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Sample records for heterogeneous student population

  1. 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.

  2. Investigating Population Heterogeneity With Factor Mixture Models

    ERIC Educational Resources Information Center

    Lubke, Gitta H.; Muthen, Bengt

    2005-01-01

    Sources of population heterogeneity may or may not be observed. If the sources of heterogeneity are observed (e.g., gender), the sample can be split into groups and the data analyzed with methods for multiple groups. If the sources of population heterogeneity are unobserved, the data can be analyzed with latent class models. Factor mixture models…

  3. Specialization and Bet Hedging in Heterogeneous Populations

    NASA Astrophysics Data System (ADS)

    Rulands, Steffen; Jahn, David; Frey, Erwin

    2014-09-01

    Phenotypic heterogeneity is a strategy commonly used by bacteria to rapidly adapt to changing environmental conditions. Here, we study the interplay between phenotypic heterogeneity and genetic diversity in spatially extended populations. By analyzing the spatiotemporal dynamics, we show that the level of mobility and the type of competition qualitatively influence the persistence of phenotypic heterogeneity. While direct competition generally promotes persistence of phenotypic heterogeneity, specialization dominates in models with indirect competition irrespective of the degree of mobility.

  4. Eradication of infectious diseases in heterogeneous populations

    SciTech Connect

    Travis, C.C.; Lenhart, S.M.

    1987-04-01

    A model is presented of infectious disease in heterogeneous populations, which allows for variable intra- to intergroup contact ratios. The authors give necessary and sufficient conditions for disease eradication by means of vaccination. Smallpox is used as an illustrative example.

  5. Range Expansion of Heterogeneous Populations

    NASA Astrophysics Data System (ADS)

    Reiter, Matthias; Rulands, Steffen; Frey, Erwin

    2014-04-01

    Risk spreading in bacterial populations is generally regarded as a strategy to maximize survival. Here, we study its role during range expansion of a genetically diverse population where growth and motility are two alternative traits. We find that during the initial expansion phase fast-growing cells do have a selective advantage. By contrast, asymptotically, generalists balancing motility and reproduction are evolutionarily most successful. These findings are rationalized by a set of coupled Fisher equations complemented by stochastic simulations.

  6. Scale Reliability Evaluation with Heterogeneous Populations

    ERIC Educational Resources Information Center

    Raykov, Tenko; Marcoulides, George A.

    2015-01-01

    A latent variable modeling approach for scale reliability evaluation in heterogeneous populations is discussed. The method can be used for point and interval estimation of reliability of multicomponent measuring instruments in populations representing mixtures of an unknown number of latent classes or subpopulations. The procedure is helpful also…

  7. Population dynamics on heterogeneous bacterial substrates

    NASA Astrophysics Data System (ADS)

    Mobius, Wolfram; Murray, Andrew W.; Nelson, David R.

    2012-02-01

    How species invade new territories and how these range expansions influence the population's genotypes are important questions in the field of population genetics. The majority of work addressing these questions focuses on homogeneous environments. Much less is known about the population dynamics and population genetics when the environmental conditions are heterogeneous in space. To better understand range expansions in two-dimensional heterogeneous environments, we employ a system of bacteria and bacteriophage, the viruses of bacteria. Thereby, the bacteria constitute the environment in which a population of bacteriophages expands. The spread of phage constitutes itself in lysis of bacteria and thus formation of clear regions on bacterial lawns, called plaques. We study the population dynamics and genetics of the expanding page for various patterns of environments.

  8. Heterogeneity in the muscle satellite cell population

    PubMed Central

    Biressi, Stefano; Rando, Thomas A.

    2010-01-01

    Satellite cells, the adult stem cells responsible for skeletal muscle regeneration, are defined by their location between the basal lamina and the fiber sarcolemma. Increasing evidence suggests that satellite cells represent a heterogeneous population of cells with distinct embryological origin and multiple levels of biochemical and functional diversity. This review focuses on the rich diversity of the satellite cell population based on studies across species. Ultimately, a more complete characterization of the heterogeneity of satellite cells will be essential to understand the functional significance in terms of muscle growth, homeostasis, tissue repair, and aging. PMID:20849971

  9. Improving Academic Achievement of Underachieving Students in a Heterogeneous Classroom.

    ERIC Educational Resources Information Center

    Thurman, Richard; Wolfe, Kenton

    This action research project implemented and evaluated a program to address the academic needs of all students in a heterogeneous classroom. The targeted population consisted of middle school students in a rural western Illinois community. Evidence of academic underachievement was documented by teacher observation, surveys, test scores, and…

  10. Phenotype heterogeneity in cancer cell populations

    NASA Astrophysics Data System (ADS)

    Almeida, Luis; Chisholm, Rebecca; Clairambault, Jean; Escargueil, Alexandre; Lorenzi, Tommaso; Lorz, Alexander; Trélat, Emmanuel

    2016-06-01

    Phenotype heterogeneity in cancer cell populations, be it of genetic, epigenetic or stochastic origin, has been identified as a main source of resistance to drug treatments and a major source of therapeutic failures in cancers. The molecular mechanisms of drug resistance are partly understood at the single cell level (e.g., overexpression of ABC transporters or of detoxication enzymes), but poorly predictable in tumours, where they are hypothesised to rely on heterogeneity at the cell population scale, which is thus the right level to describe cancer growth and optimise its control by therapeutic strategies in the clinic. We review a few results from the biological literature on the subject, and from mathematical models that have been published to predict and control evolution towards drug resistance in cancer cell populations. We propose, based on the latter, optimisation strategies of combined treatments to limit emergence of drug resistance to cytotoxic drugs in cancer cell populations, in the monoclonal situation, which limited as it is still retains consistent features of cell population heterogeneity. The polyclonal situation, that may be understood as "bet hedging" of the tumour, thus protecting itself from different sources of drug insults, may lie beyond such strategies and will need further developments. In the monoclonal situation, we have designed an optimised therapeutic strategy relying on a scheduled combination of cytotoxic and cytostatic treatments that can be adapted to different situations of cancer treatments. Finally, we review arguments for biological theoretical frameworks proposed at different time and development scales, the so-called atavistic model (diachronic view relying on Darwinian genotype selection in the coursof billions of years) and the Waddington-like epigenetic landscape endowed with evolutionary quasi-potential (synchronic view relying on Lamarckian phenotype instruction of a given genome by reversible mechanisms), to

  11. Genetic Heterogeneity in Algerian Human Populations

    PubMed Central

    Deba, Tahria; Calafell, Francesc; Benhamamouch, Soraya; Comas, David

    2015-01-01

    The demographic history of human populations in North Africa has been characterized by complex processes of admixture and isolation that have modeled its current gene pool. Diverse genetic ancestral components with different origins (autochthonous, European, Middle Eastern, and sub-Saharan) and genetic heterogeneity in the region have been described. In this complex genetic landscape, Algeria, the largest country in Africa, has been poorly covered, with most of the studies using a single Algerian sample. In order to evaluate the genetic heterogeneity of Algeria, Y-chromosome, mtDNA and autosomal genome-wide makers have been analyzed in several Berber- and Arab-speaking groups. Our results show that the genetic heterogeneity found in Algeria is not correlated with geography or linguistics, challenging the idea of Berber groups being genetically isolated and Arab groups open to gene flow. In addition, we have found that external sources of gene flow into North Africa have been carried more often by females than males, while the North African autochthonous component is more frequent in paternally transmitted genome regions. Our results highlight the different demographic history revealed by different markers and urge to be cautious when deriving general conclusions from partial genomic information or from single samples as representatives of the total population of a region. PMID:26402429

  12. Defining heterogeneity within bacterial populations via single cell approaches.

    PubMed

    Davis, Kimberly M; Isberg, Ralph R

    2016-08-01

    Bacterial populations are heterogeneous, which in many cases can provide a selective advantage during changes in environmental conditions. In some instances, heterogeneity exists at the genetic level, in which significant allelic variation occurs within a population seeded by a single cell. In other cases, heterogeneity exists due to phenotypic differences within a clonal, genetically identical population. A variety of mechanisms can drive this latter strategy. Stochastic fluctuations can drive differential gene expression, but heterogeneity in gene expression can also be driven by environmental changes sensed by individual cells residing in distinct locales. Utilizing multiple single cell approaches, workers have started to uncover the extent of heterogeneity within bacterial populations. This review will first describe several examples of phenotypic and genetic heterogeneity, and then discuss many single cell approaches that have recently been applied to define heterogeneity within bacterial populations. PMID:27273675

  13. Mortality Rates in a Genetically Heterogeneous Population of Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Brooks, Anne; Lithgow, Gordon J.; Johnson, Thomas E.

