The Structure of Psychopathology in a Community Sample of Preschoolers

ERIC Educational Resources Information Center

Strickland, Jennifer; Keller, Jennifer; Lavigne, John V.; Gouze, Karen; Hopkins, Joyce; LeBailly, Susan

2011-01-01

Despite growing interest in the development of alternative diagnostic classification systems for psychopathology in young children, little is known about the adequacy of the DSM symptom structure for describing psychopathology in this population. This paper examines the fit of the DSM-IV emotional (ED) and disruptive behavior disorder (DD) symptom…

The impact of natural transformation on adaptation in spatially structured bacterial populations.

PubMed

Moradigaravand, Danesh; Engelstädter, Jan

2014-06-20

Recent studies have demonstrated that natural transformation and the formation of highly structured populations in bacteria are interconnected. In spite of growing evidence about this connection, little is known about the dynamics of natural transformation in spatially structured bacterial populations. In this work, we model the interdependency between the dynamics of the bacterial gene pool and those of environmental DNA in space to dissect the effect of transformation on adaptation. Our model reveals that even with only a single locus under consideration, transformation with a free DNA fragment pool results in complex adaptation dynamics that do not emerge in previous models focusing only on the gene shuffling effect of transformation at multiple loci. We demonstrate how spatial restriction on population growth and DNA diffusion in the environment affect the impact of transformation on adaptation. We found that in structured bacterial populations intermediate DNA diffusion rates predominantly cause transformation to impede adaptation by spreading deleterious alleles in the population. Overall, our model highlights distinctive evolutionary consequences of bacterial transformation in spatially restricted compared to planktonic bacterial populations.

OPTIMAL CONTROL THEORY FOR SUSTAINABLE ENVIRONMENTAL MANAGEMENT

EPA Science Inventory

With growing world population, diminishing resources, and realization of the harmful effects of various pollutants, research focus in environmental management has shifted towards sustainability. The goal of a sustainable management strategy is to promote the structure and operati...

Motor Gasoline Consumption 2008 - Historical Perspective and Short-Term Projections

EIA Publications

2008-01-01

This report reviews how gasoline markets relate to population, income, prices, and the growing role of ethanol. It also analyzes the structural shift in motor gasoline markets that took place in the late 1990s.

Urban Evolution: the Role of Water

EPA Science Inventory

The structure, function, and services of urban ecosystems evolve over time scales from seconds to centuries as Earth's population grows, infrastructure ages, and sociopolitical values alter them. In order to systematically study changes over time, the concept of "urban evolution...

A unified genetic association test robust to latent population structure for a count phenotype.

PubMed

Song, Minsun

2018-06-04

Confounding caused by latent population structure in genome-wide association studies has been a big concern despite the success of genome-wide association studies at identifying genetic variants associated with complex diseases. In particular, because of the growing interest in association mapping using count phenotype data, it would be interesting to develop a testing framework for genetic associations that is immune to population structure when phenotype data consist of count measurements. Here, I propose a solution for testing associations between single nucleotide polymorphisms and a count phenotype in the presence of an arbitrary population structure. I consider a classical range of models for count phenotype data. Under these models, a unified test for genetic associations that protects against confounding was derived. An algorithm was developed to efficiently estimate the parameters that are required to fit the proposed model. I illustrate the proposed approach using simulation studies and an empirical study. Both simulated and real-data examples suggest that the proposed method successfully corrects population structure. Copyright © 2018 John Wiley & Sons, Ltd.

Ramifying feedback networks, cross-scale interactions, and emergent quasi individuals in Conway's game of Life.

PubMed

Gotts, Nicholas M

2009-01-01

Small patterns of state 1 cells on an infinite, otherwise empty array of Conway's game of Life can produce sets of growing structures resembling in significant ways a population of spatially situated individuals in a nonuniform, highly structured environment. Ramifying feedback networks and cross-scale interactions play a central role in the emergence and subsequent dynamics of the quasi population. The implications are discussed: It is proposed that analogous networks and interactions may have been precursors to natural selection in the real world.

Obesity and heart failure with preserved ejection fraction: A growing problem.

PubMed

Prenner, Stuart B; Mather, Paul J

2017-12-14

Heart Failure with Preserved Ejection Fraction (HFpEF) is increasing in prevalence due to the aging of the United States population as well as the current obesity epidemic. While obesity is very common in patients with HFpEF, obesity may represent a specific phenotype of HFpEF characterized by unique hemodynamics and structural abnormalities. Obesity induces a systemic inflammatory response that may contribute to myocardial fibrosis and endothelial dysfunction. The most obese patients continue to be excluded from HFpEF clinical trials, and thus ongoing research is needed to determine the role of pharmacologic and interventional approaches in this growing population. Copyright © 2017 Elsevier Inc. All rights reserved.

Keeping up with the Globe.

ERIC Educational Resources Information Center

Woods, Jacqueline

2000-01-01

States that new populations with diverse learning needs, fierce competition in curriculum development and delivery, new trends and uses of technology, and a growing international marketplace requiring multi-cultural, multi-skilled workforces are driving major structural and philosophical changes in America's educational systems. Asserts that focus…

The Dependence of Galaxy Clustering on Stellar-mass Assembly History for LRGs

NASA Astrophysics Data System (ADS)

Montero-Dorta, Antonio D.; Pérez, Enrique; Prada, Francisco; Rodríguez-Torres, Sergio; Favole, Ginevra; Klypin, Anatoly; Cid Fernandes, Roberto; González Delgado, Rosa M.; Domínguez, Alberto; Bolton, Adam S.; García-Benito, Rubén; Jullo, Eric; Niemiec, Anna

2017-10-01

We analyze the spectra of 300,000 luminous red galaxies (LRGs) with stellar masses {M}* ≳ {10}11 {M}⊙ from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). By studying their star formation histories, we find two main evolutionary paths converging into the same quiescent galaxy population at z˜ 0.55. Fast-growing LRGs assemble 80% of their stellar mass very early on (z˜ 5), whereas slow-growing LRGs reach the same evolutionary state at z˜ 1.5. Further investigation reveals that their clustering properties on scales of ˜1-30 Mpc are, at a high level of significance, also different. Fast-growing LRGs are found to be more strongly clustered and reside in overall denser large-scale structure environments than slow-growing systems, for a given stellar-mass threshold. Our results show a dependence of clustering on a property that is directly related to the evolution of galaxies, I.e., the stellar-mass assembly history, for a homogeneous population of similar mass and color. In a forthcoming work, we will address the halo connection in the context of galaxy assembly bias.

The use of highway underpasses by large mammals in Virginia and factors influencing their effectiveness.

DOT National Transportation Integrated Search

2005-01-01

The rapid increase in animal-vehicle collisions on U.S. roadways is a growing concern in terms of human safety, property damage and injury costs, and viability of wildlife populations. Wildlife crossing structures are gaining national recognition by ...

Epigenetic Contributions to Cognitive Aging: Disentangling Mindspan and Lifespan

ERIC Educational Resources Information Center

Spiegel, Amy M.; Sewal, Angila S.; Rapp, Peter R.

2014-01-01

Epigenetic modifications of chromatin structure provide a mechanistic interface for gene-environment interactions that impact the individualization of health trajectories across the lifespan. A growing body of research indicates that dysfunctional epigenetic regulation contributes to poor cognitive outcomes among aged populations. Here we review…

The demographic consequences of growing older and bigger in oyster populations.

PubMed

Moore, Jacob L; Lipcius, Romuald N; Puckett, Brandon; Schreiber, Sebastian J

2016-10-01

Structured population models, particularly size- or age-structured, have a long history of informing conservation and natural resource management. While size is often easier to measure than age and is the focus of many management strategies, age-structure can have important effects on population dynamics that are not captured in size-only models. However, relatively few studies have included the simultaneous effects of both age- and size-structure. To better understand how population structure, particularly that of age and size, impacts restoration and management decisions, we developed and compared a size-structured integral projection model (IPM) and an age- and size-structured IPM, using a population of Crassostrea gigas oysters in the northeastern Pacific Ocean. We analyzed sensitivity of model results across values of local retention that give populations decreasing in size to populations increasing in size. We found that age- and size-structured models yielded the best fit to the demographic data and provided more reliable results about long-term demography. Elasticity analysis showed that population growth rate was most sensitive to changes in the survival of both large (>175 mm shell length) and small (<75 mm shell length) oysters, indicating that a maximum size limit, in addition to a minimum size limit, could be an effective strategy for maintaining a sustainable population. In contrast, the purely size-structured model did not detect the importance of large individuals. Finally, patterns in stable age and stable size distributions differed between populations decreasing in size due to limited local retention and populations increasing in size due to high local retention. These patterns can be used to determine population status and restoration success. The methodology described here provides general insight into the necessity of including both age- and size-structure into modeling frameworks when using population models to inform restoration and management decisions. © 2016 by the Ecological Society of America.

Participatory assessment of the health of Latino immigrant men in a community with a growing Latino population.

PubMed

Documėt, Patricia I; Kamouyerou, Andrea; Pesantes, Amalia; Macia, Laura; Maldonado, Hernan; Fox, Andrea; Bachurski, Leslie; Morgenstern, Dawn; Gonzalez, Miguel; Boyzo, Roberto; Guadamuz, Thomas

2015-02-01

Latino immigrant men are an understudied population in the US, especially in areas with small yet growing Latino populations. For this community-based participatory health assessment we conducted four focus groups and 66 structured surveys with Latino immigrant men, and 10 openended interviews with service providers. We analyzed transcripts using content analysis and survey data using Pearson Chi-square tests. Overall, 53% of participating men had not completed high school. Our findings suggest that their social circumstances precluded men from behaving in a way they believe would protect their health. Loneliness, fear and lack of connections prompted stress among men, who had difficulty locating healthcare services. Newly immigrated men were significantly more likely to experience depression symptoms. Latino immigrant men face social isolation resulting in negative health consequences, which are amplified by the new growth community context. Men can benefit from interventions aimed at building their social connections.

Comparative population structure of cavity-nesting sea ducks

USGS Publications Warehouse

Pearce, John M.; Eadie, John M.; Savard, Jean-Pierre L.; Christensen, Thomas K.; Berdeen, James; Taylor, Eric J.; Boyd, Sean; Einarsson, Árni

2014-01-01

A growing collection of mtDNA genetic information from waterfowl species across North America suggests that larger-bodied cavity-nesting species exhibit greater levels of population differentiation than smaller-bodied congeners. Although little is known about nest-cavity availability for these species, one hypothesis to explain differences in population structure is reduced dispersal tendency of larger-bodied cavity-nesting species due to limited abundance of large cavities. To investigate this hypothesis, we examined population structure of three cavity-nesting waterfowl species distributed across much of North America: Barrow's Goldeneye (Bucephala islandica), Common Goldeneye (B. clangula), and Bufflehead (B. albeola). We compared patterns of population structure using both variation in mtDNA control-region sequences and band-recovery data for the same species and geographic regions. Results were highly congruent between data types, showing structured population patterns for Barrow's and Common Goldeneye but not for Bufflehead. Consistent with our prediction, the smallest cavity-nesting species, the Bufflehead, exhibited the lowest level of population differentiation due to increased dispersal and gene flow. Results provide evidence for discrete Old and New World populations of Common Goldeneye and for differentiation of regional groups of both goldeneye species in Alaska, the Pacific Northwest, and the eastern coast of North America. Results presented here will aid management objectives that require an understanding of population delineation and migratory connectivity between breeding and wintering areas. Comparative studies such as this one highlight factors that may drive patterns of genetic diversity and population trends.

It's Not How Old You Are, It's How You Are Old. State Discourse on Successful Ageing in Singapore

ERIC Educational Resources Information Center

Brooke, Mark

2016-01-01

According to Asher and Nandy, the global population of seniors will increase to 1.41 million in 2030 and is predicted to further grow to 2 billion by 2050. This will cause a fundamental change in the world's ageing structure, with the number of seniors equal to the child population (0-14 years). Today, seniors are being encouraged to be part of…

Rethinking the influence of hydroelectric development on gene flow in a long-lived fish, the Lake Sturgeon Acipenser fulvescens

PubMed Central

McDougall, Craig A.; Welsh, Amy B.; Gosselin, Thierry; Anderson, W. Gary; Nelson, Patrick A.

2017-01-01

Many hydroelectric dams have been in place for 50 - >100 years, which for most fish species means that enough generations have passed for fragmentation induced divergence to have accumulated. However, for long-lived species such as Lake Sturgeon, Acipenser fulvescens, it should be possible to discriminate between historical population structuring and contemporary gene flow and improve the broader understanding of anthropogenic influence. On the Winnipeg River, Manitoba, two hypotheses were tested: 1) Measureable quantities of former reservoir dwelling Lake Sturgeon now reside downstream of the Slave Falls Generating Station, and 2) genetically differentiated populations of Lake Sturgeon occur upstream and downstream, a result of historical structuring. Genetic methods based on ten microsatellite markers were employed, and simulations were conducted to provide context. With regards to contemporary upstream to downstream contributions, the inclusion of length-at-age data proved informative. Both pairwise relatedness and Bayesian clustering analysis substantiated that fast-growing outliers, apparently entrained after residing in the upstream reservoir for several years, accounted for ~15% of the Lake Sturgeon 525–750 mm fork length captured downstream. With regards to historical structuring, upstream and downstream populations were found to be differentiated (FST = 0.011, and 0.013–0.014 when fast-growing outliers were excluded), and heterozygosity metrics were higher for downstream versus upstream juveniles. Historical asymmetric (downstream) gene flow in the vicinity of the generating station was the most logical explanation for the observed genetic structuring. In this section of the Winnipeg River, construction of a major dam does not appear to have fragmented a previously panmictic Lake Sturgeon population, but alterations to habitat may be influencing upstream to downstream contributions in unexpected ways. PMID:28329005

Rethinking the influence of hydroelectric development on gene flow in a long-lived fish, the Lake Sturgeon Acipenser fulvescens.

PubMed

McDougall, Craig A; Welsh, Amy B; Gosselin, Thierry; Anderson, W Gary; Nelson, Patrick A

2017-01-01

Many hydroelectric dams have been in place for 50 - >100 years, which for most fish species means that enough generations have passed for fragmentation induced divergence to have accumulated. However, for long-lived species such as Lake Sturgeon, Acipenser fulvescens, it should be possible to discriminate between historical population structuring and contemporary gene flow and improve the broader understanding of anthropogenic influence. On the Winnipeg River, Manitoba, two hypotheses were tested: 1) Measureable quantities of former reservoir dwelling Lake Sturgeon now reside downstream of the Slave Falls Generating Station, and 2) genetically differentiated populations of Lake Sturgeon occur upstream and downstream, a result of historical structuring. Genetic methods based on ten microsatellite markers were employed, and simulations were conducted to provide context. With regards to contemporary upstream to downstream contributions, the inclusion of length-at-age data proved informative. Both pairwise relatedness and Bayesian clustering analysis substantiated that fast-growing outliers, apparently entrained after residing in the upstream reservoir for several years, accounted for ~15% of the Lake Sturgeon 525-750 mm fork length captured downstream. With regards to historical structuring, upstream and downstream populations were found to be differentiated (FST = 0.011, and 0.013-0.014 when fast-growing outliers were excluded), and heterozygosity metrics were higher for downstream versus upstream juveniles. Historical asymmetric (downstream) gene flow in the vicinity of the generating station was the most logical explanation for the observed genetic structuring. In this section of the Winnipeg River, construction of a major dam does not appear to have fragmented a previously panmictic Lake Sturgeon population, but alterations to habitat may be influencing upstream to downstream contributions in unexpected ways.

Using DNA metabarcoding for simultaneous inference of common vampire bat diet and population structure.

PubMed

Bohmann, Kristine; Gopalakrishnan, Shyam; Nielsen, Martin; Nielsen, Luisa Dos Santos Bay; Jones, Gareth; Streicker, Daniel G; Gilbert, M Thomas P

2018-04-19

Metabarcoding diet analysis has become a valuable tool in animal ecology; however, co-amplified predator sequences are not generally used for anything other than to validate predator identity. Exemplified by the common vampire bat, we demonstrate the use of metabarcoding to infer predator population structure alongside diet assessments. Growing populations of common vampire bats impact human, livestock and wildlife health in Latin America through transmission of pathogens, such as lethal rabies viruses. Techniques to determine large-scale variation in vampire bat diet and bat population structure would empower locality- and species-specific projections of disease transmission risks. However, previously used methods are not cost-effective and efficient for large-scale applications. Using bloodmeal and faecal samples from common vampire bats from coastal, Andean and Amazonian regions of Peru, we showcase metabarcoding as a scalable tool to assess vampire bat population structure and feeding preferences. Dietary metabarcoding was highly effective, detecting vertebrate prey in 93.2% of the samples. Bats predominantly preyed on domestic animals, but fed on tapirs at one Amazonian site. In addition, we identified arthropods in 9.3% of samples, likely reflecting consumption of ectoparasites. Using the same data, we document mitochondrial geographic population structure in the common vampire bat in Peru. Such simultaneous inference of vampire bat diet and population structure can enable new insights into the interplay between vampire bat ecology and disease transmission risks. Importantly, the methodology can be incorporated into metabarcoding diet studies of other animals to couple information on diet and population structure. © 2018 The Authors. Molecular Ecology Resources Published by John Wiley & Sons Ltd.

Crystallography of metal–organic frameworks

PubMed Central

Gándara, Felipe; Bennett, Thomas D.

2014-01-01

Metal–organic frameworks (MOFs) are one of the most intensely studied material types in recent times. Their networks, resulting from the formation of strong bonds between inorganic and organic building units, offer unparalled chemical diversity and pore environments of growing complexity. Therefore, advances in single-crystal X-ray diffraction equipment and techniques are required to characterize materials with increasingly larger surface areas, and more complex linkers. In addition, whilst structure solution from powder diffraction data is possible, the area is much less populated and we detail the current efforts going on here. We also review the growing number of reports on diffraction under non-ambient conditions, including the response of MOF structures to very high pressures. Such experiments are important due to the expected presence of stresses in proposed applications of MOFs – evidence suggesting rich and complex behaviour. Given the entwined and inseparable nature of their structure, properties and applications, it is essential that the field of structural elucidation is able to continue growing and advancing, so as not to provide a rate-limiting step on characterization of their properties and incorporation into devices and applications. This review has been prepared with this in mind. PMID:25485136

Cooperation in group-structured populations with two layers of interactions

PubMed Central

Zhang, Yanling; Fu, Feng; Chen, Xiaojie; Xie, Guangming; Wang, Long

2015-01-01

Recently there has been a growing interest in studying multiplex networks where individuals are structured in multiple network layers. Previous agent-based simulations of games on multiplex networks reveal rich dynamics arising from interdependency of interactions along each network layer, yet there is little known about analytical conditions for cooperation to evolve thereof. Here we aim to tackle this issue by calculating the evolutionary dynamics of cooperation in group-structured populations with two layers of interactions. In our model, an individual is engaged in two layers of group interactions simultaneously and uses unrelated strategies across layers. Evolutionary competition of individuals is determined by the total payoffs accrued from two layers of interactions. We also consider migration which allows individuals to move to a new group within each layer. An approach combining the coalescence theory with the theory of random walks is established to overcome the analytical difficulty upon local migration. We obtain the exact results for all “isotropic” migration patterns, particularly for migration tuned with varying ranges. When the two layers use one game, the optimal migration ranges are proved identical across layers and become smaller as the migration probability grows. PMID:26632251

Toward the Structural Transformation of Schools: Innovations in Staffing

ERIC Educational Resources Information Center

Coggshall, Jane; Lasagna, Molly; Laine, Sabrina

2009-01-01

The troubled economy is driving school organizations to become more efficient and driving the business community to demand that schools produce graduates with different sets of skills. States are finally uniting around common student learning standards as the student population grows more diverse. And the new administration is pouring an…

Linguistic Intervention Techniques for At-Risk English Language Learners

ERIC Educational Resources Information Center

Schneider, Elke; Evers, Tsila

2009-01-01

In U.S. public schools, the population of nonnative speakers of English who are at risk for failing language requirements is growing. This article presents multisensory structured language (MSL) teaching strategies to remediate these students' difficulties in reading, writing, and speaking English. These strategies are underscored by recent…

Unpacking Parent Involvement: Korean American Parents' Collective Networking

ERIC Educational Resources Information Center

Lim, Minjung

2012-01-01

This study examines the ways in which a group of Korean American parents perceived and responded to institutional inequalities in a family-school partnership. In their school, which had a growing Asian population, the dominant group's middle-class perspective on parent involvement became normal and operated as an overarching structure. Drawing…

Evolutionary mixed games in structured populations: Cooperation and the benefits of heterogeneity

NASA Astrophysics Data System (ADS)

Amaral, Marco A.; Wardil, Lucas; Perc, Matjaž; da Silva, Jafferson K. L.

2016-04-01

Evolutionary games on networks traditionally involve the same game at each interaction. Here we depart from this assumption by considering mixed games, where the game played at each interaction is drawn uniformly at random from a set of two different games. While in well-mixed populations the random mixture of the two games is always equivalent to the average single game, in structured populations this is not always the case. We show that the outcome is, in fact, strongly dependent on the distance of separation of the two games in the parameter space. Effectively, this distance introduces payoff heterogeneity, and the average game is returned only if the heterogeneity is small. For higher levels of heterogeneity the distance to the average game grows, which often involves the promotion of cooperation. The presented results support preceding research that highlights the favorable role of heterogeneity regardless of its origin, and they also emphasize the importance of the population structure in amplifying facilitators of cooperation.

Evolutionary mixed games in structured populations: Cooperation and the benefits of heterogeneity.

PubMed

Amaral, Marco A; Wardil, Lucas; Perc, Matjaž; da Silva, Jafferson K L

2016-04-01

Evolutionary games on networks traditionally involve the same game at each interaction. Here we depart from this assumption by considering mixed games, where the game played at each interaction is drawn uniformly at random from a set of two different games. While in well-mixed populations the random mixture of the two games is always equivalent to the average single game, in structured populations this is not always the case. We show that the outcome is, in fact, strongly dependent on the distance of separation of the two games in the parameter space. Effectively, this distance introduces payoff heterogeneity, and the average game is returned only if the heterogeneity is small. For higher levels of heterogeneity the distance to the average game grows, which often involves the promotion of cooperation. The presented results support preceding research that highlights the favorable role of heterogeneity regardless of its origin, and they also emphasize the importance of the population structure in amplifying facilitators of cooperation.

Temporal analysis of genetic structure to assess population dynamics of reintroduced swift foxes.

PubMed

Cullingham, Catherine I; Moehrenschlager, Axel

2013-12-01

Reintroductions are increasingly used to reestablish species, but a paucity of long-term postrelease monitoring has limited understanding of whether and when viable populations subsequently persist. We conducted temporal genetic analyses of reintroduced populations of swift foxes (Vulpes velox) in Canada (Alberta and Saskatchewan) and the United States (Montana). We used samples collected 4 years apart, 17 years from the initiation of the reintroduction, and 3 years after the conclusion of releases. To assess program success, we genotyped 304 hair samples, subsampled from the known range in 2000 and 2001, and 2005 and 2006, at 7 microsatellite loci. We compared diversity, effective population size, and genetic connectivity over time in each population. Diversity remained stable over time and there was evidence of increasing effective population size. We determined population structure in both periods after correcting for differences in sample sizes. The geographic distribution of these populations roughly corresponded with the original release locations, which suggests the release sites had residual effects on the population structure. However, given that both reintroduction sites had similar source populations, habitat fragmentation, due to cropland, may be associated with the population structure we found. Although our results indicate growing, stable populations, future connectivity analyses are warranted to ensure both populations are not subject to negative small-population effects. Our results demonstrate the importance of multiple sampling years to fully capture population dynamics of reintroduced populations. Análisis Temporal de la Estructura Genética para Evaluar la Dinámica Poblacional de Zorros (Vulpes velox) Reintroducidos. © 2013 Society for Conservation Biology.

Fast–slow continuum and reproductive strategies structure plant life-history variation worldwide

PubMed Central

Salguero-Gómez, Roberto; Jones, Owen R.; Jongejans, Eelke; Blomberg, Simon P.; Hodgson, David J.; Mbeau-Ache, Cyril; Zuidema, Pieter A.; de Kroon, Hans; Buckley, Yvonne M.

2016-01-01

The identification of patterns in life-history strategies across the tree of life is essential to our prediction of population persistence, extinction, and diversification. Plants exhibit a wide range of patterns of longevity, growth, and reproduction, but the general determinants of this enormous variation in life history are poorly understood. We use demographic data from 418 plant species in the wild, from annual herbs to supercentennial trees, to examine how growth form, habitat, and phylogenetic relationships structure plant life histories and to develop a framework to predict population performance. We show that 55% of the variation in plant life-history strategies is adequately characterized using two independent axes: the fast–slow continuum, including fast-growing, short-lived plant species at one end and slow-growing, long-lived species at the other, and a reproductive strategy axis, with highly reproductive, iteroparous species at one extreme and poorly reproductive, semelparous plants with frequent shrinkage at the other. Our findings remain consistent across major habitats and are minimally affected by plant growth form and phylogenetic ancestry, suggesting that the relative independence of the fast–slow and reproduction strategy axes is general in the plant kingdom. Our findings have similarities with how life-history strategies are structured in mammals, birds, and reptiles. The position of plant species populations in the 2D space produced by both axes predicts their rate of recovery from disturbances and population growth rate. This life-history framework may complement trait-based frameworks on leaf and wood economics; together these frameworks may allow prediction of responses of plants to anthropogenic disturbances and changing environments. PMID:26699477

Fast-slow continuum and reproductive strategies structure plant life-history variation worldwide.

PubMed

Salguero-Gómez, Roberto; Jones, Owen R; Jongejans, Eelke; Blomberg, Simon P; Hodgson, David J; Mbeau-Ache, Cyril; Zuidema, Pieter A; de Kroon, Hans; Buckley, Yvonne M

2016-01-05

The identification of patterns in life-history strategies across the tree of life is essential to our prediction of population persistence, extinction, and diversification. Plants exhibit a wide range of patterns of longevity, growth, and reproduction, but the general determinants of this enormous variation in life history are poorly understood. We use demographic data from 418 plant species in the wild, from annual herbs to supercentennial trees, to examine how growth form, habitat, and phylogenetic relationships structure plant life histories and to develop a framework to predict population performance. We show that 55% of the variation in plant life-history strategies is adequately characterized using two independent axes: the fast-slow continuum, including fast-growing, short-lived plant species at one end and slow-growing, long-lived species at the other, and a reproductive strategy axis, with highly reproductive, iteroparous species at one extreme and poorly reproductive, semelparous plants with frequent shrinkage at the other. Our findings remain consistent across major habitats and are minimally affected by plant growth form and phylogenetic ancestry, suggesting that the relative independence of the fast-slow and reproduction strategy axes is general in the plant kingdom. Our findings have similarities with how life-history strategies are structured in mammals, birds, and reptiles. The position of plant species populations in the 2D space produced by both axes predicts their rate of recovery from disturbances and population growth rate. This life-history framework may complement trait-based frameworks on leaf and wood economics; together these frameworks may allow prediction of responses of plants to anthropogenic disturbances and changing environments.

Transcript analysis in two alfalfa salt tolerance selected breeding populations relative to a non-tolerant population.

PubMed

Gruber, M Y; Xia, J; Yu, M; Steppuhn, H; Wall, K; Messer, D; Sharpe, A G; Acharya, S N; Wishart, D S; Johnson, D; Miller, D R; Taheri, A

2017-02-01

With the growing limitations on arable land, alfalfa (a widely cultivated, low-input forage) is now being selected to extend cultivation into saline lands for low-cost biofeedstock purposes. Here, minerals and transcriptome profiles were compared between two new salinity-tolerant North American alfalfa breeding populations and a more salinity-sensitive western Canadian alfalfa population grown under hydroponic saline conditions. All three populations accumulated two-fold higher sodium in roots than shoots as a function of increased electrical conductivity. At least 50% of differentially expressed genes (p < 0.05) were down-regulated in the salt-sensitive population growing under high salinity, while expression remained unchanged in the saline-tolerant populations. In particular, most reduction in transcript levels in the salt-sensitive population was observed in genes specifying cell wall structural components, lipids, secondary metabolism, auxin and ethylene hormones, development, transport, signalling, heat shock, proteolysis, pathogenesis-response, abiotic stress, RNA processing, and protein metabolism. Transcript diversity for transcription factors, protein modification, and protein degradation genes was also more strongly affected in salt-tolerant CW064027 than in salt-tolerant Bridgeview and salt-sensitive Rangelander, while both saline-tolerant populations showed more substantial up-regulation in redox-related genes and B-ZIP transcripts. The report highlights the first use of bulked genotypes as replicated samples to compare the transcriptomes of obligate out-cross breeding populations in alfalfa.

Growing population causes of unemployment.

PubMed

1995-01-01

At the March, 1995, International Meeting on Population and Social Development in Copenhagen, during the session on unemployment, underemployment, and population it was stated that the problem of employment was the extent to which a nation's labor supply was not matched by labor demand or job opportunities. Population was thus a supply factor, and the country's economic situation was a demand factor. The demographic variables that were considered important in the supply of labor were: a) the size and rate of growth of the population, which was a function of the birth rate, the death rate, and migration; and b) the age structure of the population, which was also a product of the rate of growth of the population and its distribution. An imbalance between the supply of labor and the demand for it gave rise to unemployment and underemployment. The vicious cycle generated by a high dependency burden associated with a young age-structure led to low savings and investments, which in turn led to low economic growth and a low standard of living. This produced high fertility rates, which in turn heightened the dependency burden perpetuating the cycle. This vicious cycle could be broken at only two points: at the high fertility stage, primarily by introducing family planning programs; and at the stage of low economic growth, by adopting policies to accelerate economic growth. To be successful, however, both actions had to be pursued simultaneously. Numerous participants emphasized the global nature of the issue of unemployment and underemployment; the effects of international competition and restrictive trade policies on employment opportunities. The growing disparity between North and South had created a social injustice between countries. Several participants called for more humane policies that favored democracy and promoted human development, and asked for assistance to help create an enabling environment for social and economic development.

Genetic variation and early performance of Giant Sequoia in plantations

Treesearch

W. J. Libby

1986-01-01

Giant sequoia (Sequoiadendron giganteum [Lindl.] Buchholz) is genetically less variable than expected; furthermore, it is less variable and its populations are less structured than are several associated or related conifers. Giant sequoia seedlings from open-pollinated seeds of isolated trees or from small outlier groves do not survive and grow as...

What Should We Know about Developmental Education?

ERIC Educational Resources Information Center

Lake, Pat, Ed.

2001-01-01

This document argues that the availability of developmental education is essential to the well being of the American economy and social structure. By the year 2050, U.S. citizens will be older and nearly 50% will belong to a minority group. The fastest growing population is Hispanic American, resulting from immigration and higher birth rates. This…

Balancing Data, Time, and Expectations: The Complex Decision-­Making Environment of Enrollment Management

ERIC Educational Resources Information Center

Johnson, Adam W.

2016-01-01

As a growing entity within higher education organizational structures, enrollment managers (EMs) are primarily tasked with projecting, recruiting, and retaining the student population of their campuses. Enrollment managers are expected by institutional presidents as well as through industry standards to make data-driven planning decisions to reach…

Balancing Data, Time, and Expectations: The Complex Decision-Making Environment of Enrollment Management

ERIC Educational Resources Information Center

Johnson, Adam W.

2013-01-01

As a growing entity within higher education organizational structures, enrollment managers (EMs) are primarily tasked with projecting, recruiting, and retaining the student population of their campuses. Enrollment managers are expected by institutional presidents as well as through industry standards to make data-driven planning decisions to reach…

Syncretizing Students' Spheres of Influence: A Narrative Portrait of Parent and Teacher Expectation Alignment

ERIC Educational Resources Information Center

Travelute, Catherine

2017-01-01

The Spanish-speaking Hispano-Latino diaspora demographic is the largest and fastest-growing English-learning population in the United States. In response to the needs present in these student demographics, two Spanish-speaking mothers and two English-speaking teachers participated in semi-structured interviews regarding their purposes and…

Foliar manganese accumulation by Maytenus founieri (Celastraceae) in its native New Caledonian habitats: populational variation and localization by X-ray microanalysis.

PubMed

Fernando, D R; Woodrow, I E; Jaffré, T; Dumontet, V; Marshall, A T; Baker, A J M

2008-01-01

Hyperaccumulation by plants is a rare phenomenon that has potential practical benefits. The majority of manganese (Mn) hyperaccumulators discovered to date occur in New Caledonia, and little is known about their ecophysiology. This study reports on natural populations of one such species, the endemic shrub Maytenus founieri. Mean foliar Mn concentrations of two populations growing on ultramafic substrates with varying soil pHs were obtained. Leaf anatomies were examined by light microscopy, while the spatial distributions of foliar Mn in both populations were examined by qualitative scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). Plants growing on two different substrates were found to have very different mean dry weight (DW) foliar Mn concentrations. Light microscopy showed that the leaves had very distinct thick dermal structures, consisting of multiple layers of large cells in the hypodermis. In vivo X-ray microprobe analyses revealed that, in both populations, Mn sequestration occurred primarily in these dermal tissues. The finding here that foliar Mn is most highly localized in the nonphotosynthetic tissues of M. founieri contrasts with results from similar studies on other woody species that accumulate high Mn concentrations in their shoots.

Genetic diversity and structure of Capparis spinosa L. in Iran as revealed by ISSR markers.

PubMed

Ahmadi, Maryam; Saeidi, Hojjatollah

2018-05-01

Capparis spinosa L. (caper bush) is an economically and ecologically important perennial shrub that grows across different regions of Iran. In this study, the genetic diversity and population structure of Iranian genepool of C. spinosa is evaluated using Inter Simple Sequence Repeat (ISSR) markers. Using 10 ISSR primers, 387 DNA fragments (bands) were amplified from the genomic DNA of 92 individuals belonging to twenty-one populations of C . spinosa , of which 378 (97.7%) were polymorphic. High level of genetic diversity (percentage of polymorphic loci = 98.2%, h = 0.1382, I = 0.243), high genetic differentiation (G st  = 0.5234) and low gene flow (Nm = 0.4553) among populations were observed. Caper bush populations were divided into 4 groups in the dendrogram, PCoA plot and Bayesian clustering results, mostly corresponded to their geographic regions. The results showed that there are value in sampling Iranian caper bush populations to look for valuable alleles for use in plant breeding programs.

The marginal cost of public funds with an aging population.

PubMed

Wildasin, D E

1991-05-01

"As populations in the United States and other advanced economies grow older, the burden of social security and health care financing is expected to rise markedly. Payroll, income, and other taxes on working populations are projected to rise accordingly. The marginal welfare cost to workers of social security and other public expenditures is analyzed within the context of a two-period life cycle model. By relaxing separability assumptions that have become common in the literature, the theoretical structure properly incorporates the effect of these public expenditures on labor supply. Comparative statics results indicate that changing age structure is likely to raise the marginal welfare to workers of social security, education, and other public expenditures. Illustrative calculations for the United States confirm this result, suggesting that the cost to workers of incremental social security benefits may easily double by 2025-2050." excerpt

Age structure and capital dilution effects in neo-classical growth models.

PubMed

Blanchet, D

1988-01-01

Economists often over estimate capital dilution effects when applying neoclassical growth models which use age structured population and depreciation of capital stock. This occurs because capital stock is improperly characterized. A standard model which assumes a constant depreciation of capital intimates that a population growth rate equal to a negative constant savings ratio is preferable to any higher growth rate. Growth rates which are lower than a negative constant savings ratio suggest an ever growing capital/labor ratio and an ever growing standard of living, even if people do not save. This is suggested because the natural reduction of the capital stock through depreciation is slower than the population decrease which is simply unrealistic. This model overlooks the fact that low or negative growth rates result in an ageing of the capital stock, and this ageing subsequently results in an increase of the overall rate of capital depreciation. In that overly simplistic model, depreciation was assumed independent of the age of the captial stock. Incorporating depreciation as a variable into a model allows a more symmetric treatment of capital. Using models with heterogenous capital, this article explores what occurs when more than 1 kind of capital good is involved in production and when these various captial goods have different lengths of life. Applying economic models, it also examines what occurs when the length of life of capital may vary. These variations correct the negative impact that population growth can have on per capital production and consumption.

Sex and the single squirrel: a genetic view of forest management in the Pacific Northwest.

Treesearch

Sally Duncan

2003-01-01

Forest management throughout the world is producing simplified forests. There is growing concern that these forests maintain neither complete vertebrate communities nor conditions favorable to maintenance of genetic diversity of those vertebrate populations that do find habitat in simply structured stands. Genetics is increasingly being used as a basis for management...

The Role of Social Capital and School Structure on Latino Access to Elite Colleges

ERIC Educational Resources Information Center

Gonzalez, Jeremiah J.

2013-01-01

Latinos make up the fastest growing population in the United States. However, this group has some of the lowest educational outcomes (Gandara & Contreras, 2009). Although large numbers of Latinos fail to achieve high levels of academic success, some Latinos are able to accomplish educational outcomes that compare with those of the most…

The use of high-resolution infrared thermography (HRIT) for the study of ice nucleation and ice propagation in plants

USDA-ARS?s Scientific Manuscript database

Freezing events that occur when plants are actively growing can be a lethal event particularly if the plant has no freezing tolerance. Such frost events often have devastating effects on agricultural production and can also play an important role in shaping community structure in natural population...

Structure/function analysis of cotton-based peptide-cellulose conjugates: spatiotemporal/kinetic assessment of protease aerogels compared to nanocrystalline and paper cellulose

USDA-ARS?s Scientific Manuscript database

The growing incidence of chronic wounds in the world population has prompted increased interest in chronic wound dressings with protease-modulating activity and protease point of care sensors to treat and enable monitoring of elevated protease-based wound pathology. However, the overall design featu...

Age-class structure and variability of two populations of the bluemask darter etheostoma (Doration) sp.

USGS Publications Warehouse

Simmons, J.W.; Layzer, J.B.; Smith, D.D.

2008-01-01

The bluemask darter Etheostoma (Doration) sp. is an endangered fish endemic to the upper Caney Fork system in the Cumberland River drainage in central Tennessee. Darters (Etheostoma spp.) are typically short-lived and exhibit rapid growth that quickly decreases with age. Consequently, estimating age of darters from length-frequency distributions can be difficult and subjective. We used a nonparametric kernel density estimator to reduce subjectivity in estimating ages of bluemask darters. Data were collected from a total of 2926 bluemask darters from the Collins River throughout three growing seasons. Additionally, data were collected from 842 bluemask darters from the Rocky River during one growing season. Analysis of length-frequencies indicated the presence of four age classes in both rivers. In each river, the majority of the population was comprised of fish 0.05). In both rivers, females were more abundant than males.

The mutation-drift balance in spatially structured populations.

PubMed

Schneider, David M; Martins, Ayana B; de Aguiar, Marcus A M

2016-08-07

In finite populations the action of neutral mutations is balanced by genetic drift, leading to a stationary distribution of alleles that displays a transition between two different behaviors. For small mutation rates most individuals will carry the same allele at equilibrium, whereas for high mutation rates of the alleles will be randomly distributed with frequencies close to one half for a biallelic gene. For well-mixed haploid populations the mutation threshold is μc=1/2N, where N is the population size. In this paper we study how spatial structure affects this mutation threshold. Specifically, we study the stationary allele distribution for populations placed on regular networks where connected nodes represent potential mating partners. We show that the mutation threshold is sensitive to spatial structure only if the number of potential mates is very small. In this limit, the mutation threshold decreases substantially, increasing the diversity of the population at considerably low mutation rates. Defining kc as the degree of the network for which the mutation threshold drops to half of its value in well-mixed populations we show that kc grows slowly as a function of the population size, following a power law. Our calculations and simulations are based on the Moran model and on a mapping between the Moran model with mutations and the voter model with opinion makers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Genetic genealogy comes of age: perspectives on the use of deep-rooted pedigrees in human population genetics.

PubMed

Larmuseau, M H D; Van Geystelen, A; van Oven, M; Decorte, R

2013-04-01

In this article, we promote the implementation of extensive genealogical data in population genetic studies. Genealogical records can provide valuable information on the origin of DNA donors in a population genetic study, going beyond the commonly collected data such as residence, birthplace, language, and self-reported ethnicity. Recent studies demonstrated that extended genealogical data added to surname analysis can be crucial to detect signals of (past) population stratification and to interpret the population structure in a more objective manner. Moreover, when in-depth pedigree data are combined with haploid markers, it is even possible to disentangle signals of temporal differentiation within a population genetic structure during the last centuries. Obtaining genealogical data for all DNA donors in a population genetic study is a labor-intensive task but the vastly growing (genetic) genealogical databases, due to the broad interest of the public, are making this job more time-efficient if there is a guarantee for sufficient data quality. At the end, we discuss the advantages and pitfalls of using genealogy within sampling campaigns and we provide guidelines for future population genetic studies. Copyright © 2013 Wiley Periodicals, Inc.

The cobra's tongue: Rethinking the function of the "fishtail appendage" on the pitcher plant Darlingtonia californica.

PubMed

Armitage, David W

2016-04-01

Carnivorous pitcher plants employ a variety of putative adaptations for prey attraction and capture. One example is the peculiar forked "fishtail appendage", a foliar structure widely presumed to function as a prey attractant on adult leaves of Darlingtonia californica (Sarraceniaceae). This study tests the prediction that the presence of the appendage facilitates prey capture and can be considered an example of an adaptation to the carnivorous syndrome. In a field experiment following a cohort of Darlingtonia leaves over their growing season, before the pitcher traps opened, the fishtail appendages from half of the leaves were removed. Additionally, all appendages were removed from every plant at two small, isolated populations. After 54 and 104 d, prey items were collected to determine whether differences in prey composition and biomass existed between experimental and unmanipulated control leaves. Removal of the fishtail appendage did not reduce pitcher leaves' prey biomass nor alter their prey composition at either the level of individual leaves or entire populations. Fishtail appendages on plants growing in shaded habitats contained significantly greater chlorophyll concentrations than those on plants growing in full sun. These results call into question the longstanding assumption that the fishtail appendage on Darlingtonia is an adaptation critical for the attraction and capture of prey. I suggest alternative evolutionary explanations for the role of the fishtail structure and repropose a hypothesis on the mutualistic nature of pitcher plant-arthropod trophic interactions. © 2016 Botanical Society of America.

AFLPs reveal different population genetic structure under contrasting environments in the marine snail Nucella lapillus L.

PubMed

Carro, Belén; Quintela, María; Ruiz, José Miguel; Barreiro, Rodolfo

2012-01-01

Dispersal has received growing attention in marine ecology, particularly since evidence obtained with up-to-date techniques challenged the traditional view. The dogwhelk Nucella lapillus L., a sedentary gastropod with direct development, is a good example: dispersal was traditionally assumed to be limited until studies with microsatellites disputed this idea. To shed some light on this controversy, the genetic structure of dogwhelk populations in northwest Spain was investigated with highly polymorphic AFLP markers giving special attention to the influence of hydrodynamic stress. In agreement with the expectations for a poor disperser, our results show a significant genetic structure at regional (<200 km) and areal scales (<15 km). However, the spatial genetic structure varied with wave-exposure in the present case study: IBD was evident under sheltered conditions but absent from the exposed area where genetic differentiation was stronger. Our results provide evidence that differences in wave-exposure can exert a detectable influence on the genetic structure of coastal organisms, even in species without a planktonic larva.

Breast Cancer Screening among Dominican Latinas: A Closer Look at Fatalism and Other Social and Cultural Factors

ERIC Educational Resources Information Center

Abraído-Lanza, Ana F.; Martins, Mariana Cunha; Shelton, Rachel C.; Flórez, Karen R.

2015-01-01

With the marked increase of the Latino population in the United States during the past 20 years, there has been growing interest in the social, cultural, and structural factors that may impede breast cancer screening among Latino women, especially among those subgroups that have been understudied. Acculturation and fatalism are central cultural…

Flipping between Languages? An Exploratory Analysis of the Usage by Spanish-Speaking English Language Learner Tertiary Students of a Bilingual Probability Applet

ERIC Educational Resources Information Center

Lesser, Lawrence M.; Wagler, Amy E.; Salazar, Berenice

2016-01-01

English language learners (ELLs) are a rapidly growing part of the student population in many countries. Studies on resources for language learners--especially Spanish-speaking ELLs--have focused on areas such as reading, writing, and mathematics, but not introductory probability and statistics. Semi-structured qualitative interviews investigated…

World Population: Toward the Next Century. Revised Edition.

ERIC Educational Resources Information Center

Murphy, Elaine M.

This document consists of answers to questions on various aspects of world population. They are: What is the population of the world? How fast is the population of the world growing? When will the population of the world stop growing? Is the term "population explosion" accurate? Why did this sudden growth occur? Did people have more babies than…

Genetic diversity and population structure of leafy kale and Brassica rupestris Raf. in south Italy.

PubMed

Maggioni, Lorenzo; von Bothmer, Roland; Poulsen, Gert; Branca, Ferdinando; Bagger Jørgensen, Rikke

2014-12-01

Local varieties of leafy kales (Brassica oleracea L.) are grown in home gardens in Calabria and Sicily for self-consumption, in the same area where the wild relative Brassica rupestris Raf. also grows. With the use of AFLP markers, comparisons were made of the genetic diversity and population structure of ten wild and 22 cultivated populations, as well as of a hybrid population and of four commercial cultivars of different B. oleracea crops. The level of genetic diversity was higher in leafy kales than in wild populations and this diversity was mainly distributed within populations. Wild populations remained distinct from cultivated material. Additionally, most wild populations were distinctively isolated from each other. On the other hand, it was not possible to molecularly distinguish even geographically distant leafy kale populations from each other or from different B. oleracea crops. It was possible to detect inter-crossing between leafy kales and B. rupestris. Findings from this study illustrate the existing level of genetic diversity in the B. oleracea gene pool. Individual populations (either wild or leafy kales) with higher levels of genetic diversity have been identified and suggestions are given for an informed conservation strategy. Domestication hypotheses are also discussed. © 2015 The Authors.

Conservation Genetics of Two Highly Endangered and Poorly Known Species of Zamia (Zamiaceae: Cycadales) in Colombia.

PubMed

Aristizábal, Arturo; Tuberquia, Dino J; Sanín, María José

2018-05-11

Genetic diversity is key in providing the variation needed to face stochastic change. Increased habitat loss alters population size and dynamics posing serious threats to the conservation of wild species. Colombia has undergone massive deforestation over the last century, but harbors extraordinary high species diversity of genus Zamia (Cycadales); however, most of the species are under threat. In this study, we targeted the largest accessible remaining populations of 2 closely related species growing as endemics in the Magdalena Valley region of Colombia. We successfully transferred the SSR loci used in previous Zamia studies to these species. In total, we amplified 13 microsatellite loci in 3 wild populations, aiming at: 1) assessing genetic diversity and 2) understanding if the structure found between the 3 populations reflected species and population boundaries due to ecological and historical genetic isolation. We found that the actual population size does not reflect population genetic diversity with a small population (Perales) harboring the highest genetic diversity. In addition, all populations are highly structured regardless of species containment, all showing signs of genetic isolation. Given the high degree of ecological threat, and the inherent biological traits of Cycads, we provide information regarding the prioritization of populations for ex situ management.

Genetic structure of coexisting wild and managed agave populations: implications for the evolution of plants under domestication

PubMed Central

Figueredo, Carmen Julia; Casas, Alejandro; González-Rodríguez, Antonio; Nassar, Jafet M.; Colunga-GarcíaMarín, Patricia; Rocha-Ramírez, Víctor

2015-01-01

Domestication is a continuous evolutionary process guided by humans. This process leads to divergence in characteristics such as behaviour, morphology or genetics, between wild and managed populations. Agaves have been important resources for Mesoamerican peoples since prehistory. Some species are domesticated and others vary in degree of domestication. Agave inaequidens Koch is used in central Mexico to produce mescal, and a management gradient from gathered wild and silvicultural populations, as well as cultivated plantations, has been documented. Significant morphological differences were reported among wild and managed populations, and a high phenotypic variation in cultivated populations composed of plants from different populations. We evaluated levels of genetic diversity and structure associated with management, hypothesizing that high morphological variation would be accompanied by high genetic diversity in populations with high gene flow and low genetic structure among managed and unmanaged populations. Wild, silvicultural and cultivated populations were studied, collecting tissue of 19–30 plants per population. Through 10 nuclear microsatellite loci, we compared population genetic parameters. We analysed partition of variation associated with management categories to estimate gene flow among populations. Agave inaequidens exhibits high levels of genetic diversity (He = 0.707) and moderate genetic structure (FST = 0.112). No differences were found in levels of genetic diversity among wild (He = 0.704), silviculturally managed (He = 0.733) and cultivated (He = 0.698) populations. Bayesian analysis indicated that five genetic clusters best fit the data, with genetic groups corresponding to habitats where populations grow rather than to management. Migration rates ranged from zero between two populations to markedly high among others (M = 0.73–35.25). Natural mechanisms of gene flow and the dynamic management of agave propagules among populations favour gene flow and the maintenance of high levels of variation within all populations. The slight differentiation associated with management indicates that domestication is in an incipient stage. PMID:26433707

Selective toxin effects on faster and slower growing individuals in the formation of hormesis at the population level - A case study with Lactuca sativa and PCIB.

PubMed

Belz, Regina G; Sinkkonen, Aki

2016-10-01

Natural plant populations have large phenotypic plasticity that enhances acclimation to local stress factors such as toxin exposures. While consequences of high toxin exposures are well addressed, effects of low-dose toxin exposures on plant populations are seldom investigated. In particular, the importance of 'selective low-dose toxicity' and hormesis, i.e. stimulatory effects, has not been studied simultaneously. Since selective toxicity can change the size distribution of populations, we assumed that hormesis alters the size distribution at the population level, and investigated whether and how these two low-dose phenomena coexist. The study was conducted with Lactuca sativa L. exposed to the auxin-inhibitor 2-(p-chlorophenoxy)-2-methylpropionic acid (PCIB) in vitro. In two separate experiments, L. sativa was exposed to 12 PCIB doses in 24 replicates (50 plants/replicate). Shoot/root growth responses at the population level were compared to the fast-growing (≥90% percentile) and the slow-growing subpopulations (≤10% percentile) by Mann-Whitney U testing and dose-response modelling. In the formation of pronounced PCIB hormesis at the population level, low-dose effects proved selective, but widely stimulatory which seems to counteract low-dose selective toxicity. The selectivity of hormesis was dose- and growth rate-dependent. Stimulation occurred at lower concentrations and stimulation percentage was higher among slow-growing individuals, but partly or entirely masked at the population level by moderate or negligible stimulation among the faster growing individuals. We conclude that the hormetic effect up to the maximum stimulation may be primarily facilitated by an increase in size of the most slow-growing individuals, while thereafter it seems that mainly the fast-growing individuals contributed to the observed hormesis at the population level. As size distribution within a population is related to survival, our study hints that selective effects on slow- and fast-growing individuals may change population dynamics, providing that similar effects can be repeated under field conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

LOCAL POPULATION CHANGE AND VARIATIONS IN RACIAL INTEGRATION IN THE UNITED STATES, 2000-2010.

PubMed

Bellman, Benjamin; Spielman, Seth E; Franklin, Rachel S

2018-03-01

While population growth has been consistently tied to decreasing racial segregation at the metropolitan level in the United States, little work has been done to relate small-scale changes in population size to integration. We address this question through a novel technique that tracks population changes by race and ethnicity for comparable geographies in both 2000 and 2010. Using the Theil Index, we analyze the fifty most populous Metropolitan Statistical Areas in 2010 for changes in multigroup segregation. We classify local areas by their net population change between 2000 and 2010 using a novel unit of analysis based on aggregating census blocks. We find strong evidence that growing parts of rapidly growing metropolitan areas of the United States are crucial to understanding regional differences in segregation that have emerged in past decades. Multigroup segregation declined the most in growing parts of growing metropolitan areas. Comparatively, growing parts of shrinking or stagnant metropolitan areas were less diverse and had smaller declines in segregation. We also find that local areas with shrinking populations had disproportionately high minority representation in 2000 before population loss took place. We conclude that the regional context of population growth or decline has important consequences for the residential mixing of racial groups.

Population dynamics and evaluation of alternative management strategies for nonnative Lake Trout in Priest Lake, Idaho

USGS Publications Warehouse

Ng, Elizabeth L.; Fredericks, Jim P.; Quist, Michael C.

2016-01-01

Lake Trout Salvelinus namaycush have been introduced widely throughout the western USA to enhance recreational fisheries, but high predatory demand can create challenges for management of yield and trophy fisheries alike. Lake Trout were introduced to Priest Lake, Idaho, during the 1920s, but few fishery-independent data are available to guide current or future management actions. We collected fishery-independent data to describe population dynamics and evaluate potential management scenarios using an age-structured population model. Lake Trout in Priest Lake were characterized by fast growth at young ages, which resulted in young age at maturity. However, adult growth rates and body condition were lower than for other Lake Trout populations. High rates of skipped spawning (>50%) were also observed. Model projections indicated that the population was growing (λ = 1.03). Eradication could be achieved by increasing annual mortality to 0.32, approximately twice the current rate. A protected slot length limit could increase population length-structure, but few fish grew fast enough to exit the slot. In contrast, a juvenile removal scenario targeting age-2 to age-5 Lake Trout maintained short-term harvest of trophy-length individuals while reducing overall population abundance.

Evaluating the genetic impact of South and Southeast Asia on the peopling of Bangladesh.

PubMed

Sultana, Gazi Nurun Nahar; Sharif, Mohd Istiaq; Asaduzzaman, Md; Chaubey, Gyaneshwer

2015-11-01

Despite rapidly growing understandings and dependency on single nucleotide polymorphisms (SNPs), highly variable autosomal short tandem repeats (STRs) are still regarded as the most established method to differentiate individuals at forensic level. Here with large number of various ethnic groups we undertook this study to reveal the genetic structure of the most densely populated part of South Asia i.e. the Bangladesh. The purpose of this work was to estimate population parameters based on the allele frequencies obtained for 15 polymorphic autosomal STR loci investigated in caste and tribal populations from Bangladesh (n=706). We compared the results in a broader context by merging 24 different populations of Asia to pertain their affinity. Various statistical analyses suggested a clear cut demarcation of tribal and non-tribal in Bangladesh. Moreover, beside the phylogenetic structure of the studied populations, it is found that the mean heterozygosity value was highest among the populations of Bangladesh, likely because of gene flow from different directions. However, Tonchangya, Adi and Khumi showed sign of genetic isolation and reduced diversity, possibly as a result of genetic drift and/or strong founder effects working on small endogamous populations. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Genetic structure of Xiphinema pachtaicum and X. index populations based on mitochondrial DNA variation.

PubMed

Gutiérrez-Gutiérrez, Carlos; Castillo, Pablo; Cantalapiedra-Navarrete, Carolina; Landa, Blanca B; Derycke, Sofie; Palomares-Rius, Juan E

2011-10-01

The dagger nematodes Xiphinema pachtaicum and X. index are two of the most widespread and frequently occurring Xiphinema spp. co-infesting vineyards and other crops and natural habitats worldwide. Sexual reproduction is rare in these species. The primary objective of this study was to determine the genetic structure of X. pachtaicum and X. index populations using eight and seven populations, respectively, from different "wine of denomination of origin (D.O.) zones" in Spain and Sardinia (Italy), by studying mitochondrial (cytochrome oxidase c subunit 1 or COI) and nuclear (D2-D3 expansion segments of 28S rDNA) markers. Both Xiphinema spp. showed low intraspecific divergence among COI sequences, ranging from 0.2% (1 base substitution) to 2.3% (10 substitutions) in X. pachtaicum and from 0.2% (1 base substitution) to 0.4% (2 substitutions) in X. index. Population genetic structure was strong for both species. Nevertheless, molecular differences among grapevine-growing areas were not significant, and intrapopulation diversity was very low. It is hypothesized that this genetic homogeneity in the nematode populations reflects their predominant parthenogenetic reproduction mode and low dispersal abilities. Our results also show that X. pachtaicum populations in Spain have possibly been established from two different populations of origin. Results also demonstrated that the two DNA regions studied are suitable diagnostic markers for X. index and X. pachtaicum.

[On some characteristics of the population development in the Shenzhen Special Economic Region].

PubMed

Zhang, Z; Yang, Q; An, H; Fang, D

1984-03-29

Shenzhen was originally a town in Guandong Province. In 1979, it was made into a Special Economic Region in order to cope with the needs of modernization. Because of rapid economic development, the population has also been growing rapidly. Before 1979, the total population of Shenzhen was only 20,000, both industry and agriculture were backward, and the living standard was low. After it was made a Special Economic Region, its population figure reached 200,000 according to a 1982 report. The age structure of the local population is young, and there are more males than females. In the last two years, because of family planning measures, the natural population growth rate has shown an obvious downward trend. The population development of Shenzhen has several characteristics: 1) the pace of population growth is very fast; 2) the educational level for the population is high, and investment in education is emphasized; 3) population mobility is strong, and it has an extensive impact on the local market, transportation, and social order; 4) the social and economic systems of Hong Kong have a special influence on its population development. Special studies and discussions concerning how to control Shenzhen's population growth, how to determine the trends toward change in age structure, and how to promote population quality and spiritual civilization should be conducted according to characteristics of the local population development.

Are most samples of animals systematically biased? Consistent individual trait differences bias samples despite random sampling.

PubMed

Biro, Peter A

2013-02-01

Sampling animals from the wild for study is something nearly every biologist has done, but despite our best efforts to obtain random samples of animals, 'hidden' trait biases may still exist. For example, consistent behavioral traits can affect trappability/catchability, independent of obvious factors such as size and gender, and these traits are often correlated with other repeatable physiological and/or life history traits. If so, systematic sampling bias may exist for any of these traits. The extent to which this is a problem, of course, depends on the magnitude of bias, which is presently unknown because the underlying trait distributions in populations are usually unknown, or unknowable. Indeed, our present knowledge about sampling bias comes from samples (not complete population censuses), which can possess bias to begin with. I had the unique opportunity to create naturalized populations of fish by seeding each of four small fishless lakes with equal densities of slow-, intermediate-, and fast-growing fish. Using sampling methods that are not size-selective, I observed that fast-growing fish were up to two-times more likely to be sampled than slower-growing fish. This indicates substantial and systematic bias with respect to an important life history trait (growth rate). If correlations between behavioral, physiological and life-history traits are as widespread as the literature suggests, then many animal samples may be systematically biased with respect to these traits (e.g., when collecting animals for laboratory use), and affect our inferences about population structure and abundance. I conclude with a discussion on ways to minimize sampling bias for particular physiological/behavioral/life-history types within animal populations.

A continuously growing web-based interface structure databank

NASA Astrophysics Data System (ADS)

Erwin, N. A.; Wang, E. I.; Osysko, A.; Warner, D. H.

2012-07-01

The macroscopic properties of materials can be significantly influenced by the presence of microscopic interfaces. The complexity of these interfaces coupled with the vast configurational space in which they reside has been a long-standing obstacle to the advancement of true bottom-up material behavior predictions. In this vein, atomistic simulations have proven to be a valuable tool for investigating interface behavior. However, before atomistic simulations can be utilized to model interface behavior, meaningful interface atomic structures must be generated. The generation of structures has historically been carried out disjointly by individual research groups, and thus, has constituted an overlap in effort across the broad research community. To address this overlap and to lower the barrier for new researchers to explore interface modeling, we introduce a web-based interface structure databank (www.isdb.cee.cornell.edu) where users can search, download and share interface structures. The databank is intended to grow via two mechanisms: (1) interface structure donations from individual research groups and (2) an automated structure generation algorithm which continuously creates equilibrium interface structures. In this paper, we describe the databank, the automated interface generation algorithm, and compare a subset of the autonomously generated structures to structures currently available in the literature. To date, the automated generation algorithm has been directed toward aluminum grain boundary structures, which can be compared with experimentally measured population densities of aluminum polycrystals.

A Malthusian curb on spatial structure in microorganism populations.

PubMed

Martin, A P

2004-10-07

That all organisms are born in the company of a parent but die alone is a fundamental biological asymmetry. It has been suggested that this provides a deep-rooted source of spatial pattern formation for microorganisms even at the scale of the population. Such a theory, however, neglects the strong influence in nature of the limited and spatially variable availability of food. The tendency, first recognized by Thomas Malthus in the 18th century, of a population to out-strip its food resources will eventually lead, through local starvation, to the suppression of a heterogeneity growing within a population. Using a generic model it is demonstrated that including local food limitation of breeding strongly dampens spatial structure otherwise resulting from birth and death. The extent of this damping is shown to be a function of the strength of the coupling between organisms and their food and of the total abundance of organic material. Moreover, this work provides an example of a density-dependent process acting to diminish spatial structure rather than to create it and highlights the rich variety of behaviour that is missed by continuum models which fail to represent such local dynamics.

Factors influencing the ability of Listeria monocytogenes to pass through a membrane filter by active infiltration.

PubMed

Nakazawa, Kentaro; Hasegawa, Hiroyuki; Nakagawa, Yoji; Terao, Michinori; Matsuyama, Tohey

2005-11-01

Listeria monocytogenes infiltrated the reticulate structure of a membrane filter and passed through a filter with pore sizes of 0.45 microm and 0.2 microm in 6 to 24 h and 5 to 6 days, respectively. Flagellar motility and expansive pressure generated by the growing bacterial population were indicated as the driving forces of infiltration.

Population structure and linkage disequilibrium in Lupinus albus L. germplasm and its implication for association mapping

USDA-ARS?s Scientific Manuscript database

White lupin (Lupinus albus L.) has been around since 300 B.C. and is recognized for its ability to grow on poor soils and applications as green manure in addition to seed harvest. The seed has very high levels of protein (33-47%) and oil (6-13%). It also has many secondary metabolites that are pote...

Structural racism and health inequities in the USA: evidence and interventions.

PubMed

Bailey, Zinzi D; Krieger, Nancy; Agénor, Madina; Graves, Jasmine; Linos, Natalia; Bassett, Mary T

2017-04-08

Despite growing interest in understanding how social factors drive poor health outcomes, many academics, policy makers, scientists, elected officials, journalists, and others responsible for defining and responding to the public discourse remain reluctant to identify racism as a root cause of racial health inequities. In this conceptual report, the third in a Series on equity and equality in health in the USA, we use a contemporary and historical perspective to discuss research and interventions that grapple with the implications of what is known as structural racism on population health and health inequities. Structural racism refers to the totality of ways in which societies foster racial discrimination through mutually reinforcing systems of housing, education, employment, earnings, benefits, credit, media, health care, and criminal justice. These patterns and practices in turn reinforce discriminatory beliefs, values, and distribution of resources. We argue that a focus on structural racism offers a concrete, feasible, and promising approach towards advancing health equity and improving population health. Copyright © 2017 Elsevier Ltd. All rights reserved.

Airport Flight Departure Delay Model on Improved BN Structure Learning

NASA Astrophysics Data System (ADS)

Cao, Weidong; Fang, Xiangnong

An high score prior genetic simulated annealing Bayesian network structure learning algorithm (HSPGSA) by combining genetic algorithm(GA) with simulated annealing algorithm(SAA) is developed. The new algorithm provides not only with strong global search capability of GA, but also with strong local hill climb search capability of SAA. The structure with the highest score is prior selected. In the mean time, structures with lower score are also could be choice. It can avoid efficiently prematurity problem by higher score individual wrong direct growing population. Algorithm is applied to flight departure delays analysis in a large hub airport. Based on the flight data a BN model is created. Experiments show that parameters learning can reflect departure delay.

Population Genetic Structure of Apple Scab (Venturia inaequalis (Cooke) G. Winter) in Iran

PubMed Central

Ebrahimi, Leila; Fotuhifar, Khalil-Berdi; Javan Nikkhah, Mohammad; Naghavi, Mohammad-Reza; Baisakh, Niranjan

2016-01-01

The population genetic structure of 278 Venturia inaequalis isolates, collected from different apple cultivars of eighteen different provinces in Iran, was investigated using 22 polymorphic microsatellite markers. Analysis of molecular variation, Bayesian clustering and Nei's genetic distance analyses based on 88 microsatellite alleles indicated substantial levels of gene flow among the collection sites. Ninety three percent of the variation was observed among the individuals within the populations and only 7% variation was observed among the populations. Structure analysis grouped the isolates into two populations. Maximum number of pathogen genotypes (44) was observed in the North of Iran that grows various different apple cultivars. Investigation on the variation of the pathogen on different cultivars in the North of Iran suggested a significant differentiation of the pathogen populations between wild apple and commercial cultivars. During sampling, varying ranges of scab infection were observed on various apple cultivars in forests, monoculture and mix orchards. Wild type apple (Malus orientalis) along the Caspian Sea Coast had the most infection in comparison with the Iranian endemic and commercial cultivars. Based on the genetic analysis and host tracking scenario of the pathogen, it was presumed that Iran could potentially be the center of origin of V. inaequalis, which requires further detailed studies with isolates collected from different parts of central Asia and world for confirmation. PMID:27631622

Interprofessionalism: Educating to meet patient needs.

PubMed

Kirch, Darrell G; Ast, Cori

2015-01-01

Interprofessional teams in health care are showing promise in achieving the triple aim-providing better care for the individual patient, reducing costs, and improving population health. To complement current changes in health care delivery in the United States, there is a growing consensus among health professions educators that students should be trained in interprofessional models prior to entering clinical practice. Current interprofessional education (IPE) efforts in anatomy education are producing positive results in enhancing professional respect, collaboration, and teamwork among health professions students. In spite of existing structural and cultural barriers to IPE, health professions educators must continue to lead and grow IPE efforts as a critical component to improving the health of our nation. © 2014 American Association of Anatomists.

Wild European apple (Malus sylvestris (L.) Mill.) population dynamics: insight from genetics and ecology in the Rhine Valley. Priorities for a future conservation programme.

