A dispersal-aggregation model for mountain pine beetle in lodgepole pine stands

Summary In this paper a dispersal-attack theory for bark beetle attacking trees is developed from a set of simple assumptions, and the resulting theoretical model is fit to data from four epidemic studies. Implications of the theory are discussed in relation to the dynamics of lodgepole pine-mountain pine beetle interactions. Scientific paper #4632, Project #102, College of Agriculture Research Center, Washington State university, Pullman, Washington. The work reported herein is the result of cooperation between scientists at Washington State University, the University of Idaho, and the U.S. Forest Service, and is supported by the National Science Foundation (Grant No. GB-341728), through contract SC 0024 with the University of California (Berkeley). The opinions expressed herein are not necessarily those of California or NSF.     

Concept,measurement, and data in migration analysis

Two methods of computing migration rates-one relating moves to population at risk in place of origin and the other using as a denominator the cross-product of population in places of origin and destination-are discussed. It is concluded that the second assumes implicitly that moves originate and terminate as a random population variable.Some difficulties with this particular model are pointed out and the author suggests that other analytical approaches to migration data be sought and in this connection refers to the literature on the mathematical theory of epidemics.     

Two fish species competition model with nonlinear interactions and equilibrium catches

Summary Two species competition model is built up by assuming the hypothetical second order interactions in order to consider effects of exploitation on two competing fish species with non-linear interactions. Most important characteristic of this model, compared withLotka-Volterra type linear competition model, is that this model can possess multiple stable equilibrium points. Therefore there is a possibility that two species keeping the equilibrium state at one stable equilibrium point will be attracted to the other stable equilibrium point after a heavy perturbation. In this model reversible change of the fishing pressure does not always results in that of the equilibrium catch. In this sence MSY concept for single species can not be extended to this model. If there are multiple stable equilibrium points, the change of the dominant fish species, catastrophic and irreversible change of each equilibrium catch may be observed when the perturbation by the exploitation is added. This phenomenon immediately reminds us of the change of the dominant fish species between Japanese common mackerel and Pacific saury in the northwest Pacific Ocean. In case of the management of two competing fish species with nonlinear interactions, the consideration on the balance between the fishing pressure for each species may be as important as the decision on the catch limit for each species. MSY level for each species based on the single-species theory could be quite erroneous.     

Probabilistic population projections for countries with generalized HIV/AIDS epidemics

In 2015, the United Nations (UN) issued probabilistic population projections for all countries up to 2100, by simulating future levels of total fertility and life expectancy and combining the results using a standard cohort component projection method. For the 40 countries with generalized HIV/AIDS epidemics, the mortality projections used the Spectrum/Estimation and Projection Package (EPP) model, a complex, multistate model designed for short-term projections of policy-relevant quantities for the epidemic. We propose a simpler approach that is more compatible with existing UN projection methods for other countries. Changes in life expectancy are projected probabilistically using a simple time series regression and then converted to age- and sex-specific mortality rates using model life tables designed for countries with HIV/AIDS epidemics. These are then input to the cohort component method, as for other countries. The method performed well in an out-of-sample cross-validation experiment. It gives similar short-run projections to Spectrum/EPP, while being simpler and avoiding multistate modelling.     

Simple mathematical models to describe the rate of mating in insect populations

Summary Simple models are constructed to describe the rate of mating in insect populations. The models are based on the assumption of random mate-searching in a closed habitat, including four parameters, i.e., population size, sex ratio, searching efficiency and male's capacity on mating frequency. The modes of effects of these parameters on the rate of mating are analyzed and some principles deduced are discussed in relation to the mating process in natural populations. This study was supported by science research fund from the Ministry of Education.     

Persistence of abnormal females that produce only female progeny with occasional recovery to normal females in Lepidoptera

In Lepidoptera, females that produce only female progeny have been found in wild populations of at least 12 species. In some species, recoveries, where abnormal females return to normal females, have been observed. A mathematical model of the population dynamics with recovery was developed to identify the conditions for realizing the persistence of abnormal females. Analysis indicated normal and abnormal females coexist and reach an equilibrium state at certain recovery rate values. The equilibrium values of normal and abnormal females were determined. When a population was in equilibrium it was shown that the ratio of normal to abnormal females and the sex ratio after reproduction are always functions of the recovery rate and the proportion of female offspring from an abnormal female to that from a normal female. Using the simulation it was found that, even when a population fluctuates under variable environmental conditions, the two ratios mentioned above reach equilibrium. Equilibrium relationships were applied to published data, and it was concluded that recovery from abnormal to normal females explains the persistence of abnormal females in some species of Lepidoptera. The model developed in this paper can also be used for analysing the persistence of abnormal females of other insect species.     

