Objectives: Current study sought to determine an association between Low Birth Weight (LBW) and early neonatal mortality at a resource limited country’s referral hospital and to determine relationship between materna...Objectives: Current study sought to determine an association between Low Birth Weight (LBW) and early neonatal mortality at a resource limited country’s referral hospital and to determine relationship between maternal age and birth outcomes. Method: A retrospective study analyzing data on births in the Volta Regional Hospital, Ghana from the period of November 2011 to June 2016. A total of 8279 births were analyzed. Results: Results suggest that teenage mothers (8.60%) are more likely to give birth to pre-term babies than the elderly (6.60%) and the adult mothers (4.61%). LBW is highest among the teenage mothers (12.69%) followed by the elderly mothers (7.87%) and then the least among the adult mothers (6.48%). Extremely Low Birth Weight (ELBW) and Macrosomia births were more observed among the elderly mothers (0.90%;2.17%) than the teenage (0.28%;0.14%) and adult mothers (0.34%;1.61%) respectively. Data suggest that 100% of the ELBW were pre-term birth, 88.28% Very Low Birth Weight (VLBW), 34.56% LBW and only 1.06% of the pre-term birth were with Normal Birth Weight (NBW). Death rate ranges from 50% for ELBW, 33.59% for VLBW, 8.22% for LBW, 5.43% for Macrosomia and 1.5% for NBW. However, death rate distribution among the various age groups was statistically not significant (P 0.106). Conclusions: Our study suggests that early neonatal death, especially deaths among ELBW and VLBW is still high at the VRH of Ghana and therefore there is the need for further studies into interventions to reduce death among neonates born with VLBW and ELBW.展开更多
In this paper,we provide a general method to obtain the exact solutions of the degree distributions for random birthand-death network(RBDN) with network size decline.First,by stochastic process rules,the steady stat...In this paper,we provide a general method to obtain the exact solutions of the degree distributions for random birthand-death network(RBDN) with network size decline.First,by stochastic process rules,the steady state transformation equations and steady state degree distribution equations are given in the case of m ≥ 3 and 0 〈 p 〈 1/2,then the average degree of network with n nodes is introduced to calculate the degree distributions.Specifically,taking m = 3 for example,we explain the detailed solving process,in which computer simulation is used to verify our degree distribution solutions.In addition,the tail characteristics of the degree distribution are discussed.Our findings suggest that the degree distributions will exhibit Poisson tail property for the declining RBDN.展开更多
An aggregation growth model of three species A, B and C with the competition between catalyzed birth and catalyzed death is proposed. Irreversible aggregation occurs between any two aggregates of the like species with...An aggregation growth model of three species A, B and C with the competition between catalyzed birth and catalyzed death is proposed. Irreversible aggregation occurs between any two aggregates of the like species with theconstant rate kernels In(n = 1,2, 3). Meanwhile, a monomer birth of an A species aggregate of size k occurs under the catalysis of a B species aggregate of size j with the catalyzed birth rate kernel K(k, j) = Kkj^v, and a monomer death of an A species aggregate of size k occurs under the catalysis of a C species aggregate of size j with the catalyzed death rate kernel L(k, j) = Lkj^v, whcre v is a parameter reflecting the dependence of the catalysis reaction rates of birth and death on the size of catalyst aggregate. The kinetic evolution behaviours of the three species are investigated by the rate equation approach based on the mean-field theory. The form of the aggregate size distribution of A species ak (t) is found to be dependent crucially on the competition between the catalyzed birth and death of A species, as well as the irreversible aggregation processes of the three species: (i) In the v 〈 0 case, the irreversible aggregation dominates the process, and ak(t) satisfies the conventional scaling form; (2) In the v ≥ 0 casc, the competition between the catalyzed birth and death dominates the process. When the catalyzed birth controls the process, ak(t) takes the conventional or generalized scaling form. While the catalyzed death controls the process, the scaling description of the aggregate size distribution breaks down completely.展开更多
A finite random graph generated by continuous time birth and death processes with exponentially distributed waiting times was investigated, which is similar to a communication network in daily life. The vertices are t...A finite random graph generated by continuous time birth and death processes with exponentially distributed waiting times was investigated, which is similar to a communication network in daily life. The vertices are the living particles, and directed edges go from mothers to daughters. The size of the communication network was studied. Furthermore, the probability of successfully connecting senders with receivers and the transmitting speed of information were obtained.展开更多
We propose a two-species infection model, in which an infected aggregate can gain one monomer from a healthy one due to infection when they meet together. Moreover, both the healthy and infected aggregates may lose on...We propose a two-species infection model, in which an infected aggregate can gain one monomer from a healthy one due to infection when they meet together. Moreover, both the healthy and infected aggregates may lose one monomer because of self-death, but a healthy aggregate can spontaneously yield a new monomer. Consider a simple system in which the birth/death rates are directly proportional to the aggregate size, namely, the birth and death rates of the healthy aggregate of size k are J1 k and J2k while the self-death rate of the infected aggregate of size k is J3k. We then investigate the kinetics of such a system by means of rate equation approach. For the J1 〉 J2 case, the aggregate size distribution of either species approaches the generalized scaling form and the typical size of either species increases wavily at large times. For the J1 = J2 case, the size distribution of healthy aggregates approaches the generalized scaling form while that of infected aggregates satisfies the modified scaling form. For the J1 〈 J2 case, the size distribution of healthy aggregates satisfies the modified scaling form, but that of infected aggregates does not scale.展开更多
