A5012502218- Climate change and permafrost
- Cryospheric studies and observations
- Arctic and Antarctic ice dynamics
- Oral microbiology and periodontitis research
- Geology and Paleoclimatology Research
- Hydrology and Watershed Management Studies
- Landslides and related hazards
- Plant Water Relations and Carbon Dynamics
- Dental Health and Care Utilization
- Soil Moisture and Remote Sensing
- Salivary Gland Disorders and Functions
- Bacterial biofilms and quorum sensing
- Winter Sports Injuries and Performance
- Endodontics and Root Canal Treatments
- Climate variability and models
- Remote Sensing and LiDAR Applications
- American Constitutional Law and Politics
- Probiotics and Fermented Foods
- Dental Erosion and Treatment
- Atmospheric and Environmental Gas Dynamics
- Peatlands and Wetlands Ecology
- Smart Materials for Construction
- Dental Research and COVID-19
- Tree-ring climate responses
- Geological Studies and Exploration
Wilfrid Laurier University
2016-2025
University of Waterloo
2021
University of Leeds
2001-2019
St James's University Hospital
2017
Wellcome Trust
2017
Environment and Climate Change Canada
2002-2014
Miami University
1946-2012
Jarvis Christian College
2012
California Institute of Technology
2012
Leeds Dental Hospital
1999-2010
Dental diseases are among the most prevalent and costly affecting industrialized societies, yet highly preventable. The microflora of dental plaque biofilms from diseased sites is distinct that found in health, although putative pathogens can often be detected low numbers at normal sites. In caries, there a shift towards community dominance by acidogenic acid-tolerant Gram-positive bacteria (e.g. mutans streptococci lactobacilli) expense acid-sensitive species associated with sound enamel....
Region 2 comprises arctic and subarctic North America is underlain by continuous or discontinuous permafrost. Its freshwater systems are dominated a low energy environment cold region processes. Central northern areas almost totally influenced air masses while Pacific becomes more prominent in the west, Atlantic east southern at lower latitudes. Air mass changes will play an important role precipitation associated with climate warming. The snow season prolonged resulting long-term storage of...
Observations indicate that over the past several decades, geomorphic processes in Arctic have been changing or intensifying. Coastal erosion, which currently supplies most of sediment and carbon to Ocean [ Rachold et al. , 2000], may doubled since 1955 Mars Houseknecht 2007]. Further inland, expansion channel networks Toniolo 2009] increased river bank erosion Costard 2007] attributed warming. Lakes, ponds, wetlands appear be more dynamic, growing some areas, shrinking others, distribution...
In a naturally stratified snow cover the movement of meltwater into dry is complicated by interaction wetting front with stratigraphic horizons. Field observations showed that when reached premelt horizons, water ponded at interface and then flow fingers developed penetrated lower stratum. The flux in these fingers, which was increased to about twice surface flux, used feed impeding horizons where it froze form ice layers. These layers were major source latent heat released within cover,...
Bacteroides gingivalis W50 was grown in a chemostat under steady-state conditions at pH 7.5 +/- 0.2 and constant growth rate of 6.9 h for periods up to 6 weeks (146 bacterial generations) complex medium. Hemin capable limiting the cells concentration approximately 0.5 micrograms/ml since higher concentrations hemin did not increase cell yields; grew absence exogenously added vitamin K1. Only limited number amino acids metabolized during growth, but because none these totally depleted,...
The first direct measurements of evaporation from a large high‐latitude lake, Great Slave Lake, Northwest Territories, Canada, were made using eddy covariance between July 24 and September 10, 1997, June 22 26, 1998. main body the lake was ice‐free 20 December 13, 1, 1998, January 8, 1999, with extended season in 1997–1998 coinciding 4°C above normal air temperatures an abnormally strong El Niño. Measurements extending roughly 5.0 to 8.5 km across small rock outcrop located near lake....
Abstract The permafrost of the Western Canadian Arctic has a very high ground ice content. As result, vast number thaw lakes in this area are sensitive to changing climate. With prone either increases due thermokarst processes, or complete drainage less than one day melting channels through ice‐rich permafrost. After lake drains, it leaves topographic basin that is often termed Drained Thaw Lake Basin (DTLB). An analysis aerial photographs and maps showed 41 drained study between 1950 2000,...
Over one-third of the global land area undergoes a seasonal transition between predominantly frozen and non-frozen conditions each year, with surface freeze/thaw (FT) state significant control on hydrological biospheric processes over northern areas at high elevations. The NASA Soil Moisture Active Passive (SMAP) mission produced daily landscape FT product 3-km spatial resolution derived from ascending descending orbits SMAP high-resolution L-band (1.4 GHz) radar measurements. Following...
Abstract Snow accumulation and melt were observed at shrub tundra sites in the western Canadian Arctic. End of winter snow water equivalent (SWE) was higher site than site, but lower total snowfall because removed by blowing snow, a component also lost to sublimation. Removal from larger expected shrubs bent over covered during much winter. Although SWE disappeared similar time both sites, suggesting enhanced site. The Land Surface Scheme (CLASS) used explore processes controlling this melt....
The overall spatial and temporal influence of shrub expansion on permafrost is largely unknown due to uncertainty in estimating the magnitude many counteracting processes. For example, shrubs shade ground during snow-free season, which can reduce active layer thickness. At same time, advance timing snowmelt when they protrude through snow surface, thereby exposing thawing earlier spring. Here, we compare 3056 situ frost table depth measurements split between mineral earth hummocks organic...
Abstract. Connections between vegetation and soil thermal dynamics are critical for estimating the vulnerability of permafrost to thaw with continued climate warming changes. The interplay complex biophysical processes results in a highly heterogeneous temperature distribution on small spatial scales. Moreover, link topsoil active layer thickness remains poorly constrained. Sixty-eight loggers were installed at 1–3 cm depth record temperatures Trail Valley Creek study site northwestern...
Abstract. Topography and vegetation play a major role in sub-pixel variability of Arctic snowpack properties but are not considered current passive microwave (PMW) satellite SWE retrievals. Simulation snow is also problematic when downscaling climate models. In this study, we simplified observed (depth, density, microstructure) two-layer model with mean values distributions two multi-year tundra dataset so they could be incorporated retrieval schemes. Spatial variation depth was...
Arctic wetlands are known methane (CH
Topographical changes are of fundamental interest to a wide range Arctic science disciplines faced with the need anticipate, monitor, and respond effects climate change, including geohazard management, glaciology, hydrology, permafrost, ecology. This study demonstrates several geomorphological, cryospheric, biophysical applications ArcticDEM – large collection publicly available, time-dependent digital elevation models (DEMs) Arctic. Our illustrates ArcticDEM's applicability across different...
Hillslope runoff processes were studied in the tundra region of Canadian western arctic order to provide a physically-based, conceptual framework for generation basins this environment. It was found that subsurface flow is dominant mechanism stream channel, conveyed predominantly through peat inter-hummock channels, and highly conductive upper layer soil pipes can be as rapid surface flow. Stream discharge computed from computations hillslope meltwater input snowpack channel. The similarity...
The Mackenzie River is the largest North American source of freshwater for Arctic Ocean. This basin subjected to wide fluctuations in its climate and it currently experiencing a pronounced warming trend. As major Canadian contribution Global Energy Water Cycle Experiment (GEWEX), GEWEX Study (MAGS) focusing on understanding modeling fluxes reservoirs governing flow water energy into through system Basin. MAGS necessarily involves research many atmospheric, land surface, hydrological issues...