Interactions between toothbrush and toothpaste particles during simulated abrasive cleaning

Most people clean their teeth using toothpaste, consisting of abrasive particles in a carrier fluid, and a filament based toothbrush to remove plaque and stain. In order to optimise cleaning efficiency it is important to understand how toothbrush filaments, abrasive particles and fluid interact in a tooth cleaning contact. Work has been carried out to visualise, simulate, and model the processes in teeth cleaning. Laboratory cleaning contacts were created between a toothbrush and a transparent surface. Video and short duration flash photography were used to study the processes by which a toothbrush traps abrasive particles, loads them against the counterface, and removes material. Small abrasive particles tend to be trapped at the contact between the filament tip and the counterface, whilst larger particles are trapped by clumps of filaments or at the contact with the side of a bent filament. Measurements of brush friction force were recorded during cleaning for a range of operating conditions. The presence of abrasive particles in the cleaning mixture increased the coefficient of friction, but the absolute particle concentration showed a lesser effect. It is surmised that only a few particles carry any load and cause any abrasion; increasing the particle concentration does not directly increase the number of load bearing particles. Abrasive scratch tests were also carried out, using PMMA as a wearing substrate. The scratches produced during these tests were studied. The microscopy images were used to deduce how the filaments deflect and drag, and how particles are trapped by filaments and scratch the surface. Again, it was observed that few of the brush filaments loaded particles to produce scratches, and that when a filament changes direction of travel the trapped particle is lost. Results of these studies were used to develop both qualitative and quantitative models of the process by which material is removed in teeth cleaning. The quantitative model contains, by necessity, several empirical factors, but nonetheless predictions compare well with in vitro wear results from the literature. The results were also used to draw some broad conclusions on appropriate brushing techniques for optimum tooth cleaning

Mandatory Pre-Commitment Loss Limits: Six Years’ Experience Shows It Works

The Norwegian state owned company Norsk Tipping is a pioneer in the gambling indusrty with its secure player identification and mandatory registered play across all channels. Knowing who your player is and having a strong link between the player and his consumption of games across all channels (land based, EGM, web and mobile) is an important premise for having a credible responsible gaming platform. Norsk Tipping introduced in 2009 EGM’s with both pre commitment tools and maximum loss limits. In 2014 we introduced our Internet casino with probably the best responsible gambling platform in the world, including mandatory loss limits. The presentation will exemplify this with presenting the current responsible gaming platform for our Internet casino games, including the use of mandatory loss limits and the responsible gambling tool Playscan. The presentation will also show what our experiences with the responsible gambling platform and the use of loss limits are

Planning of Distributed Energy Systems with Parallel Infrastructures: A Case Study

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Insects join the consciousness fray

Klein & Barron\u27s review of recent insect neurobiology helps correct the impression that insect behavior is orchestrated without the benefit of central integrative mechanisms. Given their existence, the authors go on to ask whether these central mechanisms also feature the kind of integrative operations that support sentience, and propose that they do. Along the way they raise a number of conceptual and evidentiary issues of fundamental importance for the neuroscience of consciousness, allowing me to comment favorably on a number of them. I conclude by pointing to ways in which the conception of insect sentience they outline might be tested empirically

How not to move the line drawn on pain

In this second commentary I outline the inadequacy of Key\u27s responses to the many peer critiques of his thesis that have so far appeared in Animal Sentience. I illustrate with examples drawn from his response to my first commentary

Convergence of the restricted Nelder-Mead algorithm in two dimensions

The Nelder-Mead algorithm, a longstanding direct search method for unconstrained optimization published in 1965, is designed to minimize a scalar-valued function f of n real variables using only function values, without any derivative information. Each Nelder-Mead iteration is associated with a nondegenerate simplex defined by n+1 vertices and their function values; a typical iteration produces a new simplex by replacing the worst vertex by a new point. Despite the method's widespread use, theoretical results have been limited: for strictly convex objective functions of one variable with bounded level sets, the algorithm always converges to the minimizer; for such functions of two variables, the diameter of the simplex converges to zero, but examples constructed by McKinnon show that the algorithm may converge to a nonminimizing point. This paper considers the restricted Nelder-Mead algorithm, a variant that does not allow expansion steps. In two dimensions we show that, for any nondegenerate starting simplex and any twice-continuously differentiable function with positive definite Hessian and bounded level sets, the algorithm always converges to the minimizer. The proof is based on treating the method as a discrete dynamical system, and relies on several techniques that are non-standard in convergence proofs for unconstrained optimization.Comment: 27 page