Background: It is yet a controversy subject whether low birth weight and infant death are associated to human immunodeficiency virus-1 infection. Objective: To appreciate association between low birth weights, mother ...Background: It is yet a controversy subject whether low birth weight and infant death are associated to human immunodeficiency virus-1 infection. Objective: To appreciate association between low birth weights, mother to child HIV transmission and infant mortality in HIV-1 infected pregnant women delivering between 2011 and 2016. Materials: We conducted 6 years cohort study in urban Mali. Outcome included preterm delivery, small for gestational age, infant survival status and HIV transmission. Comparison concerned women clinical WHO stage, mother viro-immunological status, and newborn anthropometric parameters. Results: HIV-1 infected women who delivered low birth weight newborn were 20.9% (111/531) versus 16.5% (1910/11.546) in HIV negative patients (p = 0.016). CD4 T cell counts low than 350 T cells count were strongly associated to LBW (p = 0.000;RR = 3.03;95% CI [1.89 - 3.16]). There is no significant association between ART that was initiated during pregnancy (p = 0.061, RR = 0.02;CI 95% (1.02 - 1.99)) or during delivery (p = 0.571;RR = 1.01;CI 95% (0.10 - 3.02)) and LBW delivery. In multivariate analysis ART regimens containing protease inhibitor (PI) were lone regimens associated with LBW ((p = 0.030;RR = 1.001;95% confidence interval [1.28 - 3.80]). Very low birth weight was statistically associated to women HIV infection (adjusted relative risk, 2.02;p = 0.000;95% confidence interval (2.17 - 4.10)). There is no significant difference between mother to child HIV transmission rate in the two HIV-infected pregnant women (10 infected children in group 2: MTCT rate 4.5%) and 3 infected children in group 1 (MTCT rate: 2.7%) (p = 0.56;RR, 0.59;CI 95% (0.18 - 4.39)). In multivariate analysis, LBW was associated with infant death (p = 0.001;RR = 2.04;CI 95% [1.04 - 5.05]). The median weight of infant at the moment of death in group 1 was 851 g (IQR: 520 - 1833 g). Significant relationship was found between infant death among LBW newborn with mother WHO stage 2 (p = 0.004;adjusted RR = 3.22;CI 95% [2.25 - 6.00]), CD4 T cells count 3 (p = 0.005;RR = 2.81;CI 95% [1.20 - 4.11]), PI regimens (p = 0.030;RR = 1.00;CI 95% [1.28 - 3.80]). Conclusion: We confirm increased risk of low birth weight and mother HIV-1 infection and we identified strongest association between mortality in infant born to HIV-1 infected mother and LBW.展开更多
Introduction: Our aim was to identify the risk factors of clinical birth asphyxia and subsequent newborn death in the presence of nuchal cord in a sub-Saharan Africa setting. Methodology: It was a six-months’ case-co...Introduction: Our aim was to identify the risk factors of clinical birth asphyxia and subsequent newborn death in the presence of nuchal cord in a sub-Saharan Africa setting. Methodology: It was a six-months’ case-control study involving 117 parturients whose babies presented with a nuchal cord at delivery. The study was carried out at the Yaoundé Gyneco-Obstetric and Pediatric Hospital, Cameroon, from January 1st to June 30th 2013. Results: The risk factors of clinical birth asphyxia identified were: first delivery, absence of obstetrical ultrasound during pregnancy, nuchal cord with more than one loop, duration of second stage of labor more than 30 minutes during vaginal delivery. The risk factors for newborn death from clinical birth asphyxia in the presence of nuchal cord were: maternal age Conclusion: We recommend a systematic obstetrical ultrasound before labor, so as to detect the presence of a nuchal cord, its tightness and the number of loops. Also, cesarean section should be considered when a nuchal cord is associated with first delivery, tightness or multiple looping.展开更多
Introduction: Indicators of maternal health are often used to evaluate the social development and overall health of a population, as well as the accessibility of health services. Among these indicators, the Potential ...Introduction: Indicators of maternal health are often used to evaluate the social development and overall health of a population, as well as the accessibility of health services. Among these indicators, the Potential Years of Life Lost, which is associated with maternal deaths, is useful for the definition of priorities, monitoring, evaluation, and intervention, identifying the highest risk groups. Objective: To analyze the Potential Years of Life Lost by maternal death in Santa Catarina in 2000 and 2014. Method: An Ecological study with exploratory spatial analysis was conducted with data obtained from the Information System on Mortality and Live Births. Results: In the Information System, 35 maternal deaths in the year 2000 were identified and 24 in 2014. The total estimated years of life lost were 845 years in 2000 and 780 years in 2014, dominated by direct obstetric causes. In 2000, women who died lost, on average, 39.8 years of life;and 41.5 years in 2014. Conclusion: The spatial pattern observed in 2000 highlights areas of high risk in different regions of Santa Catarina. The greatest loss of years occurred in younger women, confirming the need to prevent and control maternal mortality and review strategies for compliance with public policies in the State.展开更多
The concepts of bi-immigration birth and death density matrix in random environment and bi-immigration birth and death process in random environment are introduced. For any bi-immigration birth and death matrix in ran...The concepts of bi-immigration birth and death density matrix in random environment and bi-immigration birth and death process in random environment are introduced. For any bi-immigration birth and death matrix in random environment Q(θ) with birth rate λ 〈 death rate μ, the following results are proved, (1) there is an unique q-process in random environment, P^-(θ*(0);t) = (p^-(θ^*(0);t,i,j),i,j ≥ 0), which is ergodic, that is, lim t→∞(θ^*(0);t,i,j) = π^-(θ^*(0);j) ≥0 does not depend on i ≥ 0 and ∑j≥0π (θ*(0);j) = 1, (2) there is a bi-immigration birth and death process in random enjvironment (X^* = {X^*,t ≥ 0},ε^* = {εt,t ∈ (-∞, ∞)}) with random transition matrix P^-(θ^* (0);t) such that X^* is a strictly stationary process.展开更多
