Dirichlet Process Hidden Markov Multiple Change-point Model

This paper proposes a new Bayesian multiple change-point model which is based on the hidden Markov approach. The Dirichlet process hidden Markov model does not require the specification of the number of change-points a priori. Hence our model is robust to model specification in contrast to the fully parametric Bayesian model. We propose a general Markov chain Monte Carlo algorithm which only needs to sample the states around change-points. Simulations for a normal mean-shift model with known and unknown variance demonstrate advantages of our approach. Two applications, namely the coal-mining disaster data and the real United States Gross Domestic Product growth, are provided. We detect a single change-point for both the disaster data and US GDP growth. All the change-point locations and posterior inferences of the two applications are in line with existing methods.Comment: Published at http://dx.doi.org/10.1214/14-BA910 in the Bayesian Analysis (http://projecteuclid.org/euclid.ba) by the International Society of Bayesian Analysis (http://bayesian.org/

Slum health: diseases of neglected populations.

BackgroundUrban slums, like refugee communities, comprise a social cluster that engenders a distinct set of health problems. With 1 billion people currently estimated to live in such communities, this neglected population has become a major reservoir for a wide spectrum of health conditions that the formal health sector must deal with.DiscussionUnlike what occurs with refugee populations, the formal health sector becomes aware of the health problems of slum populations relatively late in the course of their illnesses. As such, the formal health sector inevitably deals with the severe and end-stage complications of these diseases at a substantially greater cost than what it costs to manage non-slum community populations. Because of the informal nature of slum settlements, and cultural, social, and behavioral factors unique to the slum populations, little is known about the spectrum, burden, and determinants of illnesses in these communities that give rise to these complications, especially of those diseases that are chronic but preventable. In this article, we discuss observations made in one slum community of 58,000 people in Salvador, the third largest city in Brazil, to highlight the existence of a spectrum and burden of chronic illnesses not likely to be detected by the formal sector health services until they result in complications or death. Lack of health-related data from slums could lead to inappropriate and unrealistic allocation of health care resources by the public and private providers. Similar misassumptions and misallocations are likely to exist in other nations with large urban slum populations.SummaryContinued neglect of ever-expanding urban slum populations in the world could inevitably lead to greater expenditure and diversion of health care resources to the management of end-stage complications of diseases that are preventable. A new approach to health assessment and characterization of social-cluster determinants of health in urban slums is urgently needed

On adaptive versus nonadaptive bounded query machines

AbstractThe polynomial-time adaptive (Turing) and nonadaptive (truth-table) bounded query machines are compared with respect to sparse oracles. A k-query adaptive machine has been found which, relative to a sparse oracle, cannot be simulated by any (2k−2)-query nonadaptive machine, even with a different sparse oracle. Conversely, there is a (3·2k−2)-query nonadaptive machine which, relative to a sparse oracle, cannot be simulated by any k-query adaptive machine, with any sparse oracle

A polynomial-time computable curve whose interior has a nonrecursive measure

AbstractA polynomial-time computable simple curve is constructed such that its measure in the two-dimensional plane is positive. This construction is applied to prove the following two results: 1.1) there exists a polynomial-time computable simple closed curve in the two-dimensional plane such that the measure of its interior region is a nonrecursive real number;2.(2) there exists a polynomial-time computable simple curve in the two-dimensional plane such that its length is finite but is a nonrecursive real number

Computational Fluid Dynamics Simulations of an In-line Slot and Tooth Rotor-Stator Mixer

Unlike conventional stirred tanks, rotor-stator mixers provide high deformation rates to a relatively limited volume, resulting in a region in which intensive mixing, milling, and/or dispersion operations can occur. FLUENT was used to conduct three-dimensional CFD simulations of the IKA prototype mixer, an in-line slot and tooth rotor-stator device, for a low-speed low-flow condition and a high-speed high-flow condition. The main objective of this project was to develop a CFD model of the IKA prototype mixer with the necessary refinement in the shear gap to accurately resolve these high shear values. A grid independence study was conducted to quantify the influence of shear gap grid resolution on the computed flow solution and determine the grid level most suitable for further detailed investigation. Convergence in highly-directed regions was shown to be faster than in more-open regions. Velocity and total deformation fields in the stator slots and the shear gap were examined for both operating scenarios. Differences in the fluid behaviour between the two scenarios are discussed

