Densities, spectral densities and modality

This paper considers the problem of specifying a simple approximating density function for a given data set (x_1,...,x_n). Simplicity is measured by the number of modes but several different definitions of approximation are introduced. The taut string method is used to control the numbers of modes and to produce candidate approximating densities. Refinements are introduced that improve the local adaptivity of the procedures and the method is extended to spectral densities.Comment: Published by the Institute of Mathematical Statistics (http://www.imstat.org) in the Annals of Statistics (http://www.imstat.org/aos/) at http://dx.doi.org/10.1214/00905360400000036

Breakdown and Groups II

The notion of breakdown point was introduced by Hampel (1968, 1971) and has since played an important role in the theory and practice of robust statistics. In Davies and Gather (2004) it was argued that the success of the concept is connected to the existence of a group of transformations on the sample space and the linking of breakdown and equivariance. For example the highest breakdown point of any translation equivariant functional on the real line is 1/2 whereas without equivariance considerations the highest breakdown point is the trivial upper bound of 1. --

Robust Statistics

The first example involves the real data given in Table 1 which are the results of an interlaboratory test. The boxplots are shown in Fig. 1 where the dotted line denotes the mean of the observations and the solid line the median. We note that only the results of the Laboratories 1 and 3 lie below the mean whereas all the remaining laboratories return larger values. In the case of the median, 7 of the readings coincide with the median, 24 readings are smaller and 24 are larger. A glance at Fig. 1 suggests that in the absence of further information the Laboratories 1 and 3 should be treated as outliers. This is the course which we recommend although the issues involved require careful thought. For the moment we note simply that the median is a robust statistic whereas the mean is not. --

Confidence sets and non-parametric regression

--Nonparametric regression , shape regularization , confidence bounds

Connecting resources in online learning environments

This article highlights considerations for connecting resources in Online Learning Environments (OLEs). Extensive human, information, learning, and technical resources are needed to produce and manage comprehensive OLEs. The requirements and considerations for each of these resources are unique, but they should be viewed mainly as interrelated and connected to each other. Basic considerations for resources-based OLEs are discussed in this article, however future research is needed to explore the complexity of these resources and how they can be optimized for the effective delivery and management of online learning environments

Constructing a regular histogram : a comparison of methods

Even for a well-trained statistician the construction of a histogram for a given real-valued set is a sifficult problem. It is even more difficult to construct a fully automatic procedure which specifies the number and widths of the binss in a satisfactory manner for a wide range of data sets. In this paper we compare several histogram construction methods by means of a simulation study. The study includes plug-in methods, cross-validation, penalized maximum likehood and the taut string procedure. Their performance on different test beds is measured by the Hellinger distance and the ability to identify the modes of the underlying density. --regular histogramm,model selection,penalized likehood,taut-string

Regulation of Akt and Wnt signalling by the dopamine D2 receptor and metabotropic glutamate receptor 2/3

Akt and the Wnt pathway, two cascades that regulate GSK-3, have been implicated in schizophrenia and antipsychotic drug action. Although it is known that antipsychotic drugs alleviate psychosis by blocking the dopamine D2 receptor (D2DR) and that metabotropic glutamate receptor 2/3 (mGluR2/3) agonists may improve some of the symptoms of schizophrenia, it is unclear if both classes of drugs exert their effects through Akt, GSK-3 and/or the Wnt pathway or if changes in these pathways are mediated through the D2DR and mGluR2/3 respectively. In addition to antipsychotics, mood stabilizers and antidepressants also target GSK-3, suggesting that there must be something unique in the way GSK-3 is targeted by antipsychotics since neither mood stabilizers nor antidepressants alleviate psychosis. The current study examined whether Akt and the Wnt pathway are regulated by the D2DR and mGluR2/3 and investigated the role of Akt and Dvl-3, a key activator in the Wnt pathway, in regulating GSK-3 in the rat brain. The study also compared the effects of antipsychotic, mood stabilizers and antidepressants on Akt and Wnt pathway proteins to determine if antipsychotics have unique effects on these signalling proteins. Results showed that raclopride (D2DR antagonist) regulated Akt and the Wnt pathway via Dvl-3 and the response was identical to antipsychotic treatment. Administration of the mGluR2/3 agonist, LY379268 also targeted Akt and the Wnt pathway and induced a similar response as antipsychotics. In addition, repeated amphetamine treatment, an established animal model for the positive symptoms of schizophrenia, quinpirole (D2DR agonist) and LY341495 (mGluR2/3 antagonist) induced similar changes in Akt and Wnt signalling that parallel alterations reported in schizophrenia. Furthermore, systemic inhibition of GSK-3 was able to attenuate the increase in locomotion induced by LY341495, a behavioural measure that models the positive symptoms of schizophrenia. The study also showed that clozapine and haloperidol (antipsychotics) induced a common Wnt response that was not mimicked by the mood stabilizers or antidepressants tested but that all neuropsychiatric drugs tested induced changes in Akt. Collectively the data shows that the Wnt pathway is regulated specifically by drugs with antipsychotic properties and may represent a novel target for pharmaceutical intervention

Doctor of Philosophy

dissertationCaring communities support the healthy growth of young people by fostering caring one-on-one relationships as well as a sense of connectedness to the overall community. Through these mechanisms, caring communities are critical context;s for positive youth development. Day camps may be uniquely situated serve as caring communities, particularly through effective program design and staff implementation. Little is known about the ways these processes foster positive youth outcomes, especially youths' perceptions of a caring community. Therefore, the purpose of this study was to examine the effects of program design and staff implementation on campers' sense of day camp as a caring community. A quasi-experimental, mixed repeated-measures design was used to assess the impact of program design and staff implementation on campers' sense of caring community. Caring one-on-one relationships between campers and camp staff facilitate a positive camper climate which in turn promotes an overall sense of connectedness to camp. Caring and connectedness, then, were the dependent variables in this study. The independent variables were a staff training targeting program design and a training targeting implementation. The design-based training oriented camp staff to a set of Caring Activities that staff members incorporated at camp. The implementation-based training focused solely on staff members' ethic of care. Three municipal day camps participated in this study, two of which received the trainings and one was a comparison condition. Campers from all three sites completed the instrumentation three times during the summer: Time One assessed baseline levels of caring and connectedness and Times Two and Three assessed the impact of each of the training sessions. Analysis of the dependent variables revealed three notable findings. First, a profile analysis of caring revealed a significant time by treatment interaction, which suggested that campers' sense of camp as a caring community depends on whether their counselors received staff training or not. A follow-up planned comparison on caring revealed a significant difference between treatment and nontreatment conditions at Time Two but not at Time Three. Profile analysis of connectedness revealed a significant but negative trend over time in both treatment and nontreatment conditions. The findings and their implications for caring communities are discussed

Confessional Biblical Preaching in the Face of Whiteness: Challenging the Preacher’s Understanding of White Supremacy

This thesis addresses the need for preachers to hear the voices of people of color, to hear the “prophets in the streets,” specifically African-Americans, and to have their eyes opened to their own white privilege and role in white supremacy. This thesis argues that this is an important step in preachers finding their confessional voices for preaching before they can begin to help the individual members of those congregations become aware of their individual and collective white privilege and role in white supremacy. With the help of black clergy a “Twin Cities Pilgrimage” was created. This involved learning the stories of locations (sacred places both hopeful and painful), for the black community in the Twin Cities, hearing Scripture at the locations and the white preachers preaching from those same Scriptures the following Sunday