Applications of contaminant fate and bioaccumulation models in assessing ecological risks of chemicals: a case study for gasoline hydrocarbons

Mass balance models of chemical fate and transport can be applied in ecological risk assessments for quantitative estimation of concentrations in air, water, soil, and sediment. These concentrations can, in turn, be used to estimate organism exposures and ultimately internal tissue concentrations that can be compared to mode-of-action-based critical body residues that induce toxic effects. From this comparison, risks to the exposed organism can be evaluated. To demonstrate the use of fate models in ecological risk assessment, we combine the EQuilibrium Criterion (EQC) environmental fate model with a simple screening level biouptake model for three representative organisms: a bird, a mammal, and a fish. This effort yields estimates of internal body concentrations that can be compared with levels known to elicit toxic effects. As an illustration, we present an analysis of 24 hydrocarbon components of gasoline that differ in properties but are assumed to elicit toxicity by a common narcotic mode of action. Results demonstrate that differences in chemical properties and mode of entry into the environment lead to profound differences in the efficiency of transport from emission to target biota. We discussthe implications of these results and draw attention to the insights gained about regional fate and ecological risks associated with gasoline. This approach is suitable for assessing single chemicals or mixtures that have similar modes of action. We conclude that the model-based methodologies presented are widely applicable for screening level ecological risk assessments that support effective chemicals management.     

Sex differences in empathy and related capacities.

Reviews the literature on sex differences in empathy (defined as vicarious affective responding to the emotional state of another) and related capacities (affective role taking and decoding of nonverbal cues). The literature is discussed according to method used to assess empathy and affective role taking. Where appropriate, meta-analyses were also computed. In general, sex differences in empathy were found to be a function of the methods used to assess empathy. There was a large sex difference favoring women when the measure of empathy was self-report scales; moderate differences (favoring females) were found for reflexive crying and self-report measures in laboratory situations; and no sex differences were evident when the measure of empathy was either physiological or unobtrusive observations of nonverbal reactions to another's emotional state. Moreover, few sex differences were found for children's affective role taking and decoding abilities. (156 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Demonstration of a method for the direct determination of polycyclic aromatic hydrocarbons in submerged sediments

We describe the development of a novel method for real-time in situ characterization of polycyclic aromatic hydrocarbons (PAHs) in submerged freshwater sediments. Laser-induced fluorescence (LIF) spectroscopy, a mature technique for PAH characterization in terrestrial sediments, was adapted for shipboard use. A cone penetrometer-type apparatus was designed for probe penetration at a constant rate (1 cm/s) to a depth of 3 m. A field-portable LIF system was used for in situ measurements in which the output of a pulsed excimer laser was transmitted by optical fiber to a sapphire window (6.4-mm o.d.) in the probe wall; fluorescent emission was collected by a separate optical fiber for transmission to the spectrometer on deck. Four wavelengths (340, 390, 440, 490 nm) were selected via optical delay lines, and multiple-wavelength waveforms were created. These multiple-wavelength waveforms contain information on the fluorescence frequency, intensity, and emission decay rate. Field testing was conducted at 10 sites in Milwaukee Harbor (total PAH concentrations ranged from approximately 10 to 650 microg/g); conventional sediment core samples were collected concurrently. The core samples were analyzed by EPA methods 3545 (pressurized fluid extraction, PFE) and 8270C (gas chromatography-mass spectrometry, GC-MS) for PAHs. A partial least-squares regression (PLSR) model wasthen created based on laboratory LIF measurements and PFE-GC-MS of the core samples. The PLSR model was applied to the in situ field test data, and 13 of the 16 EPA-regulated PAHs were quantified with a relative error of <30% overall (the remaining three PAHs were found at levels insufficient to quantify). We additionally describe preliminary source apportionment relationships that were revealed by the PLSR model for the in situ LIF measurements.     

Chromium-doped forsterite: dispersion measurement with white-light interferometry

Using a Michelson white-light interferometer, we measure the group-delay dispersion and third-order dispersion coefficients, d2(phi)/d(omega)2 and d3(phi)/d(omega)3, of chromium-doped forsterite (Cr:Mg2SiO4) over wavelengths of 1050-1600 nm for light polarized along both the c and b crystal axes. In this interval, the second-order dispersion for the c axis ranges from 35 fs2/mm to -14 fs2/mm, and the third-order dispersion ranges from 36 fs3/mm to 142 fs3/mm. For the b axis the second-order dispersion ranges from 35 fs2/mm to -15 fs2/mm and the third-order from 73 fs3/mm to 185 fs3/mm. Our data are relevant for the development of optimized dispersion compensation tools for Cr:Mg2SiO4 femtosecond lasers. These measurements help to clarify previously published results and show some significant discrepancies that existed, especially in the third-order dispersion. Our results should furthermore be useful to build up an analytic expression for the index of refraction of chromium forsterite.     

