686 research outputs found
Smoking and Its Consequences in Pregnant Women in Ukraine
Smoking during pregnancy increases the risk of a number of complications of pregnancy and can have adverse effects on the child. This study provides data from Ukraine that are consistent with the international literature on the effects of smoking during pregnancy. The study of nearly 700 women in Ukraine examined the rate of smoking during pregnancy and factors related to continued smoking. It documents the outcomes of pregnancy in women who smoked prior to pregnancy, and who smoked during pregnancy compared to those who did not. It also looks at pregnancy outcomes with respect to the baby’s father smoking. Smoking during pregnancy is at low levels in Ukraine (<5% of pregnant women), but is associated with family structure, the baby’s father smoking, and the number of previous abortions. It is also associated with placental insufficiency, low birth weight, fetus hypotrophy, and hip joint dysphasia. The father’s smoking is associated with decreased fertility, late toxicosis, miscarriage threat in third trimester, small baby, and lower infant functional status. There was no evidence that information on the dangers of smoking while pregnant encouraged cessation.World Bank by the Swedish International
Development Cooperation Agency (SIDA) and the US Centers for Disease Control,
Office on Smoking and Healt
Complex population dynamics as a competition between multiple time-scale phenomena
The role of the selection pressure and mutation amplitude on the behavior of
a single-species population evolving on a two-dimensional lattice, in a
periodically changing environment, is studied both analytically and
numerically. The mean-field level of description allows to highlight the
delicate interplay between the different time-scale processes in the resulting
complex dynamics of the system. We clarify the influence of the amplitude and
period of the environmental changes on the critical value of the selection
pressure corresponding to a phase-transition "extinct-alive" of the population.
However, the intrinsic stochasticity and the dynamically-built in correlations
among the individuals, as well as the role of the mutation-induced variety in
population's evolution are not appropriately accounted for. A more refined
level of description, which is an individual-based one, has to be considered.
The inherent fluctuations do not destroy the phase transition "extinct-alive",
and the mutation amplitude is strongly influencing the value of the critical
selection pressure. The phase diagram in the plane of the population's
parameters -- selection and mutation is discussed as a function of the
environmental variation characteristics. The differences between a smooth
variation of the environment and an abrupt, catastrophic change are also
addressesd.Comment: 15 pages, 12 figures. Accepted for publication in Phys. Rev.
Ecological equivalence: a realistic assumption for niche theory as a testable alternative to neutral theory
Hubbell's 2001 neutral theory unifies biodiversity and biogeography by modelling steady-state distributions of species richness and abundances across spatio-temporal scales. Accurate predictions have issued from its core premise that all species have identical vital rates. Yet no ecologist believes that species are identical in reality. Here I explain this paradox in terms of the ecological equivalence that species must achieve at their coexistence equilibrium, defined by zero net fitness for all regardless of intrinsic differences between them. I show that the distinction of realised from intrinsic vital rates is crucial to evaluating community resilience. An analysis of competitive interactions reveals how zero-sum patterns of abundance emerge for species with contrasting life-history traits as for identical species. I develop a stochastic model to simulate community assembly from a random drift of invasions sustaining the dynamics of recruitment following deaths and extinctions. Species are allocated identical intrinsic vital rates for neutral dynamics, or random intrinsic vital rates and competitive abilities for niche dynamics either on a continuous scale or between dominant-fugitive extremes. Resulting communities have steady-state distributions of the same type for more or less extremely differentiated species as for identical species. All produce negatively skewed log-normal distributions of species abundance, zero-sum relationships of total abundance to area, and Arrhenius relationships of species to area. Intrinsically identical species nevertheless support fewer total individuals, because their densities impact as strongly on each other as on themselves. Truly neutral communities have measurably lower abundance/area and higher species/abundance ratios. Neutral scenarios can be parameterized as null hypotheses for testing competitive release, which is a sure signal of niche dynamics. Ignoring the true strength of interactions between and within species risks a substantial misrepresentation of community resilience to habitat los
Stochastic population growth in spatially heterogeneous environments
Classical ecological theory predicts that environmental stochasticity
increases extinction risk by reducing the average per-capita growth rate of
populations. To understand the interactive effects of environmental
stochasticity, spatial heterogeneity, and dispersal on population growth, we
study the following model for population abundances in patches: the
conditional law of given is such that when is small the
conditional mean of is approximately , where and are the abundance and per
capita growth rate in the -th patch respectivly, and is the
dispersal rate from the -th to the -th patch, and the conditional
covariance of and is approximately . We show for such a spatially extended population that if
is the total population abundance, then ,
the vector of patch proportions, converges in law to a random vector
as , and the stochastic growth rate equals the space-time average per-capita growth rate
\sum_i\mu_i\E[Y_\infty^i] experienced by the population minus half of the
space-time average temporal variation \E[\sum_{i,j}\sigma_{ij}Y_\infty^i
Y_\infty^j] experienced by the population. We derive analytic results for the
