Chemical and Toxicological Analyses of Lake Calumet (Cook County, Illinois) Sediments

HWRIC Project 88-048NTIS PB90-16072

Summary of Toxicological Data for Aquatic Organisms of Illinois

The data presented in this report contain Information on toxicity testing performed on organisms that could be found In aquatic habitats in Illinois. To compile this information a thorough list of all aquatic organisms in Illinois was required. This was constructed through literature searches and personal communication with scientists who collect and identify Illinois aquatic specimens. Each species name was used to search a database which contained toxicity information on aquatic organisms. No toxicological Information was found for many Illinois species. For most organisms, all available information retrieved from the database is presented. For species on which extensive toxicological research has been performed, data showing 96 hour LC50 or EC50 values and chronic testing values constitute the bulk of the records. In addition to records detailing toxicity values and experimental conditions, a list of tested chemical compounds and organisms is included. Literature citing observations and identification of aquatic organisms within Illinois was the most valuable resource in compiling a list of Illinois aquatic species. Staff of the Illinois Natural History Survey were helpful in recommending the most useful publications, making available their own field lists, and helping to update taxonomy and nomenclature from older reports. In particular we would like to acknowledge Don Webb, Larry Page, Warren Brigham, Mark Wetzel, Kevin Cummings, and Allison Brigham from the INHS Faunistics section and Michael Henebry from the section of Aquatic Biology. To retrieve toxicity data on the aquatic organisms of Illinois, a Chemical Information System, Inc. database, AQUIRE (Aquatic Information Retrieval System), was employed. AQUIRE contains data extracted from publications dealing with the toxic effects of chemical substances on aquatic organisms. Each Latin species name from the compiled Illinois list was used to search records in the database. If AQUIRE matched a record with the species name, the record was stored. If there were an excessive number of matching records, the search was narrowed by specifying particular regimens and/or effective endpoint types. Ultimately a printout of the records pertaining to each organism was produced. The data contained In this report are duplications of the AQUIRE records obtained for Illinois organisms. The taxonomy, habitat, and Illinois distribution is listed immediately preceding the AQUIRE records compiled for each species. These records have been substantially reduced from their original size and are arranged by chemical compound in alphabetical and/or numerical order.published or submitted for publicationis peer reviewe

Stochastic Gene Expression in a Lentiviral Positive Feedback Loop: HIV-1 Tat Fluctuations Drive Phenotypic Diversity

Stochastic gene expression has been implicated in a variety of cellular processes, including cell differentiation and disease. In this issue of Cell, Weinberger et al. (2005) take an integrated computational-experimental approach to study the Tat transactivation feedback loop in HIV-1 and show that fluctuations in a key regulator, Tat, can result in a phenotypic bifurcation. This phenomenon is observed in an isogenic population where individual cells display two distinct expression states corresponding to latent and productive infection by HIV-1. These findings demonstrate the importance of stochastic gene expression in molecular "decision-making."Comment: Supplemental data available as q-bio.MN/060800

Weyl's Lagrangian in teleparallel form

The main result of the paper is a new representation for the Weyl Lagrangian (massless Dirac Lagrangian). As the dynamical variable we use the coframe, i.e. an orthonormal tetrad of covector fields. We write down a simple Lagrangian - wedge product of axial torsion with a lightlike element of the coframe - and show that this gives the Weyl Lagrangian up to a nonlinear change of dynamical variable. The advantage of our approach is that it does not require the use of spinors, Pauli matrices or covariant differentiation. The only geometric concepts we use are those of a metric, differential form, wedge product and exterior derivative. Our result assigns a variational meaning to the tetrad representation of the Weyl equation suggested by J. B. Griffiths and R. A. Newing

The Knudsen temperature jump and the Navier-Stokes hydrodynamics of granular gases driven by thermal walls

