Sources of Epidemiological Equivocacy

Mr. Sly discusses five sources of uncertainty and ambiguity in health and medical research that can interfere with decision making

Badding Practise in Cennerfield?

Many years ago I heard a recorded lecture entitled Good Speech. I have forgotten the advice it contained, but if that speaker were here today I think he would have to start all over again. I think he would suggest a new approach to vowel sounds. A, E, I, O, U are our written vowels, but our sounding vowels are thirteen in number, and are used in this sentence

With Skirmish and Capricious Passagings: Ornithological and Poetic Discourse in the Nightingale Poems of Coleridge and Clare.

This paper is an exploration of the relationship between the poetic discourse of Romanticism, and the scientific discourse of ornithology, the emergence of which as a serious scientific discipline took place, according to Paul Lawrence Farber, between 1760 and 1850, thus spanning the lifetimes of High Romanticism’s prophet-figure, William Blake, and its patriarch, William Wordsworth. It is intended as a contribution to the developing field of ecocriticism, which has in recent years offered a new and challenging perspective on the representation and function of the natural world in literary texts in general and Romantic ones in particular, through full length general studies such as Jonathan Bates’s Song of the Earth (2000) and essays with a more specific focus, like John Rowlett’s ‘Ornithological Knowledge and Literary Understanding’ (1999), both of which have contributed much to my own understanding of and approach to my chosen texts

Uniqueness thresholds on trees versus graphs

Counter to the general notion that the regular tree is the worst case for decay of correlation between sets and nodes, we produce an example of a multi-spin interacting system which has uniqueness on the $d$-regular tree but does not have uniqueness on some infinite $d$-regular graphs.Comment: Published in at http://dx.doi.org/10.1214/07-AAP508 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Rapid Mixing of Gibbs Sampling on Graphs that are Sparse on Average

In this work we show that for every $d < \infty$ and the Ising model defined on $G(n,d/n)$, there exists a $\beta_d > 0$, such that for all $\beta < \beta_d$ with probability going to 1 as $n \to \infty$, the mixing time of the dynamics on $G(n,d/n)$ is polynomial in $n$. Our results are the first polynomial time mixing results proven for a natural model on $G(n,d/n)$ for $d > 1$ where the parameters of the model do not depend on $n$. They also provide a rare example where one can prove a polynomial time mixing of Gibbs sampler in a situation where the actual mixing time is slower than n \polylog(n). Our proof exploits in novel ways the local treelike structure of Erd\H{o}s-R\'enyi random graphs, comparison and block dynamics arguments and a recent result of Weitz. Our results extend to much more general families of graphs which are sparse in some average sense and to much more general interactions. In particular, they apply to any graph for which every vertex $v$ of the graph has a neighborhood $N(v)$ of radius $O(\log n)$ in which the induced sub-graph is a tree union at most $O(\log n)$ edges and where for each simple path in $N(v)$ the sum of the vertex degrees along the path is $O(\log n)$. Moreover, our result apply also in the case of arbitrary external fields and provide the first FPRAS for sampling the Ising distribution in this case. We finally present a non Markov Chain algorithm for sampling the distribution which is effective for a wider range of parameters. In particular, for $G(n,d/n)$ it applies for all external fields and $\beta < \beta_d$, where $d \tanh(\beta_d) = 1$ is the critical point for decay of correlation for the Ising model on $G(n,d/n)$.Comment: Corrected proof of Lemma 2.

Labor Matching Behavior in Open Economies and Trade Adjustment

This paper develops a model of costly trade and team production to examine the matching behavior of skilled workers in an open economy. Trade liberalization leads to a redistribution of rents across firms that differ in export status. When heterogeneous workers can bargain effectively and capture these rents, trade liberalization changes the supply of skilled production teams available for hire. Trade is shown to rationalize the matching behavior of workers, causing skill-upgrading within firms and infra-marginal improvements to firm-level productivity. Gains in productivity via skill-upgrading are distinct, and complementary, to the gains realized as low productivity firms exit and high productivity firms expand. All firms experience changes in skill composition, rather than just those on the margin of exit or exporting. Openness benefits those employed at exporting firms, however the likelihood of benefiting from trade is not necessarily increasing in skill. Wages in the open economy are tied to both worker skill and job type.Worker Heterogeneity, Wage Bargaining, Trade Adjustment, Matching

Skill Acquisition, Incentive Contracts and Jobs: Labor Market Adjustment to Trade

This paper examines how global integration influences worker behavior regarding skill acquisition, as well as firm behavior regarding incentive contracts and occupational diversity. The approach integrates several key components of international trade and the wage distribution in developed countries: namely heterogeneous firms, trade in similar goods, and performance payments to workers that endogenously obtain different skill levels. Greater trading opportunities reduce aggregate prices, causing workers to experience a greater marginal utility derived from income, as well as the skills that aid them in fulfilling performance contracts. Firms respond to skill accumulation among the labor force by adjusting the provision of incentive contracts, and the types of jobs they offer. Labor market adjustment to trade liberalization is characterized by a more steep, but less extensive, provision of incentive contracts among the labor force; higher overall wage inequality exhibiting a U-shaped differential; and job polarization across skill-groups.Job Polarization, Performance Pay, Trade Adjustment

Universality of cutoff for the Ising model

On any locally-finite geometry, the stochastic Ising model is known to be contractive when the inverse-temperature $\beta$ is small enough, via classical results of Dobrushin and of Holley in the 1970's. By a general principle proposed by Peres, the dynamics is then expected to exhibit cutoff. However, so far cutoff for the Ising model has been confirmed mainly for lattices, heavily relying on amenability and log Sobolev inequalities. Without these, cutoff was unknown at any fixed $\beta>0$, no matter how small, even in basic examples such as the Ising model on a binary tree or a random regular graph. We use the new framework of information percolation to show that, in any geometry, there is cutoff for the Ising model at high enough temperatures. Precisely, on any sequence of graphs with maximum degree $d$, the Ising model has cutoff provided that $\beta<\kappa/d$ for some absolute constant $\kappa$ (a result which, up to the value of $\kappa$, is best possible). Moreover, the cutoff location is established as the time at which the sum of squared magnetizations drops to 1, and the cutoff window is $O(1)$, just as when $\beta=0$. Finally, the mixing time from almost every initial state is not more than a factor of $1+\epsilon_\beta$ faster then the worst one (with $\epsilon_\beta\to0$ as $\beta\to 0$), whereas the uniform starting state is at least $2-\epsilon_\beta$ times faster.Comment: 26 pages, 2 figures. Companion paper to arXiv:1401.606