Human Immunodeficiency Virus (HIV) dynamics in Africa are purely characterised by sparse sampling of DNA sequences for individuals who are infected. There are some sub-groups that are more at risk than the general pop...Human Immunodeficiency Virus (HIV) dynamics in Africa are purely characterised by sparse sampling of DNA sequences for individuals who are infected. There are some sub-groups that are more at risk than the general population. These sub-groups have higher infectivity rates. We came up with a likelihood inference model of multi-type birth-death process that can be used to make inference for HIV epidemic in an African setting. We employ a likelihood inference that incorporates a probability of removal from infectious pool in the model. We have simulated trees and made parameter inference on the simulated trees as well as investigating whether the model distinguishes between heterogeneous and homogeneous dynamics. The model makes fairly good parameter inference. It distinguishes between heterogeneous and homogeneous dynamics well. Parameter estimation was also performed under sparse sampling scenario. We investigated whether trees obtained from a structured population are more balanced than those from a non-structured host population using tree statistics that measure tree balance and imbalance. Trees from non-structured population were more balanced basing on Colless and Sackin indices.展开更多
Caesarean is a major surgical procedure undertaken in obstetrics and its rate is increasing in Sri Lanka as well as in the world. In Sri Lanka, health statistics show an increase in caesarean rates from 13.3% in 1998 ...Caesarean is a major surgical procedure undertaken in obstetrics and its rate is increasing in Sri Lanka as well as in the world. In Sri Lanka, health statistics show an increase in caesarean rates from 13.3% in 1998 to 30.6% by 2007. Due to its potential serious risks and the burden on the health system, many authorities have recommended reducing the caesarean rate for many years. This motivated us to study the most influential variables on the type of birth in Sri Lanka. In this study, based on the Anuradhapura Teaching Hospital records, entire 805 new born babies’ birth information was considered during the month of May, 2015. The variable “Type of Birth” (Normal/Caesarean) was considered as a binary response variable and age, height, weight of mother and sex, weight, length, shoulder length, head circumference of the baby were treated as explanatory variables. Logistic regression was used to model the data and using stepwise regression;mother’s age, height and weight were identified as the most influential variables on the type of birth. Further, it was observed that the odds of having normal birth is 80% higher for woman who belongs to the age group less than or equal to 30 years compared to woman who belongs to the age group greater than 30 years. Moreover, the Hosmer-Lemeshow goodness of fit test was used to check the adequacy of the fitted model. Results from this study revealed that in future, the type of birth may be predicted by considering these identified influential variables.展开更多
目的探讨血浆N末端B型钠尿肽前体(N-terminal pro-B-type natriuretic peptide,NTproBNP)在预测中重度支气管肺发育不良(bronchopulmonary dysplasia,BPD)风险中的临床价值。方法采用前瞻观察性研究方法,选择2021年6月—2022年12月福建...目的探讨血浆N末端B型钠尿肽前体(N-terminal pro-B-type natriuretic peptide,NTproBNP)在预测中重度支气管肺发育不良(bronchopulmonary dysplasia,BPD)风险中的临床价值。方法采用前瞻观察性研究方法,选择2021年6月—2022年12月福建省妇幼保健院新生儿科收治的胎龄<30周极/超早产儿95例。分别于出生后第1、7、14、21天检测NTproBNP水平并收集住院期间基本资料,根据美国国家儿童健康与人类发展研究所(National Institute of Child Health and Human Development,NICHD)诊断标准,分为无-轻度BPD组(n=74)和中-重度BPD组(n=21)。比较2组不同时间点NTproBNP水平。结果中-重度BPD组胎龄、出生体质量均低于无-轻度BPD组(P<0.05);中-重度BPD组胎膜早破>18 h、≥3级新生儿呼吸窘迫综合征(respiratory distress syndrome,RDS)、有创机械通气时间>7 d、症状性动脉导管未闭(symptomatic patent ductus arteriosus,sPDA)、晚发型败血症、早产儿视网膜病(retinopathy of prematurity,ROP)的发生率均高于无-轻度BPD组,差异有统计学意义(P<0.05)。无-轻度BPD组NTproBNP水平在出生后第1天最高,中-重度BPD组NTproBNP水平在出生后第7天最高,随后逐渐降低。中-重度BPD组各时间点NTproBNP水平均高于无-轻度BPD组,差异有统计学意义(P<0.05)。出生后第1天NTproBNP水平为5631.52 pg/mL,是中重度BPD最佳预测参考值,受试者工作特征(receiver operating characteristic,ROC)曲线下面积为0.89(95%CI0.83~0.95),诊断准确性为85.71%。结论出生后第1天NTproBNP水平有助于早期预测中重度BPD发病风险,动态监测NTproBNP趋势可能对疾病防治提供一定参考价值。展开更多
This paper aims at two problems which exist in most of repairable spare part demand models at present: the exponential distribution as the basic assumption and one typical distribution corresponding to a model. A gene...This paper aims at two problems which exist in most of repairable spare part demand models at present: the exponential distribution as the basic assumption and one typical distribution corresponding to a model. A general repairable spare part demand model built on quasi birth-and-death process is developed. This model assumes that both the operational time of the unit and the maintenance time of the unit follow the continuous time phase type distributions. The first passage time distribution to be out of spares, the first mean time to be out of spares, and an algorithm to get the minimal amount of spares under certain restrictions are obtained. At the end of this paper, a numerical example is given.展开更多
In this paper, we study the logarithmic Sobolev inequalities for two-sided birth-death processes. An estimate of the logarithmic Sobolev constant α for a two-sided birth-death process is obtained by the Hardy-type in...In this paper, we study the logarithmic Sobolev inequalities for two-sided birth-death processes. An estimate of the logarithmic Sobolev constant α for a two-sided birth-death process is obtained by the Hardy-type inequality and a criteria for a is also presented.展开更多
文摘Human Immunodeficiency Virus (HIV) dynamics in Africa are purely characterised by sparse sampling of DNA sequences for individuals who are infected. There are some sub-groups that are more at risk than the general population. These sub-groups have higher infectivity rates. We came up with a likelihood inference model of multi-type birth-death process that can be used to make inference for HIV epidemic in an African setting. We employ a likelihood inference that incorporates a probability of removal from infectious pool in the model. We have simulated trees and made parameter inference on the simulated trees as well as investigating whether the model distinguishes between heterogeneous and homogeneous dynamics. The model makes fairly good parameter inference. It distinguishes between heterogeneous and homogeneous dynamics well. Parameter estimation was also performed under sparse sampling scenario. We investigated whether trees obtained from a structured population are more balanced than those from a non-structured host population using tree statistics that measure tree balance and imbalance. Trees from non-structured population were more balanced basing on Colless and Sackin indices.
