323,161 research outputs found
SPATIAL CHOW-LIN METHODS: BAYESIAN AND ML FORECAST COMPARISONS
Get PDFCompleting data that are collected in disaggregated and heterogeneous spatial units is a quite frequent problem in spatial analyses of regional data. Chow and Lin (1971) (CL) were the rst to develop a uni ed framework for the three problems (interpolation, extrapolation and distribution) of predicting disaggregated times series by so-called indicator series. This paper develops a spatial CL procedure for disaggregating cross-sectional spatial data and compares the Maximum Likelihood and Bayesian spatial CL forecasts with the naive pro rata error distribution. We outline the error covariance structure in a spatial context, derive the BLUE for the ML estimator and the Bayesian estimation procedure by MCMC. Finally we
apply the procedure to European regional GDP data and discuss the disaggregation assumptions. For the evaluation of the spatial Chow-Lin procedure we assume that only NUTS 1 GDP is known and predict it at NUTS 2 by using employment and spatial information available at NUTS 2. The spatial neighborhood is de ned by the inverse travel time by car in minutes. Finally, we present the forecast accuracy criteria comparing the predicted values with the actual observations.
Chow Theorem and structure of Carnot-Caratheodory balls
Get PDFopenThis thesis is meant to be a study on the role of the C-C metrics in the Chow theorem and on the structure of C-C balls.
It opens with a section in which we give the definitions of vector field and bracket and we state the properties of the latter.
Then we give the definition of the most important object of this work: the Carnot-Caratheodory metrics and we state some basic propositions on its behavior, hinting also to some metrics which are equivalent to it.
We now proceed giving preliminary notions about exponential maps on a compact set of R^n, we state the Campbell-Hausdorff formula for two smooth vector fields and we introduce an object defined as a composition of exponentials E(J,t).
We finally state the Chow theorem for m smooth vector fields in R^n satisfying the Chow-Hoermander condition. We prove it using the Campbell-Hausdorff formula and defining through E(J,t) n approximated exponential maps whose composition provides us with a local diffeomorphism.
This theorem is particularly important because it tells us that under Chow-Hoermander condition we can regain directions that would be otherwise prohibited.
We introduce the doubling metric spaces and in particular we state a theorem on the structure of C-C balls: the Nagel-Stein-Wainger theorem, which provides us with the size of the C-C balls and tells us they are represented as the image of rectangles under the exponential map.
At last, we close this work with a variant of the structure theorem.This thesis is meant to be a study on the role of the C-C metrics in the Chow theorem and on the structure of C-C balls.
It opens with a section in which we give the definitions of vector field and bracket and we state the properties of the latter.
Then we give the definition of the most important object of this work: the Carnot-Caratheodory metrics and we state some basic propositions on its behavior, hinting also to some metrics which are equivalent to it.
We now proceed giving preliminary notions about exponential maps on a compact set of R^n, we state the Campbell-Hausdorff formula for two smooth vector fields and we introduce an object defined as a composition of exponentials E(J,t).
We finally state the Chow theorem for m smooth vector fields in R^n satisfying the Chow-Hoermander condition. We prove it using the Campbell-Hausdorff formula and defining through E(J,t) n approximated exponential maps whose composition provides us with a local diffeomorphism.
This theorem is particularly important because it tells us that under Chow-Hoermander condition we can regain directions that would be otherwise prohibited.
We introduce the doubling metric spaces and in particular we state a theorem on the structure of C-C balls: the Nagel-Stein-Wainger theorem, which provides us with the size of the C-C balls and tells us they are represented as the image of rectangles under the exponential map.
At last, we close this work with a variant of the structure theorem
Chow-Lam recovery
Get PDFWe study the conditions under which a subvariety of the Grassmannian may be recovered from certain of its linear projections. In the special case that our Grassmannian is projective space, this is equivalent to asking when a variety can be recovered from its Chow form; the answer is "always" by work of Chow in 1937. In the general Grassmannian setting, the analogous question is when a variety can be recovered from its Chow-Lam form. We give both necessary conditions for recovery and families of examples where, in contrast with the projective case, recovery is not possible
Análise do acoplamento pressão-velocidade nas equações de Navier-Stokes utilizando o método dos volumes finitos baseado em elementos e solução acoplada
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Engenharia Mecânica.Este trabalho tem como objetivo estudar os métodos FIELDS e Rhie-Chow para tratamento do acoplamento pressão-velocidade na solução das equações de Navier-Stokes e realizar sua implementação computacional. Estes métodos apresentam diferentes maneiras de introduzir a pressão na equação de conservação da massa para a solução acoplada da pressão e velocidade. Ambos se utilizam de técnicas baseadas em funções de interpolação, que são decorrentes das próprias equações de conservação da quantidade de movimento, de forma a estabelecer um forte acoplamento entre as variáveis das equações. A aplicação em malhas não-estruturadas é realizada através do método dos volumes finitos baseado em elementos. Com o simulador desenvolvido, os métodos FIELDS e Rhie-Chow são avaliados através da solução de problemas conhecidos na literatura. Primeiro, são realizadas avaliações individuais dos métodos quanto à sua estabilidade e consistência. Em seguida são traçados comparativos entre as soluções obtidas. São analisadas características como: qualidade das soluções, convergência, influência do passo de tempo, tempos de solução dos sistemas lineares e montagem da matriz de coeficientes. The main goal of this work is the study of the FIELDS and Rhie-Chow methods for treatment of the pressure-velocity coupling in the solution of the Navier-Stokes equations and develop their computational codes. These methods have different ways of introducing the pressure in the mass conservation equation when a coupled solution is sought. Both use techniques based on interpolation functions, which come from the momentum conservation equations, in a way that a strong coupling between the equations is established. The use on unstructured meshes is performed by the element based finite volume method. The FIELDS and Rhie-Chow methods are evaluated by solving well-known testing problems from the literature. First, they are individually evaluated based on their stability and robustness. Then, the solutions are compared and analyzed according to the following criteria: solution quality, convergence, time step influence, CPU time spent to solve linear systems and assembling the global coefficient matrix
Chow Time Restaurant in Gadsden, Ala.
