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Title: Influence of Injector Location on Part-Load Performance Characteristics of Natural Gas Direct-Injection in a Spark Ignition Engine
Creator: Hall, Carrie, Sevik, James, Pamminger, Michael, Wallner, Thomas, Scarcelli, Riccardo, Boyer, Brad, Wooldridge, Steven, Miers, Scott
Date: 2016
Publisher: SAE International

Title: Using Peer Navigators to Address the Integrated Healthcare Needs of African Americans with Serious Mental Illness
Creator: Corrigan, Patrick
Date: 2017, 2017
Publisher: American Psychiatric Association
Description: Objective...
Show moreObjective Impact of a peer navigator program (PNP) develop by a community based participatory research team was examined on African Americans with serious mental illness who were homeless. Methods Research participants were randomized to PNP or a treatment-as-usual control group for one year. Data on physical and mental health, recovery, and quality of life were collected at baseline, 4, 8 and 12 months. Results Findings from group by trial ANOVAs of omnibus measures of the four constructs showed significant impact over the one year for participants in PNP compared to control described by small to moderate effect sizes. These differences emerged even though both groups showed significant improvements in reduced homelessness and insurance coverage. Conclusions Implications for improving in-the-field health care for this population are discussed. Whether these results occurred because navigators were peers per se needs to be examined in future research.
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Title: Three agendas for changing the public stigma of mental illness.
Creator: Corrigan, Patrick
Date: 2018, 2017
Publisher: American Psychological Association
Description: OBJECTIVE:...
Show moreOBJECTIVE: Antistigma programs may be guided by 3 differing agendas: services (promote treatment engagement), rights (help people achieve rightful goals), and self-worth (facilitate self-worth and efficacy). This study examined the construct validity of this perspective by examining the factor structure of importance ratings of the 3 agendas. The study examined how importance might be viewed differently by the population as a whole versus a subsample of people who reported previous experience with mental health services and hence could be directly harmed by stigma. METHODS: 373 individuals recruited using Mechanical Turk completed importance ratings for each of the 3 agendas. Measures of public stigma were completed to examine concurrent validity of importance ratings. Those who reported taking medications for a psychiatric disorder were divided into a separate group and completed a measure of self-stigma. RESULTS: Outcomes seemed to confirm the factor structure of the 3 agendas model thereby offering partial support for the framework. Group analyses showed the services agenda was viewed as more important than rights or self-worth. People with mental health experience viewed the services agenda as more important than the other 2. However, dividing the mental health group into low and high self-stigma revealed that those with low self-stigma rated the rights agenda as more important. Conclusions and Implication for Practice: Participants with lower self-stigma identify the harm brought by stigma and thus endorse rights and self-worth more than those with higher self-stigma. Implications of these findings are discussed to assist to prioritize agendas for public health campaigns.
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Title: They Aren't Like Me, They are Bad, and They are to Blame: A Theoretically-Informed Study of Stigma of Hoarding Disorder and Obsessive-Compulsive Disorder
Creator: Chasson, Gregory S., Guy, Arryn A., Bates, Sage, Corrigan, Patrick W.
Date: 2018, 2018
Publisher: Elsevier

