Molecular mechanisms for a switch-like mating decision in Saccharomyces cerevisiae

Les changements évolutifs nous instruisent sur les nombreuses innovations permettant à chaque organisme de maximiser ses aptitudes en choisissant le partenaire approprié, telles que les caractéristiques sexuelles secondaires, les patrons comportementaux, les attractifs chimiques et les mécanismes sensoriels y répondant. L'haploïde de la levure Saccharomyces cerevisiae distingue son partenaire en interprétant le gradient de la concentration d'une phéromone sécrétée par les partenaires potentiels grâce à un réseau de protéines signalétiques de type kinase activées par la mitose (MAPK). La décision de la liaison sexuelle chez la levure est un événement en "tout–ourien", à la manière d'un interrupteur. Les cellules haploïdes choisissent leur partenaire sexuel en fonction de la concentration de phéromones qu’il produit. Seul le partenaire à proximité sécrétant des concentrations de phéromones égales ou supérieures à une concentration critique est retenu. Les faibles signaux de phéromones sont attribués à des partenaires pouvant mener à des accouplements infructueux. Notre compréhension du mécanisme moléculaire contrôlant cet interrupteur de la décision d'accouplement reste encore mince. Dans le cadre de la présente thèse, je démontre que le mécanisme de décision de la liaison sexuelle provient de la compétition pour le contrôle de l'état de phosphorylation de quatre sites sur la protéine d'échafaudage Ste5, entre la MAPK, Fus3, et la phosphatase,Ptc1. Cette compétition résulte en la dissociation de type « intérupteur » entre Fus3 et Ste5, nécessaire à la prise de décision d'accouplement en "tout-ou-rien". Ainsi, la décision de la liaison sexuelle s'effectue à une étape précoce de la voie de réponse aux phéromones et se produit rapidement, peut-être dans le but de prévenir la perte d’un partenaire potentiel. Nous argumentons que l'architecture du circuit Fus3-Ste5-Ptc1 génère un mécanisme inédit d'ultrasensibilité, ressemblant à "l'ultrasensibilité d'ordre zéro", qui résiste aux variations de concentration de ces protéines. Cette robustesse assure que l'accouplement puisse se produire en dépit de la stochasticité cellulaire ou de variations génétiques entre individus.Je démontre, par la suite, qu'un évènement précoce en réponse aux signaux extracellulaires recrutant Ste5 à la membrane plasmique est également ultrasensible à l'augmentation de la concentration de phéromones et que cette ultrasensibilité est engendrée par la déphosphorylation de huit phosphosites en N-terminal sur Ste5 par la phosphatase Ptc1 lorsqu'elle est associée à Ste5 via la protéine polarisante, Bem1. L'interférence dans ce mécanisme provoque une perte de l'ultrasensibilité et réduit, du même coup, l'amplitude et la fidélité de la voie de réponse aux phéromones à la stimulation. Ces changements se reflètent en une réduction de la fidélité et de la précision de la morphologie attribuable à la réponse d'accouplement. La polarisation dans l'assemblage du complexe protéique à la surface de la membrane plasmique est un thème général persistant dans tous les organismes, de la bactérie à l'humain. Un tel complexe est en mesure d'accroître l'efficacité, la fidélité et la spécificité de la transmission du signal. L'ensemble de nos découvertes démontre que l'ultrasensibilité, la précision et la robustesse de la réponse aux phéromones découlent de la régulation de la phosphorylation stoichiométrique de deux groupes de phosphosites sur Ste5, par la phosphatase Ptc1, un groupe effectuant le recrutement ultrasensible de Ste5 à la membrane et un autre incitant la dissociation et l'activation ultrasensible de la MAPK terminal Fus3. Le rôle modulateur de Ste5 dans la décision de la destinée cellulaire étend le répertoire fonctionnel des protéines d'échafaudage bien au-delà de l'accessoire dans la spécificité et l'efficacité des traitements de l'information. La régulation de la dynamique des caractères signal-réponse à travers une telle régulation modulaire des groupes de phosphosites sur des protéines d'échafaudage combinées à l'assemblage à la membrane peut être un moyen général par lequel la polarisation du destin cellulaire est obtenue. Des mécanismes similaires peuvent contrôler les décisions cellulaires dans les organismes complexes et peuvent être compromis dans des dérèglements cellulaires, tel que le cancer. Finalement, sur un thème relié, je présente la découverte d'un nouveau mécanisme où le seuil de la concentration de phéromones est contrôlé par une voie sensorielle de nutriments, ajustant, de cette manière, le point prédéterminé dans lequel la quantité et la qualité des nutriments accessibles dans l'environnement déterminent le seuil à partir duquel la levure s'accouple. La sous-unité régulatrice de la kinase à protéine A (PKA),Bcy1, une composante clé du réseau signalétique du senseur aux nutriments, interagit directement avec la sous-unité α des petites protéines G, Gpa1, le premier effecteur dans le réseau de réponse aux phéromones. L'interaction Bcy1-Gpa1 est accrue lorsque la cellule croit en présence d'un sucre idéal, le glucose, diminuant la concentration seuil auquel la décision d'accouplement est activée. Compromettre l'interaction Bcy1-Gpa1 ou inactiver Bcy1 accroît la concentration seuil nécessaire à une réponse aux phéromones. Nous argumentons qu'en ajustant leur sensibilité, les levures peuvent intégrer le stimulus provenant des phéromones au niveau du glucose extracellulaire, priorisant la décision de survie dans un milieu pauvre ou continuer leur cycle sexuel en choisissant un accouplement.

