135 research outputs found
The Impact of Quasi-Regulatory Mechanisms on Polluting Behavior: Evidence from Pollution Prevention Programs and Toxic Releases
To date, there is little convincing evidence on the effectiveness of “quasi-regulatory” mechanisms. Here I investigate how quasi-regulatory policies known as pollution prevention (“P2”) programs affect toxic pollution. I construct a data base on state-level P2 programs as well as the 1990 federal Pollution Prevention Act (PPA) and exploit variation in state adoption dates and program characteristics to study their effects on facility-level toxic releases. I find strong evidence that these mechanisms can affect pollution outcomes. In particular, I find that (1) the 1990 PPA has had a significant effect on toxic releases; (2) state programs geared to reducing the costs of P2 activities led to significant reductions in toxic releases; and (3) the response to P2 programs that increased the regulators’ ability to monitor polluting behavior could either increase or decrease reported releases, depending on the regulators’ ability to verify the accuracy of the reported releases.TRI, Quasi-Regulation, Voluntary Programs, Toxic Pollution
Toxic exposure in America: estimating fetal and infant health outcomes
We examine the effect of toxic exposure on U.S. infant and fetal mortality rates between 1989 and 2002 from toxic pollution released by facilities reporting to the Toxic Release Inventory (TRI). Unlike previous studies, we control for toxic pollution from mobile sources and from non-TRI reporting facilities. We find significant adverse effects of TRI exposure on infant mortality. There is evidence that health effects vary across media: air and water having a larger impact than land pollution. And, within air, we find that releases of carcinogens are particularly problematic for infant health outcomes. We estimate that the average county-level decreases in TRI concentrations between 1988 and 2002 saved in excess of 13,800 infant lives.Newborn infants - Mortality ; Public welfare
Gains from Trade in the Optimal Control of Environmental Externalities: Evidence from Acid Rain Abatement in the Eastern United States and Canada
In this paper I investigate the properties of a system of internationally traded "licenses to pollute" for the control of acid rain in the Eastern United States and Canada. I report estimates of the costs to the United States and Canada of achieving a 15 percent reduction in acid rain concentrations under a joint tradeable permit system for sulfur dioxide emissions. I use point-source data for the 200 largest sulfur dioxide emitters in each of Canada and the United States, transfer coefficients that relate emissions in different regions to acid rain concentrations in specified "sensitive receptor" regions, and fitted cost functions for each point source, to estimate the costs facing each country under different acid rain abatement programs. The estimates show (1) that an autarkic program of abatement in either country induces significant spillover benefits in the other that lead to the potential for "freeriding," and (2) that, contrary to widespread beliefs, a joint program of abatement would lead to substantial cost savings for both the United States and Canada. The results also document, however, large differentials in the gains that would accrue to each country, suggesting that there may be serious obstacles, in the form of difficulties in arriving at a division of the gains from trade, to achieving agreement on a joint program of abatement.Center for Research on Economic and Social Theory, Department of Economics, University of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/100658/1/ECON132.pd
The Origin and In Situ Identification of Uncultured Gut Bacteria in Fourth-Instar Larvae of the Red Imported Fire Ant, Solenopsis invicta (Hymenoptera: Formicidae)
This study corroborated the findings of Lee et al. (2008) and relied on culture-independent techniques, particularly 16S rDNA sequencing. Results from the study demonstrated that ants in captivity completely change their gut bacterial diversity strongly supports the conclusion that fire ant gut bacteria are environmental in origin. Bacteria in the fourth-instar larvae were present because they were consumed with food sources. From molecular data, a differing list of bacteria from each colony with different branching and clustering among bacterial clades in the phylogenetic trees were found. Different bacterial diversity and evenness was found in all colonies, which provided evidence against the idea of the presence of obligate bactrial endosymbionts in Solenopis invicta guts. Obligate endosymbiont elimination through the use of broad-spectrum antibiotics did not significant affect ant mortality when compared to the untreated controls. This study did not find bacteriocytes in the midgut epithelium of fire ants. Microscopic observations did not locate any bacteriocytes in fourth-instar S. invicta larvae. All identified bacteria appeared to have been derived from the food or the environment. Though coadapted bacteria and specialized bacteriocytes were not found in the guts of fourth-instar larvae, such specialized organisms may be present elsewhere in the ant. Coadapted symbionts may exist in other parts of the larvae’s body or in other stages of development
#FeesMustFall# movement in the post-apartheid era: legitimacy battle for leaders
Purpose
Underpinned by institutional legitimacy, this study explores how South African public university senior managers struggled to maintain legitimacy during an unplanned radical change process.
Design/methodology/approach
Gioia's grounded theory analysis approach is employed to analyse interviews with 37 senior managers of public-funded universities in South Africa.
Findings
This study's findings show that a change without proper planning severely damages institutions in all aspects of leadership's normative, empirical, moral and pragmatic legitimacy.
Research limitations/implications
This study contributes to the literature on legitimacy by illustrating the importance of institutional legitimacy during unplanned social change and the factors that negate legitimacy.