Modèles d’équations simultanées pour variables endogènes fictives : une formulation par la théorie des jeux avec application à la participation au marché du travail

Les auteurs proposent une méthode inspirée par la théorie des jeux pour formuler des modèles d’équations simultanées et les appliquer à l’étude de la décision de deux personnes mariées de participer ou pas au marché du travail. Leur démarche se distingue par le fait que le modèle simultané utilise le résultat d’un jeu entre deux joueurs pour obtenir le comportement d’optimisation. Le concept d’équilibre retenu est celui de Nash. Par ailleurs, les auteurs démontrent que les conditions de cohérence logique, sont implicites dans les modèles d’équations simultanées avec glissement structurel, interdiraient en fait la simultanéité dans la modélisation du problème qu’ils considèrent. Par conséquent, leur modèle ne suppose aucune condition de cohérence logique dans les paramètres.A game theoretic approach for formulating simultaneous equations models for dummy endogenous variables is proposed and applied to a study of husband/wife labor force participation. A distinctive feature of our approach is that the simultaneous model is derived from optimizing behavior as an outcome of a game between two players. The equilibrium concept used is that of Nash. In addition, we show that the logical consistency conditions implied by usual simultaneous equation models with structural shift actually rules out simultaneity for the problem we consider; in our model, no logical consistency conditions are implied on the parameters

A Note on the Independence of Irrelevant Alternatives in Probabilistic Choice Models

The purpose of this note is to show that there is no necessary relationship between the independence of irrelevant alternatives (IIA) property and stochastic independence of the errors in probabilistic choice models

FLUORESCENCE AND CIRCULAR DICHROISM STUDIES ON THE PHYCOERYTHROCYANINS FROM THE CYANOBACTERIUM

Two phycoerythrocyanin (PEC) fractions have been obtained from the phycobilisomes of the cyanobac-terium Westiellopsis prolifica ARM 365. They have been characterized by absorption, fluorescence and circular dichroism spectroscopy. One of them is spectroscopically similar to a PEC trimer known from other organisms. Whereas efficient energy transfer from its violin (α-84) to the cyanin (β-84, 155) chromophores is efficient in the trimer (αβ it is impeded after dissociation to the monomer (α,β). A second fraction of PEC which we earlier termed PEC(X) (Maruthi Sai et al., Photochem. Photobiol. 55,119–124, 1992), exhibited the spectral properties similar to that of the α-subunit of PEC from Mastigocladus laminosus. With this highly photoactive fraction, the circular dichroism spectra of the violobilin chromophore in both photoreversible states were obtained

Integrirano planiranje opskrbe električnom energijom, plinom i toplinskom energijom u općini

This paper presents the results of a case study to investigate different alternatives for the energy supply to a municipality on the western coast of Norway. The following alternatives for energy supply are modelled and analysed: i) a district heating system with three different heat centrals, ii) a natural gas distribution system and iii) a low temperature distribution system. The case study is performed with the optimization model "eTransport" developed for the planning of local energy systems where several alternative energy carriers and technologies are considered simultaneously. The model minimizes the total energy system cost of meeting the demands of electricity, heating, cooling and gas within a geographical area over a given planning horizon. The model uses a detailed network representation of infrastructures to consider investments in distributed central stations, components, cables and pipelines. The object function includes investments, operating and environmental costs.Ovaj članak prezentira rezultate analize slučaja koja istražuje razne alternative za opskrbu energije jedne općine na zapadnoj obali Norveške. Sljedeće alternative za opskrbu energije su modelirane i analizirane: i) Područno grijanje s tri različite toplane ii) Distribucijski sustav za prirodni plin iii) Niskotemperaturni distribucijski sustav. Analiza slučaja je napravljena pomoću optimizacijskog modela „eTransport“ razvijenog za planiranje lokalnih energetskih sustava s primjenom raznih nosioca energije i tehnologija. Model minimizira cijenu sustava koji zadovoljava potrebu za električnom i toplinskom energijom, hlađenjem i plinom u nekom geografskom području za vrijeme planiranja. Model koristi detaljnu reprezentaciju mrežne infrastrukture da uzme u obzir investiciju u toplane, komponente, troškove okoliša i operativne troškove