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Fourhorn sculpin (Myoxocephalus quadricornis) is ubiquitous in Canadian Arctic waters with a more common marine and brackish form and a rarer freshwater form. There is a paucity of information available for the freshwater form from Canadian waters. In the summer of 2003, we serendipitously collected 28 of the freshwater form of fourhorn sculpin from Lake Tuborg, Ellesmere Island, Nunavut. The fish ranged in size from 62 mm to 171 mm total length and age from 1 to 12 years with females growing faster and to a larger theoretical maximum total length than males. The sculpin preyed mainly upon the crustacean, Mysis segerstralei, but were also opportunistic feeders (e.g., Arctic charr (Salvelinus alpinus) eggs) and cannibalistic. Although our sample of fourhorn sculpin is small, the data from these fish represent the only information from a fully freshwater form population of the species from Canadian waters. We also present an updated list of the known Canadian lacustrine and riverine populations of fourhorn sculpin.

In the deepest portions of many lakes, zones of high-conductivity bottom water (HCBW) depleted in dissolved oxygen (DO) are present. HCBW and DO are important for determining benthic diversity and abundance, nutrients, and contaminant cycling and understanding the long-term evolution of lakes. We investigate the persistence and removal of HCBW and DO replenishment in a High Arctic lake using physical properties and flow velocity data along with hydrometric and suspended sediment inflow data over a 4 year monitoring period (2007–2010). HCBW was removed in 2007 and 2008 but largely remained in 2009 and 2010. Catchment disturbances in 2007 increased suspended sediment concentrations (SSC) in the inflowing river in 2007 and 2008. In the later two years of monitoring (2009 and 2010), fluvial sediment availability relaxed to pre-disturbance levels. High SSC in 2007 and 2008 caused by landscape disturbances formed sustained river-generated hyperpycnal flows during the snowmelt period that are linked to HCBW removal. In 2009 and 2010, inflowing river water was periodically denser than lake water; however, HCBW was not removed in these years. Hyperpycnal flows were likely either of insufficient strength or duration, deposited on the delta front, or followed paths that led away from the deepest portion of the lake. Results suggest that hyperpycnal flow frequency will increase and HCBW persistence will decrease with projected climate change due to an increase in fluvial SSC inflow. Water density changes resulting from increased electrical conductivity and water temperature are not likely to have a similarly large effect on hyperpycnal flow frequency and HCBW.

Wildfires can have severe and lasting impacts on the water quality of aquatic ecosystems. However, our understanding of these impacts is founded primarily from studies of small watersheds with well-connected runoff regimes. Despite the predominance of large, low-relief rivers across the fire-prone Boreal forest, it is unclear to what extent and duration wildfire-related material (e.g., ash) can be observed within these systems that typically buffer upstream disturbance signals. Following the devastating 2016 Fort McMurray wildfire in western Canada, we initiated a multi-faceted water quality monitoring program that suggested brief (hours to days) wildfire signatures could be detected in several large river systems, particularly following rainfall events greater than 10 mm. Continuous monitoring of flow and water quality showed distinct, precipitation-associated signatures of ash transport in rivers draining expansive (800–100,000 km2) and partially-burned (

The physical and chemical characteristics of two High Arctic lakes were investigated at the Cape Bounty Arctic Watershed Observatory on Melville Island, in response to large active-layer detachments generated by extreme summer temperatures in 2007. In the two years following the permafrost disturbances, there was an elevated loading of total dissolved solids into both lakes, but no concomitant increase in suspended sediment levels. The physical dynamics of one lake were significantly altered by an internal sediment input, which was not directly related to watershed processes. The results indicate that localised permafrost disturbance in the watersheds resulted in changes to chemical conditions in these relatively deep, large lakes, while increased sediment transport from disturbances did not have a sustained impact. Copyright © 2012 John Wiley & Sons, Ltd.

