Mathematical Model of Heavy Metal Transfer and Transport in Lake Erie

This study was supported in part by the Office of Water Resources Technology, U.S. Department of Interior under project A-045-OHIO(print) vii, 141 p. : ill. ; 27 cm.Numerical integration of mathematical functions representing the concentration of mercury, chromium and nickel in Lake Erie sediments indicate that 3.3 x 10^5 kg Hg, 1.8 x 10^7 kg Cr, and 1.2 x 10^7 kg Ni have been added to the sediments through man's activities. Most of the mercury, chromium and nickel are contained in the sediments of western Lake Erie. A mathematical model of sediment transport in Lake Erie shows that most of the heavy metals in western Lake Erie sediments probably originated from the Detroit metropolitan area and was input via the Detroit River. The sediment dispersal patterns are as follows: 1) the Detroit River sediment spreads southeastward over most of the western basin, 2) the Maumee River sediment is held within 15 miles of the Ohio shore, and 3) the Cuyahoga River sediment travels northeastward along the south shore of the lake. Attempts to model the transfer and transport of mercury within the ecosystem resulted in partial success. Very little transfer results between the sediments and other phases within the system. In contrast the exchange of mercury between the benthic organisms and other trophic and abiotic levels is very rapid.Abstract -- Key Words -- Project Personnel -- Introduction -- Mercury, Chromium and Nickel in Lake Erie Sediments -- Sediment Transport Model -- Model of Mercury Transfer and Transport in Lake Erie - Appendice

Size Matters: The Number of Prostitutes and the Global HIV/AIDS Pandemic

Background. HIV/AIDS prevalence rates across countries of the world vary more than 500-fold from.06 % in Hungary to 33.4% in Swaziland. One of the most cited research papers in the field, utilizing cross country regression analysis to analyze other correlates with this HIV prevalence data, is flawed in that it weights each country’s results by the country’s population. Methodology/Principal Findings. Based on cross-country linear and multiple regressions using newly gathered data from UNAIDS, the number of female commercial sex workers as a percentage of the female adult population is robustly positively correlated with countrywide HIV/AIDS prevalence levels. Confirming earlier studies, female illiteracy levels, gender illiteracy differences and income inequality within countries are also significantly positively correlated with HIV/AIDS levels. Muslims as a percentage of the population, itself highly correlated with country circumcision rates and previously found to be negatively correlated with HIV/AIDS prevalence, is insignificant when the percentage of commercial sex workers in a population is included in the analysis. Conclusions/Significance. This paper provides strong evidence that when conducted properly, cross country regression data does not support the theory that male circumcision is the key to slowing the AIDS epidemic. Rather, it is the number of infected prostitutes in a country that is highly significant and robust in explaining HIV prevalence levels across countries. An explanation is offered for why Africa has been hit the hardest by the AIDS pandemic and why there appears to be very little correlation between HIV/AIDS infection rates and country wealth

Predicted Colors and Flux Densities of Protostars in the Herschel PACS and SPIRE Filters

Upcoming surveys with the Herschel Space Observatory will yield far-IR photometry of large samples of young stellar objects, which will require careful interpretation. We investigate the color and luminosity diagnostics based on Herschel broad-band filters to identify and discern the properties of low-mass protostars. We compute a grid of 2,016 protostars in various physical congurations, present the expected flux densities and flux density ratios for this grid of protostars, and compare Herschel observations of three protostars to the model results. These provide useful constraints on the range of colors and fluxes of protostar in the Herschel filters. We find that Herschel data alone is likely a useful diagnostic of the envelope properties of young starsComment: Part of HOPS KP papers to the Herschel special A&A issu

Detailed GPC analysis of poly(N-isopropylacrylamide) with core cross-linked star architecture

Core cross-linked star shaped polymers possess unique physical properties that can be utilized as drug transporters for biomedical applications. However, detailed analysis of these polymer structures is not straightforward. Herein, we employ multi-detector gel permeation chromatography (GPC) to elucidate structural features of cross-linked stars prepared from the polymerisation of NIPAM via Cu(0)-mediated Reversible Deactivation Radical Polymerisation. Furthermore, we aim to show how varying the arm length and the core size of the star polymers can not only affect their structural properties but also their capacity to encapsulate drug-like molecules