    1994-02-01

    Age-specific mortality rates in isogenic populations of the nematode Caenorhabditis elegans increase exponentially throughout life. In genetically heterogeneous populations, age-specific mortality increases exponentially until about 17 days and then remains constant until the last death occurs at about 60 days. This period of constant age-specific mortality results from genetic heterogeneity. Subpopulations differ in mean life-span, but they all exhibit near exponential, albeit different, rates of increase in age-specific mortality. Thus, much of the observed heterogeneity in mortality rates later in life could result from genetic heterogeneity and not from an inherent effect of aging.

  14. International Students: A Vulnerable Student Population

    ERIC Educational Resources Information Center

    Sherry, Mark; Thomas, Peter; Chui, Wing Hong

    2010-01-01

    This study examines the experiences of international students at The University of Toledo, where international students comprise approximately 10% of the student population. It highlights problems international students experience such as adapting to a new culture, English language problems, financial problems and lack of understanding from the…

  15. Habitat heterogeneity favors asexual reproduction in natural populations of grassthrips.

    PubMed

    Lavanchy, Guillaume; Strehler, Marie; Llanos Roman, Maria Noemi; Lessard-Therrien, Malie; Humbert, Jean-Yves; Dumas, Zoé; Jalvingh, Kirsten; Ghali, Karim; Fontcuberta García-Cuenca, Amaranta; Zijlstra, Bart; Arlettaz, Raphaël; Schwander, Tanja

    2016-08-01

    Explaining the overwhelming success of sex among eukaryotes is difficult given the obvious costs of sex relative to asexuality. Different studies have shown that sex can provide benefits in spatially heterogeneous environments under specific conditions, but whether spatial heterogeneity commonly contributes to the maintenance of sex in natural populations remains unknown. We experimentally manipulated habitat heterogeneity for sexual and asexual thrips lineages in natural populations and under seminatural mesocosm conditions by varying the number of hostplants available to these herbivorous insects. Asexual lineages rapidly replaced the sexual ones, independently of the level of habitat heterogeneity in mesocosms. In natural populations, the success of sexual thrips decreased with increasing habitat heterogeneity, with sexual thrips apparently only persisting in certain types of hostplant communities. Our results illustrate how genetic diversity-based mechanisms can favor asexuality instead of sex when sexual lineages co-occur with genetically variable asexual lineages. PMID:27346066

  16. Evolutionary dynamics of social dilemmas in structured heterogeneous populations

    PubMed Central

    Santos, F. C.; Pacheco, J. M.; Lenaerts, Tom

    2006-01-01

    Real populations have been shown to be heterogeneous, in which some individuals have many more contacts than others. This fact contrasts with the traditional homogeneous setting used in studies of evolutionary game dynamics. We incorporate heterogeneity in the population by studying games on graphs, in which the variability in connectivity ranges from single-scale graphs, for which heterogeneity is small and associated degree distributions exhibit a Gaussian tale, to scale-free graphs, for which heterogeneity is large with degree distributions exhibiting a power-law behavior. We study the evolution of cooperation, modeled in terms of the most popular dilemmas of cooperation. We show that, for all dilemmas, increasing heterogeneity favors the emergence of cooperation, such that long-term cooperative behavior easily resists short-term noncooperative behavior. Moreover, we show how cooperation depends on the intricate ties between individuals in scale-free populations. PMID:16484371

  17. Evolutionary dynamics of social dilemmas in structured heterogeneous populations.

    PubMed

    Santos, F C; Pacheco, J M; Lenaerts, Tom

    2006-02-28

    Real populations have been shown to be heterogeneous, in which some individuals have many more contacts than others. This fact contrasts with the traditional homogeneous setting used in studies of evolutionary game dynamics. We incorporate heterogeneity in the population by studying games on graphs, in which the variability in connectivity ranges from single-scale graphs, for which heterogeneity is small and associated degree distributions exhibit a Gaussian tale, to scale-free graphs, for which heterogeneity is large with degree distributions exhibiting a power-law behavior. We study the evolution of cooperation, modeled in terms of the most popular dilemmas of cooperation. We show that, for all dilemmas, increasing heterogeneity favors the emergence of cooperation, such that long-term cooperative behavior easily resists short-term noncooperative behavior. Moreover, we show how cooperation depends on the intricate ties between individuals in scale-free populations. PMID:16484371

  18. DEMOGRAPHIC PROCESSES: POPULATION DYNAMICS IN HETEROGENEOUS LANDSCAPES

    EPA Science Inventory

    Few topics have attracted the attention of ecologists more than fluctuations in the numbers of plants and animals through time and their variation in abundance through space. nderstanding population fluctuations, and thus population conservation, requires understanding the links ...

  19. Involuntary bioaccumulation of environmental pollutants in nonsmoking heterogeneous human population

    SciTech Connect

    Krotoszynski, B.K.; O'Neill, H.J.

    1982-01-01

    Chemical bioaccumulation in nonsmoking heterogeneous human population was determined by a noninvasive expired air technique. Ubiquitous and nonubiquitous environmental pollutants were isolated and identified and the respective distribution and inhalation hazards were evaluated. Attempts were made to isolate and identify the state of health related expired air constituents. The selected 291 environmental pollutants or the total estimated bioaccumulation, were distributed among the heterogenous and homogenous study populations as the constituents of the respective chemical bioaccumulation. The bioaccumulation of the environmental pollutants observed in the heterogenous population, including controls, prediabetics and diabetics, consisted of 176 compounds or 60.5% of the total estimated bioaccumulation. The constituents of this bioaccumulation are termed ubiquitous pollutants because they have accumulated in the heterogenous population as the result of the prolonged body exposures irrespectively of the residence, age, height, weight, sex, occupation, diet and the state of health of the exposed individuals. The major contribution to the bioaccumulation in the heterogenous population arose from 150 hydrocarbons (85.2% of total bioaccumulation) which presents serious exposure health hazards to this population. This is supported by the known toxicity and the possible mutagenic and carcinogenic activity of these hydrocarbons. Such health hazards will augment with the increasing utilization of petroleum products in industry and automobiles. (JMT)

  20. Spreading dynamics on heterogeneous populations: Multitype network approach

    NASA Astrophysics Data System (ADS)

    Vazquez, Alexei

    2006-12-01

    I study the spreading of infectious diseases in heterogeneous populations. The population structure is described by a contact graph where vertices represent agents and edges represent disease transmission channels among them. The population heterogeneity is taken into account by the agent’s subdivision in types and the mixing matrix among them. I introduce a type-network representation for the mixing matrix, allowing an intuitive understanding of the mixing patterns and the calculations. Using an iterative approach I obtain recursive equations for the probability distribution of the outbreak size as a function of time. I demonstrate that the expected outbreak size and its progression in time are determined by the largest eigenvalue of the reproductive number matrix and the characteristic distance between agents on the contact graph. Finally, I discuss the impact of intervention strategies to halt epidemic outbreaks. This work provides both a qualitative understanding and tools to obtain quantitative predictions for the spreading dynamics of heterogeneous populations.

  1. The Adult Student Population.

    ERIC Educational Resources Information Center

    Snyder, Fred A.; Blocker, Clyde E.