PubMed

Schnitzler, Annik; Arnold, Claire; Cornille, Amandine; Bachmann, Olivier; Schnitzler, Christophe

2014-01-01

The increasing fragmentation of forest habitats and the omnipresence of cultivars potentially threaten the genetic integrity of the European wild apple (Malus sylvestris (L.) Mill). However, the conservation status of this species remains unclear in Europe, other than in Belgium and the Czech Republic, where it has been declared an endangered species. The population density of M. sylvestris is higher in the forests of the upper Rhine Valley (France) than in most European forests, with an unbalanced age-structure, an overrepresentation of adults and a tendency to clump. We characterize here the ecology, age-structure and genetic diversity of wild apple populations in the Rhine Valley. We use these data to highlight links to the history of this species and to propose guidelines for future conservation strategies. In total, 255 individual wild apple trees from six forest stands (five floodplain forests and one forest growing in drier conditions) were analysed in the field, collected and genotyped on the basis of data for 15 microsatellite markers. Genetic analyses showed no escaped cultivars and few hybrids with the cultivated apple. Excluding the hybrids, the genetically "pure" populations displayed high levels of genetic diversity and a weak population structure. Age-structure and ecology studies of wild apple populations identified four categories that were not randomly distributed across the forests, reflecting the history of the Rhine forest over the last century. The Rhine wild apple populations, with their ecological strategies, high genetic diversity, and weak traces of crop-to-wild gene flow associated with the history of these floodplain forests, constitute candidate populations for inclusion in future conservation programmes for European wild apple.

Wild European Apple (Malus sylvestris (L.) Mill.) Population Dynamics: Insight from Genetics and Ecology in the Rhine Valley. Priorities for a Future Conservation Programme

PubMed Central

Schnitzler, Annik; Arnold, Claire; Cornille, Amandine; Bachmann, Olivier; Schnitzler, Christophe

2014-01-01

The increasing fragmentation of forest habitats and the omnipresence of cultivars potentially threaten the genetic integrity of the European wild apple (Malus sylvestris (L.) Mill). However, the conservation status of this species remains unclear in Europe, other than in Belgium and the Czech Republic, where it has been declared an endangered species. The population density of M. sylvestris is higher in the forests of the upper Rhine Valley (France) than in most European forests, with an unbalanced age-structure, an overrepresentation of adults and a tendency to clump. We characterize here the ecology, age-structure and genetic diversity of wild apple populations in the Rhine Valley. We use these data to highlight links to the history of this species and to propose guidelines for future conservation strategies. In total, 255 individual wild apple trees from six forest stands (five floodplain forests and one forest growing in drier conditions) were analysed in the field, collected and genotyped on the basis of data for 15 microsatellite markers. Genetic analyses showed no escaped cultivars and few hybrids with the cultivated apple. Excluding the hybrids, the genetically “pure” populations displayed high levels of genetic diversity and a weak population structure. Age-structure and ecology studies of wild apple populations identified four categories that were not randomly distributed across the forests, reflecting the history of the Rhine forest over the last century. The Rhine wild apple populations, with their ecological strategies, high genetic diversity, and weak traces of crop-to-wild gene flow associated with the history of these floodplain forests, constitute candidate populations for inclusion in future conservation programmes for European wild apple. PMID:24827575

Intergenerational relations and elder care preferences of Asian Indians in North Carolina.

PubMed

Sudha, S

2014-03-01

The US older population is growing in ethnic diversity. Persistent ethnic disparities in service use among seniors are linked to structural barriers to access, and also to family processes such as cultural preferences and intergenerational relations. There is sparse information on the latter issue for immigrant ethnic minority seniors. Information on the Asian group (the fastest growing senior sub-population) is extremely scarce, due to this group's diversity in national, linguistic, and cultural origins. We conducted a qualitative study among community-dwelling Asian Indian families (including at least one member aged 60 years and older) in North Carolina to examine preferences of seniors and the midlife generation regarding elder care, and the role of intergenerational relations in desired care for elders, exploring the theoretical perspective of intergenerational relationship ambivalence. Our results suggest that cultural preferences, ambivalence in intergenerational relations, and regulations on health service eligibility among immigrant/transnational seniors and midlife adults influence preferences for elder care.

Morphological change in machines accelerates the evolution of robust behavior

PubMed Central

Bongard, Josh

2011-01-01

Most animals exhibit significant neurological and morphological change throughout their lifetime. No robots to date, however, grow new morphological structure while behaving. This is due to technological limitations but also because it is unclear that morphological change provides a benefit to the acquisition of robust behavior in machines. Here I show that in evolving populations of simulated robots, if robots grow from anguilliform into legged robots during their lifetime in the early stages of evolution, and the anguilliform body plan is gradually lost during later stages of evolution, gaits are evolved for the final, legged form of the robot more rapidly—and the evolved gaits are more robust—compared to evolving populations of legged robots that do not transition through the anguilliform body plan. This suggests that morphological change, as well as the evolution of development, are two important processes that improve the automatic generation of robust behaviors for machines. It also provides an experimental platform for investigating the relationship between the evolution of development and robust behavior in biological organisms. PMID:21220304

A "carbonizing dragon": China's fast growing CO2 emissions revisited.

PubMed

Minx, Jan C; Baiocchi, Giovanni; Peters, Glen P; Weber, Christopher L; Guan, Dabo; Hubacek, Klaus

2011-11-01

China's annual CO(2) emissions grew by around 4 billion tonnes between 1992 and 2007. More than 70% of this increase occurred between 2002 and 2007. While growing export demand contributed more than 50% to the CO(2) emission growth between 2002 and 2005, capital investments have been responsible for 61% of emission growth in China between 2005 and 2007. We use structural decomposition analysis to identify the drivers for China's emission growth between 1992 and 2007, with special focus on the period 2002 to 2007 when growth was most rapid. In contrast to previous analysis, we find that efficiency improvements have largely offset additional CO(2) emissions from increased final consumption between 2002 and 2007. The strong increases in emissions growth between 2002 and 2007 are instead explained by structural change in China's economy, which has newly emerged as the third major emission driver. This structural change is mainly the result of capital investments, in particular, the growing prominence of construction services and their carbon intensive supply chain. By closing the model for capital investment, we can now show that the majority of emissions embodied in capital investment are utilized for domestic household and government consumption (35-49% and 19-36%, respectively) with smaller amounts for the production of exports (21-31%). Urbanization and the associated changes in lifestyle are shown to be more important than other socio-demographic drivers like the decreasing household size or growing population. We argue that mitigation efforts will depend on the future development of these key drivers, particularly capital investments which dictate future mitigation costs.

AFLPs Reveal Different Population Genetic Structure under Contrasting Environments in the Marine Snail Nucella lapillus L.

PubMed Central

Carro, Belén; Quintela, María; Ruiz, José Miguel; Barreiro, Rodolfo

2012-01-01

Dispersal has received growing attention in marine ecology, particularly since evidence obtained with up-to-date techniques challenged the traditional view. The dogwhelk Nucella lapillus L., a sedentary gastropod with direct development, is a good example: dispersal was traditionally assumed to be limited until studies with microsatellites disputed this idea. To shed some light on this controversy, the genetic structure of dogwhelk populations in northwest Spain was investigated with highly polymorphic AFLP markers giving special attention to the influence of hydrodynamic stress. In agreement with the expectations for a poor disperser, our results show a significant genetic structure at regional (<200 km) and areal scales (<15 km). However, the spatial genetic structure varied with wave-exposure in the present case study: IBD was evident under sheltered conditions but absent from the exposed area where genetic differentiation was stronger. Our results provide evidence that differences in wave-exposure can exert a detectable influence on the genetic structure of coastal organisms, even in species without a planktonic larva. PMID:23185435

Models of care and organization of services.

PubMed

Markova, Alina; Xiong, Michael; Lester, Jenna; Burnside, Nancy J

2012-01-01

This article examines the overall organization of services and delivery of health care in the United States. Health maintenance organization, fee-for-service, preferred provider organizations, and the Veterans Health Administration are discussed, with a focus on structure, outcomes, and areas for improvement. An overview of wait times, malpractice, telemedicine, and the growing population of physician extenders in dermatology is also provided. Copyright © 2012 Elsevier Inc. All rights reserved.

Interactions Between the Cross-Shore Structure of Small Pelagic Fish Population, Offshore Industrial Fisheries and Near Shore Artisanal Fisheries: A Mathematical Approach.

PubMed

Mchich, Rachid; Brochier, Timothée; Auger, Pierre; Brehmer, Patrice

2016-12-01

This work presents a mathematical model describing the interactions between the cross-shore structure of small pelagic fish population an their exploitation by coastal and offshore fisheries. The complete model is a system of seven ODE's governing three stocks of small pelagic fish population moving and growing between three zones. Two types of fishing fleets are inter-acting with the fish population, industrial boats, constrained to offshore area, and artisanal boats, operating from the shore. Two time scales were considered and we use aggregation methods that allow us to reduce the dimension of the model and to obtain an aggregated model, which is a four dimension one. The analysis of the aggregated model is performed. We discuss the possible equilibriums and their meaning in terms of fishery management. An interesting equilibrium state can be obtained for which we can expect coexistence and a stable equilibrium state between fish stocks and fishing efforts. Some identification parameters are also given in the discussion part of the model.

Optimal growth entails risky localization in population dynamics

NASA Astrophysics Data System (ADS)

Gueudré, Thomas; Martin, David G.

2018-03-01

Essential to each other, growth and exploration are jointly observed in alive and inanimate entities, such as animals, cells or goods. But how the environment's structural and temporal properties weights in this balance remains elusive. We analyze a model of stochastic growth with time correlations and diffusive dynamics that sheds light on the way populations grow and spread over general networks. This model suggests natural explanations of empirical facts in econo-physics or ecology, such as the risk-return trade-off and the Zipf law. We conclude that optimal growth leads to a localized population distribution, but such risky position can be mitigated through the space geometry. These results have broad applicability and are subsequently illustrated over an empirical study of financial data.

Bomb or Boon: Linking Population, People and Power in Fragile Regions: Comment on "The Pill Is Mightier Than the Sword".

PubMed

Gilpin, Raymond

2015-10-02

The relationship between population structure and violent conflict is complex and heavily dependent on the behavior of other variables like governance, economic prospects, and urbanization. While addressing rapid population growth might be a necessary condition for peace, it is by no means sufficient. Concomitant steps must also be taken to foster inclusivity, guarantee broader rights for all, particularly women, rebuild social contracts and ensure that all citizens have equal access to economic opportunity. Measures to control family size could reduce dependency and create greater socio-economic opportunities for women and youth, By so doing, the "youth bulge" phenomenon could be a boon for rapidly growing developing countries. © 2016 by Kerman University of Medical Sciences.

Growing food in urban areas: Food security, community benefits, any concerns?

USDA-ARS?s Scientific Manuscript database

Over 80% of our nation’s population lives in urban areas, including Minneapolis-Saint Paul, the 16th most populous metropolitan area in the USA, with 3.3 million inhabitants. Trends of growing urban populations and increased desire for locally sourced food have culminated in greater public interest...

Mindful attention and awareness: relationships with psychopathology and emotion regulation.

PubMed

Gregório, Sónia; Pinto-Gouveia, José

2013-01-01

The growing interest in mindfulness from the scientific community has originated several self-report measures of this psychological construct. The Mindful Attention and Awareness Scale (MAAS) is a self-report measure of mindfulness at a trait-level. This paper aims at exploring MAAS psychometric characteristics and validating it for the Portuguese population. The first two studies replicate some of the original author's statistical procedures in two different samples from the Portuguese general community population, in particular confirmatory factor analyses. Results from both analyses confirmed the scale single-factor structure and indicated a very good reliability. Moreover, cross-validation statistics showed that this single-factor structure is valid for different respondents from the general community population. In the third study the Portuguese version of the MAAS was found to have good convergent and discriminant validities. Overall the findings support the psychometric validity of the Portuguese version of MAAS and suggest this is a reliable self-report measure of trait-mindfulness, a central construct in Clinical Psychology research and intervention fields.

Host population genetic structure and zooxanthellae diversity of two reef-building coral species along the Florida Reef Tract and wider Caribbean

NASA Astrophysics Data System (ADS)

Baums, I. B.; Johnson, M. E.; Devlin-Durante, M. K.; Miller, M. W.

2010-12-01

In preparation for a large-scale coral restoration project, we surveyed host population genetic structure and symbiont diversity of two reef-building corals in four reef zones along the Florida reef tract (FRT). There was no evidence for coral population subdivision along the FRT in Acropora cervicornis or Montastraea faveolata based on microsatellite markers. However, in A. cervicornis, significant genetic differentiation was apparent when extending the analysis to broader scales (Caribbean). Clade diversity of the zooxanthellae differed along the FRT. A. cervicornis harbored mostly clade A with clade D zooxanthellae being prominent in colonies growing inshore and in the mid-channel zones that experience greater temperature fluctuations and receive significant nutrient and sediment input. M. faveolata harbored a more diverse array of symbionts, and variation in symbiont diversity among four habitat zones was more subtle but still significant. Implications of these results are discussed for ongoing restoration and conservation work.

Standing variation in spatially growing populations

NASA Astrophysics Data System (ADS)

Fusco, Diana; Gralka, Matti; Kayser, Jona; Hallatschek, Oskar

Patterns of genetic diversity not only reflect the evolutionary history of a species but they can also determine the evolutionary response to environmental change. For instance, the standing genetic diversity of a microbial population can be key to rescue in the face of an antibiotic attack. While genetic diversity is in general shaped by both demography and evolution, very little is understood when both factors matter, as e.g. for biofilms with pronounced spatial organization. Here, we quantitatively explore patterns of genetic diversity by using microbial colonies and well-mixed test tube populations as antipodal model systems with extreme and very little spatial structure, respectively. We find that Eden model simulations and KPZ theory can remarkably reproduce the genetic diversity in microbial colonies obtained via population sequencing. The excellent agreement allows to draw conclusions on the resilience of spatially-organized populations and to uncover new strategies to contain antibiotic resistance.

IPUMS: Detailed global data on population characteristics

NASA Astrophysics Data System (ADS)

Kugler, T.

2017-12-01

Many new and exciting sources of data on human population distributions based on remote sensing, mobile technology, and other mechanisms are becoming available. These new data sources often provide fine scale spatial and/or temporal resolution. However, they typically focus on the location of population, with little or no information on population characteristics. The large and growing collection of data available through the IPUMS family of products complements datasets that provide spatial and temporal detail but little attribute detail by providing the full depth of characteristics covered by population censuses, including demographic, household structure, economic, employment, education, and housing characteristics. IPUMS International provides census microdata for 85 countries. Microdata provide the responses to every census question for each individual in a sample of households. Microdata identify the sub-national geographic unit in which a household is located, but for confidentiality reasons, identified units must include a minimum population, typically 20,000 people. Small-area aggregate data often describe much smaller geographic units, enabling study of detailed spatial patterns of population characteristics. However the structure of aggregate data tables is highly heterogeneous across countries, census years, and even topics within a given census, making these data difficult to work with in any systematic way. A recently funded project will assemble small-area aggregate population and agricultural census data published by national statistical offices. Through preliminary work collecting and cataloging over 10,000 tables, we have identified a small number of structural families that can be used to organize the many different structures. These structural families will form the basis for software tools to document and standardize the tables for ingest into a common database. Both the microdata and aggregate data are made available through IPUMS Terra, facilitating integration with land use, land cover, climate, and other environmental data. These data can be used to address pressing global challenges, such as food and water security, development and deforestation, and environmentally-influenced migration.

Age, growth, and mortality of introduced flathead catfish in Atlantic rivers and a review of other populations

USGS Publications Warehouse

Kwak, T.J.; Pine, William E.; Waters, D.S.

2006-01-01

Knowledge of individual growth and mortality rates of an introduced fish population is required to determine the success and degree of establishment as well as to predict the fish's impact on native fauna. The age and growth of flathead catfish Pylodictis olivaris have been studied extensively in the species' native and introduced ranges, and estimates have varied widely. We quantified individual growth rates and age structure of three introduced flathead catfish populations in North Carolina's Atlantic slope rivers using sagittal otoliths, determined trends in growth rates over time, compared these estimates among rivers in native and introduced ranges, and determined total mortality rates for each population. Growth was significantly faster in the Northeast Cape Fear River (NECFR) than in the Lumber and Neuse rivers. Fish in the NECFR grew to a total length of 700 mm by age 7, whereas fish in the Neuse and Lumber river populations reached this length by 8 and 10 years, respectively. The growth rates of fish in all three rivers were consistently higher than those of native riverine populations, similar to those of native reservoir populations, and slower than those of other introduced riverine populations. In general, recent cohorts (1998-2001 year-classes) in these three rivers exhibited slower growth among all ages than did cohorts previous to the 1998 year-class. The annual total mortality rate was similar among the three rivers, ranging from 0.16 to 0.20. These mortality estimates are considerably lower than those from the Missouri and Mississippi rivers, suggesting relatively low fishing mortality for these introduced populations. Overall, flathead catfish populations in reservoirs grow faster than those in rivers, the growth rates of introduced populations exceed those of native populations, and eastern United States populations grow faster than those in western states. Such trends constitute critical information for understanding and managing local populations.

Moving forward in circles: challenges and opportunities in modelling population cycles.

PubMed

Barraquand, Frédéric; Louca, Stilianos; Abbott, Karen C; Cobbold, Christina A; Cordoleani, Flora; DeAngelis, Donald L; Elderd, Bret D; Fox, Jeremy W; Greenwood, Priscilla; Hilker, Frank M; Murray, Dennis L; Stieha, Christopher R; Taylor, Rachel A; Vitense, Kelsey; Wolkowicz, Gail S K; Tyson, Rebecca C

2017-08-01

Population cycling is a widespread phenomenon, observed across a multitude of taxa in both laboratory and natural conditions. Historically, the theory associated with population cycles was tightly linked to pairwise consumer-resource interactions and studied via deterministic models, but current empirical and theoretical research reveals a much richer basis for ecological cycles. Stochasticity and seasonality can modulate or create cyclic behaviour in non-intuitive ways, the high-dimensionality in ecological systems can profoundly influence cycling, and so can demographic structure and eco-evolutionary dynamics. An inclusive theory for population cycles, ranging from ecosystem-level to demographic modelling, grounded in observational or experimental data, is therefore necessary to better understand observed cyclical patterns. In turn, by gaining better insight into the drivers of population cycles, we can begin to understand the causes of cycle gain and loss, how biodiversity interacts with population cycling, and how to effectively manage wildly fluctuating populations, all of which are growing domains of ecological research. © 2017 John Wiley & Sons Ltd/CNRS.

Moving forward in circles: Challenges and opportunities in modeling population cycles

USGS Publications Warehouse

Barraquand, Frederic; Louca, Stilianos; Abbott, Karen C; Cobbold, Christina A; Cordoleani, Flora; DeAngelis, Donald L.; Elderd, Bret D; Fox, Jeremy W; Greenwood, Priscilla; Hilker, Frank M; Murray, Dennis; Stieha, Christopher R; Taylor, Rachel A; Vitense, Kelsey; Wolkowicz, Gail; Tyson, Rebecca C

2017-01-01

Population cycling is a widespread phenomenon, observed across a multitude of taxa in both laboratory and natural conditions. Historically, the theory associated with population cycles was tightly linked to pairwise consumer–resource interactions and studied via deterministic models, but current empirical and theoretical research reveals a much richer basis for ecological cycles. Stochasticity and seasonality can modulate or create cyclic behaviour in non-intuitive ways, the high-dimensionality in ecological systems can profoundly influence cycling, and so can demographic structure and eco-evolutionary dynamics. An inclusive theory for population cycles, ranging from ecosystem-level to demographic modelling, grounded in observational or experimental data, is therefore necessary to better understand observed cyclical patterns. In turn, by gaining better insight into the drivers of population cycles, we can begin to understand the causes of cycle gain and loss, how biodiversity interacts with population cycling, and how to effectively manage wildly fluctuating populations, all of which are growing domains of ecological research.

Competitive advantage and higher fitness in native populations of genetically structured planktonic diatoms.

PubMed

Sildever, Sirje; Sefbom, Josefin; Lips, Inga; Godhe, Anna

2016-12-01

It has been shown that the planktonic diatom Skeletonema from neighbouring areas are genetically differentiated despite absence of physical dispersal barriers. We revisited two sites, Mariager Fjord and Kattegat, NE Atlantic, and isolated new strains. Microsatellite genotyping and F-statistics revealed that the populations were genetically differentiated. An experiment was designed to investigate if populations are locally adapted and have a native competitive advantage. Ten strains from each location were grown individually in native and foreign water to investigate differences in produced biomass. Additionally, we mixed six pairs, one strain from each site, and let them grow together in native and foreign water. Strains from Mariager Fjord and Kattegat produced higher biomass in native water. In the competition experiment, strains from both sites displayed higher relative abundance and demonstrated competitive advantage in their native water. The cause of the differentiated growth is unknown, but could possibly be attributed to differences in silica concentration or viruses in the two water types. Our data show that dispersal potential does not influence the genetic structure of the populations. We conclude that genetic adaptation has not been overruled by gene flow, but instead the responses to different selection conditions are enforcing the observed genetic structure. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

The Oppression of Latina Mothers: Experiences of Exploitation, Violence, Marginalization, Cultural Imperialism, and Powerlessness in Their Everyday Lives.

PubMed

Ayón, Cecilia; Messing, Jill T; Gurrola, Maria; Valencia-Garcia, Dellanira

2018-06-01

Despite Latinos being the largest growing population in the United States, research has not examined the impact of social structures on the well-being of Latina immigrants; negative social discourse and restrictive laws exacerbate inequality and discrimination in this population. Through combined inductive/deductive analysis of in-depth semistructured interviews, we examined immigrant Mexican mothers' ( N = 32) descriptions of oppression in the United States. All five forms of oppression, described in Young's oppression framework are evident: exploitation, violence, marginalization, cultural imperialism, and powerlessness. Discrimination places a high burden on Latinas due to the intersection of forms of oppression and nondominant identities.

State geological surveys: Their growing national role in policy

USGS Publications Warehouse

Gerhard, L.C.

2000-01-01

State geological surveys vary in organizational structure, but are political powers in the field of geology by virtue of their intimate knowledge of and involvement in legislative and political processes. Origins of state geological surveys lie in the recognition of society that settlement and prosperity depended on access to a variety of natural resources, resources that are most familiar to geologists. As the surveys adapt to modern societal pressures, making geology serve the public has become the new mission for many state geological surveys. Geologic mapping was the foundation of most early surveys, and the state surveys have brought mapping back into the public realm to meet today's challenges of growing population density, living environment desires, and resource access.

What Role Can Immigration Play in Shaping Europe’s Future?

DTIC Science & Technology

2011-02-28

to the combined effect of the existing age structure of the population, a growing number of people who are living longer, and persistently low...challenges posed by this trend, European leaders must prepare timely and effective responses on both economic and demographic fronts. To the extent...likely answer and more useful and effective tool to support the labor market, sustain the European economies, as well as to replace below-replacement

Wired: impacts of increasing power line use by a growing bird population

NASA Astrophysics Data System (ADS)

Moreira, Francisco; Encarnação, Vitor; Rosa, Gonçalo; Gilbert, Nathalie; Infante, Samuel; Costa, Julieta; D'Amico, Marcello; Martins, Ricardo C.; Catry, Inês

2017-02-01

Power lines are increasingly widespread across many regions of the planet. Although these linear infrastructures are known for their negative impacts on bird populations, through collision and electrocution, some species take advantage of electricity pylons for nesting. In this case, estimation of the net impact of these infrastructures at the population level requires an assessment of trade-offs between positive and negative impacts. We compiled historical information (1958-2014) of the Portuguese white stork Ciconia ciconia population to analyze long-term changes in numbers, distribution range and use of nesting structures. White stork population size increased 660% up to 12000 breeding pairs between 1984 and 2014. In the same period, the proportion of nests on electricity pylons increased from 1% to 25%, likely facilitated by the 60% increase in the length of the very high tension power line grid (holding the majority of the nests) in the stork’s distribution range. No differences in breeding success were registered for storks nesting on electricity pylons versus other structures, but a high risk of mortality by collision and electrocution with power lines was estimated. We discuss the implications of this behavioral change, and of the management responses by power line companies, both for stork populations and for managers.

Environmental isolation explains Iberian genetic diversity in the highly homozygous model grass Brachypodium distachyon.

PubMed

Marques, Isabel; Shiposha, Valeriia; López-Alvarez, Diana; Manzaneda, Antonio J; Hernandez, Pilar; Olonova, Marina; Catalán, Pilar

2017-06-15

Brachypodium distachyon (Poaceae), an annual Mediterranean Aluminum (Al)-sensitive grass, is currently being used as a model species to provide new information on cereals and biofuel crops. The plant has a short life cycle and one of the smallest genomes in the grasses being well suited to experimental manipulation. Its genome has been fully sequenced and several genomic resources are being developed to elucidate key traits and gene functions. A reliable germplasm collection that reflects the natural diversity of this species is therefore needed for all these genomic resources. However, despite being a model plant, we still know very little about its genetic diversity. As a first step to overcome this gap, we used nuclear Simple Sequence Repeats (nSSR) to study the patterns of genetic diversity and population structure of B. distachyon in 14 populations sampled across the Iberian Peninsula (Spain), one of its best known areas. We found very low levels of genetic diversity, allelic number and heterozygosity in B. distachyon, congruent with a highly selfing system. Our results indicate the existence of at least three genetic clusters providing additional evidence for the existence of a significant genetic structure in the Iberian Peninsula and supporting this geographical area as an important genetic reservoir. Several hotspots of genetic diversity were detected and populations growing on basic soils were significantly more diverse than those growing in acidic soils. A partial Mantel test confirmed a statistically significant Isolation-By-Distance (IBD) among all studied populations, as well as a statistically significant Isolation-By-Environment (IBE) revealing the presence of environmental-driven isolation as one explanation for the genetic patterns found in the Iberian Peninsula. The finding of higher genetic diversity in eastern Iberian populations occurring in basic soils suggests that these populations can be better adapted than those occurring in western areas of the Iberian Peninsula where the soils are more acidic and accumulate toxic Al ions. This suggests that the western Iberian acidic soils might prevent the establishment of Al-sensitive B. distachyon populations, potentially causing the existence of more genetically depauperated individuals.

The Brain in Congenital Heart Disease across the Lifespan: The Cumulative Burden of Injury

PubMed Central

Marelli, Ariane; Miller, Steven P.; Marino, Bradley Scott; Jefferson, Angela L.; Newburger, Jane W.

2017-01-01

The number of patients surviving with congenital heart disease (CHD) has soared over the last three decades. Adults constitute the fastest growing segment of the CHD population, now outnumbering children. Research to date on the heart-brain intersection in this population has largely been focused on neurodevelopmental outcomes in childhood and adolescence. Mutations in genes that are highly expressed in heart and brain may cause cerebral dysgenesis. Together with altered cerebral perfusion in utero, these factors are associated with abnormalities of brain structure and brain immaturity in a significant portion of neonates with critical CHD even before they undergo cardiac surgery. In infancy and childhood, the brain may be affected by risk factors related to heart disease itself or to its interventional treatments. As children with CHD become adults, they increasingly develop heart failure, atrial fibrillation, hypertension, diabetes and coronary disease. These acquired cardiovascular comorbidities can be expected to have effects similar to those in the general population on cerebral blood flow, brain volumes, and dementia. In both children and adults, cardiovascular disease may have adverse effects on achievement, executive function, memory, language, social interactions, and quality of life. In summary, against the backdrop of shifting demographics, risk factors for brain injury in the CHD population are cumulative and synergistic. As neurodevelopmental sequelae in children with CHD evolve to cognitive decline or dementia during adulthood, a growing population of CHD can be expected to require support services. We highlight evidence gaps and future research directions. PMID:27185022

Genetic diversity and differentiation of yellowwood [Cladrastis kentukea (Dum.Cours.) Rudd] growing in the wild and in planted populations outside the natural range

Treesearch

Nicholas LaBonte; Jadelys Tonos; Colleen Hartel; Keith E. Woeste

2017-01-01

Yellowwood (Cladrastis kentukea) grows in small, widely scattered populations in the wild, but is also a popular ornamental tree that thrives when planted in urban areas outside its natural range. Since the small native populations of yellowwood in several states are considered at risk of extirpation, the cultivated population could serve as an ex...

MC1R Genotype and Plumage Colouration in the Zebra Finch (Taeniopygia guttata): Population Structure Generates Artefactual Associations

PubMed Central

Hoffman, Joseph I.; Krause, E. Tobias; Lehmann, Katrin; Krüger, Oliver

2014-01-01

Polymorphisms at the melanocortin-1 receptor (MC1R) gene have been linked to coloration in many vertebrate species. However, the potentially confounding influence of population structure has rarely been controlled for. We explored the role of the MC1R in a model avian system by sequencing the coding region in 162 zebra finches comprising 79 wild type and 83 white individuals from five stocks. Allelic counts differed significantly between the two plumage morphs at multiple segregating sites, but these were mostly synonymous. To provide a control, the birds were genotyped at eight microsatellites and subjected to Bayesian cluster analysis, revealing two distinct groups. We therefore crossed wild type with white individuals and backcrossed the F1s with white birds. No significant associations were detected in the resulting offspring, suggesting that our original findings were a byproduct of genome-wide divergence. Our results are consistent with a previous study that found no association between MC1R polymorphism and plumage coloration in leaf warblers. They also contribute towards a growing body of evidence suggesting that care should be taken to quantify, and where necessary control for, population structure in association studies. PMID:24489736

Ethnic and Gender Considerations in the Use of Facial Injectables: African-American Patients.

PubMed

Burgess, Cheryl; Awosika, Olabola

2015-11-01

The United States is becoming increasingly more diverse as the nonwhite population continues to rise faster than ever. By 2044, the US Census Bureau projects that greater than 50% of the US population will be of nonwhite descent. Ethnic patients are the quickest growing portion of the cosmetic procedures market, with African-Americans comprising 7.1% of the 22% of ethnic minorities who received cosmetic procedures in the United States in 2014. The cosmetic concerns and natural features of this ethnic population are unique and guided by differing structural and aging processes than their white counterparts. As people of color increasingly seek nonsurgical cosmetic procedures, dermatologists and cosmetic surgeons must become aware that the Westernized look does not necessarily constitute beauty in these diverse people. The use of specialized aesthetic approaches and understanding of cultural and ethnic-specific features are warranted in the treatment of these patients. This article will review the key principles to consider when treating African-American patients, including the average facial structure of African-Americans, the impact of their ethnicity on aging and structure of face, and soft-tissue augmentation strategies specific to African-American skin.

Excess of mutational jackpot events in expanding populations revealed by spatial Luria–Delbrück experiments

PubMed Central

Fusco, Diana; Gralka, Matti; Kayser, Jona; Anderson, Alex; Hallatschek, Oskar

2016-01-01

The genetic diversity of growing cellular populations, such as biofilms, solid tumours or developing embryos, is thought to be dominated by rare, exceptionally large mutant clones. Yet, the emergence of these mutational jackpot events is only understood in well-mixed populations, where they stem from mutations that arise during the first few cell divisions. To study jackpot events in spatially structured populations, we track mutant clones in microbial populations using fluorescence microscopy and population sequencing. High-frequency mutations are found to be massively enriched in microbial colonies compared with well-shaken liquid cultures, as a result of late-occurring mutations surfing at the edge of range expansions. Thus, jackpot events can be generated not only when mutations arise early but also when they occur at favourable locations, which exacerbates their role in adaptation and disease. In particular, because spatial competition with the wild type keeps most mutant clones in a quiescent state, strong selection pressures that kill the wild type promote drug resistance. PMID:27694797

Excess of mutational jackpot events in expanding populations revealed by spatial Luria-Delbrück experiments.

PubMed

Fusco, Diana; Gralka, Matti; Kayser, Jona; Anderson, Alex; Hallatschek, Oskar

2016-10-03

The genetic diversity of growing cellular populations, such as biofilms, solid tumours or developing embryos, is thought to be dominated by rare, exceptionally large mutant clones. Yet, the emergence of these mutational jackpot events is only understood in well-mixed populations, where they stem from mutations that arise during the first few cell divisions. To study jackpot events in spatially structured populations, we track mutant clones in microbial populations using fluorescence microscopy and population sequencing. High-frequency mutations are found to be massively enriched in microbial colonies compared with well-shaken liquid cultures, as a result of late-occurring mutations surfing at the edge of range expansions. Thus, jackpot events can be generated not only when mutations arise early but also when they occur at favourable locations, which exacerbates their role in adaptation and disease. In particular, because spatial competition with the wild type keeps most mutant clones in a quiescent state, strong selection pressures that kill the wild type promote drug resistance.

Mutant number distribution in an exponentially growing population

NASA Astrophysics Data System (ADS)

Keller, Peter; Antal, Tibor

2015-01-01

We present an explicit solution to a classic model of cell-population growth introduced by Luria and Delbrück (1943 Genetics 28 491-511) 70 years ago to study the emergence of mutations in bacterial populations. In this model a wild-type population is assumed to grow exponentially in a deterministic fashion. Proportional to the wild-type population size, mutants arrive randomly and initiate new sub-populations of mutants that grow stochastically according to a supercritical birth and death process. We give an exact expression for the generating function of the total number of mutants at a given wild-type population size. We present a simple expression for the probability of finding no mutants, and a recursion formula for the probability of finding a given number of mutants. In the ‘large population-small mutation’ limit we recover recent results of Kessler and Levine (2014 J. Stat. Phys. doi:10.1007/s10955-014-1143-3) for a fully stochastic version of the process.

[Djibouti].

PubMed

The capital of Djibouti is Djibouti. As of 1995, Djibouti had a population of 600,000 governed by a presidential regime. 1994 gross national product and per capita income were, respectively, $445.1 million and $830. Per capita income declined by 2.8% per year over the period 1985-94. In 1994, Djibouti owed $246.9 million, then being serviced at $13 million. For the same year, Djibouti exported $404 million in goods and services and imported $463.2 million. As of 1995, the population was growing in size by 2.6% annually. In 1992-93, life expectancy at birth was 48.3 years and the infant mortality rate was 115 per 1000 births. Other data are presented on the country's topography, climate and vegetation, demographics, principal cities, population distribution, religions, political structure, economics and finances, foreign commerce, and transportation and communications.

Low doses of six toxicants change plant size distribution in dense populations of Lactuca sativa.

PubMed

Belz, Regina G; Patama, Marjo; Sinkkonen, Aki

2018-08-01

Toxicants are known to have negligible or stimulatory, i.e. hormetic, effects at low doses below those that decrease the mean response of a plant population. Our earlier observations indicated that at such low toxicant doses the growth of very fast- and slow-growing seedlings is selectively altered, even if the population mean remains constant. Currently, it is not known how common these selective low-dose effects are, whether they are similar among fast- and slow-growing seedlings, and whether they occur concurrently with hormetic effects. We tested the response of Lactuca sativa in complete dose-response experiments to six different toxicants at doses that did not decrease population mean and beyond. The tested toxicants were IAA, parthenin, HHCB, 4-tert-octylphenol, glyphosate, and pelargonic acid. Each experiment consisted of 14,400-16,800 seedlings, 12-14 concentrations, 24 replicates per concentration and 50 germinated seeds per replicate. We analyzed the commonness of selective low-dose effects and explored if toxic effects and hormetic stimulation among fast- and slow-growing individuals occurred at the same concentrations as they occur at the population level. Irrespective of the observed response pattern and toxicant, selective low-dose effects were found. Toxin effects among fast-growing individuals usually started at higher doses compared to the population mean, while the opposite was found among slow-growing individuals. Very low toxin exposures tended to homogenize plant populations due to selective effects, while higher, but still hormetic doses tended to heterogenize plant populations. Although the extent of observed size segregation varied with the specific toxin tested, we conclude that a dose-dependent alteration in size distribution of a plant population may generally apply for many toxin exposures. Copyright © 2018 Elsevier B.V. All rights reserved.

An analysis of social consequences of rapid fertility decline in China.

PubMed

Liu, Z; Liu, L

1988-12-01

Rapid fertility decline in China has brought about 2 direct effects: 1) the natural increase of the population has slowed down, and 2) the age structure has changed from the young to the adult type. These 2 effects have caused a series of economic and social consequences. Rapid fertility decline increases the gross national product per capita and accelerates the improvement of people's lives. Rapid fertility decline slows population growth and speeds up the accumulation of capital and the development of the economy. Since 1981, accumulation growth has exceeded consumption growth. Fertility decline alleviates the enrollment pressure on primary and secondary schools, raises the efficiency of education funds, and promotes the popularization of education. The family planning program strengthens the maternal and child health care and the medical care systems. As the result of economic development, the people's nutritional levels are improving. The physical quality of teenagers has improved steadily. The change in the age structure will alleviate the tension of rapid population growth and benefit population control in the next century. Fertility decline forces the traditional attitude toward childbearing from "more children, more happiness" to improved quality of children. The rapid fertility decline has caused a great deal of concern both inside and outside China about the aging of the population. The labor force, however, will continue to grow for the next 60 years. At present, China's population problems are still those of population growth.

Optimal defense theory explains deviations from latitudinal herbivory defense hypothesis.

PubMed

Kooyers, Nicholas J; Blackman, Benjamin K; Holeski, Liza M

2017-04-01

The latitudinal herbivory defense hypothesis (LHDH) postulates that the prevalence of species interactions, including herbivory, is greater at lower latitudes, leading to selection for increased levels of plant defense. While latitudinal defense clines may be caused by spatial variation in herbivore pressure, optimal defense theory predicts that clines could also be caused by ecogeographic variation in the cost of defense. For instance, allocation of resources to defense may not increase plant fitness when growing seasons are short and plants must reproduce quickly. Here we use a common garden experiment to survey genetic variation for constitutive and induced phenylpropanoid glycoside (PPG) concentrations across 35 Mimulus guttatus populations over a ~13° latitudinal transect. Our sampling regime is unique among studies of the LHDH in that it allows us to disentangle the effects of growing season length from those of latitude, temperature, and elevation. For five of the seven PPGs surveyed, we find associations between latitude and plant defense that are robust to population structure. However, contrary to the LHDH, only two PPGs were found at higher levels in low latitude populations, and total PPG concentrations were higher at higher latitudes. PPG levels are strongly correlated with growing season length, with higher levels of PPGs in plants from areas with longer growing seasons. Further, flowering time is positively correlated with the concentration of nearly all PPGs, suggesting that there may be a strong trade-off between development time and defense production. Our results reveal that ecogeographic patterns in plant defense may reflect variation in the cost of producing defense compounds in addition to variation in herbivore pressure. Thus, the biogeographic pattern predicted by the LHDH may not be accurate because the underlying factors driving variation in defense, in this case, growing season length, are not always associated with latitude in the same manner. Given these results, we conclude that LHDH cannot be interpreted without considering life history, and we recommend that future work on the LHDH move beyond solely testing the core LHDH prediction and place greater emphasis on isolating agents of selection that generate spatial variation in defense and herbivore pressure. © 2017 by the Ecological Society of America.

On the Origin and Spread of the Scab Disease of Apple: Out of Central Asia

PubMed Central

Gladieux, Pierre; Zhang, Xiu-Guo; Afoufa-Bastien, Damien; Valdebenito Sanhueza, Rosa-Maria; Sbaghi, Mohamed; Le Cam, Bruno

2008-01-01

Background Venturia inaequalis is an ascomycete fungus responsible for apple scab, a disease that has invaded almost all apple growing regions worldwide, with the corresponding adverse effects on apple production. Monitoring and predicting the effectiveness of intervention strategies require knowledge of the origin, introduction pathways, and population biology of pathogen populations. Analysis of the variation of genetic markers using the inferential framework of population genetics offers the potential to retrieve this information. Methodology/Principal Findings Here, we present a population genetic analysis of microsatellite variation in 1,273 strains of V. inaequalis representing 28 orchard samples from seven regions in five continents. Analysis of molecular variance revealed that most of the variation (88%) was distributed within localities, which is consistent with extensive historical migrations of the fungus among and within regions. Despite this shallow population structure, clustering analyses partitioned the data set into separate groups corresponding roughly to geography, indicating that each region hosts a distinct population of the fungus. Comparison of the levels of variability among populations, along with coalescent analyses of migration models and estimates of genetic distances, was consistent with a scenario in which the fungus emerged in Central Asia, where apple was domesticated, before its introduction into Europe and, more recently, into other continents with the expansion of apple growing. Across the novel range, levels of variability pointed to multiple introductions and all populations displayed signatures of significant post-introduction increases in population size. Most populations exhibited high genotypic diversity and random association of alleles across loci, indicating recombination both in native and introduced areas. Conclusions/Significance Venturia inaequalis is a model of invasive phytopathogenic fungus that has now reached the ultimate stage of the invasion process with a broad geographic distribution and well-established populations displaying high genetic variability, regular sexual reproduction, and demographic expansion. PMID:18197265

Population Structure of Barley Landrace Populations and Gene-Flow with Modern Varieties

PubMed Central

Bellucci, Elisa; Bitocchi, Elena; Rau, Domenico; Nanni, Laura; Ferradini, Nicoletta; Giardini, Alessandro; Rodriguez, Monica; Attene, Giovanna; Papa, Roberto

2013-01-01

Landraces are heterogeneous plant varieties that are reproduced by farmers as populations that are subject to both artificial and natural selection. Landraces are distinguished by farmers due to their specific traits, and different farmers often grow different populations of the same landrace. We used simple sequence repeats (SSRs) to analyse 12 barley landrace populations from Sardinia from two collections spanning 10 years. We analysed the population structure, and compared the population diversity of the landraces that were collected at field level (population). We used a representative pool of barley varieties for diversity comparisons and to analyse the effects of gene flow from modern varieties. We found that the Sardinian landraces are a distinct gene pool from those of both two-row and six-row barley varieties. There is also a low, but significant, mean level and population-dependent level of introgression from the modern varieties into the Sardinian landraces. Moreover, we show that the Sardinian landraces have the same level of gene diversity as the representative sample of modern commercial varieties grown in Italy in the last decades, even within population level. Thus, these populations represent crucial sources of germplasm that will be useful for crop improvement and for population genomics studies and association mapping, to identify genes, loci and genome regions responsible for adaptive variations. Our data also suggest that landraces are a source of valuable germplasm for sustainable agriculture in the context of future climate change, and that in-situ conservation strategies based on farmer use can preserve the genetic identity of landraces while allowing adaptation to local environments. PMID:24386303

Water, climate change and society in Bangladesh

NASA Astrophysics Data System (ADS)

Thiele-Eich, I.; Simmer, C.

2017-12-01

Dhaka, the capital of Bangladesh with a population of over 17 million people, is among the top five coastal cities most vulnerable to climate change, with over 30 % of the population living in slums. Effective disaster mitigation and adaptation requires an understanding how hazards such as flooding impact the population. The impacts of climate change on flooding and thus livelihoods in the complex delta of the Ganges-Brahmaputra-Meghna rivers can not be treated isolated from other anthropogenic impacts due to e.g. the construction of dams as well as a growing population. We illustrate this by setting up a conceptual socio-hydrological causal network using the enhanced Driving force - Pressure - State - Impact - Response framework. The constructed socio-hydrological framework includes both natural and anthropogenic processes and their two-way feedbacks, allowing policy makers to know where available resources can be used effectively to increase resilience and reduce vulnerability. We conclude that climate change takes place over long stretches of time and thus enable the population of Bangladesh to adapt slowly. Resources such as social capital, which is one of the main tools for slum dwellers to be able to cope with flooding can be altered over time, and as such the system can be considered overall stable and resilient. However, transboundary water sharing issues during the dry season and other implications resulting from dam structures such as Farakka Barrage complicate a prognosis on how the rapidly growing population will be affected in the 21st century. This is particularly important in connection with previous findings, which suggest that the Greater Dhaka population already experience a significant increase in mortality during droughts. Climate change can thus be seen as an anthropogenic amplification of the socio-hydrological challenges already faced by Bangladesh today.

Highway safety needs of U.S. Hispanic communities : issues and strategies

DOT National Transportation Integrated Search

1995-09-01

Growing diversity within the U.S. population is presenting new challenges to the National Highway Traffic Safety Administration and other agencies that serve the public. One of the fastest growing demographic groups is the Hispanic population. The te...

Highway Safety Needs of U.S. Hispanic Communities: Issues and Strategies

DOT National Transportation Integrated Search

1995-09-01

Growing diversity within the U.S. population is presenting new challenges to the National Highway Traffic Safety Administration and other agencies that serve the public. One of the fastest growing demographic groups is the Hispanic population. The te...

Teaching the Growing Population of Nontraditional Students.

ERIC Educational Resources Information Center

Wagner, June G.

2002-01-01

This document contains three articles on teaching the growing population of nontraditional students. "The Changing Demographics of the Classroom" defines "nontraditional students"; reviews the characteristics, risk factors, and special needs of nontraditional students; and identifies the following services as particularly important to…

Fishing, fast growth and climate variability increase the risk of collapse

PubMed Central

Pinsky, Malin L.; Byler, David

2015-01-01

Species around the world have suffered collapses, and a key question is why some populations are more vulnerable than others. Traditional conservation biology and evidence from terrestrial species suggest that slow-growing populations are most at risk, but interactions between climate variability and harvest dynamics may alter or even reverse this pattern. Here, we test this hypothesis globally. We use boosted regression trees to analyse the influences of harvesting, species traits and climate variability on the risk of collapse (decline below a fixed threshold) across 154 marine fish populations around the world. The most important factor explaining collapses was the magnitude of overfishing, while the duration of overfishing best explained long-term depletion. However, fast growth was the next most important risk factor. Fast-growing populations and those in variable environments were especially sensitive to overfishing, and the risk of collapse was more than tripled for fast-growing when compared with slow-growing species that experienced overfishing. We found little evidence that, in the absence of overfishing, climate variability or fast growth rates alone drove population collapse over the last six decades. Expanding efforts to rapidly adjust harvest pressure to account for climate-driven lows in productivity could help to avoid future collapses, particularly among fast-growing species. PMID:26246548

Fishing, fast growth and climate variability increase the risk of collapse.

PubMed

Pinsky, Malin L; Byler, David

2015-08-22

Species around the world have suffered collapses, and a key question is why some populations are more vulnerable than others. Traditional conservation biology and evidence from terrestrial species suggest that slow-growing populations are most at risk, but interactions between climate variability and harvest dynamics may alter or even reverse this pattern. Here, we test this hypothesis globally. We use boosted regression trees to analyse the influences of harvesting, species traits and climate variability on the risk of collapse (decline below a fixed threshold) across 154 marine fish populations around the world. The most important factor explaining collapses was the magnitude of overfishing, while the duration of overfishing best explained long-term depletion. However, fast growth was the next most important risk factor. Fast-growing populations and those in variable environments were especially sensitive to overfishing, and the risk of collapse was more than tripled for fast-growing when compared with slow-growing species that experienced overfishing. We found little evidence that, in the absence of overfishing, climate variability or fast growth rates alone drove population collapse over the last six decades. Expanding efforts to rapidly adjust harvest pressure to account for climate-driven lows in productivity could help to avoid future collapses, particularly among fast-growing species. © 2015 The Author(s).

Population density controls on microbial pollution across the Ganga catchment.

PubMed

Milledge, D G; Gurjar, S K; Bunce, J T; Tare, V; Sinha, R; Carbonneau, P E

2018-01-01

For millions of people worldwide, sewage-polluted surface waters threaten water security, food security and human health. Yet the extent of the problem and its causes are poorly understood. Given rapid widespread global urbanisation, the impact of urban versus rural populations is particularly important but unknown. Exploiting previously unpublished archival data for the Ganga (Ganges) catchment, we find a strong non-linear relationship between upstream population density and microbial pollution, and predict that these river systems would fail faecal coliform standards for irrigation waters available to 79% of the catchment's 500 million inhabitants. Overall, this work shows that microbial pollution is conditioned by the continental-scale network structure of rivers, compounded by the location of cities whose growing populations contribute c. 100 times more microbial pollutants per capita than their rural counterparts. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Global population structure and adaptive evolution of aflatoxin-producing fungi.

PubMed

Moore, Geromy G; Olarte, Rodrigo A; Horn, Bruce W; Elliott, Jacalyn L; Singh, Rakhi; O'Neal, Carolyn J; Carbone, Ignazio

2017-11-01

Aflatoxins produced by several species in Aspergillus section Flavi are a significant problem in agriculture and a continuous threat to human health. To provide insights into the biology and global population structure of species in section Flavi , a total of 1,304 isolates were sampled across six species ( A. flavus, A. parasiticus, A. nomius, A. caelatus, A. tamarii, and A. alliaceus ) from single fields in major peanut-growing regions in Georgia (USA), Australia, Argentina, India, and Benin (Africa). We inferred maximum-likelihood phylogenies for six loci, both combined and separately, including two aflatoxin cluster regions ( aflM/alfN and aflW/aflX ) and four noncluster regions ( amdS, trpC, mfs and MAT ), to examine population structure and history. We also employed principal component and STRUCTURE analysis to identify genetic clusters and their associations with six different categories (geography, species, precipitation, temperature, aflatoxin chemotype profile, and mating type). Overall, seven distinct genetic clusters were inferred, some of which were more strongly structured by G chemotype diversity than geography. Populations of A. flavus S in Benin were genetically distinct from all other section Flavi species for the loci examined, which suggests genetic isolation. Evidence of trans-speciation within two noncluster regions, whereby A. flavus S BG strains from Australia share haplotypes with either A. flavus or A. parasiticus , was observed. Finally, while clay soil and precipitation may influence species richness in Aspergillus section Flavi , other region-specific environmental and genetic parameters must also be considered.

The Effects of Targeted, Connectivism-Based Information Literacy Instruction on Latino Students Information Literacy Skills and Library Usage Behavior

ERIC Educational Resources Information Center

Walsh, John

2013-01-01

The United States is experiencing a socio-demographic shift in population and education. Latinos are the fastest growing segment of the population on the national level and in higher education. The Latino student population growth rate and Latino college completion rate are not reciprocal. While Latino students are the fastest growing demographic…

Imaging the Population Dynamics of Bacterial Communities in the Zebrafish Gut

NASA Astrophysics Data System (ADS)

Jemielita, Matthew; Taormina, Michael; Burns, Adam; Zac Stephens, W.; Hampton, Jennifer; Guillemin, Karen; Parthasarathy, Raghuveer

2013-03-01

The vertebrate gut is home to a diverse microbial ecosystem whose composition has a strong influence on the development and health of the host organism. While researchers are increasingly able to identify the constituent members of the microbiome, very little is known about the spatial and temporal dynamics of commensal microbial communities, including the mechanisms by which communities nucleate, grow, and interact. We address these issues using a model organism: the larval zebrafish (Danio rerio) prepared microbe-free and inoculated with controlled compositions of fluorophore-expressing bacteria. Live imaging with light sheet fluorescence microscopy enables visualization of individual bacterial cells as well as growing colonies over the entire volume of the gut over periods up to 24 hours. We analyze the structure and dynamics of imaged bacterial communities, uncovering correlations between population size, growth rates, and the timing of inoculations that suggest the existence of active changes in the host environment induced by early bacterial exposure. Our data provide the first visualizations of gut microbiota development over an extended period of time in a vertebrate.

Children in an aging society.

PubMed

Uhlenberg, Peter

2009-06-01

This article explores ways in which population aging in the United States between 2010 and 2030 might impact the well-being of children, with a distinction made between advantaged and disadvantaged children. A variety of economic and demographic statistics are used to describe the changing age structure of the population and changing public spending on older people and children. Data from the 1985 General Social Survey and Wave 2 of the National Survey of Families and Households are also used to examine connections between older people and children. In recent decades, there has been a graying of the federal budget, and programs for children have received a declining proportion of domestic spending. These trends will be exaggerated between 2010 and 2030 unless structural changes occur. Grandparents may provide increasing resources for their grandchildren. Age segregation results in relatively few older people being directly involved with children not related to them by kinship. The implications of population aging for children are relevant primarily for disadvantaged children. Disadvantaged children have grandparents with fewest resources and are most in need of public spending. As costs of supporting the older population increase, intentional social changes will be needed to prevent growing inequality among children.

High tunnels: protection for rather than from insect pests?

PubMed

Ingwell, Laura L; Thompson, Sarah L; Kaplan, Ian; Foster, Ricky E

2017-12-01

High tunnels are a season extension tool creating a hybrid of field and greenhouse growing conditions. High tunnels have recently increased in the USA and thus research on their management is lacking. One purported advantage of these structures is protection from common field pests, but evidence to support this claim is lacking. We compared insect pest populations in high tunnels with field production over two years for three crops: tomato, broccoli and cucumber. Greenhouse pests (e.g. aphids, whiteflies) were more prevalent in high tunnels, compared to field plots. Hornworms (tobacco (Manduca sexta L.) and tomato (M. quinquemaculata Haworth)), a common field pest on tomato, were also more abundant in high tunnels, requiring chemical control while field populations were low. The crucifer caterpillar complex (imported cabbageworm (Pieris rapae L.), diamondback moth (Plutella xylostella L.) and cabbage looper (Trichoplusia ni Hübner)) was also more abundant in high tunnels in 2010. Cucumber beetle (striped (Acalymma vittatum F.) and spotted (Diabrotica undecimpunctata Mannerheim)) densities were higher in high tunnels in 2010 and field plots in 2011. The common assumption that high tunnels offer protection from field pests was not supported. Instead, high tunnel growing conditions may facilitate higher pest populations. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Effects of load-bearing exercise on skeletal structure and mechanics differ between outbred populations of mice.

PubMed

Wallace, Ian J; Judex, Stefan; Demes, Brigitte

2015-03-01

Effects of load-bearing exercise on skeletal structure and mechanical properties can vary between inbred strains of mice. Here, we examine whether such variation also exists at the population level. An experiment was performed with two outbred mouse stocks that have been reproductively isolated for >120 generations (Hsd:ICR, Crl:CD1). Growing females from each stock were either treated with a treadmill-running regimen for 1 month or served as controls. Limb forces were recorded with a force plate and cage activity monitored to verify that they were similar between stocks. After the experiment, femoral cortical and trabecular bone structure were quantified with micro-CT in the mid-diaphysis and distal metaphysis, respectively, and diaphyseal structural strength was determined with mechanical testing. Among Hsd:ICR mice, running led to significant improvements in diaphyseal bone quantity, structural geometry, and mechanical properties, as well as enhanced trabecular morphology. In contrast, among Crl:CD1 mice, the same running regimen had little effect on cortical and trabecular structure and significantly reduced diaphyseal resistance to fracture. In neither stock was body mass, muscle mass, or cage activity level different between runners and controls. Given that most environmental variables were controlled in this study, the differential effects of exercise on Hsd:ICR and Crl:CD1 bones were likely due to genetic differences between stocks. These results suggest that the benefits of loading for bone may vary between human populations (e.g., ethnic groups), in which case exercise programs and technologies designed to promote bone health with mechanical signals may be more advantageous to certain populations than others. Copyright © 2014 Elsevier Inc. All rights reserved.

Active bacterial community structure along vertical redox gradients in Baltic Sea sediment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jansson, Janet; Edlund, Anna; Hardeman, Fredrik

Community structures of active bacterial populations were investigated along a vertical redox profile in coastal Baltic Sea sediments by terminal-restriction fragment length polymorphism (T-RFLP) and clone library analysis. According to correspondence analysis of T-RFLP results and sequencing of cloned 16S rRNA genes, the microbial community structures at three redox depths (179 mV, -64 mV and -337 mV) differed significantly. The bacterial communities in the community DNA differed from those in bromodeoxyuridine (BrdU)-labeled DNA, indicating that the growing members of the community that incorporated BrdU were not necessarily the most dominant members. The structures of the actively growing bacterial communities weremore » most strongly correlated to organic carbon followed by total nitrogen and redox potentials. Bacterial identification by sequencing of 16S rRNA genes from clones of BrdU-labeled DNA and DNA from reverse transcription PCR (rt-PCR) showed that bacterial taxa involved in nitrogen and sulfur cycling were metabolically active along the redox profiles. Several sequences had low similarities to previously detected sequences indicating that novel lineages of bacteria are present in Baltic Sea sediments. Also, a high number of different 16S rRNA gene sequences representing different phyla were detected at all sampling depths.« less

Jedi Public Health: Co-creating an Identity-Safe Culture to Promote Health Equity.

PubMed

Geronimus, Arline T; James, Sherman A; Destin, Mesmin; Graham, Louis A; Hatzenbuehler, Mark; Murphy, Mary; Pearson, Jay A; Omari, Amel; Thompson, James Phillip

2016-12-01

The extent to which socially-assigned and culturally mediated social identity affects health depends on contingencies of social identity that vary across and within populations in day-to-day life. These contingencies are structurally rooted and health damaging inasmuch as they activate physiological stress responses. They also have adverse effects on cognition and emotion, undermining self-confidence and diminishing academic performance. This impact reduces opportunities for social mobility, while ensuring those who "beat the odds" pay a physical price for their positive efforts. Recent applications of social identity theory toward closing racial, ethnic, and gender academic achievement gaps through changing features of educational settings, rather than individual students, have proved fruitful. We sought to integrate this evidence with growing social epidemiological evidence that structurally-rooted biopsychosocial processes have population health effects. We explicate an emergent framework, Jedi Public Health (JPH). JPH focuses on changing features of settings in everyday life, rather than individuals, to promote population health equity, a high priority, yet, elusive national public health objective. We call for an expansion and, in some ways, a re-orienting of efforts to eliminate population health inequity. Policies and interventions to remove and replace discrediting cues in everyday settings hold promise for disrupting the repeated physiological stress process activation that fuels population health inequities with potentially wide application.

Highly polygenic variation in environmental perception determines dauer larvae formation in growing populations of Caenorhabditis elegans.

PubMed

Green, James W M; Stastna, Jana J; Orbidans, Helen E; Harvey, Simon C

2014-01-01

Determining how complex traits are genetically controlled is a requirement if we are to predict how they evolve and how they might respond to selection. This requires understanding how distinct, and often more simple, life history traits interact and change in response to environmental conditions. In order to begin addressing such issues, we have been analyzing the formation of the developmentally arrested dauer larvae of Caenorhabditis elegans under different conditions. We find that 18 of 22 previously identified quantitative trait loci (QTLs) affecting dauer larvae formation in growing populations, assayed by determining the number of dauer larvae present at food patch exhaustion, can be recovered under various environmental conditions. We also show that food patch size affects both the ability to detect QTLs and estimates of effect size, and demonstrate that an allele of nath-10 affects dauer larvae formation in growing populations. To investigate the component traits that affect dauer larvae formation in growing populations we map, using the same introgression lines, QTLs that affect dauer larvae formation in response to defined amounts of pheromone. This identifies 36 QTLs, again demonstrating the highly polygenic nature of the genetic variation underlying dauer larvae formation. These data indicate that QTLs affecting the number of dauer larvae at food exhaustion in growing populations of C. elegans are highly reproducible, and that nearly all can be explained by variation affecting dauer larvae formation in response to defined amounts of pheromone. This suggests that most variation in dauer larvae formation in growing populations is a consequence of variation in the perception of the food and pheromone environment (i.e. chemosensory variation) and in the integration of these cues.

Adaptations in bacterial catabolic enzyme activity and community structure in membrane-coupled bioreactors fed simple synthetic wastewater.

PubMed

LaPara, Timothy M; Klatt, Christian G; Chen, Ruoyu

2006-02-10

Membrane-coupled bioreactors (MBRs) offer substantial benefits compared to conventional reactor designs for biological wastewater treatment. MBR treatment efficiency, however, has not been optimized because the effects of the MBR on process microbiology are poorly understood. In this study, the structure and function of the microbial communities growing in MBRs fed simple synthetic wastewater were investigated. In four starch-fed MBRs, the bacterial community substantially increased its alpha-glucosidase affinity (>1000-fold), while the leucine aminopeptidase and heptanoate esterase affinities increased slightly (<40-fold) or remained relatively constant. Concomitant to these physiological adaptations, shifts in the bacterial community structure in two of the starch-fed MBRs were detected by PCR-DGGE. Four of the bacterial populations detected by PCR-DGGE were isolated and exhibited specific growth rates in batch culture ranging from 0.009 to 0.22 h(-1). Our results suggest that bacterial communities growing under increasingly stringent nutrient limitation adapt their enzyme activities primarily for the nutrients provided, but that there is also a more subtle response not linked to the substrates included in the feed medium. Our research also demonstrates that MBRs can support relatively complex bacterial communities even on simple feed media.

What's in a name? Y chromosomes, surnames and the genetic genealogy revolution.

PubMed

King, Turi E; Jobling, Mark A

2009-08-01

Heritable surnames are highly diverse cultural markers of coancestry in human populations. A patrilineal surname is inherited in the same way as the non-recombining region of the Y chromosome and there should, therefore, be a correlation between the two. Studies of Y haplotypes within surnames, mostly of the British Isles, reveal high levels of coancestry among surname cohorts and the influence of confounding factors, including multiple founders for names, non-paternities and genetic drift. Combining molecular genetics and surname analysis illuminates population structure and history, has potential applications in forensic studies and, in the form of 'genetic genealogy', is an area of rapidly growing interest for the public.

New Coumarinyl Ethers in Daphne oleoides Schreb. Collected from Sardinia Island.

PubMed

Venditti, Alessandro; Sanna, Cinzia; Lorenzetti, Lorenzo M; Ballero, Mauro; Bianco, Armandodoriano

2017-06-01

The phytochemical analysis of the ethanolic extract obtained from D. oleoides collected from Sardinia Island allowed the isolation of several new constituents for the species (3, 8, and 9) together with two new coumarinyl ethers (1 and 2) besides the chemotaxonomic markers of the Daphne genus (4 - 7 and 10) which are also known to possess interesting biological activities. The structure of the new compounds were elucidated by extensive spectroscopic and spectrometric analyses. The identification of these compounds gives an experimental evidence of the variability in the secondary metabolites pattern owned by populations growing in restricted area in respect to populations not confined by geographical barrier. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

Elephant behaviour and conservation: social relationships, the effects of poaching, and genetic tools for management.

PubMed

Archie, Elizabeth A; Chiyo, Patrick I

2012-02-01

Genetic tools are increasingly valuable for understanding the behaviour, evolution, and conservation of social species. In African elephants, for instance, genetic data provide basic information on the population genetic causes and consequences of social behaviour, and how human activities alter elephants' social and genetic structures. As such, African elephants provide a useful case study to understand the relationships between social behaviour and population genetic structure in a conservation framework. Here, we review three areas where genetic methods have made important contributions to elephant behavioural ecology and conservation: (1) understanding kin-based relationships in females and the effects of poaching on the adaptive value of elephant relationships, (2) understanding patterns of paternity in elephants and how poaching can alter these patterns, and (3) conservation genetic tools to census elusive populations, track ivory, and understand the behavioural ecology of crop-raiding. By comparing studies from populations that have experienced a range of poaching intensities, we find that human activities have a large effect on elephant behaviour and genetic structure. Poaching disrupts kin-based association patterns, decreases the quality of elephant social relationships, and increases male reproductive skew, with important consequences for population health and the maintenance of genetic diversity. In addition, we find that genetic tools to census populations or gather forensic information are almost always more accurate than non-genetic alternatives. These results contribute to a growing understanding of poaching on animal behaviour, and how genetic tools can be used to understand and conserve social species. © 2011 Blackwell Publishing Ltd.

Genetic mapping of variation in dauer larvae development in growing populations of Caenorhabditis elegans.

PubMed

Green, J W M; Snoek, L B; Kammenga, J E; Harvey, S C

2013-10-01

In the nematode Caenorhabditis elegans, the appropriate induction of dauer larvae development within growing populations is likely to be a primary determinant of genotypic fitness. The underlying genetic architecture of natural genetic variation in dauer formation has, however, not been thoroughly investigated. Here, we report extensive natural genetic variation in dauer larvae development within growing populations across multiple wild isolates. Moreover, bin mapping of introgression lines (ILs) derived from the genetically divergent isolates N2 and CB4856 reveals 10 quantitative trait loci (QTLs) affecting dauer formation. Comparison of individual ILs to N2 identifies an additional eight QTLs, and sequential IL analysis reveals six more QTLs. Our results also show that a behavioural, laboratory-derived, mutation controlled by the neuropeptide Y receptor homolog npr-1 can affect dauer larvae development in growing populations. These findings illustrate the complex genetic architecture of variation in dauer larvae formation in C. elegans and may help to understand how the control of variation in dauer larvae development has evolved.

Optimal control of Atlantic population Canada geese

USGS Publications Warehouse

Hauser, C.E.; Runge, M.C.; Cooch, E.G.; Johnson, F.A.; Harvey, W.F.

2007-01-01

Management of Canada geese (Branta canadensis) can be a balance between providing sustained harvest opportunity while not allowing populations to become overabundant and cause damage. In this paper, we focus on the Atlantic population of Canada geese and use stochastic dynamic programming to determine the optimal harvest strategy over a range of plausible models for population dynamics. There is evidence to suggest that the population exhibits significant age structure, and it is possible to reconstruct age structure from surveys. Consequently the harvest strategy is a function of the age composition, as well as the abundance, of the population. The objective is to maximize harvest while maintaining the number of breeding adults in the population between specified upper and lower limits. In addition, the total harvest capacity is limited and there is uncertainty about the strength of density-dependence. We find that under a density-independent model, harvest is maximized by maintaining the breeding population at the highest acceptable abundance. However if harvest capacity is limited, then the optimal long-term breeding population size is lower than the highest acceptable level, to reduce the risk of the population growing to an unacceptably large size. Under the proposed density-dependent model, harvest is maximized by maintaining the breeding population at an intermediate level between the bounds on acceptable population size; limits to harvest capacity have little effect on the optimal long-term population size. It is clear that the strength of density-dependence and constraints on harvest significantly affect the optimal harvest strategy for this population. Model discrimination might be achieved in the long term, while continuing to meet management goals, by adopting an adaptive management strategy.

