SPATIAL ANALYSIS OF EXPOSURE TO SOIL HEAVY METALS, ORAL BIOACCESSIBILITY AND RISK ASSESSMENT IN HOUSTON, TEXAS

Chronic exposure to heavy metals could lead to adverse health effects such as cancer, neurological development diseases and immunological diseases. The ingestion pathway has been considered the major exposure route for heavy metal contaminated soils. Heavy metals may be proportionally bioaccessible for the human body to absorb. There are no risk assessment studies done in Houston to evaluate health risks from exposure to heavy metals and no spatial analysis done yet. The aims of this dissertation are (1) to characterize 13 heavy metals: magnesium (Mg), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), lead (Pb), barium (Ba), and cadmium (Cd) in soils in Houston, Texas (TX), and evaluate spatial distribution maps of these metals; (2) to assess bioaccessibility of 13 metals (Pb, Cd, Cu, As, Cr, Zn, Ni, Mn, Ba, Co, Mg, Fe, and V) in soils; (3) to estimate human health risks of 10 toxic metals (As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, Zn, and V) using metal concentrations in soils and bioaccessibility concentrations, and to simulate cancer and non-cancer risks maps. We sampled top soils at 96 locations in Houston, TX. We used microwaved-acid digestion system to prepare the soil samples and analyzed metal concentrations in soils by inductively coupled plasma mass spectrometry. Besides, we obtained Environmental Justice Screening and Mapping Tool Indexes to identify possible high exposure groups and emission sources of metals. We simulated heavy metal distribution by ordinary kriging in SAS software and ArcGIS software. Moreover, we used an in-vitro bioaccessibility method to obtain percent bioaccessibility fractions (%BAF) in gastric phase and gastro-intestinal phase. We assessed human health risks by using metal concentrations in soils and bioaccessibility results among five age groups, 0 to \u3c 1 year old (infants), 1 to \u3c 6 year old (toddlers), 6 to \u3c 12 years old (children), 12 to \u3c 18 years old (teenagers), and 18 to \u3c 78 years old (adults), and estimated hazard index (HI) and cancer risks with SAS software and ArcGIS software for non-sampled area. Ninety-six percent of samples had either one or more than one metal over Texas Commission on Environmental Quality (TCEQ) background values. Pb and Zn had more than 80% of samples over TCEQ background levels. We found that closer proximity to National Priority sites and Risk Management Plan sites had higher Ni, Cr, Ba, Cu, Pb and Zn in soils than further proximity. We also discovered environmental justice issues in Houston as minority and low income groups live in neighborhoods with high Ni, Cr, Ba, Cu, and Zn concentrations in soils. We found that most of the metals had decreasing %BAF from gastric phase to gastro-intestinal phase, except Cu and V. The %BAF in gastric phase ranged from 1.22 % to 69.71 %. The %BAF in gastro-intestinal phase ranged from 0.22 % to 45.87%. For chronic non-cancer health effects, all hazard indexes among 5 age groups were under one (1). The infants group had the highest HI followed by toddlers group. Pb contributing 90% and As contributing 6% in HI when applying all three experimental results. Adults group’s cancer risks were 1.02 in a million followed by toddlers group. We suggested that future metal pollution studies interested to point sources in Houston should focus in East and South side. Other studies interested to traffic volume should have better study design to differentiate emission since Houston doesn’t have zoning between industrial area and residential area. Furthermore, for exposure of young children, future studies should focus for soils in playgrounds, parks, or schools, especially around old downtown areas

Using Social Media for Teaching and Learning Understanding Students’ Perceptions of Facebook Use in The Classroom

According to GlobalWebIndex, Facebook topped the list as the most used social media site, followed by Google+, YouTube, and Twitter. Despite the mounting popularity of Facebook among college students, little is known about students’ perception and willingness to adopt Facebook for educational purposes. Drawing on the Theory of Planned Behavior (TPB), the objective of this study is to develop and empirically validate a model that predicts students’ intention to use Facebook in the classroom. In addition, this study aims to extend the model of TPB by incorporating peer communication factors. To this end, an online survey with a sample of 300 undergraduate students will be carried out. This study contributes to our understanding of the educational uses of Facebook among college students in the classroom

Two-sided equivalence on the special linear group

AbstractWe give a canonical form for the double cosets of Γ = SL(r + s, Z) with respect to the congruence subgroup Γ0(n; r, s) with r = s, and determine the number of the double cosets

Rethinking the educational role of school librarians

Conference theme: The Educational Role of School Libraries in the M Generation論壇主題: 學校圖書館在M世代的教育角色This study examined the educational role of school librarians in Hong Kong, Taiwan and Mainland China, and investigated their qualification and professional development respectively. Questionnaires were sent to public primary school librarians in these three regions on a convenience-sampling basis, 28 responses were received from Hong Kong, 15 from Taiwan and 14 from Mainland China. The result indicated that the educational role of school librarians in Hong Kong and Taiwan were realized to a higher extent than that of school librarians in Mainland China in developing students’ information literacy, fostering students’ reading ability and collaborating with teachers. However, there was still some disparity of the educational role of school librarians in Hong Kong and Taiwan.postprin

Mementos and the Endowment Effect

This research provides evidence for a new moderator of the endowment effect: having a memento of the endowed object. Three studies adapting classic endowment effect paradigms and using a variety of endowment objects and mementos demonstrate that having a memento of an endowment increases willingness to trade the endowment and decreases selling prices for the endowment. We provide evidence that mementos attenuate the endowment effect regardless of whether the memento is a separate small gain when facing the loss of the endowment or a small part of the original endowment that is kept. Examining mementos in context of the endowment effect not only provides insight into the psychology underlying the reluctance to part with one\u27s endowment but also other consumer disposition behaviors

The Magnification Invariant of Circularly-symmetric Lens Models

In the context of strong gravitational lensing, the magnification of image is of crucial importance to constrain various lens models. For several commonly used quadruple lens models, the magnification invariants, defined as the sum of the signed magnifications of images, have been analytically derived when the image multiplicity is a maximum. In this paper, we further study the magnification of several disk lens models, including (a) exponential disk lens, (b) Gaussian disk lens, (c) modified Hubble profile lens, and another two of the popular three-dimensional symmetrical lens model, (d) NFW lens and (e) Einasto lens. We find that magnification invariant does also exist for each lens model. Moreover, our results show that magnification invariants can be significantly changed by the characteristic surface mass density $\kappa_{\rm c}$.Comment: 14 pages, 6 figures. Accepted for publication in RA