Building a Grad Nation: Progress and Challenge in Ending the High School Dropout Epidemic

This fourth annual update on America's high school dropout crisis shows that for the first time the nation is on track to meet the goal of a 90 percent high school graduation rate by the Class of 2020 -- if the pace of improvement from 2006 to 2010 is sustained over the next 10 years. The greatest gains have occurred for the students of color and low-income students most affected by the dropout crisis. Many schools, districts and states are making significant gains in boosting high school graduation rates and putting more students on a path to college and a successful career. This progress is often the result of having better data, an understanding of why and where students drop out, a heightened awareness of the consequences to individuals and the economy, a greater understanding of effective reforms and interventions, and real-world examples of progress and collaboration. These factors have contributed to a wider understanding that the dropout crisis is solvable.While progress is encouraging, a deeper look at the data reveals that gains in graduation rates and declines in dropout factory high schools occurred unevenly across states and subgroups of students (e.g. economically disadvantaged, African American, Hispanic, students with disabilities, and students with limited English proficiency). As a result, large "graduation gaps" remain in many states among students of different races, ethnicities, family incomes, disabilities and limited English proficiencies. To repeat the growth in graduation rates in the next ten years experienced in the second half of the last decade, and to ensure progress for all students, the nation must turn its attention to closing the graduation gap by accelerating progress for student subgroups most affected by the dropout crisis.This report outlines the progress made and the challenges that remain. Part 1: The Data analyzes the latest graduation rates and "dropout factory" trends at the state and national levels. Part 2: Progress and Challenge provides an update on the nation's shared efforts to implement the Civic Marshall Plan to reach the goal of at least a 90 percent high school graduation rate for the Class of 2020 and all classes that follow. Part 3: Paths Forward offers recommendations on how to accelerate our work and achieve our goals, with all students prepared for college and career. The report also offers "snapshots" within schools, communities, and organizations from Orlando to Oakland that are making substantial gains in boosting high school graduation rates

A generalized Poloidal-Toroidal decomposition and an absolute measure of helicity

This is the final version. Available on open access from IOP Publishing via the DOI in this recordIn fluid mechanics and magneto-hydrodynamics it is often useful to decompose a vector field into poloidal and toroidal components. In a spherical geometry, the poloidal component contains all of the radial part of the field, while the curl of the toroidal component contains all of the radial current. This paper explores how they work in more general geometries, where space is foliated by nested simply connected surfaces. Vector fields can still be divided into poloidal and toroidal components, but in geometries lacking spherical symmetry it makes sense to further divide the poloidal field into a standard part and a 'shape' term, which in itself behaves like a toroidal field and arises from variations in curvature. The generalised P–T decomposition leads to a simple definition of helicity which does not rely on subtracting the helicity of a potential reference field. Instead, the helicity measures the net linking of the standard poloidal field with the toroidal field as well as the new shape field. This helicity is consistent with the relative helicity in spherical and planar geometries. Its time derivative due to motion of field lines in a surface has a simple and intuitively pleasing form.MB acknowledges STFC grant ST/R000891/1. GH acknowledges support from STFC grant ST/N000714/1

The Dependence of Coronal Loop Heating on the Characteristics of Slow Photospheric Motions

The Parker hypothesis (Parker (1972)) assumes that heating of coronal loops occurs due to reconnection, induced when photospheric motions braid field lines to the point of current sheet formation. In this contribution we address the question of how the nature of photospheric motions affects heating of braided coronal loops. We design a series of boundary drivers and quantify their properties in terms of complexity and helicity injection. We examine a series of long-duration full resistive MHD simulations in which a simulated coronal loop, consisting of initially uniform field lines, is subject to these photospheric flows. Braiding of the loop is continually driven until differences in behaviour induced by the drivers can be characterised. It is shown that heating is crucially dependent on the nature of the photospheric driver - coherent motions typically lead to fewer large energy release events, while more complex motions result in more frequent but less energetic heating events

Toll-like Receptor 3 Regulates Neural Stem Cell Proliferation by Modulating the Sonic Hedgehog Pathway