    This study is concerned with the following topics on adult student attendance at Harrisburg Area Community College (HACC) during the 1969-70 academic year: student background, reason for attendance, enrollment in programs or courses, academic success, evidence of personal and occupational development. The report is based on the useable…

  2. Modeling Radicalization Phenomena in Heterogeneous Populations.

    PubMed

    Galam, Serge; Javarone, Marco Alberto

    2016-01-01

    The phenomenon of radicalization is investigated within a mixed population composed of core and sensitive subpopulations. The latest includes first to third generation immigrants. Respective ways of life may be partially incompatible. In case of a conflict core agents behave as inflexible about the issue. In contrast, sensitive agents can decide either to live peacefully adjusting their way of life to the core one, or to oppose it with eventually joining violent activities. The interplay dynamics between peaceful and opponent sensitive agents is driven by pairwise interactions. These interactions occur both within the sensitive population and by mixing with core agents. The update process is monitored using a Lotka-Volterra-like Ordinary Differential Equation. Given an initial tiny minority of opponents that coexist with both inflexible and peaceful agents, we investigate implications on the emergence of radicalization. Opponents try to turn peaceful agents to opponents driving radicalization. However, inflexible core agents may step in to bring back opponents to a peaceful choice thus weakening the phenomenon. The required minimum individual core involvement to actually curb radicalization is calculated. It is found to be a function of both the majority or minority status of the sensitive subpopulation with respect to the core subpopulation and the degree of activeness of opponents. The results highlight the instrumental role core agents can have to hinder radicalization within the sensitive subpopulation. Some hints are outlined to favor novel public policies towards social integration. PMID:27166677

  3. Modeling Radicalization Phenomena in Heterogeneous Populations

    PubMed Central

    2016-01-01

    The phenomenon of radicalization is investigated within a mixed population composed of core and sensitive subpopulations. The latest includes first to third generation immigrants. Respective ways of life may be partially incompatible. In case of a conflict core agents behave as inflexible about the issue. In contrast, sensitive agents can decide either to live peacefully adjusting their way of life to the core one, or to oppose it with eventually joining violent activities. The interplay dynamics between peaceful and opponent sensitive agents is driven by pairwise interactions. These interactions occur both within the sensitive population and by mixing with core agents. The update process is monitored using a Lotka-Volterra-like Ordinary Differential Equation. Given an initial tiny minority of opponents that coexist with both inflexible and peaceful agents, we investigate implications on the emergence of radicalization. Opponents try to turn peaceful agents to opponents driving radicalization. However, inflexible core agents may step in to bring back opponents to a peaceful choice thus weakening the phenomenon. The required minimum individual core involvement to actually curb radicalization is calculated. It is found to be a function of both the majority or minority status of the sensitive subpopulation with respect to the core subpopulation and the degree of activeness of opponents. The results highlight the instrumental role core agents can have to hinder radicalization within the sensitive subpopulation. Some hints are outlined to favor novel public policies towards social integration. PMID:27166677

  4. Mitochondrial DNA polymorphism reveals hidden heterogeneity within some Asian populations.

    PubMed Central

    Chakraborty, R

    1990-01-01

    Use of data on mtDNA morph distributions from six Asian populations has shown that the observed number of different mtDNA morphs is too large when compared with the number expected on the basis of the observed gene diversity in the mtDNA genome. This excess number of morphs mainly occurs through an excess of rare morphs, and this discrepancy is more pronounced in a pooled sample of five Asian populations. It is suggested that this discrepancy is probably due to internal heterogeneity in each of the anthropologically defined populations. This analysis demonstrates the utility that population data for a single locus, such as the mtDNA genome, have for detecting hidden heterogeneity in populations, provided that the locus has substantial genetic variability, so that many variant alleles can be detected. PMID:2349953

  5. Evolution of pathogens towards low R0 in heterogeneous populations

    PubMed Central

    Kao, Rowland R.

    2006-01-01

    Maximization of the basic reproduction ratio or R0 is widely believed to drive the emergence of novel pathogens. The presence of exploitable heterogeneities in a population, such as high variance in the number of potentially infectious contacts, increases R0 and thus pathogens that can exploit heterogeneities in the contact structure have an advantage over those that do not. However, exploitation of heterogeneities results in a more rapid depletion of the potentially susceptible neighbourhood for an infected host. Here a simple model of pathogen evolution in a heterogeneous environment is developed and placed in the context of HIV transmission. In this model, it is shown that pathogens may evolve towards lower R0, even if this results in pathogen extinction. For sufficiently high transmissibility, two locally stable strategies exist for an evolving pathogen, one that exploits heterogeneities and results in higher R0, and one that does not, and results in lower R0. While the low R0 strategy is never evolutionarily stable, invading strains with higher R0 will also converge to the low R0 strategy if not sufficiently different from the resident strain. Heterogenous transmission is increasingly recognized as fundamental to epidemiological dynamics and the evolution of pathogens; here, it is shown that the ability to exploit heterogeneity is a strategy that can itself evolve. PMID:16730749

  6. On the spread of epidemics in a closed heterogeneous population

    PubMed Central

    Novozhilov, Artem S

    2008-01-01

    Heterogeneity is an important property of any population experiencing a disease. Here we apply general methods of the theory of heterogeneous populations to the simplest mathematical models in epidemiology. In particular, an SIR (susceptible-infective-removed) model is formulated and analyzed when susceptibility to or infectivity of a particular disease is distributed. It is shown that a heterogeneous model can be reduced to a homogeneous model with a nonlinear transmission function, which is given in explicit form. The widely used power transmission function is deduced from the model with distributed susceptibility and infectivity with the initial gamma-distribution of the disease parameters. Therefore, a mechanistic derivation of the phenomenological model, which is believed to mimic reality with high accuracy, is provided. The equation for the final size of an epidemic for an arbitrary initial distribution of susceptibility is found. The implications of population heterogeneity are discussed, in particular, it is pointed out that usual moment-closure methods can lead to erroneous conclusions if applied for the study of the long-term behavior of the models. PMID:18722386

  7. Transcriptional and phenotypical heterogeneity of Trypanosoma cruzi cell populations.

    PubMed

    Seco-Hidalgo, Víctor; De Pablos, Luis Miguel; Osuna, Antonio

    2015-12-01

    Trypanosoma cruzi has a complex life cycle comprising pools of cell populations which circulate among humans, vectors, sylvatic reservoirs and domestic animals. Recent experimental evidence has demonstrated the importance of clonal variations for parasite population dynamics, survival and evolution. By limiting dilution assays, we have isolated seven isogenic clonal cell lines derived from the Pan4 strain of T. cruzi. Applying different molecular techniques, we have been able to provide a comprehensive characterization of the expression heterogeneity in the mucin-associated surface protein (MASP) gene family, where all the clonal isogenic populations were transcriptionally different. Hierarchical cluster analysis and sequence comparison among different MASP cDNA libraries showed that, despite the great variability in MASP expression, some members of the transcriptome (including MASP pseudogenes) are conserved, not only in the life-cycle stages but also among different strains of T. cruzi. Finally, other important aspects for the parasite, such as growth, spontaneous metacyclogenesis or excretion of different catabolites, were also compared among the clones, demonstrating that T. cruzi populations of cells are also phenotypically heterogeneous. Although the evolutionary strategy that sustains the MASP expression polymorphism remains unknown, we suggest that MASP clonal variability and phenotypic heterogeneities found in this study might provide an advantage, allowing a rapid response to environmental pressure or changes during the life cycle of T. cruzi. PMID:26674416

  8. Demographic heterogeneity and the dynamics of open populations.

    PubMed

    Noonburg, Erik G; Chen, Adam; Shima, Jeffrey S; Swearer, Stephen E

    2015-05-01

    Individuals vary in their phenotype and propensity for growth and survival, but the demographic consequences of this remain poorly understood. We extend previous theoretical work on benthic marine populations and formulate a new model to evaluate how demographic heterogeneity among newly settled reef fish affects population stability. We simulated settlement, growth, and mortality of a small reef fish, the common triplefin (Forsterygion lapillurn) in an open "subpopulation" using a delay-differential equation model framework. We modeled demographic heterogeneity with a discrete number of "quality" types, motivated by our previous empirical observations: individuals were either "high quality" (immigrants from nearby subpopulations) or "low quality" (immigrants from distant subpopulations); in our model, quality influences how quickly individuals develop at a given competitor density. Our results demonstrate how demographic heterogeneity and juvenile competition interact to qualitatively alter the effects of settlement on population stability. Specifically, our model suggests that a mixture of quality types can stabilize the equilibrium even when equal settlement of either type alone would result in an unstable equilibrium. These results highlight the importance of among-individual variation in a metapopulation context, and suggest that in systems where dispersal influences individual quality, connectivity may serve to stabilize local populations. PMID:26236830

