Leading the Initial Implementation Phase of TandemEd in Relationship with the Pittsburgh Public Schools

TandemEd facilitates Black communities to create campaigns that highlight their positive racial identity and self-defined educational purpose. This article examines leadership of the initial implementation phase of the TandemEd community initiative in relationship with the Pittsburgh Public Schools (PPS) focusing primarily on the interactions with the superintendent and executive director of the superintendent’s office. The results included ongoing support from PPS as TandemEd formed a citywide steering committee of highly community legitimated persons, executed a leadership and campaign academy for thirty-five Pittsburgh youth, and facilitated design and delivery of various cable television commercials on identity and purpose in the Greater Pittsburgh region. It utilized the organizational framework established in Reframing Organizations by Lee Bolman and Terrence Deal (1991). The implication being that while a relationship with a public school district at the onset of TandemEd city entry is of value, the greater value is found in first establishing a strong community-legitimated effort and intersecting with the district more deeply in later implementation phases. Additionally, there is transformative value for school and district leaders to be responsive to Black community leadership of education

Enlisting in the Military: The Influential Role of Genetic Factors

Given that enlistment in the U.S. military is completely voluntary, there has been a great deal of interest in identifying the various factors that might explain why some people join the military, whereas others do not. The current study expanded on this line of literature by estimating the extent to which genetic and environmental factors explained variance in the liability for lifetime participation in the military. Analysis of twin pairs drawn from the National Longitudinal Study of Adolescent to Adult Health (Add Health) revealed that 82% of the variance was the result of genetic factors, 18% of the variance was the result of nonshared environmental factors, and none of the variance was accounted for by shared environmental factors. In light of a number of limitations, replication studies are needed to determine the robustness of these findings and whether they are generalizable to other samples and populations

The effect of electrolyte filling method on the performance of dye-sensitized solar cells

The effect of electrolyte filling method on the performance of the dye-sensitized solar cells is investigated with the segmented cell method, a recent technique which is very simple but effective as it can be used to examine all the photovoltaic characteristics. The electrolyte filling techniques compared were single injection, which is typically used in small laboratory cells, and pumping the electrolyte through the cell several times, which is often used for larger cells and modules. Significant photovoltage and photocurrent variations occur with the repeated pumping of the electrolyte in the cell preparation. Transient and charge extraction measurements confirmed that the differences in open circuit voltage were due to the shifts of the TiO2 conduction band and time correlated single photon counting confirmed that the reduction of short circuit current was largely due to reduced electron injection correlated with the increasing conduction band edge in the studied cases. This was interpreted as an effect of molecular filtering by the TiO2 causing an accumulation of electrolyte additives (4-tert-butylpyridine and benzimidazole) near the electrolyte filling hole, the concentration of which increased with repeated pumping of the electrolyte. Interestingly, spatial variations were seen not only in the relative TiO2 conduction band energy but also in the density of trap states. In this contribution it is demonstrated how the changes in the conduction band can be separated from the changes in the density of trap states which is an essential for the correct interpretation of the data.Peer reviewe

Variability in Short Gamma-ray Bursts: Gravitationally Unstable Tidal Tails

Short gamma-ray bursts are thought to result from the mergers of two neutron stars or a neutron star and stellar mass black hole. The final stages of the merger are generally accompanied by the production of one or more tidal "tails" of ejecta, which fall back onto the remnant-disc system at late times. Using the results of a linear stability analysis, we show that if the material comprising these tails is modeled as adiabatic and the effective adiabatic index satisfies $\gamma \ge 5/3$, then the tails are gravitationally unstable and collapse to form small-scale knots. We analytically estimate the properties of these knots, including their spacing along the tidal tail and the total number produced, and their effect on the mass return rate to the merger remnant. We perform hydrodynamical simulations of the disruption of a polytropic (with the polytropic and adiabatic indices $\gamma$ equal), $\gamma =2$ neutron star by a black hole, and find agreement between the predictions of the linear stability analysis and the distribution of knots that collapse out of the instability. The return of these knots to the black hole induces variability in the fallback rate, which can manifest as variability in the lightcurve of the GRB and -- depending on how rapidly the instability operates -- the prompt emission. The late-time variability induced by the return of these knots is also consistent with the extended emission observed in some GRBs.Comment: Small corrections, additional references included to reflect ApJL published versio

