Search

BACKGROUND: People who live in dwellings treated with indoor residual spraying (IRS) of DDT [1,1,1-trichIoro-2,2-bis(p-chlorophenyl)ethane] for disease-vector control in the tropics and indigenous populations in the Arctic who comsume marine [...]

BACKGROUND: Most empirical estimates of human elimination kinetics for persistent chemicals reflect apparent elimination half-lives that represent the aggregated effect of intrinsic elimination, ongoing exposure, and changes in body weight. [...]

Nowadays, decision-making is highly challenging in the alignment of decisions to support the success of plant performance and business goals. In this sense, enterprises comprise several functions which interact with each other, such as production, marketing, sales, human resources, logistics, safety and environment. Therefore, it is important to provide systems capable of representing and considering the different elements involved in the enterprise decision making task. In this area, knowledge management technologies have proved to be highly promising for improving information sharing and communication, enhancing the enterprise operation. The industrial waste management stands for an end-of-pipe problem involving gas, liquid or solid effluents which contain contaminants originated from industrial activities. Waste streams must meet discharge constraints imposed by environmental regulations before being disposed of in the environment. Thus, waste treatment plants comprise several technologies, and treatment allocation decisions are usually taken based on company-specific selection criteria. Therefore, there is a large amount of data and information which has to be collected and organized, and the choice of the adequate option for an entire manufacturing site with hundreds of continuously changing effluents becomes an overwhelming task. The use of an ontological model for representing a waste treatment plant has been detected as an opportunity for providing decision makers with new technologies to assess and evaluate the plant performance using information quality. This work aims at improving the information management based on a semantic representation of a waste treatment plant, namely its operational and logistics functions. As a result, more accurate information is provided to the optimization tools which will lead to better solutions based on the plant constraints.

BACKGROUND: Human milk and blood are monitored to detect time trends of persistent organic pollutants (POPs) in humans. It is current practice to use log-linear regression to fit time series [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jpubeco.2008.11.002 Byline: Mathias Hungerbuhler (a), Etienne Lehmann (b) Keywords: Optimal taxation; Minimum wage; Search-matching unemployment; Bunching; Wage bargaining Abstract: We build a theoretical model to study whether a minimum wage can be welfare-improving if it is implemented in conjunction with an optimized nonlinear income tax. We consider this issue in a framework where search frictions on the labor market generate unemployment. Workers differ in productivity. The government does not observe workers' productivity but only their wages. Hence, the redistributive policy solves an adverse selection problem. We show that a minimum wage is optimal if the bargaining power of the workers is relatively low. However, if the government controls the bargaining power, then it is preferable to set a sufficiently high bargaining power. Author Affiliation: (a) University of Namur, Belgium (b) CREST, IZA and IDEP, France Article History: Received 26 July 2007; Revised 15 September 2008; Accepted 14 November 2008 Article Note: (footnote) [star] We thank seminar participants at ERMES-Paris 2, CREST, CORE, the PET 2007 meeting in Nashville and the T2M 2008 meeting in Cergy. In particular, we thank Pierre Cahuc, Guy Laroque, Cyril Nouveau, the editor Pierre Pestieau and two anonymous referees for fruitful comments. A part of this research was realized while Hungerbuhler was visiting ERMES-Paris 2 and another part while Lehmann was visiting the Department of Economics of the Universite Catholique de Louvain.

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1467-937X.2006.00394.x Byline: MATHIAS HUNGERBUHLER (a), ETIENNE LEHMANN (b), ALEXIS PARMENTIER (c), BRUNO VAN DER LINDEN (d) Abstract: This paper characterizes optimal non-linear income taxation in an economy with a continuum of unobservable productivity levels and endogenous involuntary unemployment due to frictions in the labour markets. Redistributive taxation distorts labour demand and wages. Compared to their efficient values, gross wages, unemployment, and participation are lower. Average tax rates are increasing. Marginal tax rates are positive, even at the top. Finally, numerical simulations suggest that redistribution is much more important in our setting than in a comparable Mirrlees-type setting. Author Affiliation: (a)University of Namur (b)ERMES, Universite Catholique de Louvain, and IZA (c)Universite Catholique de Louvain, EUREQua, and ERMES (d)Universite Catholique de Louvain, FNRS, IZA, and ERMES Article History: First version received December 2003; final version accepted November 2005 (Eds.)

