The Computational Complexity of the Game of Set and its Theoretical Applications

The game of SET is a popular card game in which the objective is to form Sets using cards from a special deck. In this paper we study single- and multi-round variations of this game from the computational complexity point of view and establish interesting connections with other classical computational problems. Specifically, we first show that a natural generalization of the problem of finding a single Set, parameterized by the size of the sought Set is W-hard; our reduction applies also to a natural parameterization of Perfect Multi-Dimensional Matching, a result which may be of independent interest. Second, we observe that a version of the game where one seeks to find the largest possible number of disjoint Sets from a given set of cards is a special case of 3-Set Packing; we establish that this restriction remains NP-complete. Similarly, the version where one seeks to find the smallest number of disjoint Sets that overlap all possible Sets is shown to be NP-complete, through a close connection to the Independent Edge Dominating Set problem. Finally, we study a 2-player version of the game, for which we show a close connection to Arc Kayles, as well as fixed-parameter tractability when parameterized by the number of rounds played

Efficacy of Chlorhexidine Varnish for the Prevention of Adult Caries: A Randomized Trial

The Prevention of Adult Caries Study, an NIDCR-funded multicenter, double-blind, randomized clinical trial, enrolled 983 adults (aged 18-80 yrs) at high risk for developing caries (20 or more intact teeth and 2 or more lesions at screening) to test the efficacy of a chlorhexidine diacetate 10% weight per volume (w/v) dental coating (CHX). We excluded participants for whom the study treatment was contraindicated or whose health might affect outcomes or ability to complete the study. Participants were randomly assigned to receive either the CHX coating (n = 490) or a placebo control (n = 493). Coatings were applied weekly for 4 weeks and a fifth time 6 months later. The primary outcome (total net D1-2FS increment) was the sum of weighted counts of changes in tooth surface status over 13 months. We observed no significant difference between the two treatment arms in either the intention-to-treat or per-protocol analyses. Analysis of 3 protocol-specified secondary outcomes produced similar findings. This trial failed to find that 10% (w/v) chlorhexidine diacetate coating was superior to placebo coating for the prevention of new caries (Clinicaltrials.gov registration number NCT00357877)

The non-adoption of supply chain management

This is an Accepted Manuscript of an article published by Taylor & Francis in Construction Management and Economics on 10th October 2013, available online: http://wwww.tandfonline.com/10.1080/01446193.2013.830186.Largely taken for granted within the UK construction sector has been a view that supply chain management theory is robust, relevant and reliable. As such it has formed a substantial aspect of previous and contemporary policy and government funded research. Despite this, the general view of its development and diffusion over the last 15 years within the construction industry has been problematic. Coincidentally, prevailing debates within the supply chain management academic community point to the lack of unified theory, models of diffusion and strong connections to organization theory. Using Straussian grounded theory, iterations between data and organization theory provided a fresh perspective on the development and diffusion of supply chain management in construction. This inductive research provided contextually rich explanations for development and diffusion that explicitly connected with and drew upon robust, relevant and reliable theories of institutions, innovation diffusion, triads, quasifirms and mechanisms of organizational governance. These explanations challenge the simplistic assumption that chains and networks of organizations are holistically managed and controlled by any single organization or institution in the construction industry. The debate therefore shifts away from proselytizing supply chain management towards research that explores the rigour, relevance and reliability of supply chain management assumptions in construction. The gap between industry practice and policy is exposed and the question is posed: to what extent policy and practice do, or should, constitute a recursive relationship.© 2013 Taylor & Francis

Model Discrimination of Radical Desorption Kinetics in Emulsion Polymerisation

Analysis of published experimental data on monomeric radical diffusion in the emulsion polymerisation of styrene shows that it can be quantitatively described equally well by non-equilibrium diffusion from particles, where all parameters are derived from properties of the discrete phase, or by steady-state diffusion where all parameters are derived from properties of the continuous phase. The non-equilibrium model better describes an observed experimental trend to a reduced desorption rate coefficient at higher weight fraction of polymer in the particles. The theoretical upper bound of the non-equilibrium model is also higher than the theoretical upper bound of the steady-state model allowing fits to experimental data which must be discarded as anomalous in the continuous phase model

