Large temporal variations of energetic electron intensities at mid-latitudes in the outer radiation zone Progress report

Variations of electron flux density observations by Explorer 12 and 1

The Relationship of Educational, Economic & Social Characteristics of the Degree of Desegregation in the Public Schools of Kentucky

The problem in this study was to examine the relationship of social-climate to the degree of desegregation in the public schools of Kentucky. This study attempted to determine the relationship of educational, economic and social characteristics of those school districts with bi-racial student bodies operating in Kentucky and the degree of desegregation experienced voluntarily by those districts during the period from 1955-56 school year through the 1963-64 school year

Risk-Sharing in Retiree Medical Benefits

Retiree medical care expenditures in the United States are growing at a rapid rate, while and the retired portion of the population is increasing. This puts pressure on government and employer programs providing retiree health care coverage. Retirees also face increasing challenges in gaining access to affordable coverage, particularly before eligibility for Medicare. In this chapter we assess prospects for US retiree health coverage and the challenges, risks, and roles of employers, Medicare, and retirees in providing and financing it. We discuss both traditional approaches to retiree health benefits, where the employer assumes most risk, and new defined contribution approaches, where significant risk is shifted to the retiree. We also review government benefits for retirees including new Medicare prescription drug benefits. We model future retiree health care costs and opportunities to save before retiring, highlighting public policy obstacles and issues for employer-provided retiree health benefit

Factors Affecting the Spatial Distribution of Black Mangrove on the Dredged-Material or “Spoil” Islands in the Lower Laguna Madre of Texas

Research was conducted to evaluate the spatial distribution of black mangrove (Avicennia germinans) on the dredged-material or “spoil” islands of the Lower Laguna Madre of Texas. Aerial color-infrared (CIR) photographs revealed the presence of black mangrove stands on many of the islands located south of the Arroyo Colorado (a distributary of the Rio Grande which empties into the Laguna Madre), but failed to detect significant mangrove stands on islands located north of the Arroyo. Analysis of CIR photographs and supervised image classifications for individual islands suggested a concentration of black mangrove along western shorelines and relatively low interior areas of islands, although relatively small and localized mangrove stands were clearly evident along eastern shorelines at several locations. These observations were consistent with ground surveys which indicated significantly higher mangrove densities along western vs eastern shorelines of selected islands (0.6 and 0.1 plants/m2, respectively; P \u3c 0.05), but no difference between ratios of small to large plants in stands located along western vs eastern shorelines (1.6 and 1.4, respectively; P\u3e0.05). The most plausible explanation for these trends is that wave action caused by prevailing southeasterly winds during most of the year may impede or prevent the establishment of black mangrove propagules (germinated „seeds‟) along eastern shorelines of islands which otherwise constitute suitable habitat for A. germinans. If this interpretation is correct, development of planting strategies designed to facilitate establishment of black mangrove stands along shorelines subject to turbulent wave action will be a requisite to the use of this important native plant species for erosion prevention and mitigation on spoil islands in the Lower Laguna Madre

Rates of agonism among female primates: a cross-taxon perspective

Agonism is common in group-living animals, shaping dominance relationships and ultimately impacting individual tness. Rates of agonism vary considerably among taxa, however, and explaining this variation has been central in ecological models of female social relationships in primates. Early iterations of these models posited a link to diet, with more frequent agonism predicted in frugivorous species due to the presumed greater contestability of fruits relative to other food types. Although some more recent studies have suggested that dietary categories may be poor predictors of contest competition among primates, to date there have been no broad, cross-taxa comparisons of rates of female–female agonism in relation to diet. This study tests whether dietary variables do indeed pre- dict rates of female agonism and further investigates the role of group size (i.e., number of competitors) and substrate use (i.e., degree of arboreality) on the frequency of agonism. Data from 44 wild, unprovisioned groups, including 3 strepsirhine species, 3 platyrrhines, 5 colobines, 10 cercopithecines, and 2 hominoids were analyzed using phylogenetically controlled and uncontrolled methods. Results indicate that diet does not predict agonistic rates, with trends actually being in the opposite direction than predicted for all taxa except cercopithecines. In contrast, agonistic rates are positively associated with group size and possibly degree of terrestriality. Competitor density and perhaps the risk of ghting, thus, appear more important than general diet in predicting agonism among female primates. We discuss the implications of these results for socio-ecological hypotheses

