Searching for Plans Using a Hierarchy of Learned Macros and Selective Reuse

This research presents a new approach to improving the performance of a macro planner: selective reuse. In macro planning, reuse can result in poorer performance than when planning with only primitive operators, a phenomenon that has been called the utility problem. The utility problem arises because the benefits of reuse are outweighed by the cost of retrieving a macro to reuse and the cost of searching through the larger search space caused by considering reuse candidates. Selective reuse contains the expansion of the search space by limiting the number of reuse candidates considered and limits the search required by considering only those reuse candidates that entail no additional work. Previously, performance improvement in a macro planner has been possible only by selective learning. Unlike selective learning, selective reuse never overlooks a learning opportunity that might have value in future problem solving. This research developed a polynomial-order retrieval method which reduces the cost of retrieving a reuse candidate likely to save search. A macro planner (HINGE) was implemented to explore selective reuse. To improve the probability of beneficial reuse. HINGE searches in a space of plans using a hierarchically-structured search method that provides multiple opportunities for reuse

Comparison of robust coupling techniques for planar waveguide immunosensors

Journal ArticleWe have analyzed and fabricated two different coupling schemes to meet the requirements for a convenient means of coupling into a planar waveguide immunosensor that is relatively insensitive to beam alignment. These are the "launch" coupler and the grating coupler. Each possesses advantages and disadvantages, depending mainly on die thickness (mode number) of the waveguide to be illuminated. For example, the launch coupler is best suited to a thick (highly multimode) waveguide and is less efficient for a thin (few mode) guide. Our experimental results verify predictions of a ray theory developed to give coupling efficiency for a variety of coupling parameters

Evanescent coupling in a waveguide fluoroimmunosensor

Journal ArticleA key factor in the analysis of evanescently-coupled optical sensors, such as the planar waveguide immunosensor analyzed here, is the efficiency of coupling between the optical waveguide modes and the fluorescent sources located on the surface of the waveguide. This is an important parameter in determining the sensor's sensitivity to the analyte. We calculate this efficiency for several different sensor configurations using the finite-difference time-domain (FDTD) numerical technique, and find that the efficiency of one-way coupling can vary widely depending upon the fluorescent source polarization, phase, and distance from the surface, as well as the waveguide mode number and thickness. In particular, we find that when the layer containing the fluorescent molecules is uniform in refractive index, the coupling efficiency is larger than when the local environment possesses an irregular index

Dispersion effects in fiber optic interferometry

Journal ArticleAn extended analysis of the effects of uncompensated fiber dispersion on the fringe visibility of a fiber optic interferometer is developed, with particular emphasis on stellar interferometry. Both material and waveguide dispersion for single-mode, polarization-preserving fibers are considered. It is found that dispersion causes the fringe visibility curve to broaden, decrease in contrast, shift its centroid location, and in some cases become asymmetric. It is also sh own that when the interferometer is operated at wavelengths near 1300 nm, cancellation of second-order material and waveguide dispersion significantly improves the fringe visibility. The theoretical results are verified experimentally at both 672 nm and 1307 nm using a fiber optic Mach-Zehnder interferometer

Bidding in Common Value Auctions: How the Commercial Construction Industry Corrects for the Winner's Curse

Experienced construction industry executives suffer from a winner's curse in laboratory common- value auction markets. (Dyer et al. 1989). This paper identifies essential differences between field environments and the economic theory underlying the laboratory markets that account for the executives' success in the field and a winner's curse in the lab. These are (1) industry-specific mechanisms which enable contractors to escape the winner's curse even when they bid too low, (2) learned, industry-specific evaluative processes which enable experienced contractors to avoid the winner's curse in the first place, and (3) important private value elements that underlie bidding. Also identified are a number of industry-specific bidding characteristics whose evoluation can be explained using modern auction theory. Lessons are drawn regarding the use of experimental methods in economics.Auctions, construction industry, winner's curse, field data, experiments

The extracellular matrix and the immune system : A mutually dependent relationship

Acknowledgments: We are very grateful to our colleagues at the Wellcome Centre for Cell-Matrix Research and the Lydia Becker Institute for Immunology and Inflammation for many stimulating discussions. We would especially like to thank A. Day, D. Thornton, R. Lennon, A. MacDonald, and T. Hardingham and the anonymous referees for critical review of the manuscript. Figures have been drawn in BioRender. Funding: This work was supported by MRC-UK grant MR/V011235/1 (J.E.A.) and Wellcome Trust grants 106898/A/15/Z (J.E.A.), 218570/Z/19/Z (D.P.D.), and 203128/A/16/Z (T.E.S., D.P.D., and J.E.A.).Peer reviewedPostprin

Evaluation of the Efficacy of the Stress Protein Response as a Biochemical Water Quality Biomonitoring Method

The stress protein response (SPR) is a conserved and ubiquitous mechanism that enables cells to tolerate a wide variety of environmental insults. This response involves the preferential synthesis of an array of proteins with different molecular weights. These proteins perform a variety of functions, such as protein folding, multimeric protein assembly, steroid receptor binding, and heme catabolism. To evaluate the potential use of the SPR as a biomonitoring tool, a stepwise plan was utilized that proceeded through various physical and chemical laboratory exposures and culminated with a field validation study. The goals of the laboratory exposures were threefold: (1) determine the time required for induction of the SPR; (2) determine the dose-responsiveness of the SPR; and (3) compare the increased syntheses and accumulations of stress proteins to classical toxicological endpoints (i.e. percent mortality, LC50, LC1, etc)

On the switch Markov chain for perfect matchings

We study a simple Markov chain, the switch chain, on the set of all perfect matchings in a bipartite graph. This Markov chain was proposed by Diaconis, Graham and Holmes as a possible approach to a sampling problem arising in Statistics. We ask: for which hereditary classes of graphs is the Markov chain ergodic and for which is it rapidly mixing? We provide a precise answer to the ergodicity question and close bounds on the mixing question. We show for the first time that the mixing time of the switch chain is polynomial in the case of monotone graphs, a class that includes examples of interest in the statistical setting

Shrink film patterning by craft cutter: complete plastic chips with high resolution/high-aspect ratio channel

This paper presents a rapid, ultra-low-cost approach to fabricate microfluidic devices using a polyolefin shrink film and a digital craft cutter. The shrinking process (with a 95% reduction in area) results in relatively uniform and consistent microfluidic channels with smooth surfaces, vertical sidewalls, and high aspect ratio channels with lateral resolutions well beyond the tool used to cut them. The thermal bonding of the layers results in strongly bonded devices. Complex microfluidic designs are easily designed on the fly and protein assays are also readily integrated into the device. Full device characterization including channel consistency, optical properties, and bonding strength are assessed in this technical note