Birth Pulse Research Articles

Nonsynchronous bifurcation of SIRS epidemic model with birth pulse and pulse vaccination

In this paper, we construct an SIRS epidemic model with birth pulse and pulse vaccination at the different fixed moment. The stability of the infection-free periodic solution is obtained by using the Poincare map. The existence of nontrivial periodic solution bifurcated from the infection-free periodic solution is discussed by means of the bifurcation theory. It is shown that once a threshold is reached, a nontrivial periodic solution emerges via a supercritical bifurcation. Furthermore, some numerical simulations are given, which are in good accordance with the theoretical results.

Chaos in a single-species discrete population model with stage structure and birth pulses

This paper gives an analytical proof of the existence of chaotic dynamics for a single-species discrete population model with stage structure and birth pulses. The approach is based on a general existence criterion for chaotic dynamics of n-dimensional maps and inequality techniques. An example is given to illustrate the effectiveness of the result.

The effect of seasonal birth pulses on pathogen persistence in wild mammal populations.

The notion of a critical community size (CCS), or population size that is likely to result in long-term persistence of a communicable disease, has been developed based on the empirical observations of acute immunizing infections in human populations, and extended for use in wildlife populations. Seasonal birth pulses are frequently observed in wildlife and are expected to impact infection dynamics, yet their effect on pathogen persistence and CCS have not been considered. To investigate this issue theoretically, we use stochastic epidemiological models to ask how host life-history traits and infection parameters interact to determine pathogen persistence within a closed population. We fit seasonal birth pulse models to data from diverse mammalian species in order to identify realistic parameter ranges. When varying the synchrony of the birth pulse with all other parameters being constant, our model predicted that the CCS can vary by more than two orders of magnitude. Tighter birth pulses tended to drive pathogen extinction by creating large amplitude oscillations in prevalence, especially with high demographic turnover and short infectious periods. Parameters affecting the relative timing of the epidemic and birth pulse peaks determined the intensity and direction of the effect of pre-existing immunity in the population on the pathogen's ability to persist beyond the initial epidemic following its introduction.

Dynamic analysis of a stage-structured predator–prey system with disturbed time delay and birth pulse

In this paper, a stage-structured predator–prey system with birth pulse and disturbed time delay is investigated. The conditions of the prey-extinction periodic solution of the system which are globally attractive have been obtained. Furthermore, the sufficient conditions for the permanence of the system are established. Finally, numerical analysis is given to confirm the theoretical results.

Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics

More than a century of ecological studies have demonstrated the importance of demography in shaping spatial and temporal variation in population dynamics. Surprisingly, the impact of seasonal recruitment on infectious disease systems has received much less attention. Here, we present data encompassing 78 years of monthly natality in the USA, and reveal pronounced seasonality in birth rates, with geographical and temporal variation in both the peak birth timing and amplitude. The timing of annual birth pulses followed a latitudinal gradient, with northern states exhibiting spring/summer peaks and southern states exhibiting autumn peaks, a pattern we also observed throughout the Northern Hemisphere. Additionally, the amplitude of United States birth seasonality was more than twofold greater in southern states versus those in the north. Next, we examined the dynamical impact of birth seasonality on childhood disease incidence, using a mechanistic model of measles. Birth seasonality was found to have the potential to alter the magnitude and periodicity of epidemics, with the effect dependent on both birth peak timing and amplitude. In a simulation study, we fitted an susceptible-exposed-infected-recovered model to simulated data, and demonstrated that ignoring birth seasonality can bias the estimation of critical epidemiological parameters. Finally, we carried out statistical inference using historical measles incidence data from New York City. Our analyses did not identify the predicted systematic biases in parameter estimates. This may be owing to the well-known frequency-locking between measles epidemics and seasonal transmission rates, or may arise from substantial uncertainty in multiple model parameters and estimation stochasticity.

Time Delayed Stage-Structured Predator-Prey Model with Birth Pulse and Pest Control Tactics

Normally, chemical pesticides kill not only pests but also their natural enemies. In order to better control the pests, two-time delayed stage-structured predator-prey models with birth pulse and pest control tactics are proposed and analyzed by using impulsive differential equations in present work. The stability threshold conditions for the mature prey-eradication periodic solutions of two models are derived, respectively. The effects of key parameters including killing efficiency rate, pulse period, the maximum birth effort per unit of time of natural enemy, and maturation time of prey on the threshold values are discussed in more detail. By comparing the two threshold values of mature prey-extinction, we provide the fact that the second control tactic is more effective than the first control method.

