Ice Bear: The Cultural History of an Arctic Icon by Michael Engelhard

Review of Michael Engelhard\u27s Ice Bear: The Cultural History of an Arctic Icon

Point and Lie Bäcklund symmetries of certain partial differential equations : a thesis presented in partial fulfilment of the requirements for the degree of MA in Mathematics at Massey University

The aim of this thesis is to: (1) Explore the use of differential forms in obtaining point and contact symmetries of particular partial differential equations (PDEs) and hence their corresponding similarity solutions. [1] and [4]. (2) Explore the generalized or Lie-Bäcklund symmetries of particular PDEs with particular reference to the Korteweg-de Vries-Burgers (KdVB) equation [3]. Finding point symmetries of a PDE H = 0 with independent variables (x1,x2 ) which we take to represent space and time and dependent variable (u) means finding the transformation group that takes the variables (x1, x2, u) to the system (x´1, x´2 , u´ ) and maps solutions of H = 0 into solutions of the same equation. The form of H = 0 remains invariant. The transformation group is usually expressed in terms of its infinitesimal generator (X) where using the tensor summation convention. X can be considered as a differential vector operator with components (ξ1 , ξ2 , η) operating in a three dimensional manifold (space) with coordinates (x1 , x2 , u). The invariance of H = 0 under the transformation group is expressed in terms of a suitable prolongation or extension of X (denoted by X(pr) ) to cover the effect of the transformations on the derivatives of u in H = 0. The invariance condition for H = 0 under the action of the transformation group is (Pr) [H] = 0 whenever H = 0. We consider x1 , x2 , u and the derivatives of u to be independent variables. In practical terms, finding point symmetries of H = 0 means finding the components (ξ1 , ξ2 , η) of the infinitesimal generator (X). There are two general methods for finding ξ1 , ξ2 η. [From Introduction] [NB: Mathematical/chemical formulae or equations have been omitted from the abstract due to website limitations. Please read the full text PDF file for a complete abstract.

An Environmental History of Medieval Europe by Richard C. Hoffman

Review of Richard C. Hoffman\u27s An Environmental History of Medieval Europe

Macro vs. Micro Methods in Non-Life Claims Reserving (an Econometric Perspective)

Traditionally, actuaries have used run-off triangles to estimate reserve ("macro" models, on agregated data). But it is possible to model payments related to individual claims. If those models provide similar estimations, we investigate uncertainty related to reserves, with "macro" and "micro" models. We study theoretical properties of econometric models (Gaussian, Poisson and quasi-Poisson) on individual data, and clustered data. Finally, application on claims reserving are considered

Hydrodynamic nucleation of vortices and solitons in a resonantly excited polariton superfluid

We present a theoretical study of the hydrodynamic properties of a quantum gas of exciton-polaritons in a semiconductor microcavity under a resonant laser excitation. The effect of a spatially extended defect on the superfluid flow is investigated as a function of the flow speed. The processes that are responsible for the nucleation of vortices and solitons in the wake of the defect are characterized, as well as the regimes where the superfluid flow remains unperturbed. Specific features due to the non-equilibrium nature of the polariton fluid are put in evidence

"Did the Clinton Rising Tide Raise All Boats? Job Opportunity for the Less Skilled"

During the recent robust expansion only 700,000 of the almost 12 million jobs created went to the half of the population that does not have at least some college education. Even though the number of officially unemployed fell to less than 4 million in the 25 and over age group, there remain in that age group over 26 million potentially employable workers—the combined number of those who are actively seeking work (and are counted as officially unemployed) and those who are currently out of the labor force but would be willing to participate. Since expansion has not proven sufficient to remedy this intolerably high level of wasted human resources, well-targeted, active labor market policies are required. One such policy is a job opportunity program that "hires off the bottom," providing minimum-wage jobs for all those who are ready, willing, and able to work. The program would create a buffer stock of labor from which employers could hire during upturns instead of bidding up the wages of the already employed and thus would offer both full employment and price stability.

Validation of a multi-residue method to determine deltamethrin and alpha-cypermethrin in mosquito nets by gas chromatography with electron capture detection (GC-µECD)

Background: Nowadays long-lasting insecticidal mosquito nets (LNs) are frequently used around the world to protect people against malaria vectors. As they contain insecticide, laboratory control is needed to check whether the content of the active ingredient follows the conditions of the manufacturer and also if the active ingredient is still present after some time of use. For this purpose, an analytical method had to be developed. The fact that LNs include a range of polymers for the yarn and use coated or incorporated technologies for the active ingredient, it is a challenge to find only one analytical method determining the active ingredient in LNs, which takes into account both impregnation technologies. Some methods are provided by international organizations but are limited by the determination of only one pesticide per method. The aim of this study was to optimize a short time extraction method for deltamethrin and alpha-cypermethrin from coated and incorporated mosquito nets and also to detect both insecticides in one analytical run, using gas chromatography with electron capture detection (GC-mu ECD). Methods: Based on the literature, the most suitable solvent and the adequate extraction process for the insecticides used for net making were identified and adapted for the new multi-residue method. Results: The validation data of the multi-residue method to determine deltamethrin and alpha-cypermethrin in mosquito nets by GC-mu ECD are given. Depending on the concentration of the active ingredient spiked on the nets, the mean recovery for alpha-cypermethrin ranged between 86% and 107% with a relative standard deviation below 3.5%. For deltamethrin it ranged between 90% and 108% with a relative standard deviation also below 3.5%. The limit of detection is 0.009 g.a.i/kg of net (0.3 mg a.i./m(2) of net) both for alpha-cypermethrin and deltamethrin. Conclusions: Data obtained are excellent. A 30 minutes reflux extraction method with xylene was developed to determine alpha-cypermethrin and deltamethrin in long-lasting insecticidal mosquito nets (LNs) by gas chromatography with electron capture detection (GC-mu ECD). The method can be easily extended to others pyrethroid used for mosquito net treatment. This paper also presents an overview of the studies dealing with pesticide determination in mosquito nets

Catastrophes dites naturelles, risques et développement durable : Utilisations géographiques de la courbe de Farmer

L’article vise à montrer comment la courbe de Farmer permet de représenter à la fois les risques, les catastrophes dites naturelles et le développement durable. Elle peut aider à comprendre et à formaliser les relations qui peuvent exister entre ces notions, en s’appuyant sur les travaux de terrain que mènent les géographes. En effet, l’augmentation des catastrophes que présentent les bases de données comme EM-Dat n’est pas incompatible avec la notion de développement durable. Les politiques visant à augmenter la résilience des sociétés locales, et à réduire le niveau des dommages en cas de survenue d’un futur événement, apparaissent très compatibles avec les principes fondamentaux du développement durable. Ce qui n’empêche pas qu’elles produisent aussi de nombreux effets non désirés qui ne peuvent être totalement anticipés. Les géographes les identifient lors de leurs travaux de terrain. Ceci est très cohérent avec le fait que la courbe de Farmer soit considérée comme un moyen de représenter la complexité.This paper aims at justifying how the well-known Farmer’s curve may be used as a means to formalize relationships between risks, so-called natural disasters and sustainable development. It may help geographers to clarify these relationships relying on mainly post-disasters field survey experiences. We find that sustainable development cannot be challenged by the increasing disaster frequencies main databases display, such as EM-DAT. Policies wishing to strengthen local societies resilience, and aiming at reducing the intensities of damages for the next events, seem to be consistent with the fundamentals of sustainable development. At the same time, they produce unwanted and not fully predictable effects geographers find back during field surveys. This is consistent with the fact that farmer’s curve may be considered a means to identify complexity