An examination of spatial variation in mercury concentrations in otter (Lutra canadensis) in south-central Ontario

Hair samples were collected from otter (Lutra canadensis) trapped in several parts of south-central Ontario, Canada. The concentrations of total Hg in hair were compared with methyl mercury concentrations in liver tissues from the same individuals to determine if hair is a suitable monitoring tissue. Hg in the two tissues was significantly correlated. Hair was used to monitor Hg in 51 individuals from four townships. The concentrations of total Hg in hair ranged from 4 to 20 micrograms/g. No significant variation among the four sample regions existed. Generally the highest concentrations were found in the youngest members of the population. Some possible explanations for the observations are presented.     

Chemical liquid deposition process for microstructure fabrication

Scientists and engineers are currently moving into a new era to develop precise and intelligent mini-structures and microsystems. The study of mini-structures and microsystems is a rapidly growing area of research with a great potential to accomplish useful tasks in numerous applications. In this paper, a new fabrication technology for microstructures based on the chemical liquid deposition (CLD) is presented. This technology is based on the following principles: micro-droplets of a cold (room temperature) solution or liquid reactant are sprayed from a nozzle and make contact with a hot substrate, the droplets will evaporate, decompose, or react, and then the reacted solid products will deposit on the substrate. By controlling the motion of the nozzle and the spray time, a desired 3D microstructure of the deposited material can be formed through a layer-by-layer scanning technique. The working principle, available materials as well as the process control and modeling is discussed and some preliminary results are presented.     

Second derivative methods applied to implicit first- and second-order systems

A wide variety of methods have been proposed for solving implicit second-order systems of differential equations such as arise in structural and mechanical vibration analyses. Here we discuss a class of methods, based on second derivative formulae, some of which have previously been used by Enright.¹ We show them to have desirable analytic and implementation properties. We relate these methods to others recently proposed by Brusa and Nigro and by Serbin, showing that we obtain algorithms which have all the desirable properties of their methods and which can also be extended to classes of practical problems which were not considered by these other authors. Since implicit first-order systems are also important in practice, for example in finite element analyses of heat conduction problems, we demonstrate the efficient implementation of the second derivative formulae in this case too.     

Deletion of the central proline-rich repeat domain results in altered antigenicity and lack of surface expression of the Streptococcus mutans P1 adhesin molecule

Members of the family of surface adhesins of oral streptococci, including P1 of Streptococcus mutans, contain two highly conserved repeat domains, one rich in alanine (A region) and the other rich in proline (P region). To assess the contribution of the P region to the biological properties of P1, an internal deletion in spaP was engineered. In addition, the P region was subcloned and expressed as a fusion partner with the maltose binding protein of Escherichia coli and liberated by digestion with factor Xa. Results of Western blot experiments in which recombinant polypeptides were probed with a panel of 11 monoclonal antibodies indicated that the P region is a necessary component of conformational epitopes within the central portion of P1. Antibodies reactive with the P region were detected in a polyclonal rabbit antiserum generated against whole S. mutans cells but not in two rabbit antisera generated against purified P1 (Mr approximately 185,000), suggesting that this domain is immunogenic on the surface of intact bacteria but not as part of a soluble full-length molecule. Finally, transformation of a spaP-negative mutant with a shuttle vector containing an internally deleted spaP lacking P-region DNA resulted in a complete absence of surface-localized P1 and substantially less P1 in sonicated cells compared to the case for the mutant complemented with the full-length gene. These results suggest that the P region is an integral component contributing to the conformation of the central region of P1 and indicate that its presence is necessary for surface expression of the molecule on S. mutans.     

Rethinking Global-Regulation: world’s law meets artificial intelligence

This article takes a critical look at Machine Translation of legal text, especially global legislation, through the discussion of Global-Regulation, a state of the art online search engine of the world’s legislation in English. Part 2 explains the rationale for an online platform such as Global-Regulation. Part 3 provides a brief account of the history of the development of machine translation, and it describes some of the limits of the use of statistical machine translation for translating legal texts. Part 4 describes Neural Machine Translation (NMT), which is a new generation of machine translation systems. Finally, Parts 5 and 6 outline the ‘big sky’ thoughts on future directions for Global-Regulation.     