  9. Transcriptional and phenotypical heterogeneity of Trypanosoma cruzi cell populations

    PubMed Central

    Seco-Hidalgo, Víctor; De Pablos, Luis Miguel; Osuna, Antonio

    2015-01-01

    Trypanosoma cruzi has a complex life cycle comprising pools of cell populations which circulate among humans, vectors, sylvatic reservoirs and domestic animals. Recent experimental evidence has demonstrated the importance of clonal variations for parasite population dynamics, survival and evolution. By limiting dilution assays, we have isolated seven isogenic clonal cell lines derived from the Pan4 strain of T. cruzi. Applying different molecular techniques, we have been able to provide a comprehensive characterization of the expression heterogeneity in the mucin-associated surface protein (MASP) gene family, where all the clonal isogenic populations were transcriptionally different. Hierarchical cluster analysis and sequence comparison among different MASP cDNA libraries showed that, despite the great variability in MASP expression, some members of the transcriptome (including MASP pseudogenes) are conserved, not only in the life-cycle stages but also among different strains of T. cruzi. Finally, other important aspects for the parasite, such as growth, spontaneous metacyclogenesis or excretion of different catabolites, were also compared among the clones, demonstrating that T. cruzi populations of cells are also phenotypically heterogeneous. Although the evolutionary strategy that sustains the MASP expression polymorphism remains unknown, we suggest that MASP clonal variability and phenotypic heterogeneities found in this study might provide an advantage, allowing a rapid response to environmental pressure or changes during the life cycle of T. cruzi. PMID:26674416

  10. Effects of the Heterogeneity of Game Complexity and User Population in Learning Performance of Business Simulation Games

    ERIC Educational Resources Information Center

    Tao, Yu-Hui; Yeh, C. Rosa; Hung, Kung Chin

    2012-01-01

    Previous studies on business simulation games (BSGs) have concluded that improved performance may not be the primary benefit of using BSGs, due to mixed results between student performance and perceptions. Two relevant and insightful issues attract our attention, namely, the impacts of the heterogeneous student population and the different…

  11. Classification method for heterogeneity in monoclonal cell population

    NASA Astrophysics Data System (ADS)

    Aburatani, S.; Tashiro, K.; Kuhara, S.

    2015-09-01

    Monoclonal cell populations are known to be composed of heterogeneous subpopulations, thus complicating the data analysis. To gain clear insights into the mechanisms of cellular systems, biological data from a homogeneous cell population should be obtained. In this study, we developed a method based on Latent Profile Analysis (LPA) combined with Confirmatory Factor Analysis (CFA) to divide mixed data into classes, depending on their heterogeneity. In general cluster analysis, the number of measured points is a constraint, and thereby the data must be classified into fewer groups than the number of samples. By our newly developed method, the measured data can be divided into groups depending on their latent effects, without constraints. Our method is useful to clarify all types of omics data, including transcriptome, proteome and metabolic information.

  12. Signal-to-noise-optimal scaling of heterogenous population codes.

    PubMed

    Leibold, Christian

    2013-01-01

    Similarity measures for neuronal population responses that are based on scalar products can be little informative if the neurons have different firing statistics. Based on signal-to-noise optimality, this paper derives positive weighting factors for the individual neurons' response rates in a heterogeneous neuronal population. The weights only depend on empirical statistics. If firing follows Poisson statistics, the weights can be interpreted as mutual information per spike. The scaling is shown to improve linear separability and clustering as compared to unscaled inputs. PMID:23984844

  13. Assessing Student Attitudes toward Heterogeneous Grouping: A Pilot Study.

    ERIC Educational Resources Information Center

    Poppish, Susan; And Others

    Evidence suggests that tracking of students on the secondary level may not only be discriminatory, but also counterproductive to the personal, educational, and economic potential of all students. The English and Social Studies department of Oak Hill High School, in Wales, Maine, developed an intervention program concerning heterogeneous grouping…

  14. Extreme heterogeneity in populations of vesicular stomatitis virus.

    PubMed Central

    Steinhauer, D A; de la Torre, J C; Meier, E; Holland, J J

    1989-01-01

    Vesicular stomatitis virus (VSV) sequence evolution and population heterogeneity were examined by T1 oligonucleotide mapping. Individual clones isolated from clonal pools of wild-type Indiana serotype VSV displayed identical T1 maps. This was observed even after one passage at high concentrations of the potent viral mutagen 5-fluorouracil. Under low-multiplicity passage conditions, the consensus T1 fingerprint of this virus remained unchanged after 523 passages. Interestingly, however, individual clones from this population (passage 523) differed significantly from each other and from consensus sequence. When virus population equilibria were disrupted by high-multiplicity passage (in which defective interfering particle interference is maximized) or passage in the presence of mutagenic levels of 5-fluorouracil, rapid consensus sequence evolution occurred and extreme population heterogeneity was observed (with some members of these population differing from others at hundreds of genome positions). A limited sampling of clones at one stage during high-multiplicity passages suggested the presence of at least several distinct master sequences, the related subpopulations of which exhibit at least transient competitive fitness within the total virus population (M. Eigen and C.K. Biebricher, p. 211-245, in E. Domingo, J.J. Holland, P. Ahlquist, ed., RNA Genetics, vol. 3, 1988). These studies further demonstrate the important role of selective pressure in determining the genetic composition of RNA virus populations. This is true under equilibrium conditions in which little consensus sequence evolution is observed owing to stabilizing selection as well as under conditions in which selective pressure is driving rapid RNA virus genome evolution. Images PMID:2539503

  15. Identifying and Assessing Interesting Subgroups in a Heterogeneous Population

    PubMed Central

    Lee, Woojoo; Alexeyenko, Andrey; Pernemalm, Maria; Guegan, Justine; Dessen, Philippe; Lazar, Vladimir; Lehtiö, Janne; Pawitan, Yudi

    2015-01-01

    Biological heterogeneity is common in many diseases and it is often the reason for therapeutic failures. Thus, there is great interest in classifying a disease into subtypes that have clinical significance in terms of prognosis or therapy response. One of the most popular methods to uncover unrecognized subtypes is cluster analysis. However, classical clustering methods such as k-means clustering or hierarchical clustering are not guaranteed to produce clinically interesting subtypes. This could be because the main statistical variability—the basis of cluster generation—is dominated by genes not associated with the clinical phenotype of interest. Furthermore, a strong prognostic factor might be relevant for a certain subgroup but not for the whole population; thus an analysis of the whole sample may not reveal this prognostic factor. To address these problems we investigate methods to identify and assess clinically interesting subgroups in a heterogeneous population. The identification step uses a clustering algorithm and to assess significance we use a false discovery rate- (FDR-) based measure. Under the heterogeneity condition the standard FDR estimate is shown to overestimate the true FDR value, but this is remedied by an improved FDR estimation procedure. As illustrations, two real data examples from gene expression studies of lung cancer are provided. PMID:26339613

  16. Student Heterogeneity and Diversity at Catholic Colleges

    ERIC Educational Resources Information Center

    Elliott, Diane Cardenas

    2012-01-01

    The purpose of this study was to examine structural diversity at Catholic colleges; more specifically, the variation in the student body diversity characteristics of a sample of freshman students matriculated at Catholic colleges. For the purpose of this article, diversity characteristics include background characteristics associated with student…

  17. Modeling Heterogeneity in Students Seeking College Counseling

    ERIC Educational Resources Information Center

    Nordberg, Samuel S.

