Ecotoxicology of metal-hydrocarbon mixtures in benthic invertebrates

Metal-hydrocarbon mixtures are becoming increasingly prevalent in natural environments due to expanding industrial activity and urbanization. The ecotoxicology of metal-hydrocarbon mixtures in benthic environments is of particular concern because both classes of contaminants partition to sediments and can thereby exert toxic effects in benthic organisms. Mixtures of dissimilar chemicals (including metals and hydrocarbons) are broadly hypothesized to elicit independent toxic effects however; this hypothesis has little supporting data. The purpose of this dissertation was to test this hypothesis for metal-hydrocarbon mixtures using environmentally relevant exposures and to determine mechanisms for observed interactive effects. Sediment and water-only bioassays were conducted employing the toxic heavy metal cadmium (Cd) and the polynuclear aromatic hydrocarbon phenanthrene (Phen) as model toxicants. Lethal and sublethal effects of singular and combined contaminants were examined in two freshwater species, the epibenthic amphipod Hyalella azteca and the bulk deposit-feeding benthic oligochaete Ilyodrilus templetoni. When interactive toxicity was observed, mixture effects on contaminant bioavailability, bioaccumulation and elimination were tested. As well, mixture effects on bioenergetics parameters were investigated and kinetic modeling was conducted to establish the source of mixture-mediated changes in contaminant bioaccumulation in I. templetoni. Cadmium-Phen mixtures caused independent effects in water-only exposures, but when incorporated into sediments, elicited synergistic lethal effects in H. azteca and antagonistic lethal effects in I. templetoni. Interactive effects were likely caused by Phen-mediated alterations in Cd bioaccumulation that resulted from changes in exposure via feeding. The current basis for assessing ecotoxicological effects of contaminant mixtures in natural environments relies heavily on models derived from dosage-based mixture toxicology with considerably less emphasis on environmental science and biology. Understanding how contaminants interact toxicologically is important, but does not provide all the information necessary for assessing effects in natural populations that encounter contaminant mixtures in a diversity of natural environments. My experiments indicate that exposure source may be more important than dosage-based toxicological interactions in determining contaminant mixture effects in sediment environments. If this trend is widespread, understanding how species are exposed, determining the route of uptake and understanding how environmental characteristics affect exposure may be more important in determining mixture effects than mixture toxicology

Taxation

Covers cases on inheritance taxation of insurance proceeds and on property previously exempt

Wills and Estates

Covers cases on the impossibility of performance in precedent conditions in the construction of wills, on persons entitled to letters of administration, and on proof of lost or destroyed wills

Dispersal of meiofauna in a turbulent tidal creek

Traditionally meiofauna have been viewed as strictly infaunal organisms adapted for life between sediment grains. Recent evidence has shown that marine meiofauna also occur in the water column. A set of field experiments investigated processes controlling the abundance of meiofauna in the water column. The transport of meiofauna in a tidal creek was identified to be primarily a passive process resulting from mechanical removal due to current scour. Drifting meiofauna included interstitial, burrowing, and epibenthic species. Copepods, foraminiferans, and juvenile bivalves were suspended in greatest numbers relative to their sediment abundances. Suspension of meiofauna was greatest for species residing in the upper sediment layers and/or occasionally crawling about on the sediment surface. Suspended meiofauna and sediment were well-mixed within the water column, suggesting that behavioral control over water column dispersal was limited once the animals were in the water. Suspension of meiofauna was not a function of winds, time of day, lunar cycle (neap vs. spring tides), or the abundance of meiofauna in the sediment. The abundance of meiofauna in the water was determined primarily by the magnitude of the friction velocity (u.). The emerging concept is that in habitats where water currents are strong enough to lead to sediment scour, meiofauna dispersal is a two-step process with erosion rather than active water column entry (modified by behavior patterns for some species) and subsequent mixing and transport as passive particles

Global Universal Basic Skills: Current Deficits and Implications for World Development

How far is the world away from ensuring that every child obtains the basic skills needed to be internationally competitive? And what would accomplishing this mean for world development? Based on the micro data of international and regional achievement tests, we map achievement onto a common (PISA) scale. We then estimate the share of children not achieving basic skills for 159 countries that cover 98.1% of world population and 99.4% of world GDP. We find that at least two-thirds of the world's youth do not reach basic skill levels, ranging from 24% in North America to 89% in South Asia and 94% in Sub-Saharan Africa. Our economic analysis suggests that the present value of lost world economic output due to missing the goal of global universal basic skills amounts to over $700 trillion over the remaining century, or 11% of discounted GDP

Relaxation rates and collision integrals for Bose-Einstein condensates

Near equilibrium, the rate of relaxation to equilibrium and the transport properties of excitations (bogolons) in a dilute Bose-Einstein condensate (BEC) are determined by three collision integrals, $\mathcal{G}^{12}$, $\mathcal{G}^{22}$, and $\mathcal{G}^{31}$. All three collision integrals conserve momentum and energy during bogolon collisions, but only $\mathcal{G}^{22}$ conserves bogolon number. Previous works have considered the contribution of only two collision integrals, $\mathcal{G}^{22}$ and $\mathcal{G}^{12}$. In this work, we show that the third collision integral $\mathcal{G}^{31}$ makes a significant contribution to the bogolon number relaxation rate and needs to be retained when computing relaxation properties of the BEC. We provide values of relaxation rates in a form that can be applied to a variety of dilute Bose-Einstein condensates.Comment: 18 pages, 4 figures, accepted by Journal of Low Temperature Physics 7/201

