Bayesian inference for a discretely observed stochastic kinetic model

The ability to infer parameters of gene regulatory networks is emerging as a key problem in systems biology. The biochemical data are intrinsically stochastic and tend to be observed by means of discrete-time sampling systems, which are often limited in their completeness. In this paper we explore how to make Bayesian inference for the kinetic rate constants of regulatory networks, using the stochastic kinetic Lotka-Volterra system as a model. This simple model describes behaviour typical of many biochemical networks which exhibit auto-regulatory behaviour. Various MCMC algorithms are described and their performance evaluated in several data-poor scenarios. An algorithm based on an approximating process is shown to be particularly efficient.     

Explaining Cooperation: How Resource Interdependence, Goal Congruence, and Trust Affect Joint Actions in Policy Implementation

A perennial problem when political decisions are to be implementedis how to make authorities work together. Previous researchshows that resource interdependence, goal congruence, and mutualtrust increase interorganizational cooperation. In this article,it is argued that interaction effects must also be consideredin order to fully understand how these variables affect cooperation.The study is based on 203 dyads of Swedish Public EmploymentService offices and municipalities in 2003. I find that mutualtrust is necessary if goal congruence is to increase cooperationbetween these agencies. Furthermore, mutual trust only has apositive effect if organizations have similar objectives. However,trust is not required for resource interdependence to affectcooperation, and the effect of trust is not dependent on theorganizations' mutual dependence. The results imply that trustand goal congruence must exist simultaneously in order to promotejoint actions. Thus, if a management strategy aimed at increasingcooperation only focuses on the organizations' objectives orthe level of trust between them, it will fail. An importantlesson for future research is that including interaction termsin the analysis improves our understanding of interorganizationalcooperation.     

Asthma Patients' Activities and Air Pollution: A Semiparametric Censored Regression Analysis

Asthma patients' health status may be especially sensitive to some types of air pollution, but the evidence on this is mixed. We explore the effects of ground-level ozone on asthma patient's activities, breaking apart the usual aggregated category of leisure into indoor and outdoor activities, and differentiating those by whether the activities were active or inactive. Applying the semiparametric censored estimation method we demonstrate that even though the period over which activities were observed was relatively low in ozone levels, there is a significant impact of ozone on a few activities. The (non-ozone) economic and demographic variables in the model play significant roles in explaining the allocation of time among seven activities, suggesting the suitability of the approach for other household decision-making contexts.     

The Development of Affect Specificity in Infants' Use of Emotion Cues

This study examined the emergence of affect specificity in infancy. In this study, infants received verbal and facial signals of 2 different, negatively valenced emotions (fear and sadness) as well as neutral affect via a television monitor to determine if they could make qualitative distinctions among emotions of the same valence. Twenty 12‐ to 14‐month‐olds and 20 16‐ to 18‐month‐olds were examined. Results suggested that younger infants showed no evidence of referential specificity, as they responded similarly to both the target and distracter toys, and showed no evidence of affect specificity, showing no difference in play between affect conditions. Older infants, in contrast, showed evidence both of referential and affect specificity. With respect to affect specificity, 16‐ to 18‐month‐olds touched the target toy less in the fear condition than in the sad condition and showed a larger proportion of negative facial expressions in the sad condition versus the fear condition. These findings suggest a developmental emergence after 15 months of age for affect specificity in relating emotional messages to objects.     

Some observations on the history of large philanthropic foundations in Britain and the United States

Large philanthropic foundations such as those which first developed in the United States in the late nineteenth and early twentieth century had four characteristics: (a) the aim of contributing to the public good; (b) applying science and scientific method to human affairs, interpreting science broadly; (c) using great wealth to pursue these purposes; and (d) seeking public recognition of their charitable status in doing so. Between 1870 and 1930 the large foundation emerged as a major social institution, and under the influence of their officers began to be major patrons of applied social science for public policy purposes. Critics of foundations have charged that they were private bodies without external accountability; they were secretive, undemocratic, unrepresentative and indeed pillars of the ruling class. Nevertheless, foundations have exercised a disproportionate influence upon public policy research and have sought to apply fundamental knowledge to tackling social problems. They represent the institutionalisation of knowledge-based social engineering.     

A Process for Incorporating Comparative Risk into Environmental Policymaking in Louisiana

The goal of Louisiana's 1990–1991 comparative risk project, also called the Louisiana Environmental Action Plan (LEAP), was to incorporate risk assessment into state environmental planning and policymaking. Scientists, government officials, and citizens were brought together to estimate the relative risk to human health, natural resources, and quality of life posed by 33 selected environmental issues. The issues were then ranked according to their relative estimated risks. It was hoped that this ranking of "comparative risks" would enable state policymakers to target the most important environmental problems and allocate scarce public resources more rationally and efficiently. As a result of the project, the governor issued an Executive Order forming a permanent Public Advisory Committee to continue this type of comparative risk assessment in Louisiana.     

Native American drinking: a neglected subject of study and research

Although Native Americans are plagued by high rates of alcoholism, violence, suicide and early death, these social and clinical problems are usually given little more than cursory treatment in textbooks. A content analysis of twenty-six textbooks on alcoholism and substance misuse revealed that only four provided a detailed discussion of Native American drinking. Greater attention needs to be given to the cultural, psychological, and biological issues of drinking and drunkenness among this special population.     

Domains of convergence for the EM algorithm: a cautionary tale in a location estimation problem

The EM algorithm is a popular method for maximizing a likelihood in the presence of incomplete data. When the likelihood has multiple local maxima, the parameter space can be partitioned into domains of convergence, one for each local maximum. In this paper we investigate these domains for the location family generated by the t-distribution. We show that, perhaps somewhat surprisingly, these domains need not be connected sets. As an extreme case we give an example of a domain which consists of an infinite union of disjoint open intervals. Thus the convergence behaviour of the EM algorithm can be quite sensitive to the starting point.