• Title/Summary/Keyword: matched pairs models

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Visualizations for Matched Pairs Models Using Modified Correspondence Analysis

  • Lee, Chanyoon;Choi, Yong-Seok
    • Communications for Statistical Applications and Methods
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    • v.21 no.4
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    • pp.275-284
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    • 2014
  • Matched pairs are twice continuously measured data with the same categories. They can be represented as the square contingency tables. We can also consider symmetry and marginal homogeneity. Moreover, we can infer the matched pairs models; the symmetry model, the quasi-symmetry model, and the ordinal quasi-symmetry model. These inferences are involved in assumptions for special distributions. In this study, we visualize matched pairs models using modified correspondence analysis. Modified correspondence analysis can be used when square contingency tables are given; consequently, it is involved in the square and asymmetric correspondence matrix. This technique does not need assumptions for special distributions and is more helpful than the correspondence analysis to visualize matched pairs models.

Mixed Linear Models with Censored Data

  • Ha, Il-do;Lee, Youngjo-;Song, Jae-Kee
    • Journal of the Korean Statistical Society
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    • v.28 no.2
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    • pp.211-223
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    • 1999
  • We propose a simple estimation procedure in the mixed linear models with censored normal data, using both Buckly and James(1979) type pseudo random variables and Lee and Nelder's(1996) estimation procedure. The proposed method is illustrated with the matched pairs data in Pettitt(1986).

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Automatic partial shape recognition system using adaptive resonance theory (적응공명이론에 의한 자동 부분형상 인식시스템)

  • 박영태;양진성
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.3
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    • pp.79-87
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    • 1996
  • A new method for recognizing and locating partially occluded or overlapped two-dimensional objects regardless of their size, translation, and rotation, is presented. Dominant points approximating occuluding contoures of objects are generated by finding local maxima of smoothed k-cosine function, and then used to guide the contour segment matching procedure. Primitives between the dominant points are produced by projecting the local contours onto the line between the dominant points. Robust classification of primitives. Which is crucial for reliable partial shape matching, is performed using adaptive resonance theory (ART2). The matched primitives having similar scale factors and rotation angles are detected in the hough space to identify the presence of the given model in the object scene. Finally the translation vector is estimated by minimizing the mean squred error of the matched contur segment pairs. This model-based matching algorithm may be used in diveerse factory automation applications since models can be added or changed simply by training ART2 adaptively without modifying the matching algorithm.

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Hypertension and the Risk of Breast Cancer in Chilean Women: a Case-control Study

  • Pereira, Ana;Garmendia, Maria Luisa;Alvarado, Maria Elena;Albala, Cecilia
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.11
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    • pp.5829-5834
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    • 2012
  • Background: Breast cancer is the most common cancer in women worldwide. Although different metabolic factors have been implicated in breast cancer development, the relationship between hypertension and breast cancer has not been elucidated. Aim: To evaluate hypertension as a risk factor for breast cancer in Chilean women of low and middle socio-economic status. Methods: We conducted an age-matched (1:1) case-control study in 3 hospitals in Santiago, Chile. Breast cancer cases (n=170) were histopathologically confirmed. Controls had been classified as Breast Imaging Reporting and Data System I (negative) or II (benign findings) within 6 months of recruitment. Blood pressure was measured using a mercury sphygmomanometer and standardized procedures. We used 2 hypertension cut-off points: blood pressures of ${\geq}140/90$ mmHg and ${\geq}130/85$ mmHg. Fasting insulin and glucose levels were assessed, and anthropometric, sociodemographic, and behavioral information were collected. Odds ratios and 95% confidence intervals were estimated for the entire sample and restricted to postmenopausal women using multivariable conditional logistic regression models. Results: Hypertension (${\geq}140/90$ mmHg) was significantly higher in cases (37.1%) than controls (17.1%) for the entire sample and in postmenopausal pairs (44.0% compared to 23.8%). In crude and adjusted models, hypertensive women had a 4-fold increased risk of breast cancer (adjusted odds ratio: 4.2; 95% confidence interval: 1.8; 9.6) compared to non-hypertensive women in the entire sample. We found a similar association in the postmenopausal group (adjusted odds ratio: 2.8; 95% confidence interval: 1.1; 7.4). A significant effect was also observed when hypertension was defined as blood pressure of ${\geq}130/85$ mmHg. Conclusion: A significant association was found between hypertension and breast cancer over the entire sample and when restricted to postmenopausal women. Hypertension is highly prevalent in Latin America and may be a modifiable risk factor for breast cancer; therefore, a small association between hypertension and breast cancer may have broad implications.

