309 research outputs found
Rough linear transport equation with an irregular drift
We study the linear transport equation
where is a vectorfield of limited regularity and a vector-valued
H\"older continuous driving term. Using the theory of controlled rough paths we
give a meaning to the weak formulation of the PDE and solve that equation for
smooth vectorfields . In the case of the fractional Brownian motion a
phenomenon of regularization by noise is displayed
The emergence of French statistics. How mathematics entered the world of statistics in France during the 1920s
This paper concerns the emergence of modern mathematical statistics in France
after the First World War. Emile Borel's achievements are presented, and
especially his creation of two institutions where mathematical statistics was
developed: the {\it Statistical Institute of Paris University}, (ISUP) in 1922
and above all the {\it Henri Poincar\'e Institute} (IHP) in 1928. At the IHP, a
new journal {\it Annales de l'Institut Henri Poincar\'e} was created in 1931.
We discuss the first papers in that journal dealing with mathematical
statistics
Rough flows and homogenization in stochastic turbulence
We provide in this work a tool-kit for the study of homogenisation of random
ordinary differential equations, under the form of a friendly-user black box
based on the tehcnology of rough flows. We illustrate the use of this setting
on the example of stochastic turbulence.Comment: v2, 27 pages; presentation fairly improved; extended scope for the
materia
Pensacola\u27s Cast Iron Architecture
Late at night on July 5, 1880, while most of Pensacola\u27s citizens were sleeping, flames erupted from Cheap John\u27s Clothing Store. The flames became a blaze that eventually destroyed most of the buildings west of the public square. Five months later, an even more devastating fire consumed Pensacola\u27s downtown business district. On December 11, over 100 buildings burned, including Pensacola\u27s two newspaper buildings, every drug store, stationery store, and even the telegraph offices. As the year 1880 ended, over ninety percent of Pensacola\u27s commercial structures had succumbed to flames, and antebellum Pensacola lay in ruins.
Evaluating threats and management practices for the conservation of hairy prairie-clover (Dalea villosa Nutt. (Spreng) var. villosa), a rare plant species in Saskatchewan
Hairy prairie-clover (Dalea villosa Nutt. (Spreng) var. villosa), a rare plant species, grows in the Canadian Prairies. Populations of Dalea in Canada are threatened by the loss of sand dune habitat because of changes in land use and altered ecological processes such as grazing and fire. Local populations of Dalea are further threatened by one or more specific threats, including herbivory from native and domestic ungulates and invasion of habitats by exotic plants. The overall objective of this thesis was to gain more knowledge about Dalea and to determine the impact of threats and management practices to the Saskatchewan populations and their habitats. Observational studies were conducted at each of two sites in Saskatchewan supporting Dalea. First, at the Dundurn Sandhills site, structural equation modeling was used to examine landscape, ecological, and management factors associated with high rates of herbivory on Dalea and with reductions in the long-term survival and productivity of Dalea. The conditions which deer (Odocoileus hemionus and Odocoileus virginianus) or cattle (Bos taurus) were responsible for the most intense rates of herbivory to Dalea plants and patches were determined. Generally, deer appeared responsible for the most herbivory, whereas cattle grazing on Dalea increased with stocking densities. At the same time, new hypotheses about ecological processes affecting Dalea productivity in the Dundurn Sandhills were explored. In particular, it appeared that deer may be responding to cattle grazing in Dalea habitat by avoiding those areas, and that mid-season germination and recruitment of many Dalea plants may occur following precipitation events. Second, at the Mortlach site, the costs and benefits of using grazing management to control leafy spurge (Euphorbia esula L. var. esula) were assessed, especially in consideration of the potential negative effects of intense herbivory on Dalea productivity. Aspects of the grazing regime including stocking density and the livestock species influenced herbivory on Dalea and its reproductive output, but there were no apparent links between the abundance of leafy spurge abundance and the reproductive output of Dalea. The findings of these two studies are relevant for the conservation and management of Dalea in Saskatchewan
Urban Containment Policies and Physical Activity A Time–Series Analysis of Metropolitan Areas, 1990–2002
Background: Urban containment policies attempt to manage the location, character, and timing of growth to support a variety of goals such as compact development, preservation of greenspace, and efficient use of infrastructure. Despite prior research evaluating the effects of urban containment policies on land use, housing, and transportation outcomes, the public health implications of these policies remain unexplored. This ecologic study examines relationships among urban containment policies, state adoption of growthmanagement legislation, and population levels of leisure and transportation-related physical activity in 63 large metropolitan statistical areas from 1990 to 2002. Methods: Multiple data sources were combined, including surveys of urban containment policies, the Behavioral Risk Factor Surveillance System, the U.S. Census of Population, the National Resources Inventory, and the Texas Transportation Institute Urban Mobility Study. Mixed models were used to examine whether urban containment policies and state adoption of growth-management legislation were associated with population levels of leisure-time physical activity (LTPA) and walking/bicycling to work over time. Results: Strong urban containment policies were associated with higher population levels of LTPA and walking/bicycling to work during the study period. Additionally, residents of states with legislation mandating urban growth boundaries reported significantly more minutes of LTPA/week compared to residents of states without such policies. Weak urban containment policies showed inconsistent relationships with physical activity. Conclusions: This study provides preliminary evidence that strong urban containment policies are associated with higher population levels of LTPA and active commuting. Future research should examine potential synergies among state, metropolitan, and local policy processes that may strengthen these relationship
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