Early recognition by Ball and Hooker in 1878 of plant back-colonization (boomerang) events from Macaronesia to Africa

Recent work in island biogeography has shown that back-colonization (‘boomerang’ events) from islands to continents have occurred more frequently than previously understoodWe report possibly the earliest inference of this pattern, by John Ball and Joseph Dalton Hooker in a book published in 1878

The Effects of Prehydration on Cement Performance

This study investigated the effects of cement prehydration on cement’s engineering properties. Anhydrous cement was exposed over a saturated KCl solution to maintain 85% RH, for 7 and 28 days. Mortar and cement pastes were tested for strength, workability and setting time, with sample analysis by XRD and DTA. Results showed a decreased reactivity of the prehydrated cements resulting in reduced strength and increased setting times. We propose that this may be due to an upset of the sulphate balance in the cement upon prehydration

Rigid motions: action-angles, relative cohomology and polynomials with roots on the unit circle

Revisiting canonical integration of the classical solid near a uniform rotation, canonical action angle coordinates, hyperbolic and elliptic, are constructed in terms of various power series with coefficients which are polynomials in a variable $r^2$ depending on the inertia moments. Normal forms are derived via the analysis of a relative cohomology problem and shown to be obtainable without the use of ellitptic integrals (unlike the derivation of the action-angles). Results and conjectures also emerge about the properties of the above polynomials and the location of their roots. In particular a class of polynomials with all roots on the unit circle arises.Comment: 26 pages, 1 figur

Functorial properties of Putnam's homology theory for Smale spaces

We investigate functorial properties of Putnam's homology theory for Smale spaces. Our analysis shows that the addition of a conjugacy condition is necessary to ensure functoriality. Several examples are discussed that elucidate the need for our additional hypotheses. Our second main result is a natural generalization of Putnam's Pullback Lemma from shifts of finite type to non-wandering Smale spaces.Comment: Updated to agree with published versio

Improvising Linguistic Style: Social and Affective Bases for Agent Personality

This paper introduces Linguistic Style Improvisation, a theory and set of algorithms for improvisation of spoken utterances by artificial agents, with applications to interactive story and dialogue systems. We argue that linguistic style is a key aspect of character, and show how speech act representations common in AI can provide abstract representations from which computer characters can improvise. We show that the mechanisms proposed introduce the possibility of socially oriented agents, meet the requirements that lifelike characters be believable, and satisfy particular criteria for improvisation proposed by Hayes-Roth.Comment: 10 pages, uses aaai.sty, lingmacros.sty, psfig.st

The Determinants of Regional Migration in Great Britain: A Duration Approach

Using data from the first fourteen waves of the British Household Panel Survey, we estimate a discrete duration model of interregional migration in Great Britain. By exploiting retrospective information on residency we control for late entry as well as unobserved heterogeneity. We find considerable duration dependence in region of residence in the raw data, most but not all of which disappears when controlling for observable and unobservable differences between individuals. Older workers are less likely to switch region while the better educated are more mobile. There are also some differences between males and females in their likelihood to migrate.regional labour markets, panel data, hazard, duration, migration

A direct proof of Kim's identities

As a by-product of a finite-size Bethe Ansatz calculation in statistical mechanics, Doochul Kim has established, by an indirect route, three mathematical identities rather similar to the conjugate modulus relations satisfied by the elliptic theta constants. However, they contain factors like $1 - q^{\sqrt{n}}$ and $1 - q^{n^2}$, instead of $1 - q^n$. We show here that there is a fourth relation that naturally completes the set, in much the same way that there are four relations for the four elliptic theta functions. We derive all of them directly by proving and using a specialization of Weierstrass' factorization theorem in complex variable theory.Comment: Latex, 6 pages, accepted by J. Physics

Community bushfire safety: A review of post-black Saturday research

Following the 'Black Saturday' bushfires of 7 February 2009, a number of research reports on community bushfire safety were presented to the Victorian Bushfires Royal Commission. These include reports from the CFA, OESC, Bushfire CRC and Department of Justice. These reports have different research aims and employ a range of methods and samples. Some reports investigate community safety issues during the Black Saturday bushfires, while others examine preparedness and intentions for future fires. This paper reviews these reports to identify common findings, inconsistencies and gaps relating to community safety during bushfires, and discusses the implications of methodological differences for research findings

Predicting the effect of wetland restoration on phosphorus retention, Northwest Minnesota

Water quality in the Red River Valley and downstream in Lake Winnipeg has been diminishing due to excess nutrients from agriculture. One method to reduce nutrient loading to surface water is to create or restore wetlands in agricultural areas that drain cropped fields. It is commonly believed that wetlands improve water quality, but research has shown that restoring wetlands can actually release phosphorus (P) into solution. Reducing conditions caused by soil flooding can release Fe-bound P, since ferrous Fe is more soluble than ferric Fe. Little is known concerning how the soils in the Red River Valley will be affected by wetland restoration. This research at the Judicial Ditch 66 watershed in northwestern Minnesota measured soil properties to predict the effect wetland restoration will have on P retention. Surface water and groundwater samples were collected to determine P mobility and indicated very little soluble P is transported either within or out of the watershed. Soil analyses indicated that the site contains mineral soils that are Ca-rich. A phosphorus sorption index (PSI) was used to determine the degree of P soil saturation. The mean PSI was 24.7, indicating that the soils at the site have a moderately high degree of P saturation. Spearman Rank correlation coefficients show soil organic matter and exchangeable calcium correlate highest with PSI. A three-part sequential extraction was performed to determine the dominant form of soil P. Organic P comprised nearly 80% of soil P with the remaining being nearly all Ca-bound P. Throughout the study area P is associated with compounds that are not redox sensitive; therefore, it is predicted that wetland restoration will not release significant P into solution. In addition, wetlands store P by organic matter accumulation and the settling of particulate P. Wetland restoration at this site and at similar sites can be a long-term solution to improving water quality throughout the Red River Valley and in Lake Winnipeg