55 research outputs found

    Estimating the impact of immigration on housing prices and housing affordability in New Zealand

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    This research examines the response of New Zealand housing markets to immigration shocks. The effects of migrants in general have been widely debated in New Zealand, and have been the focus of many studies around the world. This research focuses solely on the impact of migration on the issue of housing, the largest component of peoples’ wealth. Drawing on housing, migration and census data between the years 1996 to 2011, the regression analysis in this study reveals that there was a positive correlation between external migration shocks and house prices. A 1% migration shock increased house prices by approximately 7.5% on a national scale. Furthermore, it is found that smaller housing markets are less able to ‘cope’ with housing pressure exerted by migrants, compared to bigger cities where migrants tend to cluster. This research suggests that the possible existence of supply constraints in the New Zealand housing market, whereby the market is unable to adjust to a sudden inflow of overseas migrants

    Lead adsorption behaviours on nanoscale zero valent irons (nZVI) coupled with rice husk MCM-41

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    The aims of this work were to investigate the characteristics of nanoscale zero valent irons (nZVI) coupled with mesoporous materials (RH-MCM-41) adsorbent and to study the removal mechanisms of Pb (II) from synthetical solutions using full pictorial design batch experiments. Synthetic nZVI coupled with RH MCM-41 as Pb (II) adsorbent were characterized by XRD, TEM, BET and XANES. The results of XANES analyses confirmed the ability of RH-MCM-41 to prevent oxidations of Fe0 to Fe2+ and Fe3+. XANES results also verified the oxidation states of Pb (II). The solution pH was the most significant positive effect in controlling Pb (II) adsorption. The equilibrium and kinetic adsorption isotherms well fitted with the Langmuir isotherm. The pseudo-second order kinetic adsorption indicated that the adsorption process is the rate limiting step for Pb (II) removal. Furthermore, Langmuir-Hinshelwood confirmed the obvious Pb (II) adsorption at the active site of adsorbents. The reduction rate constant (kr = 5,000 mg/L.min) was higher than the adsorption rate constant (Kad = 0.0002 L/mg). Regarding the research results, four pathways including: reduction process, adsorption on FeOOH, adsorption on RH-MCM-41 and complex reaction between Fe and Pb ions were suggested for Pb (II) removal by nZVI coupled with RH-MCM-41

    Toxic metals in toenails as biomarkers of exposure: A review

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    This work was supported by FIS grants PI12/00150, PI17CIII/00034, PI18/00287 (Instituto de Salud Carlos III, State Secretary of R + D + I and European Union (ERDF/ESF, "Investing in your future") ) , P42ES010349 and P30ES009089 (National Institute of Environmental Health Sciences) .Toenails have been used as biomarkers of exposure to toxic metals, but their validity for this purpose is not yet clear and might differ depending on the specific agent. To evaluate this issue, we reviewed the literature on: a) the time-window of exposure reflected by toenails; b) the reproducibility of toenail toxic-metal levels in repeated measures over time; c) their relationship with other biomarkers of exposure, and; d) their association with potential determinants (i.e. sociodemographic, anthropometric, or lifestyle characteristics) or with sources of exposure like diet or environmental pollution. Thus, we performed a systematic review, searching for articles that provided original data for levels of any of the following toxic metals in toenails: aluminum, beryllium, cadmium, chromium, mercury, nickel, lead, thallium and uranium. We identified 88 articles, reporting data from 67 different research projects, which were quite heterogeneous with regard to population profile, sample size and analytical technique. The most commonly studied metal was mercury. Concerning the time-window of exposure explored by toenails, some reports indicate that toenail cadmium, nickel and lead may reflect exposures that occurred 7–12 months before sampling. For repeated samples obtained 1–6 years apart, the range of intraindividual correlation coefficients of aluminum, chromium and mercury was 0.33–0.56. The correlation of toxic metal concentrations between toenails and other matrices was higher for hair and fingernails than for urine or blood. Mercury levels were consistently associated with fish intake, while other toxic metals were occasionally associated with specific sources (e.g. drinking water, place of residence, environmental pollution, and occupation). The most frequently evaluated health endpoints were cardiovascular diseases, cancer, and central nervous system diseases. Available data suggest that toenail mercury levels reflected long-term exposures and showed positive associations with fish intake. The lack of standardization in sample collection, quality control, analytical techniques and procedures – along with the heterogeneity and conflicting results among studies – mean it is still difficult to conclude that toenails are a good biomarker of exposure to toxic metals. Further studies are needed to draw solid conclusions about the suitability of toenails as biomarkers of exposure to toxic metals.FIS (Instituto de Salud Carlos III, State Secretary of R + D + I) PI12/00150 PI17CIII/00034 PI18/00287FIS (European Union (ERDF/ESF, "Investing in your future") PI12/00150 PI17CIII/00034 PI18/00287 United States Department of Health & Human Services National Institutes of Health (NIH) - USA NIH National Institute of Environmental Health Sciences (NIEHS) P42ES010349 P30ES00908