    2013-01-01

    Objective: A series of four studies explored the heuristic value of a method of grouping students in counseling by the severity of symptoms across eight domains. Method: Participants were over 50,000 college students in counseling, assessed with the CCAPS-62 and -34 as part of routine clinical care. Latent Profile Analysis was used to group…

  18. Digital signaling decouples activation probability and population heterogeneity

    PubMed Central

    Kellogg, Ryan A; Tian, Chengzhe; Lipniacki, Tomasz; Quake, Stephen R; Tay, Savaş

    2015-01-01

    Digital signaling enhances robustness of cellular decisions in noisy environments, but it is unclear how digital systems transmit temporal information about a stimulus. To understand how temporal input information is encoded and decoded by the NF-κB system, we studied transcription factor dynamics and gene regulation under dose- and duration-modulated inflammatory inputs. Mathematical modeling predicted and microfluidic single-cell experiments confirmed that integral of the stimulus (or area, concentration × duration) controls the fraction of cells that activate NF-κB in the population. However, stimulus temporal profile determined NF-κB dynamics, cell-to-cell variability, and gene expression phenotype. A sustained, weak stimulation lead to heterogeneous activation and delayed timing that is transmitted to gene expression. In contrast, a transient, strong stimulus with the same area caused rapid and uniform dynamics. These results show that digital NF-κB signaling enables multidimensional control of cellular phenotype via input profile, allowing parallel and independent control of single-cell activation probability and population heterogeneity. DOI: http://dx.doi.org/10.7554/eLife.08931.001 PMID:26488364

  19. Digital signaling decouples activation probability and population heterogeneity.

    PubMed

    Kellogg, Ryan A; Tian, Chengzhe; Lipniacki, Tomasz; Quake, Stephen R; Tay, Savaş

    2015-01-01

    Digital signaling enhances robustness of cellular decisions in noisy environments, but it is unclear how digital systems transmit temporal information about a stimulus. To understand how temporal input information is encoded and decoded by the NF-κB system, we studied transcription factor dynamics and gene regulation under dose- and duration-modulated inflammatory inputs. Mathematical modeling predicted and microfluidic single-cell experiments confirmed that integral of the stimulus (or area, concentration × duration) controls the fraction of cells that activate NF-κB in the population. However, stimulus temporal profile determined NF-κB dynamics, cell-to-cell variability, and gene expression phenotype. A sustained, weak stimulation lead to heterogeneous activation and delayed timing that is transmitted to gene expression. In contrast, a transient, strong stimulus with the same area caused rapid and uniform dynamics. These results show that digital NF-κB signaling enables multidimensional control of cellular phenotype via input profile, allowing parallel and independent control of single-cell activation probability and population heterogeneity. PMID:26488364

  20. Explicit kinetic heterogeneity: mechanistic models for interpretation of labeling data in heterogeneous populations

    SciTech Connect

    Ganusov, Vitaly V

    2008-01-01

    Estimation of division and death rates of lymphocytes in different conditions is vital for quantitative understanding of the immune system. Deuterium, in the form of deuterated glucose or heavy water, can be used to measure rates of proliferation and death of lymphocytes in vivo. Inferring these rates from labeling and delabeling curves has been subject to considerable debate with different groups suggesting different mathematical models for that purpose. We show that the three models that are most commonly used are in fact mathematically identical and differ only in their interpretation of the estimated parameters. By extending these previous models, we here propose a more mechanistic approach for the analysis of data from deuterium labeling experiments. We construct a model of 'kinetic heterogeneity' in which the total cell population consists of many sub-populations with different rates of cell turnover. In this model, for a given distribution of the rates of turnover, the predicted fraction of labeled DNA accumulated and lost can be calculated. Our model reproduces several previously made experimental observations, such as a negative correlation between the length of the labeling period and the rate at which labeled DNA is lost after label cessation. We demonstrate the reliability of the new explicit kinetic heterogeneity model by applying it to artificially generated datasets, and illustrate its usefulness by fitting experimental data. In contrast to previous models, the explicit kinetic heterogeneity model (1) provides a mechanistic way of interpreting labeling data; (2) allows for a non-exponential loss of labeled cells during delabeling, and (3) can be used to describe data with variable labeling length.

  1. Promoting Student Collaboration in a Detracked, Heterogeneous Secondary Mathematics Classroom

    ERIC Educational Resources Information Center

    Staples, Megan E.

    2008-01-01

    Detracking and heterogeneous groupwork are two educational practices that have been shown to have promise for affording all students needed learning opportunities to develop mathematical proficiency. However, teachers face significant pedagogical challenges in organizing productive groupwork in these settings. This study offers an analysis of one…

  2. International Group Heterogeneity and Students' Business Project Achievement

    ERIC Educational Resources Information Center

    Ding, Ning; Bosker, Roel J.; Xu, Xiaoyan; Rugers, Lucie; van Heugten, Petra PAM

    2015-01-01

    In business higher education, group project work plays an essential role. The purpose of the present study is to explore the relationship between the group heterogeneity of students' business project groups and their academic achievements at both group and individual levels. The sample consists of 536 freshmen from an International Business School…

  3. Perturbation theory analysis of competition in a heterogeneous population

    NASA Astrophysics Data System (ADS)

    Utzny, C.; Burroughs, N. J.

    2003-01-01

    A physiologically structured population model of T cell populations at the end of an immune response is proposed and analysed. The proposed model describes a T cell population with a structured death rate mediated by cytokine receptor surface expression. This provides a structuring that determines the ability of a T cell to compete for survival cytokines. Homogeneous differentiation into memory combined with heterogeneous survival abilities leads to a system of nonlinear first-order integro differential equations. The mathematical model is studied analytically by a perturbation approach which agrees well with numerical integrations. We find that the structured death rate leads to selection of T cells expressing high cytokine receptor levels. Selection in this model is independent of the initial T cell distribution which allows us to define a universal selection curve, a property lost under receptor downregulation (i.e. loss of cytokine receptors from the surface). Furthermore, we examine the effects of a population dependent memory differentiation rate and of cytokine receptor downregulation on selection. A population dependent memory differentiation rate increases selection significantly while putting an upper bound on the number of T cells differentiating into memory. Under receptor downregulation a dramatic change of the memory T cell distribution is induced. We find that there exists a critical ratio of the receptor downregulation rate to the average T cell death rate for which selection becomes maximal. Our analysis reveals that this maximum property is the result of an interplay between single cell dynamics and population dynamics. We propose that the selection studied in this paper plays an important role in the selection of optimal T cells for the memory pool.

  4. Detecting Heterogeneity in Population Structure Across the Genome in Admixed Populations.

    PubMed

    McHugh, Caitlin; Brown, Lisa; Thornton, Timothy A

    2016-09-01

    The genetic structure of human populations is often characterized by aggregating measures of ancestry across the autosomal chromosomes. While it may be reasonable to assume that population structure patterns are similar genome-wide in relatively homogeneous populations, this assumption may not be appropriate for admixed populations, such as Hispanics and African-Americans, with recent ancestry from two or more continents. Recent studies have suggested that systematic ancestry differences can arise at genomic locations in admixed populations as a result of selection and nonrandom mating. Here, we propose a method, which we refer to as the chromosomal ancestry differences (CAnD) test, for detecting heterogeneity in population structure across the genome. CAnD can incorporate either local or chromosome-wide ancestry inferred from SNP genotype data to identify chromosomes harboring genomic regions with ancestry contributions that are significantly different than expected. In simulation studies with real genotype data from phase III of the HapMap Project, we demonstrate the validity and power of CAnD. We apply CAnD to the HapMap Mexican-American (MXL) and African-American (ASW) population samples; in this analysis the software RFMix is used to infer local ancestry at genomic regions, assuming admixing from Europeans, West Africans, and Native Americans. The CAnD test provides strong evidence of heterogeneity in population structure across the genome in the MXL sample ([Formula: see text]), which is largely driven by elevated Native American ancestry and deficit of European ancestry on the X chromosomes. Among the ASW, all chromosomes are largely African derived and no heterogeneity in population structure is detected in this sample. PMID:27440868

  5. Population heterogeneity promotes a preference for blind cooperation

    NASA Astrophysics Data System (ADS)

    Perez-Escudero, Alfonso; Friedman, Jonathan; Gore, Jeff

    Game theory--and common sense--recommend to carefully weigh costs and benefits before deciding on a course of action. Yet we often disapprove of people who do so, even when their actual decision benefits us. For example, we prefer people who directly agree to do us a favor over those who agree only after securing enough information to ensure that the favor will not be too costly. Why should we care about how people make their decisions, rather than just focus on the decisions themselves? Hoffman et al. (2015) have shown that such aversion to information gathering may be beneficial when it is strong enough to increase the level of cooperation. Here we show that the same type of aversion arises in heterogeneous populations, but for a different reason: individuals who seek additional information may reveal themselves to be undesirable partners, since they are less likely to cooperate in the future when conditions change. Aversion to information gathering thus facilitates preferential interactions with blind cooperators, who are more favorable partners. Due to this new mechanism the prevalence of such aversion rapidly increases with population diversity, because partner discrimination is more useful in populations which harbor partners of a more varied quality. We gratefully acknowledge funding from the Paul G. Allen Family Foundation, EMBO and Human Frontier Science Program.

