School Accountability and Administrator Incentives in California

Examines the impact of the No Child Left Behind Act's incentives for principals, superintendents, and school boards on accountability. Calls for transparency on the effectiveness of schools, districts, and interventions in improving student achievement

Improving School Accountability in California

Proposes a value-added model for assessing schools that measures contributions to student learning based on whether average test scores are higher or lower than expected, given prior achievement and other characteristics. Outlines implementation issues

Valence band study of thermoelectric Zintl-phase SrZn_2Sb_2 and YbZn_2Sb_2: X-ray photoelectron spectroscopy and density functional theory

The electronic structure of SrZn_2Sb_2 and YbZn_2Sb_2 is investigated using density functional theory and high-resolution x-ray photoemission spectroscopy. Both traditional Perdew-Burke-Ernzerhof and state-of-the-art hybrid Heyd-Scuseria-Ernzerhof functionals have been employed to highlight the importance of proper treatment of exchange-dependent Zn  3d states, Yb 4f states, and band gaps. The role of spin-orbit corrections in light of first-principles transport calculations are discussed and previous claims of Yb^(3+) valence are investigated with the assistance of photoelectron as well as scanning and transmission electron microscopy

Ca_3AlSb_3: an inexpensive, non-toxic thermoelectric material for waste heat recovery

Thermoelectric materials directly convert thermal energy into electrical energy, offering a promising solid-state solution for waste heat recovery. For thermoelectric devices to make a significant impact on energy and the environment the major impediments are the efficiency, availability and toxicity of current thermoelectric materials. Typically, efficient thermoelectric materials contain heavy elements such as lead and tellurium that are toxic and not earth abundant. Many materials with unusual structures containing abundant and benign elements are known, but remain unexplored for thermoelectric applications. In this paper we demonstrate, with the discovery of high thermoelectric efficiency in Ca_3AlSb_3, the use of elementary solid-state chemistry and physics to guide the search and optimization of such materials

A systematic search for close supermassive black hole binaries in the Catalina Real-Time Transient Survey

Hierarchical assembly models predict a population of supermassive black hole (SMBH) binaries. These are not resolvable by direct imaging but may be detectable via periodic variability (or nanohertz frequency gravitational waves). Following our detection of a 5.2 year periodic signal in the quasar PG 1302-102 (Graham et al. 2015), we present a novel analysis of the optical variability of 243,500 known spectroscopically confirmed quasars using data from the Catalina Real-time Transient Survey (CRTS) to look for close (< 0.1 pc) SMBH systems. Looking for a strong Keplerian periodic signal with at least 1.5 cycles over a baseline of nine years, we find a sample of 111 candidate objects. This is in conservative agreement with theoretical predictions from models of binary SMBH populations. Simulated data sets, assuming stochastic variability, also produce no equivalent candidates implying a low likelihood of spurious detections. The periodicity seen is likely attributable to either jet precession, warped accretion disks or periodic accretion associated with a close SMBH binary system. We also consider how other SMBH binary candidates in the literature appear in CRTS data and show that none of these are equivalent to the identified objects. Finally, the distribution of objects found is consistent with that expected from a gravitational wave-driven population. This implies that circumbinary gas is present at small orbital radii and is being perturbed by the black holes. None of the sources is expected to merge within at least the next century. This study opens a new unique window to study a population of close SMBH binaries that must exist according to our current understanding of galaxy and SMBH evolution.Comment: 29 pages, 10 figures, accepted for publication in MNRAS - this version contains extended table and figur

Improving Usability of Social and Behavioral Sciences’ Evidence: A Call to Action for a National Infrastructure Project for Mining Our Knowledge

Over the last century, the social and behavioral sciences have accumulated a vast storehouse of knowledge with the potential to transform society and all its constituents. Unfortunately, this knowledge has accumulated in a form (e.g., journal papers) and scale that makes it extremely difficult to search, categorize, analyze, and integrate across studies. In this commentary based on a National Science Foundation-funded workshop, we describe the social and behavioral sciences’ knowledge-management problem. We discuss the knowledge-scale problem and how we lack a common language, a common format to represent knowledge, a means to analyze and summarize in an automated way, and approaches to visualize knowledge at a large scale. We then describe that we need a collaborative research program between information systems, information science, and computer science (IICS) researchers and social and behavioral science (SBS) researchers to develop information system artifacts to address the problem that many scientific disciplines share but that the social and behavioral sciences have uniquely not addressed

A Coupled Experimental and Computational Approach to Quantify Deleterious Hemodynamics, Vascular Alterations, and Mechanisms of Long-Term Morbidity in Response to Aortic Coarctati