Pussy grabs back: bestialized sexual politics and intersectional failure in protest posters for the 2017 women’s march

The women’s march on Washington on January 21 2017 and its more than 600 sister marches across the world was characterized by its distinctly feline theme. Most notable were the pink pussy hats and a multitude of signs that played on the historical association between women and cats to resist the crude remarks made by US presidential nominee Donald Trump who bragged of grabbing women “by the pussy.” This article explores this feline counterframing from a vegan feminist perspective. A content analysis was performed on photographs that were published in Why I March (2017) and uploaded to the Women’s March on Washington Archives Project, the Georgia State University Women’s Marches 2017 Collection, and Instagram in Spring 2017. Results illustrate the persistent role that animality plays in feminist politics, but they also point to a critical intersectional failure exhibited by an ultimately anthropocentric collective.     

Rural electrification and fertility change

This article addresses the possible linkage between the spread of electrification in rural areas and subsequent declines in human fertility. Evidence from nine studies in six countries is reviewed and compared. The conclusion from this review is that there is, in fact, some link and that the higher the level of rural electrification the higher is contraceptive prevalence and the lower is the level of fertility. This link appears puzzling at first glance, but the article proposes a conceptual and theoretical framework for interpreting these results and fitting them into accepted theories of fertility. Finally, some important policy implications are discussed and future directions for research indicated.This paper was prepared for a workshop on The Relationship between Rural Electrification and Fertility Decline sponsored by the National Rural Electrical Cooperatives Association and the Population Issues Research Center of Pennsylvania State University. The workshop was held in Washington, D.C. on November 15, 1984. (Copies of a summary of the proceedings of the workshop can be obtained from Mr. Philip P. Costas, International Programs Division, National Rural Electrical Cooperatives Association, 1800 Massachusetts Avenue N.W., Washington, D.C. 20036, U.S.A.) The authors received helpful comments on the paper from Richard Bilsborrow, Gretchen Cornwell, Gordon DeJong, Ronald Freedman, and Ozzie Simmons as well as many other participants in the workshop.     

Native American kids: American Indian children’s well-being indicators for the nation and two states

American Indian/Alaska Native well-being, survival-based data are rare. This study explores the question of whether or not it is possible to produce such well-being information using secondary data sources. The answer is yes, with some limitations. Hence, Native American data for 10 well-being indicators nationally and for New Mexico and South Dakota, using a model like Kids Count (Annie E. Casey Foundation: 2003a, 2001 KIDS COUNT Data Book: State profiles of child well-being (Annie E. Casey Foundation, Baltimore, MD)) are reported; thereby reducing the gap in survival indicators for U.S. Indigenous children and youths. Comparisons between all children and American Indian children demonstrate that Native American children have comparatively worse well-being rates at the national level and in South Dakota, whereas New Mexico Native kids compare favorably to their non-Native peers. Policy recommendations conclude the paper. This research was funded by Casey Family Programs (Seattle, Washington) and the Annie E. Casey Foundation (Baltimore, Maryland) with partnership from the National Indian Child Welfare Association (Portland, Oregon). Charlotte Goodluck, Ph.D. collaborated with me on previous work that this study builds upon. I would also like to thank the anonymous reviewers for their comments, this paper is much improved because of their efforts. Angela A. A. Willeto is an enrolled member of the Navajo Nation.     

The structure and behavior of defoliating insect/forest systems

Summary Using four detailed and complex simulation models we derive a framework for predicting behavior of any defoliating insect/forest system. The framework uses simple and easily gathered biological information on four sets of state variables, each with a characteristic temporal scale, to predict presence, absence or form of key ecological processes acting on or between the variables. The combination of these key processes enables prediction of system equilibrium structure and this structure can be used to derive the temporal behavior of the system. Four qualitatively different classes of system behavior arise from the equilibrium structures. The framework is tested against twelve other systems and field invalidation experiments are outlined. Forest defoliator research and management implications are discussed.     

Modeling plant disease increase as a function of vector numbers: Nonpersistent viruses

Summary An understanding of most plant virus disease epidemics requires a consideration of the population dynamics of insect vectors that transmit the viruses and the relationship between vector and disease dynamics. Some simple analytical (continuous-time) models are proposed for nonpersistently transmitted viruses that center on the absolute     

Family building: A social psychological study of fertility decisions

Decision theory, coupled with a hierarchically arranged questionnaire format, is discussed as a possible approach to the prediction of birth planning decisions. The empirical success of the scheme is examined in terms of interrelating attitudes, behavioral intention, desired family size, and birth planning behavior.This project was supported by Research Grant HD-07225-01A1 from the National Institute of Child Health and Human Development Center for Population Research, by NICHD Center Grant HD-09397-01 to the Center for Studies in Demography and Ecology, University of Washington, and by the University of Washington Graduate School Research Projects Fund, from the Public Health Service Biomedical Research Support Grants, Grant #RR07096. The authors thank Dr. Barbara H. Beach for her help with the data analyses. Requests for reprints should be sent to Brenda D. Townes, Ph.D., Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington 98195.     