Taking the tobacco-growing area of Shashi Town,Liuyang City as the object,the number of registered,newly added and resigned tobacco farmers in each year,average age,number and proportion of tobacco farmers of differen...Taking the tobacco-growing area of Shashi Town,Liuyang City as the object,the number of registered,newly added and resigned tobacco farmers in each year,average age,number and proportion of tobacco farmers of different ages,number and proportion of tobacco farmers born in different eras,as well as planting scale and planting history of flue-cured tobacco in the last 10 years were analyzed statistically.The results showed that the number of tobacco farmers in Shashi Town showed a rapid decline trend from 2012 to 2018,while the average age continuously increased,and the average planting scale rose in a wave like way.From 2019 to 2021,the decline rate of the number of tobacco farmers slowed down,and the average planting scale continuously increased,while the aging of tobacco farmers accelerated.Meantime,the birth years of tobacco farmers were further concentrated in the 1960s,and they were mainly at the age of 50-59.The tobacco industry in Shashi Town of Liuyang City is facing the crisis of aging tobacco farmers and no successor of flue-cured tobacco planting,and it is predicted that the next 5-10 years will continue the change trend from 2019 to 2021.展开更多
BACKGROUND Nonalcoholic fatty liver disease(NAFLD)has become the leading cause of cirrhosis and other chronic liver diseases(COCLDs).AIM To conduct a comprehensive and comparable updated analysis of the global,regiona...BACKGROUND Nonalcoholic fatty liver disease(NAFLD)has become the leading cause of cirrhosis and other chronic liver diseases(COCLDs).AIM To conduct a comprehensive and comparable updated analysis of the global,regional,and national burden of COCLDs due to NAFLD in 204 countries and territories from 1990 and 2019 by age,sex,and sociodemographic index.METHODS Data on COCLDs due to NAFLD were collected from the Global Burden of Diseases,Injuries,and Risk Factors Study 2019.Numbers and age-standardized prevalence,death,and disability-adjusted life years(DALYs)were estimated through a systematic analysis of modelled data from the Global Burden of Diseases,Injuries,and Risk Factors Study 2019.The estimated annual percentage change was used to determine the burden trend.RESULTS In 2019,the global age-standardized prevalence rate of COCLDs due to NAFLD was 15022.90 per 100000 population[95%uncertainty interval(UI):13493.19-16764.24],which increased by 24.51%(22.63%to 26.08%)from 1990,with an estimated annual percentage change of 0.78(95%confidence interval:0.74-0.82).In the same year,however,the age-standardized death rate and age-standardized DALYs per 100000 population were 1.66(95%UI:1.20-2.17)and 43.69(95%UI:31.28-58.38),respectively.North Africa and the Middle East had the highest prevalence rates of COCLDs due to NAFLD.The death rate increased with age up to the 95+age group for both sexes.Males had higher numbers of prevalence,death rate,and DALYs than females across all age groups before the 65-69 age group.The sociodemographic index was negatively correlated with the age-standardized DALYs.CONCLUSION Globally,the age-standardized prevalence rate has increased during the past three decades.However,the agestandardized death rate and age-standardized DALYs decreased.There is geographical variation in the burden of COCLDs due to NAFLD.It is strongly recommended to improve the data quality of COCLDs due to NAFLD across all countries and regions to facilitate better monitoring of the burden of COCLDs due to NAFLD.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
At first, the concept of bridge reliability is given, followed with its mathematic model. Then, based on the analysis about the mechanism of the damage and repair of bridges, and the state diversion of bridge network,...At first, the concept of bridge reliability is given, followed with its mathematic model. Then, based on the analysis about the mechanism of the damage and repair of bridges, and the state diversion of bridge network, the state diversion process is proved to be birth-and-death process. In the end, the state diversion balance equation of bridge network is built, and the evaluation model of wartime bridge reliability is got. The model is used in a certain example, and it is proved to be precise and credible.展开更多
In this paper, we propose an SIRS epidemic model with pulse vaccination, birth pulse and Logistic death rate. By using the stroboscopic map of a discrete dynamical system, the disease-free periodic solution (DFPS for ...In this paper, we propose an SIRS epidemic model with pulse vaccination, birth pulse and Logistic death rate. By using the stroboscopic map of a discrete dynamical system, the disease-free periodic solution (DFPS for short) of the model under pulse vaccination and birth pulse is obtained. Based on the Floquet theory and comparison theorem of impulsive differential equations, the global asymptotic stability of the DFPS is given, and sufficient conditions for the permanence of the model are obtained. In addition, numerical simulations are done to confirm our theoretical results.展开更多
It has been hypothesized that during the last several decades human sperm count has declined because of prenatal exposure to environmental chemicals. We examined the relation between semen quality and birth year among...It has been hypothesized that during the last several decades human sperm count has declined because of prenatal exposure to environmental chemicals. We examined the relation between semen quality and birth year among 8608 men born from 1922 to 1971 and who from 1968 to 1992 consulted 4 Danish medical centers because of barren marriage. Data were obtained from medical records and by a postal questionnaire to a subset of the population. The sperm concentration was significantly declining with increasing year of birth in 2 of the 4 centers, but this association disappeared when confounders were adjusted for. Within the subset of men born during 1955~1970 comprising 36% of the entire population we revealed a decrease of the average sperm concentration by 1.6 million /ml (95% CI:0.7~2.5) per one advancing year of birth.This finding was consistent across all the 4 centers and robust to adjustment for effects of calendar period, season and duration of sexual abstinence. Effects of age were accounted for by restriction of the sample to men between 20 and 45 years. The findings are compatible with environmental impact in the prenatal period after 1955 but are far from unequivocal evidence that the sperm count in the general male Danish population has changed during the past decades.展开更多