文摘Caesarean is a major surgical procedure undertaken in obstetrics and its rate is increasing in Sri Lanka as well as in the world. In Sri Lanka, health statistics show an increase in caesarean rates from 13.3% in 1998 to 30.6% by 2007. Due to its potential serious risks and the burden on the health system, many authorities have recommended reducing the caesarean rate for many years. This motivated us to study the most influential variables on the type of birth in Sri Lanka. In this study, based on the Anuradhapura Teaching Hospital records, entire 805 new born babies’ birth information was considered during the month of May, 2015. The variable “Type of Birth” (Normal/Caesarean) was considered as a binary response variable and age, height, weight of mother and sex, weight, length, shoulder length, head circumference of the baby were treated as explanatory variables. Logistic regression was used to model the data and using stepwise regression;mother’s age, height and weight were identified as the most influential variables on the type of birth. Further, it was observed that the odds of having normal birth is 80% higher for woman who belongs to the age group less than or equal to 30 years compared to woman who belongs to the age group greater than 30 years. Moreover, the Hosmer-Lemeshow goodness of fit test was used to check the adequacy of the fitted model. Results from this study revealed that in future, the type of birth may be predicted by considering these identified influential variables.
文摘目的探讨血浆N末端B型钠尿肽前体(N-terminal pro-B-type natriuretic peptide,NTproBNP)在预测中重度支气管肺发育不良(bronchopulmonary dysplasia,BPD)风险中的临床价值。方法采用前瞻观察性研究方法,选择2021年6月—2022年12月福建省妇幼保健院新生儿科收治的胎龄<30周极/超早产儿95例。分别于出生后第1、7、14、21天检测NTproBNP水平并收集住院期间基本资料,根据美国国家儿童健康与人类发展研究所(National Institute of Child Health and Human Development,NICHD)诊断标准,分为无-轻度BPD组(n=74)和中-重度BPD组(n=21)。比较2组不同时间点NTproBNP水平。结果中-重度BPD组胎龄、出生体质量均低于无-轻度BPD组(P<0.05);中-重度BPD组胎膜早破>18 h、≥3级新生儿呼吸窘迫综合征(respiratory distress syndrome,RDS)、有创机械通气时间>7 d、症状性动脉导管未闭(symptomatic patent ductus arteriosus,sPDA)、晚发型败血症、早产儿视网膜病(retinopathy of prematurity,ROP)的发生率均高于无-轻度BPD组,差异有统计学意义(P<0.05)。无-轻度BPD组NTproBNP水平在出生后第1天最高,中-重度BPD组NTproBNP水平在出生后第7天最高,随后逐渐降低。中-重度BPD组各时间点NTproBNP水平均高于无-轻度BPD组,差异有统计学意义(P<0.05)。出生后第1天NTproBNP水平为5631.52 pg/mL,是中重度BPD最佳预测参考值,受试者工作特征(receiver operating characteristic,ROC)曲线下面积为0.89(95%CI0.83~0.95),诊断准确性为85.71%。结论出生后第1天NTproBNP水平有助于早期预测中重度BPD发病风险,动态监测NTproBNP趋势可能对疾病防治提供一定参考价值。
基金Supported by National Defense Foundation of P. R. China (41319060206)
文摘This paper aims at two problems which exist in most of repairable spare part demand models at present: the exponential distribution as the basic assumption and one typical distribution corresponding to a model. A general repairable spare part demand model built on quasi birth-and-death process is developed. This model assumes that both the operational time of the unit and the maintenance time of the unit follow the continuous time phase type distributions. The first passage time distribution to be out of spares, the first mean time to be out of spares, and an algorithm to get the minimal amount of spares under certain restrictions are obtained. At the end of this paper, a numerical example is given.
基金the National Natural Science Foundation of China(10271091)
文摘In this paper, we study the logarithmic Sobolev inequalities for two-sided birth-death processes. An estimate of the logarithmic Sobolev constant α for a two-sided birth-death process is obtained by the Hardy-type inequality and a criteria for a is also presented.