    Barium Promotes Anchorage-Independent Growth and Invasion of Human HaCaT Keratinocytes via Activation of c-SRC Kinase

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    Explosive increases in skin cancers have been reported in more than 36 million patients with arsenicosis caused by drinking arsenic-polluted well water. This study and previous studies showed high levels of barium as well as arsenic in the well water. However, there have been no reports showing a correlation between barium and cancer. In this study, we examined whether barium (BaCl2) may independently have cancer-related effects on human precancerous keratinocytes (HaCaT). Barium (5–50 µM) biologically promoted anchorage-independent growth and invasion of HaCaT cells in vitro. Barium (5 µM) biochemically enhanced activities of c-SRC, FAK, ERK and MT1-MMP molecules, which regulate anchorage-independent growth and/or invasion. A SRC kinase specific inhibitor, protein phosphatase 2 (PP2), blocked barium-mediated promotion of anchorage-independent growth and invasion with decreased c-SRC kinase activity. Barium (2.5–5 µM) also promoted anchorage-independent growth and invasion of fibroblasts (NIH3T3) and immortalized nontumorigenic melanocytes (melan-a), but not transformed cutaneous squamous cell carcinoma (HSC5 and A431) and malignant melanoma (Mel-ret) cells, with activation of c-SRC kinase. Taken together, our biological and biochemical findings newly suggest that the levels of barium shown in drinking well water independently has the cancer-promoting effects on precancerous keratinocytes, fibroblast and melanocytes in vitro

    Toenails as biomarker of exposure to essential trace metals: A review

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    Health problems associated with essential trace metals can result from both inadequate (i.e., low intake) and excessive exposures (i.e., from environmental and/or occupational source). Thus, measuring the exposure level is a real challenge for epidemiologists. Among non-invasive biomarkers that intend to measure long-term exposure to essential trace metals, the toenail is probably the biological matrix with the greatest potential. This systematic review collects the current evidence regarding the validity of toenail clippings as exposure biomarker for trace metals such as boron, cobalt, copper, iron, manganese, molybdenum, selenium, silicon, vanadium and zinc. Special attention was paid to the time-window of exposure reflected by the toenail, the intraindividual variability in exposure levels over time in this matrix, and the relationship of toenail with other biomarkers, personal characteristics and environmental sources. Our search identified 139 papers, with selenium and zinc being the most studied elements. The variability among studies suggests that toenail levels may reflect different degrees of exposure and probably correspond to exposures occurred 3–12 months before sampling (i.e., for manganese/selenium). Few studies assessed the reproducibility of results over time and, for samples obtained 1–6 years apart, the correlation coefficient were between 0.26 and 0.66. Trace metal levels in toenails did not correlate well with those in the blood and urine and showed low-moderate correlation with those in the hair and fingernails.This work was supported by FIS grants PI12/00150, PI17CIII/00034 & PI18/00287 (Instituto de Salud Carlos III, State Secretary of R + D + I and European Union (ERDF/ESF, "Investing in your future"))

    Identifying Optimum Taper Lengths for Zipper Merging Applications using Real Data and Microscopic Simulation

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    Motorists lack of understanding on the proper way to maneuver through lane closures during congested periods cause driver confusion. This confusion directly and indirectly creates inconsistent flow patterns, forced merges, travel time delays, and crashes. Engineers and developers have tried to improve the merge systems used in construction zones to reduce driver frustration, improve travel time, and increase safety. Encouraging drivers to use the zipper merge approach has been assumed by some to target these issues. When implemented, drivers jointly merge together in an alternating fashion at two-to-one lane closures/reductions. There is a difference in opinion between traffic officials concerning the taper length required to efficiently accommodate these types of merging patterns – particularly those that occur near construction sites. Current practice uses the taper design guideline presented in the MUTCD. However, some believe this unique approach to merging at lane reductions should be accompanied by a shorter/longer taper. This study simulated 192 scenarios consisting of eight different percent truck compositions, six different transition lengths, and four different traffic volumes in VISSIM. The simulation models were calibrated with field data taken while a zipper merge configuration was in operation on a freeway. The main objective was to identify the optimum transition length when placing a zipper merge configuration because it visually and physically promoted alternating merging maneuvers. The results indicated none of the six tested taper lengths had a clear advantage over the other under multiple traffic volumes and truck percentages. Although statistically equal, operational differences in response to taper lengths were present and became more pronounced as volumes and truck percentages increased

    Arsenic and Other Metals’ Presence in Biomarkers of Cambodians in Arsenic Contaminated Areas

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    Chemical analyses of metal (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Ba, and Pb) concentrations in hair, nails, and urine of Cambodians in arsenic-contaminated areas who consumed groundwater daily showed elevated levels in these biomarkers for most metals of toxicological interest. The levels of metals in biomarkers corresponded to their levels in groundwater, especially for As, whose concentrations exceeded the WHO guidelines for drinking water. About 75.6% of hair samples from the population in this study contained As levels higher than the normal level in unexposed individuals (1 mg·kg−1). Most of the population (83.3%) showed As urinary levels exceeding the normal (<50 ng·mg−1). These results indicate the possibility of arsenicosis symptoms in residents of the areas studied. Among the three biomarkers tested, hair has shown to be a reliable indicator of metal exposures. The levels of As (r2 = 0.633), Ba (r2 = 0.646), Fe (r2 = 0.595), and Mo (r2 = 0.555) in hair were strongly positively associated with the levels of those metals in groundwater. In addition, significant weak correlations (p < 0.01) were found between levels of exposure to As and As concentrations in both nails (r2 = 0.544) and urine (r2 = 0.243)