Periodic solutions of an SIS epidemic model with fixed-time birth pulses and state feedback pulse treatments

Fixed-time pulse and state pulse, which were discussed separately in previous works, are introduced in a susceptible-infected-susceptible (SIS) epidemic model in this paper. Periodic solutions of the SIS epidemic model with fixed-time birth pulses and state feedback pulse treatments are discussed by means of both theoretical and numerical ways. The conditions for the existence of epidemic period-(1, 1), period-(2, 1), and period-(3, 2) solution are investigated.

A Randomized Controlled Trial of Extra-amniotic Saline Infusion vs Intracervical Dinoprostone Gel for Induction of Labor

ABSTRACT Background Success of induction depends largely on cervical ripening and increases the likelihood of vaginal delivery. This study compared the outcomes for induction of labor using extra-amniotic saline infusion (EASI) vs intracervical dinoprostone gel. Objective: Primary: To compare improvement between pre- and post-induction Bishop’s scores in both the groups. Secondary: To compare induction to delivery interval, mode of delivery, and neonatal outcome in both the groups. Materials and methods A randomized controlled trial of 1 year was conducted in the Department of Obstetrics and Gynaecology, Karnataka Lingayat Education University Dr Prabhakar Kore Hospital and Medical Research Centre, Belagavi, Karnataka, India, on 82 pregnant women from January 2014 to December 2014. The selected women were divided into two groups of 41 each as group I (induced with dinoprostone) and group II (induced with EASI using Foley’s catheter). Results Significantly higher number of women had postinduction Bishop’s scores between 9 and 12 in the dinoprostone group (70.73%; p < 0.001). The mean Bishop’s scores were significantly high in the dinoprostone gel (9.27 ± 3.07) vs EASI (8.22 ± 2.34; p = 0.086). Cervical ripening based on cut-off score of ≥6 was noted in a significantly higher number of women (92.68%) in EASI (p = 0.241). The mean time for cervical ripening was significantly high in dinoprostone gel group compared with EASI (15.44 ± 8.41 vs 3.88 ± 3.67; p < 0.001), but mean induction to delivery time was comparable (p = 0.086). Significantly higher numbers of vaginal deliveries were noted in dinoprostone group (91.43%; p = 0.001). The neonatal outcomes, i.e., birth weight, mean birth weight, appearance, pulse, grimace, activity, and respiration score at 1 and 5 minutes, and neonatal intensive care unit admission, were comparable (p = 0.570). Conclusion Dinoprostone gel and EASI using Foley’s catheter appear to be effective methods for cervical ripening and labor induction, but dinoprostone gel yielded significantly higher rate of vaginal delivery. How to cite this article Rodrigues SV, Swamy MK, Jadhav N. A Randomized Controlled Trial of Extra-amniotic Saline Infusion vs Intracervical Dinoprostone Gel for Induction of Labor. Int J Gynecol Endsc 2017;1(1):11-17

Global dynamics of an SIRS epidemic model with saturation incidence

In this paper, the dynamical behavior of an SIRS epidemic model with birth pulse, pulse vaccination, and saturation incidence is studied. By using a discrete map, the existence and stability of the infection-free periodic solution and the endemic periodic solution are investigated. The conditions required for the existence of supercritical bifurcation are derived. A threshold for a disease to be extinct or endemic is established. The Poincaré map and center manifold theorem are used to discuss flip bifurcation of the endemic periodic solution. Moreover, numerical simulations for bifurcation diagrams, phase portraits and periodic solutions, which are illustrated with an example, are in good agreement with the theoretical analysis.

A delayed Lotka–Volterra model with birth pulse and impulsive effect at different moment on the prey

In this paper, we consider a Lotka–Volterra model with birth pulse and impulsive catching or poisoning for the prey at different moment and stage structure on the predator. We prove that all solutions of the system are uniformly ultimately bounded. Sufficient conditions of the global attractivity of predator-extinction periodic solution and the permanence of the system are obtained. These results show that impulsive effects on the prey play an important role for the permanence of the system. In this paper, the main feature is to introduce birth pulse and impulse catching into Lotka–Volterra model and to give pest management strategies.