Cycles in the two-sex problem: an investigation of a nonlinear demographic model

"A fundamental shortcoming of classic stable population theory is its failure to handle populations differentiated by sex. The classic theory is linear while the two-sex problem is inherently nonlinear. Previous two-sex investigations have focused on equilibrium conditions rather than dynamics, and ignored competition between age groups for marriage partners. This study makes a start at analyzing dynamics and models that incorporate competition, which can play an important role in any realistic marriage model and can turn a model with a stable equilibrium sex ratio into one with a cycling equilibrium." This is a revised version of a paper originally presented at the 1990 Annual Meeting of the Population Association of America. (SUMMARY IN FRE)     

Institutional Quality and Generalized Trust: A Nonrecursive Causal Model

This paper investigates the association between institutional quality and generalized trust. Despite the importance of the topic, little quantitative empirical evidence exists to support either unidirectional or bidirectional causality for the reason that cross-sectional studies rarely model the reciprocal relationship between institutional quality and generalized trust. Using data from the World Values Survey, World Bank, and other data sources in an identified nonrecursive structural equation model, results show that generalized trust and institutional quality form a positive reciprocal relationship, where the connection is stronger from generalized trust to institutional quality. The conclusion discusses implications for theory and policy in this area.     

Has the HIV Epidemic Peaked?

This study reviews the highly diverse regional and country patterns of HIV epidemics and discusses possible causes of the geographic variation in epidemic sizes. Past trends and projections of the epidemics are presented and the peak years of epidemics are estimated. The potential future impact of new prevention technologies is briefly assessed. A final section summarizes the future impact of the epidemic on key demographic variables. The main finding of this analysis is that the HIV epidemic reached a major turning point over the past decade. The peak years of HIV incidence rates are past for all regions, and the peaks of prevalence rates are mostly in the past except in Eastern Europe, where they are expected to peak in 2008. But owing in part to the life‐prolonging effect of antiretroviral therapy and to sustained population growth, the absolute number of infected individuals is expected to keep growing slowly in sub‐Saharan Africa and to remain near current levels worldwide, thus posing a continuing challenge to public health programs. No country is expected to see a decline in its population size between 2005 and 2050 that is attributable to high mortality related to AIDS.     

Modeling household fertility decisions with generalized Poisson regression

This paper models household fertility decisions by using a generalized Poisson regression model. Since the fertility data used in the paper exhibit under-dispersion, the generalized Poisson regression model has statistical advantages over both standard Poisson and negative binomial regression models, and is suitable for analysis of count data that exhibit either over-dispersion or under-dispersion. The model is estimated by the method of maximum likelihood. Approximate tests for the dispersion and goodness-of-fit measures for comparing alternative models are discussed. Based on observations from the Panel Study of Income Dynamics of 1989 interviewing year, the empirical results support the fertility hypothesis of Becker and Lewis (1973). Received January 7, 1997 /Accepted April 3, 1997     

What is a quality of life indicator?

The concepts of indicator, social indicator, and life quality indicator are defined and exemplified. An indicator is characterized as an observable variable assumed to point to, or estimate, some other (usually unobservable) variable. It is, then, a symptom of something else. An indicator-indicated relation can be functional or it can consist in statistical correlation. It is a corrigible hypothesis, not an arbitrary definition. As such it is best justified when incorporated into a theory, e.g. a mathematical model. A social indicator is of course an indicator belonging to some sociological context. Finally, a quality of life indicator is one that allows one to estimate degrees of well-being. Some of the problems posed by this definition are discussed. The upshot of the discussion is that a better understanding and assessment of the quality of life calls for more intense theoretical and methodological work rather than an increase in the amount of social and environmental statistics. Here as elsewhere data without ideas are sterile when not misleading.     

Impact of developmental variance on behavior of models for insect populations I. Models for populations with unrestricted growth

Summary The concept of developmental variance is discussed with reference to its use in models for insect populations. When included in a model, developmental variance is typically used to describe the variation of developmental periods among individuals. However, its presence in a model can also have indirect impact on survival and fertility schedules. This impact can lead to significant changes in population growth rates and generation times. These relationships between developmental variance and population growth in models are quantified and discussed.     

Accounting for Cross-National Differences in Infant Mortality Decline (1965–1991) among less Developed Countries: Effects of Women's Status,Economic Dependency,and State Strength

The present study tests models derived from four theoretical perspectives: Modernization/free trade theory, gender inequality theory, developmental state theory, and dependency theory. It is based on a sample of 82 less developed countries for the period from 1965 to 1991. We find some support for each theoretical perspective. Foreign trade, investment, and debt dependency have adverse effects on infant mortality, mediated by variables linked to modernization/free trade theory and gender inequality theory. State strength has a beneficial direct effect on infant mortality decline. Women's education and reproductive autonomy have significant direct effects, but also play important roles as mediating variables as does rate of economic growth.