Contact Sensing: A Sequential Decision Approach to Sensing Manipulation Contact

This paper describes a new statistical, model-based approach to building a contact state observer. The observer uses measurements of the contact force and position, and prior information about the task encoded in a graph, to determine the current location of the robot in the task configuration space. Each node represents what the measurements will look like in a small region of configuration space by storing a predictive, statistical, measurement model. This approach assumes that the measurements are statistically block independent conditioned on knowledge of the model, which is a fairly good model of the actual process. Arcs in the graph represent possible transitions between models. Beam Viterbi search is used to match measurement history against possible paths through the model graph in order to estimate the most likely path for the robot. The resulting approach provides a new decision process that can be use as an observer for event driven manipulation programming. The decision procedure is significantly more robust than simple threshold decisions because the measurement history is used to make decisions. The approach can be used to enhance the capabilities of autonomous assembly machines and in quality control applications.

Behind the decision making of the KFC coffee campaign, can KFC win the coffee market in UK?�

KFC, the chain fast-food restaurants in UK, planed to launched coffee products through campaigns. There are two main reasons for KFC to make the decision. The first one is KFC tried to promote its coffee products with KFC A.M. breakfast plan and it failed at last. The second reason is that KFC needs extension points of interest. The financial condition of KFC has been steady but no breakthrough growth. It has been showed that there is enormous potential of “fast-drink” market in UK. After the success of KFC “Krushems” series, it is reasonable for the company launched coffee products. However, KFC also faced to many challenges to win the market. Compare to the main competitor of McDonald’s, KFC’s quantity of restaurants is far too less. Moreover, KFC has a brand limitation that focuses more family than single urban. The dominant competitors are another challenge KFC need to manage. To sum up, KFC has to win these challenges to be a bigger player in UK coffee market.

A formalization for multi-agent decision support in cooperative environments. A framework for situated agents

La tesis propone un marco de trabajo para el soporte de la toma de decisiones adecuado para soportar la ejecución distribuida de acciones cooperativas en entornos multi-agente dinámicos y complejos. Soporte para la toma de decisiones es un proceso que intenta mejorar la ejecución de la toma de decisiones en escenarios cooperativos. Este proceso ocurre continuamente en la vida diaria. Los humanos, por ejemplo, deben tomar decisiones acerca de que ropa usar, que comida comer, etc. En este sentido, un agente es definido como cualquier cosa que está situada en un entorno y que actúa, basado en su observación, su interpretación y su conocimiento acerca de su situación en tal entorno para lograr una acción en particular.Por lo tanto, para tomar decisiones, los agentes deben considerar el conocimiento que les permita ser consientes en que acciones pueden o no ejecutar. Aquí, tal proceso toma en cuenta tres parámetros de información con la intención de personificar a un agente en un entorno típicamente físico. Así, el mencionado conjunto de información es conocido como ejes de decisión, los cuales deben ser tomados por los agentes para decidir si pueden ejecutar correctamente una tarea propuesta por otro agente o humano. Los agentes, por lo tanto, pueden hacer mejores decisiones considerando y representando apropiadamente tal información. Los ejes de decisión, principalmente basados en: las condiciones ambientales, el conocimiento físico y el valor de confianza del agente, provee a los sistemas multi-agente un confiable razonamiento para alcanzar un factible y exitoso rendimiento cooperativo.Actualmente, muchos investigadores tienden a generar nuevos avances en la tecnología agente para incrementar la inteligencia, autonomía, comunicación y auto-adaptación en escenarios agentes típicamente abierto y distribuidos. En este sentido, esta investigación intenta contribuir en el desarrollo de un nuevo método que impacte tanto en las decisiones individuales como colectivas de los sistemas multi-agente. Por lo tanto, el marco de trabajo propuesto ha sido utilizado para implementar las acciones concretas involucradas en el campo de pruebas del fútbol robótico. Este campo emula los juegos de fútbol real, donde los agentes deben coordinarse, interactuar y cooperar entre ellos para solucionar tareas complejas dentro de un escenario dinámicamente cambiante y competitivo, tanto para manejar el diseño de los requerimientos involucrados en las tareas como para demostrar su efectividad en trabajos colectivos. Es así que los resultados obtenidos tanto en el simulador como en el campo real de experimentación, muestran que el marco de trabajo para el soporte de decisiones propuesto para agentes situados es capaz de mejorar la interacción y la comunicación, reflejando en un adecuad y confiable trabajo en equipo dentro de entornos impredecibles, dinámicos y competitivos. Además, los experimentos y resultados también muestran que la información seleccionada para generar los ejes de decisión para situar a los agentes, es útil cuando tales agentes deben ejecutar una acción o hacer un compromiso en cada momento con la intención de cumplir exitosamente un objetivo colectivo. Finalmente, algunas conclusiones enfatizando las ventajas y utilidades del trabajo propuesto en la mejora del rendimiento colectivo de los sistemas multi-agente en situaciones tales como tareas coordinadas y asignación de tareas son presentadas.