Iron availability limits the ocean nitrogen inventory stabilizing feedbacks between marine denitrification and nitrogen fixation

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 21 (2007): GB2001, doi:10.1029/2006GB002762.Recent upward revisions in key sink/source terms for fixed nitrogen (N) in the oceans imply a short residence time and strong negative feedbacks involving denitrification and N fixation to prevent large swings in the ocean N inventory over timescales of a few centuries. We tested the strength of these feedbacks in a global biogeochemical elemental cycling (BEC) ocean model that includes water column denitrification and an explicit N fixing phytoplankton group. In the northern Indian Ocean and over longer timescales in the tropical Atlantic, we find strong stabilizing feedbacks that minimize changes in marine N inventory over timescales of ∼30–200 years. In these regions high atmospheric dust/iron inputs lead to phosphorus limitation of diazotrophs, and thus a tight link between N fixation and surface water N/P ratios. Maintenance of the oxygen minimum zones in these basins depends on N fixation driven export. The stabilizing feedbacks in other regions are significant but weaker owing to iron limitation of the diazotrophs. Thus Fe limitation appears to restrict the ability of N fixation to compensate for changes in denitrification in the current climate, perhaps leading the oceans to lose fixed N. We suggest that iron is the ultimate limiting nutrient leading to nitrogen being the proximate limiting nutrient over wide regions today. Iron stress was at least partially alleviated during more dusty, glacial times, leading to a higher marine N inventory, increased export production, and perhaps widespread phosphorus limitation of the phytoplankton community. The increased efficiency of the biological pump would have contributed to the glacial drawdown in atmospheric CO2.This work was supported by grants from the U.S. National Science Foundation (OCE-0222033 and OCE-0452972). Computations supported by Earth System Modeling Facility (NSF ATM-0321380) and by the Climate Simulation Laboratory at the National Center for Atmospheric Research

Mechanisms controlling dissolved iron distribution in the North Pacific : a model study

Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): G03005, doi:10.1029/2010JG001541.Mechanisms controlling the dissolved iron distribution in the North Pacific are investigated using the Biogeochemical Elemental Cycling (BEC) model with a resolution of approximately 1° in latitude and longitude and 60 vertical levels. The model is able to reproduce the general distribution of iron as revealed in available field data: surface concentrations are generally below 0.2 nM; concentrations increase with depth; and values in the lower pycnocline are especially high in the northwestern Pacific and off the coast of California. Sensitivity experiments changing scavenging regimes and external iron sources indicate that lateral transport of sedimentary iron from continental margins into the open ocean causes the high concentrations in these regions. This offshore penetration only appears under a scavenging regime where iron has a relatively long residence time at high concentrations, namely, the order of years. Sedimentary iron is intensively supplied around continental margins, resulting in locally high concentrations; the residence time with respect to scavenging determines the horizontal scale of elevated iron concentrations. Budget analysis for iron reveals the processes by which sedimentary iron is transported to the open ocean. Horizontal mixing transports sedimentary iron from the boundary into alongshore currents, which then carry high iron concentrations into the open ocean in regions where the alongshore currents separate from the coast, most prominently in the northwestern Pacific and off of California.This work was supported by the U.S. National Science Foundation (EF‐0424599)

Interhemispheric survey of polar cap aurora

This study investigates the interhemispheric nature of polar cap auroras via ultraviolet imaging, combined with particle data, to determine whether they occur on open or closed field lines. Data from the SSUSI (Special Sensor Ultraviolet Spectrographic Imager) instrument on board the DMSP (Defence Meteorological Satellite Program) spacecraft are examined. The DMSP spacecraft are in 90-min orbits; hence, images of each hemisphere are separated by 45min providing a good opportunity for interhemispheric study. 21 polar cap arc (PCA) events are recorded in December 2015 which have particle data from the SSJ/4 particle spectrometer associated with an arc in at least one hemisphere. Nine events are found to contain "arcs" consistent with a closed field line mechanism, that is, arcs associated with an ion signature present in both hemispheres. Six events contained arcs that were consistent with an "open field line" mechanism, that is, they were associated with electron-only precipitation. Events containing arcs that were not consistent with either of these expectations are also explored, including an example of a "non-conjugate" theta aurora and an interesting example of auroral morphology similar to a PCA which is associated with a geomagnetic storm. Seasonal effects are also investigated through a statistical analysis of PCAs over 4 months in 2015. It is found that PCAs are visible in the SSUSI data at least 20% of the time and that it is likely some are missed due to the spacecraft field of view and poor sensitivity in the summer hemisphere due to increased solar illumination

