4,621 research outputs found
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
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
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,
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
Resummed Photon Spectra for WIMP Annihilation
We construct an effective field theory (EFT) description of the hard photon
spectrum for heavy WIMP annihilation. This facilitates precision predictions
relevant for line searches, and allows the incorporation of non-trivial energy
resolution effects. Our framework combines techniques from non-relativistic
EFTs and soft-collinear effective theory (SCET), as well as its multi-scale
extensions that have been recently introduced for studying jet substructure. We
find a number of interesting features, including the simultaneous presence of
SCET and SCET modes, as well as collinear-soft modes
at the electroweak scale. We derive a factorization formula that enables both
the resummation of the leading large Sudakov double logarithms that appear in
the perturbative spectrum, and the inclusion of Sommerfeld enhancement effects.
Consistency of this factorization is demonstrated to leading logarithmic order
through explicit calculation. Our final result contains both the exclusive and
the inclusive limits, thereby providing a unifying description of these two
previously-considered approximations. We estimate the impact on experimental
sensitivity, focusing for concreteness on an SU(2) triplet fermion dark
matter - the pure wino - where the strongest constraints are due to a search
for gamma-ray lines from the Galactic Center. We find numerically significant
corrections compared to previous results, thereby highlighting the importance
of accounting for the photon spectrum when interpreting data from current and
future indirect detection experiments.Comment: 55+25 pages, 11+2 figures; v3, updated an expression in the appendix
to make it applicable at higher order - no impact on the results in this wor
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