An economic decision support tool for simulating paratuberculosis control strategies in a UK suckler beef herd

A dynamic, deterministic, economic simulation model was developed to estimate the costs and benefits of controlling Mycobacterium avium subsp. paratuberculosis (Johne's disease) in a suckler beef herd. The model is intended as a demonstration tool for veterinarians to use with farmers. The model design process involved user consultation and participation and the model is freely accessible on a dedicated website. The 'user-friendly' model interface allows the input of key assumptions and farm specific parameters enabling model simulations to be tailored to individual farm circumstances. The model simulates the effect of Johne's disease and various measures for its control in terms of herd prevalence and the shedding states of animals within the herd, the financial costs of the disease and of any control measures and the likely benefits of control of Johne's disease for the beef suckler herd over a 10-year period. The model thus helps to make more transparent the 'hidden costs' of Johne's in a herd and the likely benefits to be gained from controlling the disease. The control strategies considered within the model are 'no control', 'testing and culling of diagnosed animals', 'improving management measures' or a dual strategy of 'testing and culling in association with improving management measures'. An example 'run' of the model shows that the strategy 'improving management measures', which reduces infection routes during the early stages, results in a marked fall in herd prevalence and total costs. Testing and culling does little to reduce prevalence and does not reduce total costs over the 10-year period.

Gaining acceptability for the Bayesian decision-theoretic approach in dose-escalation studies

There has recently been increasing demand for better designs to conduct first-into-man dose-escalation studies more efficiently, more accurately and more quickly. The authors look into the Bayesian decision-theoretic approach and use simulation as a tool to investigate the impact of compromises with conventional practice that might make the procedures more acceptable for implementation. Copyright © 2005 John Wiley & Sons, Ltd.

Deconstruction plan assessment using multi-criteria decision-making methods

The purpose of this paper is to present two multi-criteria decision-making models, including an Analytic Hierarchy Process (AHP) model and an Analytic Network Process (ANP) model for the assessment of deconstruction plans and to make a comparison between the two models with an experimental case study. Deconstruction planning is under pressure to reduce operation costs, adverse environmental impacts and duration, in the meanwhile to improve productivity and safety in accordance with structure characteristics, site conditions and past experiences. To achieve these targets in deconstruction projects, there is an impending need to develop a formal procedure for contractors to select a most appropriate deconstruction plan. Because numbers of factors influence the selection of deconstruction techniques, engineers definitely need effective tools to conduct the selection process. In this regard, multi-criteria decision-making methods such as AHP have been adopted to effectively support deconstruction technique selection in previous researches. in which it has been proved that AHP method can help decision-makers to make informed decisions on deconstruction technique selection based on a sound technical framework. In this paper, the authors present the application and comparison of two decision-making models including the AHP model and the ANP model for deconstruction plan assessment. The paper concludes that both AHP and ANP are viable and capable tools for deconstruction plan assessment under the same set of evaluation criteria. However, although the ANP can measure relationship among selection criteria and their sub-criteria, which is normally ignored in the AHP, the authors also indicate that whether the ANP model can provide a more accurate result should be examined in further research.

