Cladoceran birth and death rates estimates

I. Birth and death rates of natural cladoceran populations cannot be measured directly. Estimates of these population parameters must be calculated using methods that make assumptions about the form of population growth. These methods generally assume that the population has a stable age distribution. 2. To assess the effect of variable age distributions, we tested six egg ratio methods for estimating birth and death rates with data from thirty-seven laboratory populations of Daphnia pulicaria. The populations were grown under constant conditions, but the initial age distributions and egg ratios of the populations varied. Actual death rates were virtually zero, so the difference between the estimated and actual death rates measured the error in both birth and death rate estimates. 3. The results demonstrate that unstable population structures may produce large errors in the birth and death rates estimated by any of these methods. Among the methods tested, Taylor and Slatkin's formula and Paloheimo's formula were most reliable for the experimental data. 4. Further analyses of three of the methods were made using computer simulations of growth of age-structured populations with initially unstable age distributions. These analyses show that the time interval between sampling strongly influences the reliability of birth and death rate estimates. At a sampling interval of 2.5 days (equal to the duration of the egg stage), Paloheimo's formula was most accurate. At longer intervals (7.5–10 days), Taylor and Slatkin's formula which includes information on population structure was most accurate

The Cosmic Stellar Birth and Death Rates

The cosmic stellar birth rate can be measured by standard astronomical techniques. It can also be probed via the cosmic stellar death rate, though until recently, this was much less precise. However, recent results based on measured supernova rates, and importantly, also on the attendant diffuse fluxes of neutrinos and gamma rays, have become competitive, and a concordant history of stellar birth and death is emerging. The neutrino flux from all past core-collapse supernovae, while faint, is realistically within reach of detection in Super-Kamiokande, and a useful limit has already been set. I will discuss predictions for this flux, the prospects for neutrino detection, the implications for understanding core-collapse supernovae, and a new limit on the contribution of type-Ia supernovae to the diffuse gamma-ray background.Comment: Accepted for publication in New Astronomy Reviews (invited talk at "Astronomy with Radioactivities V", Clemson Univ., Sept. 2005). 9 pages, 5 figure

Death rates from malaria epidemics, Burundi and Ethiopia.

Death rates exceeded emergency thresholds at 4 sites during epidemics of Plasmodium falciparum malaria in Burundi (2000-2001) and in Ethiopia (2003-2004). Deaths likely from malaria ranged from 1,000 to 8,900, depending on site, and accounted for 52% to 78% of total deaths. Earlier detection of malaria and better case management are needed

Health and Wellness: Black Facts

Every year approximately 85,000 African American deaths are attributed to the Black – White mortality gap. Racial disparities in health in the United States are substantial. Today, death rates for African Americans remain 40% higher than for whites. They were similar in 1960. The overall death rate for Blacks today is comparable to the rate for Whites thirty years ago, with about 100,000Blacks dying each year that would not die if the death rates were equivalent

Leading Causes of Death in Vietnam

Vietnam is currently facing a public health crisis. Rates of chronic and preventable diseases are climbing, in addition to mortality rates from these diseases. If nothing is done to halt these rising rates, the health of the Vietnamese people will only continue to decline. Although there may be many factors contributing to these high death rates due to chronic diseases, risky health behaviors, such as smoking, and the state of the healthcare system can be considered two main contributors to the leading causes of death in Vietnam. The high smoking rates and high costs of healthcare are hindering the health of Vietnam, and may be related to the top causes of death, including stroke, ischemic heart disease, chronic obstructive pulmonary disease (COPD), and lower respiratory infections (World Health Organization and UN partners, 2015). Implementing government programs, including smoking cessation, smoking education, tobacco taxes, healthcare education, and continued work toward universal healthcare coverage, will hopefully help decrease the rising rates of chronic diseases and the high mortality rates they cause.https://jdc.jefferson.edu/cwicposters/1033/thumbnail.jp

On a bilateral birth-death process with alternating rates

We consider a bilateral birth-death process characterized by a constant transition rate $\lambda$ from even states and a possibly different transition rate $\mu$ from odd states. We determine the probability generating functions of the even and odd states, the transition probabilities, mean and variance of the process for arbitrary initial state. Some features of the birth-death process confined to the non-negative integers by a reflecting boundary in the zero-state are also analyzed. In particular, making use of a Laplace transform approach we obtain a series form of the transition probability from state 1 to the zero-state.Comment: 13 pages, 3 figure

Intertwining of birth-and-death processes

It has been known for a long time that for birth-and-death processes started in zero the first passage time of a given level is distributed as a sum of independent exponentially distributed random variables, the parameters of which are the negatives of the eigenvalues of the stopped process. Recently, Diaconis and Miclo have given a probabilistic proof of this fact by constructing a coupling between a general birth-and-death process and a process whose birth rates are the negatives of the eigenvalues, ordered from high to low, and whose death rates are zero, in such a way that the latter process is always ahead of the former, and both arrive at the same time at the given level. In this note, we extend their methods by constructing a third process, whose birth rates are the negatives of the eigenvalues ordered from low to high and whose death rates are zero, which always lags behind the original process and also arrives at the same time.Comment: 12 pages. 1 figure. Some typoes corrected and minor change

Sampling through time and phylodynamic inference with coalescent and birth-death models

Many population genetic models have been developed for the purpose of inferring population size and growth rates from random samples of genetic data. We examine two popular approaches to this problem, the coalescent and the birth-death-sampling model, in the context of estimating population size and birth rates in a population growing exponentially according to the birth-death branching process. For sequences sampled at a single time, we found the coalescent and the birth-death-sampling model gave virtually indistinguishable results in terms of the growth rates and fraction of the population sampled, even when sampling from a small population. For sequences sampled at multiple time points, we find that the birth-death model estimators are subject to large bias if the sampling process is misspecified. Since birth-death-sampling models incorporate a model of the sampling process, we show how much of the statistical power of birth-death-sampling models arises from the sequence of sample times and not from the genealogical tree. This motivates the development of a new coalescent estimator, which is augmented with a model of the known sampling process and is potentially more precise than the coalescent that does not use sample time information.Comment: Submitte

Competetive exclusion in Cladocera through elevated mortality of adults

The population dynamics of two cladocerans, Ceriodaphnia pulchella and Diaphanosoma brachyurum competing under laboratory conditions in lake water was analysed using crosscorrelations. Both mixed and isolated populations of the two cladocerans showed delayed density dependence in the death rates of juveniles and adults as well as in fecundity rate. The regressions for each of the three rates on total density of competitors were compared between the two species. There were no significant differences in the slopes of regressions for fecundity rates and the death rates of juveniles. However, in the inferior competitor (Diaphanosoma) which went extinct in all treatments, the death rate of adults increased with total density much more quickly than in the superior competitor (Ceriodaphnia). The intraspecific comparisons indicated that while Ceriodaphnia adults survived better than juveniles under conditions of crowding, in Diaphanosoma, juveniles were better survivors than adults. These data suggest that the contention of higher vulnerability of cladoceran juveniles than adults to starvation and crowding may prove to be not a universal phenomenon

On associated polynomials and decay rates for birth-death processes

We consider sequences of orthogonal polynomials and pursue the question of how (partial) knowledge of the orthogonalizing measure for the {\it associated polynomials} can lead to information about the orthogonalizing measure for the original polynomials. In particular, we relate the supports of the two measures, and their moments. As an application we analyse the relation between two decay rates connected with a birth-death process. \u