Comparisons between the squash bug egg parasitoids Ooencyrtus anasae and O. sp. (Hymenoptera: Encyrtidae): development, survival,and sex ratio in relation to temperature

Citation: Tracy, J. L., and J. R. Nechols. 1987. “Comparisons Between the Squash Bug Egg Parasitoids Ooencyrtus Anasae and O. Sp. (Hymenoptera: Encyrtidae): Development, Survival, and Sex Ratio in Relation to Temperature.” Environmental Entomology 16 (6): 1324–29. https://doi.org/10.1093/ee/16.6.1324.Laboratory investigations of the gregarious squash bug egg parasitoids Ooencyrtus anasae and O. n. sp. near anasae (O. sp.) were conducted at 20.8, 23.0, and 26.6°C. In both species, total developmental periods (egg to eclosed adult) were inversely related to temperature. Temperature had no significant influence on survivorship, progeny production, or sex ratio. At each temperature, O. anasae developed and emerged about a day earlier and produced a significantly higher percentage of female progeny (77%) than did O. sp. (60%). Both parasitoids deposited an average of three (2-7) progeny per host. However, O. anasae consistently deposited more female eggs per host than did O. sp. Proportion of females produced per host by O. anasae tended to increase directly with number of hosts parasitized, but no such relationship was observed in O. sp. Total preimaginal survivorship in both parasitoids was about 89%. In O. sp., male progeny that developed without females emerged about a day later at all temperatures and had a lower pharate adult survivorship than did males that developed in hosts with female siblings

Reduced O diffusion through Be doped Pt electrodes

Using first principles electronic structure calculations we screen nine elements for their potential to retard oxygen diffusion through poly-crystalline Pt (p-Pt) films. We determine that O diffuses preferentially as interstitial along Pt grain boundaries (GBs). The calculated barriers are compatible with experimental estimates. We find that Be controls O diffusion through p-Pt. Beryllium segregates to Pt GBs at interstitial (i) and substitutional (s) sites. i-Be is slightly less mobile than O and it repels O, thus stuffing the GB. s-Be has a high diffusion barrier and it forms strong bonds to O, trapping O in the GB. Experiments confirm our theoretical predictions.Comment: 3 pages, 2 figure

Multi-Step Cascade Annihilations of Dark Matter and the Galactic Center Excess

If dark matter is embedded in a non-trivial dark sector, it may annihilate and decay to lighter dark-sector states which subsequently decay to the Standard Model. Such scenarios - with annihilation followed by cascading dark-sector decays - can explain the apparent excess GeV gamma-rays identified in the central Milky Way, while evading bounds from dark matter direct detection experiments. Each 'step' in the cascade will modify the observable signatures of dark matter annihilation and decay, shifting the resulting photons and other final state particles to lower energies and broadening their spectra. We explore, in a model-independent way, the effect of multi-step dark-sector cascades on the preferred regions of parameter space to explain the GeV excess. We find that the broadening effects of multi-step cascades can admit final states dominated by particles that would usually produce too sharply peaked photon spectra; in general, if the cascades are hierarchical (each particle decays to substantially lighter particles), the preferred mass range for the dark matter is in all cases 20-150 GeV. Decay chains that have nearly-degenerate steps, where the products are close to half the mass of the progenitor, can admit much higher DM masses. We map out the region of mass/cross-section parameter space where cascades (degenerate, hierarchical or a combination) can fit the signal, for a range of final states. In the current work, we study multi-step cascades in the context of explaining the GeV excess, but many aspects of our results are general and can be extended to other applications.Comment: 18 pages, 15 figures, 2 tables; comments welcome. Updated to published versio

