Faà di Bruno’s formula and spatial cluster modelling

AbstractThe probability generating functional (p.g.fl.) provides a useful means of compactly representing point process models. Cluster processes can be described through the composition of p.g.fl.s, and factorial moment measures and Janossy measures can be recovered from the p.g.fl. using variational derivatives. This article describes the application of a recent result in variational calculus, a generalisation of Faà di Bruno’s formula, to determine such results for cluster processes

Roosting, Site Fidelity, and Food Sources of Urban Gulls In Massachusetts: Implications For Protecting Public Water Supplies

Anyone who has spent time in coastal New England has seen gulls flying overhead and heard their familiar sound; gulls may be one of the most recognizable birds in the world. There are over 50 species of gulls worldwide, and many of them are closely associated with human development or activities. In Massachusetts, there are several common gull species including herring (Larus argentatus), great black-back (Larus marinus), laughing (Leucophaeus atricilla), and ring-billed (Larus delawarensis). While coastal encounters with gulls are ubiquitous, gulls can also be found inland, and ring-billed and herring gulls are now a common sight at lakes, parks, and commercial parking lots dozens or hundreds of kilometers from the ocean. This inland population of gulls presents unique challenges and exciting research opportunities. Because they are often closely associated with human activity, concentrations of inland gulls can lead to potential water quality concerns (when large roosts form on public water supply reservoirs), airplane hazards (when groups of gulls concentrate near airports or flight paths), or disease transmission (when gulls forage at landfills or waste water treatment plants then visit areas with people). In the following chapters I explore various aspects of inland gull ecology during the non-breeding season. In chapter 1, I review the concept of philopatry in birds and discuss ways to assess site faithful behavior. In Chapters 2 and 3, I explore some of the ecological aspects of inland gulls. Chapter 2 examines the site fidelity of gulls to their wintering areas and my results suggest that gulls exhibit high winter-site fidelity but variable site persistence during the winter season. Chapter 3 explores roost site selection throughout the year and models roost selection in Massachusetts. My results indicate that ring-billed gulls prefer freshwater roosts, while herring gulls use saltwater roosts more often. In Massachusetts, both herring and ring-billed gulls select inland freshwater roosts based on the size of the water body and proximity to their last daytime location. In Chapter 4, I detail the results of an experimental study trying to reduce the amount of anthropogenic food available to gulls at inland parking lots. Ring-billed gulls were the most common gull found in parking lots, and my educational approach to reduce feedings had mixed results; education seemed to reduce the number of feedings in some cases, but the number of gulls in each parking lot was not affected. In Chapters 5 and 6, I detail some applied management techniques. Chapter 5 discusses efforts to exclude gulls from a waste water treatment plant in central Massachusetts. Overhead stainless-steel wires were completely effective at preventing gulls from using structures at the treatment plant. Chapter 6 describes an innovative technique that was used to efficiently and effectively catch gulls during winter in highly urbanized environments. I captured over 1000 gulls using a net launcher in various parking lots and other urban areas

Finite-temperature effects in helical quantum turbulence

We perform a study of the evolution of helical quantum turbulence at different temperatures by solving numerically the Gross-Pitaevskii and the stochastic Ginzburg-Landau equations, using up to 40963 grid points with a pseudospectral method. We show that for temperatures close to the critical one, the fluid described by these equations can act as a classical viscous flow, with the decay of the incompressible kinetic energy and the helicity becoming exponential. The transition from this behavior to the one observed at zero temperature is smooth as a function of temperature. Moreover, the presence of strong thermal effects can inhibit the development of a proper turbulent cascade. We provide Ansätze for the effective viscosity and friction as a function of the temperature.Fil: Clark Di Leoni, Patricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. University of Rome Tor Vergata; ItaliaFil: Mininni, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Brachet, Marc E.. Universite Pierre et Marie Curie; Franci

Dynamics of partially thermalized solutions of the Burgers equation

The spectrally truncated, or finite dimensional, versions of several equations of inviscid flows display transient solutions which match their viscous counterparts, but which eventually lead to thermalized states in which energy is in equipartition between all modes. Recent advances in the study of the Burgers equation show that the thermalization process is triggered after the formation of sharp localized structures within the flow called "tygers." We show that the process of thermalization first takes place in well defined subdomains, before engulfing the whole space. Using spatio-temporal analysis on data from numerical simulations, we study propagation of tygers and find that they move at a well defined mean speed that can be obtained from energy conservation arguments.Fil: Clark Di Leoni, Patricio. University of Rome “Tor Vergata”; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Mininni, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Brachet, Marc E.. Université Paris Diderot - Paris 7; Franci

A second-order PHD filter with mean and variance in target number

The Probability Hypothesis Density (PHD) and Cardinalized PHD (CPHD) filters are popular solutions to the multi-target tracking problem due to their low complexity and ability to estimate the number and states of targets in cluttered environments. The PHD filter propagates the first-order moment (i.e. mean) of the number of targets while the CPHD propagates the cardinality distribution in the number of targets, albeit for a greater computational cost. Introducing the Panjer point process, this paper proposes a second-order PHD filter, propagating the second-order moment (i.e. variance) of the number of targets alongside its mean. The resulting algorithm is more versatile in the modelling choices than the PHD filter, and its computational cost is significantly lower compared to the CPHD filter. The paper compares the three filters in statistical simulations which demonstrate that the proposed filter reacts more quickly to changes in the number of targets, i.e., target births and target deaths, than the CPHD filter. In addition, a new statistic for multi-object filters is introduced in order to study the correlation between the estimated number of targets in different regions of the state space, and propose a quantitative analysis of the spooky effect for the three filters