In Japan, most sudden deaths occurring during bathing happen in the winter, and predominantly to elderly people. One can infer a relation to physical conditions that are specific to aging. Atrial fibrillation, an arrh...In Japan, most sudden deaths occurring during bathing happen in the winter, and predominantly to elderly people. One can infer a relation to physical conditions that are specific to aging. Atrial fibrillation, an arrhythmia, increases with age. This study examined histological changes in the pulmonary vein myocardial sleeves of sudden bathtub death victims and compared them with those of control individuals. We investigated 35 sudden deaths that occurred during bathing and 34 accidental deaths or deaths caused by diseases unrelated to cardiopathies. Pulmonary veins were excised cross-sectionally from the hilar side to the venoatrial junction. Then they were stained with hematoxylin and eosin, resorcin-fuchsin van Gieson, and Congo-red stains. Amyloid deposits in the pulmonary vein myocardial sleeves, as well as the range and severity of scarring, were graded microscopically on a scale of 0-3. In the sudden bathtub death victims, severe scarring was found in the myocardial sleeves of the four pulmonary veins (mean score, 2.0), which was significantly different (p < 0.05) from the control subjects (mean score, 1.4). Cardiomegaly was found in 28 out of the autopsied individuals. In subjects with cardiomegaly, the mean value of pulmonary vein myocardial sleeve scarring was 2.1. In subjects without cardiomegaly, the mean value was 1.8. Comparison revealed that cardiomegaly was associated significantly with scarring progression and degeneration of the myocardial sleeves. Scarring of the pulmonary vein myocardial sleeves was more advanced in victims of sudden bathtub death than in controls without heart disease. Elderly people with scarring of the pulmonary vein myocardial sleeves are likely to develop degenerative variations in their intra-atrial excitation conduction. These results demonstrate that taking hot baths might induce supraventricular arrhythmias such as atrial fibrillation.展开更多
In this paper, the authors will study the estimation of maintenance efficiency in Arithmetic Reduction of Intensity （ARI） and Arithmetic Reduction of Age （ARA） models with a memory m. These models have been propos...In this paper, the authors will study the estimation of maintenance efficiency in Arithmetic Reduction of Intensity （ARI） and Arithmetic Reduction of Age （ARA） models with a memory m. These models have been proposed by Doyen （2005）, the failure process is simply Non Homogeneous Poisson Process （NHPP）. Our models are defined by reformulation of ARI and ARA ones using bathtub failure intensity. This form is presented like a superposition of two NHPP and Homogeneous Poisson Process （HPP）. Moreover, the particularity of this model allows taking account of system state improvement in time course. The maintenance effect is characterized by the change induced on the failure intensity before and after failure during degradation period. To simplify study, the asymptotic properties of failure process are derived. Then, the asymptotic normality of several maintenance efficiency estimators can be proved in the case where the failure process without maintenance is known. Practically, the coverage rate of the asymptotic confidence intervals issued from those estimators is studied.展开更多
In this article,an additive Perks—Weibull model capable of modeling life-time data with bathtub-shaped hazard rate function is proposed.The model is derivedby the sum of the hazard rates of Perks and Weibull distribu...In this article,an additive Perks—Weibull model capable of modeling life-time data with bathtub-shaped hazard rate function is proposed.The model is derivedby the sum of the hazard rates of Perks and Weibull distributions.Some statisticalproperties including shapes of density and hazard rate functions,moments,and orderstatistics are explored.The method of maximum likelihood estimation is used for esti-mating the model parameters.The goodness-of-fit of the model for three real datasetshaving bathtub-shaped hazard rate functions has been illustrated.Finally,an appli-cation for competing risk data is also given to show the flexibility of the proposedmodel.展开更多
文摘In Japan, most sudden deaths occurring during bathing happen in the winter, and predominantly to elderly people. One can infer a relation to physical conditions that are specific to aging. Atrial fibrillation, an arrhythmia, increases with age. This study examined histological changes in the pulmonary vein myocardial sleeves of sudden bathtub death victims and compared them with those of control individuals. We investigated 35 sudden deaths that occurred during bathing and 34 accidental deaths or deaths caused by diseases unrelated to cardiopathies. Pulmonary veins were excised cross-sectionally from the hilar side to the venoatrial junction. Then they were stained with hematoxylin and eosin, resorcin-fuchsin van Gieson, and Congo-red stains. Amyloid deposits in the pulmonary vein myocardial sleeves, as well as the range and severity of scarring, were graded microscopically on a scale of 0-3. In the sudden bathtub death victims, severe scarring was found in the myocardial sleeves of the four pulmonary veins (mean score, 2.0), which was significantly different (p < 0.05) from the control subjects (mean score, 1.4). Cardiomegaly was found in 28 out of the autopsied individuals. In subjects with cardiomegaly, the mean value of pulmonary vein myocardial sleeve scarring was 2.1. In subjects without cardiomegaly, the mean value was 1.8. Comparison revealed that cardiomegaly was associated significantly with scarring progression and degeneration of the myocardial sleeves. Scarring of the pulmonary vein myocardial sleeves was more advanced in victims of sudden bathtub death than in controls without heart disease. Elderly people with scarring of the pulmonary vein myocardial sleeves are likely to develop degenerative variations in their intra-atrial excitation conduction. These results demonstrate that taking hot baths might induce supraventricular arrhythmias such as atrial fibrillation.
文摘In this paper, the authors will study the estimation of maintenance efficiency in Arithmetic Reduction of Intensity （ARI） and Arithmetic Reduction of Age （ARA） models with a memory m. These models have been proposed by Doyen （2005）, the failure process is simply Non Homogeneous Poisson Process （NHPP）. Our models are defined by reformulation of ARI and ARA ones using bathtub failure intensity. This form is presented like a superposition of two NHPP and Homogeneous Poisson Process （HPP）. Moreover, the particularity of this model allows taking account of system state improvement in time course. The maintenance effect is characterized by the change induced on the failure intensity before and after failure during degradation period. To simplify study, the asymptotic properties of failure process are derived. Then, the asymptotic normality of several maintenance efficiency estimators can be proved in the case where the failure process without maintenance is known. Practically, the coverage rate of the asymptotic confidence intervals issued from those estimators is studied.
基金the critical suggestions from the learned refereesand editorial board which greatly helped in the improvement of the paper.
文摘In this article,an additive Perks—Weibull model capable of modeling life-time data with bathtub-shaped hazard rate function is proposed.The model is derivedby the sum of the hazard rates of Perks and Weibull distributions.Some statisticalproperties including shapes of density and hazard rate functions,moments,and orderstatistics are explored.The method of maximum likelihood estimation is used for esti-mating the model parameters.The goodness-of-fit of the model for three real datasetshaving bathtub-shaped hazard rate functions has been illustrated.Finally,an appli-cation for competing risk data is also given to show the flexibility of the proposedmodel.