Introduction Coarctation of the aorta (CoA) is associated with morbidity despite treatment. Although mechanisms remain elusive, abnormal hemodynamics and vascular biomechanics are implicated. We present a novel approach that facilitates quantification of coarctation-induced mechanical alterations and their impact on vascular structure and function, without genetic or confounding factors. Methods Rabbits underwent thoracic CoA at 10 weeks of age (~ 9 human years) to induce a 20 mm Hg blood pressure (BP) gradient using permanent or dissolvable suture thereby replicating untreated and corrected CoA. Computational fluid dynamics (CFD) was performed using imaging and BP data at 32 weeks to quantify velocity, strain and wall shear stress (WSS) for comparison to vascular structure and function as revealed by histology and myograph results. Results Systolic and mean BP was elevated in CoA compared to corrected and control rabbits leading to vascular thickening, disorganization and endothelial dysfunction proximally and distally. Corrected rabbits had less severe medial thickening, endothelial dysfunction, and stiffening limited to the proximal region despite 12 weeks of normal BP (~ 4 human years) after the suture dissolved. WSS was elevated distally for CoA rabbits, but reduced for corrected rabbits. Discussion These findings are consistent with alterations in humans. We are now poised to investigate mechanical contributions to mechanisms of morbidity in CoA using these methods

Black Holes in Supergravity: the non-BPS Branch

We construct extremal, spherically symmetric black hole solutions to 4D supergravity with charge assignments that preclude BPS-saturation. In particular, we determine the ground state energy as a function of charges and moduli. We find that the mass of the non-BPS black hole remains that of a marginal bound state of four basic constituents throughout the entire moduli space and that there is always a non-zero gap above the BPS bound.Comment: 29 pages, one appendix, no figures; v2. few comments and references added and a missing sign included; v3. further references adde

The Globular Cluster System of NGC 5128 II. Ages, Metallicities, Kinematics, and Formation

We present a study of the nearby post-merger giant elliptical galaxy, NGC 5128 (Centaurus A), in which we use the properties of its globular cluster (GC) and planetary nebula (PN) systems to constrain its evolution. Using photometric and spectroscopic data for 215 GCs presented in Paper I, we study trends in age, metallicity, and kinematics for the GC system. We confirm that the GC metallicity distribution is bimodal, and show that these two sub-populations have different properties. Using spectral line index measurements of the brightest clusters, the metal-poor GCs have old ages like the Milky Way globular clusters, while the metal-rich GCs have H-beta line-strengths that could be interpreted as a mean age of ~5 (+3/-2) Gyr. Both populations appear to have [Mg/Fe] ratios consistent with that of the Galactic GC system, although this quantity is not very well-constrained. The kinematics of the metal-rich GCs are similar to those of the planetary nebulae, exhibiting significant rotation about a misaligned axis, while the metal-poor GCs have a higher velocity dispersion and show a weaker kinematic correlation with the field stars. The total gravitating mass of NGC 5128 derived from the GCs is in excellent agreement with the value derived from stellar (PN) kinematics. We suggest that these and other data support a picture in which the main body of NGC 5128 was formed 3-8 Gyr ago by the dissipational merger of two unequal-mass disk galaxies supplemented by the continual accretion of both gas-rich and gas-poor satellites.Comment: 15 pages, 21 figures (figures 14-20 best viewed in color), accepted for publication in the Astrophysical Journa

How do early-life adverse childhood experiences mediate the relationship between childhood socioeconomic conditions and adolescent health outcomes in the UK?

Background Both adverse childhood experiences (ACEs) and adverse childhood socioeconomic conditions (SECs) in early life are associated with poor outcomes across the life course. However, the complex interrelationships between childhood SECs and ACEs are unclear, as are the consequences for health outcomes beyond childhood. We therefore assessed the extent to which early-life ACEs mediate the relationship between SECs and socioemotional behavioural problems, cognitive disability and overweight/obesity in adolescence. Methods We used longitudinal data from the UK Millennium Cohort Study (MSC). Outcomes assessed at age 14 were socioemotional behavioural problems, cognitive disability and overweight/obesity. SECs at birth were measured by maternal education. Potentially mediating ACEs measured up to 5 years were verbal and physical maltreatment, parental drug use, domestic violence, parental divorce, maternal mental illness and high frequency of parental alcohol use. We used counterfactual mediation analysis to assess the extent to which ACEs mediate the association between SECs at birth and behavioural, cognitive and physical outcomes at age 14, estimating total (TE), natural direct and indirect effects, and mediated proportions. Results Children with disadvantaged SECs were more likely to have socioemotional behavioural problems (relative risk (RR) 3.85, 95% CI 2.48 to 5.97), cognitive disability (RR 3.87, 95% CI 2.33 to 6.43) and overweight/obesity (RR 1.61, 95% CI 1.32 to 1.95), compared to those with more advantaged SECs. Overall, 18% of the TE of SECs on socioemotional behavioural problems was mediated through all ACEs investigated. For cognitive disability and overweight/obese, the proportions mediated were 13% and 19%, respectively. Conclusion ACEs measured up to age 5 years in the MCS explained about one-sixth of inequalities in adolescents behavioural, cognitive and physical outcomes