Suppression of invasive lake trout in an isolated backcountry lake in Glacier National Park

USGS Publications Warehouse

Fredenberg, C. R.; Muhlfeld, Clint C.; Guy, Christopher S.; D'Angelo, Vincent S.; Downs, Christopher C.; Syslo, John M.

2017-01-01

Fisheries managers have implemented suppression programmes to control non-native lake trout, Salvelinus namaycush (Walbaum), in several lakes throughout the western United States. This study determined the feasibility of experimentally suppressing lake trout using gillnets in an isolated backcountry lake in Glacier National Park, Montana, USA, for the conservation of threatened bull trout, Salvelinus confluentus (Suckley). The demographics of the lake trout population during suppression (2009–2013) were described, and those data were used to assess the effects of suppression scenarios on population growth rate (λ) using an age-structured population model. Model simulations indicated that the population was growing exponentially (λ = 1.23, 95% CI: 1.16–1.28) prior to suppression. However, suppression resulted in declining λ(0.61–0.79) for lake trout, which was concomitant with stable bull trout adult abundances. Continued suppression at or above observed exploitation levels is needed to ensure continued population declines.

[Genetic variation of some varieties of common juniper Juniperus communis L. inferred from analysis of allozyme loci].

PubMed

Khantemirova, E V; Semerikov, V L

2010-05-01

Using the method of allozyme analysis, genetic variation, diversity, and population structure of Juniperus communis L. var. communis and J. communis L. var. saxatilis Pall. (= J. sibirica Burgsd. = J. nana Wild), growing on the territory of Russia, J. c. var. communis from Sweden, and J. c. var. depressa Pursh from Northern America (Alaska), was investigated. The total level of genetic variation of these varieties was found to be higher than the values obtained for the other conifers. The population samples of J. c. var. depressa from Alaska and J. c. var. saxatilis from Sakhalin were noticeably different from all other populations examined. Between the other samples, no substantial genetic differences were observed. These populations were characterized by weak interpopulation differentiation along with the absence of expressed geographical pattern of the allele frequency spatial distribution. The only exception was the procumbent form of common juniper from the high mountain populations of South and North Ural, which was somewhat different from the others.

Population genetic analysis and trichothecene profiling of Fusarium graminearum from wheat in Uruguay.

PubMed

Pan, D; Mionetto, A; Calero, N; Reynoso, M M; Torres, A; Bettucci, L

2016-03-11

Fusarium graminearum sensu stricto (F. graminearum s.s.) is the major causal agent of Fusarium head blight of wheat worldwide, and contaminates grains with trichothecene mycotoxins that cause serious threats to food safety and animal health. An important aspect of managing this pathogen and reducing mycotoxin contamination of wheat is knowledge regarding its population genetics. Therefore, isolates of F. graminearum s.s. from the major wheat-growing region of Uruguay were analyzed by amplified fragment length polymorphism assays, PCR genotyping, and chemical analysis of trichothecene production. Of the 102 isolates identified as having the 15-ADON genotype via PCR genotyping, all were DON producers, but only 41 strains were also 15-ADON producers, as determined by chemical analysis. The populations were genotypically diverse but genetically similar, with significant genetic exchange occurring between them. Analysis of molecular variance indicated that most of the genetic variability resulted from differences between isolates within populations. Multilocus linkage disequilibrium analysis suggested that the isolates had a panmictic population genetic structure and that there is significant recombination occurs in F. graminearum s.s. In conclusion, tour findings provide the first detailed description of the genetic structure and trichothecene production of populations of F. graminearum s.s. from Uruguay, and expands our understanding of the agroecology of F. graminearum and of the correlation between genotypes and trichothecene chemotypes.

Making sense of snapshot data: ergodic principle for clonal cell populations

PubMed Central

2017-01-01

Population growth is often ignored when quantifying gene expression levels across clonal cell populations. We develop a framework for obtaining the molecule number distributions in an exponentially growing cell population taking into account its age structure. In the presence of generation time variability, the average acquired across a population snapshot does not obey the average of a dividing cell over time, apparently contradicting ergodicity between single cells and the population. Instead, we show that the variation observed across snapshots with known cell age is captured by cell histories, a single-cell measure obtained from tracking an arbitrary cell of the population back to the ancestor from which it originated. The correspondence between cells of known age in a population with their histories represents an ergodic principle that provides a new interpretation of population snapshot data. We illustrate the principle using analytical solutions of stochastic gene expression models in cell populations with arbitrary generation time distributions. We further elucidate that the principle breaks down for biochemical reactions that are under selection, such as the expression of genes conveying antibiotic resistance, which gives rise to an experimental criterion with which to probe selection on gene expression fluctuations. PMID:29187636

Making sense of snapshot data: ergodic principle for clonal cell populations.

PubMed

Thomas, Philipp

2017-11-01

Population growth is often ignored when quantifying gene expression levels across clonal cell populations. We develop a framework for obtaining the molecule number distributions in an exponentially growing cell population taking into account its age structure. In the presence of generation time variability, the average acquired across a population snapshot does not obey the average of a dividing cell over time, apparently contradicting ergodicity between single cells and the population. Instead, we show that the variation observed across snapshots with known cell age is captured by cell histories, a single-cell measure obtained from tracking an arbitrary cell of the population back to the ancestor from which it originated. The correspondence between cells of known age in a population with their histories represents an ergodic principle that provides a new interpretation of population snapshot data. We illustrate the principle using analytical solutions of stochastic gene expression models in cell populations with arbitrary generation time distributions. We further elucidate that the principle breaks down for biochemical reactions that are under selection, such as the expression of genes conveying antibiotic resistance, which gives rise to an experimental criterion with which to probe selection on gene expression fluctuations. © 2017 The Author(s).

Origins and Divergence of the Roma (Gypsies)

PubMed Central

Gresham, David; Morar, Bharti; Underhill, Peter A.; Passarino, Giuseppe; Lin, Alice A.; Wise, Cheryl; Angelicheva, Dora; Calafell, Francesc; Oefner, Peter J.; Shen, Peidong; Tournev, Ivailo; de Pablo, Rosario; Kuĉinskas, Vaidutis; Perez-Lezaun, Anna; Marushiakova, Elena; Popov, Vesselin; Kalaydjieva, Luba

2001-01-01

The identification of a growing number of novel Mendelian disorders and private mutations in the Roma (Gypsies) points to their unique genetic heritage. Linguistic evidence suggests that they are of diverse Indian origins. Their social structure within Europe resembles that of the jatis of India, where the endogamous group, often defined by profession, is the primary unit. Genetic studies have reported dramatic differences in the frequencies of mutations and neutral polymorphisms in different Romani populations. However, these studies have not resolved ambiguities regarding the origins and relatedness of Romani populations. In this study, we examine the genetic structure of 14 well-defined Romani populations. Y-chromosome and mtDNA markers of different mutability were analyzed in a total of 275 individuals. Asian Y-chromosome haplogroup VI-68, defined by a mutation at the M82 locus, was present in all 14 populations and accounted for 44.8% of Romani Y chromosomes. Asian mtDNA-haplogroup M was also identified in all Romani populations and accounted for 26.5% of female lineages in the sample. Limited diversity within these two haplogroups, measured by the variation at eight short-tandem-repeat loci for the Y chromosome, and sequencing of the HVS1 for the mtDNA are consistent with a small group of founders splitting from a single ethnic population in the Indian subcontinent. Principal-components analysis and analysis of molecular variance indicate that genetic structure in extant endogamous Romani populations has been shaped by genetic drift and differential admixture and correlates with the migrational history of the Roma in Europe. By contrast, social organization and professional group divisions appear to be the product of a more recent restitution of the caste system of India. PMID:11704928

Origins and divergence of the Roma (gypsies).

PubMed

Gresham, D; Morar, B; Underhill, P A; Passarino, G; Lin, A A; Wise, C; Angelicheva, D; Calafell, F; Oefner, P J; Shen, P; Tournev, I; de Pablo, R; Kuĉinskas, V; Perez-Lezaun, A; Marushiakova, E; Popov, V; Kalaydjieva, L

2001-12-01

The identification of a growing number of novel Mendelian disorders and private mutations in the Roma (Gypsies) points to their unique genetic heritage. Linguistic evidence suggests that they are of diverse Indian origins. Their social structure within Europe resembles that of the jatis of India, where the endogamous group, often defined by profession, is the primary unit. Genetic studies have reported dramatic differences in the frequencies of mutations and neutral polymorphisms in different Romani populations. However, these studies have not resolved ambiguities regarding the origins and relatedness of Romani populations. In this study, we examine the genetic structure of 14 well-defined Romani populations. Y-chromosome and mtDNA markers of different mutability were analyzed in a total of 275 individuals. Asian Y-chromosome haplogroup VI-68, defined by a mutation at the M82 locus, was present in all 14 populations and accounted for 44.8% of Romani Y chromosomes. Asian mtDNA-haplogroup M was also identified in all Romani populations and accounted for 26.5% of female lineages in the sample. Limited diversity within these two haplogroups, measured by the variation at eight short-tandem-repeat loci for the Y chromosome, and sequencing of the HVS1 for the mtDNA are consistent with a small group of founders splitting from a single ethnic population in the Indian subcontinent. Principal-components analysis and analysis of molecular variance indicate that genetic structure in extant endogamous Romani populations has been shaped by genetic drift and differential admixture and correlates with the migrational history of the Roma in Europe. By contrast, social organization and professional group divisions appear to be the product of a more recent restitution of the caste system of India.

Growing rod erosion through the lamina causing spinal cord compression in an 8-year-old girl with early-onset scoliosis.

PubMed

Abduljabbar, Fahad H; Waly, Feras; Nooh, Anas; Ouellet, Jean

2016-09-01

Early-onset scoliosis often occurs by the age of 5 years and is attributed to many structural abnormalities. Syndromic early-onset scoliosis is considered one of the most aggressive types of early-onset scoliosis. Treatment starts with serial casting and bracing, but eventually most of these patients undergo growth-sparing procedures, such as a single growing rod, dual growing rods, or a vertical expandable titanium prosthetic rib. This case report aimed to describe an unusual complication of erosion of a growing rod through the lamina that caused spinal cord compression in an 8-year-old girl with early-onset scoliosis. This is a case report. A retrospective chart review was used to describe the clinical course and radiographic findings of this case after rod erosion into the spinal canal. The patient underwent successful revision surgery removing the rod without neurologic complications. Patients with syndromic early-onset scoliosis are more prone to progressive curves and severe rotational deformity. We believe that the severe kyphotic deformity in addition to the dysplastic nature of the deformity in this population may predispose them to this unusual complication. Copyright © 2016 Elsevier Inc. All rights reserved.

A Demographic Analysis of American Geophysical Union Membership with Implications for Change

NASA Astrophysics Data System (ADS)

Rhodes, D. D.

2006-12-01

Demographers use population pyramids to characterize the age/gender structure of societal groups. Diagrams of the population of age cohorts for both sexes assume the shape of a pyramid in rapidly expanding groups, having many more young people than older adults. Stable populations have similar numbers of people in age cohorts from infants through middle-age adults. Shrinking populations have fewer children and relatively larger numbers of adults. Demographic analysis of the American Geophysical Union's (AGU) membership reveals significant differences among the numerous specialties and the membership as a whole. The population structure diagram of the total AGU membership is highly asymmetrical with 77.5% male and 22.5% female. Males outnumber females in every age cohort. This is most noticeable among members born prior to 1945. Males belonging to these cohorts make up 16.5% of the total membership, while female members of equivalent age include 0.8% of the total. The largest membership cohort (29% of the total) is comprised of males born between 1950 and 1964, a group that includes both the "baby boom" generation and post-war petroleum exploration expansion. In contrast, the female cohort with birth years from 1970 to 1979 is the largest grouping of women members (8.4% of AGU's membership). Furthermore, women comprise 36% of the members born since 1965, and only 14.5% of those born before 1965. Considered separately, the female membership's age structure is characteristic of a growing population, while the male side is in relative decline. The population structure of the entire membership is mirrored in some specialties, but there are remarkable differences in others. The largest specialty group (hydrology) includes 16.9% of the total AGU membership and has a population structure that differs little from that of the whole organization. Four specialties, Atmospheric Chemistry, Biogeosciences, and Paleoceanography and Paleoclimatology, and Marine Geochemistry differ significantly from the aggregate membership. The population structures of these groups are pyramidal, indicating a strong potential for growth. Women also comprise more than 30% of each of these groups and outnumber men in some recent cohorts. Growth potential is unevenly distributed throughout AGU's membership with traditional specialties likely to experience significant decline as the older cohorts retire and die. Strongest growth is most likely to occur in recently recognized interdisciplinary specialties, especially those in which women already constitute a significant fraction of the membership.

New activities at the U.S. Geological Survey

USGS Publications Warehouse

McKelvey, Vincent E.

1974-01-01

As the Nation's principal source of information about the configuration of the land surface, the composition and structure of the rocks at and beneath the surface, the distribution and character of its energy, mineral, and water resources, and the nature of natural geologic processes, the U. S. Geological Survey focuses its work on some of the Nation's most critical problems. As the Survey tackles new problems with new techniques, it is fully aware of the resource needs and environmental pressures of an expanding economy and growing population.

Survival and metamorphosis of low-density populations of larval sea lampreys (Petromyzon marinus) in streams following lampricide treatment

USGS Publications Warehouse

Johnson, Nicholas S.; Swink, William D.; Brenden, Travis O.; Slade, Jeffrey W.; Steeves, Todd B.; Fodale, Michael F.; Jones, Michael L.

2014-01-01

Sea lamprey Petromyzon marinus control in the Great Lakes primarily involves application of lampricides to streams where larval production occurs to kill larvae prior to their metamorphosing and entering the lakes as parasites (juveniles). Because lampricides are not 100% effective, larvae that survive treatment maymetamorphose before streams are again treated. Larvae that survive treatment have not beenwidely studied, so their dynamics are notwell understood.Wetagged and released larvae in six Great Lake tributaries following lampricide treatment and estimated vital demographic rates using multistate tag-recovery models. Model-averaged larval survivals ranged from 56.8 to 57.6%. Model-averaged adult recovery rates, which were the product of juvenile survivals and adult capture probabilities, ranged from 6.8 to 9.3%. Using stochastic simulations, we estimated production of juvenile sea lampreys from a hypothetical population of treatment survivors under different growth conditions based on parameter estimates from this research. For fast-growing populations, juvenile production peaked 2 years after treatment. For slow-growing populations, juvenile production was approximately one-third that of fast-growing populations,with production not peaking until 4 years after treatment. Our results suggest that dynamics (i.e., survival, metamorphosis) of residual larval populations are very similar to those of untreated larval populations. Consequently, residual populations do not necessarily warrant special consideration for the purpose of sea lamprey control and can be ranked for treatment along with other populations. Consecutive lampricide treatments, which are under evaluation by the sea lamprey control program, would bemost effective for reducing juvenile production in large, fast-growing populations.

Dynamics of ambulatory surgery centers and hospitals market entry.

PubMed

Housman, Michael; Al-Amin, Mona

2013-08-01

In this article, we investigate the diversity of healthcare delivery organizations by comparing the market determinants of hospitals entry rates with those of ambulatory surgery centers (ASCs). Unlike hospitals, ASCs is one of the growing populations of specialized healthcare delivery organizations. There are reasons to believe that firm entry patterns differ within growing organizational populations since these markets are characterized by different levels of organizational legitimacy, technological uncertainty, and information asymmetry. We compare the entry patterns of firms in a mature population of hospitals to those of firms within a growing population of ASCs. By using patient-level datasets from the state of Florida, we break down our explanatory variables by facility type (ASC vs. hospital) and utilize negative binomial regression models to evaluate the impact of niche density on ASC and hospital entry. Our results indicate that ASCs entry rates is higher in markets with overlapping ASCs while hospitals entry rates are less in markets with overlapping hospitals and ASCs. These results are consistent with the notion that firms in growing populations tend to seek out crowded markets as they compete to occupy the most desirable market segments while firms in mature populations such as general hospitals avoid direct competition. © The Author(s) 2013 Reprints and permissions:]br]sagepub.co.uk/journalsPermissions.nav.

A change in climate causes rapid evolution of multiple life-history traits and their interactions in an annual plant.

PubMed

Franks, S J; Weis, A E

2008-09-01

Climate change is likely to spur rapid evolution, potentially altering integrated suites of life-history traits. We examined evolutionary change in multiple life-history traits of the annual plant Brassica rapa collected before and after a recent 5-year drought in southern California. We used a direct approach to examining evolutionary change by comparing ancestors and descendants. Collections were made from two populations varying in average soil moisture levels, and lines propagated from the collected seeds were grown in a greenhouse and experimentally subjected to conditions simulating either drought (short growing season) or high precipitation (long growing season) years. Comparing ancestors and descendants, we found that the drought caused many changes in life-history traits, including a shift to earlier flowering, longer duration of flowering, reduced peak flowering and greater skew of the flowering schedule. Descendants had thinner stems and fewer leaf nodes at the time of flowering than ancestors, indicating that the drought selected for plants that flowered at a smaller size and earlier ontogenetic stage rather than selecting for plants to develop more rapidly. Thus, there was not evidence for absolute developmental constraints to flowering time evolution. Common principal component analyses showed substantial differences in the matrix of trait covariances both between short and long growing season treatments and between populations. Although the covariances matrices were generally similar between ancestors and descendants, there was evidence for complex evolutionary changes in the relationships among the traits, and these changes depended on the population and treatment. These results show that a full appreciation of the impacts of global change on phenotypic evolution will entail an understanding of how changes in climatic conditions affect trait values and the structure of relationships among traits.

Enhancing Geriatric Curriculum in Nursing School

ERIC Educational Resources Information Center

Collins, Kevin

2013-01-01

People are living longer. The average age of the population is increasing, and is expected to keep growing. Any person age 65 and older is now considered "geriatric." However, although growing, this population is not receiving adequate nursing care, and results in increased pain, falls, and even death. Geriatric curriculum is becoming…

System-Level Shared Governance Structures and Processes in Healthcare Systems With Magnet®-Designated Hospitals: A Descriptive Study.

PubMed

Underwood, Carlisa M; Hayne, Arlene N

The purpose was to identify and describe structures and processes of best practices for system-level shared governance in healthcare systems. Currently, more than 64.6% of US community hospitals are part of a system. System chief nurse executives (SCNEs) are challenged to establish leadership structures and processes that effectively and efficiently disseminate best practices for patients and staff across complex organizations, geographically dispersed locations, and populations. Eleven US healthcare SCNEs from the American Nurses Credentialing Center's repository of Magnet®-designated facilities participated in a 35-multiquestion interview based on Kanter's Theory of Organizational Empowerment. Most SCNEs reported the presence of more than 50% of the empowerment structures and processes in system-level shared governance. Despite the difficulties and complexities of growing health systems, SCNEs have replicated empowerment characteristics of hospital shared governance structures and processes at the system level.

Structural stigma, sex work and HIV: contradictions and lessons learnt from a community-led structural intervention in southern India.

PubMed

Biradavolu, Monica Rao; Blankenship, Kim M; Jena, Asima; Dhungana, Nimesh

2012-10-01

Recent theorisation has pushed stigma research in new directions, arguing for a need to challenge the unequal power relations that impact groups most at risk for HIV-related stigma rather than locate stigma in the individual. Such a conceptualisation resonates with the growing emphasis on structural interventions for HIV prevention that attempt to alter the social context of risk. The paper predominantly relies on longitudinal interviews conducted three times over a 2-year period with sex workers with varying degrees of involvement with the non-governmental organisation (NGO) and community-based organisation. Recognising that stigma is socially constructed and structurally reproduced, the NGO helped mobilise marginalised and hitherto scattered female sex workers to form community-based organisations to challenge their disadvantaged status in society. The authors show how stigma alleviation strategies presented a contradiction: emboldening one group of female sex workers to self-identify as sex workers while making others reluctant to access the intervention-run clinic. The paper builds on a growing body of research that acknowledges the struggles in implementing structural interventions, particularly for NGOs working in regions with a diverse population of sex workers with varying needs. The authors argue that intervention goals of reducing stigma and increasing the use of sexually transmitted infection services do not have to conflict and, in fact, must go hand-in-hand for an implementation to be considered a structural intervention.

Essential oil variation among natural populations of Lavandula multifida L. (Lamiaceae).

PubMed

Chograni, Hnia; Zaouali, Yosr; Rajeb, Chayma; Boussaid, Mohamed

2010-04-01

Volatiles from twelve wild Tunisian populations of Lavandula multifida L. growing in different bioclimatic zones were assessed by GC (RI) and GC/MS. Thirty-six constituents, representing 83.48% of the total oil were identified. The major components at the species level were carvacrol (31.81%), beta-bisabolene (14.89%), and acrylic acid dodecyl ester (11.43%). These volatiles, together with alpha-pinene, were also the main compounds discriminating the populations. According to these dominant compounds, one chemotype was revealed, a carvacrol/beta-bisabolene/acrylic acid dodecyl ester chemotype. However, a significant variation among the populations was observed for the majority of the constituents. A high chemical-population structure, estimated both by principal component analysis (PCA) and unweighted pair group method with averaging (UPGMA) cluster analysis based on Euclidean distances, was observed. Both methods allowed separation of the populations in three groups defined rather by minor than by major compounds. The population groups were not strictly concordant with their bioclimatic or geographic location. Conservation strategies should concern all populations, because of their low size and their high level of destruction. Populations exhibiting particular compounds other than the major ones should be protected first.

Family Structure Transitions and Child Development: Instability, Selection, and Population Heterogeneity.

PubMed

Lee, Dohoon; McLanahan, Sara

2015-08-01

A growing literature documents the importance of family instability for child wellbeing. In this article, we use longitudinal data from the Fragile Families and Child Wellbeing Study to examine the impacts of family instability on children's cognitive and socioemotional development in early and middle childhood. We extend existing research in several ways: (1) by distinguishing between the number and types of family structure changes; (2) by accounting for time-varying as well as time-constant confounding; and (3) by assessing racial/ethnic and gender differences in family instability effects. Our results indicate that family instability has a causal effect on children's development, but the effect depends on the type of change, the outcome assessed, and the population examined. Generally speaking, transitions out of a two-parent family are more negative for children's development than transitions into a two-parent family. The effect of family instability is stronger for children's socioemotional development than for their cognitive achievement. For socioemotional development, transitions out of a two-parent family are more negative for white children, whereas transitions into a two-parent family are more negative for Hispanic children. These findings suggest that future research should pay more attention to the type of family structure transition and to population heterogeneity.

Family Structure Transitions and Child Development: Instability, Selection, and Population Heterogeneity

PubMed Central

Lee, Dohoon; McLanahan, Sara

2016-01-01

A growing literature documents the importance of family instability for child wellbeing. In this article, we use longitudinal data from the Fragile Families and Child Wellbeing Study to examine the impacts of family instability on children’s cognitive and socioemotional development in early and middle childhood. We extend existing research in several ways: (1) by distinguishing between the number and types of family structure changes; (2) by accounting for time-varying as well as time-constant confounding; and (3) by assessing racial/ethnic and gender differences in family instability effects. Our results indicate that family instability has a causal effect on children’s development, but the effect depends on the type of change, the outcome assessed, and the population examined. Generally speaking, transitions out of a two-parent family are more negative for children’s development than transitions into a two-parent family. The effect of family instability is stronger for children’s socioemotional development than for their cognitive achievement. For socioemotional development, transitions out of a two-parent family are more negative for white children, whereas transitions into a two-parent family are more negative for Hispanic children. These findings suggest that future research should pay more attention to the type of family structure transition and to population heterogeneity. PMID:27293242

Effects of prescribed fire on vegetation and passerine birds in northern mixed-grass prairie

USGS Publications Warehouse

Grant, T.A.; Madden, E.M.; Shaffer, T.L.; Dockens, J.S.

2010-01-01

Prescribed fire is used widely to manage grasslands on National Wildlife Refuges and other public lands in the northern Great Plains, but its effects on habitat use or production of wildlife in the region are poorly understood. During 19982003, we used point counts to examine effects of prescribed fire on vegetation and passerines in a mixed-grass prairie complex in north-central North Dakota, USA (n 7 units, each 4070 ha). Vegetation structure and, to a lesser extent, plant community composition varied with year of study (likely related to changes in annual precipitation) and with number of growing seasons since fire. Fire altered plant structure, especially the amount of residual vegetation, which in turn influenced bird species richness and abundance. The number of indicated pairs for sedge wren (Cistothorus platensis), clay-colored sparrow (Spizella pallida), Le Conte's sparrow (Ammodramus leconteii), Savannah sparrow (Passerculus sandwichensis), and bobolink (Dolichonyx oryzivorus) were lowest during the first postfire growing season but generally increased and stabilized within 23 postfire growing seasons. Our results support the premise that grassland passerines are well-adapted to frequent, periodic fires, generally corresponding to those occurring prior to EuroAmerican settlement of the region. Prescribed fire is important for reducing tree and shrub invasion, restoring biological integrity of plant communities, and maintaining or enhancing populations of grassland-dependent bird species. Managers in the northern mixed-grass prairie region should not be overly concerned about reductions in bird abundances that are limited mostly to the first growing season after fire. 2010 The Wildlife Society.

Population Fluctuation Promotes Cooperation in Networks

PubMed Central

Miller, Steve; Knowles, Joshua

2015-01-01

We consider the problem of explaining the emergence and evolution of cooperation in dynamic network-structured populations. Building on seminal work by Poncela et al., which shows how cooperation (in one-shot prisoner’s dilemma) is supported in growing populations by an evolutionary preferential attachment (EPA) model, we investigate the effect of fluctuations in the population size. We find that a fluctuating model – based on repeated population growth and truncation – is more robust than Poncela et al.’s in that cooperation flourishes for a wider variety of initial conditions. In terms of both the temptation to defect, and the types of strategies present in the founder network, the fluctuating population is found to lead more securely to cooperation. Further, we find that this model will also support the emergence of cooperation from pre-existing non-cooperative random networks. This model, like Poncela et al.’s, does not require agents to have memory, recognition of other agents, or other cognitive abilities, and so may suggest a more general explanation of the emergence of cooperation in early evolutionary transitions, than mechanisms such as kin selection, direct and indirect reciprocity. PMID:26061705

Estimating mutation parameters, population history and genealogy simultaneously from temporally spaced sequence data.

PubMed Central

Drummond, Alexei J; Nicholls, Geoff K; Rodrigo, Allen G; Solomon, Wiremu

2002-01-01

Molecular sequences obtained at different sampling times from populations of rapidly evolving pathogens and from ancient subfossil and fossil sources are increasingly available with modern sequencing technology. Here, we present a Bayesian statistical inference approach to the joint estimation of mutation rate and population size that incorporates the uncertainty in the genealogy of such temporally spaced sequences by using Markov chain Monte Carlo (MCMC) integration. The Kingman coalescent model is used to describe the time structure of the ancestral tree. We recover information about the unknown true ancestral coalescent tree, population size, and the overall mutation rate from temporally spaced data, that is, from nucleotide sequences gathered at different times, from different individuals, in an evolving haploid population. We briefly discuss the methodological implications and show what can be inferred, in various practically relevant states of prior knowledge. We develop extensions for exponentially growing population size and joint estimation of substitution model parameters. We illustrate some of the important features of this approach on a genealogy of HIV-1 envelope (env) partial sequences. PMID:12136032

Estimating mutation parameters, population history and genealogy simultaneously from temporally spaced sequence data.

PubMed

Drummond, Alexei J; Nicholls, Geoff K; Rodrigo, Allen G; Solomon, Wiremu

2002-07-01

Molecular sequences obtained at different sampling times from populations of rapidly evolving pathogens and from ancient subfossil and fossil sources are increasingly available with modern sequencing technology. Here, we present a Bayesian statistical inference approach to the joint estimation of mutation rate and population size that incorporates the uncertainty in the genealogy of such temporally spaced sequences by using Markov chain Monte Carlo (MCMC) integration. The Kingman coalescent model is used to describe the time structure of the ancestral tree. We recover information about the unknown true ancestral coalescent tree, population size, and the overall mutation rate from temporally spaced data, that is, from nucleotide sequences gathered at different times, from different individuals, in an evolving haploid population. We briefly discuss the methodological implications and show what can be inferred, in various practically relevant states of prior knowledge. We develop extensions for exponentially growing population size and joint estimation of substitution model parameters. We illustrate some of the important features of this approach on a genealogy of HIV-1 envelope (env) partial sequences.

Model suggests potential for Porites coral population recovery after removal of anthropogenic disturbance (Luhuitou, Hainan, South China Sea).

PubMed

Zhao, Meixia; Riegl, Bernhard; Yu, Kefu; Shi, Qi; Zhang, Qiaomin; Liu, Guohui; Yang, Hongqiang; Yan, Hongqiang

2016-09-13

Population models are important for resource management and can inform about potential trajectories useful for planning purposes, even with incomplete monitoring data. From size frequency data on Luhuitou fringing reef, Hainan, South China Sea, a matrix population model of massive corals (Porites lutea) was developed and trajectories over 100 years under no disturbance and random disturbances were projected. The model reflects a largely open population of Porites lutea, with low local recruitment and preponderance of imported recruitment. Under no further disturbance, the population of Porites lutea will grow and its size structure will change from predominance of small size classes to large size classes. Therewith, total Porites cover will increase. Even under random disturbances every 10 to 20 years, the Porites population could remain viable, albeit at lower space cover. The models suggest recovery at Luhuitou following the removal of chronic anthropogenic disturbance. Extending the area of coral reef reserves to protect the open coral community and the path of connectivity is advisable and imperative for the conservation of Hainan's coral reefs.

Model suggests potential for Porites coral population recovery after removal of anthropogenic disturbance (Luhuitou, Hainan, South China Sea)

PubMed Central

Zhao, Meixia; Riegl, Bernhard; Yu, Kefu; Shi, Qi; Zhang, Qiaomin; Liu, Guohui; Yang, Hongqiang; Yan, Hongqiang

2016-01-01

Population models are important for resource management and can inform about potential trajectories useful for planning purposes, even with incomplete monitoring data. From size frequency data on Luhuitou fringing reef, Hainan, South China Sea, a matrix population model of massive corals (Porites lutea) was developed and trajectories over 100 years under no disturbance and random disturbances were projected. The model reflects a largely open population of Porites lutea, with low local recruitment and preponderance of imported recruitment. Under no further disturbance, the population of Porites lutea will grow and its size structure will change from predominance of small size classes to large size classes. Therewith, total Porites cover will increase. Even under random disturbances every 10 to 20 years, the Porites population could remain viable, albeit at lower space cover. The models suggest recovery at Luhuitou following the removal of chronic anthropogenic disturbance. Extending the area of coral reef reserves to protect the open coral community and the path of connectivity is advisable and imperative for the conservation of Hainan’s coral reefs. PMID:27622504

Theoretical and Experimental Study of Bacterial Colony Growth in 3D

NASA Astrophysics Data System (ADS)

Shao, Xinxian; Mugler, Andrew; Nemenman, Ilya

2014-03-01

Bacterial cells growing in liquid culture have been well studied and modeled. However, in nature, bacteria often grow as biofilms or colonies in physically structured habitats. A comprehensive model for population growth in such conditions has not yet been developed. Based on the well-established theory for bacterial growth in liquid culture, we develop a model for colony growth in 3D in which a homogeneous colony of cells locally consume a diffusing nutrient. We predict that colony growth is initially exponential, as in liquid culture, but quickly slows to sub-exponential after nutrient is locally depleted. This prediction is consistent with our experiments performed with E. coli in soft agar. Our model provides a baseline to which studies of complex growth process, such as such as spatially and phenotypically heterogeneous colonies, must be compared.

Latinos and public lands in California

Treesearch

Deborah J. Chavez

2005-01-01

Management of leisure resources in California would be incomplete with out consideration of the fastest growing ethnic group-Latinos. There are approximately 12 million Latinos in California (about one-third of California's population; Bear Facts, 2004), and this is expected to grow to 21 million Latinos by the year 2025 (about 40% of California's population...

LANDSCAPE CHANGE OF THE LAS VEGAS VALLEY, 1972 TO 1998

EPA Science Inventory

Las Vegas has become one of the fastest growing metropolitan areas in the United States. The cities population has doubled from 1980 to 1994 and in 1995 Las Vegas has surpassed the one million mark. The population of Las Vegas is currently growing at a rate of 7 percent annually....

Transplant experiments uncover Baltic Sea basin-specific responses in bacterioplankton community composition and metabolic activities.

PubMed

Lindh, Markus V; Figueroa, Daniela; Sjöstedt, Johanna; Baltar, Federico; Lundin, Daniel; Andersson, Agneta; Legrand, Catherine; Pinhassi, Jarone

2015-01-01

Anthropogenically induced changes in precipitation are projected to generate increased river runoff to semi-enclosed seas, increasing loads of terrestrial dissolved organic matter and decreasing salinity. To determine how bacterial community structure and functioning adjust to such changes, we designed microcosm transplant experiments with Baltic Proper (salinity 7.2) and Bothnian Sea (salinity 3.6) water. Baltic Proper bacteria generally reached higher abundances than Bothnian Sea bacteria in both Baltic Proper and Bothnian Sea water, indicating higher adaptability. Moreover, Baltic Proper bacteria growing in Bothnian Sea water consistently showed highest bacterial production and beta-glucosidase activity. These metabolic responses were accompanied by basin-specific changes in bacterial community structure. For example, Baltic Proper Pseudomonas and Limnobacter populations increased markedly in relative abundance in Bothnian Sea water, indicating a replacement effect. In contrast, Roseobacter and Rheinheimera populations were stable or increased in abundance when challenged by either of the waters, indicating an adjustment effect. Transplants to Bothnian Sea water triggered the initial emergence of particular Burkholderiaceae populations, and transplants to Baltic Proper water triggered Alteromonadaceae populations. Notably, in the subsequent re-transplant experiment, a priming effect resulted in further increases to dominance of these populations. Correlated changes in community composition and metabolic activity were observed only in the transplant experiment and only at relatively high phylogenetic resolution. This suggested an importance of successional progression for interpreting relationships between bacterial community composition and functioning. We infer that priming effects on bacterial community structure by natural episodic events or climate change induced forcing could translate into long-term changes in bacterial ecosystem process rates.

Transplant experiments uncover Baltic Sea basin-specific responses in bacterioplankton community composition and metabolic activities

PubMed Central

Lindh, Markus V.; Figueroa, Daniela; Sjöstedt, Johanna; Baltar, Federico; Lundin, Daniel; Andersson, Agneta; Legrand, Catherine; Pinhassi, Jarone

2015-01-01

Anthropogenically induced changes in precipitation are projected to generate increased river runoff to semi-enclosed seas, increasing loads of terrestrial dissolved organic matter and decreasing salinity. To determine how bacterial community structure and functioning adjust to such changes, we designed microcosm transplant experiments with Baltic Proper (salinity 7.2) and Bothnian Sea (salinity 3.6) water. Baltic Proper bacteria generally reached higher abundances than Bothnian Sea bacteria in both Baltic Proper and Bothnian Sea water, indicating higher adaptability. Moreover, Baltic Proper bacteria growing in Bothnian Sea water consistently showed highest bacterial production and beta-glucosidase activity. These metabolic responses were accompanied by basin-specific changes in bacterial community structure. For example, Baltic Proper Pseudomonas and Limnobacter populations increased markedly in relative abundance in Bothnian Sea water, indicating a replacement effect. In contrast, Roseobacter and Rheinheimera populations were stable or increased in abundance when challenged by either of the waters, indicating an adjustment effect. Transplants to Bothnian Sea water triggered the initial emergence of particular Burkholderiaceae populations, and transplants to Baltic Proper water triggered Alteromonadaceae populations. Notably, in the subsequent re-transplant experiment, a priming effect resulted in further increases to dominance of these populations. Correlated changes in community composition and metabolic activity were observed only in the transplant experiment and only at relatively high phylogenetic resolution. This suggested an importance of successional progression for interpreting relationships between bacterial community composition and functioning. We infer that priming effects on bacterial community structure by natural episodic events or climate change induced forcing could translate into long-term changes in bacterial ecosystem process rates. PMID:25883589

Population variables and life-history characteristics of the alligator pipefish Syngnathoides biaculeatus, in Papua New Guinea.

PubMed

Barrows, A P W; Martin-Smith, K M; Baine, M S P

2009-03-01

Population structure and life-history variables of the widely distributed alligator pipefish Syngnathoides biaculeatus were characterized in Bootless Bay, Papua New Guinea over the course of 11 months. There was little evidence of seasonality with four focal populations showing no significant change in abundance. Similarly, the sex ratio remained 1:1 for all but 1 month. Reproductive males carrying eggs (148-278 mm in total length, L(T)) were found in all months. Brood size was significantly, positively related to male L(T) for newly laid broods only. Maximum observed brood size was 351 and mean +/-s.d. brood size was 238 +/- 57 for newly laid broods. Juveniles and males showed no change in mean L(T) over the year while slightly smaller females were captured in November 2006 and September 2007. Males were significantly longer than females so von Bertalanffy growth coefficients were estimated separately for each sex: males L(infinity)= 285 mm, K = 0.82 year(-1) and females L(infinity)= 261 mm, K = 1.10 year(-1). These estimates suggest that this species grows rapidly and has a short-life span. In the context of growing concern about overexploitation of syngnathids, a rapid growth rate combined with year round reproductive activity suggests that the tropical S. biaculeatus may be relatively resilient with regard to fishing pressure.

[Biological evolution and ancient DNA].

PubMed

Debruyne, Régis; Barriel, Véronique

2006-05-01

Twenty years after the advent of ancient DNA studies, this discipline seems to have reached the maturity formerly lacking to the fulfilment of its objectives. In its early development paleogenetics, as it is now acknowledged, had to cope with very limited data due to the technical limitations of molecular biology. It led to phylogenetic assumptions often limited in their scope and sometimes non-focused or even spurious results that cast the reluctance of the scientific community. This time seems now over and huge amounts of sequences have become available which overcome the former limitations and bridge the gap between paleogenetics, genomics and population biology. The recent studies over the charismatic woolly mammoth (independent sequencing of the whole mitochondrial genome and of millions of base pairs of the nuclear genome) exemplify the growing accuracy of ancient DNA studies thanks to new molecular approaches. From the earliest publications up to now, the number of mammoth nucleotides was multiplied by 100,000. Likewise, populational approaches of ice-age taxa provide new historical scenarios about the diversification and extinction of the Pleistocene megafauna on the one hand, and about the processes of domestication of animal and vegetal species by Man on the other. They also shed light on the differential structure of molecular diversity between short-term populational research (below 2 My) and long-term (over 2 My) phylogenetic approaches. All those results confirm the growing importance of paleogenetics among the evolutionary biology disciplines.

Chemical defense and chemical variation in some tropical Pacific species of Halimeda (Halimedaceae; Chlorophyta)

NASA Astrophysics Data System (ADS)

Paul, Valerie J.; van Alstyne, Kathryn L.

1988-03-01

Over a dozen species of the genus Halimeda have been chemically investigated and found to produce the diterpenoid metabolites halimedatrial (1) and halimedatetraacetate (2) in varying concentrations. These meabolites have been proposed to play a role in chemical defense against herbivores based on their chemical structures and their demonstrated biological activities in laboratory and aquarium assays. We examined and compared the feeding deterrent effects of these two compounds tovard herbivorous fishes in field experiments on Guam reefs. Halimedatrial is a more effective feeding deterrent than halimedatetraacetate. It is the major secondary metabolite in young Halimeda macroloba and in the newly produced segments of growing plants. The organic extracts from young plants and new segments were significantly more deterrent than extracts from mature plant tissue. Some populations of Halimeda growing in reef-slope habitats, where herbivory is intense, also have high concentrations of halimedatrial. We compared extracts between reef slope and reef flat collections of Halimeda opuntia on Guam and Pohnpei (= Ponape), and H. discoidea and H. macroloba on Guam. We found that halimedtrial was the major metabolite in reef-slope collections of H. opuntia from Pohnpei and Pago Bay, Guam, and that halimedatetraacetate was the major metabolite a non-reef slope populations. In the cases examined, chemical defenses were greatest in (1) plant parts and (2) populations that were at greatest risk to herbivores.

Cell lineage patterns in the shoot meristem of the sunflower embryo in the dry seed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jegla, D.E.; Sussex, I.M.

1989-01-01

We mapped the fate of cells in the shoot meristem of the dry-seed embryo of sunflower, Helianthus annuus L. cv. Peredovic, using irradiation-induced somatic sectors. We analyzed 249 chlorophyll-deficient or glabrous (hairless) sectors generated in 236 plants. Most sectors observed in the inflorescence extended into vegetative nodes. Thus cell lineages that ultimately gave rise to reproductive structures also contributed to vegetative structures. No single sector extended the entire length of the shoot. Thus the shoot is not derived from one or a few apical initials. Rather, the position, vertical extent, and width of the sectors at different levels of themore » shoot suggest that the shoot is derived from three to four circumferential populations of cells in each of three cell layers of the embryo meristem. Sectors had no common boundaries even in plants with two or three independent sectors, but varied in extent and overlapped along the length of the shoot. Thus individual cells in a single circumferential population behaved independently to contribute lineages of different vertical extents to the growing shoot. The predicted number of circumferential populations of cells as well as the apparent cell number in each population was consistent with the actual number of cells in the embryo meristem observed in histological sections.« less

Simulated rRNA/DNA Ratios Show Potential To Misclassify Active Populations as Dormant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steven, Blaire; Hesse, Cedar; Soghigian, John

The use of rRNA/DNA ratios derived from surveys of rRNA sequences in RNA and DNA extracts is an appealing but poorly validated approach to infer the activity status of environmental microbes. To improve the interpretation of rRNA/DNA ratios, we performed simulations to investigate the effects of community structure, rRNA amplification, and sampling depth on the accuracy of rRNA/DNA ratios in classifying bacterial populations as “active” or “dormant.” Community structure was an insignificant factor. In contrast, the extent of rRNA amplification that occurs as cells transition from dormant to growing had a significant effect (P < 0.0001) on classification accuracy, withmore » misclassification errors ranging from 16 to 28%, depending on the rRNA amplification model. The error rate increased to 47% when communities included a mixture of rRNA amplification models, but most of the inflated error was false negatives (i.e., active populations misclassified as dormant). Sampling depth also affected error rates (P < 0.001). Inadequate sampling depth produced various artifacts that are characteristic of rRNA/DNA ratios generated from real communities. These data show important constraints on the use of rRNA/DNA ratios to infer activity status. Whereas classification of populations as active based on rRNA/DNA ratios appears generally valid, classification of populations as dormant is potentially far less accurate.« less

Linking macroscopic with microscopic neuroanatomy using synthetic neuronal populations.

PubMed

Schneider, Calvin J; Cuntz, Hermann; Soltesz, Ivan

2014-10-01

Dendritic morphology has been shown to have a dramatic impact on neuronal function. However, population features such as the inherent variability in dendritic morphology between cells belonging to the same neuronal type are often overlooked when studying computation in neural networks. While detailed models for morphology and electrophysiology exist for many types of single neurons, the role of detailed single cell morphology in the population has not been studied quantitatively or computationally. Here we use the structural context of the neural tissue in which dendritic trees exist to drive their generation in silico. We synthesize the entire population of dentate gyrus granule cells, the most numerous cell type in the hippocampus, by growing their dendritic trees within their characteristic dendritic fields bounded by the realistic structural context of (1) the granule cell layer that contains all somata and (2) the molecular layer that contains the dendritic forest. This process enables branching statistics to be linked to larger scale neuroanatomical features. We find large differences in dendritic total length and individual path length measures as a function of location in the dentate gyrus and of somatic depth in the granule cell layer. We also predict the number of unique granule cell dendrites invading a given volume in the molecular layer. This work enables the complete population-level study of morphological properties and provides a framework to develop complex and realistic neural network models.

Linking Macroscopic with Microscopic Neuroanatomy Using Synthetic Neuronal Populations

PubMed Central

Schneider, Calvin J.; Cuntz, Hermann; Soltesz, Ivan

2014-01-01

Dendritic morphology has been shown to have a dramatic impact on neuronal function. However, population features such as the inherent variability in dendritic morphology between cells belonging to the same neuronal type are often overlooked when studying computation in neural networks. While detailed models for morphology and electrophysiology exist for many types of single neurons, the role of detailed single cell morphology in the population has not been studied quantitatively or computationally. Here we use the structural context of the neural tissue in which dendritic trees exist to drive their generation in silico. We synthesize the entire population of dentate gyrus granule cells, the most numerous cell type in the hippocampus, by growing their dendritic trees within their characteristic dendritic fields bounded by the realistic structural context of (1) the granule cell layer that contains all somata and (2) the molecular layer that contains the dendritic forest. This process enables branching statistics to be linked to larger scale neuroanatomical features. We find large differences in dendritic total length and individual path length measures as a function of location in the dentate gyrus and of somatic depth in the granule cell layer. We also predict the number of unique granule cell dendrites invading a given volume in the molecular layer. This work enables the complete population-level study of morphological properties and provides a framework to develop complex and realistic neural network models. PMID:25340814

Genetic and metabolite diversity of Sardinian populations of Helichrysum italicum.

PubMed

Melito, Sara; Sias, Angela; Petretto, Giacomo L; Chessa, Mario; Pintore, Giorgio; Porceddu, Andrea

2013-01-01

Helichrysum italicum (Asteraceae) is a small shrub endemic to the Mediterranean Basin, growing in fragmented and diverse habitats. The species has attracted attention due to its secondary metabolite content, but little effort has as yet been dedicated to assessing the genetic and metabolite diversity present in these populations. Here, we describe the diversity of 50 H. italicum populations collected from a range of habitats in Sardinia. H. italicum plants were AFLP fingerprinted and the composition of their leaf essential oil characterized by GC-MS. The relationships between the genetic structure of the populations, soil, habitat and climatic variables and the essential oil chemotypes present were evaluated using Bayesian clustering, contingency analyses and AMOVA. The Sardinian germplasm could be partitioned into two AFLP-based clades. Populations collected from the southwestern region constituted a homogeneous group which remained virtually intact even at high levels of K. The second, much larger clade was more diverse. A positive correlation between genetic diversity and elevation suggested the action of natural purifying selection. Four main classes of compounds were identified among the essential oils, namely monoterpenes, oxygenated monoterpenes, sesquiterpenes and oxygenated sesquiterpenes. Oxygenated monoterpene levels were significantly correlated with the AFLP-based clade structure, suggesting a correspondence between gene pool and chemical diversity. The results suggest an association between chemotype, genetic diversity and collection location which is relevant for the planning of future collections aimed at identifying valuable sources of essential oil.

Simulated rRNA/DNA Ratios Show Potential To Misclassify Active Populations as Dormant

DOE PAGES

Steven, Blaire; Hesse, Cedar; Soghigian, John; ...

2017-03-31

The use of rRNA/DNA ratios derived from surveys of rRNA sequences in RNA and DNA extracts is an appealing but poorly validated approach to infer the activity status of environmental microbes. To improve the interpretation of rRNA/DNA ratios, we performed simulations to investigate the effects of community structure, rRNA amplification, and sampling depth on the accuracy of rRNA/DNA ratios in classifying bacterial populations as “active” or “dormant.” Community structure was an insignificant factor. In contrast, the extent of rRNA amplification that occurs as cells transition from dormant to growing had a significant effect (P < 0.0001) on classification accuracy, withmore » misclassification errors ranging from 16 to 28%, depending on the rRNA amplification model. The error rate increased to 47% when communities included a mixture of rRNA amplification models, but most of the inflated error was false negatives (i.e., active populations misclassified as dormant). Sampling depth also affected error rates (P < 0.001). Inadequate sampling depth produced various artifacts that are characteristic of rRNA/DNA ratios generated from real communities. These data show important constraints on the use of rRNA/DNA ratios to infer activity status. Whereas classification of populations as active based on rRNA/DNA ratios appears generally valid, classification of populations as dormant is potentially far less accurate.« less

Cancer in light of experimental evolution.

PubMed

Sprouffske, Kathleen; Merlo, Lauren M F; Gerrish, Philip J; Maley, Carlo C; Sniegowski, Paul D

2012-09-11

Cancer initiation, progression, and the emergence of therapeutic resistance are evolutionary phenomena of clonal somatic cell populations. Studies in microbial experimental evolution and the theoretical work inspired by such studies are yielding deep insights into the evolutionary dynamics of clonal populations, yet there has been little explicit consideration of the relevance of this rapidly growing field to cancer biology. Here, we examine how the understanding of mutation, selection, and spatial structure in clonal populations that is emerging from experimental evolution may be applicable to cancer. Along the way, we discuss some significant ways in which cancer differs from the model systems used in experimental evolution. Despite these differences, we argue that enhanced prediction and control of cancer may be possible using ideas developed in the context of experimental evolution, and we point out some prospects for future research at the interface between these traditionally separate areas. Copyright © 2012 Elsevier Ltd. All rights reserved.

Is Low Fertility Really a Problem? Population Aging, Dependency, and Consumption*

PubMed Central

2015-01-01

Longer lives and fertility far below the replacement level of 2.1 births per woman are leading to rapid population aging in many countries. Many observers are concerned that aging will adversely affect public finances and standards of living. Analysis of newly available National Transfer Accounts data for 40 countries shows that fertility well above replacement would typically be most beneficial for government budgets. However, fertility near replacement would be most beneficial for standards of living when the analysis includes the effects of age structure on families as well as governments. And fertility below replacement would maximize per capita consumption when the cost of providing capital for a growing labor force is taken into account. While low fertility will indeed challenge government programs and very low fertility undermines living standards, we find that moderately low fertility and population decline favor the broader material standard of living PMID:25301626

Cancer in Light of Experimental Evolution

PubMed Central

Sprouffske, Kathleen; Merlo, Lauren M.F.; Gerrish, Philip J.; Maley, Carlo C.; Sniegowski, Paul D.

2012-01-01

Cancer initiation, progression, and the emergence of therapeutic resistance are evolutionary phenomena of clonal somatic cell populations. Studies in microbial experimental evolution and the theoretical work inspired by such studies are yielding deep insights into the evolutionary dynamics of clonal populations, yet there has been little explicit consideration of the relevance of this rapidly growing field to cancer biology. Here, we examine how the understanding of mutation, selection, and spatial structure in clonal populations that is emerging from experimental evolution may be applicable to cancer. Along the way, we discuss some significant ways in which cancer differs from the model systems used in experimental evolution. Despite these differences, we argue that enhanced prediction and control of cancer may be possible using ideas developed in the context of experimental evolution, and we point out some prospects for future research at the interface between these traditionally separate areas. PMID:22975007

Evolutionary Game Theory in Growing Populations

NASA Astrophysics Data System (ADS)

Melbinger, Anna; Cremer, Jonas; Frey, Erwin

2010-10-01

Existing theoretical models of evolution focus on the relative fitness advantages of different mutants in a population while the dynamic behavior of the population size is mostly left unconsidered. We present here a generic stochastic model which combines the growth dynamics of the population and its internal evolution. Our model thereby accounts for the fact that both evolutionary and growth dynamics are based on individual reproduction events and hence are highly coupled and stochastic in nature. We exemplify our approach by studying the dilemma of cooperation in growing populations and show that genuinely stochastic events can ease the dilemma by leading to a transient but robust increase in cooperation.

Phenotypically heterogeneous populations in spatially heterogeneous environments

NASA Astrophysics Data System (ADS)

Patra, Pintu; Klumpp, Stefan

2014-03-01

The spatial expansion of a population in a nonuniform environment may benefit from phenotypic heterogeneity with interconverting subpopulations using different survival strategies. We analyze the crossing of an antibiotic-containing environment by a bacterial population consisting of rapidly growing normal cells and slow-growing, but antibiotic-tolerant persister cells. The dynamics of crossing is characterized by mean first arrival times and is found to be surprisingly complex. It displays three distinct regimes with different scaling behavior that can be understood based on an analytical approximation. Our results suggest that a phenotypically heterogeneous population has a fitness advantage in nonuniform environments and can spread more rapidly than a homogeneous population.

Barriers and facilitators affecting African Americans continuation into graduate programs in nursing.

PubMed

Mingo, Aunderia Doreen

2008-01-01

The population in the United States (US) is becoming more and more diverse. With each year the minority population in the US continues to grow. In the year 2000 there were over 281 million Americans with approximately 23% of them being minorities (US Census, 2000). African-Americans accounted for 34.6 million of the population or 12.3% in the 2000 census. Yet despite their growing numbers in the general population African-American Registered Nurses (RNs) only accounted for 4.9% of the total nurse population in the 2002 National Sample Survey of RN's (Health Resources Services Administration [HRSA], 2002).

Aging in Poland.

PubMed

Leszko, Magdalena; Zając-Lamparska, Ludmila; Trempala, Janusz

2015-10-01

With 38 million residents, Poland has the eighth-largest population in Europe. A successful transition from communism to democracy, which began in 1989, has brought several significant changes to the country's economic development, demographic structure, quality of life, and public policies. As in the other European countries, Poland has been facing a rapid increase in the number of older adults. Currently, the population 65 and above is growing more rapidly than the total population and this discrepancy will have important consequences for the country's economy. As the population ages, there will be increased demands to improve Poland's health care and retirement systems. This article aims to provide a brief overview of the demographic trends in Poland as well a look at the country's major institutions of gerontology research. The article also describes key public policies concerning aging and how these may affect the well-being of Poland's older adults. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

New light on old problem: population.

PubMed

Padilla, T

1982-01-01

A central issue of the Third Asian and Pacific Population Conference, to be held in Sri Lanka in September 1982, is the need for full recognition on the part of developing countries that an integrated approach to population and development is essential. Such an approach requires the following: management of internal migration and urbanization; women's participation in development; and increased involvement in promoting family planning, family welfare, and family health programs. Of much concern is the fact that the ESCAP region's urban population is projected to grow from 660 million in 1980 to 1347 million by the year 2000. Much of this increase will occur in the largest cities. Unplanned urbanization and a growing population reservoir in rural areas will continue to spur movements to the cities, aggravating the urban malaise, yet migration is young people's only option if rural populations are to survive. These problems plague most governments. A recent conference held in Rome urged governments to formulate comprehensive population policies and programs, to specify goals on the rate of population growth and on the distribution of population between urban and rural areas, and to plan for the redistribution of population. The conference also recommended that cities pay attention to problems of the shantytown and slum dwellers who are principally rural migrants and the urban poor. In addition the region's corps of development planners and experts worry about the staggering increase in migration by 3rd world guest workers to the high income OPEC members in the Middle East and the industrialized market economy nations. The proper management of international migration should increase the reabsorptive capacity of sending countries to ensure the reintegration of returning off-loaded guest workers and should try to prevent the rural stagnation due to large scale migration by the young and the better educated from the countryside. Internal and international migration give women an opportunity to discover their great development potential. Yet, more generally, women breaking out of social structures that foster dependency and exploitation are in need of more than simple, single factor solutions. Emerging relationships between declining mortality levels and women's participation in development and economic activities will be explored at the Third Asian and Pacific Population Conference.

Ecosystem Structure Changes in the Turkish Seas as a Response to Overfishing

NASA Astrophysics Data System (ADS)

Gazihan Akoglu, Ayse; Salihoglu, Baris; Akoglu, Ekin; Kideys, Ahmet E.

2013-04-01

Human population in Turkey has grown more than five-fold since its establishment in 1923 and more than 73 million people are currently living in the country. Turkey is surrounded by partially connected seas (the Black Sea, the Sea of Marmara, the Aegean Sea and the Mediterranean Sea) each of which has significantly different productivity levels and ecosystem characteristics. Increasing human population with its growing socio-economic needs has generated an intensive fishing pressure on the fish stocks in its exclusive economic zone. Fishing grounds in the surrounding seas were exploited with different fishing intensities depending upon their productivity level and catch rates. Hence, the responses of these different ecosystems to overfishing have been realized differently. In this study, changes of the ecosystem structures in the Turkish Seas were comparatively investigated by ecosystem indices such as Marine Trophic Index (MTI), Fishing in Balance (FiB) and Primary Production Required (PPR) to assess the degree of sustainability of the fish stocks for future generations.

Population structure and linkage disequilibrium in Lupinus albus L. germplasm and its implication for association mapping.

PubMed

Iqbal, Muhammad Javed; Mamidi, Sujan; Ahsan, Rubina; Kianian, Shahryar F; Coyne, Clarice J; Hamama, Anwar A; Narina, Satya S; Bhardwaj, Harbans L

2012-08-01

White lupin (Lupinus albus L.) has been around since 300 B.C. and is recognized for its ability to grow on poor soils and application as green manure in addition to seed harvest. The seed has very high levels of protein (33-47 %) and oil (6-13 %). It also has many secondary metabolites that are potentially of nutraceutical value to animals and humans. Despite such a great potential, lupins role in modern agriculture began only in the twentieth century. Although a large collection of Lupinus germplasm accessions is available worldwide, rarely have they been genetically characterized. Additionally, scarce genomic resources in terms of recombinant populations and genome information have been generated for L. albus. With the advancement in association mapping methods, the natural populations have the potential to replace the recombinant populations in gene mapping and marker-trait associations. Therefore, we studied the genetic similarity, population structure and marker-trait association in a USDA germplasm collection for their current and future application in this crop improvement. A total of 122 PI (Plant Inventory) lines were screened with 18 AFLP primer pairs that generated 2,277 fragments. A subset of 892 polymorphic markers with MAF >0.05 (minor allele frequency) were used for association mapping. The cluster analysis failed to group accessions on the basis of their passport information, and a weak structure and low linkage disequilibrium (LD) were observed indicating the usefulness of the collection for association mapping. Moreover, we were also able to identify two markers (a p value of 1.53 × 10(-4) and 2.3 × 10(-4)) that explained 22.69 and 20.5 % of seed weight variation determined using R (LR) (2) . The implications of lack of geographic clustering, population structure, low LD and the ability of AFLP to map seed weight trait using association mapping and the usefulness of the PI collections in breeding programs are discussed.

The Changing Urban Landscape: Interconnections Between Racial/Ethnic Segregation and Exposure in the Study of Race-Specific Violence Over Time

PubMed Central

Stansfield, Richard

2015-01-01

Objectives. We investigated how racial/ethnic shifts in the urban landscape influence race-specific violence by considering changes in the size of the Hispanic population, racial/ethnic contact, and racial segregation patterns. Methods. We used a time-series approach incorporating 4 decennial periods (1980, 1990, 2000, and 2010) to determine whether racial/ethnic demographic changes in 144 US cities influenced White and Black homicide rates. Sources included census and Uniform Crime Reports Supplemental Homicide Report data. Results. The growing diversity in the residential population of US cities contributed to the dramatic decline in homicide rates over time, but the effects differed by racial group. Exposure between Hispanics and Blacks and the growing presence of Hispanics led to a reduced Black homicide trend but had no impact on Whites, after adjustment for economic shifts and other important structural features in US cities. Conclusions. Our research highlights the importance of paying closer attention to exposure and integration between immigrants and existing racial groups. Failure to consider racial/ethnic contact and the racial nature of urban violence may produce misleading results in studies of associations between Hispanic immigration and crime. PMID:26180967

The Changing Urban Landscape: Interconnections Between Racial/Ethnic Segregation and Exposure in the Study of Race-Specific Violence Over Time.

PubMed

Parker, Karen F; Stansfield, Richard

2015-09-01

We investigated how racial/ethnic shifts in the urban landscape influence race-specific violence by considering changes in the size of the Hispanic population, racial/ethnic contact, and racial segregation patterns. We used a time-series approach incorporating 4 decennial periods (1980, 1990, 2000, and 2010) to determine whether racial/ethnic demographic changes in 144 US cities influenced White and Black homicide rates. Sources included census and Uniform Crime Reports Supplemental Homicide Report data. The growing diversity in the residential population of US cities contributed to the dramatic decline in homicide rates over time, but the effects differed by racial group. Exposure between Hispanics and Blacks and the growing presence of Hispanics led to a reduced Black homicide trend but had no impact on Whites, after adjustment for economic shifts and other important structural features in US cities. Our research highlights the importance of paying closer attention to exposure and integration between immigrants and existing racial groups. Failure to consider racial/ethnic contact and the racial nature of urban violence may produce misleading results in studies of associations between Hispanic immigration and crime.

Older Adults with Intellectual Disabilities: Targets for Increasing Victimization, a Call for a Preemptive Screening Policy

ERIC Educational Resources Information Center

Strasser, Sheryl; O'Quin, Karen; Price, Thomas; Leyda, Elizabeth

2012-01-01

The aging population is a rapidly growing demographic in the United States. Isolation, limited autonomy, and declining physical and mental health render many older adults vulnerable to abuse, neglect, and exploitation. As the population grows, so does the need for Adult Protective Services (APS). This article highlights an ultrasensitive subgroup…

Lone atrial fibrillation: where are we now?

PubMed

Potpara, Tatjana S; Lip, Gregory Y

2011-10-01

There is a growing pandemic of atrial fibrillation (AF), affecting nearly 2% of the general adult population. Atrial fibrillation is commonly associated with structural heart disease, and AF itself causes a sequence of complex processes of electrical, contractile, and structural remodeling of the atrial myocardium, which facilitate further AF progression. Nonetheless, AF may also affect individuals aged ≤ 65 years who have no evidence of associated cardiopulmonary or other disease, including hypertension; this is otherwise referred to as "lone" AF and is considered to have a generally favorable prognosis. The true prevalence of lone AF is unknown. Growing insights into the diversity of numerous mechanisms involved in the pathogenesis of AF, including acute atrial stretch, structural and electrophysiological alterations, systemic inflammation, oxidative stress, autonomic imbalance, genetic predisposition, and many others, and increasing recognition of novel risk factors for AF, including obesity, metabolic syndrome, subclinical atherosclerosis, sleep apnea, alcohol consumption, and endurance sports, suggest that apparently lone AF might not be so "lone" in many patients, which could have important prognostic and therapeutic implications. In this article, we summarize the current knowledge of epidemiology, etiopathogenesis, and pathophysiology of so-called lone AF and discuss the issues of long-term prognosis and management of patients who have an apparently lone AF.

Influence of Nutrient Availability and Quorum Sensing on the Formation of Metabolically Inactive Microcolonies Within Structurally Heterogeneous Bacterial Biofilms: An Individual-Based 3D Cellular Automata Model.

PubMed

Machineni, Lakshmi; Rajapantul, Anil; Nandamuri, Vandana; Pawar, Parag D

2017-03-01

The resistance of bacterial biofilms to antibiotic treatment has been attributed to the emergence of structurally heterogeneous microenvironments containing metabolically inactive cell populations. In this study, we use a three-dimensional individual-based cellular automata model to investigate the influence of nutrient availability and quorum sensing on microbial heterogeneity in growing biofilms. Mature biofilms exhibited at least three structurally distinct strata: a high-volume, homogeneous region sandwiched between two compact sections of high heterogeneity. Cell death occurred preferentially in layers in close proximity to the substratum, resulting in increased heterogeneity in this section of the biofilm; the thickness and heterogeneity of this lowermost layer increased with time, ultimately leading to sloughing. The model predicted the formation of metabolically dormant cellular microniches embedded within faster-growing cell clusters. Biofilms utilizing quorum sensing were more heterogeneous compared to their non-quorum sensing counterparts, and resisted sloughing, featuring a cell-devoid layer of EPS atop the substratum upon which the remainder of the biofilm developed. Overall, our study provides a computational framework to analyze metabolic diversity and heterogeneity of biofilm-associated microorganisms and may pave the way toward gaining further insights into the biophysical mechanisms of antibiotic resistance.

Modelling the balance between quiescence and cell death in normal and tumour cell populations.

PubMed

Spinelli, Lorenzo; Torricelli, Alessandro; Ubezio, Paolo; Basse, Britta

2006-08-01

When considering either human adult tissues (in vivo) or cell cultures (in vitro), cell number is regulated by the relationship between quiescent cells, proliferating cells, cell death and other controls of cell cycle duration. By formulating a mathematical description we see that even small alterations of this relationship may cause a non-growing population to start growing with doubling times characteristic of human tumours. Our model consists of two age structured partial differential equations for the proliferating and quiescent cell compartments. Model parameters are death rates from and transition rates between these compartments. The partial differential equations can be solved for the steady-age distributions, giving the distribution of the cells through the cell cycle, dependent on specific model parameter values. Appropriate formulas can then be derived for various population characteristic quantities such as labelling index, proliferation fraction, doubling time and potential doubling time of the cell population. Such characteristic quantities can be estimated experimentally, although with decreasing precision from in vitro, to in vivo experimental systems and to the clinic. The model can be used to investigate the effects of a single alteration of either quiescence or cell death control on the growth of the whole population and the non-trivial dependence of the doubling time and other observable quantities on particular underlying cell cycle scenarios of death and quiescence. The model indicates that tumour evolution in vivo is a sequence of steady-states, each characterised by particular death and quiescence rate functions. We suggest that a key passage of carcinogenesis is a loss of the communication between quiescence, death and cell cycle machineries, causing a defect in their precise, cell cycle dependent relationship.

Population ageing in Lebanon: current status, future prospects and implications for policy.

PubMed Central

Sibai, Abla Mehio; Sen, Kasturi; Baydoun, May; Saxena, Prem

2004-01-01

During the past three decades, fast declines in fertility and mortality in Lebanon have created a compressed demographic transition, a growing trend towards survival into later life, and a larger proportion of elderly people in the population. Projections show that people aged 65 years and over are expected to constitute 10.2% of the population by 2025. Nevertheless, changes to the structure and composition of the population remain unmatched by any corresponding increase in support measures either through formal channels such as pension plans or through health or socioeconomic security measures such as the provision of subsidies for health care, home help or any form of nursing care. This means that an older person is forced to be dependent upon family support if it exists. We examine demographic trends of population ageing in Lebanon between 1970 and 1995 and provide projections until 2025. Variations in population ageing within the country are also considered. We also assess health care and social policy implications of demographic changes in the context of health and economic sector reforms initiated recently by the state, and explore their impact upon the expanding population of elderly people. PMID:15112011

Toward the 21st Century. A Continent in Crisis: Building a Future for Africa in the 21st Century. A Special Report by the Population Institute to the 101st Congress.