Wildfire effects on soil bacterial community and its potential functions in a permafrost region of Canada

Boreal forests in permafrost zone store significant quantities of carbon that are readily threatened by increases in fire frequency and temperature due to climate change. Soil carbon is primarily released by microbial decomposition that is sensitive to environmental conditions. Under increasing disturbances of wildfire, there is a pressing need to understand interactions between wildfires and microbial communities, thereby to predict soil carbon dynamics. Using Illumina MiSeq sequencing of bacterial 16S rDNA and GeoChip 5.0K, we compared bacterial communities and their potential functions at surface and near-surface permafrost layers across a chronosequence (>100 years) of burned forests in a continuous permafrost zone. Postfire soils in the Yukon and the Northwest Territories, Canada, showed a marked increase in active layer thickness. Our results showed that soil bacterial community compositions and potential functions altered in 3-year postfire forest (Fire3) comparing to the unburned forests. The relative abundance of Ktedonobacteria (Chloroflexi) was higher in Fire3 surface soils, while Alphaproteobacteria and Betaproteobacteria (Proteobacteria) were more abundant in unburned ones. Approximately 37% of the variation in community composition can be explained by abiotic variables, whereas only 2% by biotic variables. Potential functional genes, particularly for carbon degradation and anammox, appeared more frequent in Fire3 than in unburned soils. Variations in functional gene pools were mainly driven by environmental factors (39%) and bacterial communities (20%; at phylum level). Unexpectedly, wildfire solely altered bacterial communities and their functional potentials of the surface layers, not the near-permafrost layers. Overall, the response of bacterial community compositions and functions to wildfire and the environment provides insights to re-evaluate the role of bacteria in decomposition.Peer reviewe

Impacts of increasing anthropogenic soluble iron and nitrogen deposition on ocean biogeochemistry

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 23 (2009): GB3016, doi:10.1029/2008GB003440.We present results from transient sensitivity studies with the Biogeochemical Elemental Cycling (BEC) ocean model to increasing anthropogenic atmospheric inorganic nitrogen (N) and soluble iron (Fe) deposition over the industrial era. Elevated N deposition results from fossil fuel combustion and agriculture, and elevated soluble Fe deposition results from increased atmospheric processing in the presence of anthropogenic pollutants and soluble Fe from combustion sources. Simulations with increasing Fe and increasing Fe and N inputs raised simulated marine nitrogen fixation, with the majority of the increase in the subtropical North and South Pacific, and raised primary production and export in the high-nutrient low-chlorophyll (HNLC) regions. Increasing N inputs alone elevated small phytoplankton and diatom production, resulting in increased phosphorus (P) and Fe limitation for diazotrophs, hence reducing nitrogen fixation (∼6%). Globally, the simulated primary production, sinking particulate organic carbon (POC) export. and atmospheric CO2 uptake were highest under combined increase in Fe and N inputs compared to preindustrial control. Our results suggest that increasing combustion iron sources and aerosol Fe solubility along with atmospheric anthropogenic nitrogen deposition are perturbing marine biogeochemical cycling and could partially explain the observed trend toward increased P limitation at station ALOHA in the subtropical North Pacific. Excess inorganic nitrogen ([NO3 −] + [NH4 +] − 16[PO4 3−]) distributions may offer useful insights for understanding changing ocean circulation and biogeochemistry.This work was supported by funding from NSF grant OCE-0452972 to J. K. Moore and C. S. Zender. Computations were supported by the Earth System Modeling Facility at UCI (NSFATMO321380) and by the Climate Simulation Laboratory at National Center for Atmospheric Research. The National Center for Atmospheric Research is sponsored by the U.S. National Science Foundation. N.M. would like to acknowledge the assistance of NSF– Carbon and Water (ATM-0628472), and N.M., S.D., and C.L. would like to acknowledge the assistance of NASA-IDS (NNX07AL80G)