Originality/value
Though other legitimacy models have been well developed, they do not apply to such unplanned social change in organisations. This study shows a different angle of the legitimacy crisis under unplanned social change conditions
band Labor Demand: Evidence from the South Coast Air Basin
The devolved nature of environmental regulation provides an excellent opportunity for" estimating the effects of regulation on employment, by generating rich variation in regulation" across regions and over time. We exploit this variation using direct measures of regulation and" plant data. We estimate the employment effects of an unprecedented increase in air quality" regulation in the Los Angeles region, using unregulated plants in other regions years for comparison. While environmental regulation is generally thought to reduce" employment, economic theory is ambiguous on this point, since pollution abatement technologies" may be labor using. We find that air quality regulation induced very expensive investments in" abatement capital for individual plants, especially for oil refineries. Despite these high costs we" find no evidence that environmental regulation decreased labor demand induced plant exit and dissuaded plant entry. If anything, air quality regulation probably inc-" reased employment slightly.
Environmental Regulation and Productivity: Evidence from Oil Refineries
We examine the effect of air quality regulation on the productivity of some of the most heavily regulated manufacturing plants in the United States, the oil refineries of the Los Angeles (South Coast) Air Basin. We use direct measures of local air pollution regulation in this region to estimate their effects on abatement investment. Refineries not subject to these local environmental regulations are used as a comparison group. We study the period of increased regulation between 1979 and 1992. On average each regulation cost 5M per plant on dates of increased stringency. We also construct measures of total factor productivity using plant level data which allow us to observe physical quantities of inputs and outputs for the entire population of refineries. Despite the high costs associated with the local regulations, productivity in the Los Angeles Air Basin refineries rose sharply during the 1987 - 1992 period, a period of decreased refinery productivity in other regions. We conclude that measures of the cost of environmental regulation may be significantly overstated. The gross costs may be far greater than the net cost, as abatement may be productive.
Bone morphogenetic protein 7 sensitizes O6-methylguanine methyltransferase expressing-glioblastoma stem cells to clinically relevant dose of temozolomide.
BackgroundTemozolomide (TMZ) is an oral DNA-alkylating agent used for treating patients with glioblastoma. However, therapeutic benefits of TMZ can be compromised by the expression of O6-methylguanine methyltransferase (MGMT) in tumor tissue. Here we used MGMT-expressing glioblastoma stem cells (GSC) lines as a model for investigating the molecular mechanism underlying TMZ resistance, while aiming to explore a new treatment strategy designed to possibly overcome resistance to the clinically relevant dose of TMZ (35 μM).MethodsMGMT-expressing GSC cultures are resistant to TMZ, and IC50 (half maximal inhibitory concentration) is estimated at around 500 μM. Clonogenic GSC surviving 500 μM TMZ (GSC-500 μM TMZ), were isolated. Molecular signatures were identified via comparative analysis of expression microarray against parental GSC (GSC-parental). The recombinant protein of top downregulated signature was used as a single agent or in combination with TMZ, for evaluating therapeutic effects of treatment of GSC.ResultsThe molecular signatures characterized an activation of protective stress responses in GSC-500 μM TMZ, mainly including biotransformation/detoxification of xenobiotics, blocked endoplasmic reticulum stress-mediated apoptosis, epithelial-to-mesenchymal transition (EMT), and inhibited growth/differentiation. Bone morphogenetic protein 7 (BMP7) was identified as the top down-regulated gene in GSC-500 μM TMZ. Although augmenting BMP7 signaling in GSC by exogenous BMP7 treatment did not effectively stop GSC growth, it markedly sensitized both GSC-500 μM TMZ and GSC-parental to 35 μM TMZ treatment, leading to loss of self-renewal and migration capacity. BMP7 treatment induced senescence of GSC cultures and suppressed mRNA expression of CD133, MGMT, and ATP-binding cassette drug efflux transporters (ABCB1, ABCG2), as well as reconfigured transcriptional profiles in GSC by downregulating genes associated with EMT/migration/invasion, stemness, inflammation/immune response, and cell proliferation/tumorigenesis. BMP7 treatment significantly prolonged survival time of animals intracranially inoculated with GSC when compared to those untreated or treated with TMZ alone (p = 0.0017), whereas combination of two agents further extended animal survival compared to BMP7 alone (p = 0.0489).ConclusionsThese data support the view that reduced endogenous BMP7 expression/signaling in GSC may contribute to maintained stemness, EMT, and chemoresistant phenotype, suggesting that BMP7 treatment may provide a novel strategy in combination with TMZ for an effective treatment of glioblastoma exhibiting unmethylated MGMT
Validation of ISS Floating Potential Measurement Unit Electron Densities and Temperatures
Validation of the Floating Potential Measurement Unit (FPMU) electron density and temperature measurements is an important step in the process of evaluating International Space Station spacecraft charging issues .including vehicle arcing and hazards to crew during extravehicular activities. The highest potentials observed on Space Station are due to the combined VxB effects on a large spacecraft and the collection of ionospheric electron and ion currents by the 160 V US solar array modules. Ionospheric electron environments are needed for input to the ISS spacecraft charging models used to predict the severity and frequency of occurrence of ISS charging hazards. Validation of these charging models requires comparing their predictions with measured FPMU values. Of course, the FPMU measurements themselves must also be validated independently for use in manned flight safety work. This presentation compares electron density and temperatures derived from the FPMU Langmuir probes and Plasma Impedance Probe against the independent density and temperature measurements from ultraviolet imagers, ground based incoherent scatter radar, and ionosonde sites
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