ERIC Educational Resources Information Center

Burdett, Hal; And Others

Africa's population is now 630 million, and it is growing faster than any other region in the world. But while Africa's population grows by 3.1 percent annually, the continent's food supply increases by only 1.1 percent per year. Throughout the 1980s more and more African governments have agreed that lasting development is possible only if…

Structure coefficients and strategy selection in multiplayer games.

PubMed

McAvoy, Alex; Hauert, Christoph

2016-01-01

Evolutionary processes based on two-player games such as the Prisoner's Dilemma or Snowdrift Game are abundant in evolutionary game theory. These processes, including those based on games with more than two strategies, have been studied extensively under the assumption that selection is weak. However, games involving more than two players have not received the same level of attention. To address this issue, and to relate two-player games to multiplayer games, we introduce a notion of reducibility for multiplayer games that captures what it means to break down a multiplayer game into a sequence of interactions with fewer players. We discuss the role of reducibility in structured populations, and we give examples of games that are irreducible in any population structure. Since the known conditions for strategy selection, otherwise known as [Formula: see text]-rules, have been established only for two-player games with multiple strategies and for multiplayer games with two strategies, we extend these rules to multiplayer games with many strategies to account for irreducible games that cannot be reduced to those simpler types of games. In particular, we show that the number of structure coefficients required for a symmetric game with [Formula: see text]-player interactions and [Formula: see text] strategies grows in [Formula: see text] like [Formula: see text]. Our results also cover a type of ecologically asymmetric game based on payoff values that are derived not only from the strategies of the players, but also from their spatial positions within the population.

A global fingerprint of macro-scale changes in urban structure from 1999 to 2009

NASA Astrophysics Data System (ADS)

Frolking, Steve; Milliman, Tom; Seto, Karen C.; Friedl, Mark A.

2013-06-01

Urban population now exceeds rural population globally, and 60-80% of global energy consumption by households, businesses, transportation, and industry occurs in urban areas. There is growing evidence that built-up infrastructure contributes to carbon emissions inertia, and that investments in infrastructure today have delayed climate cost in the future. Although the United Nations statistics include data on urban population by country and select urban agglomerations, there are no empirical data on built-up infrastructure for a large sample of cities. Here we present the first study to examine changes in the structure of the world’s largest cities from 1999 to 2009. Combining data from two space-borne sensors—backscatter power (PR) from NASA’s SeaWinds microwave scatterometer, and nighttime lights (NL) from NOAA’s defense meteorological satellite program/operational linescan system (DMSP/OLS)—we report large increases in built-up infrastructure stock worldwide and show that cities are expanding both outward and upward. Our results reveal previously undocumented recent and rapid changes in urban areas worldwide that reflect pronounced shifts in the form and structure of cities. Increases in built-up infrastructure are highest in East Asian cities, with Chinese cities rapidly expanding their material infrastructure stock in both height and extent. In contrast, Indian cities are primarily building out and not increasing in verticality. This new dataset will help characterize the structure and form of cities, and ultimately improve our understanding of how cities affect regional-to-global energy use and greenhouse gas emissions.

Whole-Genome Analysis Illustrates Global Clonal Population Structure of the Ubiquitous Dermatophyte Pathogen Trichophyton rubrum

PubMed Central

Persinoti, Gabriela F.; Martinez, Diego A.; Li, Wenjun; Döğen, Aylin; Billmyre, R. Blake; Averette, Anna; Goldberg, Jonathan M.; Shea, Terrance; Young, Sarah; Zeng, Qiandong; Oliver, Brian G.; Barton, Richard; Metin, Banu; Hilmioğlu-Polat, Süleyha; Ilkit, Macit; Gräser, Yvonne; Martinez-Rossi, Nilce M.; White, Theodore C.; Heitman, Joseph; Cuomo, Christina A.

2018-01-01

Dermatophytes include fungal species that infect humans, as well as those that also infect other animals or only grow in the environment. The dermatophyte species Trichophyton rubrum is a frequent cause of skin infection in immunocompetent individuals. While members of the T. rubrum species complex have been further categorized based on various morphologies, their population structure and ability to undergo sexual reproduction are not well understood. In this study, we analyze a large set of T. rubrum and T. interdigitale isolates to examine mating types, evidence of mating, and genetic variation. We find that nearly all isolates of T. rubrum are of a single mating type, and that incubation with T. rubrum “morphotype” megninii isolates of the other mating type failed to induce sexual development. While the region around the mating type locus is characterized by a higher frequency of SNPs compared to other genomic regions, we find that the population is remarkably clonal, with highly conserved gene content, low levels of variation, and little evidence of recombination. These results support a model of recent transition to asexual growth when this species specialized to growth on human hosts. PMID:29467168

Health policies and intervention strategies: a description of current issues and approaches to care of the public health and health care system in the United Arab emirates.

PubMed

Mosaad, Aliye T; Younis, Mustafa Z

2014-01-01

The demographic factors of the United Arab Emirates (UAE) have changed drastically within one generation. This is evident in how quickly it has moved from a developing nation, where fishing was once the main source of income, to a country that is quite developed, competing on a global level. From one perspective, socio-economic progress has brought many benefits to the population. These include improved education, better access to health care, and safe drinking water. However, on the other hand, economic development has been the cause for changes in lifestyles, eating habits, and traditional societal and family structures. Over time, these changes have added up, creating an unprecedented impact on the population's health. This impact has crept up onto the society until suddenly a notable epidemic has become recognized in the country. According to the UAE Ministry of Health, 19.5 percent of the UAE population has diabetes, making it the second highest rate in the world. The structure and responsibilities of the current UAE health care systems along with other cultural factors were investigated in order to determine their impact on the growing epidemic.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarath, Gautam

This grant funded work was undertaken to develop fundamental biological knowledge of the factors affecting the complex plant trait “fitness” in switchgrass (Panicum virgatum L.), a plant being developed as a biomass crop. Using a diverse range of latitudinally-adapted switchgrass plants, genomic, molecular and physiological studies were performed to track a number of different aspects of plant genetics and physiology over the course of the growing season. Work was performed on both genetically unrelated and genetically related plants. Plants were established in the field from seedlings raised in a greenhouse, or from clones present in other field nurseries. Field grownmore » plants were used as the source of all tissues. The three objectives of this proposal were:(1) Transcript Profiling, Metabolomics, and C and N Partitioning and Recycling in Crowns and Rhizomes of Switchgrass over two growing seasons; (2) Gene Profiling During Regreening and Dormancy of Bulked Segregants; (3) Extent of Linkage Disequilibrium in Populations for Adaptation and Fitness Traits Being Developed for Central and Northern USA, that Show Significant Heterosis. Objective 1 results: Plants were labeled using 13CO2 (a stable isotope) using an acrylic chamber constructed specifically for this purpose. Plants became labeled with 13C and label decayed in aerial tissues over the course of the growing season. Varying amounts of 13C were recovered in the rhizomes. These data are being analyzed. Plants were also labeled with 15N-urea. Plants absorbed significant amounts of label that was remobilized to the growing shoots. N-dynamics would suggest that a portion of the 15N absorbed into the crowns and rhizomes is sequestered below ground. Variable amounts of 15N were translocated from the shoots to the roots over the course of the growing season. Polar metabolites extracted from a diverse array of rhizomes were analyzed using GCMS. Data indicated that there was a significant shift in metabolite pools over the course of the growing season, and differences in the levels of specific metabolites could be linked to the progression of dormancy. Several metabolites that accumulate in dormant rhizomes were identified. Some of these metabolites could be potentially linked to winter-survival of switchgrass. Extensive high-throughput sequencing was conducted on crown and rhizome samples collected from field grown plants. Initial work was performed on a Roche 454 system. All later work was performed on an Illumina sequencing-by-synthesis system. Some of these datasets have been published as peer-reviewed papers, other data are currently being analyzed and being readied for publication. Objective 2 results: Genetically related but phenotypically divergent plants from an octaploid switchgrass population were grown in a replicated field nursery. Rhizomes were harvested at four different times over the course of the growing season from plants with high winter survival and those with lower winter survival. RNA-Seq was performed on harvested materials. Initial analysis suggests that plants with lowered winter survival experience a greater level of cellular stress in dormant tissues. This aspect of plant function is being probed in greater depth. Objective 3 results: A total of 592 individual clones with three clonal replications in a randomized complete block design from each of five populations used in Objective 1 studies were rated for heading date in 2012 and 2014, green-up day of year in 2013, anthesis date in 2012, and yield in 2012, they were also subjected to NIR spectroscopy to derive cell wall composition estimates based on prior NIR calibrations. Plants were genotyped via a genotyping by sequencing (GBS) approach from reduced representation libraries constructed with adaptors that identified each individual. Libraries generated with the restriction enzyme PstI and called SNPs using Samtools after alignment to version 1.1 of the switchgrass genome sequence. A total of approximately 40,000 SNPs were found. These were then further filtered to eliminate markers with a minor allele frequency of < 0.05. The results of population analysis using STRUCTURE with expected population sizes or cluster numbers (K), clearly shows the hybrid composition of the KxS population and discriminated easily between upland (Summer) and lowland (Kanlow) populations. Under an assumption of 5 distinct populations there were detectable differences in allele frequencies between subpopulations within the three Kanlow populations particularly with respect to Kanlow EM and Kanlow base. We detected 110 SNPs with an allele frequency difference of ≥ 0.2 between Kanlow EM and Kanlow base populations, while 120 SNPs showed an allele frequency difference of ≥ 0.15 between Kanlow N1 and Kanlow base populations. These data are being readied for publication.« less

Narratives of Self in Older Bilingual Adults Diagnosed with Alzheimer's Disease

ERIC Educational Resources Information Center

López de Victoria Rodríguez, Patria C.

2016-01-01

As the boom in the older adult population continues to grow, so too grows the number of persons suffering from cognitive diseases, such as dementia of the Alzheimer's type (DAT). Older Latinos diagnosed with the disease make up 4 percent (200,000) of the current population; however, little research on bilinguals with DAT has been carried out…

Older People as a Developing Market for Cultural Heritage Sites

ERIC Educational Resources Information Center

Hansen, Anna; Zipsane, Henrik

2014-01-01

Is it morally acceptable for the heritage sector to see the growing population of senior citizens as a developing market? Jamtli is an open air museum in the north of Sweden. The main target group is families with children, but an increasing number of activities for older adults are being offered. The growing population of older people is a…

Constructing Threats and a Need for Control: Textbook Descriptions of a Growing, Moving World Population

ERIC Educational Resources Information Center

Mikander, Pia; Holm, Gunilla

2014-01-01

The population of the world is growing and moving. The overwhelming majority of people are on the move inside their own country and mostly towards cities while a minority moves from non-Western areas to the West. In Finnish geography, history and social science school textbooks, this mobility tends to be depicted differently depending on whether…

Optometry services in Ontario: supply - and demand-side factors from 2011 to 2036.

PubMed

Leonard, Philip Sj; Sweetman, Arthur; Zhang, Xue Helen

2014-01-01

Optometric labour market projections are provided. First, population growth and ageing-based estimates of the rate of increase of eye-care services in Ontario from 2011 to 2$ are presented, holding the age-sex structure of utilization constant. Then, using data on the 2011 supply and working hours of Ontario's optometrists, the number of optometrists needed to keep the level of optometric services per age-sex-adjusted person comparable over time is estimated. The projections suggest that the number of Ontario optometrists should grow by approximately 30-40 full-time equivalents per year; to offset retirements and account for decreasing work hours, this suggests 77-90 new practitioners are required each year. However, in recent years, the number of Ontario optometrists has been growing faster than this, suggesting either that demand has exceeded supply and/or surpluses will accumulate if this trend continues. Copyright © 2014 Longwoods Publishing.

Structural change and higher educated labour in Indonesia.

PubMed

Pasay, N H

1990-12-01

This paper describes an impending shortage of higher-educated labor in Indonesia. Dynamic change is occurring in both Indonesia's population and economy. Its rapidly growing population demands annual national economic growth of 2.2% to avoid declining per capita output. Accordingly, investments have surged in banking and manufacturing industries as Indonesia undergoes structural change from an agricultural to service-based economy. Plagued by a majority of low productivity, elementary-level educated workers, increased productivity is called for to ensure continued development. As the age structural shift progresses, many of these workers will be absorbed in the services sector. Jobs exist requiring workers of all skill levels. This paper is mainly concerned, however, with higher-educated labor's failure to be oriented to the research and development required for sustained economic growth and development, and their entry into clerical positions potentially filled by less educated and less skilled labor. The services sector, particularly public services, is responsible for absorbing much of this labor. As professional, technical, and managerial capabilities and qualifications become increasingly needed in the near future as sector investments take effect, a shortage of higher-educated labor will become apparent. Policy makers are advised to anticipate these shortages and contemplate investments in human capital to facilitate a more smooth adjustment to structural change.

Genetic differentiation and phylogeographical structure of the Brachionus calyciflorus complex in eastern China.

PubMed

Xiang, Xian-Ling; Xi, Yi-Long; Wen, Xin-Li; Zhang, Gen; Wang, Jin-Xia; Hu, Ke

2011-07-01

Spatio-temporal patterns and processes of genetic differentiation in passively dispersing zooplankton are drawing much attention from both ecologists and evolutionary biologists. Two opposite phylogeographical scenarios have already been demonstrated in rotifers, which consist of high levels of genetic differentiation among populations even on small geographical scales on the one hand and the traditionally known cosmopolitanism that is associated with high levels of gene flow and long-distance dispersal via diapausing stages on the other hand. Here, we analysed the population genetic structure and the phylogeography of the Brachionus calyciflorus species complex in eastern China. By screening a total of 318 individuals from ten locations along a 2320-km gradient and analysing samples from two growing seasons, we aimed at focusing on both small- and large-scale patterns. We identified eight cryptic species and verified species status of two of these by sexual reproduction tests. Samples in summer and winter yielded different cryptic species. The distribution patterns of these genetically distinct cryptic species were diverse across eastern China, from full cosmopolitanism to local endemism. The two most abundant cryptic species BcWIII and BcSW showed a pattern of strong genetic differentiation among populations and no significant isolation by distance. Long-distance colonization, secondary contact and recent range expansion are probably responsible for the indistinct pattern of isolation by distance. Our results suggest that geographical distance is more important than temporal segregation across seasons in explaining population differentiation and the occurrence of cryptic species. We explain the current phylogeographical structure in the B. calyciflorus species complex by a combination of recent population expansion, restricted gene flow, priority effects and long-distance colonization. © 2011 Blackwell Publishing Ltd.

Effects of fungicides and biofungicides on population density and community structure of soil oribatid mites.

PubMed

Al-Assiuty, Abdel-Naieem I M; Khalil, Mohamed A; Ismail, Abdel-Wahab A; van Straalen, Nico M; Ageba, Mohamed F

2014-01-01

To compare the side-effects of chemical versus biofungicides on non-target organisms in agricultural soil, a study of population structure, spatial distribution and fecundity of oribatid mites, a diverse and species-rich group of microarthropods indicative of decomposer activity in soil was done. Plots laid out in agricultural fields of a research station in Egypt, were cultivated with cucumber and treated with two chemical fungicides: Ridomil Plus 50% wp (active ingredients=metalaxyl and copper oxychloride) and Dithane M-45 (active ingredient=mancozeb), and two biofungicides: Plant Guard (containing the antagonistic fungus Trichoderma harzianum) and Polyversum (containing the fungi-parasitic oomycete Pythium oligandrum). All treatments were done using both low-volume and high-volume spraying techniques to check whether any effects were dependent on the method of application. Oribatid mite communities were assessed from soil core samples collected during the growing season. Total abundance of oribatids was not different across the plots, but some species decreased in number, while one species increased. Species diversity and community equitability decreased with the application of chemical and biofungicides especially when using high-volume spraying. In control plots most oribatid species showed a significant degree of aggregation, which tended to decrease under fungicide treatment. Ridomil Plus, Plant Guard and Polyversum had a negative effect on the gravid/ungravid ratio of some species. Egg number averaged over the whole adult population was not directly related to the application of chemical and biofungicides but it showed a species-specific relationship with population density. In general biofungicides had a smaller effect on population size and community structure of oribatid mite species than chemical fungicides. The results indicate that biofungicides may be the preferred option when aiming to prevent side-effects on sensitive groups among the species-rich soil detritivore community. © 2013.

The impact of family formation change on the cognitive, social, and emotional well-being of the next generation.

PubMed

Amato, Paul R

2005-01-01

How have recent changes in U.S. family structure affected the cognitive, social, and emotional well-being of the nation's children? Paul Amato examines the effects of family formation on children and evaluates whether current marriage-promotion programs are likely to meet children's needs. Amato begins by investigating how children in households with both biological parents differ from children in households with only one biological parent. He shows that children growing up with two continuously married parents are less likely to experience a wide range of cognitive, emotional, and social problems, not only during childhood but also in adulthood. Although it is not possible to demonstrate that family structure causes these differences, studies using a variety of sophisticated statistical methods suggest that this is the case. Amato then asks what accounts for the differences between these two groups of children. He shows that compared with other children, those who grow up in stable, two-parent families have a higher standard of living, receive more effective parenting, experience more cooperative co-parenting, are emotionally closer to both parents, and are subjected to fewer stressful events and circumstances. Finally, Amato assesses how current marriage-promotion policies will affect the well-being of children. He finds that interventions that increase the share of children who grow up with both parents would improve the overall well-being of U.S. children only modestly, because children's social or emotional problems have many causes, of which family structure is but one. But interventions that lower only modestly the overall share of U.S. children experiencing various problems could nevertheless lower substantially the number of children experiencing them. Even a small decline in percentages, when multiplied by the many children in the population, is a substantial social benefit.

Advertisement call and genetic structure conservatism: good news for an endangered Neotropical frog

PubMed Central

Costa, William P.; Martins, Lucas B.; Nunes-de-Almeida, Carlos H. L.; Toledo, Luís Felipe

2016-01-01

Background: Many amphibian species are negatively affected by habitat change due to anthropogenic activities. Populations distributed over modified landscapes may be subject to local extinction or may be relegated to the remaining—likely isolated and possibly degraded—patches of available habitat. Isolation without gene flow could lead to variability in phenotypic traits owing to differences in local selective pressures such as environmental structure, microclimate, or site-specific species assemblages. Methods: Here, we tested the microevolution hypothesis by evaluating the acoustic parameters of 349 advertisement calls from 15 males from six populations of the endangered amphibian species Proceratophrys moratoi. In addition, we analyzed the genetic distances among populations and the genetic diversity with a haplotype network analysis. We performed cluster analysis on acoustic data based on the Bray-Curtis index of similarity, using the UPGMA method. We correlated acoustic dissimilarities (calculated by Euclidean distance) with geographical and genetic distances among populations. Results: Spectral traits of the advertisement call of P. moratoi presented lower coefficients of variation than did temporal traits, both within and among males. Cluster analyses placed individuals without congruence in population or geographical distance, but recovered the species topology in relation to sister species. The genetic distance among populations was low; it did not exceed 0.4% for the most distant populations, and was not correlated with acoustic distance. Discussion: Both acoustic features and genetic sequences are highly conserved, suggesting that populations could be connected by recent migrations, and that they are subject to stabilizing selective forces. Although further studies are required, these findings add to a growing body of literature suggesting that this species would be a good candidate for a reintroduction program without negative effects on communication or genetic impact. PMID:27190717

Advertisement call and genetic structure conservatism: good news for an endangered Neotropical frog.

PubMed

Forti, Lucas R; Costa, William P; Martins, Lucas B; Nunes-de-Almeida, Carlos H L; Toledo, Luís Felipe

2016-01-01

Many amphibian species are negatively affected by habitat change due to anthropogenic activities. Populations distributed over modified landscapes may be subject to local extinction or may be relegated to the remaining-likely isolated and possibly degraded-patches of available habitat. Isolation without gene flow could lead to variability in phenotypic traits owing to differences in local selective pressures such as environmental structure, microclimate, or site-specific species assemblages. Here, we tested the microevolution hypothesis by evaluating the acoustic parameters of 349 advertisement calls from 15 males from six populations of the endangered amphibian species Proceratophrys moratoi. In addition, we analyzed the genetic distances among populations and the genetic diversity with a haplotype network analysis. We performed cluster analysis on acoustic data based on the Bray-Curtis index of similarity, using the UPGMA method. We correlated acoustic dissimilarities (calculated by Euclidean distance) with geographical and genetic distances among populations. Spectral traits of the advertisement call of P. moratoi presented lower coefficients of variation than did temporal traits, both within and among males. Cluster analyses placed individuals without congruence in population or geographical distance, but recovered the species topology in relation to sister species. The genetic distance among populations was low; it did not exceed 0.4% for the most distant populations, and was not correlated with acoustic distance. Both acoustic features and genetic sequences are highly conserved, suggesting that populations could be connected by recent migrations, and that they are subject to stabilizing selective forces. Although further studies are required, these findings add to a growing body of literature suggesting that this species would be a good candidate for a reintroduction program without negative effects on communication or genetic impact.

Blended Design Approach of Long Span Structure and Malay Traditional Architecture

NASA Astrophysics Data System (ADS)

Sundari, Titin

2017-12-01

The growing population in the world is so fast, which is followed by the increasing need of some new and large activities. Architects face the problem on how to facilitate buildings with various activities such as for large meeting, conference, indoors gymnasium and sports, and many others. The long span structure of building is one of the solutions to solve that problem. Generally, large buildings which implemented this structure will look as a technological, modern and futuristic ones or even neo futuristic performance. But on the other hand, many people still want to enjoy the specific and unique senses of local traditional architecture. So is the Malay people who want an easy pleasant large facilities which can be fulfilled by implementing modern long span building structure technology. In the same time, their unique sense of Malay traditional architecture can still be maintained. To overcome this double problems of design, it needs a blended design approach of long span structure and Malay Traditional Architecture.

Division of Labor, Bet Hedging, and the Evolution of Mixed Biofilm Investment Strategies.

PubMed

Lowery, Nick Vallespir; McNally, Luke; Ratcliff, William C; Brown, Sam P

2017-08-08

Bacterial cells, like many other organisms, face a tradeoff between longevity and fecundity. Planktonic cells are fast growing and fragile, while biofilm cells are often slower growing but stress resistant. Here we ask why bacterial lineages invest simultaneously in both fast- and slow-growing types. We develop a population dynamic model of lineage expansion across a patchy environment and find that mixed investment is favored across a broad range of environmental conditions, even when transmission is entirely via biofilm cells. This mixed strategy is favored because of a division of labor where exponentially dividing planktonic cells can act as an engine for the production of future biofilm cells, which grow more slowly. We use experimental evolution to test our predictions and show that phenotypic heterogeneity is persistent even under selection for purely planktonic or purely biofilm transmission. Furthermore, simulations suggest that maintenance of a biofilm subpopulation serves as a cost-effective hedge against environmental uncertainty, which is also consistent with our experimental findings. IMPORTANCE Cell types specialized for survival have been observed and described within clonal bacterial populations for decades, but why are these specialists continually produced under benign conditions when such investment comes at a high reproductive cost? Conversely, when survival becomes an imperative, does it ever benefit the population to maintain a pool of rapidly growing but vulnerable planktonic cells? Using a combination of mathematical modeling, simulations, and experiments, we find that mixed investment strategies are favored over a broad range of environmental conditions and rely on a division of labor between cell types, where reproductive specialists amplify survival specialists, which can be transmitted through the environment with a limited mortality rate. We also show that survival specialists benefit rapidly growing populations by serving as a hedge against unpredictable changes in the environment. These results help to clarify the general evolutionary and ecological forces that can generate and maintain diverse subtypes within clonal bacterial populations. Copyright © 2017 Lowery et al.

The emergence of cooperation from a single cooperative mutant

NASA Astrophysics Data System (ADS)

Cremer, Jonas; Melbinger, Anna; Frey, Erwin

2012-02-01

Population structure is one central condition which promotes the stability of cooperation: If cooperators more likely interact with other cooperators (positive assortment), they keep most of their benefit for themselves and are less exploited by non-cooperators. However, positive assortment can only act successfully if cooperation is already well established in the population such that cooperative individuals can successfully assort. But how can cooperation emerge when starting with a single cooperative mutant? Here we study this issue for a generic situation of microbial systems where microbes regularly form new colonies and show strong population growth. We show how and when the dynamical interplay between colony formation, population growth and evolution within colonies can provoke the emergence of cooperation. In particular, the probability for a single cooperative mutant to succeed is robustly large when colony-formation is fast or comparable to the time-scale of growth within colonies; growth supports cooperation.[4pt] [1] A. Melbinger, J. Cremer, and E. Frey, Evolutionary game theory in growing populations, Phys. Rev. Lett. 105, 178101 (2010)[0pt] [2] J. Cremer, A. Melbinger, and E. Frey, Evolutionary and population dynamics: a coupled approach, arXiv:1108.2604

Projected effects of climate and development on California wildfire emissions through 2100.

PubMed

Hurteau, Matthew D; Westerling, Anthony L; Wiedinmyer, Christine; Bryant, Benjamin P

2014-02-18

Changing climatic conditions are influencing large wildfire frequency, a globally widespread disturbance that affects both human and natural systems. Understanding how climate change, population growth, and development patterns will affect the area burned by and emissions from wildfires and how populations will in turn be exposed to emissions is critical for climate change adaptation and mitigation planning. We quantified the effects of a range of population growth and development patterns in California on emission projections from large wildfires under six future climate scenarios. Here we show that end-of-century wildfire emissions are projected to increase by 19-101% (median increase 56%) above the baseline period (1961-1990) in California for a medium-high temperature scenario, with the largest emissions increases concentrated in northern California. In contrast to other measures of wildfire impacts previously studied (e.g., structural loss), projected population growth and development patterns are unlikely to substantially influence the amount of projected statewide wildfire emissions. However, increases in wildfire emissions due to climate change may have detrimental impacts on air quality and, combined with a growing population, may result in increased population exposure to unhealthy air pollutants.

Rapid urbanization and the growing threat of violence and conflict: a 21st century crisis.

PubMed

Patel, Ronak B; Burkle, Frederick M

2012-04-01

As the global population is concentrated into complex environments, rapid urbanization increases the threat of conflict and insecurity. Many fast-growing cities create conditions of significant disparities in standards of living, which set up a natural environment for conflict over resources. As urban slums become a haven for criminal elements, youth gangs, and the arms trade, they also create insecurity for much of the population. Specific populations, such as women, migrants, and refugees, bear the brunt of this lack of security, with significant impacts on their livelihoods, health, and access to basic services. This lack of security and violence also has great costs to the general population, both economic and social. Cities have increasingly become the battlefield of recent conflicts as they serve as the seats of power and gateways to resources. International agencies, non-governmental organizations, and policy-makers must act to stem this tide of growing urban insecurity. Protecting urban populations and preventing future conflict will require better urban planning, investment in livelihood programs for youth, cooperation with local communities, enhanced policing, and strengthening the capacity of judicial systems.

[A framework to support action in population mental health].

PubMed

Mantoura, Pascale; Roberge, Marie-Claude; Fournier, Louise

In Quebec, like elsewhere in the world, we are witnessing a growing concern for the population's mental health and for the importance of concentrating efforts on prevention and promotion. In this context, public health actors are invited to adopt a leadership role in advancing mental health promotion and mental disorder prevention goals, and establish the required partnerships with actors from the health and social services and from other sectors who are indispensable to the population mental health agenda. In Canada, public heath actors are not yet sufficiently supported in this role. They express the need to access structuring frameworks which can clarify their action in mental health. This article first presents the momentum for change at the policy level within the field of mental health. A framework to support population mental health action is then presented. The framework identifies the various dimensions underlying the promotion of population mental health as well as the reduction of mental health inequalities. The article finally illustrates how the application of a populational (the application of a populational responsibility perspective) responsibility perspective, as it is defined in the context of Quebec, facilitates the implementation of the various elements of this framework. In the end, public health actors are better equipped to situate their practice in favour of the population's mental health.

Technology-Based Literacy Instruction for English Language Learners

ERIC Educational Resources Information Center

White, Erin L.; Gillard, Sharlett

2011-01-01

There is a growing need to implement an alternative and viable solution in U.S. K-12 schools that will address the ever-growing gap that the rapidly growing English language learner (ELL) population presents. This article examines various technology-based solutions, and their potential impact. The systematic implementation of these…

Expanding the Learning Experience beyond the Classroom Walls for Developmental Immigrant Students

ERIC Educational Resources Information Center

Goldschmidt, Myra M.; Ousey, Debbie Lamb; Brown, Christine

2012-01-01

Developmental immigrant students are a growing phenomenon in the United States, a growing population in higher education, and a growing presence in undergraduate classes, and like their mainstream developmental counterparts, many are academically underprepared for the rigors of college (Goldschmidt & Ousey, 2011), sometimes prolonging, or even…

Percutaneous Coronary and Structural Interventions in Women. A Position Statement from the EAPCI Women Committee.

PubMed

Chieffo, Alaide; Buchanan, Gill Louise; Mehilli, Julinda; Capodanno, Davide; Kunadian, Vijay; Petronio, Anna Sonia; Mikhail, Ghada W; Capranzano, Piera; Gonzal, Nieves; Karam, Nicole; Manzo-Silberman, Stéphane; Schüpke, Stefanie; Byrne, Robert A; Capretti, Giuliana; Appelman, Yolande; Morice, Marie-Claude; Presbitero, Patrizia; Radu, Maria; Mauri, Josepa

2018-05-22

Several expert documents on sex-based differences in interventional outcomes are now available, however this is the first position paper from the EAPCI Women Committee discussing the potential influence of sex in the percutaneous treatment of coronary and structural heart disease. Despite the misconception that coronary artery disease is a 'man's disease', contemporary data shows a growing incidence in women. However, women are under-represented in randomised coronary clinical trials (~25%). The generalisation of such studies is therefore problematic in decision-making for females undergoing coronary intervention. Differences in pathophysiology between sexes exist, highlighting the need for greater awareness amongst healthcare professionals to enable best evidence-based therapies for women as well as for men. Reassuringly, women represent half of the population included in transcatheter aortic valve implantation clinical trials and may actually benefit more. Growing evidence is also emerging for other interventional atrial procedures which may well be advantageous to women. Awareness of sex disparities is increasing, and we must all work collaboratively within our profession to ensure we provide effective care for all patients with heart disease. The EAPCI Women Committee aim to highlight such issues through this position paper and through visibility within the interventional community.

Cooperative networks overcoming defectors by social influence

NASA Astrophysics Data System (ADS)

Gomez Portillo, Ignacio

2014-01-01

We address the cooperation problem in structured populations by considering the prisoner’s dilemma game as a metaphor of the social interactions between individuals with imitation capacity. We present a new strategy update rule called democratic weighted update where the individual’s behavior is socially influenced by each one of their neighbors. In particular, the capacity of an individual to socially influence other ones is proportional to its accumulated payoff. When in a neighborhood there are cooperators and defectors, the focal player is contradictorily influenced by them and, therefore, the effective social influence is given by the difference of the accumulated payoff of each strategy in its neighborhood. First, by considering the growing process of the network and neglecting mutations, we show the evolution of highly cooperative systems. Then, we broadly show that the social influence allows to overcome the emergence of defectors into highly cooperative systems. In this way, we conclude that in a structured system formed by a growing process, the cooperation evolves if the individuals have an imitation capacity socially influenced by each one of their neighbors. Therefore, here we present a theoretical solution of the cooperation problem among genetically unrelated individuals.

Widespread Secondary Contact and New Glacial Refugia in the Halophilic Rotifer Brachionus plicatilis in the Iberian Peninsula

PubMed Central

Campillo, Sergi; Serra, Manuel; Carmona, María José; Gómez, Africa

2011-01-01

Small aquatic organisms harbour deep phylogeographic patterns and highly structured populations even at local scales. These patterns indicate restricted gene flow, despite these organisms' high dispersal abilities, and have been explained by a combination of (1) strong founder effects due to rapidly growing populations and very large population sizes, and (2) the development of diapausing egg banks and local adaptation, resulting in low effective gene flow, what is known as the Monopolization hypothesis. In this study, we build up on our understanding of the mitochondrial phylogeography of the halophilic rotifer Brachionus plicatilis in the Iberian Peninsula by both increasing the number of sampled ponds in areas where secondary contact is likely and doubling sample sizes. We analyzed partial mitochondrial sequences of 252 individuals. We found two deep mitochondrial DNA lineages differing in both their genetic diversity and the complexity of their phylogeographic structure. Our analyses suggest that several events of secondary contact between clades occurred after their expansion from glacial refugia. We found a pattern of isolation-by-distance, which we interpret as being the result of historical colonization events. We propose the existence of at least one glacial refugium in the SE of the Iberian Peninsula. Our findings challenge predictions of the Monopolization hypothesis, since coexistence (i.e., secondary contact) of divergent lineages in some ponds in the Iberian Peninsula is common. Our results indicate that phylogeographic structures in small organisms can be very complex and that gene flow between diverse lineages after population establishment can indeed occur. PMID:21698199

Widespread secondary contact and new glacial refugia in the halophilic rotifer Brachionus plicatilis in the Iberian Peninsula.

PubMed

Campillo, Sergi; Serra, Manuel; Carmona, María José; Gómez, Africa

2011-01-01

Small aquatic organisms harbour deep phylogeographic patterns and highly structured populations even at local scales. These patterns indicate restricted gene flow, despite these organisms' high dispersal abilities, and have been explained by a combination of (1) strong founder effects due to rapidly growing populations and very large population sizes, and (2) the development of diapausing egg banks and local adaptation, resulting in low effective gene flow, what is known as the Monopolization hypothesis. In this study, we build up on our understanding of the mitochondrial phylogeography of the halophilic rotifer Brachionus plicatilis in the Iberian Peninsula by both increasing the number of sampled ponds in areas where secondary contact is likely and doubling sample sizes. We analyzed partial mitochondrial sequences of 252 individuals. We found two deep mitochondrial DNA lineages differing in both their genetic diversity and the complexity of their phylogeographic structure. Our analyses suggest that several events of secondary contact between clades occurred after their expansion from glacial refugia. We found a pattern of isolation-by-distance, which we interpret as being the result of historical colonization events. We propose the existence of at least one glacial refugium in the SE of the Iberian Peninsula. Our findings challenge predictions of the Monopolization hypothesis, since coexistence (i.e., secondary contact) of divergent lineages in some ponds in the Iberian Peninsula is common. Our results indicate that phylogeographic structures in small organisms can be very complex and that gene flow between diverse lineages after population establishment can indeed occur.

Genetic and Metabolite Diversity of Sardinian Populations of Helichrysum italicum

PubMed Central

Melito, Sara; Sias, Angela; Petretto, Giacomo L.; Chessa, Mario; Pintore, Giorgio; Porceddu, Andrea

2013-01-01

Background Helichrysum italicum (Asteraceae) is a small shrub endemic to the Mediterranean Basin, growing in fragmented and diverse habitats. The species has attracted attention due to its secondary metabolite content, but little effort has as yet been dedicated to assessing the genetic and metabolite diversity present in these populations. Here, we describe the diversity of 50 H. italicum populations collected from a range of habitats in Sardinia. Methods H. italicum plants were AFLP fingerprinted and the composition of their leaf essential oil characterized by GC-MS. The relationships between the genetic structure of the populations, soil, habitat and climatic variables and the essential oil chemotypes present were evaluated using Bayesian clustering, contingency analyses and AMOVA. Key results The Sardinian germplasm could be partitioned into two AFLP-based clades. Populations collected from the southwestern region constituted a homogeneous group which remained virtually intact even at high levels of K. The second, much larger clade was more diverse. A positive correlation between genetic diversity and elevation suggested the action of natural purifying selection. Four main classes of compounds were identified among the essential oils, namely monoterpenes, oxygenated monoterpenes, sesquiterpenes and oxygenated sesquiterpenes. Oxygenated monoterpene levels were significantly correlated with the AFLP-based clade structure, suggesting a correspondence between gene pool and chemical diversity. Conclusions The results suggest an association between chemotype, genetic diversity and collection location which is relevant for the planning of future collections aimed at identifying valuable sources of essential oil. PMID:24260149

In situ genetic differentiation in a Hispaniolan lizard (Ameiva chrysolaema): a multilocus perspective.

PubMed

Gifford, Matthew E; Larson, Allan

2008-10-01

A previous phylogeographic study of mitochondrial haplotypes for the Hispaniolan lizard Ameiva chrysolaema revealed deep genetic structure associated with seawater inundation during the late Pliocene/early Pleistocene and evidence of subsequent population expansion into formerly inundated areas. We revisit hypotheses generated by our previous study using increased geographic sampling of populations and analysis of three nuclear markers (alpha-enolase intron 8, alpha-cardiac-actin intron 4, and beta-actin intron 3) in addition to mitochondrial haplotypes (ND2). Large genetic discontinuities correspond spatially and temporally with historical barriers to gene flow (sea inundations). NCPA cross-validation analysis and Bayesian multilocus analyses of divergence times (IMa and MCMCcoal) reveal two separate episodes of fragmentation associated with Pliocene and Pleistocene sea inundations, separating the species into historically separate Northern, East-Central, West-Central, and Southern population lineages. Multilocus Bayesian analysis using IMa indicates asymmetrical migration from the East-Central to the West-Central populations following secondary contact, consistent with expectations from the more pervasive sea inundation in the western region. The West-Central lineage has a genetic signature of population growth consistent with the expectation of geographic expansion into formerly inundated areas. Within each lineage, significant spatial genetic structure indicates isolation by distance at comparable temporal scales. This study adds to the growing body of evidence that vicariant speciation may be the prevailing source of lineage accumulation on oceanic islands. Thus, prior theories of island biogeography generally underestimate the role and temporal scale of intra-island vicariant processes.

Mutation independently affects reproductive traits and dauer larvae development in mutation accumulation lines of Caenorhabditis elegans.

PubMed

Hills, Arthur J; Green, James W M; Harvey, Simon C

2017-11-01

Developmental decisions are important in organismal fitness. For the nematode Caenorhabditis elegans, which is naturally found in the ephemeral food patches formed by rotting plant material, correctly committing to dauer or non-dauer larval development is key to genotype survival. To investigate the link between reproductive traits, which will determine how populations grow, and dauer larvae formation, we have analysed these traits in mutation accumulation lines of C. elegans. We find that reproductive traits of individual worms-the total number of progeny and the timing of progeny production-are highly correlated with the population size observed in growing populations. In contrast, we find no relationship between reproduction traits and the number of dauer larvae observed in growing populations. We also do not observe a mutational bias in dauer larvae formation. These results indicate that the control of dauer larvae formation is distinct from the control of reproduction and that differences in dauer larvae formation can evolve rapidly.

Life history and viability of a long-lived marine invertebrate: the octocoral Paramuricea clavata.

PubMed

Linares, Cristina; Doak, Daniel F; Coma, Rafel; Díaz, David; Zabala, Mikel

2007-04-01

The red gorgonian Paramuricea clavata is a long-lived, slow-growing sessile invertebrate of ecological and conservation importance in the northwestern Mediterranean Sea. We develop a series of size-based matrix models for two Paramuricea clavata populations. These models were used to estimate basic life history traits for this species and to evaluate the viability of the red gorgonian populations we studied. As for many other slow-growing species, sensitivity and elasticity analysis demonstrate that gorgonian population growth is far more sensitive to changes in survival rates than to growth, shrinkage, or reproductive rates. The slow growth and low mortality of red gorgonians results in low damping ratios, indicating slow convergence to stable size structures (at least 50 years). The stable distributions predicted by the model did not differ from the observed ones. However, our simulations point out the fragility of this species, showing both populations in decline and high risk of extinction over moderate time horizons. These declines appear to be related to a recent increase in anthropogenic disturbances. Relative to their life span, the values of recruitment elasticity for Paramuricea clavata are lower than those reported for other marine organisms but are similar to those reported for some long-lived plants. These values and the delayed age of sexual maturity, in combination with the longevity of the species, show a clear fecundity/mortality trade-off. Full demographic studies of sessile marine species are quite scarce but can provide insight into population dynamics and life history patterns for these difficult and under-studied species. While our work shows clear results for the red gorgonian, the variability in some of our estimates suggest that future work should include data collection over longer temporal and spatial scales to better understand the long-term effects of natural and anthropogenic disturbances on red gorgonian populations.

The Spectrum of Epidemiology Underlying Sudden Cardiac Death

PubMed Central

Hayashi, Meiso; Shimizu, Wataru; Albert, Christine M.

2015-01-01

Sudden cardiac death (SCD) from cardiac arrest is a major international public health problem accounting for an estimated 15–20% of all deaths. Although resuscitation rates are generally improving throughout the world, the majority of individuals who suffer a sudden cardiac arrest will not survive. SCD most often develops in older adults with acquired structural heart disease, but it also rarely occurs in the young, where it is more commonly due to inherited disorders. Coronary heart disease (CHD) is known to be the most common pathology underlying SCD, followed by cardiomyopathies, inherited arrhythmia syndromes, and valvular heart disease. Over the past three decades, declines in SCD rates have not been as steep as for other causes of CHD deaths, and there is a growing fraction of SCDs not due to CHD and/or ventricular arrhythmias, particularly among certain subsets of the population. The growing heterogeneity of the pathologies and mechanisms underlying SCD present major challenges for SCD prevention, which are magnified further by a frequent lack of recognition of the underlying cardiac condition prior to death. Multifaceted preventative approaches, which address risk factors in seemingly low risk and known high-risk populations will be required to decrease the burden of SCD. In this Compendium, we review the wide-ranging spectrum of epidemiology underlying SCD within both the general population and in high-risk subsets with established cardiac disease placing an emphasis on recent global trends, remaining uncertainties, and potential targeted preventive strategies. PMID:26044246

Relative contributions of neutral and non-neutral genetic differentiation to inform conservation of steelhead trout across highly variable landscapes

PubMed Central

Matala, Andrew P; Ackerman, Michael W; Campbell, Matthew R; Narum, Shawn R

2014-01-01

Mounting evidence of climatic effects on riverine environments and adaptive responses of fishes have elicited growing conservation concerns. Measures to rectify population declines include assessment of local extinction risk, population ecology, viability, and genetic differentiation. While conservation planning has been largely informed by neutral genetic structure, there has been a dearth of critical information regarding the role of non-neutral or functional genetic variation. We evaluated genetic variation among steelhead trout of the Columbia River Basin, which supports diverse populations distributed among dynamic landscapes. We categorized 188 SNP loci as either putatively neutral or candidates for divergent selection (non-neutral) using a multitest association approach. Neutral variation distinguished lineages and defined broad-scale population structure consistent with previous studies, but fine-scale resolution was also detected at levels not previously observed. Within distinct coastal and inland lineages, we identified nine and 22 candidate loci commonly associated with precipitation or temperature variables and putatively under divergent selection. Observed patterns of non-neutral variation suggest overall climate is likely to shape local adaptation (e.g., potential rapid evolution) of steelhead trout in the Columbia River region. Broad geographic patterns of neutral and non-neutral variation demonstrated here can be used to accommodate priorities for regional management and inform long-term conservation of this species. PMID:25067950

Populations of subplate and interstitial neurons in fetal and adult human telencephalon.

PubMed

Judaš, Miloš; Sedmak, Goran; Pletikos, Mihovil; Jovanov-Milošević, Nataša

2010-10-01

In the adult human telencephalon, subcortical (gyral) white matter contains a special population of interstitial neurons considered to be surviving descendants of fetal subplate neurons [Kostovic & Rakic (1980) Cytology and the time of origin of interstitial neurons in the white matter in infant and adult human and monkey telencephalon. J Neurocytol9, 219]. We designate this population of cells as superficial (gyral) interstitial neurons and describe their morphology and distribution in the postnatal and adult human cerebrum. Human fetal subplate neurons cannot be regarded as interstitial, because the subplate zone is an essential part of the fetal cortex, the major site of synaptogenesis and the 'waiting' compartment for growing cortical afferents, and contains both projection neurons and interneurons with distinct input-output connectivity. However, although the subplate zone is a transient fetal structure, many subplate neurons survive postnatally as superficial (gyral) interstitial neurons. The fetal white matter is represented by the intermediate zone and well-defined deep periventricular tracts of growing axons, such as the corpus callosum, anterior commissure, internal and external capsule, and the fountainhead of the corona radiata. These tracts gradually occupy the territory of transient fetal subventricular and ventricular zones.The human fetal white matter also contains distinct populations of deep fetal interstitial neurons, which, by virtue of their location, morphology, molecular phenotypes and advanced level of dendritic maturation, remain distinct from subplate neurons and neurons in adjacent structures (e.g. basal ganglia, basal forebrain). We describe the morphological, histochemical (nicotinamide-adenine dinucleotide phosphate-diaphorase) and immunocytochemical (neuron-specific nuclear protein, microtubule-associated protein-2, calbindin, calretinin, neuropeptide Y) features of both deep fetal interstitial neurons and deep (periventricular) interstitial neurons in the postnatal and adult deep cerebral white matter (i.e. corpus callosum, anterior commissure, internal and external capsule and the corona radiata/centrum semiovale). Although these deep interstitial neurons are poorly developed or absent in the brains of rodents, they represent a prominent feature of the significantly enlarged white matter of human and non-human primate brains. © 2010 The Authors. Journal of Anatomy © 2010 Anatomical Society of Great Britain and Ireland.

Future directions of ecosystem science

USGS Publications Warehouse

Baron, Jill S.; Galvin, Kathleen A.

1990-01-01

Scientific knowledge about ecosystem structure and function has expanded greatly during the past few decades. Terrestrial and aquatic nutrient cycling, ecosystem energetics, population dynamics, belowground processes, and food webs have been studied at the plot, stand, watershed, and landscape levels at many locations around the globe. Ideas about terrestrial-atmospheric interactions and human interference in these processes have changed dramatically. There is new appreciation of the need to incorporate into ecosystem studies the interactions between human populations and the ecosystem, not only because humans affect ecosystem processes, but because these systems support human populations (Glantz 1988, Holden 1988, Parry et al. 1988, WCED 1987). Recent advances in ecosystem science are due, in part, to technological improvements in computing power, new laboratory and field physical and chemical analytical techniques, and satellite imagery for remote sensing of Earth's structure and dynamics. Modeling and geographic information systems have provided the capability for integrating multiple data sets with process simulations to generate hypotheses about regional ecosystem function. Concurrent with these scientific developments has been a growing concern about the links between the health of the environment and world-wide industrial, land, and resource-management practices. Environmental damage at the local level was widely recognized in the 1960s, prompting the environmental movement of that decade. Regional environmental problems with multiple effects and politically difficult solutions have been perceived more recently; the issue of acidic deposition provides an example of such a second-generation concern (Clark and Holling 1985). Today there is a growing awareness of global-scale environmental degradation brought about by the combined actions of all peoples on Earth (Clark 1989, Woodmansee et al. 1988). The three levels of environmental concern--local, regional, and global--have not replaced one another (Clark and Holling 1985). Instead, the effects are superimposed, creating what some perceive as impending global environmental crisis (Clark 1989, MacNeill 1989, WCED 1987). Public demands are developing for economic, political, social, and environmental efforts directed toward creating a state of global sustainability.

An Investigation of the Relationships Between Reading Speed and Paper Hue Intensity, Age and Gender

ERIC Educational Resources Information Center

Ekstrom, Ireta

2004-01-01

Due in part to health care improvements and the post World War Two Baby Boom, (Siegel, 1972), the population of older adults is growing and will continue to grow. By 2030 approximately 20 percent of the U.S. population will be over age 65 (Verma, 1989). By attending to readability (the ease of reading a printed page) and legibility (the speed with…

Aging in the United States: Opportunities and Challenges for Otolaryngology-Head and Neck Surgery.

PubMed

Chiu, Brandon L; Pinto, Jayant M

2018-05-17

The number of Americans over the age of 65 has been growing much faster than the overall population's growth rate. These changes can be largely attributed to the improvement in life expectancy. This demographic shift yields a unique and exciting opportunity to provide both expedient and cost-efficient care to a growing patient population. Copyright © 2018 Elsevier Inc. All rights reserved.

Hispanic Student Participation and Success in Developmental Education. White Paper Prepared for the Hispanic Association of Colleges and Universities

ERIC Educational Resources Information Center

Nora, Amaury; Crisp, Gloria

2012-01-01

As has been known for some time now, the Hispanic population is projected to grow to 25% of the total United States population by 2050. In spite of this growth, substantial disparities exist between Hispanics and other ethnic groups in terms of bachelor's degree attainment (Llagas & Snyder, 2003). In response, there is a rapidly growing body of…

Wild cricket social networks show stability across generations.

PubMed

Fisher, David N; Rodríguez-Muñoz, Rolando; Tregenza, Tom

2016-07-27

A central part of an animal's environment is its interactions with conspecifics. There has been growing interest in the potential to capture these interactions in the form of a social network. Such networks can then be used to examine how relationships among individuals affect ecological and evolutionary processes. However, in the context of selection and evolution, the utility of this approach relies on social network structures persisting across generations. This is an assumption that has been difficult to test because networks spanning multiple generations have not been available. We constructed social networks for six annual generations over a period of eight years for a wild population of the cricket Gryllus campestris. Through the use of exponential random graph models (ERGMs), we found that the networks in any given year were able to predict the structure of networks in other years for some network characteristics. The capacity of a network model of any given year to predict the networks of other years did not depend on how far apart those other years were in time. Instead, the capacity of a network model to predict the structure of a network in another year depended on the similarity in population size between those years. Our results indicate that cricket social network structure resists the turnover of individuals and is stable across generations. This would allow evolutionary processes that rely on network structure to take place. The influence of network size may indicate that scaling up findings on social behaviour from small populations to larger ones will be difficult. Our study also illustrates the utility of ERGMs for comparing networks, a task for which an effective approach has been elusive.

Structural and functional imaging studies in chronic cannabis users: a systematic review of adolescent and adult findings.

PubMed

Batalla, Albert; Bhattacharyya, Sagnik; Yücel, Murat; Fusar-Poli, Paolo; Crippa, Jose Alexandre; Nogué, Santiago; Torrens, Marta; Pujol, Jesús; Farré, Magí; Martin-Santos, Rocio

2013-01-01

The growing concern about cannabis use, the most commonly used illicit drug worldwide, has led to a significant increase in the number of human studies using neuroimaging techniques to determine the effect of cannabis on brain structure and function. We conducted a systematic review to assess the evidence of the impact of chronic cannabis use on brain structure and function in adults and adolescents. Papers published until August 2012 were included from EMBASE, Medline, PubMed and LILACS databases following a comprehensive search strategy and pre-determined set of criteria for article selection. Only neuroimaging studies involving chronic cannabis users with a matched control group were considered. One hundred and forty-two studies were identified, of which 43 met the established criteria. Eight studies were in adolescent population. Neuroimaging studies provide evidence of morphological brain alterations in both population groups, particularly in the medial temporal and frontal cortices, as well as the cerebellum. These effects may be related to the amount of cannabis exposure. Functional neuroimaging studies suggest different patterns of resting global and brain activity during the performance of several cognitive tasks both in adolescents and adults, which may indicate compensatory effects in response to chronic cannabis exposure. However, the results pointed out methodological limitations of the work conducted to date and considerable heterogeneity in the findings. Chronic cannabis use may alter brain structure and function in adult and adolescent population. Further studies should consider the use of convergent methodology, prospective large samples involving adolescent to adulthood subjects, and data-sharing initiatives.

Gene flow and pathogen transmission among bobcats (Lynx rufus) in a fragmented urban landscape

USGS Publications Warehouse

Lee, Justin S.; Ruell, Emily W.; Boydston, Erin E.; Lyren, Lisa M.; Alonso, Robert S.; Troyer, Jennifer L.; Crooks, Kevin R.; VandeWoude, Sue

2012-01-01

Urbanization can result in the fragmentation of once contiguous natural landscapes into a patchy habitat interspersed within a growing urban matrix. Animals living in fragmented landscapes often have reduced movement among habitat patches because of avoidance of intervening human development, which potentially leads to both reduced gene flow and pathogen transmission between patches. Mammalian carnivores with large home ranges, such as bobcats (Lynx rufus), may be particularly sensitive to habitat fragmentation. We performed genetic analyses on bobcats and their directly transmitted viral pathogen, feline immunodeficiency virus (FIV), to investigate the effects of urbanization on bobcat movement. We predicted that urban development, including major freeways, would limit bobcat movement and result in genetically structured host and pathogen populations. We analysed molecular markers from 106 bobcats and 19 FIV isolates from seropositive animals in urban southern California. Our findings indicate that reduced gene flow between two primary habitat patches has resulted in genetically distinct bobcat subpopulations separated by urban development including a major highway. However, the distribution of genetic diversity among FIV isolates determined through phylogenetic analyses indicates that pathogen genotypes are less spatially structured--exhibiting a more even distribution between habitat fragments. We conclude that the types of movement and contact sufficient for disease transmission occur with enough frequency to preclude structuring among the viral population, but that the bobcat population is structured owing to low levels of effective bobcat migration resulting in gene flow. We illustrate the utility in using multiple molecular markers that differentially detect movement and gene flow between subpopulations when assessing connectivity.

Structural and Functional Imaging Studies in Chronic Cannabis Users: A Systematic Review of Adolescent and Adult Findings

PubMed Central

Batalla, Albert; Bhattacharyya, Sagnik; Yücel, Murat; Fusar-Poli, Paolo; Crippa, Jose Alexandre; Nogué, Santiago; Torrens, Marta; Pujol, Jesús; Farré, Magí; Martin-Santos, Rocio

2013-01-01

Background The growing concern about cannabis use, the most commonly used illicit drug worldwide, has led to a significant increase in the number of human studies using neuroimaging techniques to determine the effect of cannabis on brain structure and function. We conducted a systematic review to assess the evidence of the impact of chronic cannabis use on brain structure and function in adults and adolescents. Methods Papers published until August 2012 were included from EMBASE, Medline, PubMed and LILACS databases following a comprehensive search strategy and pre-determined set of criteria for article selection. Only neuroimaging studies involving chronic cannabis users with a matched control group were considered. Results One hundred and forty-two studies were identified, of which 43 met the established criteria. Eight studies were in adolescent population. Neuroimaging studies provide evidence of morphological brain alterations in both population groups, particularly in the medial temporal and frontal cortices, as well as the cerebellum. These effects may be related to the amount of cannabis exposure. Functional neuroimaging studies suggest different patterns of resting global and brain activity during the performance of several cognitive tasks both in adolescents and adults, which may indicate compensatory effects in response to chronic cannabis exposure. Limitations However, the results pointed out methodological limitations of the work conducted to date and considerable heterogeneity in the findings. Conclusion Chronic cannabis use may alter brain structure and function in adult and adolescent population. Further studies should consider the use of convergent methodology, prospective large samples involving adolescent to adulthood subjects, and data-sharing initiatives. PMID:23390554

The biogeodynamics of microbial landscapes

NASA Astrophysics Data System (ADS)

Battin, T. J.; Hödl, I.; Bertuzzo, E.; Mari, L.; Suweis, S. S.; Rinaldo, A.

2011-12-01

Spatial configuration is fundamental in defining the structural and functional properties of biological systems. Biofilms, surface-attached and matrix-enclosed microorganisms, are a striking example of spatial organisation. Coupled biotic and abiotic processes shape the spatial organisation across scales of the landscapes formed by these benthic biofilms in streams and rivers. Experimenting with such biofilms in streams, we found that, depending on the streambed topography and the related hydrodynamic microenvironment, biofilm landscapes form increasingly diverging spatial patterns as they grow. Strikingly, however, cluster size distributions tend to converge even in contrasting hydrodynamic microenvironments. To reproduce the observed cluster size distributions we used a continuous, size-structured population model. The model accounts for the formation, growth, erosion and merging of biofilm clusters. Our results suggest not only that hydrodynamic forcing induce the diverging patterning of the microbial landscape, but also that microorganisms have developed strategies to equally exploit spatial resources independently of the physical structure of the microenvironment where they live.

The convergence of maturational change and structural covariance in human cortical networks.

PubMed

Alexander-Bloch, Aaron; Raznahan, Armin; Bullmore, Ed; Giedd, Jay

2013-02-13

Large-scale covariance of cortical thickness or volume in distributed brain regions has been consistently reported by human neuroimaging studies. The mechanism of this population covariance of regional cortical anatomy has been hypothetically related to synchronized maturational changes in anatomically connected neuronal populations. Brain regions that grow together, i.e., increase or decrease in volume at the same rate over the course of years in the same individual, are thus expected to demonstrate strong structural covariance or anatomical connectivity across individuals. To test this prediction, we used a structural MRI dataset on healthy young people (N = 108; aged 9-22 years at enrollment), comprising 3-6 longitudinal scans on each participant over 6-12 years of follow-up. At each of 360 regional nodes, and for each participant, we estimated the following: (1) the cortical thickness in the median scan and (2) the linear rate of change in cortical thickness over years of serial scanning. We constructed structural and maturational association matrices and networks from these measurements. Both structural and maturational networks shared similar global and nodal topological properties, as well as mesoscopic features including a modular community structure, a relatively small number of highly connected hub regions, and a bias toward short distance connections. Using resting-state functional magnetic resonance imaging data on a subset of the sample (N = 32), we also demonstrated that functional connectivity and network organization was somewhat predictable by structural/maturational networks but demonstrated a stronger bias toward short distance connections and greater topological segregation. Brain structural covariance networks are likely to reflect synchronized developmental change in distributed cortical regions.

Disease invasion risk in a growing population.

PubMed

Yuan, Sanling; van den Driessche, P; Willeboordse, Frederick H; Shuai, Zhisheng; Ma, Junling

2016-09-01

The spread of an infectious disease may depend on the population size. For simplicity, classic epidemic models assume homogeneous mixing, usually standard incidence or mass action. For standard incidence, the contact rate between any pair of individuals is inversely proportional to the population size, and so the basic reproduction number (and thus the initial exponential growth rate of the disease) is independent of the population size. For mass action, this contact rate remains constant, predicting that the basic reproduction number increases linearly with the population size, meaning that disease invasion is easiest when the population is largest. In this paper, we show that neither of these may be true on a slowly evolving contact network: the basic reproduction number of a short epidemic can reach its maximum while the population is still growing. The basic reproduction number is proportional to the spectral radius of a contact matrix, which is shown numerically to be well approximated by the average excess degree of the contact network. We base our analysis on modeling the dynamics of the average excess degree of a random contact network with constant population input, proportional deaths, and preferential attachment for contacts brought in by incoming individuals (i.e., individuals with more contacts attract more incoming contacts). In addition, we show that our result also holds for uniform attachment of incoming contacts (i.e., every individual has the same chance of attracting incoming contacts), and much more general population dynamics. Our results show that a disease spreading in a growing population may evade control if disease control planning is based on the basic reproduction number at maximum population size.

Taking care of my baby: mexican-american mothers in the neonatal intensive care unit.

PubMed

Cleveland, Lisa M; Horner, Sharon D

2012-01-01

The admission of an infant to the neonatal intensive care unit (NICU) can produce significant stress for mothers and may contribute to a difficult transition following discharge. Past research has primarily focused on Caucasian women. Mexican-Americans are the fastest growing ethnic population in the U.S. with the highest fertility rate; therefore, the purpose of this grounded theory study was to gain a better understanding of the NICU experience for Mexican-American mothers. Fifteen women were recruited and data were collected through semi-structured interviews. A theoretical model, taking care of my baby, was developed. The mothers' experiences began with the unexpected event of having an infant admitted to the NICU and played out in a context that fluctuated between being supportive (making meaningful connections) or inhibitive (struggling to mother). The women developed strategies to help them take care of their babies during the NICU stay: balancing responsibilities, leaving part of me with my baby, and watching over. The process concluded in one of two ways: bringing my baby home or losing my baby. These findings offer insight for neonatal nurses who provide care for Mexican-American NICU mothers and may help inform their practice. Further research is needed with this growing population to ensure supportive nursing care and influence positive outcomes.

Urban Household Carbon Emission and Contributing Factors in the Yangtze River Delta, China

PubMed Central

Xu, Xibao; Tan, Yan; Chen, Shuang; Yang, Guishan; Su, Weizhong

2015-01-01

Carbon reduction at the household level is an integral part of carbon mitigation. This study analyses the characteristics, effects, contributing factors and policies for urban household carbon emissions in the Yangtze River Delta of China. Primary data was collected through structured questionnaire surveys in three cities in the region – Nanjing, Ningbo, and Changzhou in 2011. The survey data was first used to estimate the magnitude of household carbon emissions in different urban contexts. It then examined how, and to what extent, each set of demographic, economic, behavioral/cognitive and spatial factors influence carbon emissions at the household level. The average of urban household carbon emissions in the region was estimated to be 5.96 tonnes CO2 in 2010. Energy consumption, daily commuting, garbage disposal and long-distance travel accounted for 51.2%, 21.3%, 16.0% and 11.5% of the total emission, respectively. Regulating rapidly growing car-holdings of urban households, stabilizing population growth, and transiting residents’ low-carbon awareness to household behavior in energy saving and other spheres of consumption in the context of rapid population aging and the growing middle income class are suggested as critical measures for carbon mitigation among urban households in the Yangtze River Delta. PMID:25884853

Population demography of an endangered lizard, the Blue Mountains Water Skink

PubMed Central

2013-01-01

Background Information on the age structure within populations of an endangered species can facilitate effective management. The Blue Mountains Water Skink (Eulamprus leuraensis) is a viviparous scincid lizard that is restricted to < 40 isolated montane swamps in south-eastern Australia. We used skeletochronology of phalanges (corroborated by mark-recapture data) to estimate ages of 222 individuals from 13 populations. Results These lizards grow rapidly, from neonatal size (30 mm snout-vent length) to adult size (about 70 mm SVL) within two to three years. Fecundity is low (mean 2.9 offspring per litter) and is affected by maternal body length and age. Offspring quality may decline with maternal age, based upon captive-born neonates (older females gave birth to slower offspring). In contrast to its broadly sympatric (and abundant) congener E. tympanum, E. leuraensis is short-lived (maximum 6 years, vs 15 years for E. tympanum). Litter size and offspring size are similar in the two species, but female E. leuraensis reproduce annually whereas many E. tympanum produce litters biennially. Thus, a low survival rate (rather than delayed maturation or low annual fecundity) is the key reason why E. leuraensis is endangered. Our 13 populations exhibited similar growth rates and population age structures despite substantial variation in elevation, geographic location and swamp size. However, larger populations (based on a genetic estimate of effective population size) contained older lizards, and thus a wider variance in ages. Conclusion Our study suggests that low adult survival rates, as well as specialisation on a rare and fragmented habitat type (montane swamps) contribute to the endangered status of the Blue Mountains Water Skink. PMID:23402634

Population and development problems: a critical assessment of conventional wisdom. The case of Zimbabwe.

PubMed

Sibanda, A E

1988-01-01

Conventional wisdom, as reflected in reports by the World Bank and the Whitsun Foundation, maintains that control of population growth is the key strategy for stimulating socioeconomic development and ending widespread poverty. The Witsun Foundation has criticized the Government of Zimbabwe for failing to include specific policies for population control in its National Transitional Development Plan. the report further expressed alarm about future availability of land to contain Zimbabwe's growing population. Communal areas are designed for a maximum of 325,000 families yet presently contain 700-800,000 families. This Malthusian, deterministic emphasis on population growth as the source of social ills ignores the broader, complex set of socioeconomic, historical, and political factors that determine material life. Any analysis of population that fails to consider the class structure of society, the type of division of labor, and forms of property and production can produce only meaningless abstractions. For example, consideration of crowding in communal areas must include consideration of inequitable patterns of land ownership in sub-Saharan Africa. Unemployment must be viewed within the context of a capitalist economic structure that relies on an industrial reserve army of labor to ensure acceptance of low wages and labor-intensive conditions. While it is accepted that population growth is creating specific and real problems in Zimbabwe and other African countries, these problems could be ameliorated by land reform and restructuring of the export-oriented colonial economies. Similarly, birth control should not be promoted as the solution to social problems, yet family planning services should be available to raise the status of women. Literacy, agrarian reform, agricultural modernization, and industrialization campaigns free from the dominance of Western capitalism represent the true solutions to Zimbabwe's problems.

Phase Transition for the Maki-Thompson Rumour Model on a Small-World Network

NASA Astrophysics Data System (ADS)

Agliari, Elena; Pachon, Angelica; Rodriguez, Pablo M.; Tavani, Flavia

2017-11-01

We consider the Maki-Thompson model for the stochastic propagation of a rumour within a population. In this model the population is made up of "spreaders", "ignorants" and "stiflers"; any spreader attempts to pass the rumour to the other individuals via pair-wise interactions and in case the other individual is an ignorant, it becomes a spreader, while in the other two cases the initiating spreader turns into a stifler. In a finite population the process will eventually reach an equilibrium situation where individuals are either stiflers or ignorants. We extend the original hypothesis of homogenously mixed population by allowing for a small-world network embedding the model, in such a way that interactions occur only between nearest-neighbours. This structure is realized starting from a k-regular ring and by inserting, in the average, c additional links in such a way that k and c are tuneable parameters for the population architecture. We prove that this system exhibits a transition between regimes of localization (where the final number of stiflers is at most logarithmic in the population size) and propagation (where the final number of stiflers grows algebraically with the population size) at a finite value of the network parameter c. A quantitative estimate for the critical value of c is obtained via extensive numerical simulations.

Potential population-level effects of increased haulout-related mortality of Pacific walrus calves

USGS Publications Warehouse

Udevitz, Mark S.; Taylor, Rebecca L.; Garlich-Miller, Joel L.; Quakenbush, Lori T.; Snyder, Jonathan A.