law of , find which choice of the dispersal mechanism produces an
optimal stochastic growth rate for a freely dispersing population, and
investigate the effect on the stochastic growth rate of constraints on
dispersal rates. Our results provide fundamental insights into "ideal free"
movement in the face of uncertainty, the persistence of coupled sink
populations, the evolution of dispersal rates, and the single large or several
small (SLOSS) debate in conservation biology.Comment: 47 pages, 4 figure
Recommended from our members
Interactions between climate change and land use change on biodiversity: attribution problems, risks, and opportunities
Global change drivers are known to interact in their effects on biodiversity, but much research to date ignores this complexity. As a consequence, there are problems in the attribution of biodiversity change to different drivers and, therefore, our ability to manage habitats and landscapes appropriately. Few studies explicitly acknowledge and account for interactive (i.e., nonadditive) effects of land use and climate change on biodiversity. One reason is that the mechanisms by which drivers interact are poorly understood. We evaluate such mechanisms, including interactions between demographic parameters, evolutionary trade-offs and synergies and threshold effects of population size and patch occupancy on population persistence. Other reasons for the lack of appropriate research are limited data availability and analytical issues in addressing interaction effects. We highlight the influence that attribution errors can have on biodiversity projections and discuss experimental designs and analytical tools suited to this challenge. Finally, we summarize the risks and opportunities provided by the existence of interaction effects. Risks include ineffective conservation management; but opportunities also arise, whereby the negative impacts of climate change on biodiversity can be reduced through appropriate land management as an adaptation measure. We hope that increasing the understanding of key mechanisms underlying interaction effects and discussing appropriate experimental and analytical designs for attribution will help researchers, policy makers, and conservation practitioners to better minimize risks and exploit opportunities provided by land use-climate change interactions
'To live and die [for] Dixie': Irish civilians and the Confederate States of America
Around 20,000 Irishmen served in the Confederate army in the Civil War. As a result, they left behind, in various Southern towns and cities, large numbers of friends, family, and community leaders. As with native-born Confederates, Irish civilian support was crucial to Irish participation in the Confederate military effort. Also, Irish civilians served in various supporting roles: in factories and hospitals, on railroads and diplomatic missions, and as boosters for the cause. They also, however, suffered in bombardments, sieges, and the blockade. Usually poorer than their native neighbours, they could not afford to become 'refugees' and move away from the centres of conflict. This essay, based on research from manuscript collections, contemporary newspapers, British Consular records, and Federal military records, will examine the role of Irish civilians in the Confederacy, and assess the role this activity had on their integration into Southern communities. It will also look at Irish civilians in the defeat of the Confederacy, particularly when they came under Union occupation. Initial research shows that Irish civilians were not as upset as other whites in the South about Union victory. They welcomed a return to normalcy, and often 'collaborated' with Union authorities. Also, Irish desertion rates in the Confederate army were particularly high, and I will attempt to gauge whether Irish civilians played a role in this. All of the research in this paper will thus be put in the context of the Drew Gilpin Faust/Gary Gallagher debate on the influence of the Confederate homefront on military performance. By studying the Irish civilian experience one can assess how strong the Confederate national experiment was. Was it a nation without a nationalism
Scaling up the effects of inbreeding depression from individuals to metapopulations
Abstract Inbreeding is common in nature, and many laboratory studies have documented that inbreeding depression can reduce the fitness of individuals. Demonstrating the consequences of inbreeding depression on the growth and persistence of populations is more challenging because populations are often regulated by density- or frequency-dependent selection and influenced by demographic and environmental stochasticity. A few empirical studies have shown that inbreeding depression can increase extinction risk of local populations. The importance of inbreeding depression at the metapopulation level has been conjectured based on population-level studies but has not been evaluated. We quantified the impact of inbreeding depression affecting the fitness of individuals on metapopulation persistence in heterogeneous habitat networks of different sizes and habitat configuration in a context of natural butterfly metapopulations. We developed a spatial individual-based simulation model of metapopulations with explicit genetics. We used Approximate Bayesian Computation to fit the model to extensive demographic, genetic, and life-history data available for the well-studied Glanville fritillary butterfly (Melitaea cinxia) metapopulations in the Åland islands in SW Finland. We compared 18 semi-independent habitat networks differing in size and fragmentation. The results show that inbreeding is more frequent in small habitat networks, and consequently, inbreeding depression elevates extinction risks in small metapopulations. Metapopulation persistence and neutral genetic diversity maintained in the metapopulations increase with the total habitat amount in and mean patch size of habitat networks. Dispersal and mating behavior interact with landscape structure to determine how likely it is to encounter kin while looking for mates. Inbreeding depression can decrease the viability of small metapopulations even when they are strongly influenced by stochastic extinction-colonization dynamics and density-dependent selection. The findings from this study support that genetic factors, in addition to demographic factors, can contribute to extinctions of small local populations and also of metapopulations. This article is protected by copyright. All rights reserved.Peer reviewe