    Estimating the impact of immigration on housing prices and housing affordability in New Zealand

    No full text
    This research examines the response of New Zealand housing markets to immigration shocks. The effects of migrants in general have been widely debated in New Zealand, and have been the focus of many studies around the world. This research focuses solely on the impact of migration on the issue of housing, the largest component of peoples’ wealth. Drawing on housing, migration and census data between the years 1996 to 2011, the regression analysis in this study reveals that there was a positive correlation between external migration shocks and house prices. A 1% migration shock increased house prices by approximately 7.5% on a national scale. Furthermore, it is found that smaller housing markets are less able to ‘cope’ with housing pressure exerted by migrants, compared to bigger cities where migrants tend to cluster. This research suggests that the possible existence of supply constraints in the New Zealand housing market, whereby the market is unable to adjust to a sudden inflow of overseas migrants

    THREE ESSAYS ON OPTIMIZATION, MACHINE LEARNING, AND GAME THEORY IN ENERGY

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    This dissertation comprises three main essays that share a common theme: developing methods to promote sustainable and renewable energy from both the supply and demand sides, from an application perspective. The first essay (Chapter 2) addresses demand response (DR) scheduling using dynamic programming (DP) and customer classification. The goal is to analyze and cluster residential households into homogeneous groups based on their electricity load. This allows retail electric providers (REPs) to reduce energy use and financial risks during peak demand periods. Compared to a business-as-usual heuristic, the proposed approach has an average 2.3% improvement in profitability and runs approximately 70 times faster by avoiding the need to run the DR dynamic programming separately for each household. The second essay in Chapter 3 analyzes the integration of renewable energy sources and battery storage in energy systems. It develops a stochastic mixed complementarity problem (MCP) for analyzing oligopolistic generation with battery storage, taking into account both conventional and variable renewable energy supplies. This contribution is novel because it considers multi-stage stochastic MCPs with recourse decisions. The sensitivity analysis shows that increasing battery capacity can reduce price volatility and variance of power generation. However, it has a small impact on carbon emissions reduction. Using a stochastic MCP approach can increase power producers' profits by almost 20 percent, as proposed by the value of stochastic equilibrium solutions. Higher battery storage capacity reduces the uncertainty of the system in all cases related to average delivered prices. Nevertheless, investing in enlarging battery storage has diminishing returns to producers' profits at a certain point restricted by market limitations such as demand and supply or pricing structure. The third essay (Chapter 4) proposes a new practical application of the stochastic dual dynamic programming (SDDP) algorithm that considers uncertainties in the electricity market, such as electricity prices, residential photovoltaic (PV) generation, and loads. The SDDP model optimizes the scheduling of battery storage usage for sequential decision-making over a planning horizon by considering predicted uncertainty scenarios and their associated probabilities. After examining the benefits of shared battery storage in housing companies, the results show that the SDDP model improves the average objective function values (i.e., costs) by approximately 32% compared to a model without it. The results also indicate that the mean objective function values at the end of the first stage of the proposed SDDP model with battery storage and the deterministic LP model equivalent (with perfect foresight) with battery storage differ by less than 30%. The models and insights developed in this dissertation are valuable for facilitating energy policy-making in a rapidly evolving industry. Furthermore, these contributions can advance computational techniques, encourage the use and development of renewable energy sources, and increase public education on energy efficiency and environmental awareness

    Arsenic and Other Metals’ Presence in Biomarkers of Cambodians in Arsenic Contaminated Areas

    No full text
    Chemical analyses of metal (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Ba, and Pb) concentrations in hair, nails, and urine of Cambodians in arsenic-contaminated areas who consumed groundwater daily showed elevated levels in these biomarkers for most metals of toxicological interest. The levels of metals in biomarkers corresponded to their levels in groundwater, especially for As, whose concentrations exceeded the WHO guidelines for drinking water. About 75.6% of hair samples from the population in this study contained As levels higher than the normal level in unexposed individuals (1 mg·kg−1). Most of the population (83.3%) showed As urinary levels exceeding the normal (<50 ng·mg−1). These results indicate the possibility of arsenicosis symptoms in residents of the areas studied. Among the three biomarkers tested, hair has shown to be a reliable indicator of metal exposures. The levels of As (r2 = 0.633), Ba (r2 = 0.646), Fe (r2 = 0.595), and Mo (r2 = 0.555) in hair were strongly positively associated with the levels of those metals in groundwater. In addition, significant weak correlations (p < 0.01) were found between levels of exposure to As and As concentrations in both nails (r2 = 0.544) and urine (r2 = 0.243)
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