  6. Friendship-based partner switching promotes cooperation in heterogeneous populations

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Wu, Te; Li, Zhiwu; Wang, Long

    2016-02-01

    The forming of human social ties tends to be with similar individuals. This study concentrates on the emergence of cooperation among heterogeneous populations. A simple model is proposed by considering the impact of interplay between the evolution of strategies and that of social partnerships on cooperation dynamics. Whenever two individuals acquire the rewards by playing prisoner's dilemma game with each other, the friendship (friendship is quantified as the weight of a link) between the two individuals deepens. Individuals can switch off the social ties with the partners who are unfriendly and rewire to similar new ones. Under this partner switching mechanism, population structure is divided into several groups and cooperation can prevail. It is observed that the frequent tendency of partner switching can lead to the enhancement of cooperative behavior under the enormous temptation to defect. Moreover, the influence of discounting the relationship between different individuals is also investigated. Meanwhile, the cooperation prevails when the adjustment of friendships mainly depends on the incomes of selected individuals rather than that of their partners. Finally, it is found that too similar population fail to maximize the cooperation and there exists a moderate similarity that can optimize cooperation.

  7. Functional heterogeneity of side population cells in skeletal muscle

    SciTech Connect

    Uezumi, Akiyoshi; Ojima, Koichi; Fukada, So-ichiro; Ikemoto, Madoka; Masuda, Satoru; Miyagoe-Suzuki, Yuko; Takeda, Shin'ichi . E-mail: takeda@ncnp.go.jp

    2006-03-17

    Skeletal muscle regeneration has been exclusively attributed to myogenic precursors, satellite cells. A stem cell-rich fraction referred to as side population (SP) cells also resides in skeletal muscle, but its roles in muscle regeneration remain unclear. We found that muscle SP cells could be subdivided into three sub-fractions using CD31 and CD45 markers. The majority of SP cells in normal non-regenerating muscle expressed CD31 and had endothelial characteristics. However, CD31{sup -}CD45{sup -} SP cells, which are a minor subpopulation in normal muscle, actively proliferated upon muscle injury and expressed not only several regulatory genes for muscle regeneration but also some mesenchymal lineage markers. CD31{sup -}CD45{sup -} SP cells showed the greatest myogenic potential among three SP sub-fractions, but indeed revealed mesenchymal potentials in vitro. These SP cells preferentially differentiated into myofibers after intramuscular transplantation in vivo. Our results revealed the heterogeneity of muscle SP cells and suggest that CD31{sup -}CD45{sup -} SP cells participate in muscle regeneration.

  8. 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

  9. 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…

  10. Nonidentifiability of population size from capture-recapture data with heterogeneous detection probabilities

    USGS Publications Warehouse

    Link, W.A.

    2003-01-01

    Heterogeneity in detection probabilities has long been recognized as problematic in mark-recapture studies, and numerous models developed to accommodate its effects. Individual heterogeneity is especially problematic, in that reasonable alternative models may predict essentially identical observations from populations of substantially different sizes. Thus even with very large samples, the analyst will not be able to distinguish among reasonable models of heterogeneity, even though these yield quite distinct inferences about population size. The problem is illustrated with models for closed and open populations.

  11. Breeding site heterogeneity reduces variability in frog recruitment and population dynamics

    USGS Publications Warehouse

    McCaffery, Rebecca M.; Eby, Lisa A.; Maxell, Bryce A.; Corn, Paul Stephen

    2013-01-01

    Environmental stochasticity can have profound effects on the dynamics and viability of wild populations, and habitat heterogeneity provides one mechanism by which populations may be buffered against the negative effects of environmental fluctuations. Heterogeneity in breeding pond hydroperiod across the landscape may allow amphibian populations to persist despite variable interannual precipitation. We examined recruitment dynamics over 10 yr in a high-elevation Columbia spotted frog (Rana luteiventris) population that breeds in ponds with a variety of hydroperiods. We combined these data with matrix population models to quantify the consequences of heterogeneity in pond hydroperiod on net recruitment (i.e. number of metamorphs produced) and population growth rates. We compared our heterogeneous system to hypothetical homogeneous environments with only ephemeral ponds, only semi-permanent ponds, and only permanent ponds. We also examined the effects of breeding pond habitat loss on population growth rates. Most eggs were laid in permanent ponds each year, but survival to metamorphosis was highest in the semi-permanent ponds. Recruitment success varied by both year and pond type. Net recruitment and stochastic population growth rate were highest under a scenario with homogeneous semi-permanent ponds, but variability in recruitment was lowest in the scenario with the observed heterogeneity in hydroperiods. Loss of pond habitat decreased population growth rate, with greater decreases associated with loss of permanent and semi-permanent habitat. The presence of a diversity of pond hydroperiods on the landscape will influence population dynamics, including reducing variability in recruitment in an uncertain climatic future.

  12. Phenotypic heterogeneity is a selected trait in natural yeast populations subject to environmental stress

    PubMed Central

    Holland, Sara L; Reader, Tom; Dyer, Paul S; Avery, Simon V

    2014-01-01

    Populations of genetically uniform microorganisms exhibit phenotypic heterogeneity, where individual cells have varying phenotypes. Such phenotypes include fitness-determining traits. Phenotypic heterogeneity has been linked to increased population-level fitness in laboratory studies, but its adaptive significance for wild microorganisms in the natural environment is unknown. Here, we addressed this by testing heterogeneity in yeast isolates from diverse environmental sites, each polluted with a different principal contaminant, as well as from corresponding control locations. We found that cell-to-cell heterogeneity (in resistance to the appropriate principal pollutant) was prevalent in the wild yeast isolates. Moreover, isolates with the highest heterogeneity were consistently observed in the polluted environments, indicating that heterogeneity is positively related to survival in adverse conditions in the wild. This relationship with survival was stronger than for the property of mean resistance (IC50) of an isolate. Therefore, heterogeneity could be the major determinant of microbial survival in adverse conditions. Indeed, growth assays indicated that isolates with high heterogeneities had a significant competitive advantage during stress. Analysis of yeasts after cultivation for ≥ 500 generations additionally showed that high heterogeneity evolved as a heritable trait during stress. The results showed that environmental stress selects for wild microorganisms with high levels of phenotypic heterogeneity. PMID:24000788

  13. An elaboration of theory about preventing outbreaks in homogeneous populations to include heterogeneity or preferential mixing.