In this paper, we investigate the dynamical behaviour of entanglement in terms of concurrence in a bipartite system subjected to an external magnetic field under the action of dissipative environments in the extended ...In this paper, we investigate the dynamical behaviour of entanglement in terms of concurrence in a bipartite system subjected to an external magnetic field under the action of dissipative environments in the extended Werner-like initial state. The interesting phenomenon of entanglement sudden death as well as sudden birth appears during the evolution process. We analyse in detail the effect of the purity of the initial entangled state of two qubits via Heisenberg XY interaction on the apparition time of entanglement sudden death and entanglement sudden birth. Furthermore, the conditions on the conversion of entanglement sudden death and entanglement sudden birth can be generalized when the initial entangled state is not pure. In particular, a critical purity of the initial mixed entangled state exists, above which entanglement sudden birth vanishes while entanglement sudden death appears. It is also noticed that stable entanglement, which is independent of different initial states of the qubits (pure or mixed state), occurs even in the presence of decoherence. These results arising from the combination of the extended Werner-like initial state and dissipative environments suggest an approach to control and enhance the entanglement even after purity induced sudden birth, death and revival.展开更多
In recent years some interrelationships between time of birth and longevity were published. Concomitant publications appeared demonstrating links between Space Weather and the timing of medical events;in part of both ...In recent years some interrelationships between time of birth and longevity were published. Concomitant publications appeared demonstrating links between Space Weather and the timing of medical events;in part of both these studies it was shown that Space Weather indices are stronger connected with the time of conception as with the birth time. The aim of these study was to consider birth and conception month of patients suffering from a number of “big killer” pathologies, affecting human longevity and comparing with published data on centenarians—100 - 112 years old persons in the USA. Patients and Methods: We included monthly births distribution of our four papers including patients with Acute Myocardial Infarction undergoing Percutaneous Coronary Intervention (PCI)—n-3765, and admitted in another tertiary medical facility for AMI—n-22,047, and, also patients suffering Rapid—n-1239 and Sudden Cardiac Death—n-327 and, also, patients with oncologic malignancies—n-44587. At all in this group 71,965 patients were included. Their birth and conception months were compared with analogical data of 1574 people of 100 - 112 years old using data of L.A. and N.S. Gavrilov for USA centenarians. Results: The birth months of the cardiovascular and oncology patients were maximal in January, March and April (above 10% at each of these months);their conception was maximal in April, June and July. The monthly distribution of conception and birth of the studied population is presented in Tables 1-3. The maximal birth months of the centenarians were November, September, and October;the maximal conception months were December, January, and February. Conclusion: People suffering Myocardial Infarction, Sudden Cardiac Death and Oncologic Malignancies are in higher numbers born in the first four months of the year and conception in April, June and July. The maximal birth months of the very old people were November, September and October and conception were December, January and February.展开更多
We propose a monomer birth-death model with random removals, in which an aggregate of size k can produce a new monomer at a time-dependent rate I(t)k or lose one monomer at a rate J(t)k, and with a probability P(...We propose a monomer birth-death model with random removals, in which an aggregate of size k can produce a new monomer at a time-dependent rate I(t)k or lose one monomer at a rate J(t)k, and with a probability P(t) an aggregate of any size is randomly removed. We then anedytically investigate the kinetic evolution of the model by means of the rate equation. The results show that the scaling behavior of the aggregate size distribution is dependent crucially on the net birth rate I(t) - J(t) as well as the birth rate I(t). The aggregate size distribution can approach a standard or modified scaling form in some cases, but it may take a scale-free form in other cases. Moreover, the species can survive finally only if either I(t) - J(t) ≥ P(t) or [J(t) + P(t) - I(t)]t ≈ 0 at t ≥ 1; otherwise, it will become extinct.展开更多
A new stochastic epidemic model, that is, a general continuous time birth and death chain model, is formulated based on a deterministic model including vaccination. We use continuous time Markov chain to construct the...A new stochastic epidemic model, that is, a general continuous time birth and death chain model, is formulated based on a deterministic model including vaccination. We use continuous time Markov chain to construct the birth and death process. Through the Kolmogorov forward equation and the theory of moment generating function, the corresponding population expectations are studied. The theoretical result of the stochastic model and deterministic version is also given. Finally, numerical simulations are carried out to substantiate the theoretical results of random walk.展开更多
