Consumption of bottled water is increasing worldwide. Prior research shows many consumers believe bottled water is convenient and has better taste than tap water, despite reports of a number of water quality incidents with bottled water. The authors explore the demographic and social factors associated with bottled water users in the U.S. and the relationship between bottled water use and perceptions of the quality of local water supply. They find that U.S. consumers are more likely to report bottled water as their primary drinking water source when they perceive that drinking water is not safe. Furthermore, those who give lower ratings to the quality of their ground water are more likely to regularly purchase bottle water for drinking and use bottle water as their primary drinking water source.

Abstract:The recent release of worldwide SRTM 1 DEM and AW3D30 adds new members to the open global medium resolution (90-30 m ground spacing) digital elevation models. Together with the previously existing SRTM 3 and ASTER GDEM, their quality is of great interest to various scientific applications. This paper uses 1:50,000 DEM in Hubei Province of China as a reference to assess their vertical accuracy in terms of terrain types, slopes, and land cover. For ASTER GDEM and AW3D30, we further evaluate their accuracy in terms of the stack number, i.e., the number of scenes used to generate the DEM. It is found out that: (1) all of the DEMs have nearly the same horizontal offset due to the adoption of different datums; (2) the vertical accuracy varies in terms of terrain complexity, from~5 m for plains,~10 m for hills to~20 m for mountains; (3) the vertical accuracy is negatively related to the tangent of terrain slope exponentially in forest areas and linearly in cultivated lands; (4) forest areas have the lowest vertical accuracy, comparing to built-up areas, wetland, and cultivate land areas while SRTM 1 and AW3D30 have the highest accuracy in all land cover classes; (5) the large elevation differences over forest areas are likely due to canopy coverage; and (6) for ASTER GDEM and AW3D30, their accuracy is in general positively related to the stack number. This study provides a practically useful quality specification and comprehensive understanding for these four global DEMs, especially the recently released worldwide SRTM 1 DEM and AW3D30.

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Porcine circovirus type 2 (PCV2) is the primary cause of porcine circovirus disease, and ochratoxin A (OTA)-induced oxidative stress promotes PCV2 replication. In humans, selenoprotein S (SelS) has antioxidant ability, but it is unclear whether SelS affects viral infection. Here, we stably transfected PK15 cells with pig pCDNA3.1-SelS to overexpress SelS. Selenium (Se) at 2 or 4 μM and SelS overexpression blocked the OTA-induced increases of PCV2 DNA copy number and infected cell numbers. SelS overexpression also increased glutathione (GSH), NF-E2-related factor 2 (Nrf2) mRNA, and γ-glutamyl-cysteine synthetase mRNA levels; decreased reactive oxygen species (ROS) levels; and inhibited p38 phosphorylation in PCV2-infected PK15 cells, regardless of OTA treatment. Buthionine sulfoximine reversed all of the above SelS-induced changes. siRNA-mediated SelS knockdown decreased Nrf2 mRNA and GSH levels, increased ROS levels, and promoted PCV2 replication in OTA-treated PK15 cells. These data indicate that pig SelS blocks OTA-induced promotion of PCV2 replication by inhibiting the oxidative stress and p38 phosphorylation in PK15 cells.

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This study suggests that PCV2 infection induces oxidative stress and that intracellular redox status influences PCV2 replication in PK15 cells.