Chain transfer to monomer and polymer in radical polymerisation of vinyl neo-decanoate

Molecular weight distributions of poly(vinyl neo-decanoate) produced by the bulk polymerization of the monomer to low conversions were investigated to obtain values of the rate constants for the chain transfer to monomer (C M ). The value of C M of 7.5(±0.6)x10 -4was obtained from a logarithmic plot of the number distribution at 5,25, and 50°C which suggests that the activation energy for chain transfer is on the order of 20-25 kJ mol . These plots were linear between the number and weight-average degrees of polymerization, but not over the whole molecular weight range for which a significant signal was observed in the gel permeation chromatography (GPC) trace. Modeling suggests that the deviations observed at high molecular weights can be explained by branching of the chains through chain transfer to the polymer, with a branching density as low as 10-5 , without affecting the slope at low values of the number of monomer unit, N. This deviation from the expected distribution of linear chains was used to estimate the branching densities at low conversion.ion

Synthesis of flocculant aids for cane sugar juice clarification - Part III: Dependence of clarification efficiency on the composition of copolymers of acrylamide and trimethylammoniumethyl(meth)acrylate chlorides [Synthese von flockungshilfsmitteln für die saftreinigung in der rohrzuckerindustrie - Teil III: Abhängigkeit des saftreinigungseffektes von der zusammensetzung der copolymere von acrylamiden und trimethylammonium-ethyl(meth)acrylat-chloriden]

Copolymers of acrylamide with quaternary ammonium cationic monomers trimethylammoniumethylacrylate chloride (TMAEAC) and trimethylammoniumethylmethacrylate chloride (TMAEMAC) were prepared, characterized, and tested as flocculant aids to facilitate the clarification of primary cane sugar juice in the presence of an anionic flocculant. The effectiveness of these copolymers was compared with selected commercially available cationic copolymers. At dosages of 10 and 40 mg/kg, certain of the synthesized polymers were found to be more effective in reducing juice turbidity and increasing juice settling rate than commercial polymers. The differences between the effectiveness of TMAEAC and TMAEMAC copolymers were not marked, with the intrinsic viscosity of the copolymers (related to the size of the random polymer coil in solution) likely to be a more important parameter than copolymer composition. Clarification was found to be generally more effective and rapid if the flocculant aid was added after rather than before addition of calcium saccharate to the primary sugar juice. The results obtained are consistent with the flocculant aid operating by a bridging mechanism, and support the hypothesis that a separate population of particles, smaller than those targeted by the anionic flocculant, primarily interact with the flocculant aid

Flocculation and sedimentation of cane sugar juice particles with cationic homo- and copolymers

Rapid flocculation and sedimentational of suspended particles in primary cane sugar juice is achieved using a high molecular weight anionic polymer flocculant. This work reports on efforts to enhance the performance of an anionic flocculant by the addition of cationic polymers. Homopolymers of poly(trimethylammonium ethyl methacrylate chloride) (TMAEMAC) and cationic copolymers of poly(trimethylammonium ethyl acrylate chloride) (TMAEAC) and acrylamide were synthesized and their performance, to enhance the flocculation and sedimentation of cane sugar juice particles, was evaluated by turbidity and setting rate measurements. The charge-patch mechanism best explains the performance of the homopolymers, whereas the action of the copolymers is attributed to the bridging mechanism. The results of this work indicate that the copolymers are more effective than the homopolymers to aid flocculation and sedimentation of the cane sugar juice particles, and that the best-performing polymers are those that act by the bridging mechanism. Addition of increased amounts of anionic flocculant did not confer an improvement, suggesting that the cationic bridging flocculant targets a different population of particles that is largely responsible for the residual turbidity

Shear-induced coagulation in emulsion polymerization systems

http://trove.nla.gov.au/work/1806460