High Arctic river responses to changing hydroclimatic and landscape processes are poorly understood. In non-glacierized basins, snowmelt and rainfall generate river discharge, which provides first order control over fluxes. Further factors include the seasonality of precipitation, seasonal active layer development, and permafrost disturbance. These controls were evaluated in terms of sedimentary and biogeochemical fluxes from paired catchments at Cape Bounty, Melville Island, Nunavut during 2006–2009. Results indicate that the source of runoff can be more important than the amount of runoff for sediment, solutes, and organic yields. Although the snowmelt period is typically the most important time for these yields, heavy late summer precipitation events can create disproportionately large yields. Rainfall increases yields because it hydrologically connects areas otherwise isolated. Inorganic solute yields from late summer rainfall are higher because the thick active layer maximizes hydrologic interactions with mineral soils and generates high solute concentrations. Results also indicate that while the catchments are broadly similar, subtle topographic differences result in important inter-catchment differences in runoff and suspended and dissolved loads. The East watershed, which had less extensive permafrost disturbance, consistently had higher concentrations of dissolved solids. These higher dissolved fluxes cannot therefore be explained by thermokarst features, but rather by deeper active layer development, due to a greater proportion of south-facing slopes. Although warm temperatures in 2007 led to extensive active layer disturbance in the West watershed, because the disturbances were largely hydrologically disconnected, the total disturbed area was small, and inter-annual variability in discharge was high, there was no detectable response in dissolved loads to disturbances. Sediment availability increased after 2007, but yields have largely returned to pre-disturbance levels. Results indicate that seasonality and frequency-magnitude characteristics of projected increases in precipitation must be considered along with active layer changes to predict the fluvial sedimentary and biogeochemical response to regional climate change. Copyright © 2011 John Wiley & Sons, Ltd.

A macro has been developed that allows for automated statistical analyses of particles. It can be used with binary images from any source, and is developed for use with lacustrine, marine, Aeolian, and marine sediments. The macro code is freely available, and runs on open-source software. It has been specially designed to accommodate very small regions of interest relative to particle size, and to produce continuous downcore stratigraphies. The macro runs quickly, requires no user-interaction, is easily modifiable, saves 'raw data' for algorithm checking and further analyses, and can run in a mode that quantifies cracks and other disturbances on images. The macro allows for rapid analyses of relatively long sedimentary sequences, and provides relevant sedimentary interpretations of transport and depositional processes. Examples of output from two lacustrine sediment records and one marine record are shown.

Discharge and suspended sediment flux are predicted for the 21st century for the 8 km 2 West River, Cape Bounty, Melville Island in the Canadian High Arctic. Discharge predictions are made using a distributed hydrologic model, and sediment yields are predicted using a rating curve based on monitored relationships between discharge and suspended sediment concentration. Models were forced using statistically downscaled air temperature and precipitation from the A1b and A2 scenarios from the global climate model CGCM3. Under the A2 scenario, total seasonal runoff is expected to double by 2100, daily maximum discharge rates will double, and the melt season will increase in length by 30 days, mostly in autumn. Sediment yield increases will be much more extreme, and are expected to increase by 100 to 600%, but these are almost certainly minimum estimates. Variability between and within global climate models is assessed for the grid cell closest to Cape Bounty, and variability within CGCM3 is assessed by examining data from five of its runs. Intra-model variability is relatively small, but inter-model variability is large. The impact of this variability is minimized, and the applicability of results is broadened by assessing relationships between weather variables, hydrologic variables, and sediment yield for multiple model runs.

