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
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
目的探究孕期不同阴道微生物群落状态类型(community state type,CST)与早产的相关性。方法搜索在PubMed、Web of Science、Elsevier Science Direct、中国知网、万方数据知识服务平台和维普数据库建库至2024年6月公开发表的关于孕期阴...目的探究孕期不同阴道微生物群落状态类型(community state type,CST)与早产的相关性。方法搜索在PubMed、Web of Science、Elsevier Science Direct、中国知网、万方数据知识服务平台和维普数据库建库至2024年6月公开发表的关于孕期阴道CST与早产关系的文献,根据纳入与排除标准筛选文献并提取信息,所得数据使用Revman 5.4及Stata 16.0软件进行统计学分析。结果共纳入13篇队列研究,共计1959例孕妇,涉及经16S rRNA高通量基因测序分析明确的5种阴道CST,4种CST以乳酸杆菌占主导地位,分别为CSTⅠ卷曲乳酸杆菌、CSTⅡ格氏乳酸杆菌、CSTⅢ惰性乳酸杆菌和CSTⅤ詹氏乳酸杆菌,另外1种为CSTⅣ低乳酸杆菌。网状Meta分析结果显示,各CST诱发早产的风险排序由高至低为CSTⅤ>CSTⅣ>CSTⅢ>CSTⅡ>CSTⅠ,各CST两两比较,其导致早产风险的差异无统计学意义。早孕期采样组(采样孕周<14周)中,CSTⅣ与CSTⅠ比较增加了早产风险,差异有统计学意义(P<0.05)。亚裔人群中导致早产高风险菌群高危排序为CSTⅤ>CSTⅡ>CSTⅣ>CSTⅠ>CSTⅢ,各CST组间比较差异无统计学意义。结论当前研究显示,整体孕期各类阴道CST导致早产风险的差异无统计学意义,但亚组分析显示早孕期CSVⅣ较CSTⅠ增加了早产风险,差异有统计学意义。采样孕周及种族等均可能对研究结果产生影响,需要开展更多高质量、大样本量研究,以期探讨阴道CST与早产的相关性。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.
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.
文摘目的探究孕期不同阴道微生物群落状态类型(community state type,CST)与早产的相关性。方法搜索在PubMed、Web of Science、Elsevier Science Direct、中国知网、万方数据知识服务平台和维普数据库建库至2024年6月公开发表的关于孕期阴道CST与早产关系的文献,根据纳入与排除标准筛选文献并提取信息,所得数据使用Revman 5.4及Stata 16.0软件进行统计学分析。结果共纳入13篇队列研究,共计1959例孕妇,涉及经16S rRNA高通量基因测序分析明确的5种阴道CST,4种CST以乳酸杆菌占主导地位,分别为CSTⅠ卷曲乳酸杆菌、CSTⅡ格氏乳酸杆菌、CSTⅢ惰性乳酸杆菌和CSTⅤ詹氏乳酸杆菌,另外1种为CSTⅣ低乳酸杆菌。网状Meta分析结果显示,各CST诱发早产的风险排序由高至低为CSTⅤ>CSTⅣ>CSTⅢ>CSTⅡ>CSTⅠ,各CST两两比较,其导致早产风险的差异无统计学意义。早孕期采样组(采样孕周<14周)中,CSTⅣ与CSTⅠ比较增加了早产风险,差异有统计学意义(P<0.05)。亚裔人群中导致早产高风险菌群高危排序为CSTⅤ>CSTⅡ>CSTⅣ>CSTⅠ>CSTⅢ,各CST组间比较差异无统计学意义。结论当前研究显示,整体孕期各类阴道CST导致早产风险的差异无统计学意义,但亚组分析显示早孕期CSVⅣ较CSTⅠ增加了早产风险,差异有统计学意义。采样孕周及种族等均可能对研究结果产生影响,需要开展更多高质量、大样本量研究,以期探讨阴道CST与早产的相关性。
