Anthropology, tooth wear, and occlusion ab origine

The purpose of this essay is to emphasize that anthropology, the study of man in his environments, is a potent tool for scientific discovery and inspiration in dental science. It attempts to capture flashes of creative anthropological insight which have illuminated studies of tooth wear and occlusion in the past. While it documents contributions, understandings, and misunderstandings from Australian and New Zealand dentists, it is not a hagiography. The real saint of this essay is the Australian aborigine. For when men and women are understood in their environments, much is learned from them which challenges preconceptions of our dental science culture. The essay concludes that new, contemporary Australian culture needs to be studied by anthropological approaches if we are to understand how dental erosion is exacerbating tooth wear and damaging the occlusions of contemporary Australians. Much remains to be discovered about contemporary lifestyles, habits, and diets that lead to dental erosion, the principal cause of contemporary tooth wear in this part of the world.     

Photoconductivity and photovoltaic effect of charge-transfer complex of poly[4-phenyl-2,6-(p-phenoxy) quinoline] and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone

A new polymer containing a heterocyclic quinoline unit in the main chain, poly[4-phenyl-2,6-(p-phenoxy) quinoline] (PQ), was synthesized by an acid-catalyzed self-condensation reaction. We have found that PQ, which is generally a good insulator itself, can show photoconductivity when doped with an electron acceptor. From the UV-VIS absorption spectra, we found that PQ can form a charge-transfer (CT) complex with an electron acceptor, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The CT complex of the PQ-DDQ mixture showed distinct photoconductivity. Employing the DDQ composition ranging from 5 to 10 wt %, the ratio of dark and photoconductivity was calculated to be about 1 : 100 at an applied electric field of 10₅ V/cm. Additionally, the bilayer sample of PQ/DDQ exhibited a significant photovoltaic effect. The photovoltaic current increased with increasing photointensity. The open-circuit voltage was measured ranging from 0.4 to 0.7 V and the photovoltaic conversion efficiency was calculated to be 10^?3?10_?2%. The PQ film treated with DDQ vapor showed a relatively higher photovoltaic effect than that of the sample treated with DDQ solution. © 1993 John Wiley & Sons, Inc.     

Human melanocytes and keratinocytes exposed to UVB or UVA in vivo show comparable levels of thymine dimers

Epidemiology shows a relationship between solar exposure and all types of skin cancer. Understanding the mechanisms of skin cancer requires knowledge of the photomolecular events that occur within the relevant epidermal cell types in vivo. Studies to date have focused on UVR-induced DNA lesions in keratinocytes, the majority epidermal cell population which gives rise to most skin cancers. Malignant melanoma, arising from melanocytes (5%-10% of epidermal cells), accounts for most skin cancer deaths. We report on new techniques to detect DNA photolesions in human epidermal melanocytes in situ. Previously nonexposed buttock skin of volunteers of skin types I/II was exposed to clinically relevant doses of narrow bandwidth UVB (300 nm) and UVA (320 nm, 340 nm, 360 nm) radiation. Biopsies were taken immediately afterwards and processed for routine histology. Microscope sections were prepared and double-stained with fluorescent-tagged monoclonal antibodies for thymine dimers and melanocytes. UVR dose-response curves for dimer levels within melanocyte nuclei were determined by image analysis and compared with dimer levels in adjacent basal cell keratinocytes. Our data show that UVB and UVA readily induce thymine dimers in melanocytes at levels that are comparable with those found in adjacent keratinocytes. This new technique will enable melanocyte specific studies, such as DNA repair kinetics, to be done in vivo.     

CANADIAN HYDROCARBON RESOURCE DEVELOPMENT UP TO THE YEAR 2000

Canada is blessed with numerous large and small sedimentary basins, both onshore and offshore, many of which have hardly been probed for their hydrocarbon potential. Only the most promising aspects of this potential can be highlighted in a brief review such as this, and hence the objectives of the report are (i); to present a regional assessment of the onshore and offshore basins in Canada and to document reservoir units for both conventional and non-conventional hydrocarbon occurrences within the basin fills which may yield significant discoveries in the future (Map 1), and (ii) to emphasize Canada's political-investment environment, and the roles of Petro-Canada, Native Land claims, etc., since most, if not all, of the exploratory targets mentioned require large financial commitments and stable domestic and global conditions.
Previous publications provided essential information to substantiate and/or alter views and projections expressed. Only summary papers are referred to in this review, and we apologize to authors whose views we have used but not acknowledged.     

Alternatives in mental health care and criteria for quality assurance.

The present mental health delivery system is composed largely of hospital services and outpatient office-based services. Alternatives to traditional mental health services have been slow to develop, although their cost-effectiveness is well demonstrated. A major reason for this is that 3rd-party payers are reluctant to reimburse for these services. The present study reviews the development of nontraditional, or alternate, approaches to mental health care and suggest applicable quality assurance strategies. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Procedure for calculating the crystallinity of ethylene–vinyl acetate copolymers and low-density polyethylene as a function of temperature

A method is described for determining the x-ray crystallinity of ethylene–vinyl acetate copolymers at differing temperatures. An equation is derived for the symmetrical curves of crystallinity versus temperature thus obtained, from which the crystallinity at any temperature can be calculated. In order to determine the constants of the equation for a particular polymer, it is only necessary to determine the melting point and per cent crystallinity of the resin at a known temperature. The equation can also be applied to conventional polyethylenes, but not to linear polyethylenes. It is suggested that this is due to the former resins having a broad crystallite size distribution compared with the narrow distribution present in high-density polyethylene.     

Simple technique for the accurate determination of delay-time variations in acoustic-surface-wave structures

A method of determining small variations in delay time of acoustic surface waves is described which is both simple and accurate. As an example, the technique is applied to determining the temperature vanation of delay time of surface waves propagating in the z direction on a y face of lithium niobate.