2013-01-01

Availability of summer sea ice has been decreasing in the Chukchi Sea during recent decades, and increasing numbers of Pacific walruses have begun using coastal haulouts in late summer during years when sea ice retreats beyond the continental shelf. Calves and yearlings are particularly susceptible to being crushed during disturbance events that cause the herd to panic and stampede at these large haulouts, but the potential population-level effects of this mortality are unknown. We used recent harvest data, along with previous assumptions about demographic parameters for this population, to estimate female population size and structure in 2009 and project these numbers forward using a range of assumptions about future harvests and haulout-related mortality that might result from increased use of coastal haulouts during late summer. We found that if demographic parameters were held constant, the levels of harvest that occurred during 1990–2008 would have allowed the population to grow during that period. Our projections indicate, however, that an increase in haulout-related mortality affecting only calves has a greater effect on the population than an equivalent increase in harvest-related mortality distributed among all age classes. Therefore, disturbance-related mortality of calves at coastal haulouts may have relatively important population consequences.

Estimation by capture-recapture of recruitment and dispersal over several sites

USGS Publications Warehouse

Lebreton, J.D.; Hines, J.E.; Pradel, R.; Nichols, J.D.; Spendelow, J.A.

2003-01-01

Dispersal in animal populations is intimately linked with accession to reproduction, i.e. recruitment, and population regulation. Dispersal processes are thus a key component of population dynamics to the same extent as reproduction or mortality processes. Despite the growing interest in spatial aspects of population dynamics, the methodology for estimating dispersal, in particular in relation with recruitment, is limited. In many animal populations, in particular vertebrates, the impossibility of following individuals over space and time in an exhaustive way leads to the need to frame the estimation of dispersal in the context of capture-recapture methodology. We present here a class of age-dependent multistate capture-recapture models for the simultaneous estimation of natal dispersal, breeding dispersal, and age-dependent recruitment. These models are suitable for populations in which individuals are marked at birth and then recaptured over several sites. Under simple constraints, they can be used in populations where non-breeders are not observed, as is often the case with colonial waterbirds monitored on their breeding grounds. Biological questions can be addressed by comparing models differing in structure, according to the generalized linear model philosophy broadly used in capture-recapture methodology. We illustrate the potential of this approach by an analysis of recruitment and dispersal in the roseate tern Sterna dougallii.

Bacterial populations and adaptations in the mucus layers on living corals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ducklow, H.W.; Mitchell, R.

1979-07-01

The external mucus layers of the stony coral Porites astreoides and the soft corals Palythoa sp. and Heteroxenia fuscesens are inhabited by communities of marine heterotrophic bacteria. Population levels of bacteria in coral mucus may be regulated by the self-cleaning behavior of the host. Bacterial populations in coral mucus respond to stresses applied to the host coral by growing to higher population levels in the mucus, indicating that these are populations of viable organisms closely attuned to host metabolism. Members of these microbial populations utilize the mucus compounds and may play a role in processing coral mucus for reef detritusmore » feeders. One such species, Vibrio alginolyticus, grows rapidly on Heteroxenia mucus, is attracted to dissolved mucus, and possesses a mechanism to maintain itself on the coral surface.« less

Scanning Electron Microscope Studies of Interactions between Agaricus bisporus (Lang) Sing Hyphae and Bacteria in Casing Soil

PubMed Central

Masaphy, Segula; Levanon, D.; Tchelet, R.; Henis, Y.

1987-01-01

Relationships between the hyphae of Agaricus bisporus (Lang) Sing and bacteria from the mushroom bed casing layer were examined with a scanning electron microscope. Hyphae growing in the casing layer differed morphologically from compost-grown hyphae. Whereas the compost contained thin single hyphae surrounded by calcium oxalate crystals, the casing layer contained mainly wide hyphae or mycelial strands without crystals. The bacterial population in the hyphal environment consisted of several types, some attached to the hyphae with filamentlike structures. This attachment may be important in stimulation of pinhead initiation. Images PMID:16347340

Weather-Related Hazards and Population Change: A Study of Hurricanes and Tropical Storms in the United States, 1980–2012

PubMed Central

FUSSELL, ELIZABETH; CURRAN, SARA R.; DUNBAR, MATTHEW D.; BABB, MICHAEL A.; THOMPSON, LUANNE; MEIJER-IRONS, JACQUELINE

2017-01-01

Environmental determinists predict that people move away from places experiencing frequent weather hazards, yet some of these areas have rapidly growing populations. This analysis examines the relationship between weather events and population change in all U.S. counties that experienced hurricanes and tropical storms between 1980 and 2012. Our database allows for more generalizable conclusions by accounting for heterogeneity in current and past hurricane events and losses and past population trends. We find that hurricanes and tropical storms affect future population growth only in counties with growing, high-density populations, which are only 2 percent of all counties. In those counties, current year hurricane events and related losses suppress future population growth, although cumulative hurricane-related losses actually elevate population growth. Low-density counties and counties with stable or declining populations experience no effect of these weather events. Our analysis provides a methodologically informed explanation for contradictory findings in prior studies. PMID:29326480

Weather-Related Hazards and Population Change: A Study of Hurricanes and Tropical Storms in the United States, 1980-2012.

PubMed

Fussell, Elizabeth; Curran, Sara R; Dunbar, Matthew D; Babb, Michael A; Thompson, Luanne; Meijer-Irons, Jacqueline

2017-01-01

Environmental determinists predict that people move away from places experiencing frequent weather hazards, yet some of these areas have rapidly growing populations. This analysis examines the relationship between weather events and population change in all U.S. counties that experienced hurricanes and tropical storms between 1980 and 2012. Our database allows for more generalizable conclusions by accounting for heterogeneity in current and past hurricane events and losses and past population trends. We find that hurricanes and tropical storms affect future population growth only in counties with growing, high-density populations, which are only 2 percent of all counties. In those counties, current year hurricane events and related losses suppress future population growth, although cumulative hurricane-related losses actually elevate population growth. Low-density counties and counties with stable or declining populations experience no effect of these weather events. Our analysis provides a methodologically informed explanation for contradictory findings in prior studies.

Landscape Context Affects Aphid Parasitism by Lysiphlebus testaceipes (Hymenoptera: Aphidiinae) in Wheat Fields.

PubMed

Elliott, Norman C; Brewer, Michael J; Giles, Kristopher L

2018-04-12

Winter wheat is Oklahoma's most widely grown crop, and is planted during September and October, grows from fall through spring, and is harvested in June. Winter wheat fields are typically interspersed in a mosaic of habitats in other uses, and we hypothesized that the spatial and temporal composition and configuration of landscape elements, which contribute to agroecosystem diversity also influence biological control of common aphid pests. The parasitoid Lysiphlebus testaceipes (Cresson; Hymenoptera: Aphidiinae) is highly effective at reducing aphid populations in wheat in Oklahoma, and though a great deal is known about the biology and ecology of L. testaceipes, there are gaps in knowledge that limit predicting when and where it will be effective at controlling aphid infestations in wheat. Our objective was to determine the influence of landscape structure on parasitism of cereal aphids by L. testaceipes in wheat fields early in the growing season when aphid and parasitoid colonization occurs and later in the growing season when aphid and parasitoid populations are established in wheat fields. Seventy fields were studied during the three growing seasons. Significant correlations between parasitism by L. testaceipes and landscape variables existed for patch density, fractal dimension, Shannon's patch diversity index, percent wheat, percent summer crops, and percent wooded land. Correlations between parasitism and landscape variables were generally greatest at a 3.2 km radius surrounding the wheat field. Correlations between parasitism and landscape variables that would be expected to increase with increasing landscape diversity were usually positive. Subsequent regression models for L. testaceipes parasitism in wheat fields in autumn and spring showed that landscape variables influenced parasitism and indicated that parasitism increased with increasing landscape diversity. Overall, results indicate that L. testaceipes utilizes multiple habitats throughout the year depending on their availability and acceptability, and frequently disperses among habitats. Colonization of wheat fields by L. testaceipes in autumn appears to be enhanced by proximity to fields of summer crops and semi-natural habitats other than grasslands.

Facilitation as Attenuating of Environmental Stress among Structured Microbial Populations.

PubMed

Martins, Suzana Cláudia Silveira; Santaella, Sandra Tédde; Martins, Claudia Miranda; Martins, Rogério Parentoni

2016-01-01

There is currently an intense debate in microbial societies on whether evolution in complex communities is driven by competition or cooperation. Since Darwin, competition for scarce food resources has been considered the main ecological interaction shaping population dynamics and community structure both in vivo and in vitro. However, facilitation may be widespread across several animal and plant species. This could also be true in microbial strains growing under environmental stress. Pure and mixed strains of Serratia marcescens and Candida rugosa were grown in mineral culture media containing phenol. Growth rates were estimated as the angular coefficients computed from linearized growth curves. Fitness index was estimated as the quotient between growth rates computed for lineages grown in isolation and in mixed cultures. The growth rates were significantly higher in associated cultures than in pure cultures and fitness index was greater than 1 for both microbial species showing that the interaction between Serratia marcescens and Candida rugosa yielded more efficient phenol utilization by both lineages. This result corroborates the hypothesis that facilitation between microbial strains can increase their fitness and performance in environmental bioremediation.

Invasive lionfish drive Atlantic coral reef fish declines.

PubMed

Green, Stephanie J; Akins, John L; Maljković, Aleksandra; Côté, Isabelle M

2012-01-01

Indo-Pacific lionfish (Pterois volitans and P. miles) have spread swiftly across the Western Atlantic, producing a marine predator invasion of unparalleled speed and magnitude. There is growing concern that lionfish will affect the structure and function of invaded marine ecosystems, however detrimental impacts on natural communities have yet to be measured. Here we document the response of native fish communities to predation by lionfish populations on nine coral reefs off New Providence Island, Bahamas. We assessed lionfish diet through stomach contents analysis, and quantified changes in fish biomass through visual surveys of lionfish and native fishes at the sites over time. Lionfish abundance increased rapidly between 2004 and 2010, by which time lionfish comprised nearly 40% of the total predator biomass in the system. The increase in lionfish abundance coincided with a 65% decline in the biomass of the lionfish's 42 Atlantic prey fishes in just two years. Without prompt action to control increasing lionfish populations, similar effects across the region may have long-term negative implications for the structure of Atlantic marine communities, as well as the societies and economies that depend on them.

Invasive Lionfish Drive Atlantic Coral Reef Fish Declines

PubMed Central

Green, Stephanie J.; Akins, John L.; Maljković, Aleksandra; Côté, Isabelle M.

2012-01-01

Indo-Pacific lionfish (Pterois volitans and P. miles) have spread swiftly across the Western Atlantic, producing a marine predator invasion of unparalleled speed and magnitude. There is growing concern that lionfish will affect the structure and function of invaded marine ecosystems, however detrimental impacts on natural communities have yet to be measured. Here we document the response of native fish communities to predation by lionfish populations on nine coral reefs off New Providence Island, Bahamas. We assessed lionfish diet through stomach contents analysis, and quantified changes in fish biomass through visual surveys of lionfish and native fishes at the sites over time. Lionfish abundance increased rapidly between 2004 and 2010, by which time lionfish comprised nearly 40% of the total predator biomass in the system. The increase in lionfish abundance coincided with a 65% decline in the biomass of the lionfish's 42 Atlantic prey fishes in just two years. Without prompt action to control increasing lionfish populations, similar effects across the region may have long-term negative implications for the structure of Atlantic marine communities, as well as the societies and economies that depend on them. PMID:22412895

Phylogeography of Japanese horse chestnut (Aesculus turbinata) in the Japanese Archipelago based on chloroplast DNA haplotypes.

PubMed

Sugahara, Kanako; Kaneko, Yuko; Ito, Satoshi; Yamanaka, Keisuke; Sakio, Hitoshi; Hoshizaki, Kazuhiko; Suzuki, Wajiro; Yamanaka, Norikazu; Setoguchi, Hiroaki

2011-01-01

Japanese horse chestnut (Aesculus turbinata: Hippocastanaceae) is one of the typical woody plants that grow in temperate riparian forests in the Japanese Archipelago. To analyze the phylogeography of this plant in the Japanese Archipelago, we determined cpDNA haplotypes for 337 samples from 55 populations covering the entire distribution range. Based on 1,313 bp of two spacers, we determined ten haplotypes that are distinguished from adjacent haplotypes by one or two steps. Most of the populations had a single haplotype, suggesting low diversity. Spatial analysis of molecular variance suggested three obvious phylogeographic structures in western Japan, where Japanese horse chestnut is scattered and isolated in mountainous areas. Conversely, no clear phylogeographic structure was observed from the northern to the southern limit of this species, including eastern Japan, where this plant is more common. Rare and private haplotypes were also found in southwestern Japan, where Japanese horse chestnuts are distributed sparsely. These findings imply that western Japan might have maintained a relatively large habitat for A. turbinata during the Quaternary climatic oscillations, while northerly regions could not.

Facilitation as Attenuating of Environmental Stress among Structured Microbial Populations

PubMed Central

Santaella, Sandra Tédde; Martins, Claudia Miranda; Martins, Rogério Parentoni

2016-01-01

There is currently an intense debate in microbial societies on whether evolution in complex communities is driven by competition or cooperation. Since Darwin, competition for scarce food resources has been considered the main ecological interaction shaping population dynamics and community structure both in vivo and in vitro. However, facilitation may be widespread across several animal and plant species. This could also be true in microbial strains growing under environmental stress. Pure and mixed strains of Serratia marcescens and Candida rugosa were grown in mineral culture media containing phenol. Growth rates were estimated as the angular coefficients computed from linearized growth curves. Fitness index was estimated as the quotient between growth rates computed for lineages grown in isolation and in mixed cultures. The growth rates were significantly higher in associated cultures than in pure cultures and fitness index was greater than 1 for both microbial species showing that the interaction between Serratia marcescens and Candida rugosa yielded more efficient phenol utilization by both lineages. This result corroborates the hypothesis that facilitation between microbial strains can increase their fitness and performance in environmental bioremediation. PMID:26904719

Role of Alternative Food in Controlling Chaotic Dynamics in a Predator-Prey Model with Disease in the Predator

NASA Astrophysics Data System (ADS)

Das, Krishna Pada; Bairagi, Nandadulal; Sen, Prabir

It is generally, but not always, accepted that alternative food plays a stabilizing role in predator-prey interaction. Parasites, on the other hand, have the ability to change both the qualitative and quantitative dynamics of its host population. In recent times, researchers are showing growing interest in formulating models that integrate both the ecological and epidemiological aspects. The present paper deals with the effect of alternative food on a predator-prey system with disease in the predator population. We show that the system, in the absence of alternative food, exhibits different dynamics viz. stable coexistence, limit cycle oscillations, period-doubling bifurcation and chaos when infection rate is gradually increased. However, when predator consumes alternative food coupled with its focal prey, the system returns to regular oscillatory state from chaotic state through period-halving bifurcations. Our study shows that alternative food may have larger impact on the community structure and may increase population persistence.

Hypertension, obesity, and coronary artery disease in the survivors of congenital heart disease.

PubMed

Roche, S Lucy; Silversides, Candice K

2013-07-01

Obesity, hypertension, and coronary artery disease are prevalent in the general population and well recognized as contributors to cardiac morbidity and mortality. With surgical and medical advances, there is a growing and aging population with congenital heart disease who are also at risk of developing these comorbidities. In addition, some congenital cardiac lesions predispose patients to conditions such as hypertension or coronary artery disease. The effect of these comorbidities on the structurally abnormal heart is not well understood, but might be very important, especially in those with residual abnormalities. Thus, in addition to surveillance for and treatment of late complications it is important for the congenital cardiologist to consider and aggressively manage acquired comorbidities. In this review we explore the prevalence of hypertension, obesity, and coronary artery disease, discuss congenital lesions that predispose to these conditions and review management strategies for this unique population. Copyright © 2013 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

The Impact of Cuban Economic Reform on Older Persons.

PubMed

Strug, David L

2017-03-01

This paper discusses the economic reforms initiated by Cuban President Raúl Castro in 2008 and its effect on the country's fast-growing, vulnerable population of older persons 60+ years of age. Cubans are living longer and the country has a very low birthrate. These two factors combined have reduced the proportion of the population in the work force. This adversely affects the economy. Population aging is a major reason why the government has introduced structural reforms and reduced social spending, which have weakened the welfare state on which older persons depend. Many older persons have become critical of the reforms over time. Policy makers need to address the impact the reforms are having on older Cubans and consider them as active participants in economic reform. Data for this paper come from qualitative, case study research carried out in Havana between the years 2008-15 and from a review of the literature on aging and economic reforms in Cuba. Two case studies illustrate the impact of the economic reforms on older persons.

The quick and the dead: microbial demography at the yeast thermal limit.

PubMed

Maxwell, Colin S; Magwene, Paul M

2017-03-01

The niche of microorganisms is determined by where their populations can expand. Populations can fail to grow because of high death or low birth rates, but these are challenging to measure in microorganisms. We developed a novel technique that enables single-cell measurement of age-structured birth and death rates in the budding yeast, Saccharomyces cerevisiae, and used this method to study responses to heat stress in a genetically diverse panel of strains. We find that individual cells show significant heterogeneity in their rates of birth and death during heat stress. Genotype-by-environment effects on processes that regulate asymmetric cell division contribute to this heterogeneity. These lead to either premature senescence or early life mortality during heat stress, and we find that a mitochondrial inheritance defect explains the early life mortality phenotype of one of the strains we studied. This study demonstrates how the interplay of physiology, genetic variation and environmental variables influence where microbial populations survive and flourish. © 2016 John Wiley & Sons Ltd.

Trade and health in Samoa: views from the insiders.

PubMed

Fa'alili-Fidow, Jacinta; McCool, Judith; Percival, Teuila

2014-04-04

The purpose of this paper is to portray the views of key stakeholders on the potential impacts of Samoa's free trade negotiations and agreements, on health and wellbeing in Samoa. A series of key informant interviews were undertaken with identified stakeholders during June and July, 2011. Interviews were conducted using a semi-structured interview protocol. They were conducted in-person, in New Zealand and in Samoa. Despite potential health and wellbeing gains arising from trade activities (employment, increase in income, health innovations and empowerment of women), key stakeholders expressed a growing concern about the effect of trade on the population's health, nutrition and the rates of non-communicable diseases. Unease about compromising the national policies due to international regulations was also conveyed. Business and trade representatives however, believed that trade benefits outweighed any health and wellbeing risks to the population of Samoa. Further investigation, using new methodologies are required to determine both the opportunities and threats for trade as a mechanism to improve the health of Samoa's population.

[Study on structure and phase transformation laws of natural FeS2 whisker by Raman spectroscopy].

PubMed

Huang, Fei; Kou, Da-Ming; Yao, Yu-Zeng; Ni, Pei; Ding, Jun-Ying

2009-08-01

FeS2 belongs to sulfide, including pyrite of isometric system and marcasite of orthorhombic system. The FeS2 discovered in Gengzhuang, Shanxi Province, was growing in the form of whisker. The study with scanning electron microscopy and electron probe show that the mineral components of FeS2 vary regularly. The structure of natural nano-micron FeS2 whisker was determined by micro-Raman spectroscopy. The results show that there exist two types of structure in FeS2 whiskers: pyrite and marcasite. Marcasite presents irregular shapes, such as coarse lotus root joints, crude columnar or beaded. Pyrite exists in the shape of straight line and smooth surface. In the early growing stage, Gengzhuang FeS2 whisker was mainly marcasite-type structure; in the middle stage it was coexistent structure of pyrite- and marcasite-type; in the late stage it was mainly pyrite-type. The growing stages of the whisker FeS2 show the phase transformation laws. Moreover, during the growing process marcasite was growing with pyrite coated on. Study on FeS2 whisker structure shows that there are correlations between phase transformation laws of the structure and forms, and between the forming time and the composition characteristics.

Population dynamics of rural Ethiopia.

PubMed

Bariabagar, H

1978-01-01

2 rounds of the national sample surveys, conducted by the central statistical office of Ethiopia during 1964-1967 and 1969-1971, provide the only comprehensive demographic data for the country and are the basis for this discussion of rural Ethiopia's population dynamics. The population of Ethiopia is predominantly rural. Agglomerations of 2000 and over inhabitants constitute about 14% of the population, and this indicates that Ethiopia has a low level of urbanization. In rural Ethiopia, international migration was negligent in the 1970's and the age structure can be assumed to be the results of past trends of fertility and mortality conditions. The reported crude birthrate (38.2), crude death rate (12.3) and infant mortality rate (90) of rural Ethiopia fall short of the averages for African countries. Prospects of population growth of rural Ethiopia would be immense. At the rate of natural increase of between 2.4 and 3.0% per annum, the population would double in 24-29 years. Regarding population issues, the programs of the National Democratic Revolution of Ethiopia faces the following main challenging problems: 1) carrying out national population censuses in order to obtain basic information for socialist planning; 2) minimizing or curtailing the existing high urban growth rates; 3) reducing rapidly growing population; and 5) mobilizing Ethiopian women to participate in the social, economic and political life of the country in order to create favorable conditions for future fertility reduction.

Modeling the consequences of the demise and potential recovery of a keystone-species: wild rabbits and avian scavengers in Mediterranean landscapes

PubMed Central

Cortés-Avizanda, Ainara; Colomer, Maria Àngels; Margalida, Antoni; Ceballos, Olga; Donázar, José Antonio

2015-01-01

Restoration of demised keystone-species populations is an overriding concern in conservation biology. However, since no population is independent of its environment, progress is needed in predicting the efficacy of restoration in unstable ecological contexts. Here, by means of Population Dynamics P-system Models (PDP), we studied long-term changes in the population size of Egyptian vultures (Neophron percnopterus) inhabiting a Natural Park, northern Spain, to changes in the numbers of wild rabbits (Oryctolagus cuniculus), a keystone-species of Mediterranean ecosystems that have suffered >90% population decline after a hemorrhagic disease outbreak. Low availability of rabbit carcasses leads Egyptian vultures to extend their foraging activities to unprotected areas with higher non-natural mortality whereas growing numbers of griffon vultures (Gyps fulvus), a dominant competitor, progressively monopolize trophic resources resulting in a focal population decrease. Modeling shows that, even if keystone-species populations recover in core protected areas, the return to the original studied population size may be unfeasible, due to both the high non-natural mortality rates in humanized areas and long-term changes in the scavenger guild structure. Policy decisions aimed to restore keystone-species should rely on holistic approaches integrating the effects of spatial heterogeneity on both producer and consumer populations as well as within-guild processes. PMID:26593338

Counterurbanisation and rural depopulation revisited: landowners, planners and the rural development process.

PubMed

Spencer, D

1997-01-01

"This paper reopens the debate between Weekley (1988) and Rowsell (1989) over why pockets of depopulation have persisted within parts of rural Britain which have experienced net growth through counterurbanisation. It argues that Weekley has not fully appreciated the context for local population losses, namely the emergence of a new structural relationship between people, households, and dwellings, and the growing tension between production and consumption interests in rural locales. Moreover, the paper disputes claims that depopulation is triggered by the actions of either the landowner or the planner. Drawing on case study material informed by critical realism, it argues that planners and landowners have been drawn into an asymmetrical power relationship. This has tended to buttress landed interests and, in so doing, reproduce mechanisms which protect the less populous communities from growth and change." excerpt

Population Genetic Structure and Phylogeography of Camellia flavida (Theaceae) Based on Chloroplast and Nuclear DNA Sequences

PubMed Central

Wei, Su-Juan; Lu, Yong-Bin; Ye, Quan-Qing; Tang, Shao-Qing

2017-01-01

Camellia flavida is an endangered species of yellow camellia growing in limestone mountains in southwest China. The current classification of C. flavida into two varieties, var. flavida and var. patens, is controversial. We conducted a genetic analysis of C. flavida to determine its taxonomic structure. A total of 188 individual plants from 20 populations across the entire distribution range in southwest China were analyzed using two DNA fragments: a chloroplast DNA fragment from the small single copy region and a single-copy nuclear gene called phenylalanine ammonia-lyase (PAL). Sequences from both chloroplast and nuclear DNA were highly diverse; with high levels of genetic differentiation and restricted gene flow. This result can be attributed to the high habitat heterogeneity in limestone karst, which isolates C. flavida populations from each other. Our nuclear DNA results demonstrate that there are three differentiated groups within C. flavida: var. flavida 1, var. flavida 2, and var. patens. These genetic groupings are consistent with the morphological characteristics of the plants. We suggest that the samples included in this study constitute three taxa and the var. flavida 2 group is the genuine C. flavida. The three groups should be recognized as three management units for conservation concerns. PMID:28579991

A Structured Approach Using the Systematic Review Data Repository (SRDR): Building the Evidence for Oral Health Interventions in the Population With Intellectual and Developmental Disability.

PubMed

Bonardi, Alexandra; Clifford, Christine J; Hadar, Nira

2016-08-19

This review describes the methods used for a systematic review of oral health intervention literature in a target population (people with intellectual and developmental disability (I/DD)), which spans a broad range of interventions and study types, conducted with specialized software. The aim of this article is to demonstrate the review strategy, using the free, online systematic review data repository (SRDR) tool, for oral health interventions aimed at reducing disparities between people with I/DD and the general population. Researchers used online title/abstract review (Abstrackr) and data extraction (SRDR) tools to structure the literature review and data extraction. A practicing clinician and an expert methodologist completed the quality review for each study. The data extraction team reported on the experience of using and customizing the SRDR. Using the SRDR, the team developed four extraction templates for eight key questions and completed extraction on 125 articles. This report discusses the advantages and disadvantages of using an electronic tool, such as the SRDR, in completing a systematic review in an area of growing research. This review provides valuable insight for researchers who are considering the use of the SRDR. © The Author(s) 2016.

The Quest to Extend Health Services to Vulnerable Substance Users in Rio de Janeiro, Brazil in the Context of an Unfolding Economic Crisis.

PubMed

Krawczyk, Noa; Kerrigan, Deanna; Bastos, Francisco Inácio

2017-07-01

Calls to address crack-cocaine use in Brazil among homeless and street-frequenting populations who are in urgent need of health services have questioned the capacity of the Brazilian Unified Health System to attend to the nation's most marginalized citizens. In recent years, Brazil has launched several actions to escalate care for substance users, yet many obstacles hindering accessibility and effectiveness of services remain. Paradoxically, these actions have been implemented in the context of a growing economic crisis, and expanding services for a population of poor and stigmatized substance users while cutting other government programs tends to elicit harsh criticism from citizens. In consequence of such prospects, this commentary aims to discuss barriers marginalized substance users face in accessing health services that are at risk of worsening with government cutbacks. Using Rio de Janeiro as an example, we explore two primary issues: the resource-strained, under-staffed and decentralized nature of the Brazilian Unified Health System and the pervading stigma that bars vulnerable citizens from official structures and services. Abandoning initiated government efforts to increase access to health services would risk maintaining vulnerable citizens at the margins of public structures, inhibiting the opportunity to offer this population humane and urgently needed treatment and care.

The Quest to Extend Health Services to Vulnerable Substance Users in Rio de Janeiro, Brazil in the Context of an Unfolding Economic Crisis

PubMed Central

Krawczyk, Noa; Kerrigan, Deanna; Bastos, Francisco Inácio

2018-01-01

Calls to address crack-cocaine use in Brazil among homeless and street-frequenting populations who are in urgent need of health services have questioned the capacity of the Brazilian Unified Health System to attend to the nation’s most marginalized citizens. In recent years, Brazil has launched several actions to escalate care for substance users, yet many obstacles hindering accessibility and effectiveness of services remain. Paradoxically, these actions have been implemented in the context of a growing economic crisis, and expanding services for a population of poor and stigmatized substance users while cutting other government programs tends to elicit harsh criticism from citizens. In consequence of such prospects, this commentary aims to discuss barriers marginalized substance users face in accessing health services that are at risk of worsening with government cutbacks. Using Rio de Janeiro as an example, we explore two primary issues: the resource-strained, under-staffed and decentralized nature of the Brazilian Unified Health System and the pervading stigma that bars vulnerable citizens from official structures and services. Abandoning initiated government efforts to increase access to health services would risk maintaining vulnerable citizens at the margins of public structures, inhibiting the opportunity to offer this population humane and urgently needed treatment and care. PMID:27856941

Marker-trait association analysis of frost tolerance of 672 worldwide pea (Pisum sativum L.) collections.

PubMed

Liu, Rong; Fang, Li; Yang, Tao; Zhang, Xiaoyan; Hu, Jinguo; Zhang, Hongyan; Han, Wenliang; Hua, Zeke; Hao, Junjie; Zong, Xuxiao

2017-07-19

Frost stress is one of the major abiotic stresses causing seedling death and yield reduction in winter pea. To improve the frost tolerance of pea, field evaluation of frost tolerance was conducted on 672 diverse pea accessions at three locations in Northern China in three growing seasons from 2013 to 2016 and marker-trait association analysis of frost tolerance were performed with 267 informative SSR markers in this study. Sixteen accessions were identified as the most winter-hardy for their ability to survive in all nine field experiments with a mean survival rate of 0.57, ranging from 0.41 to 0.75. Population structure analysis revealed a structured population of two sub-populations plus some admixtures in the 672 accessions. Association analysis detected seven markers that repeatedly had associations with frost tolerance in at least two different environments with two different statistical models. One of the markers is the functional marker EST1109 on LG VI which was predicted to co-localize with a gene involved in the metabolism of glycoproteins in response to chilling stress and may provide a novel mechanism of frost tolerance in pea. These winter-hardy germplasms and frost tolerance associated markers will play a vital role in marker-assisted breeding for winter-hardy pea cultivar.

The Undereducation and Overcriminalization of U.S. Latinas/os: A Post-Los Angeles Riots LatCrit Analysis

ERIC Educational Resources Information Center

Gonzalez, Juan Carlos; Portillos, Edwardo L.

2007-01-01

At 40.4 million strong (14% of the U.S. population; U.S. Bureau of the Census 2005), Latinas/os are the largest and fastest growing U.S. ethnic minority group. In the last 15 years, since the Los Angeles riots of 1992, Anglo perceptions that the Latina/o population is too large, growing too fast, and too illegal have both continued and perpetuated…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, William, F.; Kilgo, John, C.; Guynn, David, C.

This report assesses impacts to wild turkey populations from hunting and prescribed fire. The objectives of the study were as follows: (1) To compare survival rates and causes of mortality of wild turkey gobblers between hunted and unhunted populations; (2) To determine the effects of dormant versus growing season prescribed burns on nesting success, survival and habitat use of wild turkey hens; (3) To determine the effects of dormant versus growing season prescribed burns on the availability of wild turkey plant foods.

On the structure-bounded growth processes in plant populations.

PubMed

Kilian, H G; Kazda, M; Király, F; Kaufmann, D; Kemkemer, R; Bartkowiak, D

2010-07-01

If growing cells in plants are considered to be composed of increments (ICs) an extended version of the law of mass action can be formulated. It evidences that growth of plants runs optimal if the reaction-entropy term (entropy times the absolute temperature) matches the contact energy of ICs. Since these energies are small, thermal molecular movements facilitate via relaxation the removal of structure disturbances. Stem diameter distributions exhibit extra fluctuations likely to be caused by permanent constraints. Since the signal-response system enables in principle perfect optimization only within finite-sized cell ensembles, plants comprising relatively large cell numbers form a network of size-limited subsystems. The maximal number of these constituents depends both on genetic and environmental factors. Accounting for logistical structure-dynamics interrelations, equations can be formulated to describe the bimodal growth curves of very different plants. The reproduction of the S-bended growth curves verifies that the relaxation modes with a broad structure-controlled distribution freeze successively until finally growth is fully blocked thus bringing about "continuous solidification".

Age structured dynamical model for an endangered lizard Eulamprus leuraensis

NASA Astrophysics Data System (ADS)

Supriatna, A. K.; Rachmadani, Q.; Ilahi, F.; Anggriani, N.; Nuraini, N.

2014-02-01

The Blue Mountains Water Skink, Eulamprus leuraensis, is listed as an endangered species under the IUCN Red List. This lizard species has a typical characteristic of growth with a low fecundity. It is known that the offspring quality may decline with maternal age of the parents despite they can grow rapidly from neonatal size to adult size within two to three years. It is also believed that low adult survival rates and specialization on rare and fragmented type of habitat are the main cause leading to the endangered status of the lizard. A mathematical model with age structure for Eulamprus leuraensis, taking into account the variation of survival rate in each structure and the declining of offspring quality with respect to maternal age is considered here. Stable coexistence of non-trivial equilibriumis shown. It is also shown that an endangered status is due to combination oflow reproductive output and low rates of adult survival. Further, understanding the age structure within populations can facilitate efective management of the endangered species.

Africa: rapid population increase retards development.

PubMed

1993-10-01

The Organization of African Unity (OAU), the African Development Bank (ADB) and the UN Economic Commission for Africa (ECA) have criticized African governments for not taking the problem of unchecked population growth seriously enough. "Until recently most African governments did not view rapid population growth as a matter for concern," said the OAU assistant secretary-general for political affairs, Machivenyika Mapuranga, at a seminar on 'population and development'. The OAU estimates that an annual average population increase of 3.1% far outstrips Africa's economic growth, which in 1992 was less than 1%. Mapuranga acknowledged that cutting the population increase is an uphill struggle, especially among rural communities. African agriculture is largely labor intensive, sustained by smallholders, which encourages farmers to have more children. Like other wage earners, African farmers look to support from their family when they grow old and, for that reason, the number of children also counts. But with agricultural production growing at an average annual rate of 2.5%, self-sufficiency in food remains an elusive goal. Cities in sub-Saharan Africa are growing much faster than the overall rate of population increase of 3.1% per year. Between 1980 and 1988 the region's urban population increased at the rate of 6.9% a year. Urban areas now account for nearly 30% of the sub-Saharan Africa population, currently put at 680 million. By 2025, approximately 700 million people are expected to live in urban areas. Despite migration to towns, the rural population is expected to rise more than 68%, reaching over 590 million. full text

Differential Response to Soil Salinity in Endangered Key Tree Cactus: Implications for Survival in a Changing Climate

PubMed Central

Goodman, Joie; Maschinski, Joyce; Hughes, Phillip; McAuliffe, Joe; Roncal, Julissa; Powell, Devon; Sternberg, Leonel O'reilly

2012-01-01

Understanding reasons for biodiversity loss is essential for developing conservation and management strategies and is becoming increasingly urgent with climate change. Growing at elevations <1.4 m in the Florida Keys, USA, the endangered Key tree cactus (Pilosocereus robinii) experienced 84 percent loss of total stems from 1994 to 2007. The most severe losses of 99 and 88 percent stems occurred in the largest populations in the Lower Keys, where nine storms with high wind velocities and storm surges, occurred during this period. In contrast, three populations had substantial stem proliferation. To evaluate possible mortality factors related to changes in climate or forest structure, we examined habitat variables: soil salinity, elevation, canopy cover, and habitat structure near 16 dying or dead and 18 living plants growing in the Lower Keys. Soil salinity and elevation were the preliminary factors that discriminated live and dead plants. Soil salinity was 1.5 times greater, but elevation was 12 cm higher near dead plants than near live plants. However, distribution-wide stem loss was not significantly related to salinity or elevation. Controlled salinity trials indicated that salt tolerance to levels above 40 mM NaCl was related to maternal origin. Salt sensitive plants from the Lower Keys had less stem growth, lower root:shoot ratios, lower potassium: sodium ratios and lower recovery rate, but higher δ 13C than a salt tolerant lineage of unknown origin. Unraveling the genetic structure of salt tolerant and salt sensitive lineages in the Florida Keys will require further genetic tests. Worldwide rare species restricted to fragmented, low-elevation island habitats, with little or no connection to higher ground will face challenges from climate change-related factors. These great conservation challenges will require traditional conservation actions and possibly managed relocation that must be informed by studies such as these. PMID:22403670

Differential response to soil salinity in endangered key tree cactus: implications for survival in a changing climate.

PubMed

Goodman, Joie; Maschinski, Joyce; Hughes, Phillip; McAuliffe, Joe; Roncal, Julissa; Powell, Devon; Sternberg, Leonel O'reilly

2012-01-01

Understanding reasons for biodiversity loss is essential for developing conservation and management strategies and is becoming increasingly urgent with climate change. Growing at elevations <1.4 m in the Florida Keys, USA, the endangered Key tree cactus (Pilosocereus robinii) experienced 84 percent loss of total stems from 1994 to 2007. The most severe losses of 99 and 88 percent stems occurred in the largest populations in the Lower Keys, where nine storms with high wind velocities and storm surges, occurred during this period. In contrast, three populations had substantial stem proliferation. To evaluate possible mortality factors related to changes in climate or forest structure, we examined habitat variables: soil salinity, elevation, canopy cover, and habitat structure near 16 dying or dead and 18 living plants growing in the Lower Keys. Soil salinity and elevation were the preliminary factors that discriminated live and dead plants. Soil salinity was 1.5 times greater, but elevation was 12 cm higher near dead plants than near live plants. However, distribution-wide stem loss was not significantly related to salinity or elevation. Controlled salinity trials indicated that salt tolerance to levels above 40 mM NaCl was related to maternal origin. Salt sensitive plants from the Lower Keys had less stem growth, lower root:shoot ratios, lower potassium: sodium ratios and lower recovery rate, but higher δ (13)C than a salt tolerant lineage of unknown origin. Unraveling the genetic structure of salt tolerant and salt sensitive lineages in the Florida Keys will require further genetic tests. Worldwide rare species restricted to fragmented, low-elevation island habitats, with little or no connection to higher ground will face challenges from climate change-related factors. These great conservation challenges will require traditional conservation actions and possibly managed relocation that must be informed by studies such as these.

50 CFR 17.84 - Special rules-vertebrates.

Code of Federal Regulations, 2011 CFR

2011-10-01

... too steep to support populations of woundfin. (7) The reintroduced populations will be checked... population grows from the point of being established toward the maximum number that its habitat can support... decision to terminate the translocated population. A joint State-Service consultation will determine when...

Optimal savings and the value of population.

PubMed

Arrow, Kenneth J; Bensoussan, Alain; Feng, Qi; Sethi, Suresh P

2007-11-20

We study a model of economic growth in which an exogenously changing population enters in the objective function under total utilitarianism and into the state dynamics as the labor input to the production function. We consider an arbitrary population growth until it reaches a critical level (resp. saturation level) at which point it starts growing exponentially (resp. it stops growing altogether). This requires population as well as capital as state variables. By letting the population variable serve as the surrogate of time, we are still able to depict the optimal path and its convergence to the long-run equilibrium on a two-dimensional phase diagram. The phase diagram consists of a transient curve that reaches the classical curve associated with a positive exponential growth at the time the population reaches the critical level. In the case of an asymptotic population saturation, we expect the transient curve to approach the equilibrium as the population approaches its saturation level. Finally, we characterize the approaches to the classical curve and to the equilibrium.

Optimal savings and the value of population

PubMed Central

Arrow, Kenneth J.; Bensoussan, Alain; Feng, Qi; Sethi, Suresh P.

2007-01-01

We study a model of economic growth in which an exogenously changing population enters in the objective function under total utilitarianism and into the state dynamics as the labor input to the production function. We consider an arbitrary population growth until it reaches a critical level (resp. saturation level) at which point it starts growing exponentially (resp. it stops growing altogether). This requires population as well as capital as state variables. By letting the population variable serve as the surrogate of time, we are still able to depict the optimal path and its convergence to the long-run equilibrium on a two-dimensional phase diagram. The phase diagram consists of a transient curve that reaches the classical curve associated with a positive exponential growth at the time the population reaches the critical level. In the case of an asymptotic population saturation, we expect the transient curve to approach the equilibrium as the population approaches its saturation level. Finally, we characterize the approaches to the classical curve and to the equilibrium. PMID:17984059

Evolution of a Fluctuating Population in a Randomly Switching Environment.

PubMed

Wienand, Karl; Frey, Erwin; Mobilia, Mauro

2017-10-13

Environment plays a fundamental role in the competition for resources, and hence in the evolution of populations. Here, we study a well-mixed, finite population consisting of two strains competing for the limited resources provided by an environment that randomly switches between states of abundance and scarcity. Assuming that one strain grows slightly faster than the other, we consider two scenarios-one of pure resource competition, and one in which one strain provides a public good-and investigate how environmental randomness (external noise) coupled to demographic (internal) noise determines the population's fixation properties and size distribution. By analytical means and simulations, we show that these coupled sources of noise can significantly enhance the fixation probability of the slower-growing species. We also show that the population size distribution can be unimodal, bimodal, or multimodal and undergoes noise-induced transitions between these regimes when the rate of switching matches the population's growth rate.

Evolution of a Fluctuating Population in a Randomly Switching Environment

NASA Astrophysics Data System (ADS)

Wienand, Karl; Frey, Erwin; Mobilia, Mauro

2017-10-01

Environment plays a fundamental role in the competition for resources, and hence in the evolution of populations. Here, we study a well-mixed, finite population consisting of two strains competing for the limited resources provided by an environment that randomly switches between states of abundance and scarcity. Assuming that one strain grows slightly faster than the other, we consider two scenarios—one of pure resource competition, and one in which one strain provides a public good—and investigate how environmental randomness (external noise) coupled to demographic (internal) noise determines the population's fixation properties and size distribution. By analytical means and simulations, we show that these coupled sources of noise can significantly enhance the fixation probability of the slower-growing species. We also show that the population size distribution can be unimodal, bimodal, or multimodal and undergoes noise-induced transitions between these regimes when the rate of switching matches the population's growth rate.

qRT-PCR quantification of the biological control agent Trichoderma harzianum in peat and compost-based growing media.

PubMed

Beaulieu, Robert; López-Mondéjar, Rubén; Tittarelli, Fabio; Ros, Margarita; Pascual, José Antonio

2011-02-01

To ensure proper use of Trichoderma harzianum in agriculture, accurate data must be obtained in population monitoring. The effectiveness of qRT-PCR to quantify T. harzianum in different growing media was compared to the commonly used techniques of colony counting and qPCR. Results showed that plate counting and qPCR offered similar T. harzianum quantification patterns of an initial rapid increase in fungal population that decreased over time. However, data from qRT-PCR showed a population curve of active T. harzianum with a delayed onset of initial growth which then increased throughout the experiment. Results demonstrated that T. harzianum can successfully grow in these media and that qRT-PCR can offer a more distinct representation of active T. harzianum populations. Additionally, compost amended with T. harzianum exhibited a lower Fusarium oxysporum infection rate (67%) and lower percentage of fresh weight loss (11%) in comparison to amended peat (90% infection rate, 23% fresh weight loss). Copyright © 2010 Elsevier Ltd. All rights reserved.

Social Effects of Prospective Population Changes in the United States.

ERIC Educational Resources Information Center

Kirk, Dudley

Unlike many population forecasts, the thesis of this paper is that present and prospective effects of population growth in the United States have been exaggerated in comparison with other aspects of population change. The effects of national population growth have been confused with those of growing affluence, changing technology, and…

Inference of cell-cell interactions from population density characteristics and cell trajectories on static and growing domains.

PubMed

Ross, Robert J H; Yates, C A; Baker, R E

2015-06-01

A key feature of cell migration is how cell movement is affected by cell-cell interactions. Furthermore, many cell migratory processes such as neural crest stem cell migration [Thomas and Erickson, 2008; McLennan et al., 2012] occur on growing domains or in the presence of a chemoattractant. Therefore, it is important to study interactions between migrating cells in the context of domain growth and directed motility. Here we compare discrete and continuum models describing the spatial and temporal evolution of a cell population for different types of cell-cell interactions on static and growing domains. We suggest that cell-cell interactions can be inferred from population density characteristics in the presence of motility bias, and these population density characteristics for different cell-cell interactions are conserved on both static and growing domains. We also study the expected displacement of a tagged cell, and show that different types of cell-cell interactions can give rise to cell trajectories with different characteristics. These characteristics are conserved in the presence of domain growth, however, they are diminished in the presence of motility bias. Our results are relevant for researchers who study the existence and role of cell-cell interactions in biological systems, so far as we suggest that different types of cell-cell interactions could be identified from cell density and trajectory data. Copyright © 2015 Elsevier Inc. All rights reserved.

ALMA observations of protoplanetary disks

NASA Astrophysics Data System (ADS)

Hogerheijde, Michiel

2015-08-01

The Universe is filled with planetary systems, as recent detections of exo-planets have shown. Such systems grow out of disks of gas and dust that surround newly formed stars. The ground work for our understanding of the structure, composition, and evolution of such disks has been laid with infrared telescopes in the 1980's, 1990's, and 2000's, as well as with millimeter interferometers operating in the United States, France, and Japan. With the construction of the Atacama Large Millimeter / submillimeter Array, a new era of studying planet-forming disks has started. The unprecedented leap in sensitivity and angular resolution that ALMA offers, has truely revolutionized our understanding of disks. No longer featureless objects consisting of gas and smalll dust, they are now seen to harbor a rich structure and chemistry. The ongoing planet-formation process sculpts many disks into systems of rings and arcs; grains grown to millimeter-sizes collect in high-pressure areas where they could grow out to asteroids or comets or further generations of planets. This wealth of new information directly addresses bottlenecks in our theoretical understanding of planet formation, such as the question how grains can grow past the 'meter-sized' barrier or overcome the 'drift barrier', and how gas and ice evolve together and ultimately determine the elemental compositions of both giant and terrestrial planets. I will review the recent ALMA results on protoplanetary disks, presenting results on individual objects and from the first populations studies. I will conclude with a forward look, on what we might expect from ALMA in this area for the years and decades to come.

Global MLST of Salmonella Typhi Revisited in Post-genomic Era: Genetic Conservation, Population Structure, and Comparative Genomics of Rare Sequence Types.

PubMed

Yap, Kien-Pong; Ho, Wing S; Gan, Han M; Chai, Lay C; Thong, Kwai L

2016-01-01

Typhoid fever, caused by Salmonella enterica serovar Typhi, remains an important public health burden in Southeast Asia and other endemic countries. Various genotyping methods have been applied to study the genetic variations of this human-restricted pathogen. Multilocus sequence typing (MLST) is one of the widely accepted methods, and recently, there is a growing interest in the re-application of MLST in the post-genomic era. In this study, we provide the global MLST distribution of S. Typhi utilizing both publicly available 1,826 S. Typhi genome sequences in addition to performing conventional MLST on S. Typhi strains isolated from various endemic regions spanning over a century. Our global MLST analysis confirms the predominance of two sequence types (ST1 and ST2) co-existing in the endemic regions. Interestingly, S. Typhi strains with ST8 are currently confined within the African continent. Comparative genomic analyses of ST8 and other rare STs with genomes of ST1/ST2 revealed unique mutations in important virulence genes such as flhB, sipC, and tviD that may explain the variations that differentiate between seemingly successful (widespread) and unsuccessful (poor dissemination) S. Typhi populations. Large scale whole-genome phylogeny demonstrated evidence of phylogeographical structuring and showed that ST8 may have diverged from the earlier ancestral population of ST1 and ST2, which later lost some of its fitness advantages, leading to poor worldwide dissemination. In response to the unprecedented increase in genomic data, this study demonstrates and highlights the utility of large-scale genome-based MLST as a quick and effective approach to narrow the scope of in-depth comparative genomic analysis and consequently provide new insights into the fine scale of pathogen evolution and population structure.

Population structure and diversity of citrus tristeza virus (CTV) isolates in Hunan province, China.

PubMed

Xiao, Cui; Yao, Run-Xian; Li, Fang; Dai, Su-Ming; Licciardello, Grazia; Catara, Antonino; Gentile, Alessandra; Deng, Zi-Niu

2017-02-01

Stem-pitting (SP) is the main type of citrus tristeza virus (CTV) that causes severe damage to citrus trees, especially those of sweet orange, in Hunan province, China. Understanding the local CTV population structure should provide clues for effective mild strain cross-protection (MSCP) of the SP strain of CTV. In this study, markers for the p23 gene, multiple molecular markers (MMMs), and sequence analysis of the three silencing suppressor genes (p20, p23 and p25) were employed to analyze the genetic diversity and genotype composition of the CTV population based on 51 CTV-positive samples collected from 14 citrus orchards scattered around six major citrus-growing areas of Hunan. The results indicated that the CTV population structure was extremely complex and that infection was highly mixed. In total, p23 gene markers resulted in six profiles, and MMMs demonstrated 25 profiles. The severe VT and T3 types appeared to be predominantly associated with SP, while the mild T30 and RB types were related to asymptomatic samples. Based on phylogenetic analysis of the amino acid sequences of p20, p23 and p25, 19 representative CTV samples were classified into seven recently established CTV groups and a potentially novel one. A high level of genetic diversity, as well as potential recombination, was revealed among different CTV isolates. Five pure SP severe and two pure mild strains were identified by genotype composition analysis. Taken together, the results update the genetic diversity of CTV in Hunan with the detection of one possible novel strain, and this information might be applicable for the selection of appropriate mild CTV strains for controlling citrus SP disease through cross-protection.

Population: A Lively Introduction.

ERIC Educational Resources Information Center

McFalls, Joseph A., Jr.

1991-01-01

The study of demography must begin with an understanding of the three sources of population changes: fertility, mortality, and migration. This paper leads prospective demographers--or anyone interested in population--through the dynamics of these three variables, introducing them to the forces that cause populations to grow or decline, and that…

Water, climate change and society in Bangladesh

NASA Astrophysics Data System (ADS)

Thiele-Eich, Insa; Aßheuer, Tibor; Simmer, Clemens

2017-04-01

Due to its location in the extensive Ganges-Brahmaputra-Meghna river delta, Bangladesh faces multiple natural hazards, in particular flooding, droughts and sea-level rise. In addition to climate change, transboundary water sharing issues resulting from dam structures such as Farakka Barrage complicate a prognosis on how the rapidly growing population will be affected in the 21st century. This is particularly important as our previous research suggests that the Greater Dhaka population already experiences a significant increase in mortality during droughts (Thiele-Eich et al., 2015). We attempt to explore the complex interactions between the hydrological system under climate change and anthropogenic impacts due to dams as well as a growing population. Our approach consists of a quantitative assessment of climate change using over fourty years of meteorological data (Bangladesh Meteorological Department) and hydrological data (Bangladesh Water Development Board), and CCSM4 climate model output (NCAR, 1950-2100). In addition to an extensive literature review, we also conducted qualitative interviews with slum dwellers in the megacity Dhaka, the capital of Bangladesh. Results show that significant changes in flood characteristics are expected for the later part of the 21st century, although they are difficult to quantify down to exact numbers due to large uncertainties. These changes take place over longer stretches of time and thus enable the population of Bangladesh to adapt slowly. Resources such as social capital, which is one of the main tools for slum dwellers to be able to cope with flooding can be altered over time, and as such the system can be considered overall stable and resilient. The presented results will also focus on how the riparian and coastal population is impacted by the interplay of natural changes such as sea-level rise and anthropogenic changes such as Farakka Barrage and the associated reduction in dry season flow. Thiele-Eich, I.; Burkart, K.; Simmer, C. Trends in Water Level and Flooding in Dhaka, Bangladesh and Their Impact on Mortality. Int. J. Environ. Res. Public Health 2015, 12, 1196-1215.

Aging and health among migrants in a European perspective.

PubMed

Kristiansen, Maria; Razum, Oliver; Tezcan-Güntekin, Hürrem; Krasnik, Allan

Population aging and the associated changes in demographic structures and healthcare needs is a key challenge across Europe. Healthy aging strategies focus on ensuring the ability to maintain health, quality of life and independent living at old age. Concurrent to the process of population aging, the demographics of Europe are affected by increased migration resulting in substantial ethnic diversity. In this paper, we narratively review the health profile of the growing proportion of aging migrants in Europe, outline key factors shaping health among this diverse group and consider ways of addressing their healthcare needs. Although factors shaping aging processes are largely similar across populations, migrant-specific risk factors exist. These include exposure to health risks before and during migration; a more disadvantaged socioeconomic position; language barriers and low health literacy; cultural factors influencing health-seeking behaviours; and psychosocial vulnerability and discrimination affecting health and quality of life. Overall, migrants experience the same morbidity and mortality causes as the native populations, but with different relative importance, severity and age of onset and with substantial differences within and between migrant groups. Little is known regarding health behaviours among aging migrants, although differences in cancer screening behaviours have been identified. Indications of widening health differentials between migrants and native populations with age and informal barriers to quality healthcare for aging migrants are causes of concern. In conclusion, there is a need for attention to migration alongside other determinants of healthy aging. The diversity in individual characteristics, life course processes and contextual factors shaping aging processes among migrants point to the need for a sensitive and comprehensive approach to policies, practices and research within the field of healthy aging. This is important to accommodate for the needs of the growing number of aging migrants in Europe and counter inequities in health and well-being at old age.

Persistence of historical population structure in an endangered species despite near-complete biome conversion in California's San Joaquin Desert

USGS Publications Warehouse

Richmond, Jonathan Q.; Wood, Dustin A.; Westphal, Michael F.; Vandergast, Amy; Leache, Adam D.; Saslaw, Lawrence; Butterfield, H. Scott; Fisher, Robert N.

2017-01-01

Genomic responses to habitat conversion can be rapid, providing wildlife managers with time-limited opportunities to enact recovery efforts that use population connectivity information that reflects predisturbance landscapes. Despite near-complete biome conversion, such opportunities may still exist for the endemic fauna and flora of California's San Joaquin Desert, but comprehensive genetic data sets are lacking for nearly all species in the region. To fill this knowledge gap, we studied the rangewide population structure of the endangered blunt-nosed leopard lizard Gambelia sila, a San Joaquin Desert endemic, using restriction site-associated DNA (RAD), microsatellite and mtDNA data to test whether admixture patterns and estimates of effective migration surfaces (EEMS) can identify land areas with high population connectivity prior to the conversion of native xeric habitats. Clustering and phylogenetic analyses indicate a recent shared history between numerous isolated populations and EEMS reveals latent signals of corridors and barriers to gene flow over areas now replaced by agriculture and urbanization. Conflicting histories between the mtDNA and nuclear genomes are consistent with hybridization with the sister species G. wislizenii, raising important questions about where legal protection should end at the southern range limit of G. sila. Comparative analysis of different data sets also adds to a growing list of advantages in using RAD loci for genetic studies of rare species. We demonstrate how the results of this work can serve as an evolutionary guidance tool for managing endemic, arid-adapted taxa in one of the world's most compromised landscapes.

Adaptation and diversity along an altitudinal gradient in Ethiopian barley (Hordeum vulgare L.) landraces revealed by molecular analysis

PubMed Central

2010-01-01

Background Among the cereal crops, barley is the species with the greatest adaptability to a wide range of environments. To determine the level and structure of genetic diversity in barley (Hordeum vulgare L.) landraces from the central highlands of Ethiopia, we have examined the molecular variation at seven nuclear microsatellite loci. Results A total of 106 landrace populations were sampled in the two growing seasons (Meher and Belg; the long and short rainy seasons, respectively), across three districts (Ankober, Mojanawadera and Tarmaber), and within each district along an altitudinal gradient (from 1,798 to 3,324 m a.s.l). Overall, although significant, the divergence (e.g. FST) is very low between seasons and geographical districts, while it is high between different classes of altitude. Selection for adaptation to different altitudes appears to be the main factor that has determined the observed clinal variation, along with population-size effects. Conclusions Our data show that barley landraces from Ethiopia are constituted by highly variable local populations (farmer's fields) that have large within-population diversity. These landraces are also shown to be locally adapted, with the major driving force that has shaped their population structure being consistent with selection for adaptation along an altitudinal gradient. Overall, our study highlights the potential of such landraces as a source of useful alleles. Furthermore, these landraces also represent an ideal system to study the processes of adaptation and for the identification of genes and genomic regions that have adaptive roles in crop species. PMID:20565982

Population Structure, Diversity and Reproductive Mode of the Grape Phylloxera (Daktulosphaira vitifoliae) across Its Native Range

PubMed Central

Walker, M. Andrew

2017-01-01

Grape Phylloxera, Daktulosphaira vitifoliae, is a gall-forming insect that feeds on the leaves and roots of many Vitis species. The roots of the cultivated V. vinifera cultivars and hybrids are highly susceptible to grape phylloxera feeding damage. The native range of this insect covers most of North America, and it is particularly abundant in the eastern and central United States. Phylloxera was introduced from North America to almost all grape-growing regions across five of the temperate zone continents. It devastated vineyards in each of these regions causing large-scale disruptions to grape growers, wine makers and national economies. In order to understand the population diversity of grape phylloxera in its native range, more than 500 samples from 19 States and 34 samples from the introduced range (northern California, Europe and South America) were genotyped with 32 simple sequence repeat markers. STRUCTURE, a model based clustering method identified five populations within these samples. The five populations were confirmed by a neighbor-joining tree and principal coordinate analysis (PCoA). These populations were distinguished by their Vitis species hosts and their geographic locations. Samples collected from California, Europe and South America traced back to phylloxera sampled in the northeastern United States on V. riparia, with some influence from phylloxera collected along the Atlantic Coast and Central Plains on V. vulpina. Reproductive statistics conclusively confirmed that sexual reproduction is common in the native range and is combined with cyclical parthenogenesis. Native grape phylloxera populations were identified to be under Hardy-Weinberg equilibrium. The identification of admixed samples between many of these populations indicates that shared environments facilitate sexual reproduction between different host associated populations to create new genotypes of phylloxera. This study also found that assortative mating might occur across the sympatric range of the V. vulpina west and V. cinerea populations. PMID:28125736

Responses to alternative rainfall regimes and antipoaching in a migratory system.

PubMed

Holdo, Ricardo M; Galvin, Kathleen A; Knapp, Eli; Polasky, Stephen; Hilborn, Ray; Holt, Robert D

2010-03-01

Migratory ungulates may be particularly vulnerable to the challenges imposed by growing human populations and climate change. These species depend on vast areas to sustain their migratory behavior, and in many cases come into frequent contact with human populations outside protected areas. They may also act as spatial coupling agents allowing feedbacks between ecological systems and local economies, particularly in the agropastoral subsistence economies found in the African savanna biome. We used HUMENTS, a spatially realistic socioecological model of the Greater Serengeti Ecosystem in East Africa, to explore the potential impacts of changing climate and poaching on the migratory wildebeest (Connochaetes taurinus) population, the fire regime, and habitat structure in the ecosystem, as well as changes in the size and economic activities of the human population outside the protected area. Unlike earlier models, the HUMENTS model predicted only moderate declines in the wildebeest population associated with an increasing human population over the next century, with a gradual expansion of agriculture, more poaching, and increases in fire frequency and reduced tree density. Changes in rainfall were predicted to have strong asymmetric effects on the size and economic activity of the human population and on livestock, and more moderate effects on wildlife and other ecological indicators. Conversely, antipoaching had a stronger effect on the ecological portion of the system because of its effect on wildebeest (and therefore on fire and habitat structure), and a weaker effect on the socioeconomic component, except in areas directly adjacent to the protected-area boundary, which were affected by crop-raiding and the availability of wildlife as a source of income. The results highlight the strong direct and indirect effects of rainfall on the various components of socioecological systems in semiarid environments, and the key role of mobile wildlife populations as agents of spatial coupling between the human-dominated and natural portions of ecosystems. They also underscore the fundamental importance of considering the spatial configuration of hunting refuges across the landscape in relation to human populations.

Removal of metal ions from contaminated water using agricultural residues

Treesearch

Roger M. Rowell

2006-01-01

As the world population grows, there is a growing awareness that our environment is getting more polluted. Clean water is becoming a critical issue for many parts of the world for human, animal and agricultural use. Filtration systems to clean our air and water are a growing industry. There are many approaches to removing contaminates from our water supply ranging from...

Population Education: Lessons for a Changing World.

ERIC Educational Resources Information Center

Wasserman, Pamela

1996-01-01

Considers the global effects of a rapidly growing population combined with dwindling natural resources and how these issues might be addressed in the classroom. Includes a population education lesson plan, guiding principles, list of resources, and suggested activities. (MJP)

Urban Space as the Commons - New Modes for Urban Space Management

NASA Astrophysics Data System (ADS)

Ondrejicka, Vladimir; Finka, Maros; Husar, Milan; Jamecny, Lubomir

2017-12-01

The significant growing of urban population, globalization of social-ecological systems, fuzzification of spatial structures, the diversity of actors in spatial development, their power and interest in using the resources including space, especially in high-density urban areas. Spatial development is connected with a high concentration of economic activities and population in urban systems. In many cases very rapid processes of urbanization and suburbanization approach natural spatial/territorial limits, such as carrying capacity of land, transport and infrastructural systems, absorption capacities of recipients and others [1]. Growing shortage of space and problems in their accessibility (physical, functional, etc.) leads to growing tension and conflicts among the actors/users of urban spaces and represent the initial phase of space deprivations processes. There is a parallel with “tragedy of commons” as defined by Hardin [2] and was reinterpreted by many other academics and researchers. Urban space can be clearly interpreted as the commons or commons good for their community of users and relevant actors, so innovative governance modes overlapping defined “tragedy of commons” representing a possible approach for a new concept of urban public spaces management. This paper presents a possible new approach to the management of urban spaces reflecting the current challenges in spatial development based on the theory of commons and innovative governance modes. The new approach is built on innovations in institutional regimes, the algorithm of decision-making and economic expression and interpretation of quality of the space. The theory of the commons as the base source for this approach has been broadly proved in practice and Elinor Ostrom as the author of this theory [3-5] was awarded by Nobel Prize in 2009.

Catholic perspectives on populations issues II.

PubMed

Murphy, F X

1981-02-01

This Bulletin discusses the history and current status of the population problem from a Roman Catholic viewpoint. While upholding human rights and admitting the right of couples to control the size of their families, the Catholic Church continues to prohibit the use of artificial methods of contraception as sinful. This position hinders the Church, with its some 750 million adherents, from taking an effective lead in confronting the growing threat of global overpopulation. Rhythm has been permitted since 1930 but Pope Pius 12 in 1958 forbade contraceptive use of the pill. Despite the liberal spirit engendered by Vatican Council 2 and against the recommendation of a papal birth control commission, Pope Paul 6 in his 1968 Encyclical Humanae vitae reaffirmed the ban on artificial contraception, apparently convinced that this was necessary to combat growing sexual immorality, family breakdown, and materialism. This stance has been upheld by Pope John Paul 2 and the 1980 Synod of Bishops. The decision ignores the pleas of a number of responsible churchmen speaking for their people at the Synod and of a growing majority of Catholic theologians and laity, that Church teaching must be updated to take account of the facts of modern life. Surveys reveal that Catholic married couples increasingly find Church-approved natural family planning methods unsatisfactory and feel obliged to turn to artificial methods to regulate their family size. On the world scale, Pope John Paul 2 and the Vatican, while insisting on human rights and the need for a reordering of unjust economic, social, and political structures, seem to be neglecting the threat of civilizational breakdown that looms with the prospect of too many people in too little space with too few resources.

Climate change accelerates local disease extinction rates in a long-term wild host-pathogen association.

PubMed

Zhan, Jiasui; Ericson, Lars; Burdon, Jeremy J

2018-02-27

Pathogens are a significant component of all plant communities. In recent years, the potential for existing and emerging pathogens of agricultural crops to cause increased yield losses as a consequence of changing climatic patterns has raised considerable concern. In contrast, the response of naturally occurring, endemic pathogens to a warming climate has received little attention. Here, we report on the impact of a signature variable of global climate change - increasing temperature - on the long-term epidemiology of a natural host-pathogen association involving the rust pathogen Triphragmium ulmariae and its host plant Filipendula ulmaria. In a host-pathogen metapopulation involving approximately 230 host populations growing on an archipelago of islands in the Gulf of Bothnia we assessed changes in host population size and pathogen epidemiological measures over a 25-year period. We show how the incidence of disease and its severity declines over that period and most importantly demonstrate a positive association between a long-term trend of increasing extinction rates in individual pathogen populations of the metapopulation and increasing temperature. Our results are highly suggestive that changing climatic patterns, particularly mean monthly growing season (April-November) temperature, are markedly influencing the epidemiology of plant disease in this host-pathogen association. Given the important role plant pathogens have in shaping the structure of communities, changes in the epidemiology of pathogens have potentially far-reaching impacts on ecological and evolutionary processes. For these reasons, it is essential to increase understanding of pathogen epidemiology, its response to warming, and to invoke these responses in forecasts for the future. © 2018 John Wiley & Sons Ltd.

Lake whitefish and Diporeia spp. in the Great lakes: an overview

USGS Publications Warehouse

Nalepa, Thomas F.; Mohr, Lloyd C.; Henderson, Bryan A.; Madenjian, Charles P.; Schneeberger, Philip J.

2005-01-01

Because of growing concern in the Great Lakes over declines in abundance and growth of lake whitefish (Coregonus clupeaformis) and declines in abundance of the benthic amphipod Diporeia spp., a workshop was held to examine past and current trends, to explore trophic links, and to discuss the latest research results and needs. The workshop was divided into sessions on the status of populations in each of the lakes, bioenergetics and trophic dynamics, and exploitation and management. Abundance, growth, and condition of whitefish populations in Lakes Superior and Erie are stable and within the range of historical means, but these variables are declining in Lakes Michigan and Ontario and parts of Lake Huron. The loss of Diporeia spp., a major food item of whitefish, has been a factor in observed declines, particularly in Lake Ontario, but density-dependent factors also likely played a role in Lakes Michigan and Huron. The loss of Diporeia spp. is temporally linked to the introduction and proliferation of dreissenid mussels, but a direct cause for the negative response of Diporeia spp. has not been established. Given changes in whitefish populations, age-structured models need to be re-evaluated. Other whitefish research needs to include a better understanding of what environmental conditions lead to strong year-classes, improved aging techniques, and better information on individual population (stock) structure. Further collaborations between assessment biologists and researchers studying the lower food web would enhance an understanding of links between trophic levels.

Isolation and Characterization of Novel Polymorphic Microsatellite Markers for Cimex hemipterus F. (Hemiptera: Cimicidae).