Coronal Emission Measures and Abundances for Moderately Active K Dwarfs Observed by Chandra

We have used Chandra to resolve the nearby 70 Oph (K0 V+K5 V) and 36 Oph (K1 V+K1 V) binary systems for the first time in X-rays. The LETG/HRC-S spectra of all four of these stars are presented and compared with an archival LETG spectrum of another moderately active K dwarf, Epsilon Eri. Coronal densities are estimated from O VII line ratios and emission measure distributions are computed for all five of these stars. We see no substantial differences in coronal density or temperature among these stars, which is not surprising considering that they are all early K dwarfs with similar activity levels. However, we do see significant differences in coronal abundance patterns. Coronal abundance anomalies are generally associated with the first ionization potential (FIP) of the elements. On the Sun, low-FIP elements are enhanced in the corona relative to high-FIP elements, the so-called "FIP effect." Different levels of FIP effect are seen for our stellar sample, ranging from 70 Oph A, which shows a prominent solar-like FIP effect, to 70 Oph B, which has no FIP bias at all or possibly even a weak inverse FIP effect. The strong abundance difference exhibited by the two 70 Oph stars is unexpected considering how similar these stars are in all other respects (spectral type, age, rotation period, X-ray flux). It will be difficult for any theoretical explanation for the FIP effect to explain how two stars so similar in all other respects can have coronae with different degrees of FIP bias. Finally, for the stars in our sample exhibiting a FIP effect, a curious difference from the solar version of the phenomenon is that the data seem to be more consistent with the high-FIP elements being depleted in the corona rather than a with a low-FIP enhancementComment: 35 pages, 8 figures, AASTEX v5.0 plus EPSF extensions in mkfig.sty; accepted by Ap

A Quantitative Genetic Analysis of the Associations Among Language Skills, Peer Interactions, and Behavioral Problems in Childhood: Results From a Sample of Twins

A body of empirical research has revealed that there are associations among language skills, peer interactions, and behavioral problems in childhood. At the same time, however, there has been comparatively less research devoted to exploring the mutual unfolding of these factors over the first few years of life. The current study is designed to partially address this gap in the literature by examining how language skills, negative peer interactions, and behavioral problems are interrelated in a sample of twins drawn from the Early Childhood Longitudinal Study–Birth Cohort (ECLS-B). Employing a quantitative genetic framework, the results of the current study revealed that variance in language skills, negative peer interactions, and externalizing behavioral problems were all due to a combination of genetic and environmental factors. Bivariate Cholesky models indicated that most of the covariance among language skills, negative peer interactions, and externalizing behavioral problems was due to common genetic factors. Additional analyses using a modified DeFries–Fulker approach nested within a path model revealed a bidirectional association between negative peer interactions and externalizing behavioral problems, wherein there appeared to be feedback loops between the two. Implications of the results are discussed and avenues for future research are offered

Big events, little change: Extreme climatic events have no region-wide effect on Great Barrier Reef governance

Extreme climatic events trigger changes in ecosystems with potential negative impacts for people. These events may provide an opportunity for environmental managers and decision-makers to improve the governance of social-ecological systems, however there is conflicting evidence regarding whether these actors are indeed able to change governance after extreme climatic events. In addition, the majority of research to date has focused on changes in specific policies or organizations after crises. A broader investigation of governance actors’ activities is needed to more fully understand whether or not crises trigger change. Here we demonstrate the use of a social network analysis of management and decision-making forums (e.g. meetings, partnerships) to reveal the effects of an extreme climatic event on governance of the Great Barrier Reef over an eight-year period. To assess potential shifts in action, we examine the topics of forums and the relative participation and influence of diverse governance actors before, during, and after two back-to-back mass coral bleaching events in 2016 and 2017. Our analysis reveals that there is little change in the topics that receive attention, and in the relative participation and influence of different actor groups in the region. Our research demonstrates that network analysis of forums is useful for analyzing whether or not actors’ activities and priorities evolve over time. Our results provide empirical evidence that governance actors struggle to leverage extreme climate events as windows of opportunity and further research is needed to identify alternative opportunities to improve governance