Shared decision‐making and maternity care in the deep learning age: Acknowledging and overcoming inherited defeaters
In recent years there has been an explosion of interest in Artificial Intelligence (AI) both in health care and academic philosophy. This has been due mainly to the rise of effective machine learning and deep learning algorithms, together with increases in data collection and processing power, which have made rapid progress in many areas. However, use of this technology has brought with it philosophical issues and practical problems, in particular, epistemic and ethical. In this paper the authors, with backgrounds in philosophy, maternity care practice and clinical research, draw upon and extend a recent framework for shared decision‐making (SDM) that identified a duty of care to the client's knowledge as a necessary condition for SDM. This duty entails the responsibility to acknowledge and overcome epistemic defeaters. This framework is applied to the use of AI in maternity care, in particular, the use of machine learning and deep learning technology to attempt to enhance electronic fetal monitoring (EFM). In doing so, various sub‐kinds of epistemic defeater, namely, transparent, opaque, underdetermined, and inherited defeaters are taxonomized and discussed. The authors argue that, although effective current or future AI‐enhanced EFM may impose an epistemic obligation on the part of clinicians to rely on such systems' predictions or diagnoses as input to SDM, such obligations may be overridden by inherited defeaters, caused by a form of algorithmic bias. The existence of inherited defeaters implies that the duty of care to the client's knowledge extends to any situation in which a clinician (or anyone else) is involved in producing training data for a system that will be used in SDM. Any future AI must be capable of assessing women individually, taking into account a wide range of factors including women's preferences, to provide a holistic range of evidence for clinical decision‐making
Anti-relapse neurons in the infralimbic cortex of rats drive relapse-suppression by drug omission cues
Drug addiction is a chronic relapsing disorder of compulsive drug use. Studies of the neurobehavioral factors that promote drug relapse have yet to produce an effective treatment. Here we take a different approach and examine the factors that suppress – rather than promote – relapse. Adapting Pavlovian procedures to suppress operant drug response, we determined the anti-relapse action of environmental cues that signal drug omission (unavailability) in rats. Under laboratory conditions linked to compulsive drug use and heightened relapse risk, drug omission cues suppressed three major modes of relapse-promotion (drug-predictive cues, stress, and drug exposure) for cocaine and alcohol. This relapse-suppression is partially driven by omission cue-reactive neurons, which constitute small subsets of glutamatergic and GABAergic cells, in the infralimbic cortex. Future studies of such neural activity-based cellular units (neuronal ensembles/memory engram cells) for relapse-suppression can be used to identify alternate targets for addiction medicine through functional characterization of anti-relapse mechanisms
Factors associated with commencing smoking in 12-year-old students in Catalonia (Spain): a cross-sectional population-based study
<p>Abstract</p> <p>Background</p> <p>Over the last decade notable progress has been made in developed countries on monitoring smoking although experimenting with cigarettes and smoking in young people remains a serious public health problem. This paper reports a cross-sectional study at the beginning of the 3-year follow-up community study TA_BES. The aim was to study the prevalence of smoking in addition to determining predictive factors for when smoking commences in a representative population of 12-year-old first year compulsory secondary education students.</p> <p>Methods</p> <p>Twenty-nine secondary schools (N = 29) from an area of Catalonia participated in the study. In these schools 2245 students answered a questionnaire to study the attitudes, behaviors, and tobacco consumption in the subject's surrounding circle and family in relation to smoking; carbon monoxide measurements were taken by means of co-oximetry on 2 different occasions. A smoker was defined as a student who had smoked daily or occasionally in the last 30 days. For non-smokers the criteria of not considering was set up for those who answered that in the future they would not be smokers and considering those who answered that they did not rule out becoming a smoker in the future.</p> <p>Results</p> <p>Among the total 2245 students included in the analysis 157(7%) were classified as smokers. Among non-smokers we differentiated between those not considering smoking 1757 (78.3%) and those considering smoking 288 (12.8%).</p> <p>Age is among the factors related to commencing smoking. The risk of becoming a smoker increases 2.27 times/year. The influence of the group of friends with a very high risk for boys OR 149.5 and lower, albeit high, in girls OR 38.1. Tobacco consumption of parents produces different effects in young people. A smoking father does not produce alterations in the smoking behavior of young people. However having a smoking mother or former smoking is a risk factor for boys and a protective factor for girls.</p> <p>We detected a gradual risk of becoming a smoker by means of the co-oximetry test. A boy/girl with a test between 6 p.p.m and 10 p.p.m increased the probability of smoking by 2.29 and co-oximetry values > 10 p.p.m multiplied the risk 4 times over.</p> <p>Conclusions</p> <p>Results indicate that the age of commencing smoking is maintained in spite of prevalence having decreased in the last few years. The risk factors identified should be used to involve families and the educational community by offering them tobacco weaning programmes.</p
- …