Cadmium levels in Ontario moose and deer in relation to soil sensitivity to acid precipitation

This study examines the influence of buffering capacity of the soil on the levels of cadmium in the kidney, liver and muscle of moose and white-tailed deer from nine sampling sites (four buffered and five non-buffered) in Ontario, Canada. Tissues collected from hunter-killed moose and deer during 1984 and 1985 were analysed for cadmium. Tissue from moose in the non-buffered Algonquin Park site (21.9 +/- 1.1 mg/kg wet weight) and the buffered St. Joseph Island site (12.7 +/- 3.2 mg kg-1) had the highest mean levels of kidney cadmium compared with other sites sampled in Ontario. The highest mean levels of kidney cadmium in deer were found in the non-buffered Loring site (15.1 +/- 0.8 mg kg-1) adjacent to Algonquin. From all sites, the level of cadmium was highest in kidney, lower in liver and was often undetectable in muscle. Cadmium level increased with animal age (p less than 0.05). Levels of cadmium in Ontario moose from some regions are comparable to those found in Quebec and Manitoba and are considerably higher than those of Maine and Scandinavia. Levels of cadmium in kidneys and livers of white-tailed deer in parts of Ontario are considerably lower than those in Pennsylvania. As a result of this study, the Ontario Ministry of Natural Resources, in consultation with the Ontario Ministry of Health, has recommended that the public not consume kidneys or livers of Ontario moose and deer.     

Spatial and temporal trends and effects of contaminants in the Canadian Arctic marine ecosystem: a review

Recent studies have added substantially to our knowledge of spatial and temporal trends of persistent organic pollutants and heavy metals in the Canadian Arctic marine ecosystem. This paper reviews the current state of knowledge of contaminants in marine biota in the Canadian Arctic and where possible, discusses biological effects. The geographic coverage of information on contaminants such as persistent organochlorines (OCs) (PCBs, DDT- and chlordane-related compounds, hexachlorocyclohexanes, toxaphene) and heavy metals (mercury, selenium, cadmium, lead) in tissues of marine mammal and sea birds is relatively complete. All major beluga, ringed seal and polar bear stocks along with several major sea bird colonies have been sampled and analysed for OC and heavy metal contaminants. Studies on contaminants in walrus are limited to Foxe Basin and northern Québec stocks, while migratory harp seals have only been studied recently at one location. Contaminant measurements in bearded seal, harbour seal, bowhead whale and killer whale tissues from the Canadian Arctic are very limited or non-existent. Many of the temporal trend data for contaminants in Canadian Arctic biota are confounded by changes in analytical methodology, as well as by variability due to age/size, or to dietary and population shifts. Despite this, studies of OCs in ringed seal blubber at Holman Island and in sea birds at Prince Leopold Island in Lancaster Sound show declining concentrations of PCBs and DDT-related compounds from the 1970s to 1980s then a levelling off during the 1980s and early 1990s. For other OCs, such as chlordane, HCH and toxaphene, limited data for the 1980s to early 1990s suggests few significant declines in concentrations in marine mammals or sea birds. Temporal trend studies of heavy metals in ringed seals and beluga found higher mean concentrations of mercury in more recent (1993/1994) samples than in earlier collections (1981–1984 in eastern Arctic, 1972–1973 in western Arctic) for both species. Rates of accumulation of mercury are also higher in present day animals than 10–20 years ago. Cadmium concentrations in the same animals (eastern Arctic only) showed no change over a 10-year period. No temporal trend data are available for metals in sea birds or polar bears. There have been major advances in knowledge of specific biomarkers in Canadian Arctic biota over the past few years. The species with the most significant risk of exposure to PCBs and OC pesticides may be the polar bear which, based on comparison with EROD activity in other marine mammals (beluga, ringed seal), appears to have elevated CYP1A-mediated activity. The MFO enzyme data for polar bear, beluga and seals suggest that even the relatively low levels of contaminants present in Arctic animals may not be without biological effects, especially during years of poor feeding.     

Automated estimation of white Gaussian noise level in a spectrum with or without spike noise using a spectral shifting technique

Various tasks, for example, the determination of signal-to-noise ratios, require the estimation of noise levels in a spectrum. This is generally accomplished by calculating the standard deviation of manually chosen points in a region of the spectrum that has a flat baseline and is otherwise devoid of artifacts and signal peaks. However, an automated procedure has the advantage of being faster and operator-independent. In principle, automated noise estimation in a single spectrum can be carried out by taking that spectrum, shifting a copy thereof by one channel, and subtracting the shifted spectrum from the original spectrum. This leads to an addition of independent noise and a reduction of slowly varying features such as baselines and signal peaks; hence, noise can be more readily determined from the difference spectrum. We demonstrate this technique and a spike-discrimination variant on white Gaussian noise, in the presence and absence of spike noise, and show that highly accurate results can be obtained on a series of simulated Raman spectra and consistent results obtained on real-world Raman spectra. Furthermore, the method can be easily adapted to accommodate heteroscedastic noise.