The present paper reviews Tertiary volcanic and sedimentary formations in the Inter-Andean region of southern Ecuador (between 2 [degrees] S and 4 [degrees] 20'S) in order to develop a geodynamic model of the region. The formations occur in the southern shallow prolongation of the Inter-Andean Valley between the Cordillera Real to the east, and the Cordillera Occidental and Amotape-Tahuin Provinces to the west. One hundred fifty zircon fission-track analyses has established a detailed chronostratigraphy for the sedimentary and volcanic formations and several small intrusions. The Paleogene to early Miocene formations are dominated by intermediate and acidic volcanic and pyroclastic rocks. In addition, relics of Eocene continental sedimentary series have been identified. The Neogene sedimentary series lie unconformably on deformed and eroded metamorphic, sedimentary and volcanic formations. They were deposited in two stages, which are separated by a major unconformity dated at [approximately equal to] 10-9 Ma. (1) During the middle and early late Miocene ([approximately equal to] 15-10 Ma) marginal marine deltaic, lagoonal, lacustrine and fluvial environments prevailed, which we group under the heading 'Pacific Coastal sequences'. They presumably covered a greater surface area in southern Ecuador than their present occurrence in small topographic depressions. We suggest that they were deposited in the shallow marine Cuenca and Loja Embayments. Deposition in a marginal marine environment is also supported by the occurrence of brackish water ostracods and other fauna. (2) Above the regional (angular) unconformity, the coastal facies are overlain by late Miocene ([approximately equal to] 9-5 Ma) continental alluvial fan and fluvial facies which are in turn covered by mainly airborne volcanic material. They represent the 'Intermontane sequences' of the basins of Cuenca, Giron-Santa Isabel, Nabon, Loja and Malacatos-Vilcabamba. Sedimentologic and stratigraphic results are used to discuss the tectonic setting of Neogene sedimentation in the forearc and arc domain of the Ecuadorian subduction system. During the Pacific Coastal stage, northward displacement of the coastal forearc block along the Calacali-Pallatanga fault zone has driven crustal collapse in the Inter-Andean region. As a result, extensional subsidence drove the eastward ingression of shallow seas into the Cuenca and Loja Embayments from the Manabi and Progreso Basins to the west. Tectonic inversion in the forearc area during the early late Miocene (at [approximately equal to] 9.5 Ma) reflects the initiation of W-E oriented compression and uplift in the Inter-Andean region and the establishment of smaller Intermontane stage basins, which host the continental sequences. Coeval topographic rise of the Cordillera Occidental is indicated by the onset of clastic input from the west. The small Intermontane Basin of Nabon ([approximately equal to] 8.5-7.9 Ma) formed during the period of maximum compression. The present data prove that the Neogene Andean forearc and arc area in southern Ecuador was a site of important but variable tectonic activity, which was presumably driven by the collision and coupling of the Carnegie Ridge with the Ecuadorian margin since [approximately equal to] 15-9 Ma. Keywords: sedimentary facies; volcanics; fission-track chronostratigraphy; Neogene tectonics

Researchers from the Swiss Federal Institute of Technology presented a method to calculate the persistence of parent compounds such as methyl tert-butyl ether (MTBE) and atrazine and its byproducts tert-butyl alcohol and desisopropyl atrazine (DIA).

Introduction The Stockholm Convention on Persistent Organic Pollutants (POPs) entered into force in 2004 and aims to protect humans and the environment from POPs (Stockholm Convention on Persistent Organic Pollutants [...], BACKGROUND: Biomonitoring data of persistent organic pollutants (POPs) in breast milk are increasingly collected and available for quantitative analysis of levels and time trends. A common approach is to apply log-linear regression to calculate doubling and halving times of the POP concentrations based on the temporal trend observed in breast milk. However, there are different, sometimes conflicting interpretations of these doubling and halving times. OBJECTIVES: We provide a mechanistic understanding of doubling and halving times where possible. Five recommendations are proposed for dealing with POP concentration trends in breast milk during three distinct periods (pre-ban, transition, post-ban period). DISCUSSION: Using temporal trends of BDE-47 and PCB-153 in breast milk data, we show which information can be gained from the time-trend data. To this end, we analyzed time trends of hypothetical POPs for different periods with time-variant exposure and different intrinsic elimination half-lives, using a dynamic population-based pharmacokinetic model. Different pieces of information can be extracted from time-trend data from different periods. The analysis of trends of short-lived POPs is rather straightforward and facilitates extraction of the intrinsic elimination half-lives from the breast milk data. However, trends of slowly eliminated POPs only provide indications for the exposure time trend. CONCLUSIONS: Time-trend data of rapidly eliminated POPs provide information on exposure time trends and elimination half-lives. Temporal trends of slowly eliminated POPs are more complicated to interpret, and the extraction of exposure time trends and elimination half-lives require data sets covering several decades. http://dx.doi.org/10.1289/ehp.1510219.

Pulse radiolysis and electrochemistry in aqueous solution and at different acidity conditions were done to study the geometry changes that accompany the redox chemistry of (Cu1(TTCN)2). It was found that the changes are dependent on the lability of TTCN monodentate and on pH conditions. The geometry changes were observed in alkaline conditions in which the initial copper(I) complex occurs in a partially hydrolyzed form. The pH also dictates the occurrence of protonation of (CuII(TTCN-kappa3)(H2O)3)2+, the intermediate precursor of (CuII(TTCN-kappa3)2)2+.

