University of Victoria

About: University of Victoria is a education organization based out in Victoria, British Columbia, Canada. It is known for research contribution in the topics: Population & Galaxy. The organization has 14994 authors who have published 41051 publications receiving 1447972 citations. The organization is also known as: Victoria College.

Absence of deep-water formation in the Labrador Sea during the last interglacial period

Abstract: The two main constituent water masses of the deep North Atlantic Ocean—North Atlantic Deep Water at the bottom and Labrador Sea Water at an intermediate level—are currently formed in the Nordic seas and the Labrador Sea, respectively1. The rate of formation of these two water masses tightly governs the strength of the global ocean circulation and the associated heat transport across the North Atlantic Ocean2. Numerical simulations have suggested a possible shut-down of Labrador Sea Water formation as a consequence of global warming3. Here we use micropalaeontological data and stable isotope measurements in both planktonic and benthic foraminifera from deep Labrador Sea cores to investigate the density structure of the water column during the last interglacial period, which was thought to be about 2 °C warmer than present4. Our results indicate that today's stratification between Labrador Sea Water and North Atlantic Deep Water never developed during the last interglacial period. Instead, a buoyant surface layer was present above a single water mass originating from the Nordic seas. Thus the present situation, with an active site of intermediate-water formation in the Labrador Sea, which settled some 7,000 years ago, has no analogue throughout the last climate cycle.

Interaction of maturation delay and nonlinear birth in population and epidemic models.

Abstract: A population with birth rate function B(N) N and linear death rate for the adult stage is assumed to have a maturation delay T>0. Thus the growth equation N′(t)=B(N(t−T)) N(t−T) e− d 1 T−dN(t) governs the adult population, with the death rate in previous life stages d 1≧0. Standard assumptions are made on B(N) so that a unique equilibrium N e exists. When B(N) N is not monotone, the delay T can qualitatively change the dynamics. For some fixed values of the parameters with d 1>0, as T increases the equilibrium N e can switch from being stable to unstable (with numerically observed periodic solutions) and then back to stable. When disease that does not cause death is introduced into the population, a threshold parameter R 0 is identified. When R 0<1, the disease dies out; when R 0>1, the disease remains endemic, either tending to an equilibrium value or oscillating about this value. Numerical simulations indicate that oscillations can also be induced by disease related death in a model with maturation delay.

How Information Visualization Novices Construct Visualizations

Abstract: It remains challenging for information visualization novices to rapidly construct visualizations during exploratory data analysis. We conducted an exploratory laboratory study in which information visualization novices explored fictitious sales data by communicating visualization specifications to a human mediator, who rapidly constructed the visualizations using commercial visualization software. We found that three activities were central to the iterative visualization construction process: data attribute selection, visual template selection, and visual mapping specification. The major barriers faced by the participants were translating questions into data attributes, designing visual mappings, and interpreting the visualizations. Partial specification was common, and the participants used simple heuristics and preferred visualizations they were already familiar with, such as bar, line and pie charts. We derived abstract models from our observations that describe barriers in the data exploration process and uncovered how information visualization novices think about visualization specifications. Our findings support the need for tools that suggest potential visualizations and support iterative refinement, that provide explanations and help with learning, and that are tightly integrated into tool support for the overall visual analytics process.

Impacts from climate change on organizations: a conceptual foundation

Abstract: Physical impacts from climate change already pose major challenges for organizations, and the trend is rising. Organization theorists, however, have barely begun to systematically consider the organizational impacts of more and increasingly intense storms, floods, droughts, fires, sea level rise or changing growing seasons as part of their domain of study. Eight organizationally relevant dimensions of climate impacts are identified: severity, temporal scale, spatial scale, predictability, mode, immediacy, state change potential and accelerating trend potential. Combined, their scale, scope and systemic uncertainty suggest future conditions of systemic hyperturbulence in organizational environments, defined here as 'massive discontinuous change' (MDC). To build a conceptual foundation for organizations to respond and adapt to MDC, the paper examines contributions from literatures on the management of sustainability, crisis, risk, resilience and adaptive organizational change. It highlights gaps for addressing both business challenges and opportunities from MDC, and suggests avenues for future research.

Anthropogenic Influence on Long Return Period Daily Temperature Extremes at Regional Scales

Abstract: Observed 1961–2000 annual extreme temperatures, namely annual maximum daily maximum (TXx) and minimum (TNx) temperatures and annual minimum daily maximum (TXn) and minimum (TNn) temperatures, are compared with those from climate simulations of multiple model ensembles with historical anthropogenic (ANT) forcing and with combined anthropogenic and natural external forcings (ALL) at both global and regional scales using a technique that allows changes in long return period extreme temperatures to be inferred. Generalized extreme value (GEV) distributions are fitted to the observed extreme temperatures using a time-evolving pattern of location parameters obtained from model-simulated extreme temperatures under ANT or ALL forcing. Evaluation of the parameters of the fitted GEV distributions shows that both ANT and ALL influence can be detected in TNx, TNn, TXn, and TXx at the global scale over the land areas for which there are observations, and also regionally over many large land areas, with detect...