PubMed

Seri Masran, Siti Nor Ain; Ab Majid, Abdul Hafiz

2018-05-04

Due to the growing public health and tourism awareness, Cimex hemipterus Fabricius (Hemiptera: Cimicidae) has gained a great interest in increasing reported infestation cases in tropical regions of the world, including Malaysia. Since the information on the molecular ecology and population biology of this species are tremendously lacking, the isolation and development of molecular markers can be used to determine its genetic structure. In this study, novel microsatellite primers isolated from enriched genomic libraries of C. hemipterus were developed using 454 Roche shotgun sequencing. Seven validated polymorphic microsatellite primers were consistently amplified and characterized from 70 tropical bed bugs collected from seven locations throughout Malaysia. The number of alleles per locus identified ranged from 6 to 14. Comparison of loci for overall and between population were done with mean observed and expected heterozygosity were determined at 0.320 and 0.814, 0.320 and 0.727, respectively. Polymorphic information criteria (PIC) valued the markers as highly informative as PIC >0.5. Overall population, they are possibly in Hardy-Weinberg equilibrium with loci Ch_09ttn, Ch_01dn, and Ch_13dn showing signs of a null allele. There were no scoring errors caused by stutter peaks, no large allele dropout was detected for all loci and showed no evidence of linkage disequilibrium. In conclusion, all seven molecular microsatellite markers identified can be beneficially used to gain more information on the population genetic structure and breeding patterns of C. hemipterus as well as the relationship of dispersal and infestation.

Specific, non-nutritional association between an ascomycete fungus and Allomerus plant-ants.

PubMed

Ruiz-González, Mario X; Malé, Pierre-Jean G; Leroy, Céline; Dejean, Alain; Gryta, Hervé; Jargeat, Patricia; Quilichini, Angélique; Orivel, Jérôme

2011-06-23

Ant-fungus associations are well known from attine ants, whose nutrition is based on a symbiosis with basidiomycete fungi. Otherwise, only a few non-nutritional ant-fungus associations have been recorded to date. Here we focus on one of these associations involving Allomerus plant-ants that build galleried structures on their myrmecophytic hosts in order to ambush prey. We show that this association is not opportunistic because the ants select from a monophyletic group of closely related fungal haplotypes of an ascomycete species from the order Chaetothyriales that consistently grows on and has been isolated from the galleries. Both the ants' behaviour and an analysis of the genetic population structure of the ants and the fungus argue for host specificity in this interaction. The ants' behaviour reveals a major investment in manipulating, growing and cleaning the fungus. A molecular analysis of the fungus demonstrates the widespread occurrence of one haplotype and many other haplotypes with a lower occurrence, as well as significant variation in the presence of these fungal haplotypes between areas and ant species. Altogether, these results suggest that such an interaction might represent an as-yet undescribed type of specific association between ants and fungus in which the ants cultivate fungal mycelia to strengthen their hunting galleries.

Forecasting the burden of future postmenopausal hip fractures.

PubMed

Omsland, T K; Magnus, J H

2014-10-01

A growing elderly population is expected worldwide, and the rate of hip fractures is decisive for the future fracture burden. Significant declines in hip fracture rates in Norway, the USA, France, Germany, and the UK are required to counteract the impact of the ageing effects. This study aims to evaluate the consequences of the expected growth of the elderly population worldwide on the hip fracture burden using Norway as an example. Furthermore, we wanted to estimate the decline in hip fracture rates required to counteract the anticipated increase in the burden of hip fracture for Norway, the USA, France, Germany, and the UK. The burden of future postmenopausal hip fractures in Norway were estimated given (1) constant age-specific rates, (2) continued decline, and (3) different cohort scenarios. Based on population projection estimates and population age-specific hip fracture rates in women 65 years and older, we calculated the required declines in hip fracture rates needed to counteract the growing elderly populations in Norway, the USA, France, Germany, and the UK. The level of age-specific hip fracture rates had a huge impact on the future hip fracture burden in Norway. Even if the hip fracture rates decline at the same speed, a 22 % increase in the burden of hip fractures can be expected by 2040. An annual decline in hip fracture rates of 1.1-2.2 % until 2040 is required to counteract the effects of the growing elderly population on the future burden of hip fractures in Norway, the USA, France, Germany, and the UK. Hip fracture rates have a great impact on the burden of hip fractures. The rates will have to decline significantly to counteract the impact of a growing elderly population. A change in preventive strategies and further studies are warranted to identify the complex causes associated to hip fractures.

The dimensional structure of psychopathology in 22q11.2 Deletion Syndrome.

PubMed

Niarchou, Maria; Moore, Tyler M; Tang, Sunny X; Calkins, Monica E; McDonald-McGuinn, Donna M; Zackai, Elaine H; Emanuel, Beverly S; Gur, Ruben C; Gur, Raquel E

2017-09-01

22q11.2 Deletion Syndrome (22q11.2DS) is one of the strongest known genetic risk factors for developing schizophrenia. Individuals with 22q11.2DS have high rates of neurodevelopmental disorders in childhood, while in adulthood ∼25% develop schizophrenia. Similar to the general population, high rates of comorbidity are common in 22q11.2DS. Employing a dimensional approach where psychopathology is examined at the symptom-level as complementary to diagnostic categories in a population at such high genetic risk for schizophrenia can help gain a better understanding of how psychopathology is structured as well as its genetic underpinnings. This is the first study to examine the dimensional structure of a wide spectrum of psychopathology in the context of a homogeneous genetic etiology like 22q11.2DS. We evaluated 331 individuals with 22q11.2DS, mean age (SD) = 16.9(8.7); 51% males, who underwent prospective comprehensive phenotyping. We sought to replicate previous findings by examining a bi-factor model that derives a general factor of psychopathology in addition to more specific dimensions of psychopathology (i.e., internalizing, externalizing and thought disorder). Psychopathology in 22q11.2DS was divided into one 'general psychopathology' factor and four specific dimensions (i.e., 'anxiety', 'mood', 'ADHD' and 'psychosis'). The 'psychosis' symptoms loaded strongly on the 'general psychopathology' factor. The similarity of the symptom structure of psychopathology between 22q11.2DS and community and clinical populations without the deletion indicate that 22q11.2DS can provide a model to explore alternative approaches to our current nosology. Our findings add to a growing literature indicating the need to reorganize current diagnostic classification systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chesapeake Bay Tidal Flooding Study. Appendix D. Social and Cultural Resources. Appendix E. Engineering Design and Cost Estimates. Appendix F. Economics.

DTIC Science & Technology

1984-09-01

provided by private airline. Facilities and services include fuel, storage and outside tiedown, instruction, rental planes, unicorn radio and aircraft...project the population to grow between 41 and 44.5 percent from 1980 to 2030. The greatest increases in population are anticipated for Chesapeake and...VIRGINIA DEMOGRAPHIC CHARACTERISTICS Poquoson has been one of the fastest growing cities in Virginia over the past 20 years. While the surrounding

Spatio-temporal variations in age structures of a partially re-established population of northern river otters (Lontra canadensis)

USGS Publications Warehouse

Barrett, Dominic A.; Leslie, David M.

2012-01-01

Examination of age structures and sex ratios is useful in the management of northern river otters (Lontra canadensis) and other furbearers. Reintroductions and subsequent recolonizations of river otters have been well documented, but changes in demographics between expanding and established populations have not been observed. As a result of reintroduction efforts, immigration from Arkansas and northeastern Texas, and other efforts, river otters have become partially reestablished throughout eastern and central Oklahoma. Our objective was to examine age structures of river otters in Oklahoma and identify trends that relate to space (watersheds, county) and time (USDA Animal and Plant Health Inspection Service county trapping records). We predicted that river otters in western areas of the state were younger than river otters occurring farther east. From 2005–2007, we obtained salvaged river otter carcasses from federal and state agencies, and we live-captured other river otters using leg hold traps. Seventy-two river otters were sampled. Overall, sex ratios were skewed toward females (1F∶0.8M), but they did not differ among spatiotemporal scales examined. Teeth were removed from salvaged and live-captured river otters (n  =  63) for aging. One-year old river otters represented the largest age class (30.2%). Proportion of juveniles (<1 y old) in Oklahoma (19.0%) was less than other states. Mean age of river otters decreased from east-to-west in the Arkansas River and its tributaries. Mean age of river otters differed between the Canadian River Watershed (0.8 y) and the Arkansas River Watershed (2.9 y) and the Canadian River Watershed and the Red River Watershed (2.4 y). Proportion of juveniles did not differ among spatiotemporal scales examined. Similar to age structure variations in other mammalian carnivores, colonizing or growing western populations of river otters in Oklahoma contained younger ages than more established eastern populations.

Mercy health promoters: a paradigm for implementing third world practices for resource-poor conditions of the developed world.

PubMed

Clark, Peter A; Surry, Luke

2007-03-01

The foreign-born population in the United States, according to the "Current Populations Report" published in 2004, is estimated to exceed 33.5 million, or "11.7 percent of the U.S. population". The increase in foreign-born peoples and their need for health care is a complicated issue facing many cities, health systems and hospitals. Over the course of the past few years Mercy Hospital of Philadelphia has treated increasing numbers of foreign-born African patients. The majority have been presenting in the late stages of disease. The increase of foreign-born documented and undocumented African patients seen by Mercy Hospital seems to reflect a foreign-born population "boom" in Philadelphia over the past decade. To meet the needs of this growing population, the Mercy Hospital Task Force on African Immigration designed a program that centers on the developing world concept of "Health Promoters". This program is intended to serve as one possible solution for hospitals to cost-effectively manage the care of this growing percentage of foreign-born individuals in the population. This notion of a "Health Promoter" program in Philadelphia is unique as one of those rare occasions when a developing world concept is being utilized in a developed world environment. It is also unique in that it can serve as a paradigm for other hospitals in the United States to meet the growing need of health care for the undocumented population.

Auxotrophic Actinobacillus pleurpneumoniae grows in multispecies biofilms without the need for nicotinamide-adenine dinucleotide (NAD) supplementation.

PubMed

Loera-Muro, Abraham; Jacques, Mario; Avelar-González, Francisco J; Labrie, Josée; Tremblay, Yannick D N; Oropeza-Navarro, Ricardo; Guerrero-Barrera, Alma L

2016-06-27

Actinobacillus pleuropneumoniae is the etiologic agent of porcine contagious pleuropneumonia, which causes important worldwide economic losses in the swine industry. Several respiratory tract infections are associated with biofilm formation, and A. pleuropneumoniae has the ability to form biofilms in vitro. Biofilms are structured communities of bacterial cells enclosed in a self-produced polymer matrix that are attached to an abiotic or biotic surface. Virtually all bacteria can grow as a biofilm, and multi-species biofilms are the most common form of microbial growth in nature. The goal of this study was to determine the ability of A. pleuropneumoniae to form multi-species biofilms with other bacteria frequently founded in pig farms, in the absence of pyridine compounds (nicotinamide mononucleotide [NMN], nicotinamide riboside [NR] or nicotinamide adenine dinucleotide [NAD]) that are essential for the growth of A. pleuropneumoniae. For the biofilm assay, strain 719, a field isolate of A. pleuropneumoniae serovar 1, was mixed with swine isolates of Streptococcus suis, Bordetella bronchiseptica, Pasteurella multocida, Staphylococcus aureus or Escherichia coli, and deposited in 96-well microtiter plates. Based on the CFU results, A. pleuropneumoniae was able to grow with every species tested in the absence of pyridine compounds in the culture media. Interestingly, A. pleuropneumoniae was also able to form strong biofilms when mixed with S. suis, B. bronchiseptica or S. aureus. In the presence of E. coli, A. pleuropneumoniae only formed a weak biofilm. The live and dead populations, and the matrix composition of multi-species biofilms were also characterized using fluorescent markers and enzyme treatments. The results indicated that poly-N-acetyl-glucosamine remains the primary component responsible for the biofilm structure. In conclusion, A. pleuropneumoniae apparently is able to satisfy the requirement of pyridine compounds through of other swine pathogens by cross-feeding, which enables A. pleuropneumoniae to grow and form multi-species biofilms.

Language Discordance and Patient-Centered Care in Occupational Therapy: A Case Study

PubMed Central

Martinez, Jenny; Leland, Natalie

2017-01-01

The accumulative burden of a growing non-English speaking minority population and health disparities in the United States demonstrate the urgency of examining occupational therapy practices and defining care that is timely, effective, safe, and patient-centered. In this context, we investigate an occupational therapy episode of care from the perspectives of patient, caregiver, and primary occupational therapy care provider. Treatment sessions were observed and one-on-one semi-structured interviews were conducted with the participants. Several themes describing areas of concern in communication and care delivery emerged, including expectations for care, the therapy relationship, professional identity, and pragmatic constraints. The use of untrained interpreters compromised treatment effectiveness and safety. This case highlights potential areas of concern in therapy when working with a diverse patient population. Abundant opportunities exist for occupational therapy to situate itself as an equitable, responsive, valuable, and essential service. PMID:26460475

Preliminary Assessment of New Orbital Debris Shielding for Unmanned Satellites

NASA Astrophysics Data System (ADS)

Wilkinson, J.; Stokes, H.; Walker, R.

The numerous rocket launches and spacecraft deployments carried out since the dawn of the space age have generated a large orbiting population of man-made debris. Without the adoption of mitigation measures, it is likely that this population will continue to increase in the future. The ever-growing collision threat posed to operating spacecraft from these debris objects is therefore fast becoming a driver in the design of new spacecraft missions. DERA, under contract from the European Space Agency (ESA), is developing new techniques to provide mass- and cost-effective solutions to this spacecraft protection problem. Direct shielding methods such as enhancing a spacecraft's thermal blankets with strong materials and adapting the honeycomb panel structure are being investigated, as are indirect shielding methods such as reconfiguration of critical or susceptible units. This paper reports the latest results of the direct shielding research.

Determinants of childhood obesity: need for a trans-sectoral convergent approach.

PubMed

Kiranmala, Naorem; Das, Manoja K; Arora, Narendra K

2013-03-01

The emerging burden of non communicable diseases is likely to erode the "Demographic-Dividend" of India and compromise the national growth and development. Increasing rates of childhood obesity globally and in India is a cause for serious public health concern. It is becoming increasingly apparent that obesity is result of complex interplay between multiple genes, environmental factors and human behavior. Clear comprehension of this interaction and pathway is still not clear, making the prevention and management of obesity especially challenging. Globalization and rapid economic growth has led to dramatic changes in the life style of the population including food intake, physical activity, market, environmental factors and social structures. A growing economy, urbanization and motorized transport have increased physical inactivity. A systematic multi-sectoral approach with population health as the center of discourse and attention is the only key to tackle this problem.

Challenges and Opportunities for Developing and Implementing Incentives to Improve Health-Related Behaviors in Older Adults

PubMed Central

Klein, Eran; Karlawish, Jason

2010-01-01

There is growing interest in using patient-directed incentives to change health-related behaviors. Advocates of incentive programs have proposed an ambitious research agenda for moving patient incentive programs forward. Older adults may pose a challenge to such a research agenda. The cognitive and psychological features of this population, in particular, age-related changes in emotional regulation, executive function and cognitive capacities, and a preference for collaborative decision-making raise questions about the suitability of these programs, particularly the structure of current financial incentives, to older adults. Differences in decision-making in older adults need to be accounted for in the design and implementation of financial incentive programs. Financial incentive programs tailored to characteristics of older adult populations may be more likely to improve the lives of older persons and the economic success of programs that serve them. PMID:20863335

Cryptic sexual populations account for genetic diversity and ecological success in a widely distributed, asexual fungus-growing ant.

PubMed

Rabeling, Christian; Gonzales, Omar; Schultz, Ted R; Bacci, Maurício; Garcia, Marcos V B; Verhaagh, Manfred; Ishak, Heather D; Mueller, Ulrich G

2011-07-26

Sex and recombination are central processes in life generating genetic diversity. Organisms that rely on asexual propagation risk extinction due to the loss of genetic diversity and the inability to adapt to changing environmental conditions. The fungus-growing ant species Mycocepurus smithii was thought to be obligately asexual because only parthenogenetic populations have been collected from widely separated geographic localities. Nonetheless, M. smithii is ecologically successful, with the most extensive distribution and the highest population densities of any fungus-growing ant. Here we report that M. smithii actually consists of a mosaic of asexual and sexual populations that are nonrandomly distributed geographically. The sexual populations cluster along the Rio Amazonas and the Rio Negro and appear to be the source of independently evolved and widely distributed asexual lineages, or clones. Either apomixis or automixis with central fusion and low recombination rates is inferred to be the cytogenetic mechanism underlying parthenogenesis in M. smithii. Males appear to be entirely absent from asexual populations, but their existence in sexual populations is indicated by the presence of sperm in the reproductive tracts of queens. A phylogenetic analysis of the genus suggests that M. smithii is monophyletic, rendering a hybrid origin of asexuality unlikely. Instead, a mitochondrial phylogeny of sexual and asexual populations suggests multiple independent origins of asexual reproduction, and a divergence-dating analysis indicates that M. smithii evolved 0.5-1.65 million years ago. Understanding the evolutionary origin and maintenance of asexual reproduction in this species contributes to a general understanding of the adaptive significance of sex.

Structure and Origin of Xanthomonas arboricola pv. pruni Populations Causing Bacterial Spot of Stone Fruit Trees in Western Europe.

PubMed

Boudon, Sylvain; Manceau, Charles; Nottéghem, Jean-Loup

2005-09-01

ABSTRACT Xanthomonas arboricola pv. pruni, the causal agent of bacterial spot on stone fruit, was found in 1995 in several orchards in southeastern France. We studied population genetics of this emerging pathogen in comparison with populations from the United States, where the disease was first described, and from Italy, where the disease has occurred since 1920. Four housekeeping genes (atpD, dnaK, efp, and glnA) and the intergenic transcribed spacer region were sequenced from a total of 3.9 kb of sequences, and fluorescent amplified fragment length polymorphism (FAFLP) analysis was performed. A collection of 64 X. arboricola pv. pruni strains, including 23 strains from France, was analyzed. The X. arboricola pv. pruni population had a low diversity because no sequence polymorphisms were observed. Population diversity revealed by FAFLP was lower for the West European population than for the American population. The same bacterial genotype was detected from five countries on three continents, a geographic distribution that can be explained by human-aided migration of bacteria. Our data support the hypothesis that the pathogen originated in the United States and subsequently has been disseminated to other stone-fruit-growing regions of the world. In France, emergence of this disease was due to a recent introduction of the most prevalent genotype of the bacterium found worldwide.

[Population pressure: a factor of political destabilization].

PubMed

Tallon, F

1993-04-01

Political stability throughout the world appears to be greater in countries with slowly growing populations than in those with rapid growth. Population is not the only influence on political stability, however. The relationship between political stability and development is strong. The rich countries with the slowest growth are the most stable, while poor developing countries with rapid growth suffer from chronic instability. Demographic pressure and density are not the same thing and must be distinguished. A fragile environment like that of the Sahel will experience demographic pressure despite low density. Japan has a greater population density than Rwanda and little cultivable land, but the population has a high standard of living. demographic pressure is not comparable in Japan and Rwanda because Japan has slow population growth and stable democratic political institutions. The rate of growth seems to be a more important element in destabilization than density. Rapid growth creates enormous political tensions especially when profound ethnic divisions exist, and it complicates problems of government by encouraging rapid urbanization. The unbalanced age structures resulting from rapid growth hinder the satisfaction of employment, educational, and health care needs for the ever-increasing masses of young people. 49% of Rwanda's population is under 15 and 66% is under 25. Rwanda is already densely populated, with around 300 inhabitants/sq km, and its population is projected to double in 20 years. 95% of the population is dependent on agriculture, but by 1988 the average landholding per family was only 1.25 hectares and 58% of families did not grown sufficient food for household needs. Further reduction in the size of holdings or a growing landless population will have multiple consequences. Urban migration will inevitably increase, bringing with it all the problems so evident in other poor countries where the process is more advanced than in Rwanda. Chaotic urbanization is in itself a destabilizing force. The phenomenon of potential political destabilization due to demographic pressure had been analyzed according to different criteria. Unconstitutional sudden changes of government, incomplete civil and political liberties, violent conflicts between ethnic and other subgroups, and the frustrated aspirations of large numbers of young persons are among possible indicators of political instability. A report by the Population Crisis committee which evaluated these indicators in different countries placed Rwanda 39th among 120 countries for potential destabilization. But the period of observation avoided the 1973 disturbances and the 1990 war in Rwanda. The results would undoubtedly be considerably less favorable if the period of observation extended to the present.

Host tree phenology affects vascular epiphytes at the physiological, demographic and community level

PubMed Central

Einzmann, Helena J. R.; Beyschlag, Joachim; Hofhansl, Florian; Wanek, Wolfgang; Zotz, Gerhard

2015-01-01

The processes that govern diverse tropical plant communities have rarely been studied in life forms other than trees. Structurally dependent vascular epiphytes, a major part of tropical biodiversity, grow in a three-dimensional matrix defined by their hosts, but trees differ in their architecture, bark structure/chemistry and leaf phenology. We hypothesized that the resulting seasonal differences in microclimatic conditions in evergreen vs. deciduous trees would affect epiphytes at different levels, from organ physiology to community structure. We studied the influence of tree leaf phenology on vascular epiphytes on the Island of Barro Colorado, Panama. Five tree species were selected, which were deciduous, semi-deciduous or evergreen. The crowns of drought-deciduous trees, characterized by sunnier and drier microclimates, hosted fewer individuals and less diverse epiphyte assemblages. Differences were also observed at a functional level, e.g. epiphyte assemblages in deciduous trees had larger proportions of Crassulacean acid metabolism species and individuals. At the population level a drier microclimate was associated with lower individual growth and survival in a xerophytic fern. Some species also showed, as expected, lower specific leaf area and higher δ13C values when growing in deciduous trees compared with evergreen trees. As hypothesized, host tree leaf phenology influences vascular epiphytes at different levels. Our results suggest a cascading effect of tree composition and associated differences in tree phenology on the diversity and functioning of epiphyte communities in tropical lowland forests. PMID:25392188

A Stable Urban Ecosystem

ERIC Educational Resources Information Center

Meier, Richard L.

1976-01-01

Describes a model for the future evolution of a stable ecosystem in a densely-populated society. Discusses designs for limiting population growth, resource-conserving settlements, and ways to feed growing cities. (MLH)

Extra-cardiac manifestations of adult congenital heart disease.

PubMed

Gaeta, Stephen A; Ward, Cary; Krasuski, Richard A

2016-10-01

Advancement in correction or palliation of congenital cardiac lesions has greatly improved the lifespan of congenital heart disease patients, resulting in a rapidly growing adult congenital heart disease (ACHD) population. As this group has increased in number and age, emerging science has highlighted the systemic nature of ACHD. Providers caring for these patients are tasked with long-term management of multiple neurologic, pulmonary, hepatic, renal, and endocrine manifestations that arise as syndromic associations with congenital heart defects or as sequelae of primary structural or hemodynamic abnormalities. In this review, we outline the current understanding and recent research into these extra-cardiac manifestations. Copyright © 2016 Elsevier Inc. All rights reserved.

Manual-based cognitive behavioral and cognitive rehabilitation therapy for young-onset dementia: a case report.

PubMed

Tonga, Johanne Bjoernstad; Arnevik, Espen Ajo; Werheid, Katja; Ulstein, Ingun Dina

2016-03-01

There is a growing attention worldwide to young-onset dementia (YOD) and this group's special challenges and needs. The literature on psychosocial interventions for this population is scarce, and little is known about the specific challenges and benefits of working therapeutically with this group of patients. The aim of this study was to explore if a manual-based structured cognitive behavioral/cognitive rehabilitation program would be beneficial for these patients. One case, a 63-year-old woman with YOD, is presented to illustrate how this intervention can be applied to individual patients to manage depressive symptoms in YOD.

Religion and HIV/AIDS stigma in Puerto Rico: a cultural challenge for training future physicians.

PubMed

Varas-Díaz, Nelson; Neilands, Torsten B; Cintrón-Bou, Francheska; Santos-Figueroa, Axel; Marzán-Rodríguez, Melissa; Marques, Domingo

2014-01-01

HIV/AIDS stigma continues to be a challenge for HIV prevention and treatment. When health professionals manifest stigma it can limit access to quality treatment. With an ever-growing epidemic among Latinos, including Puerto Ricans living on the Caribbean Island, the social and structural factors that foster HIV/AIDS stigma need to be understood. In this study, we documented the association of religion with HIV/AIDS stigma in a sample of medical students in Puerto Rico. Findings suggest that importance placed on religion, and participation in religious activities, is associated with HIV/AIDS stigma for this population.

Exploring Migratory Dynamics on HIV Transmission: The Case of Mexicans in New York City and Puebla, Mexico

PubMed Central

Guilamo-Ramos, Vincent; McCarthy, Katharine; Muñoz-Laboy, Miguel A.; de Lourdes Rosas López, Maria

2014-01-01

Migration and population movement are increasingly viewed as important factors associated with HIV transmission risk. With growing awareness of the potential impact of migration on HIV transmission, several perspectives have emerged that posit differing dynamics of risk. We considered available data on the role of migration on HIV transmission among Mexican migrants in New York City and Puebla, Mexico. Specifically, we examined 3 distinct models of migratory dynamics of HIV transmission—namely, the structural model, the local contextual model, and the interplay model. In doing so, we reframed current public health perspectives on the role of migration on HIV transmission. PMID:24825203

Religion and HIV/AIDS Stigma in Puerto Rico: A Cultural Challenge for Training Future Physicians

PubMed Central

Varas-Díaz, Nelson; Neilands, Torsten B.; Cintrón-Bou, Francheska; Santos-Figueroa, Axel; Marzán-Rodríguez, Melissa; Marques, Domingo

2014-01-01

HIV/AIDS stigma continues to be a challenge for HIV prevention and treatment. When health professionals manifest stigma it can limit access to quality treatment. With an ever-growing epidemic among Latinos, including Puerto Ricans living on the Caribbean Island, the social and structural factors that foster HIV/AIDS stigma need to be understood. In this study, we documented the association of religion with HIV/AIDS stigma in a sample of medical students in Puerto Rico. Findings suggest that importance placed on religion, and participation in religious activities, is associated with HIV/AIDS stigma for this population. PMID:23442492

Predator cannibalism can intensify negative impacts on heterospecific prey.

PubMed

Takatsu, Kunio; Kishida, Osamu

2015-07-01

Although natural populations consist of individuals with different traits, and the degree of phenotypic variation varies among populations, the impact of phenotypic variation on ecological interactions has received little attention, because traditional approaches to community ecology assume homogeneity of individuals within a population. Stage structure, which is a common way of generating size and developmental variation within predator populations, can drive cannibalistic interactions, which can affect the strength of predatory effects on the predator's heterospecific prey. Studies have shown that predator cannibalism weakens predatory effects on heterospecific prey by reducing the size of the predator population and by inducing less feeding activity of noncannibal predators. We predict, however, that predator cannibalism, by promoting rapid growth of the cannibals, can also intensify predation pressure on heterospecific prey, because large predators have large resource requirements and may utilize a wider variety of prey species. To test this hypothesis, we conducted an experiment in which we created carnivorous salamander (Hynobius retardatus) populations with different stage structures by manipulating the salamander's hatch timing (i.e., populations with large or small variation in the timing of hatching), and explored the resultant impacts on the abundance, behavior, morphology, and life history of the salamander's large heterospecific prey, Rana pirica frog tadpoles. Cannibalism was rare in salamander populations having small hatch-timing variation, but was frequent in those having large hatch-timing variation. Thus, giant salamander cannibals occurred only in the latter. We clearly showed that salamander giants exerted strong predation pressure on frog tadpoles, which induced large behavioral and morphological defenses in the tadpoles and caused them to metamorphose late at large size. Hence, predator cannibalism arising from large variation in the timing of hatching can strengthen predatory effects on heterospecific prey and can have impacts on various, traits of both predator and prey. Because animals commonly broaden their diet as they grow, such negative impacts of predator cannibalism on the heterospecific prey may be common in interactions between predators and prey species of similar size.

The Establishment of Genetically Engineered Canola Populations in the U.S.

PubMed Central

Schafer, Meredith G.; Ross, Andrew A.; Londo, Jason P.; Burdick, Connie A.; Lee, E. Henry; Travers, Steven E.; Van de Water, Peter K.; Sagers, Cynthia L.

2011-01-01

Concerns regarding the commercial release of genetically engineered (GE) crops include naturalization, introgression to sexually compatible relatives and the transfer of beneficial traits to native and weedy species through hybridization. To date there have been few documented reports of escape leading some researchers to question the environmental risks of biotech products. In this study we conducted a systematic roadside survey of canola (Brassica napus) populations growing outside of cultivation in North Dakota, USA, the dominant canola growing region in the U.S. We document the presence of two escaped, transgenic genotypes, as well as non-GE canola, and provide evidence of novel combinations of transgenic forms in the wild. Our results demonstrate that feral populations are large and widespread. Moreover, flowering times of escaped populations, as well as the fertile condition of the majority of collections suggest that these populations are established and persistent outside of cultivation. PMID:21998689

Arthroplasty Utilization in the United States is Predicted by Age-Specific Population Groups.

PubMed

Bashinskaya, Bronislava; Zimmerman, Ryan M; Walcott, Brian P; Antoci, Valentin

2012-01-01

Osteoarthritis is a common indication for hip and knee arthroplasty. An accurate assessment of current trends in healthcare utilization as they relate to arthroplasty may predict the needs of a growing elderly population in the United States. First, incidence data was queried from the United States Nationwide Inpatient Sample from 1993 to 2009. Patients undergoing total knee and hip arthroplasty were identified. Then, the United States Census Bureau was queried for population data from the same study period as well as to provide future projections. Arthroplasty followed linear regression models with the population group >64 years in both hip and knee groups. Projections for procedure incidence in the year 2050 based on these models were calculated to be 1,859,553 cases (hip) and 4,174,554 cases (knee). The need for hip and knee arthroplasty is expected to grow significantly in the upcoming years, given population growth predictions.

Do persistently fast-growing juveniles contribute disproportionately to population growth? A new analysis tool for matrix models and its application to rainforest trees.

PubMed

Zuidema, Pieter A; Brienen, Roel J W; During, Heinjo J; Güneralp, Burak

2009-11-01

Plants and animals often exhibit strong and persistent growth variation among individuals within a species. Persistently fast-growing individuals have a higher chance of reaching reproductive size, do so at a younger age, and therefore contribute disproportionately to population growth (lambda). Here we introduce a new approach to quantify this "fast-growth effect." We propose using age-size-structured matrix models in which persistently fast and slow growers are distinguished as they occur in relatively young and old age classes for a given size category. Life-cycle pathways involving fast growth can then be identified, and their contribution to lambda is quantified through loop analysis. We applied this approach to an example species, the tropical rainforest tree Cedrela odorata, that shows persistent growth variation among individuals. Loop analysis showed that juvenile trees reaching the 10-cm diameter class at below-median age contributed twice as much to lambda as slow juvenile growers. Fast growth to larger-diameter categories also contributed disproportionately to lambda. The results were robust to changes in parameter values and life-history trade-offs. These results show that the fast-growth effect can be strong in long-lived species. Persistent growth differences among individuals should therefore be accommodated for in demographic models and life-history studies.

Adverse Impact of Electromagnetic Radiation on Urban Environment and Natural Resources using Optical Sensors

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Katiyar, Swati; Rani, Meenu

2016-07-01

We are living in the age of a rapidly growing population and changing environmental conditions with an advance technical capacity.This has resulted in wide spread land cover change. One of the main causes for increasing urban heat is that more than half of the world's population lives in a rapidly growing urbanized environment. Satellite data can be highly useful to map change in land cover and other environmental phenomena with the passage of time. Among several human-induced environmental and urban thermal problems are reported to be negatively affecting urban residents in many ways. The built-up structures in urbanized areas considerably alter land cover thereby affecting thermal energy flow which leads to development of elevated surface and air temperature. The phenomenon Urban Heat Island implies 'island' of high temperature in cities, surrounded by relatively lower temperature in rural areas. The UHI for the temporal period is estimated using geospatial techniques which are then utilized for the impact assessment on climate of the surrounding regions and how it reduce the sustainability of the natural resources like air, vegetation. The present paper describes the methodology and resolution dynamic urban heat island change on climate using the geospatial approach. NDVI were generated using day time LANDSAT ETM+ image of 1990, 2000 and 2013. Temperature of various land use and land cover categories was estimated. Keywords: NDVI, Surface temperature, Dynamic changes.

Political violence, ethnic conflict, and contemporary wars: broad implications for health and social well-being.

PubMed

Pedersen, Duncan

2002-07-01

Ethnic conflict, political violence and wars that presently shape many parts of world have deep-seated structural causes. In poor and highly indebted countries, economic and environmental decline, asset depletion, and erosion of the subsistence base lead to further impoverishment and food insecurity for vast sectors of the population. Growing ethnic and religious tensions over a shrinking resource base often escort the emergence of predatory practices, rivalry, political violence, and internal wars. The nature of armed conflict has changed substantially over time and most strategic analysts agree that in the second half of the 20th century, contemporary wars are less of a problem of relations between states than a problem within states. Despite the growing number of armed conflicts and wars throughout the world, not enough attention has been paid to the local patterns of distress being experienced and the long-term health impact and psychosocial consequences of the various forms of political violence against individuals, communities, or specific ethnic groups. The short or long-term impact assessment on civilian populations of poor countries affected by war have been scarce, and studies focussing on experiences of collective suffering and trauma-related disorders among survivors are beginning to emerge in the scientific literature. The medicalization of collective suffering and trauma reflects a poor understanding of the relationships among critically important social determinants and the range of possible health outcomes of political violence.

The Hispanic Population: 1990-2000 Growth and Change.

ERIC Educational Resources Information Center

Guzman, Betsy; McConnell, Eileen Diaz

2002-01-01

Points out significant changes in the Hispanic population between 1990 and 2000. Explores changes in the size and distribution of the Latino population using short-form data from the 1990 and 2000 censuses. Indicates significant growth of the Hispanic population who identify as 'other' Latino and the growing importance of the Midwest and South as…

Population Dynamics of Empoasca fabae (Hemiptera: Cicadellidae) in Central Iowa Alfalfa Fields

PubMed Central

Weiser Erlandson, L. A.; Obrycki, J. J.

2015-01-01

Adults and nymphs of Empoasca fabae Harris (Hemiptera: Cicadellidae) and adults of predatory species in the families Coccinellidae, Anthocoridae, Nabidae, Chrysopidae, and Hemerobiidae were sampled in Iowa alfalfa fields from June to September in 1999 and 2000. The relationship between each predatory taxa and E. fabae was examined using regression analysis. In 2000, all predators were found to be positively correlated with the presence of E. fabae during all periods sampled and most likely contributed to mortality. Orius insidiosus (Say) (Hemiptera: Anthoridae) was the most numerous insect predatory species; population numbers ranged from 0 to 1 and 0.1 to 3.7 adults per 0.25 m2 in 1999 and 2000, respectively. Partial life tables were constructed for E. fabae nymphs for two alfalfa-growing periods. Nymphs were grouped into three age intervals: first and second, third and fourth, and fifth instars. For the first alfalfa growing period examined, E. fabae nymphal mortality was 70% in 1999 and 49% in 2000. During the last growing period of each season (August–September), total nymphal mortality was relatively low (<25%). Adult E. fabae density ranged from 5.4 to 25.6 and 1.4–9.2 per 0.25 m2 in 1999 and 2000, respectively. E. fabae population peaks were similar for each age interval in all growing periods. This study provides further information on the population dynamics of E. fabae and its relationship with select predatory species in Iowa alfalfa fields. PMID:26320260

Preliminary analysis of Greater Sage-grouse reproduction in the Virginia Mountains of northwestern Nevada

USGS Publications Warehouse

Coates, Peter S.; Lockyer, Zachary B.; Farinha, Melissa A.; Sweeney, Joelle M.; Johnson, Valerie M.; Meshriy, Matthew G.; Espinosa, Shawn P.; Delehanty, David J.; Casazza, Michael L.

2011-01-01

Relationships between habitat selection and population vital rates of greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse), recently designated as a candidate species under the Endangered Species Act, within the Great Basin are not well-understood. The growing development of renewable energy infrastructure within areas inhabited by sage-grouse is thought to influence predator and vegetation communities. For example, common ravens (Corvus corax), a synanthropic sage-grouse nest predator, are increasing range-wide and select transmission lines and other tall structures for nesting and perching. In the Virginia Mountains of northwestern Nevada, we collected preliminary information of space-use, habitat selection, and population vital rates during the nesting and brood-rearing period over two years on 56 sage-grouse. Additionally, videography at nest sites (n = 22) was used to identify sage-grouse nest predators. The study area is a potential site for renewable energy developments (i.e., wind and solar), and we plan to continue monitoring this population using a before-after-control-impact study design. The results reported here are preliminary and further data are required before conclusions can be drawn from this population of sage-grouse.

SPRINTT and the involvement of stakeholders: strategy and structure.

PubMed

Le Lain, Régis; Ignaszewski, Claire; Klingmann, Ingrid; Cesario, Alfredo; de Boer, Willem Ivo

2017-02-01

The current healthcare systems are built around the traditional paradigm of patients suffering from a single acute illness. They are, therefore, largely unprepared to face the increasing demands for health services arising from the expansion of an older population with specific medical needs related to multiple chronic disorders. As a consequence, the medical conditions of a large and growing segment of the older European population are not efficiently managed by the available healthcare services. In the context of an aging population, policy makers such as the European Commission and European Institutions, such as the European Medicines Agency (EMA), devote time and resources to study and accompany the need of the aging population. The EMA recognizes the importance of making sure that the needs of the Elderly are considered during development, approval, and use of new medicines, and, therefore, engages with healthcare professional organisations. The Sarcopenia and Physical Frailty in Older People: Multicomponent Intervention Strategies (SPRINTT) is the obvious result of these strategies. The present article describes the SPRINTT workpackage activities aimed at engaging the scientific discussion on the physical frailty and sarcopenia with the EMA as one of its interlocutor, acknowledging the need to collaborate on this topic to foster a productive dialogue.

CNVcaller: highly efficient and widely applicable software for detecting copy number variations in large populations.

PubMed

Wang, Xihong; Zheng, Zhuqing; Cai, Yudong; Chen, Ting; Li, Chao; Fu, Weiwei; Jiang, Yu

2017-12-01

The increasing amount of sequencing data available for a wide variety of species can be theoretically used for detecting copy number variations (CNVs) at the population level. However, the growing sample sizes and the divergent complexity of nonhuman genomes challenge the efficiency and robustness of current human-oriented CNV detection methods. Here, we present CNVcaller, a read-depth method for discovering CNVs in population sequencing data. The computational speed of CNVcaller was 1-2 orders of magnitude faster than CNVnator and Genome STRiP for complex genomes with thousands of unmapped scaffolds. CNV detection of 232 goats required only 1.4 days on a single compute node. Additionally, the Mendelian consistency of sheep trios indicated that CNVcaller mitigated the influence of high proportions of gaps and misassembled duplications in the nonhuman reference genome assembly. Furthermore, multiple evaluations using real sheep and human data indicated that CNVcaller achieved the best accuracy and sensitivity for detecting duplications. The fast generalized detection algorithms included in CNVcaller overcome prior computational barriers for detecting CNVs in large-scale sequencing data with complex genomic structures. Therefore, CNVcaller promotes population genetic analyses of functional CNVs in more species. © The Authors 2017. Published by Oxford University Press.

CNVcaller: highly efficient and widely applicable software for detecting copy number variations in large populations

PubMed Central

Wang, Xihong; Zheng, Zhuqing; Cai, Yudong; Chen, Ting; Li, Chao; Fu, Weiwei

2017-01-01

Abstract Background The increasing amount of sequencing data available for a wide variety of species can be theoretically used for detecting copy number variations (CNVs) at the population level. However, the growing sample sizes and the divergent complexity of nonhuman genomes challenge the efficiency and robustness of current human-oriented CNV detection methods. Results Here, we present CNVcaller, a read-depth method for discovering CNVs in population sequencing data. The computational speed of CNVcaller was 1–2 orders of magnitude faster than CNVnator and Genome STRiP for complex genomes with thousands of unmapped scaffolds. CNV detection of 232 goats required only 1.4 days on a single compute node. Additionally, the Mendelian consistency of sheep trios indicated that CNVcaller mitigated the influence of high proportions of gaps and misassembled duplications in the nonhuman reference genome assembly. Furthermore, multiple evaluations using real sheep and human data indicated that CNVcaller achieved the best accuracy and sensitivity for detecting duplications. Conclusions The fast generalized detection algorithms included in CNVcaller overcome prior computational barriers for detecting CNVs in large-scale sequencing data with complex genomic structures. Therefore, CNVcaller promotes population genetic analyses of functional CNVs in more species. PMID:29220491

Neglected populations: safeguarding the health of street-involved children in Ghana.

PubMed

Osei-Twum, Jo-Ann; Wasan, Kishor M

2012-10-01

Ensuring the health of street-involved children is a growing public health challenge. These children are vulnerable, neglected, and rarely a priority for basic service providers and governments. Sizable populations of street-involved children are present in major urban areas worldwide and current trends in urbanization suggest these populations will grow in the coming years. Although migration offers employment and training opportunities, the health and wellbeing of children is negatively impacted by their interactions with the streets. However, systemic barriers may also prevent these children from achieving an adequate health status. The situation of street-involved children in Ghana, West Africa will be discussed. Copyright © 2012 Wiley Periodicals, Inc.

'We are faced everywhere with a growing population': demographic change and the British state, 1955-64.

PubMed

O' Hara, Glen

2004-01-01

The early 1960s was a period of relative expansion for the welfare state, and the return to the use of planning techniques in macroeconomic policy. This has hitherto been explained by reference to a number of general causes. These have included party political electoral necessity, the need to gain popular support for the cold war by spreading the benefits of liberal capitalism, the power of welfare professionals, the growing realization that the post-war welfare state was not working as well as previously thought, and generational changes in politics and the civil service. Whilst not denying the importance of all these factors, this essay seeks to make clear the importance of another vital element in this story: the implications for the welfare state and the managed economy of the rise in the birth rate, and the perceived' population explosion', of the late 1950s and early 1960s. Statistical estimates are presented here that show just how large the implied expansion of the welfare state, and just how serious the pressure of a growing dependent population, would have been had the population predictions of the early 1930s proved to be accurate.

Preliminary validation of the Malay Yale Food Addiction Scale: Factor structure and item analysis in an obese population.

PubMed

Swarna Nantha, Yogarabindranath; Abd Patah, Norafidza Ashiquin; Ponnusamy Pillai, Mahalakshmi

2016-12-01

Researchers suggest that the rise in obesity rates may be explained by the addictive properties of certain types of food. In view of the growing obesity epidemic in South-East Asia, there is a need for a psychometric tool to assess the concept of food addiction amongst high-risk populations. The objective of this study is to translate the Yale Food Addiction Scale (YFAS) into the Malay language and subsequently validate its use in an obese population. Between the year 2014 and 2015, a total of 250 obese adults were assessed for food addiction utilizing the Malay version of the YFAS at a primary care clinic. An assessment of the psychometric properties of the scale was performed to determine the factor structure, item statistics and internal consistency of the scale. A one factorial structure of YFAS was confirmed in this study through factor analysis. All items except 4 (items 19, 22, 24 and 25) had factor loadings >0.42. The internal reliability (KR-20) coefficient of the one-factor solution was α = 0.76. The mean YFAS symptom count was M = 2.74 (SD = 1.57) with 10.4% (N = 26) of the participants received the diagnosis of food addiction. The determination of construct validity and the identification of other latent variables in the Malay food addiction model is necessary prior to the formal utilization of the scale as a tool to detect addictive eating patterns in the community. Copyright © 2016 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

Impacts of the Deepwater Horizon oil spill evaluated using an end-to-end ecosystem model.

PubMed

Ainsworth, Cameron H; Paris, Claire B; Perlin, Natalie; Dornberger, Lindsey N; Patterson, William F; Chancellor, Emily; Murawski, Steve; Hollander, David; Daly, Kendra; Romero, Isabel C; Coleman, Felicia; Perryman, Holly

2018-01-01

We use a spatially explicit biogeochemical end-to-end ecosystem model, Atlantis, to simulate impacts from the Deepwater Horizon oil spill and subsequent recovery of fish guilds. Dose-response relationships with expected oil concentrations were utilized to estimate the impact on fish growth and mortality rates. We also examine the effects of fisheries closures and impacts on recruitment. We validate predictions of the model by comparing population trends and age structure before and after the oil spill with fisheries independent data. The model suggests that recruitment effects and fishery closures had little influence on biomass dynamics. However, at the assumed level of oil concentrations and toxicity, impacts on fish mortality and growth rates were large and commensurate with observations. Sensitivity analysis suggests the biomass of large reef fish decreased by 25% to 50% in areas most affected by the spill, and biomass of large demersal fish decreased even more, by 40% to 70%. Impacts on reef and demersal forage caused starvation mortality in predators and increased reliance on pelagic forage. Impacts on the food web translated effects of the spill far away from the oiled area. Effects on age structure suggest possible delayed impacts on fishery yields. Recovery of high-turnover populations generally is predicted to occur within 10 years, but some slower-growing populations may take 30+ years to fully recover.

Seasonal reproduction leads to population collapse and an Allee effect in a stage-structured consumer-resource biomass model when mortality rate increases

PubMed Central

de Roos, André M.

2017-01-01

Many populations collapse suddenly when reaching low densities even if they have abundant food conditions, a phenomenon known as an Allee effect. Such collapses can have disastrous consequences, for example, for loss of biodiversity. In this paper, we formulate a stage-structured consumer-resource biomass model in which adults only reproduce at the beginning of each growing season, and investigate the effect of an increasing stage-independent background mortality rate of the consumer. As the main difference with previously studied continuous-time models, seasonal reproduction can result in an Allee effect and consumer population collapses at high consumer mortality rate. However, unlike the mechanisms reported in the literature, in our model the Allee effect results from the time difference between the maturation of juveniles and the reproduction of adults. The timing of maturation plays a crucial role because it not only determines the body size of the individuals at maturation but also influences the duration of the period during which adults can invest in reproductive energy, which together determine the reproductive output at the end of the season. We suggest that there exists an optimal timing of maturation and that consumer persistence is promoted if individuals mature later in the season at a larger body size, rather than maturing early, despite high food availability supporting rapid growth. PMID:29088273

Impacts of the Deepwater Horizon oil spill evaluated using an end-to-end ecosystem model

PubMed Central

Paris, Claire B.; Perlin, Natalie; Dornberger, Lindsey N.; Patterson, William F.; Chancellor, Emily; Murawski, Steve; Hollander, David; Daly, Kendra; Romero, Isabel C.; Coleman, Felicia; Perryman, Holly

2018-01-01

We use a spatially explicit biogeochemical end-to-end ecosystem model, Atlantis, to simulate impacts from the Deepwater Horizon oil spill and subsequent recovery of fish guilds. Dose-response relationships with expected oil concentrations were utilized to estimate the impact on fish growth and mortality rates. We also examine the effects of fisheries closures and impacts on recruitment. We validate predictions of the model by comparing population trends and age structure before and after the oil spill with fisheries independent data. The model suggests that recruitment effects and fishery closures had little influence on biomass dynamics. However, at the assumed level of oil concentrations and toxicity, impacts on fish mortality and growth rates were large and commensurate with observations. Sensitivity analysis suggests the biomass of large reef fish decreased by 25% to 50% in areas most affected by the spill, and biomass of large demersal fish decreased even more, by 40% to 70%. Impacts on reef and demersal forage caused starvation mortality in predators and increased reliance on pelagic forage. Impacts on the food web translated effects of the spill far away from the oiled area. Effects on age structure suggest possible delayed impacts on fishery yields. Recovery of high-turnover populations generally is predicted to occur within 10 years, but some slower-growing populations may take 30+ years to fully recover. PMID:29370187

Cell division in Escherichia coli cultures monitored at single cell resolution

PubMed Central

Roostalu, Johanna; Jõers, Arvi; Luidalepp, Hannes; Kaldalu, Niilo; Tenson, Tanel

2008-01-01

Background A fundamental characteristic of cells is the ability to divide. To date, most parameters of bacterial cultures, including cell division, have been measured as cell population averages, assuming that all bacteria divide at a uniform rate. Results We monitored the division of individual cells in Escherichia coli cultures during different growth phases. Our experiments are based on the dilution of green fluorescent protein (GFP) upon cell division, monitored by flow cytometry. The results show that the vast majority of E. coli cells in exponentially growing cultures divided uniformly. In cultures that had been in stationary phase up to four days, no cell division was observed. However, upon dilution of stationary phase culture into fresh medium, two subpopulations of cells emerged: one that started dividing and another that did not. These populations were detectable by GFP dilution and displayed different side scatter parameters in flow cytometry. Further analysis showed that bacteria in the non-growing subpopulation were not dead, neither was the difference in growth capacity reducible to differences in stationary phase-specific gene expression since we observed uniform expression of several stress-related promoters. The presence of non-growing persisters, temporarily dormant bacteria that are tolerant to antibiotics, has previously been described within growing bacterial populations. Using the GFP dilution method combined with cell sorting, we showed that ampicillin lyses growing bacteria while non-growing bacteria retain viability and that some of them restart growth after the ampicillin is removed. Thus, our method enables persisters to be monitored even in liquid cultures of wild type strains in which persister formation has low frequency. Conclusion In principle, the approaches developed here could be used to detect differences in cell division in response to different environmental conditions and in cultures of unicellular organisms other than E. coli. PMID:18430255

Exact Solutions of Coupled Multispecies Linear Reaction–Diffusion Equations on a Uniformly Growing Domain

PubMed Central

Simpson, Matthew J.; Sharp, Jesse A.; Morrow, Liam C.; Baker, Ruth E.

2015-01-01

Embryonic development involves diffusion and proliferation of cells, as well as diffusion and reaction of molecules, within growing tissues. Mathematical models of these processes often involve reaction–diffusion equations on growing domains that have been primarily studied using approximate numerical solutions. Recently, we have shown how to obtain an exact solution to a single, uncoupled, linear reaction–diffusion equation on a growing domain, 0 < x < L(t), where L(t) is the domain length. The present work is an extension of our previous study, and we illustrate how to solve a system of coupled reaction–diffusion equations on a growing domain. This system of equations can be used to study the spatial and temporal distributions of different generations of cells within a population that diffuses and proliferates within a growing tissue. The exact solution is obtained by applying an uncoupling transformation, and the uncoupled equations are solved separately before applying the inverse uncoupling transformation to give the coupled solution. We present several example calculations to illustrate different types of behaviour. The first example calculation corresponds to a situation where the initially–confined population diffuses sufficiently slowly that it is unable to reach the moving boundary at x = L(t). In contrast, the second example calculation corresponds to a situation where the initially–confined population is able to overcome the domain growth and reach the moving boundary at x = L(t). In its basic format, the uncoupling transformation at first appears to be restricted to deal only with the case where each generation of cells has a distinct proliferation rate. However, we also demonstrate how the uncoupling transformation can be used when each generation has the same proliferation rate by evaluating the exact solutions as an appropriate limit. PMID:26407013

Exact Solutions of Coupled Multispecies Linear Reaction-Diffusion Equations on a Uniformly Growing Domain.

PubMed

Simpson, Matthew J; Sharp, Jesse A; Morrow, Liam C; Baker, Ruth E

2015-01-01

Embryonic development involves diffusion and proliferation of cells, as well as diffusion and reaction of molecules, within growing tissues. Mathematical models of these processes often involve reaction-diffusion equations on growing domains that have been primarily studied using approximate numerical solutions. Recently, we have shown how to obtain an exact solution to a single, uncoupled, linear reaction-diffusion equation on a growing domain, 0 < x < L(t), where L(t) is the domain length. The present work is an extension of our previous study, and we illustrate how to solve a system of coupled reaction-diffusion equations on a growing domain. This system of equations can be used to study the spatial and temporal distributions of different generations of cells within a population that diffuses and proliferates within a growing tissue. The exact solution is obtained by applying an uncoupling transformation, and the uncoupled equations are solved separately before applying the inverse uncoupling transformation to give the coupled solution. We present several example calculations to illustrate different types of behaviour. The first example calculation corresponds to a situation where the initially-confined population diffuses sufficiently slowly that it is unable to reach the moving boundary at x = L(t). In contrast, the second example calculation corresponds to a situation where the initially-confined population is able to overcome the domain growth and reach the moving boundary at x = L(t). In its basic format, the uncoupling transformation at first appears to be restricted to deal only with the case where each generation of cells has a distinct proliferation rate. However, we also demonstrate how the uncoupling transformation can be used when each generation has the same proliferation rate by evaluating the exact solutions as an appropriate limit.

Ovary structure in a presocial insect, Elasmucha grisea (Heteroptera, Acanthosomatidae).

PubMed

Ogorzałek, Antoni; Trochimczuk, Artur

2009-11-01

First generation egg clusters of Elasmucha grisea are more closely guarded than second generation clusters. The ovaries of this species are structured to enhance this behavior. The population of E. grisea from S-W Poland breeds in the spring (May-June) and late summer (July-August). The second generation clutches contain fewer eggs and are destroyed 3-4 days after oviposition by predators and parasitoids. The ovary structure in the studied species differs from that found in other Heteroptera. The average number of ovarioles per ovary is 24 while in the other investigated species the number of ovarioles per ovary is 6-7. Lateral oviducts are elongated and the ovarioles are arranged in a pennate pattern. Each ovariole contains only one growing ovarian follicle. Differentiation of the ovarioles and ovarian follicles is synchronised thus enabling simultaneous oviposition. A comparative analysis of the ovary structure during the life cycle, particularly the presence of atresive ovarian follicles in the ovarioles of egg- and nymph guarding females, as well as the shape and structure of the apical part of the tropharium all support the hypothesis of cooperation between females in E. grisea. A similar ovary structure has been observed in the Coccoidea (Hemiptera, Homoptera) which indicates presocial behavior.

The DSM-5 Trait Measure in a Psychiatric Sample of Late Adolescents and Emerging Adults: Structure, Reliability, and Validity.

PubMed

De Caluwé, Elien; Verbeke, Lize; van Aken, Marcel; van der Heijden, Paul T; De Clercq, Barbara

2018-02-22

The inclusion of a dimensional trait model of personality pathology in DSM-5 creates new opportunities for research on developmental antecedents of personality pathology. The traits of this model can be measured with the Personality Inventory for DSM-5 (PID-5), initially developed for adults, but also demonstrating validity in adolescents. The present study adds to the growing body of literature on the psychometrics of the PID-5, by examining its structure, validity, and reliability in 187 psychiatric-referred late adolescents and emerging adults. PID-5, Big Five Inventory, and Kidscreen self-reports were provided, and 88 non-clinical matched controls completed the PID-5. Results confirm the PID-5's five-factor structure, indicate adequate psychometric properties, and underscore the construct and criterion validity, showing meaningful associations with adaptive traits and quality of life. Results are discussed in terms of the PID-5's applicability in vulnerable populations who are going through important developmental transition phases, such as the step towards early adulthood.

Kinship and the evolution of social behaviours in the sea

PubMed Central

Kamel, Stephanie J.; Grosberg, Richard K.

2013-01-01

Until recently, little attention has been paid to the existence of kin structure in the sea, despite the fact that many marine organisms are sessile or sedentary. This lack of attention to kin structure, and its impacts on social evolution, historically stems from the pervasive assumption that the dispersal of gametes and larvae is almost always sufficient to prevent any persistent associations of closely related offspring or adults. However, growing evidence, both theoretical and empirical, casts doubt on the generality of this assumption, not only in species with limited dispersal, but also in species with long dispersive phases. Moreover, many marine organisms either internally brood their progeny or package them in nurseries, both of which provide ample opportunities for kinship to influence the nature and outcomes of social interactions among family members. As the evidence for kin structure within marine populations mounts, it follows that kin selection may play a far greater role in the evolution of both behaviours and life histories of marine organisms than is presently appreciated. PMID:24132095

Kinship and the evolution of social behaviours in the sea.

PubMed

Kamel, Stephanie J; Grosberg, Richard K

2013-01-01

Until recently, little attention has been paid to the existence of kin structure in the sea, despite the fact that many marine organisms are sessile or sedentary. This lack of attention to kin structure, and its impacts on social evolution, historically stems from the pervasive assumption that the dispersal of gametes and larvae is almost always sufficient to prevent any persistent associations of closely related offspring or adults. However, growing evidence, both theoretical and empirical, casts doubt on the generality of this assumption, not only in species with limited dispersal, but also in species with long dispersive phases. Moreover, many marine organisms either internally brood their progeny or package them in nurseries, both of which provide ample opportunities for kinship to influence the nature and outcomes of social interactions among family members. As the evidence for kin structure within marine populations mounts, it follows that kin selection may play a far greater role in the evolution of both behaviours and life histories of marine organisms than is presently appreciated.

Networks and Models with Heterogeneous Population Structure in Epidemiology

NASA Astrophysics Data System (ADS)

Kao, R. R.

Heterogeneous population structure can have a profound effect on infectious disease dynamics, and is particularly important when investigating “tactical” disease control questions. At times, the nature of the network involved in the transmission of the pathogen (bacteria, virus, macro-parasite, etc.) appears to be clear; however, the nature of the network involved is dependent on the scale (e.g. within-host, between-host, or between-population), the nature of the contact, which ranges from the highly specific (e.g. sexual acts or needle sharing at the person-to-person level) to almost completely non-specific (e.g. aerosol transmission, often over long distances as can occur with the highly infectious livestock pathogen foot-and-mouth disease virus—FMDv—at the farm-to-farm level, e.g. Schley et al. in J. R. Soc. Interface 6:455-462, 2008), and the timescale of interest (e.g. at the scale of the individual, the typical infectious period of the host). Theoretical approaches to examining the implications of particular network structures on disease transmission have provided critical insight; however, a greater challenge is the integration of network approaches with data on real population structures. In this chapter, some concepts in disease modelling will be introduced, the relevance of selected network phenomena discussed, and then results from real data and their relationship to network analyses summarised. These include examinations of the patterns of air traffic and its relation to the spread of SARS in 2003 (Colizza et al. in BMC Med., 2007; Hufnagel et al. in Proc. Natl. Acad. Sci. USA 101:15124-15129, 2004), the use of the extensively documented Great Britain livestock movements network (Green et al. in J. Theor. Biol. 239:289-297, 2008; Robinson et al. in J. R. Soc. Interface 4:669-674, 2007; Vernon and Keeling in Proc. R. Soc. Lond. B, Biol. Sci. 276:469-476, 2009) and the growing interest in combining contact structure data with phylogenetics to identify real contact patterns as they directly relate to diseases of interest (Cottam et al. in PLoS Pathogens 4:1000050, 2007; Hughes et al. in PLoS Pathogens 5:1000590, 2009).

Oceanography promotes self-recruitment in a planktonic larval disperser.

PubMed

Teske, Peter R; Sandoval-Castillo, Jonathan; van Sebille, Erik; Waters, Jonathan; Beheregaray, Luciano B

2016-09-30

The application of high-resolution genetic data has revealed that oceanographic connectivity in marine species with planktonic larvae can be surprisingly limited, even in the absence of major barriers to dispersal. Australia's southern coast represents a particularly interesting system for studying planktonic larval dispersal, as the hydrodynamic regime of the wide continental shelf has potential to facilitate onshore retention of larvae. We used a seascape genetics approach (the joint analysis of genetic data and oceanographic connectivity simulations) to assess population genetic structure and self-recruitment in a broadcast-spawning marine gastropod that exists as a single meta-population throughout its temperate Australian range. Levels of self-recruitment were surprisingly high, and oceanographic connectivity simulations indicated that this was a result of low-velocity nearshore currents promoting the retention of planktonic larvae in the vicinity of natal sites. Even though the model applied here is comparatively simple and assumes that the dispersal of planktonic larvae is passive, we find that oceanography alone is sufficient to explain the high levels of genetic structure and self-recruitment. Our study contributes to growing evidence that sophisticated larval behaviour is not a prerequisite for larval retention in the nearshore region in planktonic-developing species.

Lightning Channel Corona Formation Treated as a Large System of Streamers

NASA Astrophysics Data System (ADS)

Carlson, B.; Lehtinen, N. G.; Kochkin, P.

2017-12-01

Transfer of charge along a lightning channel leads to strong electric fields that drive such charge outward. This charge flow is nonuniform, breaking up into millimeter-scale discharge structures called streamers. The motion of such streamers can carry charge many meters outward from the channel, but each individual streamer only carries a small amount of charge. Transfer of macroscopic charge outward thus requires a large population of streamers that are expected to interact and exhibit interesting collective behaviors. We attempt to simulate such collective behaviors by approximating the behavior of each streamer but retaining streamer interactions and overall electrodynamic effects and apply this simulation to a few key scenarios. For the case of flow of charge off a lightning channel, we simulate a continually growing population of streamers injected near a charged conducting channel. Further, motivated by lightning initiation, we simulate the growth of a population of streamers from a single seed streamer as might initiate from a hydrometeor. For all cases considered, we characterize the charges and currents involved, compare to observations where possible, and characterize the collective effects including spatial and temporal non-uniformity.

A new mechanistic approach for the further development of a population with established size bimodality

USGS Publications Warehouse

Heerman, Lisa; DeAngelis, Donald L.; Borcherding, Jost

2017-01-01

Usually, the origin of a within-cohort bimodal size distribution is assumed to be caused by initial size differences or by one discrete period of accelerated growth for one part of the population. The aim of this study was to determine if more continuous pathways exist allowing shifts from the small to the large fraction within a bimodal age-cohort. Therefore, a Eurasian perch population, which had already developed a bimodal size-distribution and had differential resource use of the two size-cohorts, was examined. Results revealed that formation of a bimodal size-distribution can be a continuous process. Perch from the small size-cohort were able to grow into the large size-cohort by feeding on macroinvertebrates not used by their conspecifics. The diet shifts were accompanied by morphological shape changes. Intra-specific competition seemed to trigger the development towards an increasing number of large individuals. A stage-structured matrix model confirmed these assumptions. The fact that bimodality can be a continuous process is important to consider for the understanding of ecological processes and links within ecosystems.

A new mechanistic approach for the further development of a population with established size bimodality

PubMed Central

DeAngelis, Donald L.; Borcherding, Jost

2017-01-01

Usually, the origin of a within-cohort bimodal size distribution is assumed to be caused by initial size differences or by one discrete period of accelerated growth for one part of the population. The aim of this study was to determine if more continuous pathways exist allowing shifts from the small to the large fraction within a bimodal age-cohort. Therefore, a Eurasian perch population, which had already developed a bimodal size-distribution and had differential resource use of the two size-cohorts, was examined. Results revealed that formation of a bimodal size-distribution can be a continuous process. Perch from the small size-cohort were able to grow into the large size-cohort by feeding on macroinvertebrates not used by their conspecifics. The diet shifts were accompanied by morphological shape changes. Intra-specific competition seemed to trigger the development towards an increasing number of large individuals. A stage-structured matrix model confirmed these assumptions. The fact that bimodality can be a continuous process is important to consider for the understanding of ecological processes and links within ecosystems. PMID:28650963

Potential effects of anthropogenic greenhouse gases on avian habitats and populations in the northern Great Plains

USGS Publications Warehouse

Larson, Diane L.

1994-01-01

Biotic response to the buildup of greenhouse gases in Earth's atmosphere is considerably more complex than an adjustment to changing temperature and precipitation. The fertilization effect carbon dioxide has on some plants, the impact UVB radiation has on health and productivity of organisms, and the resulting changes in competitive balance and trophic structure must also be considered. The intent of this paper is to review direct and indirect effects of anthropogenic greenhouse gases on wildlife, and to explore possible effects on populations of birds and their habitats in the northern Great Plains.Many of the potential effects of increasing greenhouse gases, such as declining plant nutritional value, changes in timing of insect emergence, and fewer and saltier wetlands, foreshadow a decline in avian populations on the Great Plains. However, other possible effects such as increased drought resistance and water use efficiency of vegetation, longer growing seasons, and greater overall plant biomass promise at least some mitigation. Effects of multiple simultaneous perturbations such as can be expected under doubled carbon dioxide scenarios will require substantial basic research to clarify.

Rapid evolution leads to differential population dynamics and top-down control in resurrected Daphnia populations.

PubMed

Goitom, Eyerusalem; Kilsdonk, Laurens J; Brans, Kristien; Jansen, Mieke; Lemmens, Pieter; De Meester, Luc

2018-01-01

There is growing evidence of rapid genetic adaptation of natural populations to environmental change, opening the perspective that evolutionary trait change may subsequently impact ecological processes such as population dynamics, community composition, and ecosystem functioning. To study such eco-evolutionary feedbacks in natural populations, however, requires samples across time. Here, we capitalize on a resurrection ecology study that documented rapid and adaptive evolution in a natural population of the water flea Daphnia magna in response to strong changes in predation pressure by fish, and carry out a follow-up mesocosm experiment to test whether the observed genetic changes influence population dynamics and top-down control of phytoplankton. We inoculated populations of the water flea D. magna derived from three time periods of the same natural population known to have genetically adapted to changes in predation pressure in replicate mesocosms and monitored both Daphnia population densities and phytoplankton biomass in the presence and absence of fish. Our results revealed differences in population dynamics and top-down control of algae between mesocosms harboring populations from the time period before, during, and after a peak in fish predation pressure caused by human fish stocking. The differences, however, deviated from our a priori expectations. An S-map approach on time series revealed that the interactions between adults and juveniles strongly impacted the dynamics of populations and their top-down control on algae in the mesocosms, and that the strength of these interactions was modulated by rapid evolution as it occurred in nature. Our study provides an example of an evolutionary response that fundamentally alters the processes structuring population dynamics and impacts ecosystem features.

Multiracial Families.

ERIC Educational Resources Information Center

Kenney, Kelley

The multiracial population is one of the fastest growing segments of the U. S. population. In discussing the multiracial population it is first important to identify and define the groups that are under the heading of multiracial. The literature has included interracial couples, multiracial individuals, and families in which a cross-racial or…

Effects of precipitation change and neighboring plants on population dynamics of Bromus tectorum.