formula of simulation proccss by In this paper, we employ monmnt generating function to obtain some exact transition probability of inlmigration-birth-death(IBD) model and discuss the of sample path and statistical ...formula of simulation proccss by In this paper, we employ monmnt generating function to obtain some exact transition probability of inlmigration-birth-death(IBD) model and discuss the of sample path and statistical inference with complete observations of the IBD the exact transition density formula.展开更多
文摘Objectives: Current study sought to determine an association between Low Birth Weight (LBW) and early neonatal mortality at a resource limited country’s referral hospital and to determine relationship between maternal age and birth outcomes. Method: A retrospective study analyzing data on births in the Volta Regional Hospital, Ghana from the period of November 2011 to June 2016. A total of 8279 births were analyzed. Results: Results suggest that teenage mothers (8.60%) are more likely to give birth to pre-term babies than the elderly (6.60%) and the adult mothers (4.61%). LBW is highest among the teenage mothers (12.69%) followed by the elderly mothers (7.87%) and then the least among the adult mothers (6.48%). Extremely Low Birth Weight (ELBW) and Macrosomia births were more observed among the elderly mothers (0.90%;2.17%) than the teenage (0.28%;0.14%) and adult mothers (0.34%;1.61%) respectively. Data suggest that 100% of the ELBW were pre-term birth, 88.28% Very Low Birth Weight (VLBW), 34.56% LBW and only 1.06% of the pre-term birth were with Normal Birth Weight (NBW). Death rate ranges from 50% for ELBW, 33.59% for VLBW, 8.22% for LBW, 5.43% for Macrosomia and 1.5% for NBW. However, death rate distribution among the various age groups was statistically not significant (P 0.106). Conclusions: Our study suggests that early neonatal death, especially deaths among ELBW and VLBW is still high at the VRH of Ghana and therefore there is the need for further studies into interventions to reduce death among neonates born with VLBW and ELBW.
基金Project supported by the National Natural Science Foundation of China(Grant No.61273015)the Chinese Scholarship Council
文摘In this paper,we provide a general method to obtain the exact solutions of the degree distributions for random birthand-death network(RBDN) with network size decline.First,by stochastic process rules,the steady state transformation equations and steady state degree distribution equations are given in the case of m ≥ 3 and 0 〈 p 〈 1/2,then the average degree of network with n nodes is introduced to calculate the degree distributions.Specifically,taking m = 3 for example,we explain the detailed solving process,in which computer simulation is used to verify our degree distribution solutions.In addition,the tail characteristics of the degree distribution are discussed.Our findings suggest that the degree distributions will exhibit Poisson tail property for the declining RBDN.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10275048 and 10305009)the Zhejiang Provincial Natural Science Foundation of China (Grant No 102067)
文摘An aggregation growth model of three species A, B and C with the competition between catalyzed birth and catalyzed death is proposed. Irreversible aggregation occurs between any two aggregates of the like species with theconstant rate kernels In(n = 1,2, 3). Meanwhile, a monomer birth of an A species aggregate of size k occurs under the catalysis of a B species aggregate of size j with the catalyzed birth rate kernel K(k, j) = Kkj^v, and a monomer death of an A species aggregate of size k occurs under the catalysis of a C species aggregate of size j with the catalyzed death rate kernel L(k, j) = Lkj^v, whcre v is a parameter reflecting the dependence of the catalysis reaction rates of birth and death on the size of catalyst aggregate. The kinetic evolution behaviours of the three species are investigated by the rate equation approach based on the mean-field theory. The form of the aggregate size distribution of A species ak (t) is found to be dependent crucially on the competition between the catalyzed birth and death of A species, as well as the irreversible aggregation processes of the three species: (i) In the v 〈 0 case, the irreversible aggregation dominates the process, and ak(t) satisfies the conventional scaling form; (2) In the v ≥ 0 casc, the competition between the catalyzed birth and death dominates the process. When the catalyzed birth controls the process, ak(t) takes the conventional or generalized scaling form. While the catalyzed death controls the process, the scaling description of the aggregate size distribution breaks down completely.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10471088, 60572126)
文摘A finite random graph generated by continuous time birth and death processes with exponentially distributed waiting times was investigated, which is similar to a communication network in daily life. The vertices are the living particles, and directed edges go from mothers to daughters. The size of the communication network was studied. Furthermore, the probability of successfully connecting senders with receivers and the transmitting speed of information were obtained.
基金National Natural Science Foundation of China under Grant Nos.10775104 and 10305009
文摘We propose a two-species infection model, in which an infected aggregate can gain one monomer from a healthy one due to infection when they meet together. Moreover, both the healthy and infected aggregates may lose one monomer because of self-death, but a healthy aggregate can spontaneously yield a new monomer. Consider a simple system in which the birth/death rates are directly proportional to the aggregate size, namely, the birth and death rates of the healthy aggregate of size k are J1 k and J2k while the self-death rate of the infected aggregate of size k is J3k. We then investigate the kinetics of such a system by means of rate equation approach. For the J1 〉 J2 case, the aggregate size distribution of either species approaches the generalized scaling form and the typical size of either species increases wavily at large times. For the J1 = J2 case, the size distribution of healthy aggregates approaches the generalized scaling form while that of infected aggregates satisfies the modified scaling form. For the J1 〈 J2 case, the size distribution of healthy aggregates satisfies the modified scaling form, but that of infected aggregates does not scale.
