriminate in admissions or be religious in their operation or affiliation, and are overseen by a public entity. Unlike traditional public schools, however, most charters are open to all students who wish to apply, regardless of where they live. If a charter school is over-subscribed, random lotteries usually determine which students are admitted. Most charter schools are independent of the traditional public school district in which they operate

Bigger Bang, Fewer Bucks? The Productivity of Public Charter Schools in Eight U.S. Cities

School choice skeptics frequently claim that public charter schools perform no better than traditional public schools (TPS) on standardized test scores. Although a few individual studies of public charter schools have supported that claim, the most comprehensive research reports conclude that, though results vary across states and charter school networks, on average public charter schools have a positive effect on student achievement. Charter school performance appears to be especially strong in cities. Moreover, none of the studies of the relative effectiveness of public charter schools have explicitly considered the funding differences that exist across the two public school sectors. All of our research team’s prior reports have found that students in public charter schools receive substantially fewer annual educational resources than their TPS peers. Private philanthropy does not compensate charters for the lack of equity in public funding because TPS receive it, too, and philanthropic dollars compose only 2.5 percent of total charter revenues nationally

Quasi-gaussian fixed points and factorial cumulants in nuclear multifragmentation

We re-analyze the conditions for the phenomenon of intermittency (self-similar fluctuations) to occur in models of multifragmentation. Analyzing two different mechanisms, the bond-percolation and the ERW (Elattari, Richert and Wagner) statistical fragmentation models, we point out a common quasi-gaussian shape of the total multiplicity distribution in the critical range. The fixed-point property is also observed for the multiplicity of the second bin. Fluctuations are studied using scaled factorial cumulants instead of scaled factorial moments. The second-order cumulant displays the intermittency signal while higher order cumulants are equal to zero, revealing a large information redundancy in scaled factorial moments. A practical criterion is proposed to identify the gaussian feature of light-fragment production, distinguishing between a self-similarity mechanism (ERW) and the superposition of independent sources (percolation).Comment: 20 pages, uuencoded .tex file including 16 figure