Thermal wall is a convenient idealization of a rapidly vibrating plate used for vibrofluidization of granular materials. The objective of this work is to incorporate the Knudsen temperature jump at thermal wall in the Navier-Stokes hydrodynamic modeling of dilute granular gases of monodisperse particles that collide nearly elastically. The Knudsen temperature jump manifests itself as an additional term, proportional to the temperature gradient, in the boundary condition for the temperature. Up to a numerical pre-factor of order unity, this term is known from kinetic theory of elastic gases. We determine the previously unknown numerical pre-factor by measuring, in a series of molecular dynamics (MD) simulations, steady-state temperature profiles of a gas of elastically colliding hard disks, confined between two thermal walls kept at different temperatures, and comparing the results with the predictions of a hydrodynamic calculation employing the modified boundary condition. The modified boundary condition is then applied, without any adjustable parameters, to a hydrodynamic calculation of the temperature profile of a gas of inelastic hard disks driven by a thermal wall. We find the hydrodynamic prediction to be in very good agreement with MD simulations of the same system. The results of this work pave the way to a more accurate hydrodynamic modeling of driven granular gases.Comment: 7 pages, 3 figure

Seed Treatment for Corn Diseases

In Iowa three destructive corn diseases attack the seed, namely, Dfplc·dfa dry rot, Baslsporlum dry rot and Gibberella dry rot. These dry rots are best known on the ear, but also may attack any part of the plant, lncluding the seed and seedling. The Injury to the seed and to the subsequent yield has been measured during the last six years in 25 counties and found to average 5 bushels per acre. These dry rot organisms llve over on the old stubble In the soil and on the seed and attack the next season\u27s crop

A Continuum Description of Rarefied Gas Dynamics (I)--- Derivation From Kinetic Theory

We describe an asymptotic procedure for deriving continuum equations from the kinetic theory of a simple gas. As in the works of Hilbert, of Chapman and of Enskog, we expand in the mean flight time of the constituent particles of the gas, but we do not adopt the Chapman-Enskog device of simplifying the formulae at each order by using results from previous orders. In this way, we are able to derive a new set of fluid dynamical equations from kinetic theory, as we illustrate here for the relaxation model for monatomic gases. We obtain a stress tensor that contains a dynamical pressure term (or bulk viscosity) that is process-dependent and our heat current depends on the gradients of both temperature and density. On account of these features, the equations apply to a greater range of Knudsen number (the ratio of mean free path to macroscopic scale) than do the Navier-Stokes equations, as we see in the accompanying paper. In the limit of vanishing Knudsen number, our equations reduce to the usual Navier-Stokes equations with no bulk viscosity.Comment: 16 page

Greenhouse gas balance over thaw-freeze cycles in discontinuous zone permafrost

Peat in the discontinuous permafrost zone contains a globally significant reservoir of carbon that has undergone multiple permafrost-thaw cycles since the end of the mid-Holocene (~3700 years before present). Periods of thaw increase C decomposition rates which leads to the release of CO2 and CH4 to the atmosphere creating potential climate feedback. To determine the magnitude and direction of such feedback, we measured CO2 and CH4 emissions and modeled C accumulation rates and radiative fluxes from measurements of two radioactive tracers with differing lifetimes to describe the C balance of the peatland over multiple permafrost-thaw cycles since the initiation of permafrost at the site. At thaw features, the balance between increased primary production and higher CH4 emission stimulated by warmer temperatures and wetter conditions favors C sequestration and enhanced peat accumulation. Flux measurements suggest that frozen plateaus may intermittently (order of years to decades) act as CO2 sources depending on temperature and net ecosystem respiration rates, but modeling results suggest that—despite brief periods of net C loss to the atmosphere at the initiation of thaw—integrated over millennia, these sites have acted as net C sinks via peat accumulation. In greenhouse gas terms, the transition from frozen permafrost to thawed wetland is accompanied by increasing CO2 uptake that is partially offset by increasing CH4 emissions. In the short-term (decadal time scale) the net effect of this transition is likely enhanced warming via increased radiative C emissions, while in the long-term (centuries) net C deposition provides a negative feedback to climate warming

Recollapse of the closed Tolman spacetimes

The closed-universe recollapse conjecture is studied for the spherically symmetric spacetimes. It is proven that there exists an upper bound to the lengths of timelike curves in any Tolman spacetime that possesses $S^3$ Cauchy surfaces and whose energy density is positive. Furthermore, an explicit bound is constructed from the initial data for such a spacetime.Comment: 25 pages, REVTeX, NCSU-MP-930