Daunorubicin‐Loaded DNA Origami Nanostructures Circumvent Drug‐Resistance Mechanisms in a Leukemia Model

Many cancers show primary or acquired drug resistance due to the overexpression of efflux pumps. A novel mechanism to circumvent this is to integrate drugs, such as anthracycline antibiotics, with nanoparticle delivery vehicles that can bypass intrinsic tumor drug‐resistance mechanisms. DNA nanoparticles serve as an efficient binding platform for intercalating drugs (e.g., anthracyclines doxorubicin and daunorubicin, which are widely used to treat acute leukemias) and enable precise structure design and chemical modifications, for example, for incorporating targeting capabilities. Here, DNA nanostructures are utilized to circumvent daunorubicin drug resistance at clinically relevant doses in a leukemia cell line model. The fabrication of a rod‐like DNA origami drug carrier is reported that can be controllably loaded with daunorubicin. It is further directly verified that nanostructure‐mediated daunorubicin delivery leads to increased drug entry and retention in cells relative to free daunorubicin at equal concentrations, which yields significantly enhanced drug efficacy. Our results indicate that DNA origami nanostructures can circumvent efflux‐pump‐mediated drug resistance in leukemia cells at clinically relevant drug concentrations and provide a robust DNA nanostructure design that could be implemented in a wide range of cellular applications due to its remarkably fast self‐assembly (≈5 min) and excellent stability in cell culture conditions.     

Leveraging decision‐making tools in capacity building planning: The Indonesian scientific network case

Abstract

The development of investment alternatives for the Government of Indonesia's proposed scientific network forms the background to this case. The goal was to rationalize a structure for developing and sustaining a broad‐based network capable of serving scientists throughout the country, including very remote areas. It became clear that one approach could combine both technological as well as entrepreneurial elements, since the data communications linkages for serving scientists could also be available for private customers. The process of defining and costing out this approach was a textbook example of a bottom‐up analysis, beginning with customer needs and working toward structures to satisfy the needs. The World Bank and the Government of Indonesia are in the process of implementing several features of the recommended system. The proposed approach can ultimately pay for itself through private sector revenues for user services. While the context of the decision is telecommunications, the methodology is appropriate for many decision‐making situations. Samples of actual data and bottom‐line results are discussed.     

Theoretical and statistical derivation of a screener for the behavioral assessment of executive functions in children.

The problem of valid measurement of psychological constructs remains an impediment to scientific progress, and the measurement of executive functions is not an exception. This study examined the statistical and theoretical derivation of a behavioral screener for the estimation of executive functions in children from the well-established Behavior Assessment System for Children (BASC). The original national standardization sample of the BASC–Teacher Rating Scales for children ages 6 through 11 was used (N = 2,165). Moderate-to-high internal consistency was obtained within each factor (.80–.89). A panel of experts was used for content validity examination. A confirmatory factor analysis model with 25 items loading on 4 latent factors (behavioral control, emotional control, attentional control, and problem solving) was developed, and its statistical properties were examined. The multidimensional model demonstrated adequate fit, and it was deemed invariant after configural, metric, and scalar measurement invariance tests across sex and age. Given its strong psychometric properties, with further tests of item validity, this instrument promises future clinical and research utility for the screening of executive functions in school-age children. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

LexAGen: An interactive incremental scanner generator

This paper describes LexAGen, an interactive scanner generator which is the first component of an interactive compiler generation environment. LexAGen can generate fast scanners for languages whose tokens can be specified by regular grammars. However, LexAGen also supports several context-sensitive programming language constructs such as nested comments and the interaction between floating-point numbers and the range operator in Modula-2. In addition, LexAGen includes a fast new algorithm for keyword identification. However, the most important and novel aspects of LexAGen are that it constructs scanners incrementally and that specifications can be executed anytime for validation testing. LexAGen specifications are expressed and entered interactively in a restricted BNF format (no left recursion). All syntactic errors and token conflicts are detected and reported immediately as LexAGen incrementally constructs a deterministic finite automaton to represent the scanner. At any time, the user can test the scanner fragment which has been entered by supplying text to be scanned. Alternatively, the user can generate a C-code scanner from the automaton. The generated automaton uses a direct execution approach and is quite fast. LexAGen is implemented in Smalltalk-80. Its extensive use of interactive graphics makes it very easy to use. In addition, the object-oriented paradigm of Smalltalk-80 is the basis for the incremental analysis, the error detection scheme and an intermediate representation which can be easily modified to generate scanners in other target languages such as Pascal, Modula-2 and Ada.