Bayesian D-Optimal Choice Designs for Mixtures

__Abstract__ Consumer products and services can often be described as mixtures of ingredients. Examples are the mixture of ingredients in a cocktail and the mixture of different components of waiting time (e.g., in-vehicle and out-of-vehicle travel time) in a transportation setting. Choice experiments may help to determine how the respondents' choice of a product or service is affected by the combination of ingredients. In such studies, individuals are confronted with sets of hypothetical products or services and they are asked to choose the most preferred product or service from each set. However, there are no studies on the optimal design of choice experiments involving mixtures. We propose a method for generating an optimal design for such choice experiments. To this end, we first introduce mixture models in the choice context and next present an algorithm to construct optimal experimental designs, assuming the multinomial logit model is used to analyze the choice data. To overcome the problem that the optimal designs depend on the unknown parameter values, we adopt a Bayesian D-optimal design approach. We also consider locally D-optimal designs and compare the performance of the resulting designs to those produced by a utility-neutral (UN) approach in which designs are based on the assumption that individuals are indifferent between all choice alternatives. We demonstrate that our designs are quite different and in general perform better than the UN designs

A New Multivariate Product Growth Model

To examine cross-country diffusion of new products, marketing researchers have to rely on a multivariate product growth model. We put forward such a model, and show that it is a natural extension of the original Bass (1969) model. We contrast our model with currently in use multivariate models and we show that inference is much easier and interpretation is straightforward. In fact, parameter estimation can be done using standard commercially available software. We illustrate the benefits of our model relative to other models in simulation experiments. An application to a three-country CD sales series shows the merits of our model in practice

Implementation of semi-autonomous vehicle for environmental feedback

In a world marked by war and terrorism, the Department of Defense has found an increasing need for the use of unmanned ground vehicles (UGV) to facilitate the safety of its soldiers in the battlefield. UGVs can be used for scouting and surveying enemy territory instead of placing soldiers at risk. In response to this matter, the objective of this report is to propose a design for a microcontroller based vehicle that can give the user feedback on the environment. We propose to implement a camera sensor on a vehicle that will be used to track and follow a marked line on the ground. Additional information including direction and speed of the vehicle will be recorded using magnetometer and accelerometer sensors, respectively. The direction information is needed to give the user an idea of the vehicle’s orientation. The speed information is needed to control the response of the motors based upon the type of ground topography (e.g. sloped surface vs. flat surface). The goal of the project is to implement the combination of these three sensors (camera, magnetometer, and accelerometer) for better control of the vehicle in its environment. The intended deliverable will be a small vehicle powered by a rechargeable battery and controlled by the ATMega16 microcontroller. The vehicle will also contain the accelerometer, magnetometer, and camera sensors

A connectivity ­based parcellation of the left dorsal premotor cortex

peer reviewe

Dying in cyberworld: violent video games extinguished children’s death concept and attitude

Death is often a taboo topic in society, especially among the Chinese community. Most of the violent video games spread immoral values of life and death. Hence deformed death concept and death attitude are easily moulded in children particularly without proper supervision from parents. The misconception of death concept and death attitude can manipulate primary school children’s attitudes towards death which gradually might lead children to harm themselves or others. This study is aimed at identifying the relationship between violent video games and children’s death concept and death attitude (Fear of death, Death avoidance, Approach Acceptance, Escape Acceptance). The differences between the level of exposure to violent video games towards children’s death concept and death attitude are also carried out in this study. A total of 397 data was collected from Malaysian Chinese schoolchildren between 10 to 12 years of age by using the purposive sampling method. Instruments used in this study consist of demographic information, Death Attitude Media Violence Exposure. The study showed that a high level of exposure towards violent video games had a significant negative correlation with death concept and fear of death, whilst significantly positive correlation with escape acceptance. The result of the independent samples t-test showed that children with high exposure to violent video games had lower death concept and fear of death and a higher level of escape acceptance. Further research is needed to explore the death concept and attitude among children as technology has become an inseparable part of human beings in the 4th Industrial Revolutio

Beware of black swans: Taking stock of the description–experience gap in decision under uncertainty

Uncertainty pervades most aspects of life. From selecting a new technology to choosing a career, decision makers rarely know in advance the exact outcomes of their decisions. Whereas the consequences of decisions in standard decision theory are explicitly described (the decision from description (DFD) paradigm), the consequences of decisions in the recent decision from experience (DFE) paradigm are learned from experience. In DFD, decision makers typically overrespond to rare events. That is, rare events have more impact on decisions than their objective probabilities warrant (overweighting). In DFE, decision makers typically exhibit the opposite pattern, underresponding to rare events. That is, rare events may have less impact on decisions than their objective probabilities warrant (underweighting). In extreme cases, rare events are completely neglected, a pattern known as the “Black Swan effect.” This contrast between DFD and DFE is known as a description–experience gap. In this paper, we discuss several tentative interpretations arising from our interdisciplinary examination of this gap. First, while a source of underweighting of rare events in DFE may be sampling error, we observe that a robust description–experience gap remains when these factors are not at play. Second, the residual description–experience gap is not only about experience per se but also about the way in which information concerning the probability distribution over the outcomes is learned in DFE. Econometric error theories may reveal that different assumed error structures in DFD and DFE also contribute to the gap