Toll-like receptor 3 (TLR3) signaling has been implicated in neural stem/precursor cell (NPC) proliferation. However, the molecular mechanisms involved, and their relationship to classical TLR-mediated innate immune pathways, remain unknown. Here, we report investigation of the mechanics of TLR3 signaling in neurospheres comprised of epidermal growth factor (EGF)-responsive NPC isolated from murine embryonic cerebral cortex of C57BL/6 (WT) or TLR3 deficient (TLR3−/−) mice. Our data indicate that the TLR3 ligand polyinosinic-polycytidylic acid (PIC) negatively regulates NPC proliferation by inhibiting Sonic Hedgehog (Shh) signaling, that PIC induces apoptosis in association with inhibition of Ras-ERK signaling and elevated expression of Fas, and that these effects are TLR3-dependent, suggesting convergent signaling between the Shh and TLR3 pathways

Non-global Structure of the O({\alpha}_s^2) Dijet Soft Function

High energy scattering processes involving jets generically involve matrix elements of light- like Wilson lines, known as soft functions. These describe the structure of soft contributions to observables and encode color and kinematic correlations between jets. We compute the dijet soft function to O({\alpha}_s^2) as a function of the two jet invariant masses, focusing on terms not determined by its renormalization group evolution that have a non-separable dependence on these masses. Our results include non-global single and double logarithms, and analytic results for the full set of non-logarithmic contributions as well. Using a recent result for the thrust constant, we present the complete O({\alpha}_s^2) soft function for dijet production in both position and momentum space.Comment: 55 pages, 8 figures. v2: extended discussion of double logs in the hard regime. v3: minor typos corrected, version published in JHEP. v4: typos in Eq. (3.33), (3.39), (3.43) corrected; this does not affect the main result, numerical results, or conclusion

Vortex line topology during vortex tube reconnection

This paper addresses reconnection of vortex tubes, with particular focus on the topology of the vortex lines (field lines of the vorticity). This analysis of vortex line topology reveals previously undiscovered features of the reconnection process, such as the generation of many small flux rings, formed when reconnection occurs in multiple locations in the vortex sheet between the tubes. Consideration of three-dimensional reconnection principles leads to a robust measurement of the reconnection rate, even once instabilities break the symmetry. It also allows us to identify internal reconnection of vortex lines within the individual vortex tubes. Finally, the introduction of a third vortex tube is shown to render the vortex reconnection process fully three-dimensional, leading to a fundamental change in the topological structure of the process. An additional interesting feature is the generation of vorticity null points.Comment: Accepted for publication in Physical Review Fluid

Flux and field line conservation in 3--D nonideal MHD flows: Remarks about criteria for 3--D reconnection without magnetic neutral points

We make some remarks on reconnection in plasmas and want to present some calculations related to the problem of finding velocity fields which conserve magnetic flux or at least magnetic field lines. Hereby we start from views and definitions of ideal and non-ideal flows on one hand, and of reconnective and non-reconnective plasma dynamics on the other hand. Our considerations give additional insights into the discussion on violations of the frozen--in field concept which started recently with the papers by Baranov & Fahr (2003a; 2003b). We find a correlation between the nonidealness which is given by a generalized form of the Ohm's law and a general transporting velocity, which is field line conserving.Comment: 9 pages, 2 figures, submitted to Solar Physic

2015 Building a Grad Nation Report: Progress and Challenge in Ending the High School Dropout Epidemic

This sixth annual report to the nation highlights the significant progress that has been made, but also the serious challenges that remain – closing gaping graduation gaps between various student populations; tackling the challenge in key states and school districts; and keeping the nation's focus on ensuring that all students – whom Robert Putnam calls "our kids" – have an equal chance at the American Drea

Pattern formation and selection in quasi-static fracture

Fracture in quasi-statically driven systems is studied by means of a discrete spring-block model. Developed from close comparison with desiccation experiments, it describes crack formation induced by friction on a substrate. The model produces cellular, hierarchical patterns of cracks, characterized by a mean fragment size linear in the layer thickness, in agreement with experiments. The selection of a stationary fragment size is explained by exploiting the correlations prior to cracking. A scaling behavior associated with the thickness and substrate coupling, derived and confirmed by simulations, suggests why patterns have similar morphology despite their disparity in scales.Comment: 4 pages, RevTeX, two-column, 5 PS figures include