Contraception can Lead to Trophic Asynchrony between Birth Pulse and Resources

Abiotic inputs such as photoperiod and temperature can regulate reproductive cyclicity in many species. When humans perturb this process by intervening in reproductive cycles, the ecological consequences may be profound. Trophic mismatches between birth pulse and resources in wildlife species may cascade toward decreased survival and threaten the viability of small populations. We followed feral horses (Equus caballus) in three populations for a longitudinal study of the transient immunocontraceptive porcine zona pellucida (PZP), and found that repeated vaccinations extended the duration of infertility far beyond the targeted period. After the targeted years of infertility, the probability of parturition from post-treated females was 25.6% compared to 64.1% for untreated females, when the data were constrained only to females that had demonstrated fertility prior to the study. Estimated time to parturition increased 411.3 days per year of consecutive historical treatment. Births from untreated females in these temperate latitude populations were observed to peak in the middle of May, indicating peak conception occurred around the previous summer solstice. When the post-treated females did conceive and give birth, parturition was an estimated 31.5 days later than births from untreated females, resulting in asynchrony with peak forage availability. The latest neonate born to a post-treated female arrived 7.5 months after the peak in births from untreated females, indicating conception occurred within 24–31 days of the winter solstice. These results demonstrate surprising physiological plasticity for temperate latitude horses, and indicate that while photoperiod and temperature are powerful inputs driving the biological rhythms of conception and birth in horses, these inputs may not limit their ability to conceive under perturbed conditions. The protracted infertility observed in PZP-treated horses may be of benefit for managing overabundant wildlife, but also suggests caution for use in small refugia or rare species.

The dynamics of a delayed pest management SEI system with impulsive harvesting at different moments

According to biological strategy for pest control, we consider a delayed pest management SEI model with birth pulse and impulsive harvesting at different moments. We prove that all solutions of the system are uniformly ultimately bounded and get the conditions of the globally attractive infection-free boundary periodic solution of the system. Further, we obtain sufficient condition with time delay for the permanence of the system. Our results give some reasonable suggestions for pest

An epidemic model with pulses for pest management

Using parasitic wasps that deliver lethal viruses to crop pests is a new way to protect crops. In this paper, we propose and analyze an epidemic model with birth pulse and pulse infection by virus, which periodic birth pulse and pulse infection occur at different fixed time. An exact cycle of the system and the threshold conditions for its stability are obtained. Some numerical simulations are given. Moreover, the sufficient conditions of global stability of semi-trivial periodic solutions are investigated. Our proposed strategy of delivering deadly viruses is effective and adequate from the environmental point of view.

Reproductive success of female leopards Panthera pardus: the importance of top‐down processes

Abstract Long‐term studies on large felids are rare and yet they yield data essential to understanding the behaviour of species and the factors that facilitate their conservation. We used the most extensive data set so far compiled on leopards Panthera pardus to establish baseline reproductive parameters for females and to determine the demographic and environmental factors that affect their lifetime reproductive success. We used comprehensive sightings reports and photographs from ecotourism lodges in the Sabi Sand Game Reserve, South Africa, to reconstruct life histories for 44 female leopards that gave birth to 172 litters over a 32‐year period. Leopards appeared to exhibit a birth pulse; most litters were born in the wet season, particularly in December. Mean age at first parturition (n = 26, mean ± standard error = 46 ± 2 months, range = 33–62) was older than previously recorded, possibly due to elevated intraspecific competition. Average litter size was 1.9 ± 0.1 (n = 140, range = 1–3) and declined with maternal age. Age of litters at independence (n = 52, 19 ± 1 months, range = 9–31) was inversely related to prey abundance but did not affect the likelihood of recruitment of offspring. Interbirth intervals differed following successful litters (in which at least one cub survived to independence; n = 55, 25 ± 1 months, range = 14–39) and unsuccessful litters (n = 46, 11 ± 1 months, range = 4–36), as did the time taken to replace litters. Variation in lifetime reproductive success was influenced mainly by differences in cub survival, which was related to maternal age and vulnerability to infanticide. Cub survival (37%) declined as females got older, perhaps because mothers relinquished portions of their home ranges to philopatric daughters. Male leopards were responsible for many (40%) cub deaths and females appeared to adopt severalstrategies to counter the risk of infanticide, including paternity confusion and displaying a period of reduced fertility immediately after a resident male was replaced. Our results suggest that the reproductive success of female leopards is regulated primarily by top‐down processes. This should be taken into account in management decisions, particularly when managers are considering the implementation of invasive activities such as legal trophy hunting.

Birth timing for mountain lions (Puma concolor); testing the prey availability hypothesis.

We investigated potential advantages in birth timing for mountain lion (Puma concolor) cubs. We examined cub body mass, survival, and age of natal dispersal in relation to specific timing of birth. We also investigated the role of maternal age relative to timing of births. We captured mountain lion cubs while in the natal den to determine birth date, which allowed for precise estimates of the population birth pulse and age of natal dispersal. A birth pulse occurred during June–August. Body mass of cubs was related to litter size and timing of birth; heaviest cubs occurred in litters of 2, and those born after 1 July. Cubs born within pulse months exhibited similar survival to those born out of the pulse. We found that cubs born April–June dispersed at younger ages than those born after 1 July. There was less variation in birth timing for 1st litters of females than older females. We hypothesize that cubs born after the peak in births of neonate prey are advantaged by the abundance of vulnerable prey and those cubs and mothers realize an evolutionary advantage.