Saccadic eye movements as an index of perceptual decision-making

One of the most common decisions we make is the one about where to move our eyes next. Here we examine the impact that processing the evidence supporting competing options has on saccade programming. Participants were asked to saccade to one of two possible visual targets indicated by a cloud of moving dots. We varied the evidence which supported saccade target choice by manipulating the proportion of dots moving towards one target or the other. The task was found to become easier as the evidence supporting target choice increased. This was reflected in an increase in percent correct and a decrease in saccade latency. The trajectory and landing position of saccades were found to deviate away from the non-selected target reflecting the choice of the target and the inhibition of the non-target. The extent of the deviation was found to increase with amount of sensory evidence supporting target choice. This shows that decision-making processes involved in saccade target choice have an impact on the spatial control of a saccade. This would seem to extend the notion of the processes involved in the control of saccade metrics beyond a competition between visual stimuli to one also reflecting a competition between options.

When does ignorance make us smart? Additional factors guiding heuristic inference

“Fast & frugal” heuristics represent an appealing way of implementing bounded rationality and decision-making under pressure. The recognition heuristic is the simplest and most fundamental of these heuristics. Simulation and experimental studies have shown that this ignorance-driven heuristic inference can prove superior to knowledge based inference (Borges, Goldstein, Ortman & Gigerenzer, 1999; Goldstein & Gigerenzer, 2002) and have shown how the heuristic could develop from ACT-R’s forgetting function (Schooler & Hertwig, 2005). Mathematical analyses also demonstrate that, under certain conditions, a “less-is-more effect” will always occur (Goldstein & Gigerenzer, 2002). The further analyses presented in this paper show, however, that these conditions may constitute a special case and that the less-is-more effect in decision-making is subject to the moderating influence of the number of options to be considered and the framing of the question.

Decision theory and real estate development: a note on uncertainty

Real estate development appraisal is a quantification of future expectations. The appraisal model relies upon the valuer/developer having an understanding of the future in terms of the future marketability of the completed development and the future cost of development. In some cases the developer has some degree of control over the possible variation in the variables, as with the cost of construction through the choice of specification. However, other variables, such as the sale price of the final product, are totally dependent upon the vagaries of the market at the completion date. To try to address the risk of a different outcome to the one expected (modelled) the developer will often carry out a sensitivity analysis on the development. However, traditional sensitivity analysis has generally only looked at the best and worst scenarios and has focused on the anticipated or expected outcomes. This does not take into account uncertainty and the range of outcomes that can happen. A fuller analysis should include examination of the uncertainties in each of the components of the appraisal and account for the appropriate distributions of the variables. Similarly, as many of the variables in the model are not independent, the variables need to be correlated. This requires a standardised approach and we suggest that the use of a generic forecasting software package, in this case Crystal Ball, allows the analyst to work with an existing development appraisal model set up in Excel (or other spreadsheet) and to work with a predetermined set of probability distributions. Without a full knowledge of risk, developers are unable to determine the anticipated level of return that should be sought to compensate for the risk. This model allows the user a better understanding of the possible outcomes for the development. Ultimately the final decision will be made relative to current expectations and current business constraints, but by assessing the upside and downside risks more appropriately, the decision maker should be better placed to make a more informed and “better”.

Decision making for HVAC&R system selection for a typical office building in the UK

Demands for thermal comfort, better indoor air quality together with lower environmental impacts have had ascending trends in the last decade. In many circumstances, these demands could not be fully covered through the soft approach of bioclimatic design like optimisation of the building orientation and internal layout. This is mostly because of the dense urban environment and building internal energy loads. In such cases, heating, ventilation, air-conditioning and refrigeration (HVAC&R) systems make a key role to fulfill the requirements of indoor environment. Therefore, it is required to select the most proper HVAC&R system. In this study, a robust decision making approach for HVAC&R system selection is proposed. Technical performance, economic aspect and environmental impacts of 36 permutations of primary and secondary systems are taken into account to choose the most proper HVAC&R system for a case study office building. The building is a representative for the dominant form of office buildings in the UK. Dynamic performance evaluation of HVAC&R alternatives using TRNSYS package together with life cycle energy cost analysis provides a reliable basis for decision making. Six scenarios broadly cover the decision makers' attitudes on HVAC&R system selection which are analysed through Analytical Hierarchy Process (AHP). One of the significant outcomes reveals that, despite both the higher energy demand and more investment requirements associated with compound heating, cooling and power system (CCHP); this system is one of the top ranked alternatives due to the lower energy cost and C02 emissions. The sensitivity analysis reveals that in all six scenarios, the first five top ranked alternatives are not changed. Finally, the proposed approach and the results could be used by researchers and designers especially in the early stages of a design process in which all involved bodies face the lack of time, information and tools for evaluation of a variety of systems.