Self-similar solutions for the interaction of relativistic ejecta with an ambient medium

We find self-similar solutions to describe the interaction of spherically symmetric ejecta expanding at relativistic speeds with an ambient medium having a power law density distribution. Using this solution, the time evolution of the Lorentz factor of the outer shock is derived as a function of the explosion energy, the mass of the ejecta, and parameters for the ambient medium. These solutions are an ultra-relativistic version of the solutions for the circumstellar interaction of supernova ejecta obtained by Chevalier and extensions of the relativistic blast wave solutions of Blandford & Mckee.Comment: 12 pages, 1 figure, accepted for publication in Ap

The Dual Roles of NF-kB Activation in Prx1+ Mesenchymal Cells in Health and Disease

Nuclear factor kappa-B (NF-kB) was discovered in 1986 and has since been studied extensively for its role as a master inflammatory transcription factor. As inflammation is critical for normal immune response but its chronic presence can be detrimental under pathological conditions, I sought to investigate the role of NF-kB in mesenchymal tissues under diabetic and homeostatic conditions. Aberrant activation of NF-kB and chronic inflammation have been documented in diabetic complications of kidney, eyes and cardiovascular system. Here I found that experimental type 1 diabetes caused hyperactivation of NF-kB in skeletal stem cells (SSCs) in the long bones of mice. Deletion of Ikkb, an activator of canonical NF-kB pathway, in Prx1+ (Paired Related Homeobox 1) SSCs prevented NF-kB activity and reversed the effect of diabetes on SSC apoptosis and anti-proliferation. In addition, it rescued the immuno-regulatory property of SSCs by transforming growth factor beta-1 (TGFb1), which in turn promoted macrophage polarization towards pro-resolving phenotype. These findings point to a detrimental role of NF-kB under pathologic condition such as type 1 diabetes. Surprisingly, I observed that NF-kB inactivation in Prx1+ cells caused hyper-inflammation and skin lesion that progressed with aging. The location of lesion was specific to ventral skin, consistent with the pattern of Prx1+ expression in mesenchyme derived from embryonic lateral plate mesoderm. Ikkb deletion in Col1a2Cre+ skin fibroblasts, but not Adipoq-Cre+ mature adipocytes, was sufficient to cause local inflammation but not in spleen or bone marrow. Single cell RNA sequencing analysis revealed an immune response that was characterized by an exaggerated inflammatory macrophage and type 2 T cell responses in the experimental animals. Furthermore, Prx1+ fibroblasts that had Ikkb deletion overexpressed CCL11 (also known as eotaxin-1), a potent chemoattractant for eosinophils. These results indicate Ikkb-NFkB activity in fibroblasts as an important contributor of immune homeostasis against an inflammatory response that mirrors the signs of atopic dermatitis. Thus, Ikkb-NFkB exhibits dual and opposing roles in Prx1+ mesenchymal cells where it is critical for homeostasis in dermal immunity, but it is detrimental in diabetic bone healing. These differential responses may be explained by the healthy or diseased status and/or by the niche-specific role of Prx1+ cells

Higher Dimensional Operators in the MSSM

The origin and the implications of higher dimensional effective operators in 4-dimensional theories are discussed in non-supersymmetric and supersymmetric cases. Particular attention is paid to the role of general, derivative-dependent field redefinitions which one can employ to obtain a simpler form of the effective Lagrangian. An application is provided for the Minimal Supersymmetric Standard Model extended with dimension-five R-parity conserving operators, to identify the minimal irreducible set of such operators after supersymmetry breaking. Among the physical consequences of this set of operators are the presence of corrections to the MSSM Higgs sector and the generation of "wrong"-Higgs Yukawa couplings and fermion-fermion-scalar-scalar interactions. These couplings have implications for supersymmetry searches at the LHC.Comment: Contribution to the proceedings of the "Susy 2008" conference; (6 pages