191 research outputs found

    Optimal rate of convergence for nonparametric change-point estimators for nonstationary sequences

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    Let (Xi)i=1,...,n(X_i)_{i=1,...,n} be a possibly nonstationary sequence such that L(Xi)=Pn\mathscr{L}(X_i)=P_n if i≤nθi\leq n\theta and L(Xi)=Qn\mathscr{L}(X_i)=Q_n if i>nθi>n\theta, where 0<θ<10<\theta <1 is the location of the change-point to be estimated. We construct a class of estimators based on the empirical measures and a seminorm on the space of measures defined through a family of functions F\mathcal{F}. We prove the consistency of the estimator and give rates of convergence under very general conditions. In particular, the 1/n1/n rate is achieved for a wide class of processes including long-range dependent sequences and even nonstationary ones. The approach unifies, generalizes and improves on the existing results for both parametric and nonparametric change-point estimation, applied to independent, short-range dependent and as well long-range dependent sequences.Comment: Published in at http://dx.doi.org/10.1214/009053606000001596 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    The Structural Complexity of (Bi0.5Na0.5)TiO3-BaTiO3 as Revealed by Raman Spectroscopy

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    The structural phase diagram of the Pb-free ferroelectric (Na1/2Bi1/2)1-xBaxTiO3 (NBT-BT), x<0.1, has been explored by Raman spectroscopy at temperatures from 10 to 470 K. The data provide clear evidence for a proposed temperature-independent morphotropic phase boundary at x \approx 0.055. However, there is no evidence for a structural phase transition across T \approx 370 K for x > 0.055, where bulk-property anomalies appear to signal a transition to a nonpolar or antiferroelectric phase. The results identify that the phase above 370 K shows short-range ionic displacements that are identical to those in the long-range-ordered phase below 370 K. These conclusions provide a natural interpretation of the weak piezoelectric response in this system and have important implications for the search for Pb-free piezoelectrics.Comment: 21 pages, 5 figure

    Development of a Mindful-Eating Intervention Program among Third Through Fifth Grade Elementary School Children and Their Parents

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    The prevalence of obesity among children in the United States is a major health concern and is associated with increased health risks. The goal of this intervention was to develop and pilot test strategies based on mindful eating practices that foster healthy eating behaviors among elementary school children and their families. Mindful eating practice engages all of ones senses and has been shown to decrease impulsive food decisions and increase awareness of hunger and fullness cues. Using Experiential Learning Theory (ELT), class interventions and take-home activities were developed to teach mindful eating strategies to Hispanic and non-Hispanic 3rd through 5th grade elementary school children and their parents. The results of this research will: 1) contribute to the scientific literature regarding the impact of mindful eating practice on children’s eating behavior, 2) provide an alternate strategy for weight loss and management among children, and 3) provide parents and teachers with the knowledge and skills necessary to promote mindful eating among children and families

    The politics of rurality (editorial)

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    Guest edited special issue of Landscape Research

    Identifying the optimal donor for natural killer cell adoptive therapy to treat paediatric B- and T-cell acute lymphoblastic leukaemia.

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    Objectives: Natural killer (NK) cells are an attractive source of cells for an 'off the shelf' cellular therapy because of their innate capacity to target malignant cells, and ability to be transferred between donors and patients. However, since not all NK cells are equally effective at targeting cancer, selecting the right donor for cellular therapy is critical for the success of the treatment. Recently, cellular therapies utilising NK cells from cytomegalovirus (CMV)-seropositive donors have been explored. However, whether these NK cells are the best source to treat paediatric acute lymphoblastic leukaemia (ALL) remains unclear. Methods: Using a panel of patient-derived paediatric B- and T-ALL, we assessed the ability of NK cells from 49 healthy donors to mount an effective functional response against these two major subtypes of ALL. Results: From this cohort, we have identified a pool of donors with superior activity against multiple ALL cells. While these donors were more likely to be CMV+, we identified multiple CMVneg donors within this group. Furthermore, NK cells from these donors recognised B- and T-ALL through different activating receptors. Dividing functional NK cells into 29 unique subsets, we observed that within each individual the same NK cell subsets dominated across all ALL cells. Intriguingly, this occurred despite the ALL cells in our panel expressing different combinations of NK cell ligands. Finally, we can demonstrate that cellular therapy products derived from these superior donors significantly delayed leukaemia progression in preclinical models of ALL. Conclusions: We have identified a pool of superior donors that are effective against a range of ALL cells, representing a potential pool of donors that can be used as an adoptive NK cell therapy to treat paediatric ALL

    Opportunities for organoids as new models of aging.

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    The biology of aging is challenging to study, particularly in humans. As a result, model organisms are used to approximate the physiological context of aging in humans. However, the best model organisms remain expensive and time-consuming to use. More importantly, they may not reflect directly on the process of aging in people. Human cell culture provides an alternative, but many functional signs of aging occur at the level of tissues rather than cells and are therefore not readily apparent in traditional cell culture models. Organoids have the potential to effectively balance between the strengths and weaknesses of traditional models of aging. They have sufficient complexity to capture relevant signs of aging at the molecular, cellular, and tissue levels, while presenting an experimentally tractable alternative to animal studies. Organoid systems have been developed to model many human tissues and diseases. Here we provide a perspective on the potential for organoids to serve as models for aging and describe how current organoid techniques could be applied to aging research
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