Spreading Speed, Traveling Waves, and Minimal Domain Size in Impulsive Reaction–Diffusion Models

How growth, mortality, and dispersal in a species affect the species' spread and persistence constitutes a central problem in spatial ecology. We propose impulsive reaction-diffusion equation models for species with distinct reproductive and dispersal stages. These models can describe a seasonal birth pulse plus nonlinear mortality and dispersal throughout the year. Alternatively, they can describe seasonal harvesting, plus nonlinear birth and mortality as well as dispersal throughout the year. The population dynamics in the seasonal pulse is described by a discrete map that gives the density of the population at the end of a pulse as a possibly nonmonotone function of the density of the population at the beginning of the pulse. The dynamics in the dispersal stage is governed by a nonlinear reaction-diffusion equation in a bounded or unbounded domain. We develop a spatially explicit theoretical framework that links species vital rates (mortality or fecundity) and dispersal characteristics with species' spreading speeds, traveling wave speeds, as well as minimal domain size for species persistence. We provide an explicit formula for the spreading speed in terms of model parameters, and show that the spreading speed can be characterized as the slowest speed of a class of traveling wave solutions. We also give an explicit formula for the minimal domain size using model parameters. Our results show how the diffusion coefficient, and the combination of discrete- and continuous-time growth and mortality determine the spread and persistence dynamics of the population in a wide variety of ecological scenarios. Numerical simulations are presented to demonstrate the theoretical results.

Dynamics of the genic mutational rate on a population system with birth pulse and impulsive input toxins in polluted environment

In this paper, we consider the genic mutation on an impulsive population system in polluted environment. All solutions of the investigated system are proved to be uniformly bounded. Using mathematical analysis methods, the conditions of the globally asymptotically stable population-extinction solution of the investigated system are obtained. The permanent condition of the investigated system is also obtained. Finally, numerical analysis is carried out illustrate our results. Our results provide reliable tactic basis for the practical biological resource management in polluted environment.

The genic mutation on dynamics of a predator–prey system with impulsive effect

In this work, we consider a genic mutational predator–prey system with birth pulse and impulsive cutting on prey population at different moments. All the solutions of the investigated system are proved to be uniformly ultimately bounded. The conditions of the globally asymptotically stable predator-extinction boundary periodic solution of the investigated system are obtained. The permanent conditions of the investigated system are also obtained. Finally, numerical simulations are inserted to illustrate the results. Our results present that the genic mutational rate plays an important role on the permanence of the investigated system. Our results also provide reliable tactic basis for the practical biological economics management.

Host and viral ecology determine bat rabies seasonality and maintenance

Rabies is an acute viral infection that is typically fatal. Most rabies modeling has focused on disease dynamics and control within terrestrial mammals (e.g., raccoons and foxes). As such, rabies in bats has been largely neglected until recently. Because bats have been implicated as natural reservoirs for several emerging zoonotic viruses, including SARS-like corona viruses, henipaviruses, and lyssaviruses, understanding how pathogens are maintained within a population becomes vital. Unfortunately, little is known about maintenance mechanisms for any pathogen in bat populations. We present a mathematical model parameterized with unique data from an extensive study of rabies in a Colorado population of big brown bats (Eptesicus fuscus) to elucidate general maintenance mechanisms. We propose that life history patterns of many species of temperate-zone bats, coupled with sufficiently long incubation periods, allows for rabies virus maintenance. Seasonal variability in bat mortality rates, specifically low mortality during hibernation, allows long-term bat population viability. Within viable bat populations, sufficiently long incubation periods allow enough infected individuals to enter hibernation and survive until the following year, and hence avoid an epizootic fadeout of rabies virus. We hypothesize that the slowing effects of hibernation on metabolic and viral activity maintains infected individuals and their pathogens until susceptibles from the annual birth pulse become infected and continue the cycle. This research provides a context to explore similar host ecology and viral dynamics that may explain seasonal patterns and maintenance of other bat-borne diseases.

Analysis of a stage-structured predator–prey system with birth pulse and impulsive harvesting at different moments

In this work, we consider a stage-structured predator–prey system with birth pulse and impulsive harvesting at different moments. Firstly, we prove that all solutions of the investigated system are uniformly ultimately bounded. Secondly, the conditions of the globally asymptotically stable prey-extinction boundary periodic solution of the investigated system are obtained. Thirdly, the permanence of the investigated system is also obtained. Finally, numerical analysis is inserted to illustrate the results. Our results provide reliable tactic basis for the practical biological economics management.