    PubMed

    Feng, Zhilan; Hill, Andrew N; Smith, Philip J; Glasser, John W

    2015-12-01

    The goal of many vaccination programs is to attain the population immunity above which pathogens introduced by infectious people (e.g., travelers from endemic areas) will not cause outbreaks. Using a simple meta-population model, we demonstrate that, if sub-populations either differ in characteristics affecting their basic reproduction numbers or if their members mix preferentially, weighted average sub-population immunities cannot be compared with the proportionally-mixing homogeneous population-immunity threshold, as public health practitioners are wont to do. Then we review the effect of heterogeneity in average per capita contact rates on the basic meta-population reproduction number. To the extent that population density affects contacts, for example, rates might differ in urban and rural sub-populations. Other differences among sub-populations in characteristics affecting their basic reproduction numbers would contribute similarly. In agreement with more recent results, we show that heterogeneous preferential mixing among sub-populations increases the basic meta-population reproduction number more than homogeneous preferential mixing does. Next we refine earlier results on the effects of heterogeneity in sub-population immunities and preferential mixing on the effective meta-population reproduction number. Finally, we propose the vector of partial derivatives of this reproduction number with respect to the sub-population immunities as a fundamentally new tool for targeting vaccination efforts. PMID:26375548

  14. Cell population modelling describes intrinsic heterogeneity: a case study for hematopoietic stem cells.

    PubMed

    Luni, C; Doyle, F J; Elvassore, N

    2011-05-01

    The control of stem cell properties during in vitro expansion is of paramount importance for their clinical use. According to Food and Drug Administration (FDA) guidelines, phenotypic heterogeneity is a critical aspect influencing therapeutic response. Even if the authors ability to reduce heterogeneity were limited, the sources from which it arises should be well understood for safe clinical applications. The aim of this work was to describe theoretically the intrinsic cell population heterogeneity that is present even when cells are cultured in a perfectly homogeneous environment. A bivariate population balance model is developed to account for the heterogeneity in the number of receptors and receptor-ligand complexes per cell, and is coupled with a ligand conservation equation. As a case study, the model is applied to the hematopoietic stem cell expansion, considering the c-Kit receptor and stem cell factor pair. Results show the dependence of intrinsic heterogeneity from ligand concentration and the kinetics of its administration. By tracking the cell generations within the total population, the authors highlight intra- and an inter-generational contributions to total population heterogeneity. In terms of dimensionless variables, intrinsic heterogeneity is dependent on the ratio of the characteristic time of cell division to that needed by a newborn cell to reach its single-cell steady state. [Includes supplementary material]. PMID:21639590

  15. 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.

  16. Herbivore population regulation and resource heterogeneity in a stochastic environment.

    PubMed

    Hempson, G P; Illius, A W; Hendricks, H H; Bond, W J; Vetter, S

    2015-08-01

    Large-mammal herbivore populations are subject to the interaction of internal density-dependent processes and external environmental stochasticity. We disentangle these processes by linking consumer population dynamics, in a highly stochastic environment, to the availability of their key forage resource via effects on body condition and subsequent fecundity and mortality rates. Body condition and demographic rate data were obtained by monitoring 500 tagged female goats in the Richtersveld National Park, South Africa, over a three-year period. Identifying the key resource and pathway to density dependence for a population allows environmental stochasticity to be partitioned into that which has strong feedbacks to population stability, and that which does not. Our data reveal a density- dependent seasonal decline in goat body condition in response to concomitant density-dependent depletion of the dry-season forage resource. The loss in body condition reduced density-dependent pregnancy rates, litter sizes, and pre-weaning survival. Survival was lowest following the most severe dry season and for juveniles. Adult survival in the late-dry season depended on body condition in the mid-dry season. Population growth was determined by the length of the dry season and the population size in the previous year. The RNP goat population is thereby dynamically coupled primarily to its dry-season forage resource. Extreme environmental variability thus does not decouple consumer resource dynamics, in contrast to the views of nonequilibrium protagonists. PMID:26405742

  17. Follow the leader: Herding behavior in heterogeneous populations

    NASA Astrophysics Data System (ADS)

    Mosquera-Doñate, Guillem; Boguñá, Marián

    2015-05-01

    Here we study the emergence of spontaneous collective leadership in large populations. In standard models of opinion dynamics, herding behavior is only obeyed at the local scale due to the interaction of single agents with their neighbors; while at the global scale, such models are governed by purely diffusive processes. Surprisingly, in this paper we show that the combination of a strong separation of time scales within the population and a hierarchical organization of the influences of some agents on the others induces a phase transition between a purely diffusive phase, as in the standard case, and a herding phase where a fraction of the agents self-organize and lead the global opinion of the whole population.

  18. [Antibiotic activity and heterogeneity of a population of Azotobacter chroococcum].

    PubMed

    Pozmogova; Gerasimova, G L; Sadovova, N V; Khovrychev, M P

    1988-01-01

    Antibiotic activity of Azotobacter chroococcum was determined depending on the morphological composition of the population. The population was divided by the sedimentary properties into 2 fractions: heavy (H) and light (L). A higher amount of azochroomycin (up to 170%) could be extracted from the H-fraction consisting mainly of medium size cells (1.3-1.9 nm in diameter) as compared to that from the L-fraction consisting predominantly of the cells of 0.7-1.3 nm in diameter; the activity of the L-fraction counted as 100%. PMID:3290885

  19. An exact procedure for the analysis of heterogeneous kinetics in polyclonal antibody populations.

    PubMed

    Herron, J N; Voss, E W

    1983-11-01

    Antibody populations with heterogeneous binding properties exhibit complex first-order dissociation kinetics. An analytical method has been developed to determine the average dissociation rate constant and the heterogeneity index of a specific antibody population. This procedure was based on Laplace transformation of the gamma distribution function, which yielded an exact, macroscopic rate law for the entire antibody population. Linearization of the macroscopic rate law is achieved by plotting data points versus their numerical derivatives using log-log axes. Linear regression of such plots yields the average dissociation rate constant from the Y-intercept, and heterogeneity index from the slope. This analytic method is transparent to the antibody system and kinetic assay employed, requiring only a programmable calculator to perform the necessary calculations. The usefulness of this analytic method was demonstrated by the evaluation of dissociation kinetics in murine monoclonal and rabbit polyclonal anti-fluorescyl-IgG antibody populations. PMID:6606661

  20. Negative frequency-dependent interactions can underlie phenotypic heterogeneity in a clonal microbial population.

    PubMed

    Healey, David; Axelrod, Kevin; Gore, Jeff

    2016-01-01

    Genetically identical cells in microbial populations often exhibit a remarkable degree of phenotypic heterogeneity even in homogenous environments. Such heterogeneity is commonly thought to represent a bet-hedging strategy against environmental uncertainty. However, evolutionary game theory predicts that phenotypic heterogeneity may also be a response to negative frequency-dependent interactions that favor rare phenotypes over common ones. Here we provide experimental evidence for this alternative explanation in the context of the well-studied yeast GAL network. In an environment containing the two sugars glucose and galactose, the yeast GAL network displays stochastic bimodal activation. We show that in this mixed sugar environment, GAL-ON and GAL-OFF phenotypes can each invade the opposite phenotype when rare and that there exists a resulting stable mix of phenotypes. Consistent with theoretical predictions, the resulting stable mix of phenotypes is not necessarily optimal for population growth. We find that the wild-type mixed strategist GAL network can invade populations of both pure strategists while remaining uninvasible by either. Lastly, using laboratory evolution we show that this mixed resource environment can directly drive the de novo evolution of clonal phenotypic heterogeneity from a pure strategist population. Taken together, our results provide experimental evidence that negative frequency-dependent interactions can underlie the phenotypic heterogeneity found in clonal microbial populations. PMID:27487817

  1. The Impact of Population, Contact, and Spatial Heterogeneity on Epidemic Model Predictions.

    PubMed

    Zagmutt, Francisco J; Schoenbaum, Mark A; Hill, Ashley E

    2016-05-01

    Our objective was to evaluate the effect that complexity in the form of different levels of spatial, population, and contact heterogeneity has in the predictions of a mechanistic epidemic model. A model that simulates the spatiotemporal spread of infectious diseases between animal populations was developed. Sixteen scenarios of foot-and-mouth disease infection in cattle were analyzed, involving combinations of the following factors: multiple production-types (PT) with heterogeneous contact and population structure versus single PT, random versus actual spatial distribution of population units, high versus low infectivity, and no vaccination versus preemptive vaccination. The epidemic size and duration was larger for scenarios with multiple PT versus single PT. Ignoring the actual unit locations did not affect the epidemic size in scenarios with multiple PT/high infectivity, but resulted in smaller epidemic sizes in scenarios using multiple PT/low infectivity. In conclusion, when modeling fast-spreading epidemics, knowing the actual locations of population units may not be as relevant as collecting information on population and contact heterogeneity. In contrast, both population and spatial heterogeneity might be important to model slower spreading epidemic diseases. Our findings can be used to inform data collection and modeling efforts to inform health policy and planning. PMID:26477887