Title: Transdiagnostic Emotional Vulnerabilities Linking Obsessive-Compulsive and Depressive Symptoms in a Community-Based Sample of Adolescents
Creator: Chasson, Gregory S., Bello, Mariel S., Luxon, Alexandria M., Graham, Trevor A. A., Leventhal, Adam M.
Date: 2017, 2017
Publisher: Wiley Periodicals, Inc.
Description: Background: Transdiagnostic emotional vulnerabilities are suspected to underlie psychopathologic comorbidity but have received little...
Show moreBackground: Transdiagnostic emotional vulnerabilities are suspected to underlie psychopathologic comorbidity but have received little attention in adolescent emotional pathology literature. We examined distress tolerance, anxiety sensitivity, and anhedonia as concomitant transdiagnostic mechanisms that account for (i.e., statistically mediate) the covariance between adolescent obsessive-compulsive disorder (OCD) and major depressive disorder (MDD) symptoms. Method: Data on MDD, OCD, and the three aforementioned transdiagnostic vulnerabilities were collected from a community-based sample of 3,094 9th graders in a large metropolitan area and analyzed using mixed effects modeling to evaluate mediation effects. Results: Individually and when controlling for each other, all three transdiagnostic vulnerabilities mediated the relation between OCD and MDD symptoms both before and after adjusting for demographics. Conclusions: Distress tolerance, anxiety sensitivity, and anhedonia may be unique mechanisms accounting for comorbidity between OCD and MDD symptoms in youth. Longitudinal evaluation of these candidate transdiagnostic emotional vulnerabilities in adolescent OCD-MDD comorbidity is warranted.
Sponsorship: Grant sponsor: National Institute on Drug Abuse; Contract grant number: R01?DA033296.
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Title: Examining Partnership-Health Associations Among Lesbian Women and Gay Men Using Population-Level Data
Creator: Du Bois, Steve N., Legate, Nicole, Kendall, Ashley D.
Date: 2019
Description: Abstract...
Show moreAbstract Purpose: The aim was to provide the first broad assessment of partnership-health associations across partnership statuses among sexual minority individuals. Methods: Using population-level data from the 2016 U.S. Behavioral Risk Factor Surveillance System, specifically the 26 states/territories that assessed sexual orientation and gender identity, we ran analyses of covariance and logistic regressions to compare lesbian and gay individuals (N = 2963) of different partnership statuses in general health, physical health and health conditions, mental health, health behaviors, and healthcare access/utilization domains. Results: All omnibus and logistic regression models were significant (p < 0.001). Follow-up pairwise comparisons of mean differences across partnership groups revealed that in at least one variable in the general health, mental health, health behaviors, and healthcare access/utilization domains, married lesbian and gay individuals reported the best health, followed by partnered, single, and then divorced, separated, and widowed lesbian and gay individuals (p < 0.001). Exceptions included variables in the physical health and health conditions domain, the health behaviors of smoking and heavy drinking, and ever having an HIV test. When stratifying by sex, for both gay men and lesbian women being married or partnered related to the best health in at least one variable in each health domain, and in the majority of all outcome variables. Conclusion: This article provides the first evidence for partnership-health associations among gay and lesbian individuals based on a large-scale, multi-domain test of population-level data. Future research could examine temporal links between same-sex marriage legislation and health outcomes among sexual minority individuals.
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Title: Binary hidden Markov models and varieties, AS2012 Special Volume, part 2: This issue includes a second series of papers from talks, posters and collaborations resulting from and inspired by the Algebraic Statistics in the Alleghenies Conference at Penn State, which took place in July 2012.
Creator: Critch, Andrew
Date: 2013, 2013
Description: This paper closely examines HMMs in which all the hidden random variables are...
Show moreThis paper closely examines HMMs in which all the hidden random variables are binary. Its main contributions are (1) a birational parametrization for every such HMM, with an explicit inverse for recovering the hidden parameters in terms of observables, (2) a semialgebraic model membership test for every such HMM, and (3) minimal dening equations for the 4-node fully binary model, comprising 21 quadrics and 29 cubics, which were computed using Grobner bases in the cumulant coordinates of Sturmfels and Zwiernik. The new model parameters in (1) are rationally identiable in the sense of Sullivant, Garcia-Puente, and Spielvogel, and each model's Zariski closure is therefore a rational projective variety of dimension 5. Grobner basis computations for the model and its graph are found to be considerably faster using these parameters. In the case of two hidden states, item (2) supersedes a previous algorithm of Schonhuth which is only generically dened, and the dening equations (3) yield new invariants for HMMs of all lengths 4. Such invariants have been used successfully in model selection problems in phylogenetics, and one can hope for similar applications in the case of HMMs.
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Collection: Journal of Algebraic Statistics