One-pot synthesis of amphiphilic multiblock poly(2-oxazoline)s via para-fluoro-thiol click reactions

A clickable initiator, pentafluoro benzyl bromide, has been investigated for the cationic ring opening polymerization of poly(2-oxazolines). Additionally, the clickable alpha end group was then utilized in a para-fluoro-thiol click reaction to synthesise linear diblock, tetrablock, multiblock copolymers as well as star shaped poly(2-oxazoline)s using dithiol compounds as terminating agents. Thus, a one-pot approach combining the para-fluoro-thiol click reaction and direct termination of the poly(2-oxazoline) living chain end with 4,4-thiobisbenzenethiol has been performed to prepare multiblock copolymers of poly(2-ethyl-2-oxazoline) (PEtOx) and poly((2-ethyl-2-oxazoline)-b-(2-methyl-2-oxazoline) (PEtOx-mb-PMeOx). All obtained polymers were characterized by Size Exclusion Chromatography (SEC), 1H Nuclear Magnetic Resonance (NMR) and Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-ToF) mass spectrometry. Last but not least, the self-assembly properties of prepared amphiphilic polymers were studied with DLS and TEM. Nanoparticles with a diameter ranging from 184 nm to 250 nm were observed in TEM for PEtOx-mb-PMeOx copolymers

Event categories in the EDELWEISS WIMP search experiment

Four categories of events have been identified in the EDELWEISS-I dark matter experiment using germanium cryogenic detectors measuring simultaneously charge and heat signals. These categories of events are interpreted as electron and nuclear interactions occurring in the volume of the detector, and electron and nuclear interactions occurring close to the surface of the detectors(10-20 mu-m of the surface). We discuss the hypothesis that low energy surface nuclear recoils,which seem to have been unnoticed by previous WIMP searches, may provide an interpretation of the anomalous events recorded by the UKDMC and Saclay NaI experiments. The present analysis points to the necessity of taking into account surface nuclear and electron recoil interactions for a reliable estimate of background rejection factors.Comment: 11 pages, submitted to Phys. Lett.

TEMPERATURE AND LEVEL DENSITY PARAMETER OF EVAPORATION RESIDUES PRODUCED IN THE REACTION 165Ho + 600 MeV 20Ne

Evaporative and preequilibrium neutrons emitted from evaporation residues in the reaction Ho + 600 MeV neon are exploited to deduce the thermal excitation energy E* and temperature T of the residues. From these quantities the level density parameter is deduced at a temperature of 4.1 MeV

Background discrimination capabilities of a heat and ionization germanium cryogenic detector

The discrimination capabilities of a 70 g heat and ionization Ge bolometer are studied. This first prototype has been used by the EDELWEISS Dark Matter experiment, installed in the Laboratoire Souterrain de Modane, for direct detection of WIMPs. Gamma and neutron calibrations demonstrate that this type of detector is able to reject more than 99.6% of the background while retaining 95% of the signal, provided that the background events distribution is not biased towards the surface of the Ge crystal. However, the 1.17 kg.day of data taken in a relatively important radioactive environment show an extra population slightly overlapping the signal. This background is likely due to interactions of low energy photons or electrons near the surface of the crystal, and is somewhat reduced by applying a higher charge-collecting inverse bias voltage (-6 V instead of -2 V) to the Ge diode. Despite this contamination, more than 98% of the background can be rejected while retaining 50% of the signal. This yields a conservative upper limit of 0.7 event.day^{-1}.kg^{-1}.keV^{-1}_{recoil} at 90% confidence level in the 15-45 keV recoil energy interval; the present sensitivity appears to be limited by the fast ambient neutrons. Upgrades in progress on the installation are summarized.Comment: Submitted to Astroparticle Physics, 14 page