Cultural geography: a survey of perceptions held by Cultural Geography Specialty Group members

As of the year 2000, the Cultural Geography Specialty Group of the Association of American Geographers had 465 members and ranked fourth overall in total membership within the association. Furthermore, cultural geographers had the second fastest growing specialty group between 1993 and 1998, after the Geographic Perspectives on Women specialty group. In spite of this demonstrated overwhelming appeal among geographers, to date, no one has systematically analyzed the subdiscipline of cultural geography to determine such things as its links to other aspects of the discipline, its major scholarly contributions, its most highly regarded publication outlets, its notable practitioners, and its most recognized departments. As the ranks of cultural geographers have swelled, the subdiscipline has become multifaceted. This article contextualizes and interprets the results of a survey sent to members of the 1998–1999 Cultural Geography Specialty Group. Outcomes include Louisiana State University and the University of Texas at Austin listed as offering the strongest cultural geography departments, Wilbur Zelinsky being deemed the subfield's most outstanding living practitioner, and the Annals of the Association of American Geographers named the journal that best meets cultural geographers’ needs

Conformal invariants measuring the best constants for Gagliardo-Nirenberg-Sobolev inequalities

We introduce a family of conformal invariants associated to a smooth metric measure space which generalize the relationship between the Yamabe constant and the best constant for the Sobolev inequality to the best constants for Gagliardo-Nirenberg-Sobolev inequalities $\|w\r|_q \leq C\|\nabla w\|_2^\theta \|w\|_p^{1-\theta}$. These invariants are constructed via a minimization procedure for the weighted scalar curvature functional in the conformal class of a smooth metric measure space. We then describe critical points which are also critical points for variations in the metric or the measure. When the measure is assumed to take a special form --- for example, as the volume element of an Einstein metric --- we use this description to show that minimizers of our invariants are only critical for certain values of $p$ and $q$. In particular, on Euclidean space our result states that either $p=2(q-1)$ or $q=2(p-1)$, giving a new characterization of the GNS inequalities whose sharp constants were computed by Del Pino and Dolbeault.Comment: 20 page

Constructing an Explicit AdS/CFT Correspondence with Cartan Geometry

An explicit AdS/CFT correspondence is shown for the Lie group $SO(4,2)$. The Lie symmetry structures allow for the construction of two physical theories through the tools of Cartan geometry. One is a gravitational theory that has anti-de Sitter symmetry. The other is also a gravitational theory but is conformally symmetric and lives on 8-dimensional biconformal space. These "extra" four dimensions have the degrees of freedom used to construct a Yang-Mills theory. The two theories, based on AdS or conformal symmetry, have a natural correspondence in the context of their Lie algebras alone where neither SUSY, nor holography, is necessary.Comment: 13 pages, 1 Tabl

Adaptive Gibbs samplers

We consider various versions of adaptive Gibbs and Metropolis- within-Gibbs samplers, which update their selection probabilities (and perhaps also their proposal distributions) on the fly during a run, by learning as they go in an attempt to optimise the algorithm. We present a cautionary example of how even a simple-seeming adaptive Gibbs sampler may fail to converge. We then present various positive results guaranteeing convergence of adaptive Gibbs samplers under certain conditions

Sharp weighted Sobolev trace inequalities and fractional powers of the Laplacian

We establish a family of sharp Sobolev trace inequalities involving the $W^{k,2}(\mathbb{R}_+^{n+1},y^a)$-norm. These inequalities are closely related to the realization of fractional powers of the Laplacian on $\mathbb{R}^n=\partial\mathbb{R}_+^{n+1}$ as generalized Dirichlet-to-Neumann operators associated to powers of the weighted Laplacian in upper half space, generalizing observations of Caffarelli--Silvestre and of Yang.Comment: 25 page

The Regulatory Reform Recommendations of the National Performance Review

Of ten recommendations Mr. Lubbers discusses, several were of particular interest. These include encouraging consensus-based rule making and ADR in enforcement, as well as ranking risks and improving regulatory science

An Evaluation of Herbicides for Control of Wild Oats in Barley: Efficacy, Phytotoxicity, and Barley Variety Susceptibility Studies

The control of wild oats (Avena Jatua L.) in Alaskan spring-planted barley was investigated in a series of experiments conducted from 1981-1984. Rates and times of applications of triallate (a preemergence, soil-incorporated herbicide), diclofop, barban, and difenzoquat (postemergence herbicides) were investigated in relation to control of wild oats and barley yield in 1981-1982. Because of very high wild oats populations. none of the herbicides controlled wild oats to the point of· allowing a barley harvest. Generally, wild oats were best controlled when herbicides were applied at an early growth stage and at the highest application rates. Control of wild oats with triallate was the same whether incorporated using parallel or perpendicular passes of a spike-tooth harrow. In 1983-84 both single herbicide treatments and combinations of herbicides were studied. Barban, diclofop, and difenzoquat were applied alone or with triallate applied in the fall or spring in emulsifiable concentrate or granular formulation. Wild oats population levels were lower in these 2 years, and applications of even single herbicides provided good wild oats control. Of the individual herbicides, diclofop provided the best control of wild oats. In general, when triallate was applied in conjunction with diclofop, barban, or difenzoquat, control of wild oats was better and higher barley yields were obtained than when a single wild oats herbicide was applied. When triallate was applied in the fall, the granular formulation provided better control of wild oats than the emulsifiable formulation. In a study of the response of eight barley varieties ('Eero', 'Paavo', 'Galt', 'Otra', 'Otal', 'Datal', 'Udal', 'Weal') to high rates and late times of application of the four herbicides, none of the varieties were differentially susceptible. Diclofop decreased heights of all varieties and decreased test weights