Model-Independent Indirect Detection Constraints on Hidden Sector Dark Matter

If dark matter inhabits an expanded "hidden sector", annihilations may proceed through sequential decays or multi-body final states. We map out the potential signals and current constraints on such a framework in indirect searches, using a model-independent setup based on multi-step hierarchical cascade decays. While remaining agnostic to the details of the hidden sector model, our framework captures the generic broadening of the spectrum of secondary particles (photons, neutrinos, e+e- and antiprotons) relative to the case of direct annihilation to Standard Model particles. We explore how indirect constraints on dark matter annihilation limit the parameter space for such cascade/multi-particle decays. We investigate limits from the cosmic microwave background by Planck, the Fermi measurement of photons from the dwarf galaxies, and positron data from AMS-02. The presence of a hidden sector can change the constraints on the dark matter annihilation cross section by up to an order of magnitude in either direction (although the effect can be much smaller). We find that generally the bound from the Fermi dwarfs is most constraining for annihilations to photon-rich final states, while AMS-02 is most constraining for electron and muon final states; however in certain instances the CMB bounds overtake both, due to their approximate independence of the details of the hidden sector cascade. We provide the full set of cascade spectra considered here as publicly available code with examples at http://web.mit.edu/lns/research/CascadeSpectra.html.Comment: Published version. Added analysis on interplay between indirect detection bounds and the Galactic Center GeV excess. Added antiproton ratio bound

Changes in the Spatial Allocation of Cropland in the Ft. Cobb Watershed as a Result of Environmental Restrictions

Pollution runoff estimates from SWAT are used in a mathematical programming model to optimally model site-specific crop and conservation practices for pollution abatement in the Ft. Cobb watershed in Southwestern Oklahoma. Results indicate the tradeoffs between producer income, sediment and nutrient runoff and the spatial allocation of crops in the watershed.Environmental Economics and Policy,

Classroom Collective Bargaining Simulation : How Close to the Real Thing

Les jeux et les simulations sont devenus un moyen populaire d'enseignement au cours de la dernière décennie. Leur utilisation est fort bien appropriée à un processus comme celui des négociations collectives. Plusieurssketches de négociations sont disponibles et en usage dans plusieurs campus universitaires à l'heure actuelle. Le présent article décrit l'une de ces saynètes telle qu'on la joue à l'université de Washington.Malgré leur popularité et leur valeur apparente au premier coup d'oeil, les jeux et les simulations n'ont été rarement soumis à une véritable épreuve quant à leur caractère réaliste. L'étude des différents aspects de la négociation collective en tant que le comportement des parties est en jeu fournit une occasion de vérifier si les perceptions des négociations simulées se comparent aux perceptions des véritables négociations tant du côté des salariés que du côté des employeurs.On a découvert qu'il n'y avait pas de différence significative entre les principales réparties des aspirants négociateurs et celles des négociateurs syndicaux, surtout si ces derniers sont inexpérimentés. Les différences entre les étudiants et les négociateurs vraiment expérimentés, notamment les négociateurs patronaux, variaient surtout selon leur degré d'expérience et de maturité et en ce que les négociations « jouées » comportent une responsabilité moindre et n'offrent pas d'occasion d'avancement. Dans l'ensemble, on est arrivé à la conclusion que les négociations simulées se rapprochaient pas mal des négociations réelles. En conclusion, l'article suggère quelques moyens de les rendre encore plus réalistes.The use of games and simulations as means of instruction is particularly appropriate to a behavioral process such as collective bargaining. The author describes, analyses and evaluates one which is used at the University of Washingto

Race, Age, and Neighborhood Socioeconomic Status in Low Birth Weight Disparities Among Adolescent Mothers: An Intersectional Inquiry

Introduction: Few studies examined socioeconomic contributors to racial disparities in low birth weight outcomes between African-American and Caucasian adolescent mothers. This cross-sectional study examined the intersections of maternal racial status, age, and neighborhood socioeconomic status in explaining these disparities in low birth weight outcomes across a statewide sample of adolescent mothers. Methods: Using data from the North Carolina State Center of Health Statistics for 2010-2011, birth cases for 16,472 adolescents were geocoded by street address and linked to census-tract information from the 2010 United States Census. Multilevel models with interaction terms were used to identify significant associations between maternal racial status, age, and neighborhood socioeconomic status (as defined by census-tract median household income) and low birth weight outcomes across census tracts. Results: Significant racial differences were identified in which African-American adolescents had greater odds of low birth weight outcomes than Caucasian adolescents (OR=1.88, 95% CI 1.64, 2.15). Although racial disparities in low birth weight outcomes remained significant in context of maternal age and neighborhood socioeconomic status, the greatest disparities were found between African-American and Caucasian adolescents that lived in areas of higher socioeconomic status (p Conclusion: These findings indicate that racial disparities in low birth weight outcomes among adolescent mothers can vary by neighborhood socioeconomic status. Further investigations using intersectional frameworks are needed for examining the relationships between neighborhood socioeconomic status and birth outcome disparities among infants born to adolescent mothers