Title: On Polyhedral Approximations of Polytopes for Learning Bayesian Networks, AS2012 Special Volume, part 2: This issue includes a second series of papers from talks, posters and collaborations resulting from and inspired by the Algebraic Statistics in the Alleghenies Conference at Penn State, which took place in July 2012.
Creator: Studeny, Milan, Haws, David C.
Date: 2013, 2013
Description: The motivation for this paper is the geometric approach to statistical learning Bayesiannetwork (BN) structures. We review three vector...
Show moreThe motivation for this paper is the geometric approach to statistical learning Bayesiannetwork (BN) structures. We review three vector encodings of BN structures. The first one has been used by Jaakkola et al. [9] and also by Cussens [4], the other two use special integral vectors formerly introduced, called imsets [18, 20]. The topic is the comparison of outer polyhedral approximations of the corresponding polytopes. We show how to transform the inequalities suggested by Jaakkola et al. [9] into the framework of imsets. The result of our comparison is the observation that the implicit polyhedral approximation of the standard imset polytope suggested in [21] gives a tighter approximation than the (transformed) explicit polyhedral approximation from [9]. As a consequence, we confirm a conjecture from [21] that the above-mentioned implicit polyhedral approximation of the standard imset polytope is an LP relaxation of that polytope. In the end, we review recent attempts to apply the methods of integer programming to learning BN structures and discuss the task of finding suitable explicit LP relaxation in the imset-based approach.
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Collection: Journal of Algebraic Statistics

Title: Learning Coefficient in Bayesian Estimation of Restricted Boltzmann Machine, AS2012 Special Volume, part 2: This issue includes a second series of papers from talks, posters and collaborations resulting from and inspired by the Algebraic Statistics in the Alleghenies Conference at Penn State, which took place in July 2012.
Creator: Aoyagi, Miki
Date: 2013, 2013
Description: We consider the real log canonical threshold for the learning model in Bayesian estimation. This threshold corresponds to a learning...
Show moreWe consider the real log canonical threshold for the learning model in Bayesian estimation. This threshold corresponds to a learning coefficient of generalization error in Bayesian estimation, which serves to measure learning efficiency in hierarchical learning models [30, 31, 33]. In this paper, we clarify the ideal which gives the log canonical threshold of the restricted Boltzmann machine and consider the learning coefficients of this model.
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Collection: Journal of Algebraic Statistics

Title: Phylogenetic invariants for group-based models, AS2012 Special Volume, part 1: This issue includes a second series of papers from talks, posters and collaborations resulting from and inspired by the Algebraic Statistics in the Alleghenies Conference at Penn State, which took place in July 2012.
Creator: Donten-Bury, Maria, Michalek, Mateusz
Date: 2012, 2012
Description: In this paper we investigate properties of algebraic varieties representing group-based phylogenetic models. We propose a method of generating...
Show moreIn this paper we investigate properties of algebraic varieties representing group-based phylogenetic models. We propose a method of generating many phylogenetic invariants. We prove that we obtain all invariants for any tree for the two-state Jukes-Cantor model. We conjecture that for a large class of models our method can give all phylogenetic invariants for any tree. We show that for 3-Kimura our conjecture is equivalent to the conjecture of Sturmfels and Sullivant [22, Conjecture 2]. This, combined with the results in [22], would make it possible to determine all phylogenetic invariants for any tree for 3-Kimura model, and also other phylogenetic models. Next we give the (first) examples of non-normal varieties associated to general group-based model for an abelian group. Following Kubjas [17] we prove that for many group-based models varieties associated to trees with the same number of leaves do not have to be deformation equivalent.
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Collection: Journal of Algebraic Statistics

Title: Properties of semi-elementary imsets as sums of elementary imsets
Creator: Kashimura, Takuya, Sei, Tomonari, Takemura, Akimichi, Tanaka, Kentaro
Date: 2011, 2011
Description: We study properties of semi-elementary imsets and elementary imsets introduced by Studeny [10]. The rules of the semi-graphoid axiom ...
Show moreWe study properties of semi-elementary imsets and elementary imsets introduced by Studeny [10]. The rules of the semi-graphoid axiom (decomposition, weak union and contraction) for conditional independence statements can be translated into a simple identity among three semi-elementary imsets. By recursively applying the identity, any semi-elementary imset can be written as a sum of elementary imsets, which we call a representation of the semi-elementary imset. A semi-elementary imset has many representations. We study properties of the set of possible representations of a semi-elementary imset and prove that all representations are connected by relations among four elementary imsets.
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Collection: Journal of Algebraic Statistics