Making robust policy decision using global biodiversity indicators

In order to influence global policy effectively, conservation scientists need to be able to provide robust predictions of the impact of alternative policies on biodiversity and measure progress towards goals using reliable indicators. We present a framework for using biodiversity indicators predictively to inform policy choices at a global level. The approach is illustrated with two case studies in which we project forwards the impacts of feasible policies on trends in biodiversity and in relevant indicators. The policies are based on targets agreed at the Convention on Biological Diversity (CBD) meeting in Nagoya in October 2010. The first case study compares protected area policies for African mammals, assessed using the Red List Index; the second example uses the Living Planet Index to assess the impact of a complete halt, versus a reduction, in bottom trawling. In the protected areas example, we find that the indicator can aid in decision-making because it is able to differentiate between the impacts of the different policies. In the bottom trawling example, the indicator exhibits some counter-intuitive behaviour, due to over-representation of some taxonomic and functional groups in the indicator, and contrasting impacts of the policies on different groups caused by trophic interactions. Our results support the need for further research on how to use predictive models and indicators to credibly track trends and inform policy. To be useful and relevant, scientists must make testable predictions about the impact of global policy on biodiversity to ensure that targets such as those set at Nagoya catalyse effective and measurable change.

Do good deeds make bad people?

According to the so-called ‘self-licensing effect’, committing to a virtuous act in a preceding choice may lead to behave less virtuously in the succeeding decision. Consequently, well-intentioned policies can lead to overall counter-productive effects by licensing people to behave badly in related behaviors. On the other side, motivational crowding theory argues that constraining people to adopt a desirable behavior can backfire. We use of a classroom experiment to test whether a regulatory framework to incentivize individuals to adopt pro-environmental behavior generate similar spillovers in terms of licensing effect than a non-regulatory framework. We show that the way the good deed is caused doesn’t seem to influence the licensing effect. Nevertheless, we found that business- and environmental-orientated majors react adversely to the regulatory framework. We show that environmental-orientated students exhibit higher intrinsically motivations than business-orientated ones. Accordingly, we suggest that the licensing effect is more likely to arise when the preceding ‘virtuous’ act is freely chosen (respectively regulatory caused) for non-intrinsically (respectively intrinsically) motivated individuals.

Decision Tree Classification Model In Water Supply Network

With the service life of water supply network (WSN) growth, the growing phenomenon of aging pipe network has become exceedingly serious. As urban water supply network is hidden underground asset, it is difficult for monitoring staff to make a direct classification towards the faults of pipe network by means of the modern detecting technology. In this paper, based on the basic property data (e.g. diameter, material, pressure, distance to pump, distance to tank, load, etc.) of water supply network, decision tree algorithm (C4.5) has been carried out to classify the specific situation of water supply pipeline. Part of the historical data was used to establish a decision tree classification model, and the remaining historical data was used to validate this established model. Adopting statistical methods were used to access the decision tree model including basic statistical method, Receiver Operating Characteristic (ROC) and Recall-Precision Curves (RPC). These methods has been successfully used to assess the accuracy of this established classification model of water pipe network. The purpose of classification model was to classify the specific condition of water pipe network. It is important to maintain the pipeline according to the classification results including asset unserviceable (AU), near perfect condition (NPC) and serious deterioration (SD). Finally, this research focused on pipe classification which plays a significant role in maintaining water supply networks in the future.

How national culture on consumers' decision-making styles: a comparative study among Americans, Brazilians, Chinese, and japanese in the purchase of cell phones.

The influence of the national culture on consumer decision-making styles is investigated using a sample of Americans, Brazilians, Chinese, and Japanese consumers who have purchased a cell phone in the past three years. To make the research possible, a survey was used as a method of data collection. It relates Hofstede’s cultural classification typology with Sproles and Kendall’s consumer style inventory (CSI). The multivariate analysis of variance (MANOVA) results indicate six decision-making styles together with other consumer behavioral characteristics that can be used to distinguish and profile consumers who purchase cell phones. Empirical findings reveal that among Americans, Brazilians, and Japanese; Americans are the most quality conscious, brand conscious, innovative, and hedonistic shoppers; Brazilians are the most loyal, and Japanese, the most confused by overchoice consumers. Conceptual contributions and managerial implications are discussed.