文摘Background: It is yet a controversy subject whether low birth weight and infant death are associated to human immunodeficiency virus-1 infection. Objective: To appreciate association between low birth weights, mother to child HIV transmission and infant mortality in HIV-1 infected pregnant women delivering between 2011 and 2016. Materials: We conducted 6 years cohort study in urban Mali. Outcome included preterm delivery, small for gestational age, infant survival status and HIV transmission. Comparison concerned women clinical WHO stage, mother viro-immunological status, and newborn anthropometric parameters. Results: HIV-1 infected women who delivered low birth weight newborn were 20.9% (111/531) versus 16.5% (1910/11.546) in HIV negative patients (p = 0.016). CD4 T cell counts low than 350 T cells count were strongly associated to LBW (p = 0.000;RR = 3.03;95% CI [1.89 - 3.16]). There is no significant association between ART that was initiated during pregnancy (p = 0.061, RR = 0.02;CI 95% (1.02 - 1.99)) or during delivery (p = 0.571;RR = 1.01;CI 95% (0.10 - 3.02)) and LBW delivery. In multivariate analysis ART regimens containing protease inhibitor (PI) were lone regimens associated with LBW ((p = 0.030;RR = 1.001;95% confidence interval [1.28 - 3.80]). Very low birth weight was statistically associated to women HIV infection (adjusted relative risk, 2.02;p = 0.000;95% confidence interval (2.17 - 4.10)). There is no significant difference between mother to child HIV transmission rate in the two HIV-infected pregnant women (10 infected children in group 2: MTCT rate 4.5%) and 3 infected children in group 1 (MTCT rate: 2.7%) (p = 0.56;RR, 0.59;CI 95% (0.18 - 4.39)). In multivariate analysis, LBW was associated with infant death (p = 0.001;RR = 2.04;CI 95% [1.04 - 5.05]). The median weight of infant at the moment of death in group 1 was 851 g (IQR: 520 - 1833 g). Significant relationship was found between infant death among LBW newborn with mother WHO stage 2 (p = 0.004;adjusted RR = 3.22;CI 95% [2.25 - 6.00]), CD4 T cells count 3 (p = 0.005;RR = 2.81;CI 95% [1.20 - 4.11]), PI regimens (p = 0.030;RR = 1.00;CI 95% [1.28 - 3.80]). Conclusion: We confirm increased risk of low birth weight and mother HIV-1 infection and we identified strongest association between mortality in infant born to HIV-1 infected mother and LBW.
文摘Introduction: Our aim was to identify the risk factors of clinical birth asphyxia and subsequent newborn death in the presence of nuchal cord in a sub-Saharan Africa setting. Methodology: It was a six-months’ case-control study involving 117 parturients whose babies presented with a nuchal cord at delivery. The study was carried out at the Yaoundé Gyneco-Obstetric and Pediatric Hospital, Cameroon, from January 1st to June 30th 2013. Results: The risk factors of clinical birth asphyxia identified were: first delivery, absence of obstetrical ultrasound during pregnancy, nuchal cord with more than one loop, duration of second stage of labor more than 30 minutes during vaginal delivery. The risk factors for newborn death from clinical birth asphyxia in the presence of nuchal cord were: maternal age Conclusion: We recommend a systematic obstetrical ultrasound before labor, so as to detect the presence of a nuchal cord, its tightness and the number of loops. Also, cesarean section should be considered when a nuchal cord is associated with first delivery, tightness or multiple looping.
基金financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nível Superior-Brasil(CAPES)-Finance Code 001.
文摘Introduction: Indicators of maternal health are often used to evaluate the social development and overall health of a population, as well as the accessibility of health services. Among these indicators, the Potential Years of Life Lost, which is associated with maternal deaths, is useful for the definition of priorities, monitoring, evaluation, and intervention, identifying the highest risk groups. Objective: To analyze the Potential Years of Life Lost by maternal death in Santa Catarina in 2000 and 2014. Method: An Ecological study with exploratory spatial analysis was conducted with data obtained from the Information System on Mortality and Live Births. Results: In the Information System, 35 maternal deaths in the year 2000 were identified and 24 in 2014. The total estimated years of life lost were 845 years in 2000 and 780 years in 2014, dominated by direct obstetric causes. In 2000, women who died lost, on average, 39.8 years of life;and 41.5 years in 2014. Conclusion: The spatial pattern observed in 2000 highlights areas of high risk in different regions of Santa Catarina. The greatest loss of years occurred in younger women, confirming the need to prevent and control maternal mortality and review strategies for compliance with public policies in the State.
