Bridge number and integral Dehn surgery

In a 3-manifold M, let K be a knot and R be an annulus which meets K transversely. We define the notion of the pair (R,K) being caught by a surface Q in the exterior of the link given by K and the boundary curves of R. For a caught pair (R,K), we consider the knot K^n gotten by twisting K n times along R and give a lower bound on the bridge number of K^n with respect to Heegaard splittings of M -- as a function of n, the genus of the splitting, and the catching surface Q. As a result, the bridge number of K^n tends to infinity with n. In application, we look at a family of knots K^n found by Teragaito that live in a small Seifert fiber space M and where each K^n admits a Dehn surgery giving the 3-sphere. We show that the bridge number of K^n with respect to any genus 2 Heegaard splitting of M tends to infinity with n. This contrasts with other work of the authors as well as with the conjectured picture for knots in lens spaces that admit Dehn surgeries giving the 3-sphere

Are Wild Bee Pollinator Populations Declining?

How climate change may affect insect pollinator populations in the Midwest.Environmental Change Institute UIUCAgroecology and Sustainable Agriculture Program UIUCunpublishednot peer reviewe

INTERNATIONAL EFFECTS OF CANADA'S WESTERN GRAIN STABILIZATION PROGRAM

Canada's Western Grain Stabilization program is analyzed to determine the extent to which it acts as a buffer between the Canadian grains economy and the international grains economy. A dynamic stochastic simulation model is constructed to examine how Canada's Western Grain Stabilization Program modifies the transmission of: (a) domestic yield variability to the foreign grain market and (b) foreign demand variability to the domestic grains market. With respect to (a), the program was found to aggravate international uncertainty only very slightly while with respect to (b) it was found to substantially reduce domestic uncertainty.Agricultural and Food Policy, International Relations/Trade,

Bridge number, Heegaard genus and non-integral Dehn surgery

We show there exists a linear function w: N->N with the following property. Let K be a hyperbolic knot in a hyperbolic 3-manifold M admitting a non-longitudinal S^3 surgery. If K is put into thin position with respect to a strongly irreducible, genus g Heegaard splitting of M then K intersects a thick level at most 2w(g) times. Typically, this shows that the bridge number of K with respect to this Heegaard splitting is at most w(g), and the tunnel number of K is at most w(g) + g-1.Comment: 76 page, 48 figures; referee comments incorporated and typos fixed; accepted at TAM

An Assessment of the Impact of Climate Change on Human Health in New Hampshire

Climate change threatens human health in many ways. The negative impacts of climate change on human health are likely to increase in both magnitude and frequency as the climate continues to change in response to ever increasing global emissions of heat-trapping gases released from a variety of human activities.The Centers for Disease Control and Prevention (CDC) Building Resilience Against Climate Effects (BRACE) framework provides guidance to states and cities to develop strategies and programs to confront the health implications of climate change. This report serves to address Steps 1 and 2 of the BRACE framework via an assessment of past and future climate change across New Hampshire combined with an assessment of the impact of climate change on human health. A key component of the BRACE framework is building resilience. In public health, resilience is a measure of a community’s ability to utilize available resources to respond to, withstand, and recover from adverse situations. More generally, people think of resilience as the ability to recover, persist, or thrive amid change. The New Hampshire Climate and Health Workgroup has tentatively developed the following definition: Resilience is the ability and capacity to anticipate, prepare for, respond to, and recover from significant threats with minimum damage to human health and well-being, the economy, and the environment. The importance of the way we plan our built environment—including land use, transportation, and water management decisions, as well as how we interact with our natural environment and preserve its life-supporting functions—must be emphasized as pivotal points of intersection as we develop climate adaptation strategies. Notably, a resilience-based approach to climate change adaptation should align with New Hampshire’s transformative State Health Improvement Plan. That plan underscores the importance of cross-sector collaboration and coordinated strategies to address the social and environmental determinants of health. These strategies not only support healthy communities for all New Hampshire residents, but they are also critically important for reducing health care costs and reducing the burden of disease

Trade Shocks and Labor Adjustment: Theory

We construct a dynamic, stochastic rational expectations model of labor reallocation within a trade model that is designed so that its key parameters can be estimated for trade policy analysis. A key feature is the presence of time-varying idiosyncratic moving costs faced by workers. As a consequence of these shocks: (i) Gross flows exceed net flows (an important feature of empirical labor movements); (ii) the economy features gradual and anticipatory adjustment to aggregate shocks; (iii) wage differentials across locations or industries can persist in the steady state; and (iv) the normative implications of policy can be very different from a model without idiosyncratic shocks, even when the aggregate behaviour of both models is similar. It is shown that the equilibrium solves a particular planner's problem, thus facilitating analytical results, econometric estimation, and simulation of the model for policy analysis.

Booms, Busts and Ripples in British Regional Housing Markets

We present and discuss an annual econometric model of regional house prices in Britain estimated over the period 1972 to 2003. The model, which consists of a system of inverted housing demand equations, is data consistent, incorporates spatial lags and errors, has some spatial coefficient heterogeneity, has a plausible long run solution and includes a full range of explanatory variables. We use our results to explain the periods of boom and bust and the ripple effect from London house prices to house prices elsewhere. We also address the issue of whether there has been a bubble in the British housing marketHouse Prices; Ripple Effect; Bubble