Emissions of toxic pollutants from compressed natural gas and low sulfur diesel-fueled heavy-duty transit buses tested over multiple driving cycles

The number of heavy-duty vehicles using alternative fuels such as compressed natural gas (CNG) and new low-sulfur diesel fuel formulations and equipped with after-treatment devices are projected to increase. However, few peer-reviewed studies have characterized the emissions of particulate matter (PM) and other toxic compounds from these vehicles. In this study, chemical and biological analyses were used to characterize the identifiable toxic air pollutants emitted from both CNG and low-sulfur-diesel-fueled heavy-duty transit buses tested on a chassis dynamometer over three transient driving cycles and a steady-state cruise condition. The CNG bus had no after-treatment, and the diesel bus was tested first equipped with an oxidation catalyst (OC) and then with a catalyzed diesel particulate filter (DPF). Emissions were analyzed for PM, volatile organic compounds (VOCs; determined on-site), polycyclic aromatic hydrocarbons (PAHs), and mutagenic activity. The 2000 model year CNG-fueled vehicle had the highest emissions of 1,3-butadiene, benzene, and carbonyls (e.g., formaldehyde) of the three vehicle configurations tested in this study. The 1998 model year diesel bus equipped with an OC and fueled with low-sulfur diesel had the highest emission rates of PM and PAHs. The highest specific mutagenic activities (revertants/microg PM, or potency) and the highest mutagen emission rates (revertants/mi) were from the CNG bus in strain TA98 tested over the New York Bus (NYB) driving cycle. The 1998 model year diesel bus with DPF had the lowest VOCs, PAH, and mutagenic activity emission. In general, the NYB driving cycle had the highest emission rates (g/mi), and the Urban Dynamometer Driving Schedule (UDDS) had the lowest emission rates for all toxics tested over the three transient test cycles investigated. Also, transient emissions were, in general, higher than steady-state emissions. The emissions of toxic compounds from an in-use CNG transit bus (without an oxidation catalyst) and from a vehicle fueled with low-sulfur diesel fuel (equipped with DPF) were lower than from the low-sulfur diesel fueled vehicle equipped with OC. All vehicle configurations had generally lower emissions of toxics than an uncontrolled diesel engine. Tunnel backgrounds (measurements without the vehicle running) were measured throughout this study and were helpful in determining the incremental increase in pollutant emissions. Also, the on-site determination of VOCs, especially 1,3-butadiene, helped minimize measurement losses due to sample degradation after collection.     

Effects of STN DBS on memory guided force control in Parkinson's disease (June 2007).

This study examined the control of elbow force in nine patients with Parkinson's disease when visual feedback was available and when visual feedback was removed to determine how medication (Meds) and unilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) affect memory guided force control. Patients were examined in each of four treatment conditions: 1) off treatment; 2) Meds; 3) STN DBS; and 4) Meds plus STN DBS. With visual feedback available, there was no difference in force output across treatment conditions. When visual feedback was removed force output drifted under the target in both the off-treatment and the Meds conditions. However, when on STN DBS or Meds plus STN DBS force output drifted above the target. As such, only STN DBS had a significant effect on force output in the vision removed condition. Increased force output when on STN DBS may have occurred due to disruptions in the basal ganglia-thalamo-cortical circuitry. We suggest that modulation of output of the internal segment of the globus pallidus by STN DBS may drive the effect of STN DBS on memory guided force control.     

A proton and neutron beam polarimeter at SATURNE II

A beam polarimeter using CH₂ and carbon targets has been used to measure proton and neutron beam polarization in the energy range 0.4–2.8 GeV in one of the beam lines at the SATURNE II accelerator. The analyzing power for np-scattering is calibrated against the known analyzing power for pp-scattering by using the polarized deuteron beam to measure simultaneously the asymmetries for scattering of quasifree protons and neutrons in the deuterons. A low level of systematic errors is achieved by pulse to pulse polarization reversal at the ion source of the accelerator, and by measuring left and right scattering simultaneously. The detailed operation procedure and the beam polarizations measured during all experiments from 1981 to 1984 are presented.     