The Geology and Geochemistry of the Agamenticus Complex, York, Maine

Guidebook for field trips in southern and west-central Maine, October 13, 14 and 15, 1989: New England Intercollegiate Geological Conference 81st annual meeting: Trip A-1; C-

Effects of Pituitary Stalk-transection and Type of Barrier on Pituitary and Luteal Function During the Estrous Cycle of the Ewe

Effects of pituitary stalk-transection on plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH) prolactin (PRL) and progesterone were investigated during the estrous cycle of ewes. Pituitary stalk (SS) or sham (SH) transection was performed on day 1 (estrus = day 0) of the estrous cycle. A Teflon or Silastic barrier was placed between the cut ends of the stalk to prevent reorganization of the portal vasculature. Immediately following surgery, pulsatile administration of gonadotropin releasing hormone (GnRH, 200 ng/hr) or .9% NaCl was initiated and continued for the duration of the experiment. Estradiol benzoate (EB, 50 μg im) was administered to all ewes on day 3. Mean concentrations of LH were greater in SS ewes than in SH ewes (P\u3c.05). There was a trend (P=.06) for the concentration of LH to be higher in ewes with Teflon compared with Silastic barriers between the cut ends of the stalk. Infusion of GnRH elevated concentrations of LH in both SS and SH ewes (P\u3c.05). Concentrations of progesterone were reduced (P\u3c.01) in saline-infused SS ewes while infusion of GnRH in SS ewes maintained concentrations of progesterone similar to saline-infused SH ewes. The concentrations of FSH or PRL were unaffected by SS, type of barrier or treatment with GnRH. Administration of EB failed to induce a surge of LH except in a SH ewe infused with GnRH. Ewes were more responsive to infusion of GnRH following SS than after SH as reflected by increased plasma concentrations of LH and progesterone

Factors associated with age of first sex among women screened for an observational contraceptive vaginal ring study in Kisumu, Kenya, 2014

Sex at an early age can have later life negative health outcomes. Insights on early sexual activity may help in the development of future health-promotion products and interventions related to pregnancy and sexually transmitted infections (STIs) prevention. Among Kenyan women participating in a contraceptive vaginal ring study, we determined: (1) the proportion with first sex at ≤15 years (early sex) and (2) factors associated with early sex. Baseline data collection and testing for pregnancy, STIs, and HIV were undertaken. A log-binomial or a modified Poisson regression was used to estimate univariable prevalence ratios and multivariable adjusted prevalence ratios (aPRs). Among 332 women aged 18-34 years, the median age of first sex was 16 years, with 40.1% experiencing early sex. Overall, 29.8% reported an older first sex partner (≥5 years); 83.9% indicated lack of readiness or intentions at first sex; and 56.2% received money, gifts, or favors as part of first sex. Early sex was more prevalent among inherited widows (a Luo cultural practice, aPR 1.49), gift recipients (aPR 1.38), women with a forced/unwanted sex history (aPR 1.42), or those with a partner of unknown or positive HIV status in the past 3 months (aPR 1.45). Sex before or at the age 15 may be associated with higher sexual risk behaviors. Complex power and gender relations may additionally influence exposure to sexual risk in our research setting. Les rapports sexuels à un âge précoce peuvent avoir des conséquences négatives sur la santé plus tard dans la vie. Des informations sur l'activité sexuelle précoce peuvent aider au développement de futurs produits et interventions de promotion de la santé liés à la prévention de la grossesse et des infections sexuellement transmissibles (IST). Parmi les femmes kényanes participant à une étude sur l'anneau vaginal contraceptif, nous avons déterminé: (1) la proportion de femmes ayant eu un premier rapport sexuel à ≤15 ans (rapports sexuels précoces) et (2) les facteurs associés aux rapports sexuels précoces. La collecte de données de base et le dépistage de la grossesse, des IST et du VIH ont été entrepris. Une régression log binomiale ou une régression de Poisson modifiée a été utilisée pour estimer les ratios de prévalence univariés et les ratios de prévalence ajustés multivariables (aPR). Chez 332 femmes âgées de 18 à 34 ans, l'âge médian du premier rapport sexuel était de 16 ans, 40,1% ayant eu des rapports sexuels précoces. Dans l'ensemble, 29,8% ont déclaré un premier partenaire sexuel plus âgé (≥ 5 ans); 83,9% ont indiqué un manque de préparation ou d'intentions lors du premier rapport sexuel; et 56,2% ont reçu de l'argent, des cadeaux ou des faveurs dans le cadre de leur premier rapport sexuel. Les rapports sexuels précoces étaient plus fréquents chez les veuves héritées (une pratique culturelle Luo, aPR 1,49), les bénéficiaires de cadeaux (aPR 1,38), les femmes ayant des antécédents sexuels forcés / non désirés (aPR 1,42) ou celles dont le partenaire était séropositif ou inconnu en les 3 derniers mois (aPR 1,45). Les rapports sexuels avant ou à 15 ans peuvent être associés à des comportements sexuels à risque plus élevé. Le pouvoir complexe et les relations de genre peuvent également influencer l'exposition aux risques sexuels dans notre contexte de recherche

Coherent Propagation of Polaritons in Semiconductor Heterostructures: Nonlinear Pulse Transmission in Theory and Experiment

The influence of coherent optical nonlinearities on polariton propagation effects is studied within a theory-experiment comparison. A novel approach that combines a microscopic treatment of the boundary problem in a sample of finite thickness with excitonic and biexcitonic nonlinearities is introduced. Light-polarization dependent spectral changes are analyzed for single-pulse transmission and pump-probe excitation