Owing to increasing rates of hypertension and cardiovascular-related diseases in developing countries, compliance with antihypertensive medication is of major public health importance. Few studies have reported on compliance in developing countries. We determined the compliance of 187 patients with uncontrolled hypertension in the Seychelles (Indian Ocean), by assessing the presence of a biologic marker (riboflavin) in the urine. The urine tested positive in 56% of the cases. Compliance varied from one physician to another (highest 72% versus lowest 33%, P = 0.003), improved with the level of literacy (62% versus 45%, P = 0.024), and depended on the presence or absence of diuretics in the medication (respectively, 45% versus 66%, P = 0.005). The ability of patients to report correctly the number of antihypertensive pills to be taken daily was a predictor of compliance (62% of the patients who gave appropriate answers had positive urine for the marker versus 31% for those giving inappropriate answers)., Introduction Treatment of hypertension has been shown to reduce cardiovascular morbidity and mortality[1, 2]. Uncontrolled hypertension has been attributed to patients' failure to follow properly a prescribed drug regimen in [...]

Introduction At present, there are comprehensive empirical data sets showing the levels of legacy persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT), in human tissue. In [...], BACKGROUND: Population pharmacokinetic models combined with multiple sets of age--concentration biomonitoring data facilitate back-calculation of chemical uptake rates from biomonitoring data. OBJECTIVES: we back-calculated uptake rates of PBDEs for the Australian population from multiple biomonitoring surveys (top-down) and compared them with uptake rates calculated from dietary intake estimates of PBDEs and PBDE concentrations in dust (bottom-up). METHODS: Using three sets of PBDE elimination half-lives, we applied a population pharmacokinetic model to the PBDE biomonitoring data measured between 2002-2003 and 2010-2011 to derive the top-down uptake rates of four key PBDE congeners and six age groups. For the bottom-up approach, we used PBDE concentrations measured around 2005. RESULTS: Top-down uptake rates of [[summation].sub.4] BDE (the sum of BDEs 47, 99, 100, and 153) varied from 7.9 to 19 ng/kg/day for toddlers and from 1.2 to 3.0 ng/kg/day for adults; in most cases, they were--for all age groups--higher than the bottom-up uptake rates. The discrepancy was largest for toddlers with factors up to 7-15 depending on the congener. Despite different elimination half-lives of the four congeners, the age-concentration trends showed no increase in concentration with age and were similar for all congeners. CONCLUSIONS: In the bottom-up approach, PBDE uptake is underestimated; currently known pathways are not sufficient to explain measured PBDE concentrations, especially in young children. Although PBDE exposure of toddlers has declined in the past years, pre- and postnatal exposure to PBDEs has remained almost constant because the mothers' PBDE body burden has not yet decreased substantially. http://dx.doi.org/10.1289/ehp.1408960

Introduction Bisphenol A (BPA) is a high production-volume chemical and is used in many consumer products, such as polycarbonate plastics, epoxy resins, and thermal paper (Vandenberg et al. 2007). BPA [...], BACKGROUND: The endocrine disrupting chemical bisphenol A (BPA) has been facing stricter regulations in recent years. BPA analogs, such as the bisphenols S, F, and AF (BPS, BPF, and BPAF) are increasingly used as replacement chemicals, although they were found to exert estrogenic effects similar to those of BPA. Research has shown that only the parent compounds have affinity to the estrogen receptors, suggesting that the pharmacokinetic behavior of bisphenols (BPs) can influence their potency. OBJECTIVES: Our goal was to compare the pharmacokinetic behaviors of BPA, BPS, BPF, and BPAF for different age groups after environmentally relevant external exposures by taking into account substance-specific metabolism kinetics and partitioning behavior. This comparison allowed us to investigate the consequences of replacing BPA with other BPs. METHODS: We readjusted a physiologically based pharmacokinetic (PBPK) model for peroral exposure to BPA and extended it to include dermal exposure. We experimentally assessed hepatic and intestinal glucuronidation kinetics of BPS, BPF, and BPAF to parametrize the model for these BPs and calibrated the BPS model with a biomonitoring study. We used the PBPK models to compare resulting internal exposures and focused on females of childbearing age in a two-dimensional Monte Carlo uncertainty analysis. RESULTS: Within environmentally relevant concentration ranges, BPAF and BPS were glucuronized at highest and lowest rates, respectively, in the intestine and the liver. The predominant routes of BPS and BPAF exposure were peroral and dermal exposure, respectively. The calibration of the BPS model with measured concentrations showed that enterohepatic recirculation may be important. Assuming equal external exposures, BPS exposure led to the highest internal concentrations of unconjugated BPs. CONCLUSIONS: Our data suggest that the replacement of BPA with structural analogs may not lower the risk for endocrine disruption. Exposure to both BPS and BPAF might be more critical than BPA exposure, if their respective estrogenic potencies are taken into account.

Let G be a finite plane multigraph and G' its dual. Each edge e of G is interpreted as a resistor of resistance Re, and the dual edge e' is assigned the dual resistance Re':=1/Re. Then the equivalent resistance re over e and the equivalent resistance re' over e' satisfy re/Re+re'/Re'=1. We provide a graph theoretic proof of this relation by expressing the resistances in terms of sums of weights of spanning trees in G and G' respectively. [ABSTRACT FROM AUTHOR]