The varved sediment record from glacially-fed Lake Tuborg, Ellesmere Island, Nunavut, shows that only three large jokulhlaups have occurred there in the last millennium: 2003, 1993, and 1960. Detailed analyses of sediment microstructure and particle size, combined with in-situ hydrometeorological and limnological process studies, allowed jokulhlaup facies identification and discrimination from deposits from other processes. Deposits from large jokulhlaups are anomalously thick, typically lack internal structure, have sharp bases, and fine upwards. The ice-dammed lake above Lake Tuborg (the source of the jokulhlaups) likely changed its drainage style in 1960, from ice-dam overtopping to ice-dam flotation and glacial tunnel enlargement by melt widening, which allowed the lake to drain completely and catastrophically. Complete drainage of ice-dammed lakes by ice-dam flotation is rare in the region is due to the pervasiveness of cold-based ice. Twentieth century warming is likely responsible for some combination of dam thinning, lake expansion and deepening, and changing the thermal regime at the base of the dam. Anomalously thick individual varves were periodically deposited beginning in the nineteenth century, and their thickness increased with time. This likely reflects a combination of increased ice dam overtopping, subaqueous slope failures, sediment availability and rising air temperature. The varve record presented here significantly correlates with a previous, shorter record from Lake Tuborg. However, generally weak correlations are found between the new varve time series, regional records of air temperature, and glacial melt from ice cores on the Agassiz Ice Cap. It is hypothesized that on short timescales, sedimentation at the coring location reflects a complex and varying integration of multiple hydroclimatic, geomorphic and limnologic influences.

This paper synthesizes data collected to document the modern limnological and sedimentary processes in South Sawtooth Lake located on northern Ellesmere Island, Nunavut, Canada. Field observations show that the finely laminated sediments deposited in the distal basin are formed by the settling of overflows and interflows, and in rare occasions, by non-erosive hyperconcentrated density flows. Thin-sections of these sediments allowed for the classification of the sedimentary fabrics into six facies, each representing different limnological processes. The sediments in this distal basin are considered to be continuous and annually laminated (varved) based on radioisotope analyses, and both limnological and sedimentological evidence.

A large ice-dammed lake drained catastrophically into Lake Tuborg, Ellesmere Island, beginning on 25 July 2003. Limnological, sedimentological, and hydrological parameters were recorded before, during, and after this event. For several weeks prior to the jokulhlaup, water overtopped the ice-dammed lake and flowed into Lake Tuborg's fresh- water basin. A shallow sill separates the freshwater basin from a larger, deeper basin containing 25 PSU (practical salinity units) salt water. The sill blocked underflows from entering the saltwater basin before the jokulhlaup. The ice- dammed lake drained completely and catastrophically when englacial or subglacial conduits developed, and a glacier portal formed 980 m from the Lake Tuborg shore, marking the beginning of the jokulhlaup. The level of Lake Tuborg increased by 7.6 m in 84 h. This jokulhlaup is the largest known to have occurred in the High Arctic, and the largest witnessed in Canada since 1947. Strata of very cold water flowed above the chemocline for about 14 km, from the sill to the southwest end of the lake. The cold strata turbulently mixed with underlying salt water, allowing for saltwater flocculation of suspended sediment, causing rapid settling. The saltwater layer very slightly freshened and cooled. Close to the sill, near-surface sediments derived from the jokulhlaup are coarse and laminated; however, no erosion occurred toward the distal end of the lake, where a fining upward unit with a coarse base was deposited. Resume : Un grand lac retenu par des glaces s'est draine de maniere catastrophique dans le lac Tuborg, de l'ile Ellesmere, le 25 juillet 2003. Les parametres limnologiques, sedimentologiques et hydrologiques ont ete mesures avant, durant et apres cet evenement. Durant plusieurs semaines avant le jokulhlaup, de l'eau se deversait par-dessus le barrage de glace du lac et s'ecoulait dans le bassin d'eau douce du lac Tuborg. Un seuil peu profond separe le bassin d'eau douce d'un bassin plus grand et plus profond contenant de l'eau a une salinite d'environ 25 USP (unites de salinite pratique). Avant le jokulhlaup, le seuil empechait des courants de fond d'entrer dans le bassin d'eau salee. Le lac retenu par les glaces s'est draine completement et de maniere catastrophique lorsque des canalisations dans ou sous la glace se sont de- veloppees et qu'un portail glaciaire s'est forme a 980 m des berges du lac Tuborg, marquant ainsi le debut du jokulhlaup. Le niveau du lac Tuborg s'est eleve de 7,6 m en 84 heures. Ce jokulhlaup est le plus grand connu qui se soit produit dans le Grand Nord et le plus gros a etre vu au Canada depuis 1947. Une couche d'eau tres froide coulait par-dessus le chemocline sur une distance d'environ 14 km, depuis le seuil jusqu'a l'extremite sud-ouest du lac. La couche froide s'est melee de maniere turbulente avec l'eau salee sous-jacente engendrant une floculation des sediments en suspension dans l'eau salee et une sedimentation rapide. La couche d'eau salee est devenue legerement plus douce et plus froide. Les sediments de surface provenant du jokulhlaup, sont grossiers et lamines a proximite du seuil; toutefois, il ne s'est pas produit d'erosion a l'extremite distale du lac, ou s'est deposee une unite a base grossiere et a granodecroissance vers le haut.