Flavored Gauge-Mediation

The messengers of Gauge-Mediation Models can couple to standard-model matter fields through renormalizable superpotential couplings. These matter-messenger couplings generate generation-dependent sfermion masses and are therefore usually forbidden by discrete symmetries. However, the non-trivial structure of the standard-model Yukawa couplings hints at some underlying flavor theory, which would necessarily control the sizes of the matter-messenger couplings as well. Thus for example, if the doublet messenger and the Higgs have the same properties under the flavor theory, the resulting messenger-lepton couplings are parametrically of the same order as the lepton Yukawas, so that slepton mass-splittings are similar to those of minimally-flavor-violating models and therefore satisfy bounds on flavor-violation, with, however, slepton mixings that are potentially large. Assuming that fermion masses are explained by a flavor symmetry, we construct viable and natural models with messenger-lepton couplings controlled by the flavor symmetry. The resulting slepton spectra are unusual and interesting, with slepton mass-splittings and mixings that may be probed at the LHC. In particular, since the new contributions are typically negative, and since they are often larger for the first- and second-generation sleptons, some of these examples have the selectron or the smuon as the lightest slepton, with mass splittings of a few to tens of GeV.Comment: 16 pages v2: Explicit expressions (which are not needed in the analysis) for the pure Yukawa contributions removed. There was an error in some of these expressions in v1. References adde

Genetic regulators of cytokine responses upon BCG vaccination in children from West Africa

Genetic variation is a key factor influencing cytokine production capacity, but which genetic loci regulate cytokine production before and after vaccination, particularly in African population is unknown. Here, we aimed to identify single-nucleotide polymorphisms (SNPs) controlling cytokine responses (cQTLs) after microbial stimulation in infants of West-African ancestry, comprising of low-birth-weight neonates randomized to bacillus Calmette–Guérin (BCG) vaccine-at-birth (intervention) or to the usual delayed BCG (control). Genome-wide cytokine QTL mapping revealed 12 independent cQTLs loci, of which the LINC01082-LINC00917 locus influenced more than half of the cytokine-stimulation pairs assessed. Furthermore, nine distinct cQTLs were found among infants randomized to BCG. Functional validation confirmed that several complement genes affect cytokine response after BCG vaccination. We observed a limited overlap of common cQTLs between the West-African infants and cohorts of Western European individuals. These data reveal strong population-specific genetic effects on cytokine production and may indicate new opportunities for therapeutic intervention and vaccine development in African populations.</p

A Geographically-Restricted but Prevalent Mycobacterium tuberculosis Strain Identified in the West Midlands Region of the UK between 1995 and 2008

Background: We describe the identification of, and risk factors for, the single most prevalent Mycobacterium tuberculosis strain in the West Midlands region of the UK.Methodology/Principal Findings: Prospective 15-locus MIRU-VNTR genotyping of all M. tuberculosis isolates in the West Midlands between 2004 and 2008 was undertaken. Two retrospective epidemiological investigations were also undertaken using univariable and multivariable logistic regression analysis. The first study of all TB patients in the West Midlands between 2004 and 2008 identified a single prevalent strain in each of the study years (total 155/3,056 (5%) isolates). This prevalent MIRU-VNTR profile (32333 2432515314 434443183) remained clustered after typing with an additional 9-loci MIRU-VNTR and spoligotyping. The majority of these patients (122/155, 79%) resided in three major cities located within a 40 km radius. From the apparent geographical restriction, we have named this the "Mercian" strain. A multivariate analysis of all TB patients in the West Midlands identified that infection with a Mercian strain was significantly associated with being UK-born (OR = 9.03, 95% CI = 4.56-17.87, p 65 years old (OR = 0.25, 95% CI = 0.09-0.67, p < 0.01). A second more detailed investigation analyzed a cohort of 82 patients resident in Wolverhampton between 2003 and 2006. A significant association with being born in the UK remained after a multivariate analysis (OR = 9.68, 95% CI = 2.00-46.78, p < 0.01) and excess alcohol intake and cannabis use (OR = 6.26, 95% CI = 1.45-27.02, p = .01) were observed as social risk factors for infection.Conclusions/Significance: The continued consistent presence of the Mercian strain suggests ongoing community transmission. Whilst significant associations have been found, there may be other common risk factors yet to be identified. Future investigations should focus on targeting the relevant risk groups and elucidating the biological factors that mediate continued transmission of this strain

Prediction and Optimal Scheduling of Advertisements in Linear Television

Advertising is a crucial component of marketing and an important way for companies to raise awareness of goods and services in the marketplace. Advertising campaigns are designed to convey a marketing image or message to an audience of potential consumers and television commercials can be an effective way of transmitting these messages to a large audience. In order to meet the requirements for a typical advertising order, television content providers must provide advertisers with a predetermined number of impressions in the target demographic. However, because the number of impressions for a given program is not known a priori and because there are a limited number of time slots available for commercials, scheduling advertisements efficiently can be a challenging computational problem. In this case study, we compare a variety of methods for estimating future viewership patterns in a target demographic from past data. We also present a method for using those predictions to generate an optimal advertising schedule that satisfies campaign requirements while maximizing advertising revenue