基金Supported by the NNSF of China (10371092,10771185) the Foundation of Whuan University
文摘The concepts of bi-immigration birth and death density matrix in random environment and bi-immigration birth and death process in random environment are introduced. For any bi-immigration birth and death matrix in random environment Q(θ) with birth rate λ 〈 death rate μ, the following results are proved, (1) there is an unique q-process in random environment, P^-(θ*(0);t) = (p^-(θ^*(0);t,i,j),i,j ≥ 0), which is ergodic, that is, lim t→∞(θ^*(0);t,i,j) = π^-(θ^*(0);j) ≥0 does not depend on i ≥ 0 and ∑j≥0π (θ*(0);j) = 1, (2) there is a bi-immigration birth and death process in random enjvironment (X^* = {X^*,t ≥ 0},ε^* = {εt,t ∈ (-∞, ∞)}) with random transition matrix P^-(θ^* (0);t) such that X^* is a strictly stationary process.
基金Supported by Science and Technology Project of Changsha Tobacco Company(20-22B02).
文摘Taking the tobacco-growing area of Shashi Town,Liuyang City as the object,the number of registered,newly added and resigned tobacco farmers in each year,average age,number and proportion of tobacco farmers of different ages,number and proportion of tobacco farmers born in different eras,as well as planting scale and planting history of flue-cured tobacco in the last 10 years were analyzed statistically.The results showed that the number of tobacco farmers in Shashi Town showed a rapid decline trend from 2012 to 2018,while the average age continuously increased,and the average planting scale rose in a wave like way.From 2019 to 2021,the decline rate of the number of tobacco farmers slowed down,and the average planting scale continuously increased,while the aging of tobacco farmers accelerated.Meantime,the birth years of tobacco farmers were further concentrated in the 1960s,and they were mainly at the age of 50-59.The tobacco industry in Shashi Town of Liuyang City is facing the crisis of aging tobacco farmers and no successor of flue-cured tobacco planting,and it is predicted that the next 5-10 years will continue the change trend from 2019 to 2021.
基金National Key research and Development Program,No.2022YFE0131600National Natural Science Foundation of China,No.82160500+3 种基金Special Project of Central Government Guiding Local Science and Technology Development,No.ZY20198011Guangxi Science and Technology Base and Talent Project,No.GuikeAA21220002Natural Science Foundation of Guangxi,No.2022GXNSFAA035642The Liuzhou Science and Technology Plan Project,No.2021CB0101.
文摘BACKGROUND Nonalcoholic fatty liver disease(NAFLD)has become the leading cause of cirrhosis and other chronic liver diseases(COCLDs).AIM To conduct a comprehensive and comparable updated analysis of the global,regional,and national burden of COCLDs due to NAFLD in 204 countries and territories from 1990 and 2019 by age,sex,and sociodemographic index.METHODS Data on COCLDs due to NAFLD were collected from the Global Burden of Diseases,Injuries,and Risk Factors Study 2019.Numbers and age-standardized prevalence,death,and disability-adjusted life years(DALYs)were estimated through a systematic analysis of modelled data from the Global Burden of Diseases,Injuries,and Risk Factors Study 2019.The estimated annual percentage change was used to determine the burden trend.RESULTS In 2019,the global age-standardized prevalence rate of COCLDs due to NAFLD was 15022.90 per 100000 population[95%uncertainty interval(UI):13493.19-16764.24],which increased by 24.51%(22.63%to 26.08%)from 1990,with an estimated annual percentage change of 0.78(95%confidence interval:0.74-0.82).In the same year,however,the age-standardized death rate and age-standardized DALYs per 100000 population were 1.66(95%UI:1.20-2.17)and 43.69(95%UI:31.28-58.38),respectively.North Africa and the Middle East had the highest prevalence rates of COCLDs due to NAFLD.The death rate increased with age up to the 95+age group for both sexes.Males had higher numbers of prevalence,death rate,and DALYs than females across all age groups before the 65-69 age group.The sociodemographic index was negatively correlated with the age-standardized DALYs.CONCLUSION Globally,the age-standardized prevalence rate has increased during the past three decades.However,the agestandardized death rate and age-standardized DALYs decreased.There is geographical variation in the burden of COCLDs due to NAFLD.It is strongly recommended to improve the data quality of COCLDs due to NAFLD across all countries and regions to facilitate better monitoring of the burden of COCLDs due to NAFLD.
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.
文摘At first, the concept of bridge reliability is given, followed with its mathematic model. Then, based on the analysis about the mechanism of the damage and repair of bridges, and the state diversion of bridge network, the state diversion process is proved to be birth-and-death process. In the end, the state diversion balance equation of bridge network is built, and the evaluation model of wartime bridge reliability is got. The model is used in a certain example, and it is proved to be precise and credible.
基金The Fundamental Research Funds for the Central Universities,CHD (300102129202)the NSF (11701041) of China+1 种基金the Natural Science Basic Research Plan (2018JM1011) in Shaanxi Province of ChinaScientific Innovation Practice Project (300103002110) of Postgraduates of Chang’an University
文摘In this paper, we propose an SIRS epidemic model with pulse vaccination, birth pulse and Logistic death rate. By using the stroboscopic map of a discrete dynamical system, the disease-free periodic solution (DFPS for short) of the model under pulse vaccination and birth pulse is obtained. Based on the Floquet theory and comparison theorem of impulsive differential equations, the global asymptotic stability of the DFPS is given, and sufficient conditions for the permanence of the model are obtained. In addition, numerical simulations are done to confirm our theoretical results.