PubMed

Prevéy, Janet S; Seastedt, Timothy R

2015-11-01

Shifting precipitation patterns resulting from global climate change will influence the success of invasive plant species. In the Front Range of Colorado, Bromus tectorum (cheatgrass) and other non-native winter annuals have invaded grassland communities and are becoming more abundant. As the global climate warms, more precipitation may fall as rain rather than snow in winter, and an increase in winter rain could benefit early-growing winter annuals, such as B. tectorum, to the detriment of native species. In this study we measured the effects of simulated changes in seasonal precipitation and presence of other plant species on population growth of B. tectorum in a grassland ecosystem near Boulder, Colorado, USA. We also performed elasticity analyses to identify life transitions that were most sensitive to precipitation differences. In both study years, population growth rates were highest for B. tectorum growing in treatments receiving supplemental winter precipitation and lowest for those receiving the summer drought treatment. Survival of seedlings to flowering and seed production contributed most to population growth in all treatments. Biomass of neighboring native plants was positively correlated with reduced population growth rates of B. tectorum. However, exotic plant biomass had no effect on population growth rates. This study demonstrates how interacting effects of climate change and presence of native plants can influence the population growth of an invasive species. Overall, our results suggest that B. tectorum will become more invasive in grasslands if the seasonality of precipitation shifts towards wetter winters and allows B. tectorum to grow when competition from native species is low.

Persistence of historical population structure in an endangered species despite near-complete biome conversion in California's San Joaquin Desert.

PubMed

Richmond, Jonathan Q; Wood, Dustin A; Westphal, Michael F; Vandergast, Amy G; Leaché, Adam D; Saslaw, Lawrence R; Butterfield, H Scott; Fisher, Robert N

2017-07-01

Genomic responses to habitat conversion can be rapid, providing wildlife managers with time-limited opportunities to enact recovery efforts that use population connectivity information that reflects predisturbance landscapes. Despite near-complete biome conversion, such opportunities may still exist for the endemic fauna and flora of California's San Joaquin Desert, but comprehensive genetic data sets are lacking for nearly all species in the region. To fill this knowledge gap, we studied the rangewide population structure of the endangered blunt-nosed leopard lizard Gambelia sila, a San Joaquin Desert endemic, using restriction site-associated DNA (RAD), microsatellite and mtDNA data to test whether admixture patterns and estimates of effective migration surfaces (EEMS) can identify land areas with high population connectivity prior to the conversion of native xeric habitats. Clustering and phylogenetic analyses indicate a recent shared history between numerous isolated populations and EEMS reveals latent signals of corridors and barriers to gene flow over areas now replaced by agriculture and urbanization. Conflicting histories between the mtDNA and nuclear genomes are consistent with hybridization with the sister species G. wislizenii, raising important questions about where legal protection should end at the southern range limit of G. sila. Comparative analysis of different data sets also adds to a growing list of advantages in using RAD loci for genetic studies of rare species. We demonstrate how the results of this work can serve as an evolutionary guidance tool for managing endemic, arid-adapted taxa in one of the world's most compromised landscapes. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Unraveling the efficiency of RAPD and SSR markers in diversity analysis and population structure estimation in common bean.

PubMed

Zargar, Sajad Majeed; Farhat, Sufia; Mahajan, Reetika; Bhakhri, Ayushi; Sharma, Arjun

2016-01-01

Increase in food production viz-a-viz quality of food is important to feed the growing human population to attain food as well as nutritional security. The availability of diverse germplasm of any crop is an important genetic resource to mine the genes that may assist in attaining food as well as nutritional security. Here we used 15 RAPD and 23 SSR markers to elucidate diversity among 51 common bean genotypes mostly landraces collected from the Himalayan region of Jammu and Kashmir, India. We observed that both the markers are highly polymorphic. The discriminatory power of these markers was determined using various parameters like; percent polymorphism, PIC, resolving power and marker index. 15 RAPDs produced 171 polymorphic bands, while 23 SSRs produced 268 polymorphic bands. SSRs showed a higher PIC value (0.300) compared to RAPDs (0.243). Further the resolving power of SSRs was 5.241 compared to 3.86 for RAPDs. However, RAPDs showed a higher marker index (2.69) compared to SSRs (1.279) that may be attributed to their higher multiplex ratio. The dendrograms generated with hierarchical UPGMA cluster analysis grouped genotypes into two main clusters with various degrees of sub clustering within the cluster. Here we observed that both the marker systems showed comparable accuracy in grouping genotypes of common bean according to their area of cultivation. The model based STRUCTURE analysis using 15 RAPD and 23 SSR markers identified a population with 3 sub-populations which corresponds to distance based groupings. High level of genetic diversity was observed within the population. These findings have further implications in common bean breeding as well as conservation programs.

The Indian "girl" psychology: A perspective.

PubMed

Rao, G Prasad; Vidya, K L; Sriramya, V

2015-07-01

India has one of the fastest growing youth populations in the world. Girls below 19 years of age comprise one-quarter of India's rapidly growing population. In spite of India's reputation for respecting women, to an extent to treat her as a goddess, the moment a baby is born, the first thing comes to mind is "boy or girl?" as the differences are beyond just being biological. This article examines the significance of various psychological constructs and psychosocial issues that are important in the life of a "girl" baby born in our country.

Contemporary habitat discontinuity and historic glacial ice drive genetic divergence in Chilean kelp

PubMed Central

2010-01-01

Background South America's western coastline, extending in a near-straight line across some 35 latitudinal degrees, presents an elegant setting for assessing both contemporary and historic influences on cladogenesis in the marine environment. Southern bull-kelp (Durvillaea antarctica) has a broad distribution along much of the Chilean coast. This species represents an ideal model taxon for studies of coastal marine connectivity and of palaeoclimatic effects, as it grows only on exposed rocky coasts and is absent from beaches and ice-affected shores. We expected that, along the central Chilean coast, D. antarctica would show considerable phylogeographic structure as a consequence of the isolating effects of distance and habitat discontinuities. In contrast, we hypothesised that further south - throughout the region affected by the Patagonian Ice Sheet at the Last Glacial Maximum (LGM) - D. antarctica would show relatively little genetic structure, reflecting postglacial recolonisation. Results Mitochondrial (COI) and chloroplast (rbcL) DNA analyses of D. antarctica from 24 Chilean localities (164 individuals) revealed two deeply divergent (4.5 - 6.1% for COI, 1.4% for rbcL) clades from the centre and south of the country, with contrasting levels and patterns of genetic structure. Among populations from central Chile (32° - 44°S), substantial phylogeographic structure was evident across small spatial scales, and a significant isolation-by-distance effect was observed. Genetic disjunctions in this region appear to correspond to the presence of long beaches. In contrast to the genetic structure found among central Chilean populations, samples from the southern Chilean Patagonian region (49° - 56°S) were genetically homogeneous and identical to a haplotype recently found throughout the subantarctic region. Conclusions Southern (Patagonian) Chile has been recolonised by D. antarctica relatively recently, probably since the LGM. The inferred trans-oceanic ancestry of these Patagonian populations supports the notion that D. antarctica is capable of long-distance dispersal via rafting. In contrast, further north in central Chile, the correspondence of genetic disjunctions in D. antarctica with long beaches indicates that habitat discontinuity drives genetic isolation among established kelp populations. We conclude that rafting facilitates colonisation of unoccupied shores, but has limited potential to enhance gene-flow among established populations. Broadly, this study demonstrates that some taxa may be considered to have either high or low dispersal potential across different temporal and geographic scales. PMID:20594354

Perspectives on population growth.

PubMed

1996-09-01

Assume that everyone has the same information on population growth. There are many different opinions on what that information means and what should be done about it. Some people worry about current rates of growth, especially in the context of growing per capita consumption, and believe that all reasonable steps should be taken to reduce rates and stabilize population size. Others believe that growing populations can be accommodated by reducing consumption in rich countries, that technological progress will supply the new resources needed, that the development needed to support a larger population can be sustained, that large population size fosters prosperity, or that birth rates are falling and current growth is just temporary. These are all valid positions worthy of at least debate. Interest groups commonly acknowledgement population growth as a significant issue, but offer no response to it. Sometimes the issue goes unrecognized because it conflicts with a more highly valued personal agenda item. Finally, some responses come from confusion and anger rather than reasoning or self-interest. The proponents of these latter arguments bring nothing constructive to the debate.

Reflectance and internal structure of leaves from several crops during a growing season.

NASA Technical Reports Server (NTRS)

Sinclair, T. R.; Hoffer, R. M.; Schreiber, M. M.

1971-01-01

Measurements of spectral reflectance characteristics during a growing season of leaves from six crops are reported. These crops include soybeans, wheat, oats, sorghum, corn, and sudangrass. The characteristics measured are related to changes in leaf structure and water content.

Modelling the structural response of cotton plants to mepiquat chloride and population density

PubMed Central

Gu, Shenghao; Evers, Jochem B.; Zhang, Lizhen; Mao, Lili; Zhang, Siping; Zhao, Xinhua; Liu, Shaodong; van der Werf, Wopke; Li, Zhaohu

2014-01-01

Background and Aims Cotton (Gossypium hirsutum) has indeterminate growth. The growth regulator mepiquat chloride (MC) is used worldwide to restrict vegetative growth and promote boll formation and yield. The effects of MC are modulated by complex interactions with growing conditions (nutrients, weather) and plant population density, and as a result the effects on plant form are not fully understood and are difficult to predict. The use of MC is thus hard to optimize. Methods To explore crop responses to plant density and MC, a functional–structural plant model (FSPM) for cotton (named CottonXL) was designed. The model was calibrated using 1 year's field data, and validated by using two additional years of detailed experimental data on the effects of MC and plant density in stands of pure cotton and in intercrops of cotton with wheat. CottonXL simulates development of leaf and fruits (square, flower and boll), plant height and branching. Crop development is driven by thermal time, population density, MC application, and topping of the main stem and branches. Key Results Validation of the model showed good correspondence between simulated and observed values for leaf area index with an overall root-mean-square error of 0·50 m2 m−2, and with an overall prediction error of less than 10 % for number of bolls, plant height, number of fruit branches and number of phytomers. Canopy structure became more compact with the decrease of leaf area index and internode length due to the application of MC. Moreover, MC did not have a substantial effect on boll density but increased lint yield at higher densities. Conclusions The model satisfactorily represents the effects of agronomic measures on cotton plant structure. It can be used to identify optimal agronomic management of cotton to achieve optimal plant structure for maximum yield under varying environmental conditions. PMID:24489020

Structural Insight Into the Role of Mutual Polymorphism and Conservatism in the Contact Zone of the NFR5-K1 Heterodimer With the Nod Factor.

PubMed

Igolkina, A A; Porozov, Yu B; Chizhevskaya, E P; Andronov, E E

2018-01-01

Sandwich-like docking configurations of the heterodimeric complex of NFR5 and K1 Vicia sativa receptor-like kinases together with the putative ligand, Nod factor (NF) of Rhizobium leguminosarum bv. viciae , were modeled and two of the most probable configurations were assessed through the analysis of the mutual polymorphisms and conservatism. We carried out this analysis based on the hypothesis that in a contact zone of two docked components (proteins or ligands) the population polymorphism or conservatism is mutual, i.e., the variation in one component has a reflected variation in the other component. The population material of 30 wild-growing V. sativa (leaf pieces) was collected from a large field (uncultivated for the past 25-years) and pooled; form this pool, 100 randomly selected cloned fragments of NFR5 gene and 100 of K1 gene were sequenced by the Sanger method. Congruence between population trees of NFR5 and K1 haplotypes allowed us to select two respective haplotypes, build their 3D structures, and perform protein-protein docking. In a separate simulation, the protein-ligand docking between NFR5 and NF was carried out. We merged the results of the two docking experiments and extracted NFR5-NF-K1 complexes, in which NF was located within the cavity between two receptors. Molecular dynamics simulations indicated two out of six complexes as stable. Regions of mutual polymorphism in the contact zone of one complex overlapped with known NF structural variations produced by R. leguminosarum bv. viciae . A total of 74% of the contact zone of another complex contained mutually polymorphic and conservative areas. Common traits of the obtained two stable structures allowed us to hypothesize the functional role of three-domain structure of plant LysM-RLKs in their heteromers.

Lake sturgeon population characteristics in Rainy Lake, Minnesota and Ontario

USGS Publications Warehouse

Adams, W.E.; Kallemeyn, L.W.; Willis, D.W.

2006-01-01

Rainy Lake contains a native population of lake sturgeon Acipenser fulvescens that has been largely unstudied. The aims of this study were to document the population characteristics of lake sturgeon in Rainy Lake and to relate environmental factors to year-class strength for this population. Gill-netting efforts throughout the study resulted in the capture of 322 lake sturgeon, including 50 recaptures. Lake sturgeon in Rainy Lake was relatively plump and fast growing compared with a 32-population summary. Population samples were dominated by lake sturgeon between 110 and 150 cm total length. Age–structure analysis of the samples indicated few younger (<10 years) lake sturgeon, but the smallest gill net mesh size used for sampling was 102 mm (bar measure) and would not retain small sturgeon. Few lake sturgeon older than age 50 years were captured, and maximum age of sampled fish was 59 years. Few correlations existed between lake sturgeon year-class indices and both annual and monthly climate variables, except that mean June air temperature was positively correlated with year-class strength. Analysis of Rainy Lake water elevation and resulting lake sturgeon year-class strength indices across years yielded consistent but weak negative correlations between late April and early June, when spawning of lake sturgeon occurs. The baseline data collected in this study should allow Rainy Lake biologists to establish more specific research questions in the future.

Implications of an ageing population in the Asian context.

PubMed

Suyono, H

1999-12-01

Population aging is the increasing number and proportion of old persons aged 60 years and above in the developing countries and 65 years and above in the developed countries that exceeds 10% of the total population. In Asia, the last decade of the 20th century is marked by significant changes in the age structure due to the process of population aging. The implications of this aging population on the life of Asian countries has to be addressed since demographically the current situation is changing rapidly and there lie the future challenges that have to be answered. Due to the growing size of the elderly population, Asia will need better plans to prevent these elderly groups from turning into the socioeconomically vulnerable group of society. However, many governments are not prepared with effective policies, programs, and services that are particularly designed to care for the elderly. The provision of infrastructure and services, including education, employment, health and housing are necessary steps that need to be taken. Some of the suggested measures include: the Social Safety Net Programs; the implementation of the Association of Southeast Asian Nations Plan of Action on Rural Development and Poverty Eradication; and strengthen volunteerism and the role of private sector in human development. The role of the media in transmitting information concerning policies and programs intended to increase the welfare of the older persons is also very important.

A preliminary assessment of mouflon abundance at the Kahuku Unit of Hawaii Volcanoes National Park

USGS Publications Warehouse

Hess, Steven C.; Kawakami, Ben; Okita, David; Medeiros, Keola

2006-01-01

Hawaii Volcanoes National Park (HAVO) recently acquired the 115,653 acre Kahuku Ranch unit adjacent to the existing Mauna Loa section of HAVO. Kahuku contains numerous exceptional natural resources including many federally listed threatened and endangered species. An apparently large and growing population of alien mouflon sheep (Ovis gmelini musimon), however, threatens sensitive native plants and forest bird habitats. Population composition and abundance estimates were urgently needed to determine the magnitude of resources required to manage this species and justify costs. We surveyed 32,433 acres from helicopter over 2 days in November 2004 during breeding to determine the abundance and population structure. We estimated that there were more than 2,586 ? 705 (90% CI) mouflon at Kahuku. Overall, group sizes averaged 7.8 and the sex ratio was 1:2.4 rams:ewes, but approximately 44% of the population was concentrated in forested areas near ranching operations where group sizes averaged >15 and the sex ratio was 1:3.9 rams:ewes. The remaining 56% of the population occurred widely dispersed in subalpine shrubland and barren lava flows. Abundance estimates are likely to be conservative because they were not adjusted for detection probability. Ground-based surveys of lambs suggest upper biological limit to annual population increase of 33.1% under existing environmental conditions. Historical information used to calculate population trends indicated the apparent rate of population increase to be 21.1%. In the absence of removals, the population increment for 2004-2005, would be more than 546-856, and the population doubling time with these growth rates is 3-4 years.

Forest structure, stand composition, and climate-growth response in montane forests of Jiuzhaigou National Nature Reserve, China.

PubMed

Schwartz, Mark W; Dolanc, Christopher R; Gao, Hui; Strauss, Sharon Y; Schwartz, Ari C; Williams, John N; Tang, Ya

2013-01-01

Montane forests of western China provide an opportunity to establish baseline studies for climate change. The region is being impacted by climate change, air pollution, and significant human impacts from tourism. We analyzed forest stand structure and climate-growth relationships from Jiuzhaigou National Nature Reserve in northwestern Sichuan province, along the eastern edge of the Tibetan plateau. We conducted a survey to characterize forest stand diversity and structure in plots occurring between 2050 and 3350 m in elevation. We also evaluated seedling and sapling recruitment and tree-ring data from four conifer species to assess: 1) whether the forest appears in transition toward increased hardwood composition; 2) if conifers appear stressed by recent climate change relative to hardwoods; and 3) how growth of four dominant species responds to recent climate. Our study is complicated by clear evidence of 20(th) century timber extraction. Focusing on regions lacking evidence of logging, we found a diverse suite of conifers (Pinus, Abies, Juniperus, Picea, and Larix) strongly dominate the forest overstory. We found population size structures for most conifer tree species to be consistent with self-replacement and not providing evidence of shifting composition toward hardwoods. Climate-growth analyses indicate increased growth with cool temperatures in summer and fall. Warmer temperatures during the growing season could negatively impact conifer growth, indicating possible seasonal climate water deficit as a constraint on growth. In contrast, however, we found little relationship to seasonal precipitation. Projected warming does not yet have a discernible signal on trends in tree growth rates, but slower growth with warmer growing season climates suggests reduced potential future forest growth.

Forest Structure, Stand Composition, and Climate-Growth Response in Montane Forests of Jiuzhaigou National Nature Reserve, China

PubMed Central

Schwartz, Mark W.; Dolanc, Christopher R.; Gao, Hui; Strauss, Sharon Y.; Schwartz, Ari C.; Williams, John N.; Tang, Ya

2013-01-01

Montane forests of western China provide an opportunity to establish baseline studies for climate change. The region is being impacted by climate change, air pollution, and significant human impacts from tourism. We analyzed forest stand structure and climate-growth relationships from Jiuzhaigou National Nature Reserve in northwestern Sichuan province, along the eastern edge of the Tibetan plateau. We conducted a survey to characterize forest stand diversity and structure in plots occurring between 2050 and 3350 m in elevation. We also evaluated seedling and sapling recruitment and tree-ring data from four conifer species to assess: 1) whether the forest appears in transition toward increased hardwood composition; 2) if conifers appear stressed by recent climate change relative to hardwoods; and 3) how growth of four dominant species responds to recent climate. Our study is complicated by clear evidence of 20th century timber extraction. Focusing on regions lacking evidence of logging, we found a diverse suite of conifers (Pinus, Abies, Juniperus, Picea, and Larix) strongly dominate the forest overstory. We found population size structures for most conifer tree species to be consistent with self-replacement and not providing evidence of shifting composition toward hardwoods. Climate-growth analyses indicate increased growth with cool temperatures in summer and fall. Warmer temperatures during the growing season could negatively impact conifer growth, indicating possible seasonal climate water deficit as a constraint on growth. In contrast, however, we found little relationship to seasonal precipitation. Projected warming does not yet have a discernible signal on trends in tree growth rates, but slower growth with warmer growing season climates suggests reduced potential future forest growth. PMID:23951188

Modeling the relationship between wolf control and cattle depredation

PubMed Central

2017-01-01

Wolf control to reduce cattle depredation is an important issue to ecology and agriculture in the United States. Two recent papers use the same dataset having wolf population characteristics and cattle depredation, but come to opposing conclusions concerning the link between wolf control and cattle depredation. Our paper aims to resolve this issue by using the same dataset and developing a model based on a causal association that would explain the nature of the relationship between wolf control and cattle depredation. We use the data on wolf population, number of cattle, number of wolves killed and number of cattle killed, from the U.S. Fish and Wildlife Services Interagency Annual Wolf Reports over the period of 1987–2012. We find a positive link between wolf control and cattle depredation. However, it would be incorrect to infer that wolf control has a positive effect on the number of cattle depredated. We maintain that this link comes from a growing wolf population, which increases cattle depredation, and in turn, causes an increase in the number of wolves killed. While the wolf population is growing, we see both wolf removal and cattle depredation simultaneously grow. It is not until the wolf population growth nears the steady state, that removal of wolves has a sufficient negative effect to reduce or stabilize the number of cattle depredated. PMID:29084261

The evolution of labile traits in sex- and age-structured populations.

PubMed

Childs, Dylan Z; Sheldon, Ben C; Rees, Mark

2016-03-01

Many quantitative traits are labile (e.g. somatic growth rate, reproductive timing and investment), varying over the life cycle as a result of behavioural adaptation, developmental processes and plastic responses to the environment. At the population level, selection can alter the distribution of such traits across age classes and among generations. Despite a growing body of theoretical research exploring the evolutionary dynamics of labile traits, a data-driven framework for incorporating such traits into demographic models has not yet been developed. Integral projection models (IPMs) are increasingly being used to understand the interplay between changes in labile characters, life histories and population dynamics. One limitation of the IPM approach is that it relies on phenotypic associations between parents and offspring traits to capture inheritance. However, it is well-established that many different processes may drive these associations, and currently, no clear consensus has emerged on how to model micro-evolutionary dynamics in an IPM framework. We show how to embed quantitative genetic models of inheritance of labile traits into age-structured, two-sex models that resemble standard IPMs. Commonly used statistical tools such as GLMs and their mixed model counterparts can then be used for model parameterization. We illustrate the methodology through development of a simple model of egg-laying date evolution, parameterized using data from a population of Great tits (Parus major). We demonstrate how our framework can be used to project the joint dynamics of species' traits and population density. We then develop a simple extension of the age-structured Price equation (ASPE) for two-sex populations, and apply this to examine the age-specific contributions of different processes to change in the mean phenotype and breeding value. The data-driven framework we outline here has the potential to facilitate greater insight into the nature of selection and its consequences in settings where focal traits vary over the lifetime through ontogeny, behavioural adaptation and phenotypic plasticity, as well as providing a potential bridge between theoretical and empirical studies of labile trait variation. © 2016 The Authors Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

Hispanics: A Diverse Population of Students to Influence the Landscape of Higher Education

ERIC Educational Resources Information Center

Page, Jill

2013-01-01

Hispanic students are a growing and pervasive population within higher education. This position paper examines population characteristics and educational patterns of Hispanic students that underscore failures of the higher education system in serving these students, in addition to institutional issues and cultural values that further complicate…

Population.

ERIC Educational Resources Information Center

International Planned Parenthood Federation, London (England).

In an effort to help meet the growing interest and concern about the problems created by the rapid growth of population, The International Planned Parenthood Federation has prepared this booklet with the aim of assisting the study of the history and future trends of population growth and its impact on individual and family welfare, national,…

How GNSS Enables Precision Farming

DOT National Transportation Integrated Search

2014-12-01

Precision farming: Feeding a Growing Population Enables Those Who Feed the World. Immediate and Ongoing Needs - population growth (more to feed) - urbanization (decrease in arable land) Double food production by 2050 to meet world demand. To meet thi...

Microbial mutualism at a distance: The role of geometry in diffusive exchanges

NASA Astrophysics Data System (ADS)

Peaudecerf, François J.; Bunbury, Freddy; Bhardwaj, Vaibhav; Bees, Martin A.; Smith, Alison G.; Goldstein, Raymond E.; Croze, Ottavio A.

2018-02-01

The exchange of diffusive metabolites is known to control the spatial patterns formed by microbial populations, as revealed by recent studies in the laboratory. However, the matrices used, such as agarose pads, lack the structured geometry of many natural microbial habitats, including in the soil or on the surfaces of plants or animals. Here we address the important question of how such geometry may control diffusive exchanges and microbial interaction. We model mathematically mutualistic interactions within a minimal unit of structure: two growing reservoirs linked by a diffusive channel through which metabolites are exchanged. The model is applied to study a synthetic mutualism, experimentally parametrized on a model algal-bacterial co-culture. Analytical and numerical solutions of the model predict conditions for the successful establishment of remote mutualisms, and how this depends, often counterintuitively, on diffusion geometry. We connect our findings to understanding complex behavior in synthetic and naturally occurring microbial communities.

Traditional healing practices among American Muslims: perceptions of community leaders in southeast Michigan.

PubMed

Alrawi, Sara; Fetters, Michael D; Killawi, Amal; Hammad, Adnan; Padela, Aasim

2012-06-01

Despite growing numbers of American Muslims, little empirical work exists on their use of traditional healing practices. We explored the types of traditional healing practices used by American Muslims in southeast Michigan. Twelve semi-structured interviews with American Muslim community leaders identified through a community-academic steering committee were conducted. Using a framework coding structure, a multidisciplinary investigative team identified themes describing traditional healing practices. Traditional healing practices can be categorized into three domains: Islamic religious text based practices, Islamic worship practices, and folk healing practices. Each domain may further contain therapies such as spiritual healing, medicinal herbs, mind body therapy, and dietary prescriptions. Traditional healing practices are utilized in three capacities of care: primary, secondary, and integrative. Our findings demonstrate that American Muslims actively utilize traditional healing practices. Healthcare practitioners caring for this population should be aware of the potential influence of these practices on health behaviors.

Experimental Study on the Flexural Performance of Parallel Strand Bamboo Beams

PubMed Central

Zhou, Aiping; Bian, Yuling

2014-01-01

Searching for materials to provide proper housing with less emission and low energy becomes an urgent demand with the ever-growing population. Bamboo has gained a reputation as an ecofriendly, highly renewable source of material. Parallel Strand Bamboo (PSB) is a new biocomposite made of bamboo strips which has superiority performances than wood products. It has attracted considerable interests as a sustainable alternative for more traditional building materials. But the mechanical performance study of PSB as construction materials is still inadequate. Also, the structural behavior of PSB is not quite understood as conventional construction materials, which results in the difficulties to predict the performances of PSB structural members. To achieve this purpose, 4-point bending experiments for PSB beams were carried out. The flexural performances, mode of failure in bending, and the damage mechanism of PSB beams were investigated in this paper. PMID:24701141

A High-Performance Cellular Automaton Model of Tumor Growth with Dynamically Growing Domains

PubMed Central

Poleszczuk, Jan; Enderling, Heiko

2014-01-01

Tumor growth from a single transformed cancer cell up to a clinically apparent mass spans many spatial and temporal orders of magnitude. Implementation of cellular automata simulations of such tumor growth can be straightforward but computing performance often counterbalances simplicity. Computationally convenient simulation times can be achieved by choosing appropriate data structures, memory and cell handling as well as domain setup. We propose a cellular automaton model of tumor growth with a domain that expands dynamically as the tumor population increases. We discuss memory access, data structures and implementation techniques that yield high-performance multi-scale Monte Carlo simulations of tumor growth. We discuss tumor properties that favor the proposed high-performance design and present simulation results of the tumor growth model. We estimate to which parameters the model is the most sensitive, and show that tumor volume depends on a number of parameters in a non-monotonic manner. PMID:25346862

Successional Development of Sulfate-Reducing Bacterial Populations and Their Activities in a Wastewater Biofilm Growing under Microaerophilic Conditions

PubMed Central

Ito, Tsukasa; Okabe, Satoshi; Satoh, Hisashi; Watanabe, Yoshimasa

2002-01-01

A combination of fluorescence in situ hybridization, microprofiles, denaturing gradient gel electrophoresis of PCR-amplified 16S ribosomal DNA fragments, and 16S rRNA gene cloning analysis was applied to investigate successional development of sulfate-reducing bacteria (SRB) community structure and in situ sulfide production activity within a biofilm growing under microaerophilic conditions (dissolved oxygen concentration in the bulk liquid was in the range of 0 to 100 μM) and in the presence of nitrate. Microelectrode measurements showed that oxygen penetrated 200 μm from the surface during all stages of biofilm development. The first sulfide production of 0.32 μmol of H2S m−2 s−1 was detected below ca. 500 μm in the 3rd week and then gradually increased to 0.70 μmol H2S m−2 s−1 in the 8th week. The most active sulfide production zone moved upward to the oxic-anoxic interface and intensified with time. This result coincided with an increase in SRB populations in the surface layer of the biofilm. The numbers of the probe SRB385- and 660-hybridized SRB populations significantly increased to 7.9 × 109 cells cm−3 and 3.6 × 109 cells cm−3, respectively, in the surface 400 μm during an 8-week cultivation, while those populations were relatively unchanged in the deeper part of the biofilm, probably due to substrate transport limitation. Based on 16S rRNA gene cloning analysis data, clone sequences that related to Desulfomicrobium hypogeium (99% sequence similarity) and Desulfobulbus elongatus (95% sequence similarity) were most frequently found. Different molecular analyses confirmed that Desulfobulbus, Desulfovibrio, and Desulfomicrobium were found to be the numerically important members of SRB in this wastewater biofilm. PMID:11872492

Healthy Marriage Programs: Learning What Works

ERIC Educational Resources Information Center

Dion, M. Robin

2005-01-01

Evidence of public and private interest in programs designed to strengthen the institution of marriage and reduce the number of children growing up without both their parents is growing. Robin Dion addresses the question of whether such programs can be effective, especially among disadvantaged populations. She begins by describing a variety of…

The Recruitment and Selection of Principals Who Increase Student Learning

ERIC Educational Resources Information Center

Ash, Ruth C.; Hodge, Patricia H.; Connell, Peggy H.

2013-01-01

The overall picture that emerges from a review of literature pinpoints two elements that inhibit recruiting and hiring effective principals. Primary hindrances include the growing shortage of qualified applicants in conjunction with a growing student population and the reality of the challenging demands, responsibilities, and complexities of the…

The Solutionaries Education for a Better World: What Is Schooling for?

ERIC Educational Resources Information Center

Weil, Zoe

2012-01-01

People are confronted with escalating, interrelated global problems: climate change, growing extinction rates, economic instability, a looming energy catastrophe, depletion of resources, and an ever-growing population of people, each of whom requires food, water, shelter, and a job. Clearly, people need to create better, sustainable, and…

Issues in Curriculum and Instruction for Culturally and Linguistically Diverse Students

ERIC Educational Resources Information Center

Hogan, Kathleen; Hathcote, Andrea

2014-01-01

Teachers are being asked to educate a variety of students, including a growing number of students from culturally and linguistically diverse (CLD) backgrounds (Diaz-Rico, 2012. "A course for teaching English learners." Upper Saddle River, NY: Pearson). Because students from diverse backgrounds are the fastest growing population in…

The gut immune system: A new frontier in gut health research

USDA-ARS?s Scientific Manuscript database

As the world population grows and developing countries become more affluent, the global consumption of meat will increase by more than 50% within the next 10 years. Confronting the increasing demand for poultry food products are emerging field diseases, increasing regulatory ban of antibiotics grow...

Producing biofuel crops: environmental and economic implications and strategies

USDA-ARS?s Scientific Manuscript database

The growing need for sustainable fuel sources must become compatible with the continued need for food by an ever increasing world population and the effects of climate change on ability to produce food and biofuel. Growing more hectares of biofuel crops such as corn increases sediment and nutrient l...

Variances in nutrient content and yield of alfalfa protein concentrate processed with five methods

USDA-ARS?s Scientific Manuscript database

The demand for protein is growing with increased populations and world affluence. A sustainable and affordable protein source is needed to support the growing aquaculture industry worldwide. Alfalfa produces high levels of protein and provides numerous environmental services, potentially making it a...

Temporal and spatial variation in alkaloid levels in Achnatherum robustum, a native grass infected with the endophyte Neotyphodium.

PubMed

Faeth, Stanley H; Gardner, Dale R; Hayes, Cinnamon J; Jani, Andrea; Wittlinger, Sally K; Jones, Thomas A

2006-02-01

The native North American perennial grass Achnatherum robustum (Vasey) Barkworth [= Stipa robusta (Vasey) Scribn.] or sleepygrass is toxic and narcotic to livestock. The causative agents are alkaloidal mycotoxins produced from infections by a systemic and asexual Neotyphodium endophyte. Recent studies suggest that toxicity is limited across the range of sleepygrass in the Southwest USA. We sampled 17 populations of sleepygrass with varying distance from one focal population known for its high toxicity levels near Cloudcroft, NM, USA. For some, we sampled individual plants twice within the same growing season and over successive years (2001-2004). We also determined infection levels in each population. In general, all populations were highly infected, but infection levels were more variable near the focal population. Only infected plants within populations near the Cloudcroft area produced alkaloids. The ergot alkaloid, ergonovine, comprised the bulk of the alkaloids, with lesser amounts of lysergic and isolysergic acid amides and ergonovinine alkaloids. Levels of all alkaloids were positively correlated among individual plants within and between growing seasons. Infected plants that produced no alkaloids in 1 yr did not produce any alkaloids within the same growing season or in other years. Levels of alkaloids in sleepygrass populations declined with distance from the Cloudcroft population, although infection levels increased. Infected plants in populations in northern New Mexico and southern Colorado produced no alkaloids at all despite 100% infectivity. Our results suggest that only specific Neotyphodium haplotypes or specific Neotyphodium-grass combinations produce ergot alkaloids in sleepygrass. The Neotyphodium haplotype or host-endophyte combination that produces toxic levels of alkaloids appears restricted to one locality across the range of sleepygrass. Because of the wide variation in alkaloid levels among populations, interactions between the endophyte and host, and consequences for herbivores, competitors, and pathogens and other components of the community, are likely to vary widely across the geographic range of this native grass.

Can human populations be stabilized?

NASA Astrophysics Data System (ADS)

Warren, Stephen G.

2015-02-01

Historical examples of demographic change, in China, Italy, Nigeria, Utah, Easter Island, and elsewhere, together with simple mathematics and biological principles, show that stabilizing world population before it is limited by food supply will be more difficult than is generally appreciated. United Nations population projections are wrong because they assume, in spite of the absence of necessary feedbacks, that all nations will converge rapidly to replacement-level fertility and thereafter remain at that level. Education of women and provision of contraceptives have caused dramatic reductions in fertility, but many groups, including some that are well-educated, maintain high fertility. Small groups with persistent high fertility can grow to supplant low-fertility groups, resulting in continued growth of the total population. The global average fertility rate could rise even if each country's fertility rate is falling. In some low-fertility European countries where deaths exceed births, the population continues to grow because of immigration. Producing more than two offspring is normal for all animal species with stable populations because their populations are limited by resources or predation rather than birth control. It may therefore be appropriate to view the growth of human population as the result not of excess fertility but rather of excess food.

[Population and development].

PubMed

Castanon Romo, R; Sandoval Navarrete, J

1996-01-01

This broad survey of the debate concerning the relationship between population growth and economic development discusses the history and current status of world population growth, summarizes several influential theoretical positions on the topic, and proposes that redefinition of women's social role is indispensable if worldwide control of population growth is to be achieved. The introductory section discusses the acceleration of population growth in the second half of the 20th century and the increasing concentration of growth in the poor and developing countries. The positions of those who see in population control a means of promoting economic development and political stability are contrasted to the positions of those who believe that a large and growing population is the key to achieving economic and political progress. The international community, facing great uncertainty about the size, distribution, and well-being of the future world population, is increasingly concerned about the effect of growing numbers on the environment and natural resources. The second section summarizes the works of Malthus, Julian Simon, and the Club of Rome, and analyzes the propositions of demographic transition theory. The conclusion notes that despite uncertainty about the future of world population, development, and health, most of the poorest countries have become aware of the desirability of slowing population growth. A broad redefinition of the social role of women will inevitably accompany the worldwide demographic transition.

[Population and crisis. Economic inflexibility or demographic subordination].

PubMed

Morelos, J B

1989-01-01

Much speculation, fact-based and subjective, has centered on the links between population and economic crisis, and between population and progress. In the past, famines directly affected the size and dynamics of population in affected regions, and such cycles inspired theories that regarded subsistence as the adjustment mechanism for demographic regimes. Population has alternatively been viewed as a crucial factor of production and a force for modernization and progress. After World War I and the Great Depression, many economists believed that population growth would be indispensable for renewing economic expansion. The favorable view of population growth in Mexico led to measures to repatriate emigrants, attract immigrants, and improve health conditions. The gross national product grew by around 6.0% annually on average between 1940 and 1960, and the per capita GNP by about 3%. Demographic dynamics acquired momentum by the 1960s, with high growth rates, a young age structure, considerable demographic inertia, and relative predominance of the urban population. Indications began to appear that a primarily economic solution to achieving full development would be unlikely. The polarization of development, distributive insufficiency, distortions in exchange relations for agricultural products, and incorporation of inappropriate technologies were factors decreasing the ability of the economy to respond adequately to population demands. National development was insufficient to meet growing demographic pressures in the labor market, educational system, housing, and urban services. The adjustment programs reduced even further the flexibility of the government to respond to pressures. Expectations for the future have been seriously compromised by the fall of real incomes.

Population clustering and clonal structure evidence the relict state of Ulmus minor Mill. in the Balearic Islands

PubMed Central

Fuentes-Utrilla, P; Valbuena-Carabaña, M; Ennos, R; Gil, L

2014-01-01

Field elm (Ulmus minor) is a riparian tree that grows in rare, small populations scattered along temporary watercourses in the Balearic Islands, nowadays mostly covered with Mediterranean vegetation. Agriculture and farming on the fertile land along the periodically flooded plains have reduced the elm populations to sparse tree lines along the creek beds. The presence of field elm in this very anthropic landscape has led some authors to consider it as an introduced species in the Balearics. However, pollen data suggest these elms may be the remains of larger populations experiencing continuous population shrinkage during the Holocene, and hence be native to the isles. In this paper, we apply genetic markers to assess whether field elm is or is not indigenous to the Balearic Islands. We compare the genetic variation in nine nuclear microsatellites of six Balearic populations (three in each of the largest islands, Majorca and Minorca) with that of three natural Iberian populations located in two regions, one geologically (Baetic mountains, SE Iberia) and another historically (Catalonia, NE Iberia) related to the islands. Principal coordinates analysis and Bayesian clustering methods reveal a strong genetic differentiation of the Balearic populations from the Iberian ones, and even among islands, which support their native origin. Genotypic variation in the islands is very low and clonal reproduction is very high compared with the mainland, as it is frequently observed in populations of clonal species where sexual reproduction is limited. We discuss the practical implications of these findings for the conservation of elm genetic resources of these findings. PMID:24619184

Drought responses of conifers in ecotone forests of northern Arizona: tree ring growth and leaf delta13C.

PubMed

Adams, Henry D; Kolb, Thomas E

2004-07-01

We sought to understand differences in tree response to meteorological drought among species and soil types at two ecotone forests in northern Arizona, the pinyon-juniper woodland/ponderosa pine ecotone, and the higher elevation, wetter, ponderosa pine/mixed conifer ecotone. We used two approaches that provide different information about drought response: the ratio of standardized radial growth in wet years to dry years (W:D) for the period between years 1950 and 2000 as a measure of growth response to drought, and delta13C in leaves formed in non-drought (2001) and drought (2002) years as a measure of change in water use efficiency (WUE) in response to drought. W:D and leaf delta13C response to drought for Pinus edulis and P. ponderosa did not differ for trees growing on coarse-texture soils derived from cinders compared with finer textured soils derived from flow basalts or sedimentary rocks. P. ponderosa growing near its low elevation range limit at the pinyon-juniper woodland/ponderosa pine ecotone had a greater growth response to drought (higher W:D) and a larger increase in WUE in response to drought than co-occurring P. edulis growing near its high elevation range limit. P. flexilis and Pseudotsuga menziesii growing near their low elevation range limit at the ponderosa pine/mixed conifer ecotone had a larger growth response to drought than co-occurring P. ponderosa growing near its high elevation range limit. Increases in WUE in response to drought were similar for all species at the ponderosa pine/mixed conifer ecotone. Low elevation populations of P. ponderosa had greater growth response to drought than high-elevation populations, whereas populations had a similar increase in WUE in response to drought. Our findings of different responses to drought among co-occurring tree species and between low- and high-elevation populations are interpreted in the context of drought impacts on montane coniferous forests of the southwestern USA.

[Demographic variables, inevitable passage. Irrigated areas and health of populations].

PubMed

Ouedraogo, D

1992-06-01

The Kou Valley rice production area is the largest irrigated expanse in use by peasants in Burkina Faso. 1260 hectares of rice paddy provide two harvests each year for one thousand families, who are mostly in-migrants. The Kou Valley rice paddy was brought into production between 1970 and 1974 to reduce crowding in the overpopulated Mossi plateau, control emigration, increase national rice production, and improve living conditions. A research project in the area is intended to clarify relations between development policies and demographic trends, health conditions, and economic and social welfare of the population. A study compared the rice growing families with 1255 non-rice growing natives of the area and 4763 non-rice growing spontaneous in-migrants. The rice growers enjoyed an impressive increase in incomes, but their infant mortality rates did not decline as greatly as expected and were slightly higher than those of the spontaneous in-migrants. Contaminated water, malaria, schistosomiasis, and the lack of health infrastructure and education were probably factors in the high infant mortality. The incidence of child malnutrition was also greater among the rice growers than among the spontaneous migrants. Women in rice growing families work in the paddies all year. They no longer have access to their own lands and they have less time for child care. The improved economic conditions of the rice growers have not been accompanied by improved living conditions for their families. Women of rice growing families have an average of 6.8 children at age 50, compared to 6.1 among spontaneous in-migrants and 3.1 in the native population. Average household size fluctuated among the rice growers as families sought to add workers to maximize production and later to shed members in response to population pressure and reduced per capita income. The project experience suggests that greater thought should be given to the predictable demographic evolution of households and to the health consequence of development projects.

Cultural and social determinants of health among indigenous Mexican migrants in the United States.

PubMed

Lee, Junghee; Donlan, William; Cardoso, Edgar Ezequiel Orea; Paz, Juan Jesus

2013-01-01

Despite growing numbers, indigenous Mexican migrants are relatively invisible to health practitioners who group them with nonindigenous, mestizo Mexican-origin populations. Associations between indigenous and mestizo cultural identifications with psychosocial characteristics and health indicators among indigenous Mexican migrants were examined. Results revealed gender differences in cultural identifications, perceived discrimination, self-esteem, self-efficacy, and various health indicators including depression severity, culture-bound syndromes, and self-rated health. Multivariate regression and structural equation path modeling demonstrated how indigenous cultural identification and perceived discrimination affects health. Findings suggest that interventions should utilize indigenous community-based activities designed to promote self-esteem and the value of indigenous culture, with a focus on females.

The complete mitochondrial genome of the sandbar shark Carcharhinus plumbeus.

PubMed

Blower, Dean C; Ovenden, Jennifer R

2016-01-01

The sandbar shark, Carcharhinus plumbeus, a major representative species in shark fisheries worldwide is now considered vulnerable to overfishing. A pool of 774,234 Roche 454 shotgun sequences from one individual were assembled into a 16,706 bp mitogenome with 33× average coverage depth. It comprised 13 protein coding genes, 22 transfer RNA's, 2 ribosomal genes and 2 non-coding regions, typical of a vertebrate mitogenome. As expected for sharks, an A-T nucleotide bias was evident. This adds to rapidly growing number of mitogenome assemblies for the economically important Carcharhinidae family. The C. plumbeus mitogenome will assist researchers, fisheries and conservation managers interested in shark molecular systematics, phylogeography, conservation genetics, population and stock structure.

The Association between Non-Alcoholic Fatty Liver Disease and Cardiovascular Risk in Children.

PubMed

Di Sessa, Anna; Umano, Giuseppina Rosaria; Miraglia Del Giudice, Emanuele

2017-07-07

The rising prevalence of childhood obesity in the past decades has made Non-Alcoholic Fatty Liver Disease (NAFLD) the most common cause of pediatric chronic liver disease worldwide. Currently, a growing body of evidence links NAFLD with cardiovascular disease (CVD) even at an early age. Data on the pediatric population have shown that NAFLD could represent an independent risk factor not only for cardiovascular events but also for early subclinical abnormalities in myocardial structure and function. Briefly, we review the current knowledge regarding the relationship between pediatric NAFLD and cardiovascular risk in an attempt to clarify our understanding of NAFLD as a possible cardiovascular risk factor in childhood.

Saccharomyces cerevisiae biofilm tolerance towards systemic antifungals depends on growth phase.

PubMed

Bojsen, Rasmus; Regenberg, Birgitte; Folkesson, Anders

2014-12-04

Biofilm-forming Candida species cause infections that can be difficult to eradicate, possibly because of antifungal drug tolerance mechanisms specific to biofilms. In spite of decades of research, the connection between biofilm and drug tolerance is not fully understood. We used Saccharomyces cerevisiae as a model for drug susceptibility of yeast biofilms. Confocal laser scanning microscopy showed that S. cerevisiae and C. glabrata form similarly structured biofilms and that the viable cell numbers were significantly reduced by treatment of mature biofilms with amphotericin B but not voriconazole, flucytosine, or caspofungin. We showed that metabolic activity in yeast biofilm cells decreased with time, as visualized by FUN-1 staining, and mature, 48-hour biofilms contained cells with slow metabolism and limited growth. Time-kill studies showed that in exponentially growing planktonic cells, voriconazole had limited antifungal activity, flucytosine was fungistatic, caspofungin and amphotericin B were fungicidal. In growth-arrested cells, only amphotericin B had antifungal activity. Confocal microscopy and colony count viability assays revealed that the response of growing biofilms to antifungal drugs was similar to the response of exponentially growing planktonic cells. The response in mature biofilm was similar to that of non-growing planktonic cells. These results confirmed the importance of growth phase on drug efficacy. We showed that in vitro susceptibility to antifungal drugs was independent of biofilm or planktonic growth mode. Instead, drug tolerance was a consequence of growth arrest achievable by both planktonic and biofilm populations. Our results suggest that efficient strategies for treatment of yeast biofilm might be developed by targeting of non-dividing cells.

Energy production for environmental issues in Turkey

NASA Astrophysics Data System (ADS)

Yuksel, Ibrahim; Arman, Hasan; Halil Demirel, Ibrahim

2017-11-01

Due to the diversification efforts of energy sources, use of natural gas that was newly introduced into Turkish economy, has been growing rapidly. Turkey has large reserves of coal, particularly of lignite. The proven lignite reserves are 8.0 billion tons. The estimated total possible reserves are 30 billion tons. Turkey, with its young population and growing energy demand per person, its fast growing urbanization, and its economic development, has been one of the fast growing power markets of the world for the last two decades. It is expected that the demand for electric energy in Turkey will be 580 billion kWh by the year 2020. Turkey's electric energy demand is growing about 6-8% yearly due to fast economic growing. This paper deals with energy demand and consumption for environmental issues in Turkey.

Effects of landscape change on fish assemblage structure in a rapidly growing metropolitan area in North Carolina, USA

USGS Publications Warehouse

Kennen, J.G.; Chang, M.; Tracy, B.H.

2005-01-01

We evaluated a comprehensive set of natural and land-use attributes that represent the major facets of urban development at fish monitoring sites in the rapidly growing Raleigh-Durham, North Carolina metropolitan area. We used principal component and correlation analysis to obtain a nonredundant subset of variables that extracted most variation in the complete set. With this subset of variables, we assessed the effect of urban growth on fish assemblage structure. We evaluated variation in fish assemblage structure with nonmetric multidimensional scaling (NMDS). We used correlation analysis to identify the most important environmental and landscape variables associated with significant NMDS axes. The second NMDS axis is related to many indices of land-use/land-cover change and habitat. Significant correlations with proportion of largest forest patch to total patch size (r = -0.460, P < 0.01), diversity of patch types (r = 0.554, P < 0.001), and population density (r = 0.385, P < 0.05) helped identify NMDS axis 2 as a disturbance gradient. Positive and negative correlations between the abundance of redbreast sunfish Lepomis auritus and bluehead chub Nocomis leptocephalus, respectively, and NMDS axis 2 also were evident. The North Carolina index of biotic integrity and many of its component metrics were highly correlated with urbanization. These results indicate that aquatic ecosystem integrity would be optimized by a comprehensive integrated management strategy that includes the preservation of landscape function by maximizing the conservation of contiguous tracts of forested lands and vegetative cover in watersheds. ?? 2005 by the American Fisheries Society.

Buckling instability in ordered bacterial colonies

NASA Astrophysics Data System (ADS)

Boyer, Denis; Mather, William; Mondragón-Palomino, Octavio; Orozco-Fuentes, Sirio; Danino, Tal; Hasty, Jeff; Tsimring, Lev S.

2011-04-01

Bacterial colonies often exhibit complex spatio-temporal organization. This collective behavior is affected by a multitude of factors ranging from the properties of individual cells (shape, motility, membrane structure) to chemotaxis and other means of cell-cell communication. One of the important but often overlooked mechanisms of spatio-temporal organization is direct mechanical contact among cells in dense colonies such as biofilms. While in natural habitats all these different mechanisms and factors act in concert, one can use laboratory cell cultures to study certain mechanisms in isolation. Recent work demonstrated that growth and ensuing expansion flow of rod-like bacteria Escherichia coli in confined environments leads to orientation of cells along the flow direction and thus to ordering of cells. However, the cell orientational ordering remained imperfect. In this paper we study one mechanism responsible for the persistence of disorder in growing cell populations. We demonstrate experimentally that a growing colony of nematically ordered cells is prone to the buckling instability. Our theoretical analysis and discrete-element simulations suggest that the nature of this instability is related to the anisotropy of the stress tensor in the ordered cell colony.

Biology, population structure, and estimated forage requirements of lake trout in Lake Michigan

USGS Publications Warehouse

Eck, Gary W.; Wells, LaRue

1983-01-01

Data collected during successive years (1971-79) of sampling lake trout (Salvelinus namaycush) in Lake Michigan were used to develop statistics on lake trout growth, maturity, and mortality, and to quantify seasonal lake trout food and food availability. These statistics were then combined with data on lake trout year-class strengths and age-specific food conversion efficiencies to compute production and forage fish consumption by lake trout in Lake Michigan during the 1979 growing season (i.e., 15 May-1 December). An estimated standing stock of 1,486 metric tons (t) at the beginning of the growing season produced an estimated 1,129 t of fish flesh during the period. The lake trout consumed an estimated 3,037 t of forage fish, to which alewives (Alosa pseudoharengus) contributed about 71%, rainbow smelt (Osmerus mordax) 18%, and slimy sculpins (Cottus cognatus) 11%. Seasonal changes in bathymetric distributions of lake trout with respect to those of forage fish of a suitable size for prey were major determinants of the size and species compositions of fish in the seasonal diet of lake trout.

[COMPLICATED URINARY TRACT INFECTIONS IN THE ELDERLY].

PubMed

Ćosić, I; Ćosić, V

2016-12-01

Urinary tract infections (UTI) are the most common bacterial infections involving lower (cystitis, prostatitis) or upper (pyelonephritis, renal abscess, perinephric abscess) urinary tract. Differentiation of complicated and uncomplicated UTI is usually based on the presence of structural or functional urinary tract abnormalities, which can increase the risk of treatment failure and development of serious complications. Factors that increase the risk are foreign bodies, stones, obstruction, neurogenic bladder, kidney transplantation, immunosuppression, and pregnancy. Complicated UTI includes a spectrum of conditions that increase the risk of treatment failure, as well as of serious complications such as bacteremia and sepsis, perinephric abscess, renal impairment and emphysematous pyelonephritis. To avoid the potentially devastating outcomes, appropriate diagnostic procedures, antibiotic and surgical treatment, and appropriate follow-up are required. The incidence of complicated UTI will grow in the future due to general aging of the population, increasing incidence of diabetes, and ever growing number of immunocompromised and immunosuppressed patients. It is of key importance to recognize complicated UTI on time, and treat it wisely and aggressively to reduce duration of the disease and the risk of antibiotic resistance.

A molecular analysis of the patterns of genetic diversity in local chickens from western Algeria in comparison with commercial lines and wild jungle fowls.

PubMed

Mahammi, F Z; Gaouar, S B S; Laloë, D; Faugeras, R; Tabet-Aoul, N; Rognon, X; Tixier-Boichard, M; Saidi-Mehtar, N

2016-02-01

The objectives of this study were to characterize the genetic variability of village chickens from three agro-ecological regions of western Algeria: coastal (CT), inland plains (IP) and highlands (HL), to reveal any underlying population structure, and to evaluate potential genetic introgression from commercial lines into local populations. A set of 233 chickens was genotyped with a panel of 23 microsatellite markers. Geographical coordinates were individually recorded. Eight reference populations were included in the study to investigate potential gene flow: four highly selected commercial pure lines and four lines of French slow-growing chickens. Two populations of wild red jungle fowls were also genotyped to compare the range of diversity between domestic and wild fowls. A genetic diversity analysis was conducted both within and between populations. Multivariate redundancy analyses were performed to assess the relative influence of geographical location among Algerian ecotypes. The results showed a high genetic variability within the Algerian population, with 184 alleles and a mean number of 8.09 alleles per locus. The values of heterozygosity (He and Ho) ranged from 0.55 to 0.62 in Algerian ecotypes and were smaller than values found in Jungle fowl populations and higher than values found in commercial populations. Although the structuring analysis of genotypes did not reveal clear subpopulations within Algerian ecotypes, the supervised approach using geographical data showed a significant (p < 0.01) differentiation between the three ecotypes which was mainly due to altitude. Thus, the genetic diversity of Algerian ecotypes may be under the influence of two factors with contradictory effects: the geographical location and climatic conditions may induce some differentiation, whereas the high level of exchanges and gene flow may suppress it. Evidence of gene flow between commercial and Algerian local populations was observed, which may be due to unrecorded crossing with commercial chickens. Chicken ecotypes from western Algeria are characterized by a high genetic diversity and must be safeguarded as an important reservoir of genetic diversity. © 2015 Blackwell Verlag GmbH.

Using a Cognitive Information Processing Approach to Group Career Counseling with Visually Impaired Veterans

ERIC Educational Resources Information Center

Osborne, Lauren K.

2014-01-01

Unemployment continues to be a growing concern among both civilian and veteran populations. As 14% of the veteran population currently identify as disabled because of service, this population's need for specialized vocational rehabilitation is increasing. Specifically in Veterans Affairs (VA) Blind Rehabilitation Centers (BRC) where holistic…

The Victor-Bostrom Fund Report: Food and Population. Report No. 19, Summer-Fall 1974.

ERIC Educational Resources Information Center

Victor-Bostrom Fund Committee, Washington, DC.

Eleven articles comprise this document which presents commentaries on nutrition, population, and environmental education. The articles deal specifically with the crises of a rapidly growing world population, a worsening world food situation, and an energy crisis. A number of specific recommendations, both national and international, are offered to…

Latino Youth: Converting Challenges to Opportunities. JSRI Working Paper No. 50.

ERIC Educational Resources Information Center

Hernandez, Rudy; Siles, Marcelo; Rochin, Refugio I.

This paper examines demographic and socioeconomic data on the Latino population, focusing on characteristics of Latino youth. The U.S. Hispanic population is growing rapidly, fueled by both immigration and high fertility rates. Although census figures indicate that about 64 percent of Hispanics are of Mexican origin, the Latino population is very…

Rural Health Care in Texas: The Facts--1984.

ERIC Educational Resources Information Center

Morrison, Nolan; And Others

The size of Texas and the distribution of its population result in service delivery, economic, educational, transportation, communication, and health problems. Texas is the second largest state in the nation, is third largest in population, has a population growing at a faster rate than the national average, and is a primarily rural state--20% of…

Changes in population characteristics and their implication on public health research.

PubMed

Du, Ping; Coles, F Bruce; O'Campo, Patricia; McNutt, Louise-Anne

2007-07-10

Population estimates are generally drawn from one point in time to study disease trends over time; changes in population characteristics over time are usually not assessed and included in the study design. We evaluated whether population characteristics remained static and assessed the degree of population shifts over time. The analysis was based on the New York State 1990 and 2000 census data with adjustments for changes in geographic boundaries. Differences in census tract information were quantified by calculating the mean, median, standard deviation, and the percent of change for each population characteristic. Between 1990 and 2000, positive and negative fluctuations in population size created a U-shaped bimodal pattern of population change which increased the disparities in demographics and socioeconomic status for many census tracts. While 268 (10%) census tracts contracted by 10%, twice as many census tracts (21%, N = 557) grew at least 10%. Notably, the non-Hispanic African-American population grew 10% or more in 152 tracts. Although there were overall reductions in working class and undereducated populations and gains in incomes, most census tracts experienced growing income inequalities and an increased poverty rate. These changes were most pronounced in urban census tracts. Differences in population characteristics in a decade showed growing disparities in demographics and socioeconomic status. This study elucidates that important population shifts should be taken into account when conducting longitudinal research.

Changes in population characteristics and their implication on public health research

PubMed Central

Du, Ping; Coles, F Bruce; O'Campo, Patricia; McNutt, Louise-Anne

2007-01-01

Population estimates are generally drawn from one point in time to study disease trends over time; changes in population characteristics over time are usually not assessed and included in the study design. We evaluated whether population characteristics remained static and assessed the degree of population shifts over time. The analysis was based on the New York State 1990 and 2000 census data with adjustments for changes in geographic boundaries. Differences in census tract information were quantified by calculating the mean, median, standard deviation, and the percent of change for each population characteristic. Between 1990 and 2000, positive and negative fluctuations in population size created a U-shaped bimodal pattern of population change which increased the disparities in demographics and socioeconomic status for many census tracts. While 268 (10%) census tracts contracted by 10%, twice as many census tracts (21%, N = 557) grew at least 10%. Notably, the non-Hispanic African-American population grew 10% or more in 152 tracts. Although there were overall reductions in working class and undereducated populations and gains in incomes, most census tracts experienced growing income inequalities and an increased poverty rate. These changes were most pronounced in urban census tracts. Differences in population characteristics in a decade showed growing disparities in demographics and socioeconomic status. This study elucidates that important population shifts should be taken into account when conducting longitudinal research. PMID:17623097

Biodiversity within hot spring microbial mat communities: molecular monitoring of enrichment cultures

NASA Technical Reports Server (NTRS)

Ward, D. M.; Santegoeds, C. M.; Nold, S. C.; Ramsing, N. B.; Ferris, M. J.; Bateson, M. M.

1997-01-01

We have begun to examine the basis for incongruence between hot spring microbial mat populations detected by cultivation or by 16S rRNA methods. We used denaturing gradient gel electrophoresis (DGGE) to monitor enrichments and isolates plated therefrom. At near extincting inoculum dilutions we observed Chloroflexus-like and cyanobacterial populations whose 16S rRNA sequences have been detected in the 'New Pit' Spring Chloroflexus mat and the Octopus Spring cyanobacterial mat. Cyanobacterial populations enriched from 44 to 54 degrees C and 56 to 63 degrees C samples at near habitat temperatures were similar to those previously detected in mat samples of comparable temperatures. However, a lower temperature enrichment from the higher temperature sample selected for the populations found in the lower temperature sample. Three Thermus populations detected by both DGGE and isolation exemplify even more how enrichment may bias our view of community structure. The most abundant population was adapted to the habitat temperature (50 degrees C), while populations adapted to 65 degrees C and 70 degrees C were 10(2)- and 10(4)-fold less abundant, respectively. However, enrichment at 70 degrees C favored the least abundant strain. Inoculum dilution and incubation at the habitat temperature favored the more numerically relevant populations. We enriched many other aerobic chemoorganotrophic populations at various inoculum dilutions and substrate concentrations, most of whose 16S rRNA sequences have not been detected in mats. A common feature of numerically relevant cyanobacterial, Chloroflexus-like and aerobic chemorganotrophic populations, is that they grow poorly and resist cultivation on solidified medium, suggesting plating bias, and that the medium composition and incubation conditions may not reflect the natural microenvironments these populations inhabit.

Patterns of dynamic urban population growth in Russia, 1989-1996: a research report.

PubMed

Rowland, R H

1997-01-01

"The purpose of this paper is to investigate locations in which rapid urban growth occurred in Russia over the period 1989 to 1996....Particular emphasis will be given to the geographical patterns, economic functions, and population size of rapidly growing towns. In addition, the discussion of trends for 1989-1996 also will be briefly preceded by and compared to those of 1979-1989, although the paper will emphasize trends during the 1990s. Furthermore, the topic of ¿new towns', which themselves often are rapidly growing centers, will be addressed as well." excerpt

The Indian “girl” psychology: A perspective

PubMed Central

Rao, G. Prasad; Vidya, K. L.; Sriramya, V.

2015-01-01

India has one of the fastest growing youth populations in the world. Girls below 19 years of age comprise one-quarter of India's rapidly growing population. In spite of India's reputation for respecting women, to an extent to treat her as a goddess, the moment a baby is born, the first thing comes to mind is “boy or girl?” as the differences are beyond just being biological. This article examines the significance of various psychological constructs and psychosocial issues that are important in the life of a “girl” baby born in our country. PMID:26330637

POPULATION DYNAMICS OF CHAFF SCALE, PARLATORIA PERGANDII COMSTOCK IN COMPARATIVE ANALYSIS OF FLUCTUATING POPULATION DENSITIES ON THREE CITRUS VARIETIES IN EL-BEHEIRA GOVERNORATE, EGYPT.

PubMed

Moursi Khadiga, S; Abdel Fattah, S; Rasha; Omar, M A A; Mourad, A K

2015-01-01

Investigation throughout the subsequent years of 2011-2012 and 2012-2013 indicated that chaff scale, P. pegandii is an important economic pest on citrus trees in Abou El-Matamer area, El-Beheira Governorate, Egypt. It has been recorded in relatively high rates all over the year on three citrus varieties called Succari, Baladi and Navel oranges. Field observation and recorded data revealed that the common abundance was recorded for chaff scale on Succari oranges followed by Navel oranges then the least abundant on Baladi oranges. Generally, the calculated data on Succari oranges showed that, the population of P. pergandii reached the maximum during July and there were five highly variation periods in both the growing seasons of 2011-2012 and 2012-2013. The maximal percent of pre and adult females was observed during Spring and early Summer and reached 100% of the total counted individuals during October and December in the first year, but in the second one a higher population was recorded during Summer and early Winter months. The adult males were observed during Summer and Autumn months. Results showed also that the relationship between daily mean temperature and population density of chaff scale was weak, insignificantly negative in the two growing seasons (2011-2012 and 2012-2013) and also insignificantly but positive with relative humidity. That relationship with wind speed indicated weak positive significance in the first year and strong in the second season. The relationship between dew point and insect population was weak of positive significance in both growing seasons.

Revisiting the Iberian honey bee (Apis mellifera iberiensis) contact zone: maternal and genome-wide nuclear variations provide support for secondary contact from historical refugia.

PubMed

Chávez-Galarza, Julio; Henriques, Dora; Johnston, J Spencer; Carneiro, Miguel; Rufino, José; Patton, John C; Pinto, M Alice

2015-06-01

Dissecting diversity patterns of organisms endemic to Iberia has been truly challenging for a variety of taxa, and the Iberian honey bee is no exception. Surveys of genetic variation in the Iberian honey bee are among the most extensive for any honey bee subspecies. From these, differential and complex patterns of diversity have emerged, which have yet to be fully resolved. Here, we used a genome-wide data set of 309 neutrally tested single nucleotide polymorphisms (SNPs), scattered across the 16 honey bee chromosomes, which were genotyped in 711 haploid males. These SNPs were analysed along with an intergenic locus of the mtDNA, to reveal historical patterns of population structure across the entire range of the Iberian honey bee. Overall, patterns of population structure inferred from nuclear loci by multiple clustering approaches and geographic cline analysis were consistent with two major clusters forming a well-defined cline that bisects Iberia along a northeastern-southwestern axis, a pattern that remarkably parallels that of the mtDNA. While a mechanism of primary intergradation or isolation by distance could explain the observed clinal variation, our results are more consistent with an alternative model of secondary contact between divergent populations previously isolated in glacial refugia, as proposed for a growing list of other Iberian taxa. Despite current intense honey bee management, human-mediated processes have seemingly played a minor role in shaping Iberian honey bee genetic structure. This study highlights the complexity of the Iberian honey bee patterns and reinforces the importance of Iberia as a reservoir of Apis mellifera diversity. © 2015 John Wiley & Sons Ltd.

Exploring seascape genetics and kinship in the reef sponge Stylissa carteri in the Red Sea

PubMed Central

Giles, Emily C; Saenz-Agudelo, Pablo; Hussey, Nigel E; Ravasi, Timothy; Berumen, Michael L

2015-01-01

A main goal of population geneticists is to study patterns of gene flow to gain a better understanding of the population structure in a given organism. To date most efforts have been focused on studying gene flow at either broad scales to identify barriers to gene flow and isolation by distance or at fine spatial scales in order to gain inferences regarding reproduction and local dispersal. Few studies have measured connectivity at multiple spatial scales and have utilized novel tools to test the influence of both environment and geography on shaping gene flow in an organism. Here a seascape genetics approach was used to gain insight regarding geographic and ecological barriers to gene flow of a common reef sponge, Stylissa carteri in the Red Sea. Furthermore, a small-scale (<1 km) analysis was also conducted to infer reproductive potential in this organism. At the broad scale, we found that sponge connectivity is not structured by geography alone, but rather, genetic isolation in the southern Red Sea correlates strongly with environmental heterogeneity. At the scale of a 50-m transect, spatial autocorrelation analyses and estimates of full-siblings revealed that there is no deviation from random mating. However, at slightly larger scales (100–200 m) encompassing multiple transects at a given site, a greater proportion of full-siblings was found within sites versus among sites in a given location suggesting that mating and/or dispersal are constrained to some extent at this spatial scale. This study adds to the growing body of literature suggesting that environmental and ecological variables play a major role in the genetic structure of marine invertebrate populations. PMID:26257865

Coupled disease-behavior dynamics on complex networks: A review

NASA Astrophysics Data System (ADS)

Wang, Zhen; Andrews, Michael A.; Wu, Zhi-Xi; Wang, Lin; Bauch, Chris T.

