Routes and Roots

Publisher PD

Colouring Lines in Projective Space

Let $V$ be a vector space of dimension $v$ over a field of order $q$. The $q$-Kneser graph has the $k$-dimensional subspaces of $V$ as its vertices, where two subspaces $\alpha$ and $\beta$ are adjacent if and only if $\alpha\cap\beta$ is the zero subspace. This paper is motivated by the problem of determining the chromatic numbers of these graphs. This problem is trivial when $k=1$ (and the graphs are complete) or when $v<2k$ (and the graphs are empty). We establish some basic theory in the general case. Then specializing to the case $k=2$, we show that the chromatic number is $q^2+q$ when $v=4$ and $(q^{v-1}-1)/(q-1)$ when $v > 4$. In both cases we characterise the minimal colourings.Comment: 19 pages; to appear in J. Combinatorial Theory, Series

J/ψ\psi Production in p+p and d+Au Collisions at SNN\sqrt{S_{NN}} = 200 GeV at STAR

We present analysis of J/$\psi$ production over the range $-1.0 < \eta < 4.2$ in p+p and d+Au collisions using di-electron data taken during the 2008 run with the STAR experiment at Brookhaven National Laboratory. STAR's unique forward capabilities, especially the Forward Meson Spectrometer electromagnetic calorimeter, allow us the possibility of investigating the intrinsic charm components of the proton wave function using high-$x_F$ forward particles produced in asymmetric partonic collisions. Mid-rapidity measurements in d+Au collisions extend our understanding of the mechanisms underlying heavy quarkonium production and its transport through cold nuclear matter.Comment: 4 pages, 3 figures, - to appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

Identifying High Potential Police Officers and Role Characteristics.

Project commissioned in 2000 by the Metropolitan Police Service to carry out a psychometric assessment validation study as part of a career Pathways Project

Incorporating spatial variation in housing attribute prices: A comparison of geographically weighted regression and the spatial expansion method

Hedonic house price models typically impose a constant price structure on housing characteristics throughout an entire market area. However, there is increasing evidence that the marginal prices of many important attributes vary over space, especially within large markets. In this paper, we compare two approaches to examine spatial heterogeneity in housing attribute prices within the Tucson, Arizona housing market: the spatial expansion method and geographically weighted regression (GWR). Our results provide strong evidence that the marginal price of key housing characteristics varies over space. GWR outperforms the spatial expansion method in terms of explanatory power and predictive accuracy.