Title: Higher Connectivity of Fiber Graphs of Gröbner Bases, AS2012 Special Volume, part 2: This issue includes a second series of papers from talks, posters and collaborations resulting from and inspired by the Algebraic Statistics in the Alleghenies Conference at Penn State, which took place in July 2012.
Creator: Potka, Samu
Date: 2013, 2013
Description: Fiber graphs of Gröbner bases from contingency tables are important in statistical hypothesis testing, where one studies random walks on these...
Show moreFiber graphs of Gröbner bases from contingency tables are important in statistical hypothesis testing, where one studies random walks on these graphs using the Metropolis-Hastings algorithm. The connectivity of the graphs has implications on how fast the algorithm converges. In this paper, we study a class of ber graphs with elementary combinatorial techniques and provide results that support a recent conjecture of Engström: the connectivity is given by the minimum vertex degree.
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Collection: Journal of Algebraic Statistics

Title: An Iterative Method Converging to a Positive Solution of Certain Systems of Polynomial Equations
Creator: Cartwright, Dustin
Date: 2011, 2011
Description: We present a numerical algorithm for finding real non-negative solutions to a certain class of polynomial equations. Our methods are based on...
Show moreWe present a numerical algorithm for finding real non-negative solutions to a certain class of polynomial equations. Our methods are based on the expectation maximization and iterative proportional fitting algorithms, which are used in statistics to find maximum likelihood parameters for certain classes of statistical models. Since our algorithm works by iteratively improving an approximate solution, we find approximate solutions in the cases when there are no exact solutions, such as overconstrained systems.
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Collection: Journal of Algebraic Statistics

Title: Geometry of Higher-Order Markov Chains, AS2012 Special Volume, part 1: This issue includes a second series of papers from talks, posters and collaborations resulting from and inspired by the Algebraic Statistics in the Alleghenies Conference at Penn State, which took place in July 2012.
Creator: Sturmfels, Bernd
Date: 2012, 2012
Description: We determine an explicit Gr ?obner basis, consisting of linear forms and determinantal quadrics, for the prime ideal of Raftery’s mixture...
Show moreWe determine an explicit Gr ?obner basis, consisting of linear forms and determinantal quadrics, for the prime ideal of Raftery’s mixture transition distribution model for Markov chains. When the states are binary, the corresponding projective variety is a linear space, the model itself consists of two simplices in a cross-polytope, and the likelihood function typically has two local maxima. In the general non-binary case, the model corresponds to a cone over a Segre variety.
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Collection: Journal of Algebraic Statistics

Title: Betti Numbers of Cut Ideals of Trees, AS2012 Special Volume, part 2: This issue includes a second series of papers from talks, posters and collaborations resulting from and inspired by the Algebraic Statistics in the Alleghenies Conference at Penn State, which took place in July 2012.
Creator: Potka, Samu, Sarmiento, Camilo
Date: 2013, 2013
Description: Cut ideals, introduced by Sturmfels and Sullivant, are used in phylogenetics and algebraic statistics. We study the minimal free resolutions...
Show moreCut ideals, introduced by Sturmfels and Sullivant, are used in phylogenetics and algebraic statistics. We study the minimal free resolutions of cut ideals of tree graphs. By employing basic methods from topological combinatorics, we obtain upper bounds for the Betti numbers of this type of ideals. These take the form of simple formulas on the number of vertices, which arise from the enumeration of induced subgraphs of certain incomparability graphs associated to the edge sets of trees.
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Collection: Journal of Algebraic Statistics