Evaluation of Lung Preservation by Using of Canine Bilateral Sequential Lung Tranplantation (성견의 연속 양측 폐이식을 이용한 폐보존 평가 연구)

  • 박창권;김재범;유영선;권건영;전석길;김정식
    • Journal of Chest Surgery
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    • v.33 no.5
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    • pp.377-384
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    • 2000
  • Background: Numerous studies of safe, long term preservation for lung transplantation have been performed using ex vivo models or in vivo single lung transplantation models. However, a safe preservation time which is applicable for clinical use is difficult to determine. We prepared LPDG solution for lung preservation study. In this study we examined the efficacy of LPDG(low potassium dextran glucose) solution in 24-hour lung preservation by using a sequential bilateral canine lung allotransplant model. Material and Method: Seven bilateral lung transplant procedures were performed using weight-matched pairs(24 to 25kg) of adult mongrel dogs. The donor lungs were flushed with LPDG solution and maintained hyperinflated with 100% oxygen at 1$0^{\circ}C$ for a planned ischemic time of 24 hours for the lung implanted first. After sequential bilateral lung transplantation, dogs were maintained on ventilators for 3 hours: arterial resistance were determined if the recipients hourly after bilateral reperfusion and compared with pretransplant-recipient values, which were used as controls. After 2hours of reperfusion, the chest X-ray, computed tomogram and lung perfusion scan were performed for assessmint of early graft lung function. Pathological examinations for ultrastructural findings of alveolar structure and endothelial structure of pulmonary artery were performed. Result: Five of seven experiments successfully finished the whole assessments after bilateral reperfusion for three hours. Arterial oxygen tension in the recipients was markedly decrased in immediate reperfusion period but gradually recovered after reperfusion for three hours. The pulmonary artery and pulmonary vascular resistance showed singificant elevation(p<0.05 versus control values) but also recovered after reperfusion for three hours(p<0.05 versus immediate period value). The ultrastructural findings of alveolar structure and endothelial structure of pulmonary artery showed reversible mild injury in 24 hours of lung perservation and reperfusion. Conclusion : This study suggests that LPDG solution provides excellent preservation in a canine model in which the dog is completely dependent on the function of the transplanted lung.

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Circulating folate levels and colorectal adenoma: a case-control study and a meta-analysis

  • Park, Yeong Mi;Youn, Jiyoung;Cho, Chang Ho;Kim, Sung Hi;Lee, Jung Eun
    • Nutrition Research and Practice
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    • v.11 no.5
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    • pp.419-429
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    • 2017
  • BACKGROUND/OBJECTIVES: The relationship between folate and colorectal neoplasia remains controversial. We examined the association between serum folate concentrations and colorectal adenomas in a case-control study of Korean adults and conducted a meta-analysis. SUBJECTS/METHODS: Our case-control study included 113 pairs of case and control who underwent colonoscopy and provided blood samples. We used multivariable conditional logistic regression models to obtain the odds ratios and 95% confidence interval (CIs). For meta-analysis, we identified the relevant studies by searching the PubMed database up to February 2017, included our case-control study and combined the study-specific relative risks (RRs) using a random-effects model. RESULTS: In this case-control study, we included 58 men and 55 women with colorectal adenomas and sex and fasting status matched the controls. We did not find any significant association between the serum folate levels and colorectal adenomas in either men or women. For meta-analysis, a total of eleven studies were included in our analysis and classified into two groups; polyp clearance group (PC) for the studies that included participants who underwent endoscopies and had their polyps removed at baseline; and no polyp clearance group (NPC) for the studies that included participants whose histories of endoscopies were unknown or who underwent their first endoscopies. Four PC (1,311 cases and 1,672 non-cases) and eight NPC studies (3,501 cases and 11,347 non-cases) were included. The combined RRs (95% CIs) comparing the bottom with the top categories of circulating folate levels were 1.07 (0.97-1.18) for the NPC group but 1.45 (1.16-1.74) for the PC group. CONCLUSIONS: Low circulating folate levels were associated with new adenoma formation.

Efficient Geometric Model Reconstruction using Contour Lines (외곽선을 이용한 효율적인 기하모델 재구성 기법)

  • Jung Hoe Sang;Kwon Koo Joo;Shin Byeong-Seok
    • Journal of KIISE:Computer Systems and Theory
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    • v.32 no.8
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    • pp.418-425
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    • 2005
  • 3D surface reconstruction is to make the original geometry of 3D objects from 2D geometric information. Barequet's algorithm is well known and most widely used in surface reconstruction. It tiles matched regions first, then triangulates clefts using dynamic programming. However it takes considerably long processing time while manipulating complex model. Our method tiles a simple region that does not have branches along minimally distant vertex pairs at once. When there are branches, our method divides contour lines into a simple region and clefts. We propose a fast and simple method that calculates medial axes using a minimum distance in cleft region. Experimental results show that our method can produce accurate models than the previous method within short time.