Can Electron Transmission from Aza-Crown Ethers Contribute to Diels-Alder π-Facial Selectivity?

A pair of isodicyclopentafulvenes that carries an exocyclic phenyl group para-substituted with an aza-15-crown-5 or aza-18-crown-6 ring has been prepared. These molecules ( 5a and 5b ) and their respective NaClO₄ ( 11 ) and KSCN ( 12 ) complexes were examined for the extent of π-facial stereoselectivity operational during their Diels-Alder cycloaddition to (Z)-1,2-bis(phenylsulfonyl)ethylene ( 2 ) under conditions of high pressure. Whereas 5a and 5b engage in [4 + 2] condensation with a 2.5–3.1 preference for dienophile capture from the above-plane direction, their complexes show a substantially reduced tendency for doing so (14/13 = 1.2–1.4). However, this response goes contrary to those para-substituent effects previously observed. The linear correlation noted earlier conformed to an increased preference for above-plane cycloaddition to 2 as the para-substituent became progressively more electron-withdrawing. Probable reasons for this seemingly divergent behavior are presented.     

Geomembrane seam nondestructive tests: Construction quality control (CQC) perspective

This paper is intended to present and compare the various commonly used geomembrane field seam nondestructive field testing methods from a construction quality control perspective. The testing methods addressed include: vacuum; air lance; pressure; electrical resistivity; electric spark; and mechanical point stress. The viewpoint presented is one of an installation contractor's quality control testing procedures and the associated limitations, results, data documentation and costs.     

Incrementally maintained network→relational database mapping

An incrementally maintained mapping from a network to a relational database is presented. This mapping may be established either to support the efficient retrieval of data from a network database through a relational interface, or as the first step in a gradual conversion of data and applications from a network to a relational database system. After the mapping has been established, the only data mapped from the network to the relational database are the increments resulting from updates on the network database. The mapping is therefore an efficient alternative to mappings that repeatedly map the results of retrievals through the relational interface from the network database to the relational database. This is in particular the case when the two databases reside on different hosts. Applications on the network database may, under certain restrictions, gradually be moved to the relational database, while the mapping incrementally maintains the relational database for the applications that remain on the network database. A detailed, but generic, account of how to build such a mapping from a network to a relational database is given, including all the algorithms needed and examples of their use.     

The effect of specific growth rate and death rate on monoclonal antibody production in hybridoma chemostat cultures

Experimental data collected from bench-scale chemostat cultures of mouse-mouse hybridoma cells have been used for the development of a kinetic model of monoclonal antibody production. The specific antibody productivity was found to be proportional to the specific death rate, indicating a stimulating effect of stress on the ability of the cells to produce antibody. The death rate was found to be an exponential function of the average cell age in the culture. Furthermore, a Generalized Maintenance Energy (GME) model is proposed, to take account of the effects of culture stress on the nutrient uptake rates. The proposed relationships agreed very well with other mouse-mouse hybridoma chemostat culture data in the literature.     

Adolescent Gambling: Relationships With Parent Gambling and Parenting Practices.

This study explored the possible links between family risk factors (i.e., parent gambling and parenting practices) and adolescent gambling. A community sample of 938 adolescents (496 females and 442 males) completed the South Oaks Gambling Screen Revised for Adolescents (SOGS-RA; K. C. Winters, R. Stinchfield, & J. Fulkerson, 1993b) along with a questionnaire assessing parenting practices. Both parents completed the SOGS (H. R. Lesieur & S. B. Blume, 1987). Results showed that adolescent gambling frequency was related to both parents' gambling frequency and problems. However, adolescent gambling problems were linked only to fathers' severity of gambling problems. Low levels of parental monitoring enhanced adolescents' risk of getting involved in gambling activities and developing related problems. A higher level of inadequate disciplinary practices was also related to greater gambling problems in youth. These links were significant after controlling for socioeconomic status, gender, and impulsivity- hyperactivity problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)