Title: The geometry of Sloppiness
Creator: Dufresne, Emilie, Harrington , Heather A, Raman, Dhruva V
Date: 2018, 2018-09-24
Description: The use of mathematical models in the sciences often requires the estimation of unknown parameter values from data. Sloppiness provides...
Show moreThe use of mathematical models in the sciences often requires the estimation of unknown parameter values from data. Sloppiness provides information about the uncertainty of this task. In this paper, we develop a precise mathematical foundation for sloppiness and define rigorously its key concepts, such as `model manifold', in relation to concepts of structural identifiability. We redefine sloppiness conceptually as a comparison between the premetric on parameter space induced by measurement noise and a reference metric. This opens up the possibility of alternative quantification of sloppiness, beyond the standard use of the Fisher Information Matrix, which assumes that parameter space is equipped with the usual Euclidean and the measurement error is infinitesimal. Applications include parametric statistical models, explicit time dependent models, and ordinary differential equation models.
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Collection: Journal of Algebraic Statistics

Title: Mixture models for rating data: the method of moments via Groebner bases
Creator: Iannario, Maria, Simone, Rosaria
Date: 2017, 2017-12-26
Description: A recent thread of research in ordinal data analysis involves a class of mixture models that designs the responses as the combination of the...
Show moreA recent thread of research in ordinal data analysis involves a class of mixture models that designs the responses as the combination of the two main aspects driving the decision pro- cess: a feeling and an uncertainty components. This novel paradigm has been proven flexible to account also for overdispersion. In this context, Groebner bases are exploited to estimate model parameters by implementing the method of moments. In order to strengthen the validity of the moment procedure so derived, alternatives parameter estimates are tested by means of a simulation experiment. Results show that the moment estimators are satisfactory per se, and that they significantly reduce the bias and perform more efficiently than others when they are set as starting values for the Expectation-Maximization algorithm.
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Collection: Journal of Algebraic Statistics

Title: Ideal-Theoretic Strategies for Asymptotic Approximation of Marginal Likelihood Integrals
Creator: Lin, Shaowei
Date: 2017, 2017-02-08
Description: The accurate asymptotic evaluation of marginal likelihood integrals is a fundamental problem in Bayesian statistics. Following the approach...
Show moreThe accurate asymptotic evaluation of marginal likelihood integrals is a fundamental problem in Bayesian statistics. Following the approach introduced by Watanabe, we translate this into a problem of computational algebraic geometry, namely, to determine the real log canonical threshold of a polynomial ideal, and we present effective methods for solving this problem. Our results are based on resolution of singularities. They apply to parametric models where the Kullback-Leibler distance is upper and lower bounded by scalar multiples of some sum of squared real analytic functions. Such models include finite state discrete models.
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Collection: Journal of Algebraic Statistics

Title: Unimodular hierarchical models and their Graver bases
Creator: Bernstein, Daniel Irving, O'Neill, Christopher
Date: 2017, 2017-12-26
Description: Given a simplicial complex whose vertices are labeled with positive integers, one can associate a vector configuration whose corresponding...
Show moreGiven a simplicial complex whose vertices are labeled with positive integers, one can associate a vector configuration whose corresponding toric variety is the Zariski closure of a hierarchical model. We classify all the vertex-weighted simplicial complexes that give rise to unimodular vector configurations. We also provide a combinatorial characterization of their Graver bases.
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Collection: Journal of Algebraic Statistics

Title: Mixtures and products in two graphical models
Creator: Seigal,Anna, Montufar, Guido
Date: 2018, 2018-09-24
Description: We compare two statistical models of three binary random variables. One is a mixture model and the other is a product of mixtures model called...
Show moreWe compare two statistical models of three binary random variables. One is a mixture model and the other is a product of mixtures model called a restricted Boltzmann machine. Although the two models we study look different from their parametrizations, we show that they represent the same set of distributions on the interior of the probability simplex, and are equal up to closure. We give a semi-algebraic description of the model in terms of six binomial inequalities and obtain closed form expressions for the maximum likelihood estimates. We briefly discuss extensions to larger models.
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Collection: Journal of Algebraic Statistics

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