Measurement of Spin-orbit Misalignment and Nodal Precession for the Planet around Pre-main-sequence Star PTFO 8-8695 from Gravity Darkening

PTFO 8-8695b represents the first transiting exoplanet candidate orbiting a pre-main-sequence star (van Eyken et al. 2012, ApJ, 755, 42). We find that the unusual lightcurve shapes of PTFO 8-8695 can be explained by transits of a planet across an oblate, gravity-darkened stellar disk. We develop a theoretical framework for understanding precession of a planetary orbit's ascending node for the case when the stellar rotational angular momentum and the planetary orbital angular momentum are comparable in magnitude. We then implement those ideas to simultaneously and self-consistently fit two separate lightcurves observed in 2009 December and 2010 December. Our two self-consistent fits yield Mp = 3.0 M_Jup and Mp = 3.6 M_Jup for assumed stellar masses of M* = 0.34 M_☉ and M* = 0.44 M_☉ respectively. The two fits have precession periods of 293 days and 581 days. These mass determinations (consistent with previous upper limits) along with the strength of the gravity-darkened precessing model together validate PTFO 8-8695b as just the second hot Jupiter known to orbit an M-dwarf. Our fits show a high degree of spin-orbit misalignment in the PTFO 8-8695 system: 69° ± 2° or 73°.1 ± 0°.5, in the two cases. The large misalignment is consistent with the hypothesis that planets become hot Jupiters with random orbital plane alignments early in a system's lifetime. We predict that as a result of the highly misaligned, precessing system, the transits should disappear for months at a time over the course of the system's precession period. The precessing, gravity-darkened model also predicts other observable effects: changing orbit inclination that could be detected by radial velocity observations, changing stellar inclination that would manifest as varying vsin i, changing projected spin-orbit alignment that could be seen by the Rossiter–McLaughlin effect, changing transit shapes over the course of the precession, and differing lightcurves as a function of wavelength. Our measured planet radii of 1.64 R_Jup and 1.68 R_Jup in each case are consistent with a young, hydrogen-dominated planet that results from a "hot-start" formation mechanism

MODIS-derived spatiotemporal water clarity patterns in optically shallow Florida Keys waters: A new approach to remove bottom contamination

Retrievals of water quality parameters from satellite measurements over optically shallow waters have been problematic due to bottom contamination of the signals. As a result, large errors are associated with derived water column properties. These deficiencies greatly reduce the ability to use satellites to assess the shallow water environments around coral reefs and seagrass beds. Here, a modified version of an existing algorithm is used to derive multispectral diffuse attenuation coefficient (Kd) from MODIS/Aqua measurements over optically shallow waters in the Florida Keys. Results were validated against concurrent in situ data (Kd(488) from 0.02 to 0.20 m−1, N = 22, R2 = 0.68, Mean Ratio = 0.93, unbiased RMS = 31%), and showed significant improvement over current products when compared to the same in situ data (N = 13, R2 = 0.37, Mean Ratio = 1.61, unbiased RMS = 50%). The modified algorithm was then applied to time series of MODIS/Aqua data over the Florida Keys (in particular, the Florida Keys Reef Tract), whereby spatial and temporal patterns of water clarity between 2002 and 2011 were elucidated. Climatologies, time series, anomaly images, and empirical orthogonal function analysis showed primarily nearshore–offshore gradients in water clarity and its variability, with peaks in both at the major channels draining Florida Bay. ANOVA revealed significant differences in Kd(488) according to distance from shore and geographic region. Excluding the Dry Tortugas, which had the lowest climatological Kd(488), water was clearest at the northern extent of the Reef Tract, and Kd(488) significantly decreased sequentially for every region along the tract. Tests over other shallow-water tropical waters such as the Belize Barrier Reef also suggested general applicability of the algorithm. As water clarity and light availability on the ocean bottom are key environmental parameters in determining the health of shallow-water plants and animals, the validated new products provide unprecedented information for assessing and monitoring of coral reef and seagrass health, and could further assist ongoing regional zoning efforts