Two large suspended sediment concentration (SSC) pulses were recorded in 1998 in a small snowmelt-fed stream on Ellesmere Island in the Canadian High Arctic. The largest pulse occurred from 7 to 8 July, when 32% of the monitored seasonal sediment transport occurred in only four hours. SSC reached 83,760 mg L−1, exceeding all previously recorded values from high arctic glacially-fed and snowmelt-fed rivers by more than one order of magnitude. The event occurred after the majority of snow in the watershed had melted, and was preceded by a long period of relatively high air temperature, and a small rainfall event on 7 July. We consider the most likely cause of the event to be a rapid mass movement.

Lacustrine sedimentary processes are identified on an intra-annual scale at proglacial Bear Lake, Devon Island. Stage recorders, recording thermistors, sediment traps, and underflow monitoring equi...

Combined catchment, subbottom acoustic, and sedimentary studies of high arctic, proglacial Bear Lake, Devon Island, were carried out to evaluate the role lacustrine processes and Holocene catchment evolution have had on the sedimentary record. In the proximal basin, bottom deposits up to 60 m thick are generated in part by turbid underflows associated with peak meltwater flow from the Devon Island Ice Cap. These underflows produce rhythmically laminated structures that are likely varves. In shallower locations, accumulation is slower and results from homopycnal distribution of fine suspended sediment throughout the proximal basin, resulting in a simple varve couplet. The distal basin is isolated from glacial meltwater by a shallow sill, although some fine-grained detrital carbonate transported by the glacial meltwater is deposited in both basins. In most locations in the distal basin Holocene sediments are less than 10 m thick. They are composed primarily of massive clay and some carbonate interrupted by irregular graded carbonate units produced by sporadic heavy summer rainfall and sediment transport from small plateau tributaries. Eolian sedimentation is also important throughout the lake, especially when high accumulations melt through the ice in the proximal basin, producing isolated grains and layers of coarse sand in the sedimentary record. Holocene ice margin changes have influenced the sedimentary record substantially, particularly during the mid-Holocene when the ice cap is inferred to have retreated from the catchment.

American democracy depends on civic involvement. However, many Americans are increasingly withdrawing from civic responsibility and community involvement. In his best-selling book Bowling Alone , Harvard sociologist Robert D. Putnam presents data showing that Americans have become increasingly unwilling to engage in ways that make American democracy successful. Collin County Community College (CCCC) is addressing civic disengagement through engaged scholarship collaboration between service learning and learning communities programs. Although college students are politically disengaged, most report being or having been involved in some form of community service in the previous year and say they are motivated by giving back to the community and making a difference. Engaged scholarship at CCCC draws on this interest in community service to enhance learning communities, create deeper learning for students, and instill values of citizenship and civic engagement. Learning communities classes blend courses from ...

