Distance colouring without one cycle length

We consider distance colourings in graphs of maximum degree at most $d$ and how excluding one fixed cycle length $\ell$ affects the number of colours required as $d\to\infty$. For vertex-colouring and $t\ge 1$, if any two distinct vertices connected by a path of at most $t$ edges are required to be coloured differently, then a reduction by a logarithmic (in $d$) factor against the trivial bound $O(d^t)$ can be obtained by excluding an odd cycle length $\ell \ge 3t$ if $t$ is odd or by excluding an even cycle length $\ell \ge 2t+2$. For edge-colouring and $t\ge 2$, if any two distinct edges connected by a path of fewer than $t$ edges are required to be coloured differently, then excluding an even cycle length $\ell \ge 2t$ is sufficient for a logarithmic factor reduction. For $t\ge 2$, neither of the above statements are possible for other parity combinations of $\ell$ and $t$. These results can be considered extensions of results due to Johansson (1996) and Mahdian (2000), and are related to open problems of Alon and Mohar (2002) and Kaiser and Kang (2014).Comment: 14 pages, 1 figur

The Biology of Canadian Weeds. 131. \u3cem\u3ePolygonum aviculare\u3c/em\u3e L.

A review and assessment of biological information as well as personal data are provided for Polygonum aviculare in Canada. The species has been revised taxonomically and the six subspecies that occur in Canada are presented. Three of the subspecies, P. aviculare subsp. aviculare, P. aviculare subsp. neglectum and P. aviculare subsp. depressum are weeds introduced to Canada from Europe. A fourth subspecies, P. aviculare subsp. buxiforme is apparently native to North America. The geographical distribution of the latter four subspecies is very wide. Plants exhibit a high phenotypic plasticity and genetic variability, and they easily adapt to a multitude of agrestal and ruderal habitats. The seeds have a variable dormancy and polymorphic germination as a result of heterocarpy, genetic and environmental factors. In other areas (Europe), the species has developed resistance to triazines. Plants are hosts to nematodes, viruses, and fungi that also affect cultivated plants

The Biology of Canadian Weeds. 126. \u3cem\u3eAmaranthus albus\u3c/em\u3e L., \u3cem\u3eA. blitoides\u3c/em\u3e S. Watson and \u3cem\u3eA. blitum\u3c/em\u3e L.

A review of biological information is provided for three species of the genus Amaranthus: A. albus L., A. blitoides S. Watson and A. blitum L. The last species has been revised taxonomically and a new subspecies for Canada is presented—A. blitum subsp. emarginatus (Moq. ex Uline & Bray) Carretero, Munoz Garmendia & Pedrol. Amaranthus albus and A. blitoides are native to the U.S.A. and introduced to Canada. Both species are annual ruderal and agrestal weeds. During the past 100 yr the two species have spread across most provinces of Canada, but the greatest frequency and abundance have been recorded in Saskatchewan. Originating from Europe, Asia and North Africa, A. blitum was initially considered a non-persistent species. The present study shows that A. blitum especially, subsp. emarginatus, has continued to spread in Québec. The three species are alternate hosts to many insects, nematodes, viruses, bacteria and fungi that affect cultivated plants. In other areas (U.S.A., Europe and Asia), the three species have developed multiple resistance to triazine and acetolactate-synthase-inhibiting herbicides

The relationship between insurance growth and economic development - 80 empirical papers for a review of the literature

The objective is to examine the determinants of the relationship between insurance growth and economic development. This paper contributes to this body of research by providing an extensive literature review of empirical studies that have looked at both sides of the relationship, i.e. the demand side (economic growth is an explanatory variable among other factors that affect the demand) and the development side (insurance is a determinant of growth).Insurance demand, financial development¸ economic growth.

The Biology of Canadian Weeds. 133. \u3cem\u3eCuscuta campestris\u3c/em\u3e Yuncker, \u3cem\u3eC. gronovii\u3c/em\u3e Willd. ex Schult., \u3cem\u3eC. umbrosa\u3c/em\u3e Beyr. ex Hook., \u3cem\u3eC. epithymum\u3c/em\u3e (L.) L. and \u3cem\u3eC. epilinum\u3c/em\u3e Weihe

Cuscuta spp. (dodders) are rootless, holoparasitic herbs with filiform stems attached to the host by numerous haustoria. In Canada, Cuscuta gronovii is the most common native species of the genus followed by Cuscuta campestris and C. umbrosa. Cuscuta epithymum and C. epilinum, both introduced species in Canada, occur occasionally. Infestation by Cuscuta spp. can result in serious yield losses and dodders are listed as noxious weeds in British Columbia, Ontario and Québec, and as restricted weeds in Alberta. These plants have evolved special adaptations to ensure their success: germination occurs late in the season when potential hosts are already established; seedlings selectively forage in plant communities and they may survive relatively long periods during the autotrophic stage. Invasion occurs via extremely elaborate mechanisms designed to match the biological processes of their host and bypass defense mechanisms. The principal means of dispersal of Cuscuta weeds world-wide (including Canada) has been through contaminated seeds of previously infested forage legumes. In other areas (e.g., Israel), C. campestris has developed resistance to ALS inhibitors (chlorsulfuron, and sulfometuron-methyl) and AABI herbicides. Complete descriptions and illustrations are provided for discussed species

FINANCIAL DEVELOPMENT, HUMAN CAPITAL AND POLITICAL STABILITY

In this paper we take a look at the empirical relationship between the level of financial development and socio-economic variables reflecting different levels of development in the light of the recent literature on the role of human capital in economic development. The empirical results, based on a cross-sectional analysis of 57 developing countries, indicate that human capital and socio-political stability are important factors explaining the level of financial development of these markets.

Kurtosis in Large-Scale Structure as a Constraint on Non-Gaussian Initial Conditions

We calculate the kurtosis of a large-scale density field which has undergone weakly non-linear gravitational evolution from arbitrary non-Gaussian initial conditions. It is well known that the weakly evolved {\twelveit skewness} is equal to its initial value plus the term induced by gravity, which scales with the rms density fluctuation in precisely the same way as for Gaussian initial conditions. As in the case of skewness, the evolved {\twelveit kurtosis} is equal to its initial value plus the contribution induced by gravity. The scaling of this induced contribution, however, turns out to be qualitatively different for Gaussian versus non-Gaussian initial conditions. Therefore, measurements of the kurtosis can serve as a powerful discriminating test between the hypotheses of Gaussian and non-Gaussian nature of primordial density fluctuations.Comment: uuencoded compressed tar file including postscript text (17 pages) and 2 postscript figures, submitted to MNRA

Cities versus agriculture: revisiting intersectoral water transfers, potential gains and conflicts

Water scarcity / Water demand / Water transfer / Water use / Water supply / Water allocation / Environmental effects / Water market