No full textInterior view of the Chow Time Restaurant in Gadsden, Ala
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Chow rings of matroids are Koszul
Get PDFChow rings of matroids were instrumental in the resolution of the
Heron-Rota-Welsh Conjecture by Adiprasito, Huh, and Katz and in the resolution
of the Top-Heavy Conjecture by Braden, Huh, Matherne, Proudfoot, and Wang. The
Chow ring of a matroid is a commutative, graded, Artinian, Gorenstein algebra
with linear and quadratic relations defined by the matroid. Dotsenko
conjectured that the Chow ring of any matroid is Koszul. The purpose of this
paper is to prove Dotsenko's conjecture. We also show that the augmented Chow
ring of a matroid is Koszul. As a corollary, we show that the Chow rings and
augmented Chow rings of matroids have rational Poincar\'{e} series.Comment: To appear in Mathematische Annalen. This preprint has not undergone
peer review or any post-submission improvements or corrections. The Version
of Record of this article is published in Mathematische Annalen, and is
available online at https://doi.org/10.1007/s00208-022-02506-
PIOMETRA EM CANINO DA RAÇA CHOW-CHOW
No full textA piometra, também conhecida como hiperplasia endometrial cística, é caracterizada pela presença de coleção purulenta no corpo do útero com invasão microbiana originalmente da flora vaginal, sendo Escherichia coli a bactéria mais comumente isolada em fêmeas felinas e caninas. Muitos fatores predisponentes estão envolvidos, um deles é a idade, quanto mais idoso o animal, mais suscetível. Outro fator desencadeante é o uso de hormônios contraceptivos. O animal pode apresentar quadro de poliúria-polidipsia, desidratação, corrimento vulvar e hipotermia. No hemograma, é comum de encontrarem-se formas normocíticas de anemia e neutrofilia com desvio à esquerda. O objetivo deste trabalho foi relatar um caso atendido no Hospital Veterinário da Unoesc de Xanxerê. Um canino, fêmea, raça Chow-Chow, de seis anos, pesando 15 kg, com o histórico de corrimento vulvar há uma semana, inapetência e polidipsia. Ao exame físico, o animal apresentou abdômen abaulado, desidratação e corrimento purulento vulvar. Ao hemograma, observou-se anemia normocítica e hipocrômica, além de leucocitose por neutrofilia com desvio à esquerda. Com base nos sinais clínicos e exames, a suspeita foi de piometra; então, mediante anestesia geral, foi realizada a castração (ovariosalpingohisterectomia). Na cultura microbiológica e antibiograma foi constatada a presença de Escherichia coli. No pós-operatório, a paciente foi medicada com ceftriaxona 20 mg/kg IV, tramadol 3 mg/kg IV, hemolitan pet 0,1 ml/kg VO e metronidazol 250g VO. Foi mantida em observação de 17 março de 2014 até 25 de março de 2014 no Hospital Veterinário da Unoesc de Xanxerê. O tratamento foi efetivo, pois se observou melhora no quadro clínico e na condição corporal.Palavras-chave: Infecção uterina. Cadela. Hiperplasia endometrial cística. Hormônios contraceptivos
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Performance and Professional Wrestling
No full textPerformance and Professional Wrestling is the first edited volume to consider professional wrestling explicitly from the vantage point of theatre and performance studies. Moving beyond simply noting its performative qualities or reading it via other performance genres, this collection of essays offers a complete critical reassessment of the popular sport.
Topics such as the suspension of disbelief, simulation, silence and speech, physical culture, and the performance of pain within the squared circle are explored in relation to professional wrestling, with work by both scholars and practitioners grouped into seven short sections:
Audience
Circulation
Lucha
Gender
Queerness
Bodies
Race
A significant re-reading of wrestling as a performing art, Performance and Professional Wrestling makes essential reading for scholars and students intrigued by this uniquely theatrical sport
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