Current and future water issues in the Oldman River Basin of Alberta, Canada.

Long-term trends in alpine and prairie snow pack accumulation and melt are affecting streamflow within the Oldman River Basin in southern Alberta, Canada. Unchecked rural and urban development also has contributed to changes in water quality, including enhanced microbial populations and increased waterborne pathogen occurrence. In this study we look at changing environment within the Oldman River Basin and its impact on water quality and quantity. The cumulative effects include a decline in net water supplies, and declining quality resulting in increased risk of disease. Our data indicates that decreases in the rate of flow of water can result in sedimentation of bacterial contaminants within the water column. Water for ecosystems, urban consumption, recreation and distribution through irrigation is often drawn from waterholding facilities such as dams and weirs, and concern must be expressed over the potential for contaminate build-up and disproportionate potential of these structures to pose a risk to human and animal health. With disruption of natural flow rates for water resulting from environmental change such as global warming and/or human intervention, increased attention needs to be paid to use of best management practices to protect source water supplies.     

Methacryloxyethyl phosphate‐grafted expanded polytetrafluoroethylene membranes for biomedical applications

Expanded polytetrafluoroethylene (ePTFE) membranes were modified by graft copolymerization with methacryloxyethyl phosphate (MOEP) in methanol and 2‐butanone (methyl ethyl ketone (MEK)) at ambient temperature using gamma irradiation. The effect of dose rate (0.46 and 4.6 kGy h^?1), monomer concentration (1–40 %) and solvent were studied and the modified membranes were characterized by weight increase, X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XPS was used to determine the % degree of surface coverage using the C? F (ePTFE membrane) and the C? C (MOEP graft copolymer) peaks. Grafting yield, as well as surface coverage, were found to increase with increasing monomer concentration and were significantly higher for samples grafted in MEK than in methanol solution. SEM images showed distinctly different surface morphologies for the membranes grafted in methanol (smooth) and MEK (globular), hence indicating phase separation of the homopolymer in MEK. We propose that in our system, the non‐solvent properties of MEK for the homopolymer play a more important role than solvent chain transfer reactions in determining grafting outcomes. Copyright © 2005 Society of Chemical Industry     

DNA methylation and developmental genes in lymphomagenesis--more questions than answers?

There is now considerable evidence suggesting that alterations in the DNA methylating machinery play an important role in tumorigenesis and tumour progression. For example, focal hypermethylation and generalised genomic demethylation are features of many different types of neoplasms. It is thought that tumorigenesis and tumour progression may be caused by hypermethylation induced mutational events and silencing of genes which control cellular proliferation and/or demethylation induced reactivation of genes which may only be required during embryological development. Consequently, we have begun to investigate the role of DNA methylation and developmental genes in malignant lymphoproliferative diseases. Previously, in all cases of non-Hodgkins lymphoma and leukemia studied, we have shown that the myogenic developmental gene Myf-3 is abnormally hypermethylated. In this review we discuss the possible significance of these findings since in vitro studies suggest that Myf-3 may play an important role in control of the cell cycle and therefore lymphomagenesis. In vitro and in vivo evidence suggests that PAX genes may also have oncogenic potential. The PAX family of developmental genes are involved in cellular differentiation, proliferation and cell migration. Expression of PAX3 in particular is associated with cellular mobility. Our previous studies have indicated that alternate regional expression of PAX genes may be controlled by DNA methylation. Therefore, we have proposed that abnormal methylation profiles of PAX3 may be associated with neoplastic transformation and/or metastatic potential. Results thus far reveal that the paired box of PAX3 is abnormally hypermethylated and the homeobox abnormally hypomethylated in lymphomas and leukemias. These new findings are consistent with our postulate and support the idea that inappropriate methylation induced activation or inactivation of developmental genes such as Myf-3 and PAX3 play an important role in lymphomagenesis and disease progression and that inspection of the methylation status of other developmental genes is warranted.     

Why models rather than rules give a better account of propositional reasoning: A reply to Bonatti and to O'Brien, Braine, and Yang.

D. P. O'Brien et al (see record 1995-08272-001) argue that the mental model theory of propositional reasoning is easy to refute, and they report 3 experiments that they believe falsify the theory. In contrast, L. Bonatti (see record 1995-08253-001) argues that the model theory is too flexible to be falsified. It is shown that the experiments by O'Brien et al do not refute the model theory and that Bonatti's claims are ill founded. Formal rule theories of propositional reasoning have 3 major weaknesses in comparison with the model theory: (1) They have no decision procedure; (2) they lack predictive power, providing no account of several robust phenomena (e.g., erroneous conclusions tend to be consistent with the premises); and (3) as a class of theories, they are difficult to refute experimentally. (PsycINFO Database Record (c) 2010 APA, all rights reserved)