Nutritional and Defensive Chemistry of Three North American Ash Species: Possible Roles in Host Performance and Preference by Emerald Ash Borer Adults

Black ash (Fraxinus nigra), green ash (F. pennsylvanica), and white ash (F. americana) are the three most abundant ash species in the northeastern USA. We compared emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), adult performance and preference among seedlings of the three ash species, and then related performance and preference to foli- age nutritional quality and defensive compounds. Longevity of EAB adults reared on green and white ash was found to be greater than on black ash. EAB adult females also seemed to show feeding preference among the three species of ash trees because the total foliage area consumption was greater on green ash and white ash compared to black ash in dual-choice tests; however, the total mass of foliage consumed did not differ. The foliage of all ash species was high in nitrogen and in most macro- and micro-nutrients studied. The patterns of EAB performance and preference did not correspond to any of the individual chemical compounds tested (nitrogen, proteins, most macro- and micro-nutrients, or putative defensive compounds of ash seedlings). Never- theless, greater longevity of EAB adults on green and white ash compared to black ash was probably related to unbalanced nutrients (total nitrogen/total non-structural carbohydrate ratio) of black ash. Putative defensive compounds (i.e., phenolics and protease inhibitors) did not contribute to EAB longevity in this study, probably because (1) EAB adults were able to excrete most of these compounds and (2) their effects were alleviated by high nitrogen levels. More research is needed to elucidate the interactions of nitrogen and carbohydrate levels, and the interactions of nutrient balance and defensive plant allelochemicals on EAB performance and preference

The Conformal Bootstrap: Theory, Numerical Techniques, and Applications

Conformal field theories have been long known to describe the fascinating universal physics of scale invariant critical points. They describe continuous phase transitions in fluids, magnets, and numerous other materials, while at the same time sit at the heart of our modern understanding of quantum field theory. For decades it has been a dream to study these intricate strongly coupled theories nonperturbatively using symmetries and other consistency conditions. This idea, called the conformal bootstrap, saw some successes in two dimensions but it is only in the last ten years that it has been fully realized in three, four, and other dimensions of interest. This renaissance has been possible both due to significant analytical progress in understanding how to set up the bootstrap equations and the development of numerical techniques for finding or constraining their solutions. These developments have led to a number of groundbreaking results, including world record determinations of critical exponents and correlation function coefficients in the Ising and $O(N)$ models in three dimensions. This article will review these exciting developments for newcomers to the bootstrap, giving an introduction to conformal field theories and the theory of conformal blocks, describing numerical techniques for the bootstrap based on convex optimization, and summarizing in detail their applications to fixed points in three and four dimensions with no or minimal supersymmetry.Comment: 81 pages, double column, 58 figures; v3: updated references, minor typos correcte

An algorithm for series expansions based on hierarchical rate equations

We propose a computational method to obtain series expansions in powers of time for general dynamical systems described by a set of hierarchical rate equations. The method is generally applicable to problems in both equilibrium and nonequilibrium statistical mechanics such as random sequential adsorption, diffusion-reaction dynamics, and Ising dynamics. New result of random sequential adsorption of dimers on a square lattice is presented.Comment: LaTeX, 9 pages including 1 figur

Carving Out the Space of 4D CFTs

We introduce a new numerical algorithm based on semidefinite programming to efficiently compute bounds on operator dimensions, central charges, and OPE coefficients in 4D conformal and N=1 superconformal field theories. Using our algorithm, we dramatically improve previous bounds on a number of CFT quantities, particularly for theories with global symmetries. In the case of SO(4) or SU(2) symmetry, our bounds severely constrain models of conformal technicolor. In N=1 superconformal theories, we place strong bounds on dim(Phi*Phi), where Phi is a chiral operator. These bounds asymptote to the line dim(Phi*Phi) <= 2 dim(Phi) near dim(Phi) ~ 1, forbidding positive anomalous dimensions in this region. We also place novel upper and lower bounds on OPE coefficients of protected operators in the Phi x Phi OPE. Finally, we find examples of lower bounds on central charges and flavor current two-point functions that scale with the size of global symmetry representations. In the case of N=1 theories with an SU(N) flavor symmetry, our bounds on current two-point functions lie within an O(1) factor of the values realized in supersymmetric QCD in the conformal window.Comment: 60 pages, 22 figure

Conformal Bootstrap in the Regge Limit

We analytically solve the conformal bootstrap equations in the Regge limit for large N conformal field theories. For theories with a parametrically large gap, the amplitude is dominated by spin-2 exchanges and we show how the crossing equations naturally lead to the construction of AdS exchange Witten diagrams. We also show how this is encoded in the anomalous dimensions of double-trace operators of large spin and large twist. We use the chaos bound to prove that the anomalous dimensions are negative. Extending these results to correlators containing two scalars and two conserved currents, we show how to reproduce the CEMZ constraint that the three-point function between two currents and one stress tensor only contains the structure given by Einstein-Maxwell theory in AdS, up to small corrections. Finally, we consider the case where operators of unbounded spin contribute to the Regge amplitude, whose net effect is captured by summing the leading Regge trajectory. We compute the resulting anomalous dimensions and corrections to OPE coefficients in the crossed channel and use the chaos bound to show that both are negative.Comment: 40 pages, 1 figure; V2: Small corrections and clarification