文摘It has been hypothesized that during the last several decades human sperm count has declined because of prenatal exposure to environmental chemicals. We examined the relation between semen quality and birth year among 8608 men born from 1922 to 1971 and who from 1968 to 1992 consulted 4 Danish medical centers because of barren marriage. Data were obtained from medical records and by a postal questionnaire to a subset of the population. The sperm concentration was significantly declining with increasing year of birth in 2 of the 4 centers, but this association disappeared when confounders were adjusted for. Within the subset of men born during 1955~1970 comprising 36% of the entire population we revealed a decrease of the average sperm concentration by 1.6 million /ml (95% CI:0.7~2.5) per one advancing year of birth.This finding was consistent across all the 4 centers and robust to adjustment for effects of calendar period, season and duration of sexual abstinence. Effects of age were accounted for by restriction of the sample to men between 20 and 45 years. The findings are compatible with environmental impact in the prenatal period after 1955 but are far from unequivocal evidence that the sperm count in the general male Danish population has changed during the past decades.
基金Project supported by the National Natural Science Foundation,China (Grant No.10904033)the Natural Science Foundation of Hubei Province,China (Grant No.2009CDA145)+1 种基金the Science Foundation of the Educational Commission of Hubei Province,China (Grant No.D20092204)the Postgraduate Programme of Hubei Normal University of China (Grant No.2007D20)
文摘In this paper, we investigate the dynamical behaviour of entanglement in terms of concurrence in a bipartite system subjected to an external magnetic field under the action of dissipative environments in the extended Werner-like initial state. The interesting phenomenon of entanglement sudden death as well as sudden birth appears during the evolution process. We analyse in detail the effect of the purity of the initial entangled state of two qubits via Heisenberg XY interaction on the apparition time of entanglement sudden death and entanglement sudden birth. Furthermore, the conditions on the conversion of entanglement sudden death and entanglement sudden birth can be generalized when the initial entangled state is not pure. In particular, a critical purity of the initial mixed entangled state exists, above which entanglement sudden birth vanishes while entanglement sudden death appears. It is also noticed that stable entanglement, which is independent of different initial states of the qubits (pure or mixed state), occurs even in the presence of decoherence. These results arising from the combination of the extended Werner-like initial state and dissipative environments suggest an approach to control and enhance the entanglement even after purity induced sudden birth, death and revival.
文摘In recent years some interrelationships between time of birth and longevity were published. Concomitant publications appeared demonstrating links between Space Weather and the timing of medical events;in part of both these studies it was shown that Space Weather indices are stronger connected with the time of conception as with the birth time. The aim of these study was to consider birth and conception month of patients suffering from a number of “big killer” pathologies, affecting human longevity and comparing with published data on centenarians—100 - 112 years old persons in the USA. Patients and Methods: We included monthly births distribution of our four papers including patients with Acute Myocardial Infarction undergoing Percutaneous Coronary Intervention (PCI)—n-3765, and admitted in another tertiary medical facility for AMI—n-22,047, and, also patients suffering Rapid—n-1239 and Sudden Cardiac Death—n-327 and, also, patients with oncologic malignancies—n-44587. At all in this group 71,965 patients were included. Their birth and conception months were compared with analogical data of 1574 people of 100 - 112 years old using data of L.A. and N.S. Gavrilov for USA centenarians. Results: The birth months of the cardiovascular and oncology patients were maximal in January, March and April (above 10% at each of these months);their conception was maximal in April, June and July. The monthly distribution of conception and birth of the studied population is presented in Tables 1-3. The maximal birth months of the centenarians were November, September, and October;the maximal conception months were December, January, and February. Conclusion: People suffering Myocardial Infarction, Sudden Cardiac Death and Oncologic Malignancies are in higher numbers born in the first four months of the year and conception in April, June and July. The maximal birth months of the very old people were November, September and October and conception were December, January and February.
基金supported by National Natural Science Foundation of China under Grant Nos. 10775104 and 10305009
文摘We propose a monomer birth-death model with random removals, in which an aggregate of size k can produce a new monomer at a time-dependent rate I(t)k or lose one monomer at a rate J(t)k, and with a probability P(t) an aggregate of any size is randomly removed. We then anedytically investigate the kinetic evolution of the model by means of the rate equation. The results show that the scaling behavior of the aggregate size distribution is dependent crucially on the net birth rate I(t) - J(t) as well as the birth rate I(t). The aggregate size distribution can approach a standard or modified scaling form in some cases, but it may take a scale-free form in other cases. Moreover, the species can survive finally only if either I(t) - J(t) ≥ P(t) or [J(t) + P(t) - I(t)]t ≈ 0 at t ≥ 1; otherwise, it will become extinct.
文摘A new stochastic epidemic model, that is, a general continuous time birth and death chain model, is formulated based on a deterministic model including vaccination. We use continuous time Markov chain to construct the birth and death process. Through the Kolmogorov forward equation and the theory of moment generating function, the corresponding population expectations are studied. The theoretical result of the stochastic model and deterministic version is also given. Finally, numerical simulations are carried out to substantiate the theoretical results of random walk.
基金Supported by the Fundamental Research Funds for the Central Universities(JBK120405)
文摘formula of simulation proccss by In this paper, we employ monmnt generating function to obtain some exact transition probability of inlmigration-birth-death(IBD) model and discuss the of sample path and statistical inference with complete observations of the IBD the exact transition density formula.