By fusing entrepreneurs, technology and money, DaimlerChrysler attempts to duplicate a microcosm of Silicon Valley within its Palo Alto laboratory. OVERVIEW: Corporate RD the research triangle process attempts to speed up the transfer of technology via a third-party company, which is often more able to "productize" the results to corporate RD finally, we adopt a technology portfolio model that attempts to create future capabilities for the parent company by investing in technology companies that are ahead of their time. The technology portfolio creates a collection of companies that continue to develop new technologies even after the corporate R&D projects have been postponed or canceled. It is too early to determine if these techniques work. Rather, we are only at the formative stage of development of these ideas. One of the more controversial concepts is that of the equity pool for corporate R&D employees. This pool is created by taking a small equity position in the many companies we invest in, and sharing this equity with employees of the corporate R&D lab. This will undoubtedly change the culture of the lab and hopefully create a sense of urgency similar to that of a Silicon Valley startup. The Current Environment Corporate R&D organizations find themselves in an unusual environment because of the rapid rise of telecommunications and the exponential growth in the use of information technology to accelerate most business processes. This environment is characterized by: 1. Speed.-Technology adoption rates are an order of magnitude faster than several decades ago, which means that technologies and products are penetrating global markets faster and faster. For example, the common household telephone took over 60 years to achieve 50-percent penetration in U.S. homes. Today, the World Wide Web achieved 50-percent penetration of U.S. homes in a mere five years, and it is expected to reach similar levels in modern industrialized nations across the globe in roughly 10 years. Technology diffusion is occurring approximately 10 times faster today than 50-100 years ago. 2. Increasing Returns.-The current environment is driven by the law of increasing returns, which states that the more of something there is in the world, the more valuable that something becomes. Increasing returns theory is counter to the notion of diminishing returns-the predominant theory that has dominated the "old economy. …

When C is a ball in ${\Bbb R}^d$ and S is the sphere $\partial C$ , we say that S supports a convex body B if S intersects B and either $B\subseteq C$ (then S is a far support) or the interior of C is disjoint from B (then S is a near support). The focus here is on common supports for a system $\cal B$ of d+1 bodies in ${\Bbb R}^d$ such that for each way of selecting a point from each member of ${\cal B}$ , the selected points are affinely independent and hence form the vertex-set of a d-simplex. The main result asserts that if $({\cal B}',{\cal B}'')$ is an arbitrary partition of ${\cal B}$ , then there exists a unique Euclidean sphere that is simultaneously a near support for each member of ${\cal B}'$ and a far support for each member of ${\cal B}''$ .

A family S of sets in R d is sundered if for each way of choosing a point from r≤d+1 members of S, the chosen points form the vertex-set of an (r−1)-simplex. Bisztriczky proved that for each sundered family S of d convex bodies in R d , and for each partition (S ′, S ″), of S, there are exactly two hyperplanes each of which supports all the members of S and separates the members of S ′ from the members of S ″. This note provides an alternate proof by obtaining each of the desired supports as (in effect) a fixed point of a continuous self-mapping of the cartesian product of the bodies.

(1995). The Kissing Number of the Square. Mathematics Magazine: Vol. 68, No. 2, pp. 128-133.

A sequence (A1,…,An) of nonempty subsets of R m is an S-system if for each choice of a1∈A1,…,an∈An, the nullspace of the matrix [a1,…,an] is a line that penetrates the strictly positive orthant of R n. For the case in which each Aj is a sign cone, S-systems are basic to the study of the sign-solvability of systems of linear equations; in that case, they can be recognized in time O(m2). The present paper provides several characterizations of general S-systems and describes a polynomial-time algorithm (based on linear programming) for the recognition of such systems when the Aj are arbitrary finitely presented convex cones.

We construct a family ofn disjoint convex set in ?d having (n/(d?1))d?1 geometric permutations. As well, we complete the enumeration problem for geometric permutations of families of disjoint translates of a convex set in the plane, settle the case for cubes in ?d, and construct a family ofd+1 translates in ?d admitting (d+1)!/2 geometric permutations.