2015-12-01

It is increasingly recognized that a key component of successful infection control efforts is understanding the complex, two-way interaction between disease dynamics and human behavioral and social dynamics. Human behavior such as contact precautions and social distancing clearly influence disease prevalence, but disease prevalence can in turn alter human behavior, forming a coupled, nonlinear system. Moreover, in many cases, the spatial structure of the population cannot be ignored, such that social and behavioral processes and/or transmission of infection must be represented with complex networks. Research on studying coupled disease-behavior dynamics in complex networks in particular is growing rapidly, and frequently makes use of analysis methods and concepts from statistical physics. Here, we review some of the growing literature in this area. We contrast network-based approaches to homogeneous-mixing approaches, point out how their predictions differ, and describe the rich and often surprising behavior of disease-behavior dynamics on complex networks, and compare them to processes in statistical physics. We discuss how these models can capture the dynamics that characterize many real-world scenarios, thereby suggesting ways that policy makers can better design effective prevention strategies. We also describe the growing sources of digital data that are facilitating research in this area. Finally, we suggest pitfalls which might be faced by researchers in the field, and we suggest several ways in which the field could move forward in the coming years.

"Growing trees backwards": Description of a stand reconstruction model (P-53)

Treesearch

Jonathan D. Bakker; Andrew J. Sanchez Meador; Peter Z. Fule; David W. Huffman; Margaret M. Moore

2008-01-01

We describe an individual-tree model that uses contemporary measurements to "grow trees backward" and reconstruct past tree diameters and stand structure in ponderosa pine dominated stands of the Southwest. Model inputs are contemporary structural measurements of all snags, logs, stumps, and living trees, and radial growth measurements, if available. Key...

"Growing trees backwards": Description of a stand reconstruction model

Treesearch

Jonathan D. Bakker; Andrew J. Sanchez Meador; Peter Z. Fule; David W. Huffman; Margaret M. Moore

2008-01-01

We describe an individual-tree model that uses contemporary measurements to "grow trees backward" and reconstruct past tree diameters and stand structure in ponderosa pine dominated stands of the Southwest. Model inputs are contemporary structural measurements of all snags, logs, stumps, and living trees, and radial growth measurements, if available. Key...

Spatial patterns of development drive water use

Treesearch

G. M. Sanchez; J. W. Smith; A. Terando; G. Sun; R. K. Meentemeyer

2018-01-01

Water availability is becoming more uncertain as human populations grow, cities expand into rural regions and the climate changes. In this study, we examine the functional relationship between water use and the spatial patterns of developed land across the rapidly growing region of the southeastern United States. We quantified the spatial pattern of developed land...

Cybernation and Man--A Course Development Project; Report Number 2. Final Report.

ERIC Educational Resources Information Center

Dionne, Edward A.; Parkman, Ralph

Transportation, Agriculture, and Art are used as examples to establish how technology, especially computer-based technology, is involved in the life of man. Cities grow in population very rapidly; motor vehicles grow in number even more rapidly; both citcumstances raise problems--traffic congestion, economic loss, air pollution, urban…

Perspectives in Early Childhood Education: Belize, Brazil, Mexico, El Salvador and Peru

ERIC Educational Resources Information Center

McConnell-Farmer, Judith Lynne; Cook, Pamela R.; Farmer, M. W.

2012-01-01

Early childhood education (ECE) provision is becoming a growing priority. During the past twenty years, Latin America has shown a growing recognition in the provision of educational programs for young children, birth to age eight, is essential. Urban and rural populations intimated in 2009, that many countries utilizing equitable access to…

QTL mapping for Cold Tolerance and Flower Type in a Reciprocal F1 Florida Avocado Mapping population

USDA-ARS?s Scientific Manuscript database

Avocado (Persea americana Mill.) farmers in South Florida have traditionally grown West Indian and Guatemalan x West Indian hybrid cultivars because they are more suitable to prevalent growing conditions. Currently, there is a growing interest in expanding the avocado production to other areas of t...

Growing up and Growing Old: Communities in Counterpoint

ERIC Educational Resources Information Center

St John, Patricia A.

2009-01-01

Using a socio-cultural lens, this study explores two unique populations participating in an intergenerational music experience: seven infants/caregivers (ages 3-16 months) and eight retired women religious (ages 70-94). I was curious to examine how music-making across ages might facilitate new-found meaning for old people whilst simultaneously…

Paxton Revisited: The Essence of the Lived Experiences of Urban Agricultural Education Students

ERIC Educational Resources Information Center

Brown, Nicholas R.; Roberts, Richie; Whiddon, Ashley S.; Goossen, Carmelita E.; Kacal, Amanda

2015-01-01

The rapidly growing world population and need for more food and agricultural knowledge has inspired city dwellers to explore urban cultivation practices such as vertical farming and community gardening. Ultra-modern approaches to growing crops and livestock in urban high-rise buildings has sparked the imagination of scientists, agriculturists, and…

Latino/a Students and Faculty Interaction: Las Voces De Persistencia

ERIC Educational Resources Information Center

Hampton, Joyce L.

2010-01-01

Latinos consistently have the lowest degree completion rate throughout the United States (Kurlaender & Flores, 2005). At the same time, Latinos are the fastest growing sector of the U.S. population. Taken together, these facts demonstrate an ongoing and growing inequity in educational opportunities and outcomes for a significant portion of the…

The New, the Newly Reborn and the Growing

ERIC Educational Resources Information Center

Reese, Susan

2005-01-01

A growing school population and deteriorating facilities are among the problems faced by the nation's educational system. Finding solutions to both the overcrowding and the crumbling condition of this nation's schools has fueled a bit of a construction boom, first among colleges and now in the nation's school districts. Within different states and…

Development of microalgae communities in the Phytotelmata of allochthonous populations of Sarracenia purpurea (Sarraceniaceae).

PubMed

Gebühr, C; Pohlon, E; Schmidt, A R; Küsel, K

2006-11-01

The phytotelmata of the North American pitcher plant Sarracenia purpurea are colonised by a great variety of aquatic organisms and, thus, provide an ideal model to study trophic interactions in small freshwater ecosystems. Although algae are discussed as a potential food source for predators, little is known about the structure of algae coenoses in pitchers of S. purpurea. This study aims to elucidate temporal shifts in the algae community structure in pitchers of an allochthonous population of S. purpurea in Saxony, Germany. A total of 78 algae taxa was found in the pitchers. Mean algae abundances in new and old pitchers were similar (2.6 x 10(5) and 2.3 x 10(5) algae ml(-1), respectively). Taxa from the orders Chlamydomonadales, Chlorococcales, and Ochromonadales were the primary colonisers. With increasing age of the pitchers the filamentous green algae from the order Klebsormidiales became more abundant. In contrast, pennate diatoms dominated the algae coenoses in the fen. Algae community structure in vase-shaped 50 ml Greiner tubes was similar to those of natural pitchers. Differences in the temporal patterns of algae coenoses in individual pitchers suggested a colonisation of the pitchers by algae via trapped insects, air and rain water rather than via the surrounding fen. Biomass of algae approximated 0.3 mg C ml(-1), which corresponds to 82.8 % of the living biomass (bacteria, heterotrophic nanoflagellates, algae, protozoans and rotifers). Rotifers were abundant in new pitchers; nematodes and mites were seldom found in all pitchers. A similar qualitative and quantitative composition of the aquatic biocoenoses was observed in pitchers of another allochthonous S. purpurea population growing in Blekinge, Sweden. Biomass of algae represented nearly one quarter of the total organic matter content in the pitchers. Thus, nitrogen and phosphorus compounds present in the algae biomass might be used by the carnivorous S. purpurea plant as additional food source in allochthonous populations in Europe lacking top predators.

[Migration and mental disorders in the Chiraguano civilization].

PubMed

Pagés Larraya, F; Servy, E; Marangunich, L

1981-03-01

The ethnographic characteristics of the Chiriguanos allowed us to make up an experimental design to show the relationship between migration and mental pathology. The Chiriguanos are a South American ethnographic population characterized by a traditional migratory tendency. The Chiriguanos group is a resultant of the Tupi-Guaraní migrations. From the 15th century up to the 19th aboriginal guaraníes moved from the current area of Paraguay to the East zone of Bolivia; they conquered and mixed with the group that lived there and after that they resisted the European forces. The Chiriguanos history can be divided in different phases: 1) The establishment in the new zone; 2) The "Chiriguana war" with the dominant group; 3) The grouping with Franciscan missions and its community organization. This study of Transcultural Psychiatry can be considered as an ex post facto experiment in the field of Psychiatric Epidemiology. It allows us to analyse population phenomena related to changes in the prevalence of mental pathology. The facts presented in this report have been established thanks to the use of sampling techniques adequated to each population being studied (original and migratory groups): demographic structure, total fertility Grow's "evolutional intensity index", and mental prevalence rates in both groups. Differences in the biennial prevalence rates of mental morbidity were found. In the original Chiriguana community there is an evident "group endogamy"; on the contrary, the migratory groups integrated by individuals of different aboriginal culture, are really melting-pots, that originate a new genetic groupal structure. We have worked with human situations created by a natural social and cultural reality. We have worked with two ethnographic homogeneous populations, one of them stable and the other a migratory one. We intended to demonstrate: 1) migration changes the rates of mental pathology; 2) those changes are followed by changes in the genetic structure of the individuals.

Sex-biased gene flow among elk in the greater Yellowstone ecosystem

USGS Publications Warehouse

Hand, Brian K.; Chen, Shanyuan; Anderson, Neil; Beja-Pereira, Albano; Cross, Paul C.; Ebinger, Michael R.; Edwards, Hank; Garrott, Robert A.; Kardos, Marty D.; Kauffman, Matthew J.; Landguth, Erin L.; Middleton, Arthur; Scurlock, Brandon M.; White, P.J.; Zager, Pete; Schwartz, Michael K.; Luikart, Gordon

2014-01-01

We quantified patterns of population genetic structure to help understand gene flow among elk populations across the Greater Yellowstone Ecosystem. We sequenced 596 base pairs of the mitochondrial control region of 380 elk from eight populations. Analysis revealed high mitochondrial DNA variation within populations, averaging 13.0 haplotypes with high mean gene diversity (0.85). The genetic differentiation among populations for mitochondrial DNA was relatively high (FST  =  0.161; P  =  0.001) compared to genetic differentiation for nuclear microsatellite data (FST  =  0.002; P  =  0.332), which suggested relatively low female gene flow among populations. The estimated ratio of male to female gene flow (mm/mf  =  46) was among the highest we have seen reported for large mammals. Genetic distance (for mitochondrial DNA pairwise FST) was not significantly correlated with geographic (Euclidean) distance between populations (Mantel's r  =  0.274, P  =  0.168). Large mitochondrial DNA genetic distances (e.g., FST > 0.2) between some of the geographically closest populations (<65 km) suggested behavioral factors and/or landscape features might shape female gene flow patterns. Given the strong sex-biased gene flow, future research and conservation efforts should consider the sexes separately when modeling corridors of gene flow or predicting spread of maternally transmitted diseases. The growing availability of genetic data to compare male vs. female gene flow provides many exciting opportunities to explore the magnitude, causes, and implications of sex-biased gene flow likely to occur in many species.

Genetic diversity and population structure of an important wild berry crop

PubMed Central

Zoratti, Laura; Palmieri, Luisa; Jaakola, Laura; Häggman, Hely

2015-01-01

The success of plant breeding in the coming years will be associated with access to new sources of variation, which will include landraces and wild relatives of crop species. In order to access the reservoir of favourable alleles within wild germplasm, knowledge about the genetic diversity and the population structure of wild species is needed. Bilberry (Vaccinium myrtillus) is one of the most important wild crops growing in the forests of Northern European countries, noted for its nutritional properties and its beneficial effects on human health. Assessment of the genetic diversity of wild bilberry germplasm is needed for efforts such as in situ conservation, on-farm management and development of plant breeding programmes. However, to date, only a few local (small-scale) genetic studies of this species have been performed. We therefore conducted a study of genetic variability within 32 individual samples collected from different locations in Iceland, Norway, Sweden, Finland and Germany, and analysed genetic diversity among geographic groups. Four selected inter-simple sequence repeat primers allowed the amplification of 127 polymorphic loci which, based on analysis of variance, made it possible to identify 85 % of the genetic diversity within studied bilberry populations, being in agreement with the mixed-mating system of bilberry. Significant correlations were obtained between geographic and genetic distances for the entire set of samples. The analyses also highlighted the presence of a north–south genetic gradient, which is in accordance with recent findings on phenotypic traits of bilberry. PMID:26483325

Population structure of Cladophora-borne Escherichia coli in nearshore water of Lake Michigan.

PubMed

Byappanahalli, Muruleedhara N; Whitman, Richard L; Shively, Dawn A; Ferguson, John; Ishii, Satoshi; Sadowsky, Michael J

2007-08-01

We previously reported that the macrophytic green alga Cladophora harbors high densities (up to 10(6) colony-forming units/g dry weight) of the fecal indicator bacteria, Escherichia coli and enterococci, in shoreline waters of Lake Michigan. However, the population structure and genetic relatedness of Cladophora-borne indicator bacteria remain poorly understood. In this study, 835 E. coli isolates were collected from Cladophora tufts (mats) growing on rocks from a breakwater located within the Indiana Dunes National Lakeshore in northwest Indiana. The horizontal fluorophore enhanced rep-PCR (HFERP) DNA fingerprinting technique was used to determine the genetic relatedness of the isolates to each other and to those in a library of E. coli DNA fingerprints. While the E. coli isolates from Cladophora showed a high degree of genetic relatedness (92% similarity), in most cases, however, the isolates were genetically distinct. The Shannon diversity index for the population was very high (5.39). Both spatial and temporal influences contributed to the genetic diversity. There was a strong association of isolate genotypes by location (79% and 80% for lake- and ditch-side samplings, respectively), and isolates collected from 2002 were distinctly different from those obtained in 2003. Cladophora-borne E. coli isolates represented a unique group, which was distinct from other E. coli isolates in the DNA fingerprint library tested. Taken together, these results indicate that E. coli strains associated with Cladophora may be a recurring source of indicator bacteria to the nearshore beach.

A homeostatic clock sets daughter centriole size in flies

PubMed Central

Aydogan, Mustafa G.; Steinacker, Thomas L.; Novak, Zsofia A.; Baumbach, Janina; Muschalik, Nadine

2018-01-01

Centrioles are highly structured organelles whose size is remarkably consistent within any given cell type. New centrioles are born when Polo-like kinase 4 (Plk4) recruits Ana2/STIL and Sas-6 to the side of an existing “mother” centriole. These two proteins then assemble into a cartwheel, which grows outwards to form the structural core of a new daughter. Here, we show that in early Drosophila melanogaster embryos, daughter centrioles grow at a linear rate during early S-phase and abruptly stop growing when they reach their correct size in mid- to late S-phase. Unexpectedly, the cartwheel grows from its proximal end, and Plk4 determines both the rate and period of centriole growth: the more active the centriolar Plk4, the faster centrioles grow, but the faster centriolar Plk4 is inactivated and growth ceases. Thus, Plk4 functions as a homeostatic clock, establishing an inverse relationship between growth rate and period to ensure that daughter centrioles grow to the correct size. PMID:29500190

Genetic diversity and geographical structure of the pitcher plant Nepenthes vieillardii in New Caledonia: A chloroplast DNA haplotype analysis.

PubMed

Kurata, Kaoruko; Jaffré, Tanguy; Setoguchi, Hiroaki

2008-12-01

Among the many species that grow in New Caledonia, the pitcher plant Nepenthes vieillardii (Nepenthaceae) has a high degree of morphological variation. In this study, we present the patterns of genetic differentiation of pitcher plant populations based on chloroplast DNA haplotype analysis using the sequences of five spacers. We analyzed 294 samples from 16 populations covering the entire range of the species, using 4660 bp of sequence. Our analysis identified 17 haplotypes, including one that is widely distributed across the islands, as well as regional and private haplotypes. The greatest haplotype diversity was detected on the eastern coast of the largest island and included several private haplotypes, while haplotype diversity was low in the southern plains region. The parsimony network analysis of the 17 haplotypes suggested that the genetic divergence is the result of long-term isolation of individual populations. Results from a spatial analysis of molecular variance and a cluster analysis suggest that the plants once covered the entire serpentine area of New Caledonia and that subsequent regional fragmentation resulted in the isolation of each population and significantly restricted seed flow. This isolation may have been an important factor in the development of the morphological and genetic variation among pitcher plants in New Caledonia.

Agricultural land usage transforms nitrifier population ecology.

PubMed

Bertagnolli, Anthony D; McCalmont, Dylan; Meinhardt, Kelley A; Fransen, Steven C; Strand, Stuart; Brown, Sally; Stahl, David A

2016-06-01

Application of nitrogen fertilizer has altered terrestrial ecosystems. Ammonia is nitrified by ammonia and nitrite-oxidizing microorganisms, converting ammonia to highly mobile nitrate, contributing to the loss of nitrogen, soil nutrients and production of detrimental nitrogen oxides. Mitigating these costs is of critical importance to a growing bioenergy industry. To resolve the impact of management on nitrifying populations, amplicon sequencing of markers associated with ammonia and nitrite-oxidizing taxa (ammonia monooxygenase-amoA, nitrite oxidoreductase-nxrB, respectively) was conducted from long-term managed and nearby native soils in Eastern Washington, USA. Native nitrifier population structure was altered profoundly by management. The native ammonia-oxidizing archaeal community (comprised primarily by Nitrososphaera sister subclusters 1.1 and 2) was displaced by populations of Nitrosopumilus, Nitrosotalea and different assemblages of Nitrososphaera (subcluster 1.1, and unassociated lineages of Nitrososphaera). A displacement of ammonia-oxidizing bacterial taxa was associated with management, with native groups of Nitrosospira (cluster 2 related, cluster 3A.2) displaced by Nitrosospira clusters 8B and 3A.1. A shift in nitrite-oxidizing bacteria (NOB) was correlated with management, but distribution patterns could not be linked exclusively to management. Dominant nxrB sequences displayed only distant relationships to other NOB isolates and environmental clones. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Phylogeographical patterns of an alpine plant, Rhodiola dumulosa (Crassulaceae), inferred from chloroplast DNA sequences.

PubMed

Hou, Yan; Lou, Anru

2014-01-01

The phylogeographical patterns of Rhodiola dumulosa, an alpine plant species restrictedly growing in the crevices of rock piles, were investigated based on 4 fragments of the chloroplast genome. To cover the full distribution of R. dumulosa in China, 19 populations from 3 major disjunct distribution areas (northern, central, and northwestern China) were sampled. A total of 5881bp (after alignment) of chloroplast DNA (cpDNA) from 100 individuals were sequenced. The combined cpDNA data set yielded 36 haplotypes. The total genetic diversity of R. dumulosa was remarkably high (H(T) = 0.981). The interpopulation genetic differentiation was significantly large (F(ST) = 0.8537, P < 0.001), possibly due to the long-term isolation of the natural populations. N(ST) was significantly larger than G(ST) (P < 0.001), indicating the presence of phylogeographical structure among the R. dumulosa populations. We propose 2 migration steps to explain the current distribution of R. dumulosa in China. First, this species migrated from refugia in the Qinghai-Tibetan Plateau to northern areas via the intervening highlands when temperatures increased; second, the highland populations migrated toward the mountaintops when temperatures increased further because R. dumulosa is adapted to cold environments. During the second migration step, the common ancestral haplotypes may have been gradually lost.

Islands within an island: repeated adaptive divergence in a single population.

PubMed

Langin, Kathryn M; Sillett, T Scott; Funk, W Chris; Morrison, Scott A; Desrosiers, Michelle A; Ghalambor, Cameron K

2015-03-01

Physical barriers to gene flow were once viewed as prerequisites for adaptive evolutionary divergence. However, a growing body of theoretical and empirical work suggests that divergence can proceed within a single population. Here we document genetic structure and spatially replicated patterns of phenotypic divergence within a bird species endemic to 250 km(2) Santa Cruz Island, California, USA. Island scrub-jays (Aphelocoma insularis) in three separate stands of pine habitat had longer, shallower bills than jays in oak habitat, a pattern that mirrors adaptive differences between allopatric populations of the species' mainland congener. Variation in both bill measurements was heritable, and island scrub-jays mated nonrandomly with respect to bill morphology. The population was not panmictic; instead, we found a continuous pattern of isolation by distance across the east-west axis of the island, as well as a subtle genetic discontinuity across the boundary between the largest pine stand and adjacent oak habitat. The ecological factors that appear to have facilitated adaptive differentiation at such a fine scale--environmental heterogeneity and localized dispersal--are ubiquitous in nature. These findings support recent arguments that microgeographic patterns of adaptive divergence may be more common than currently appreciated, even in mobile taxonomic groups like birds. © 2015 The Author(s).

Development of Malaysian women fertility index: Evidence from Shannon's entropy

NASA Astrophysics Data System (ADS)

Jalil, Wan Aznie Fatihah Wan Abd; Sharif, Shamshuritawati

2017-11-01

A fertility rate is a measure of the average number of children a woman will have during her childbearing years. Malaysia is now facing a population crisis and the fertility rate continues to decline. This situation will have implications for the age structure of the population where percentages of senior citizens are higher than percentages of people aged below 5 years old. Malaysia is expected to reach aging population status by the year 2035. As the aging population has a very long average life expectancy, the government needs to spend a lot on medical costs for senior citizens and need to increase budgets for pensions. The government may be required to increase tax revenues to support the growing older population. The falling fertility rate requires proper control by relevant authorities, especially through planning and implementation of strategic and effective measures. Hence, this paper aims to develop a fertility index using Shannon's entropy method. The results show that Selangor, Johor, and Sarawak are among the states with the highest values of the fertility index. On the other end of the spectrum, Terengganu, W.P. Labuan, and Perlis are ranked in the last positions according to the fertility index. The information generated from the results in this study can be used as a primary source for the government to design appropriate policies to mitigate dwindling fertility rates among Malaysian women.

Genetic and phenotypic variation of the malaria vector Anopheles atroparvus in southern Europe.

PubMed

Vicente, José L; Sousa, Carla A; Alten, Bulent; Caglar, Selim S; Falcutá, Elena; Latorre, José M; Toty, Celine; Barré, Hélène; Demirci, Berna; Di Luca, Marco; Toma, Luciano; Alves, Ricardo; Salgueiro, Patrícia; Silva, Teresa L; Bargues, Maria D; Mas-Coma, Santiago; Boccolini, Daniela; Romi, Roberto; Nicolescu, Gabriela; do Rosário, Virgílio E; Ozer, Nurdan; Fontenille, Didier; Pinto, João

2011-01-11

There is a growing concern that global climate change will affect the potential for pathogen transmission by insect species that are vectors of human diseases. One of these species is the former European malaria vector, Anopheles atroparvus. Levels of population differentiation of An. atroparvus from southern Europe were characterized as a first attempt to elucidate patterns of population structure of this former malaria vector. Results are discussed in light of a hypothetical situation of re-establishment of malaria transmission. Genetic and phenotypic variation was analysed in nine mosquito samples collected from five European countries, using eight microsatellite loci and geometric morphometrics on 21 wing landmarks. Levels of genetic diversity were comparable to those reported for tropical malaria vectors. Low levels of genetic (0.004

A diverse and intricate signalling network regulates stem cell fate in the shoot apical meristem.

PubMed

Dodsworth, Steven

2009-12-01

At the shoot apex of plants is a small region known as the shoot apical meristem (SAM) that maintains a population of undifferentiated (stem) cells whilst providing cells for developing lateral organs and the stem. All aerial structures of the plant develop from the SAM post-embryogenesis, enabling plants to grow in a characteristic modular fashion with great phenotypic and developmental plasticity throughout their lifetime. The maintenance of the stem cell population is intimately balanced with cell recruitment into differentiating tissues through intercellular communication involving a complex signalling network. Recent studies have shown that diverse regulators function in SAM maintenance, many of which converge on the WUSCHEL (WUS) gene. In this review the diverse regulatory modules that function in SAM maintenance are discussed: transcriptional and epigenetic control, hormonal regulation, and the balance with organogenesis. The central role of WUS as an integrator of multiple signals is highlighted; in addition, accessory feedback loops emerge as a feature enabling dynamic regulation of the stem cell niche.

Genetic structure of Cantharellus formosus populations in a second-growth temperate rain forest of the Pacific Northwest

USGS Publications Warehouse

Redman, Regina S.; Ranson, Judith; Rodriguez, Rusty J.

2006-01-01

Cantharellus formosus growing on the Olympic Peninsula of the Pacific Northwest was sampled from September – November 1995 for genetic analysis. A total of ninety-six basidiomes from five clusters separated from one another by 3 - 25 meters were genetically characterized by PCR analysis of 13 arbitrary loci and rDNA sequences. The number of basidiomes in each cluster varied from 15 to 25 and genetic analysis delineated 15 genets among the clusters. Analysis of variance utilizing thirteen apPCR generated genetic molecular markers and PCR amplification of the ribosomal ITS regions indicated that 81.41% of the genetic variation occurred between clusters and 18.59% within clusters. Proximity of the basidiomes within a cluster was not an indicator of genotypic similarity. The molecular profiles of each cluster were distinct and defined as unique populations containing 2 - 6 genets. The monitoring and analysis of this species through non-lethal sampling and future applications is discussed.

Microbial communities in the litter of middle taiga bilberry-spruce forests

NASA Astrophysics Data System (ADS)

Sizonenko, T. A.; Zagirova, S. V.; Khabibullina, F. M.

2010-10-01

The structure of the microbial communities in the litters of middle-taiga bilberry-spruce forests was studied. It was found that ammonifying and oligonitrophilic microorganisms predominate in these communities. Two maximums in the population density of the microorganisms were observed in June and August. The number of microorganisms increased in the direction from the spruce trunks to the periphery of the crowns. The species composition of the micromycetes in the litters under the spruce crowns and within the intercrown spaces differed. The maximum population density of the fungi was found in the litter under the periphery of the spruce crowns, whereas the maximum diversity of the micromycetes was observed within the intercrown spaces. The Trichoderma, Trichosporiella, Penicillium, Paecilomyces, and Chaetomium genera were most abundant in the litters of the bilberry spruce forests. The Penicillium genus had the maximum abundance during the entire growing period, and the amount of Mycelia sterilia increased in the fall. The maximum diversity of the fungi was observed in May and June.

Age, growth rates, and paleoclimate studies of deep sea corals

USGS Publications Warehouse

Prouty, Nancy G; Roark, E. Brendan; Andrews, Allen; Robinson, Laura; Hill, Tessa; Sherwood, Owen; Williams, Branwen; Guilderson, Thomas P.; Fallon, Stewart

2015-01-01

Deep-water corals are some of the slowest growing, longest-lived skeletal accreting marine organisms. These habitat-forming species support diverse faunal assemblages that include commercially and ecologically important organisms. Therefore, effective management and conservation strategies for deep-sea corals can be informed by precise and accurate age, growth rate, and lifespan characteristics for proper assessment of vulnerability and recovery from perturbations. This is especially true for the small number of commercially valuable, and potentially endangered, species that are part of the black and precious coral fisheries (Tsounis et al. 2010). In addition to evaluating time scales of recovery from disturbance or exploitation, accurate age and growth estimates are essential for understanding the life history and ecology of these habitat-forming corals. Given that longevity is a key factor for population maintenance and fishery sustainability, partly due to limited and complex genetic flow among coral populations separated by great distances, accurate age structure for these deep-sea coral communities is essential for proper, long-term resource management.

Sending-country violence and receiving-country discrimination: effects on the health of Colombian refugees in Ecuador.

PubMed

Shedlin, Michele G; Decena, Carlos U; Noboa, Hugo; Betancourt, Óscar

2014-02-01

This study explored factors affecting the health and well being of recent refugees from Colombia in Ecuador. Data collection focused on how sending-country violence and structural violence in a new environment affect immigrant health vulnerability and risk behaviors. A qualitative approach included ethnographic observation, media content analysis, focus groups, and individual interviews with refugees (N = 137). The focus groups (5) provided perspectives on the research domains by sex workers; drug users; male and female refugees; and service providers. Social and economic marginalization are impacting the health and well being of this growing refugee population. Data illustrate how stigma and discrimination affect food and housing security, employment and health services, and shape vulnerabilities and health risks in a new receiving environment. Widespread discrimination in Ecuador reflects fears, misunderstanding, and stereotypes about Colombian refugees. For this displaced population, the sequelae of violence, combined with survival needs and lack of support and protections, shape new risks to health and well-being.

Solution of the spatial neutral model yields new bounds on the Amazonian species richness

NASA Astrophysics Data System (ADS)

Shem-Tov, Yahav; Danino, Matan; Shnerb, Nadav M.

2017-02-01

Neutral models, in which individual agents with equal fitness undergo a birth-death-mutation process, are very popular in population genetics and community ecology. Usually these models are applied to populations and communities with spatial structure, but the analytic results presented so far are limited to well-mixed or mainland-island scenarios. Here we combine analytic results and numerics to obtain an approximate solution for the species abundance distribution and the species richness for the neutral model on continuous landscape. We show how the regional diversity increases when the recruitment length decreases and the spatial segregation of species grows. Our results are supported by extensive numerical simulations and allow one to probe the numerically inaccessible regime of large-scale systems with extremely small mutation/speciation rates. Model predictions are compared with the findings of recent large-scale surveys of tropical trees across the Amazon basin, yielding new bounds for the species richness (between 13100 and 15000) and the number of singleton species (between 455 and 690).

Sending-Country Violence & Receiving-Country Discrimination: Effects on the Health of Colombian Refugees in Ecuador

PubMed Central

Shedlin, Michele G.; Decena, Carlos U.; Noboa, Hugo; Betancourt, Óscar

2013-01-01

BACKGROUND This study explored factors affecting the health and well being of recent refugees from Colombia in Ecuador. Data collection focused on how sending-country violence and structural violence in a new environment affect immigrant health vulnerability and risk behaviors. METHODS A qualitative approach included ethnographic observation, media content analysis, focus groups, and individual interviews with refugees (N=137). The focus groups (5) provided perspectives on the research domains by sex workers; drug users; male and female refugees; and service providers. RESULTS Social and economic marginalization are impacting the health and well being of this growing refugee population. Data illustrate how stigma and discrimination affect food and housing security, employment and health services, and shape vulnerabilities and health risks in a new receiving environment. DISCUSSION Widespread discrimination in Ecuador reflects fears, misunderstanding, and stereotypes about Colombian refugees. For this displaced population, the sequelae of violence, combined with survival needs and lack of support and protections, shape new risks to health and well-being. PMID:23377565

Mechanisms and functions of brain and behavioural asymmetries

PubMed Central

Tommasi, Luca

2008-01-01

For almost a century the field of brain and behavioural asymmetries has been dominated by studies on humans, resting on the evidence that the anatomical structures underlying language functions are asymmetrical, and that human handedness is lateralized at the population level. Today, there is not only evidence of population-level lateralization of brain and behaviour across a variety of vertebrate and invertebrate species, but also a growing consensus that the comparative analysis of the environmental and developmental factors that give origin to neural and behavioural laterality in animal models, together with theoretical analyses of their costs and benefits, will be crucial for understanding the evolutionary pathways that led to such a multifaceted phenomenon. The present theme issue provides a survey of theoretical, review and research work cutting across the biological and the cognitive sciences, focusing on various species of fishes, birds and primates (including humans) and emphasizing an integrative approach to the study of lateralization encompassing neural, behavioural, cognitive, developmental and environmental aspects. PMID:19064348

Odour dialects among wild mammals.

PubMed

Kean, Eleanor Freya; Bruford, Michael William; Russo, Isa-Rita M; Müller, Carsten Theodor; Chadwick, Elizabeth Anna

2017-10-19

Across multiple taxa, population structure and dynamics depend on effective signalling between individuals. Among mammals, chemical communication is arguably the most important sense, underpinning mate choice, parental care, territoriality and even disease transmission. There is a growing body of evidence that odours signal genetic information that may confer considerable benefits including inbreeding avoidance and nepotism. To date, however, there has been no clear evidence that odours encode population-level information in wild mammals. Here we demonstrate for the first time the existence of 'odour dialects' in genetically distinct mammalian subpopulations across a large geographical scale. We found that otters, Lutra lutra, from across the United Kingdom possess sex and biogeography-specific odours. Subpopulations with the most distinctive odour profiles are also the most genetically diverse but not the most genetically differentiated. Furthermore, geographic distance between individuals does not explain regional odour differences, refuting other potential explanations such as group odour sharing behaviour. Differences in the language of odours between subpopulations have the potential to affect individual interactions, which could impact reproduction and gene-flow.

Modeling mechanical interactions in growing populations of rod-shaped bacteria

NASA Astrophysics Data System (ADS)

Winkle, James J.; Igoshin, Oleg A.; Bennett, Matthew R.; Josić, Krešimir; Ott, William

2017-10-01

Advances in synthetic biology allow us to engineer bacterial collectives with pre-specified characteristics. However, the behavior of these collectives is difficult to understand, as cellular growth and division as well as extra-cellular fluid flow lead to complex, changing arrangements of cells within the population. To rationally engineer and control the behavior of cell collectives we need theoretical and computational tools to understand their emergent spatiotemporal dynamics. Here, we present an agent-based model that allows growing cells to detect and respond to mechanical interactions. Crucially, our model couples the dynamics of cell growth to the cell’s environment: Mechanical constraints can affect cellular growth rate and a cell may alter its behavior in response to these constraints. This coupling links the mechanical forces that influence cell growth and emergent behaviors in cell assemblies. We illustrate our approach by showing how mechanical interactions can impact the dynamics of bacterial collectives growing in microfluidic traps.

Earthquake vulnerability assessment of buildings of ward no. 8 of Haldwani-Kathgodam Municipal Corporation, Uttarakhand, India

NASA Astrophysics Data System (ADS)

Bora, Kritika; Pande, Ravindra K.

2017-07-01

"Earthquake does not kill people; it is the building which kills people". Earthquake is a sudden event below the surface of the earth which results in vertical and horizontal waves that causes destruction. The main aim of this research is to bring into light the unplanned and non-engineered construction practices growing in the Urban areas. Lack of space and continuous migration from hills has resulted in Multistorey construction. The present study is based on primary data collection through Rapid Visual Screening for the assessment of vulnerability of buildings. "Haldwani-Kathgodam being a new Municipal Corporation located in the foot hills of Himalayas is facing same problem. The seismic zonation brings this area into zone 4 of damage risk. Therefore an assessment to estimate the risk of the built up environment is important. This paper presents a systematic and useful way of assessing physical vulnerability of buildings. The present paper will show how the growing pressure on urban area tends to make the built up environment vulnerable towards seismic activities. The challenge today is to make our living environment safe for living. The day by day growing population pressure on urban area as a migration trend in developing countries is leading to high rise building, no planning and reckless construction. For the sake of saving some money people usually do not take the approval from structural engineer. This unplanned and haphazard construction proves non-resistant towards earthquake and brings lives and properties to death and a stand still. The total no. of household in the current study area is 543 whereas the total population is 2497 (2011). The recent formation of Himalayas makes the area more sensitive towards seismic event. The closeness to the Main Boundary thrust brings it to zone 4 in the Seismic Zonation of India i.e., High Damage Risk Zone

Evolution in an Afternoon: Rapid Natural Selection and Adaptation of Bacterial Populations

ERIC Educational Resources Information Center

Delpech, Roger

2009-01-01

This paper describes a simple, rapid and low-cost technique for growing bacteria (or other microbes) in an environmental gradient, in order to determine the tolerance of the microbial population to varying concentrations of sodium chloride ions, and suggests how the evolutionary response of a microbial population to the selection pressure of the…

Planet Earth, 1984-2034: A Demographic Vision.

ERIC Educational Resources Information Center

Bouvier, Leon F.

1984-01-01

In recognition of the 1984 World Population Conference, this booklet examines the current state of world population and presents speculations on what it might be 50 years from now. World population, now close to 4.8 billion and growing at 1.8 percent a year, is being shaped by three demographic phenomena: prolonged below-replacement fertility in…

Growing hickories (Carya spp.) for roost trees: A method to support conservation of declining bat populations

Treesearch

Tara Luna; Daniel L. Lindner; R. Kasten Dumroese

2014-01-01

Bats (Vespertilionidae and Phyllostomidae) are a critically important component of North American ecosystems. These insectivorous mammals provide largely unrecognized ecosystem services to agriculture and forest health and sustain bat-dependent native plant populations. The decline of North American bat populations reflects the recent emergence of the fungal disease...

International Assistance in the Population Field: Roads Taken, Paths Ahead. Occasional Paper Series, Number 7, Volume II.

ERIC Educational Resources Information Center

Zeidenstein, George

American attitudes toward foreign aid for population control have changed dramatically since the period following World War II, when birth control assistance was considered too controversial for government funding. With growing national and international concern about population growth and poverty in the developing nations and through the efforts…

Numbers, Numbers, Numbers: The Role of Population Studies in Social Studies and Global Education

ERIC Educational Resources Information Center

Moore, James R.

2008-01-01

Population trends--birth and death rates, immigration patterns, sex ratios, and life expectancies--are one of the most important issues facing the international community. These trends' relationship to the world economy, the environment, and developing countries' ability to meet the needs of growing populations is a topic appropriate for the…

Educational Journeys of Hispanic Women in Nursing

ERIC Educational Resources Information Center

Herrera, Antoinette Navalta

2012-01-01

Hispanics continue to be the fastest growing minority population in the Nation. According to U.S. Census Bureau (2011; 2008), the Hispanic or Latino population was 16.3 percent in 2010 and is projected to be over 30 percent in 2050. However, only 3.6% of the RN population is Hispanic indicating an unrealistic representation of today's…

Modeling mechanical inhomogeneities in small populations of proliferating monolayers and spheroids.

PubMed

Lejeune, Emma; Linder, Christian

2018-06-01

Understanding the mechanical behavior of multicellular monolayers and spheroids is fundamental to tissue culture, organism development, and the early stages of tumor growth. Proliferating cells in monolayers and spheroids experience mechanical forces as they grow and divide and local inhomogeneities in the mechanical microenvironment can cause individual cells within the multicellular system to grow and divide at different rates. This differential growth, combined with cell division and reorganization, leads to residual stress. Multiple different modeling approaches have been taken to understand and predict the residual stresses that arise in growing multicellular systems, particularly tumor spheroids. Here, we show that by using a mechanically robust agent-based model constructed with the peridynamic framework, we gain a better understanding of residual stresses in multicellular systems as they grow from a single cell. In particular, we focus on small populations of cells (1-100 s) where population behavior is highly stochastic and prior investigation has been limited. We compare the average strain energy density of cells in monolayers and spheroids using different growth and division rules and find that, on average, cells in spheroids have a higher strain energy density than cells in monolayers. We also find that cells in the interior of a growing spheroid are, on average, in compression. Finally, we demonstrate the importance of accounting for stochastic fluctuations in the mechanical environment, particularly when the cellular response to mechanical cues is nonlinear. The results presented here serve as a starting point for both further investigation with agent-based models, and for the incorporation of major findings from agent-based models into continuum scale models when explicit representation of individual cells is not computationally feasible.

Accountability for the Quality of Care Provided to People with Serious Illness

PubMed Central

Hudson Scholle, Sarah; Briefer French, Jessica

2018-01-01

Abstract Background: Care for patients with serious illness is an emerging practice area that has gained attention as value-based purchasing has increased. While the number of programs is growing, their impact on care quality and outcomes is unknown. Objective: With support from the Gordon and Betty Moore Foundation, the National Committee for Quality Assurance (NCQA) is assessing the feasibility of creating an accountability program focused on serious illness care. Methods: This article describes the process of developing an accountability program, findings from our initial work, and our plans to develop measures for a serious illness care accountability program. We focused on three questions: 1. What patient populations should be targeted for measurement?2. What entities have accountability for ensuring high-quality care for serious illness?3. What structures, processes, and outcomes should be evaluated in an accountability program for serious illness care? Results: Our environmental scan showed that the evidence base for specific patient populations or care models is not sufficiently mature to justify traditional structure and process measures. In visits to serious illness care programs, we observed different staffing models, care models, care settings, and payment structures. We found a gap between recommended inclusion criteria and services when compared to inclusion criteria and services offered by existing programs. Conclusions: To address the challenges, NCQA intends to develop outcome measures driven by patient and family priorities. Structure and process measures will focus on building organizations' capacity to measure outcomes, including patient engagement and outcomes, linked to patient goals. PMID:29313755

Will human populations be limited by food?

NASA Astrophysics Data System (ADS)

Warren, S. G.

2016-12-01

Historical examples of demographic change, in China, Italy, Nigeria, Utah, the Philippines, and elsewhere, together with simple mathematics and biological principles, show that stabilizing world population before it is limited by food supply will be more difficult than is generally appreciated. United Nations population projections are based on a logical fallacy in that they assume, in spite of the absence of necessary negative feedbacks, that all nations will converge rapidly to replacement-level fertility and thereafter remain at that level. The benign projections that have resulted from this assumption may have hindered efforts to make availability of birth-control a priority in development-aid. Education of women and provision of contraceptives have caused dramatic reductions in fertility, but many groups, including some that are well-educated, maintain high fertility. Small groups with persistent high fertility can grow to supplant low-fertility groups, resulting in continued growth of the total population. The global average fertility rate could rise even if each country's fertility rate is falling. In some low-fertility European countries where deaths exceed births, the population continues to grow because of immigration. Producing more than two offspring is normal for all animal species with stable populations, because their populations are limited by resources or predation rather than birth control. It may therefore be appropriate to view the growth of human population as the result not of excess fertility but rather of excess food. Even if the fertility rate is maintained far in excess of 2, the population cannot grow if food is limiting. Without the agricultural advances of the 20thcentury, world population could not have grown as it did from 1.7 billion in 1900 to 6 billion in 2000. The food supply may be enhanced in the future by genetic engineering and other innovations, but it may be limited by water shortage, climate change, pollution, and energy shortage. The efficiency of agriculture may be diminished by breakdown of social infrastructure. References: S.G. Warren, 2015: Can human populations be stabilized? Earth's Future 3, 82-94, doi:10.1002/2014EF000275 S.G. Warren, 2016: Reply to comment, Earth's Future 4, 18-19, doi:10.1002/2015EF000341

Projections of the Size and Composition of the U.S. Population: 2014 to 2060. Population Estimates and Projections. Current Population Reports. P25-1143

ERIC Educational Resources Information Center

Colby, Sandra L.; Ortman, Jennifer M.

2015-01-01

Between 2014 and 2060, the U.S. population is projected to increase from 319 million to 417 million, reaching 400 million in 2051. The U.S. population is projected to grow more slowly in future decades than in the recent past, as these projections assume that fertility rates will continue to decline and that there will be a modest decline in the…

Population Change Within Nonmetropolitan and Metropolitan Areas: Lessons from New York State.

ERIC Educational Resources Information Center

Moore, Dan E.

According to the results of an in-depth study of the process of population change in New York State, the less densely settled an area, the more likely it is to grow in the 1970's. This is more evidence of the recent major U.S. demographic phenomenon of a revival of population growth in non-metropolitan areas. Population data for the sixty-two…

Population Issues: From Obscurity to Worldwide Interest. Population: Before and after Bucharest [And] Ford Foundation Programs: Review and Projection. A Ford Foundation Reprint.

ERIC Educational Resources Information Center

Saunders, Lyle; Harkavy, Oscar

This essay traces the actions taken by governments and private agencies in the past two decades to limit population growth and examines the growing emphasis on linking population and development concerns. It was presented to the annual conference of the Ford Foundation's International Division on September 22, 1975. The time between the end of…

Diverse Hispanic population to become largest U.S. minority.

PubMed

1997-11-01

High immigration rates and relatively high birth rates have made Hispanics the second fastest growing minority population in the US. Only the Asian population is growing faster. In 1996, 11% of the US's population was Hispanic. However, Hispanic Americans are projected to outnumber African Americans by 2005, and by 2050, the Hispanic population in the US is projected to total approximately 100 million, 25% of the US population and the largest of the country's ethnic minorities. Latinos have the lowest rates of high school and college graduation of any major population group in the US. Since relevant data first became available in 1972 and until 1994, the median income of Latino families has remained below that of White families, but above that of African American families. The Hispanics' median family income of $24,000 in 1995 was below that of African American families. Puerto Rican and Mexican families are most likely to be poor, while Cubans are least likely. There is considerable diversity within the US's Hispanic population. For example, some Hispanics speak only Spanish, while others speak no Spanish at all. Hispanic Americans come from many countries and cultures, making the differences between and within the Hispanic ethnic groups sometimes as great as their similarities. Most Americans do not understand that Hispanics are an ethnic group, not a racial group.

Aging and differentiation in yeast populations: elders with different properties and functions.

PubMed

Palková, Zdena; Wilkinson, Derek; Váchová, Libuše

2014-02-01

Over the past decade, it has become evident that similarly to cells forming metazoan tissues, yeast cells have the ability to differentiate and form specialized cell types. Examples of yeast cellular differentiation have been identified both in yeast liquid cultures and within multicellular structures occupying solid surfaces. Most current knowledge on different cell types comes from studies of the spatiotemporal internal architecture of colonies developing on various media. With a few exceptions, yeast cell differentiation often concerns nongrowing, stationary-phase cells and leads to the formation of cell subpopulations differing in stress resistance, cell metabolism, respiration, ROS production, and others. These differences can affect longevity of particular subpopulations. In contrast to liquid cultures, where various cell types are dispersed within stationary-phase populations, cellular differentiation depends on the specific position of particular cells within multicellular colonies. Differentiated colonies, thus, resemble primitive multicellular organisms, in which the gradients of certain compounds and the position of cells within the structure affect cellular differentiation. In this review, we summarize and compare the properties of diverse types of differentiated chronologically aging yeast cells that have been identified in colonies growing on different media, as well as of those found in liquid cultures. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Social structure and group dynamics of the Cao Vit gibbon (Nomascus nasutus) in Bangliang, Jingxi, China.

PubMed

Fan, Pengfei; Fei, Hanlan; Xiang, Zuofu; Zhang, Wen; Ma, Changyong; Huang, Tao

2010-01-01

The Cao Vit gibbon (Nomascus nasutus) was rediscovered in 2002 in Vietnam and then in 2006 in China. This is the only known population with about 110 individuals located along the China-Vietnam border. Little is known about it other than its population size and distribution. We describe the social structure and group dynamics of the Cao Vit gibbons in China based on 2 years of monitoring from 2007 to 2009. Four established study groups at this site consisted of 1 adult male, 2 adult females and 2-6 offspring. Two juveniles in 2 groups disappeared during the research. Four infants were born in 3 groups from November 2008 to February 2009. In 2 of the groups, both adult females had dependent infants. These observations suggest that Cao Vit gibbons live in polygynous groups, contrary to the usual monogamous group with only 1 adult female, but nevertheless similar to the social organization of both N. concolor and N. hainanus. We observed a coordinated dispersal of 1 adult male and 2 large juveniles, and the male formed a pair with a newly arrived female. Our observations support a growing awareness of variability in gibbon social organization. Copyright © 2010 S. Karger AG, Basel.

[Demographic profile of Venezuela].

PubMed

Quintero, I

1984-04-01

Sources of demographic data for Venezuela include 11 population censuses conducted between 1873-1981, birth and death registration statistics, and the household sample survey. The average annual rate of population growth increase from 2.8% between 1920-40 to 3-4% thereafter. The population at the 1961 census was 7.52 million. According to preliminary data from the 1981 census, the population of 14.57 million is growing at an annual rate of 2.8%. 41.2% of the population is under 15 years old, implying a huge demand for educational and health services, housing and employment. The dependency rate in 1980 was 81.3% for the country as a whole, 100.4% in rural areas, and 76.0% in urban areas. The young age structure means that the population will continue to grow even if natality rates decline. The crude natality rate was estimated at 47.3/1000 for 1950-55, 36.0 for 1970-75, and 32.9 for 1980-85. Some rural areas still have natality rates of over 47/1000. The total fertility rate declined from 6.5 in 1950-55 to 4.1 in 1980-85. The decline in the natality rate reflects improving quality of life, availability of family planning services, urbanization, and access of women to productive activities and educational centers. The mortality rate was 12.3/1000 in 1950-55, 9.1 in 1960-65, in 1970-75, and has been estimated at 5.5 for 1980-85. Some rural areas have mortality rates of 8.1. The infant mortality rate was 50.2/1000 in 1971 and 34.3 in 1980. Life expectancy at birth is about 69 years. During the 1920s, Venezuela unerwent expansion in infrastructure and technological utilization, generating rapid urbanization. 39.2% of the population was urban in 1941, compared to 78.8% in 1980. The significance of urbanization in Venezuela is due to the rapidity as well as the diffusion of the process. The household sample survey for the 2nd half of 1980 indicated a total of 8.16 million employed and an activity rate of 32.1% overall, 46.4% for males and 17.7% for females. The demographic situation of Venezuela does not appear alarming if viewed in isolation, but the deficit of some 500,000 housing units, the million unemployed, the importation of about 75% of the country's food, the stagnation of agriculture, the lower than subsistence level of about 40% of incomes, and the lack of population policies suggest that the 24.7 million inhabitants projected for 2000 will pose a considerable challenge to the nation.

THE GOBAL CHANGE AIR QUALITY ASSESSMENT: BACKGROUND AND OVERVIEW OF INTRAMURAL WORK

EPA Science Inventory

Factors such as population growth and migration, economic expansion, land use, resource availability, climate change, and technology change impact environmental quality and human health. With populations expected to continue to grow, and with additional countries joining the ran...

International Students' Confidence and Academic Success

ERIC Educational Resources Information Center

Telbis, Nicola Miky; Helgeson, Lars; Kingsbury, Cheryl

2014-01-01

Research shows that the international student population is showing significant growth. This article deals with issues affecting a growing international student population. Studies show that foreign students are encountering difficulties in social adaptability, language barriers, academic ability, and financial need. There is evidence that a…

Nitrogen Leaching Index

USDA-ARS?s Scientific Manuscript database

World agricultural production will have to increase significantly during the next few decades to keep up with the increasing demands for food brought about by a growing human population. Increases in agricultural production will be required not only to supply grain for a larger world population, but...

Energy Awareness and Scheduling in Mobile Devices and High End Computing

ERIC Educational Resources Information Center

Pawaskar, Sachin S.

2013-01-01

In the context of the big picture as energy demands rise due to growing economies and growing populations, there will be greater emphasis on sustainable supply, conservation, and efficient usage of this vital resource. Even at a smaller level, the need for minimizing energy consumption continues to be compelling in embedded, mobile, and server…

Growing Plants and Scientists: Fostering Positive Attitudes toward Science among All Participants in an Afterschool Hydroponics Program

ERIC Educational Resources Information Center

Patchen, Amie K.; Zhang, Lin; Barnett, Michael

2017-01-01

This study examines an out-of-school time program targeting elementary-aged youth from populations that are typically underrepresented in science fields (primarily African-American, Hispanic, and/or English Language Learner participants). The program aimed to foster positive attitudes toward science among youth by engaging them in growing plants…

Sage-Grouse and Coal-Bed Methane: Can They Coexist within the Powder River Basin?

ERIC Educational Resources Information Center

Duncan, Michael B.

2010-01-01

Concerns are growing regarding the availability of sustainable energy sources due to a rapidly growing human population and a better understanding of climate change. In recent years, the United States has focused much attention on developing domestic energy sources, which include coal-bed methane (CBM). There are vast deposits of the natural gas…

Biology and ecology of red alder.

Treesearch

Constance A. Harrington

2006-01-01

Red alder is the most common hardwood in the Pacific Northwest with a range stretching from coastal southeast Alaska to southern California and east to isolated populations in Idaho. Soil moisture during the growing season influences where it grows and its growth rates; it can tolerate poor drainage but not droughty, hot sites. Due to its tolerance of wet soil...

English Teaching and the Economic Development of Colombia.

ERIC Educational Resources Information Center

Stansfield, Charles W.

To supply the large number of workers qualified for complex jobs, a demand created by the growing needs of a rapidly growing population, Colombia must make provisions for an expanded system of higher education. This can be accomplished by sending students abroad to study at the university level. The large number of students coming to the United…

Increasing English Language Learners' Engagement in Instruction through Emotional Scaffolding

ERIC Educational Resources Information Center

Park, Mi-Hwa

2014-01-01

Some of the challenges that early childhood teachers face include how to deal with a growing diversity in student populations, how to reduce learning gaps, and how to increase the achievement of all children (Copple & Bredekamp, 2009). The number of children who are English language learners (ELLs) is growing fast schools in the United States…

Information Literacy and the 21st Century Academic Librarian: A Delphi Study

ERIC Educational Resources Information Center

Dixon-Thomas, Courtlann

2012-01-01

An emphasis on instruction has been growing in libraries as a result of the cumbersome amount of information that is produced and available globally. This, coupled with the growing diverse student populations and the demand for higher education, has created the need for students entering the workforce who can think critically, adapt quickly and…

Active population growth and immigration hypotheses in Western Europe.

PubMed

Feld, S

2000-03-01

The paper examines, in respect of 12 Western European countries over a period of 20 years, the widely held view that any decline in their working population should be offset by greater reliance on immigrant labor. This research, based on demographic projections and forecasts regarding labor market participation rates by age and sex for each of the countries concerned, focuses on the two most likely scenarios. It appears that only Italy will be faced with a fall in its working population. All other western countries will either maintain the same level or, more generally, see their workforce grow substantially. Accordingly, the authors may safely assert that there is no risk of a shortage of workers between now and the year 2020, and that an increasing supply of labor will render reliance on a greater influx of immigrant workers unnecessary. The second part analyses changes in the structure of the demand for labor. The authors deal chiefly with the phenomenon of the concentration of foreign manpower in each sector, its flexibility and mobility in a context of unemployment, as well as the impact of new technologies and globalization on the main determinants of international migration of labor.

Disruptive innovation in academic medical centers: balancing accountable and academic care.

PubMed

Stein, Daniel; Chen, Christopher; Ackerly, D Clay

2015-05-01

Numerous academic medicine leaders have argued that academic referral centers must prepare for the growing importance of accountability-driven payment models by adopting population health initiatives. Although this shift has merit, execution of this strategy will prove significantly more problematic than most observers have appreciated. The authors describe how successful implementation of an accountable care health strategy within a referral academic medical center (AMC) requires navigating a critical tension: The academic referral business model, driven by tertiary-level care, is fundamentally in conflict with population health. Referral AMCs that create successful value-driven population health systems within their organizations will in effect disrupt their own existing tertiary care businesses. The theory of disruptive innovation suggests that balancing the push and pull of academic and accountable care within a single organization is achievable. However, it will require significant shifts in resource allocation and changes in management structure to enable AMCs to make the inherent difficult choices and trade-offs that will ensue. On the basis of the theories of disruptive innovation, the authors present recommendations for how academic health systems can successfully navigate these issues as they transition toward accountability-driven care.

The multilocus sequence typing network: mlst.net.

PubMed

Aanensen, David M; Spratt, Brian G

2005-07-01

The unambiguous characterization of strains of a pathogen is crucial for addressing questions relating to its epidemiology, population and evolutionary biology. Multilocus sequence typing (MLST), which defines strains from the sequences at seven house-keeping loci, has become the method of choice for molecular typing of many bacterial and fungal pathogens (and non-pathogens), and MLST schemes and strain databases are available for a growing number of prokaryotic and eukaryotic organisms. Sequence data are ideal for strain characterization as they are unambiguous, meaning strains can readily be compared between laboratories via the Internet. Laboratories undertaking MLST can quickly progress from sequencing the seven gene fragments to characterizing their strains and relating them to those submitted by others and to the population as a whole. We provide the gateway to a number of MLST schemes, each of which contain a set of tools for the initial characterization of strains, and methods for relating query strains to other strains of the species, including clustering based on differences in allelic profiles, phylogenetic trees based on concatenated sequences, and a recently developed method (eBURST) for identifying clonal complexes within a species and displaying the overall structure of the population. This network of MLST websites is available at http://www.mlst.net.

Workforce ethnic diversity and culturally competent health care: the case of Arab physicians in Israel.

PubMed

Popper-Giveon, Ariela; Liberman, Ido; Keshet, Yael

2014-01-01

In recent years, a growing body of literature has been calling for ethnic diversity in health systems, especially in multicultural contexts. Ethnic diversity within the health care workforce is considered to play an important role in reducing health disparities among different ethnic groups. The present study explores the topic using quantitative data on participation of Arab employees in the Israeli health system and qualitative data collected through semi-structured interviews with Arab physicians working in the predominantly Jewish Israeli health system. We show that despite the underrepresentation of Arabs in the Israeli health system, Arab physicians who hold positions in Israeli hospitals do not perceive themselves as representatives of the Arab sector; moreover, they consider themselves as having broken through the 'glass ceiling' and reject stereotyping as Arab 'niche doctors.' We conclude that minority physicians may prefer to promote culturally competent health care through integration and advocacy of interaction with the different cultures represented in the population, rather than serving as representatives of their own ethnic minority population. These findings may concern various medical contexts in which issues of ethnic underrepresentation in the health system are relevant, as well as sociological contexts, especially those regarding minority populations and professions.

Disruption of de Novo Adenosine Triphosphate (ATP) Biosynthesis Abolishes Virulence in Cryptococcus neoformans.

PubMed

Blundell, Ross D; Williams, Simon J; Arras, Samantha D M; Chitty, Jessica L; Blake, Kirsten L; Ericsson, Daniel J; Tibrewal, Nidhi; Rohr, Jurgen; Koh, Y Q Andre E; Kappler, Ulrike; Robertson, Avril A B; Butler, Mark S; Cooper, Matthew A; Kobe, Bostjan; Fraser, James A

2016-09-09

Opportunistic fungal pathogens such as Cryptococcus neoformans are a growing cause of morbidity and mortality among immunocompromised populations worldwide. To address the current paucity of antifungal therapeutic agents, further research into fungal-specific drug targets is required. Adenylosuccinate synthetase (AdSS) is a crucial enzyme in the adeosine triphosphate (ATP) biosynthetic pathway, catalyzing the formation of adenylosuccinate from inosine monophosphate and aspartate. We have investigated the potential of this enzyme as an antifungal drug target, finding that loss of function results in adenine auxotrophy in C. neoformans, as well as complete loss of virulence in a murine model. Cryptococcal AdSS was expressed and purified in Escherichia coli and the enzyme's crystal structure determined, the first example of a structure of this enzyme from fungi. Together with enzyme kinetic studies, this structural information enabled comparison of the fungal enzyme with the human orthologue and revealed species-specific differences potentially exploitable via rational drug design. These results validate AdSS as a promising antifungal drug target and lay a foundation for future in silico and in vitro screens for novel antifungal compounds.

Los Hispanos: Problemas y Oportunidades. Resumen de la Actual Situacion Demografica, Economica, Social y Politica de los Hispanos en los Estados Unidos y de las Iniciativas Tomadas por la Fundacion Ford Para Hacer Frente a las Necesidades de esta Poblacion en Aumento y Determinar sus Efectos Sobre la Sociedad Estadounidense. Documento de Trabajo de la Fundacion Ford, No. 436.

ERIC Educational Resources Information Center

Ford Foundation, New York, NY.

The Hispanic population's growing impact on American society has caused the Ford Foundation to explore new Foundation initiatives. The 1980 census revealed 14.6 million Hispanics: 60% Mexican American; 14% Puerto Rican; 6% Cuban, and 20% Other. The Hispanic population in the United States is growing and is characterized by diversity; rapid growth…

Urbanization and its implications for food and farming.

PubMed

Satterthwaite, David; McGranahan, Gordon; Tacoli, Cecilia

2010-09-27

This paper discusses the influences on food and farming of an increasingly urbanized world and a declining ratio of food producers to food consumers. Urbanization has been underpinned by the rapid growth in the world economy and in the proportion of gross world product and of workers in industrial and service enterprises. Globally, agriculture has met the demands from this rapidly growing urban population, including food that is more energy-, land-, water- and greenhouse gas emission-intensive. But hundreds of millions of urban dwellers suffer under-nutrition. So the key issues with regard to agriculture and urbanization are whether the growing and changing demands for agricultural products from growing urban populations can be sustained while at the same time underpinning agricultural prosperity and reducing rural and urban poverty. To this are added the need to reduce greenhouse gas emissions and to build resilience in agriculture and urban development to climate change impacts. The paper gives particular attention to low- and middle-income nations since these have more than three-quarters of the world's urban population and most of its largest cities and these include nations where issues of food security are most pressing.

Dynamics of alewives in Lake Ontario following a mass mortality

USGS Publications Warehouse

O'Gorman, Robert; Schneider, Clifford P.

1986-01-01

The U.S. Fish and Wildlife Service and the New York Department of Environmental Conservation assessed the population of alewives Alosa pseudoharengus in U.S. waters of Lake Ontario during 1976–1982 with bottom trawls. Alewives were abundant in 1976 but a die-off greatly reduced their numbers during the winter of 1976–1977. The population quickly recovered, however, adult abundance increasing nearly sevenfold during 1978–1981. In spring 1981 the bottom population in southern Lake Ontario was estimated to be 5.25 × 109 fish weighing 128,500 t. Estimated average alewife biomass per hectare during 1978–1982 far exceeded the estimates for either Lake Michigan during 1967–1982 or western Lake Huron during 1973–1982. Recruitment of age-II fish to the population was affected by abundance of adults in two ways: (1) the number of yearlings produced was directly related to adult abundance at low population levels but inversely related at high population levels; and (2) survival of yearlings to age II was inversely related to adult abundance. Growth in 1977 was exceptional, leaving a wide, unmistakable band on scales of the previously slow-growing adults. This wide growth zone served as a marker to identify survivors of the 1976–1977 die-off and to show that each year after 1978 a successively larger proportion of survivors was failing to grow in length or to form an annulus (54% in 1979, 96% in 1980, and 100% in 1981). There was no marker on scales of alewives recruited after the die-off, but the apparent age composition of our catches strongly suggested that most of them also failed to grow in 1981.

Improvement of the Processes of Liquid-Phase Epitaxial Growth of Nanoheteroepitaxial Structures

NASA Astrophysics Data System (ADS)

Maronchuk, I. I.; Sanikovich, D. D.; Potapkov, P. V.; Vel‧chenko, A. A.

2018-05-01

We have revealed the shortcomings of equipment and technological approaches in growing nanoheteroepitaxial structures with quantum dots by liquid-phase epitaxy. We have developed and fabricated a new vertical barreltype cassette for growing quantum dots and epitaxial layers of various thicknesses in one technological process. A physico-mathematical simulation has been carried out of the processes of liquid-phase epitaxial growth of quantumdimensional structures with the use of the program product SolidWorks (FlowSimulation program). Analysis has revealed the presence of negative factors influencing the growth process of the above structures. The mathematical model has been optimized, and the equipment has been modernized without additional experiments and measurements. The flow dynamics of the process gas in the reactor at various flow rates has been investigated. A method for tuning the thermal equipment has been developed. The calculated and experimental temperature distributions in the process of growing structures with high reproducibility are in good agreement, which confirms the validity of the modernization made.

Computational Morphometry for Detecting Changes in Brain Structure Due to Development, Aging, Learning, Disease and Evolution

PubMed Central

Mietchen, Daniel; Gaser, Christian

2009-01-01

The brain, like any living tissue, is constantly changing in response to genetic and environmental cues and their interaction, leading to changes in brain function and structure, many of which are now in reach of neuroimaging techniques. Computational morphometry on the basis of Magnetic Resonance (MR) images has become the method of choice for studying macroscopic changes of brain structure across time scales. Thanks to computational advances and sophisticated study designs, both the minimal extent of change necessary for detection and, consequently, the minimal periods over which such changes can be detected have been reduced considerably during the last few years. On the other hand, the growing availability of MR images of more and more diverse brain populations also allows more detailed inferences about brain changes that occur over larger time scales, way beyond the duration of an average research project. On this basis, a whole range of issues concerning the structures and functions of the brain are now becoming addressable, thereby providing ample challenges and opportunities for further contributions from neuroinformatics to our understanding of the brain and how it changes over a lifetime and in the course of evolution. PMID:19707517

A passive mutualistic interaction promotes the evolution of spatial structure within microbial populations.

PubMed

Marchal, Marie; Goldschmidt, Felix; Derksen-Müller, Selina N; Panke, Sven; Ackermann, Martin; Johnson, David R

2017-04-24

While mutualistic interactions between different genotypes are pervasive in nature, their evolutionary origin is not clear. The dilemma is that, for mutualistic interactions to emerge and persist, an investment into the partner genotype must pay off: individuals of a first genotype that invest resources to promote the growth of a second genotype must receive a benefit that is not equally accessible to individuals that do not invest. One way for exclusive benefits to emerge is through spatial structure (i.e., physical barriers to the movement of individuals and resources). Here we propose that organisms can evolve their own spatial structure based on physical attachment between individuals, and we hypothesize that attachment evolves when spatial proximity to members of another species is advantageous. We tested this hypothesis using experimental evolution with combinations of E. coli strains that depend on each other to grow. We found that attachment between cells repeatedly evolved within 8 weeks of evolution and observed that many different types of mutations potentially contributed to increased attachment. We postulate a general principle by which passive beneficial interactions between organisms select for attachment, and attachment then provides spatial structure that could be conducive for the evolution of active mutualistic interactions.

A selfish gene governing pollen-pistil compatibility confers reproductive isolation between maize relatives.

PubMed

Kermicle, Jerry L

2006-01-01

Some populations of maize's closest relatives, the annual teosintes of Mexico, are unreceptive to maize pollen. When present in the pistil (silk and ovary) a number of maize genes discriminate against or exclude pollen not carrying the same allele. An analogous gene Tcb1-s was found in some teosinte populations but not in sympatric or parapatric maize. It was polymorphic among populations of teosinte growing wild, but regularly present in populations growing in intimate association with maize as a weed. Introduction of Tcb1-s into maize substantially to fully restored compatibility with Tcb1-s carrying teosintes. Although Tcb1-s pollen can fertilize tcb1 tcb1 maize, it is at a competitive disadvantage relative to tcb1 pollen. Hence, the influence of Tcb1-s on crossability is bidirectional. In the absence of maize, Tcb1-s can increase in teosinte populations without improving their fitness. In the presence of maize, Tcb1-s appears to have been co-opted to provide reproductive isolation for adaptation to a cultivated habitat.