  2. Slow epidemic extinction in populations with heterogeneous infection rates.

    PubMed

    Buono, C; Vazquez, F; Macri, P A; Braunstein, L A

    2013-08-01

    We explore how heterogeneity in the intensity of interactions between people affects epidemic spreading. For that, we study the susceptible-infected-susceptible model on a complex network, where a link connecting individuals i and j is endowed with an infection rate β(ij)=λw(ij) proportional to the intensity of their contact w(ij), with a distribution P(w(ij)) taken from face-to-face experiments analyzed in Cattuto et al. [PLoS ONE 5, e11596 (2010)]. We find an extremely slow decay of the fraction of infected individuals, for a wide range of the control parameter λ. Using a distribution of width a we identify two large regions in the a-λ space with anomalous behaviors, which are reminiscent of rare region effects (Griffiths phases) found in models with quenched disorder. We show that the slow approach to extinction is caused by isolated small groups of highly interacting individuals, which keep epidemics alive for very long times. A mean-field approximation and a percolation approach capture with very good accuracy the absorbing-active transition line for weak (small a) and strong (large a) disorder, respectively. PMID:24032889

  3. Slow epidemic extinction in populations with heterogeneous infection rates

    NASA Astrophysics Data System (ADS)

    Buono, C.; Vazquez, F.; Macri, P. A.; Braunstein, L. A.

    2013-08-01

    We explore how heterogeneity in the intensity of interactions between people affects epidemic spreading. For that, we study the susceptible-infected-susceptible model on a complex network, where a link connecting individuals i and j is endowed with an infection rate βij=λwij proportional to the intensity of their contact wij, with a distribution P(wij) taken from face-to-face experiments analyzed in Cattuto [PLoS ONE1932-620310.1371/journal.pone.0011596 5, e11596 (2010)]. We find an extremely slow decay of the fraction of infected individuals, for a wide range of the control parameter λ. Using a distribution of width a we identify two large regions in the a-λ space with anomalous behaviors, which are reminiscent of rare region effects (Griffiths phases) found in models with quenched disorder. We show that the slow approach to extinction is caused by isolated small groups of highly interacting individuals, which keep epidemics alive for very long times. A mean-field approximation and a percolation approach capture with very good accuracy the absorbing-active transition line for weak (small a) and strong (large a) disorder, respectively.

  4. Modelling Spread of Oncolytic Viruses in Heterogeneous Cell Populations

    NASA Astrophysics Data System (ADS)

    Ellis, Michael; Dobrovolny, Hana

    2014-03-01

    One of the most promising areas in current cancer research and treatment is the use of viruses to attack cancer cells. A number of oncolytic viruses have been identified to date that possess the ability to destroy or neutralize cancer cells while inflicting minimal damage upon healthy cells. Formulation of predictive models that correctly describe the evolution of infected tumor systems is critical to the successful application of oncolytic virus therapy. A number of different models have been proposed for analysis of the oncolytic virus-infected tumor system, with approaches ranging from traditional coupled differential equations such as the Lotka-Volterra predator-prey models, to contemporary modeling frameworks based on neural networks and cellular automata. Existing models are focused on tumor cells and the effects of virus infection, and offer the potential for improvement by including effects upon normal cells. We have recently extended the traditional framework to a 2-cell model addressing the full cellular system including tumor cells, normal cells, and the impacts of viral infection upon both populations. Analysis of the new framework reveals complex interaction between the populations and potential inability to simultaneously eliminate the virus and tumor populations.

  5. Proportional reasoning competence among different student populations

    NASA Astrophysics Data System (ADS)

    Wong, King

    2012-10-01

    A collaborative project between Western Washington University, Rutgers University, and New Mexico State University seeks to understand student's competence level on proportional reasoning. We have been collecting and analyzing data from introductory physics and science education courses using a set of assessment tasks. We utilize the notion of constructs to categorize student thinking according to repetitive patterns. Results suggest that, when students confront ratio and proportion problems, they often experience a gap between the mechanics of the mathematical operations and the conscious understanding of what they are doing. In this poster we will share results of our findings from different courses, institutions, and student populations. Supported by NSF grants DUE-1045227, DUE-1045231, DUE-1045250..

  6. Enabling Privacy-Preserving GWASs in Heterogeneous Human Populations.

    PubMed

    Simmons, Sean; Sahinalp, Cenk; Berger, Bonnie

    2016-07-01

    The proliferation of large genomic databases offers the potential to perform increasingly larger-scale genome-wide association studies (GWASs). Due to privacy concerns, however, access to these data is limited, greatly reducing their usefulness for research. Here, we introduce a computational framework for performing GWASs that adapts principles of differential privacy-a cryptographic theory that facilitates secure analysis of sensitive data-to both protect private phenotype information (e.g., disease status) and correct for population stratification. This framework enables us to produce privacy-preserving GWAS results based on EIGENSTRAT and linear mixed model (LMM)-based statistics, both of which correct for population stratification. We test our differentially private statistics, PrivSTRAT and PrivLMM, on simulated and real GWAS datasets and find they are able to protect privacy while returning meaningful results. Our framework can be used to securely query private genomic datasets to discover which specific genomic alterations may be associated with a disease, thus increasing the availability of these valuable datasets. PMID:27453444

  7. A Mathematical and Computational Approach for Integrating the Major Sources of Cell Population Heterogeneity

    PubMed Central

    Stamatakis, Michail; Zygourakis, Kyriacos

    2010-01-01

    Several approaches have been used in the past to model heterogeneity in bacterial cell populations, with each approach focusing on different source(s) of heterogeneity. However, a holistic approach that integrates all the major sources into a comprehensive framework applicable to cell populations is still lacking. In this work we present the mathematical formulation of a cell population master equation (CPME) that describes cell population dynamics and takes into account the major sources of heterogeneity, namely stochasticity in reaction, DNA-duplication, and division, as well as the random partitioning of species contents into the two daughter cells. The formulation also takes into account cell growth and respects the discrete nature of the molecular contents and cell numbers. We further develop a Monte Carlo algorithm for the simulation of the stochastic processes considered here. To benchmark our new framework, we first use it to quantify the effect of each source of heterogeneity on the intrinsic and the extrinsic phenotypic variability for the well-known two-promoter system used experimentally by Elowitz et al. (2002). We finally apply our framework to a more complicated system and demonstrate how the interplay between noisy gene expression and growth inhibition due to protein accumulation at the single cell level can result in complex behavior at the cell population level. The generality of our framework makes it suitable for studying a vast array of artificial and natural genetic networks. Using our Monte Carlo algorithm, cell population distributions can be predicted for the genetic architecture of interest, thereby quantifying the effect of stochasticity in intracellular reactions or the variability in the rate of physiological processes such as growth and division. Such in silico experiments can give insight into the behavior of cell populations and reveal the major sources contributing to cell population heterogeneity. PMID:20685607

  8. Modelling Lipid Competition Dynamics in Heterogeneous Protocell Populations

    NASA Astrophysics Data System (ADS)

    Shirt-Ediss, Ben; Ruiz-Mirazo, Kepa; Mavelli, Fabio; Solé, Ricard V.

    2014-07-01

    Recent experimental work in the field of synthetic protocell biology has shown that prebiotic vesicles are able to `steal' lipids from each other. This phenomenon is driven purely by asymmetries in the physical state or composition of the vesicle membranes, and, when lipid resource is limited, translates directly into competition amongst the vesicles. Such a scenario is interesting from an origins of life perspective because a rudimentary form of cell-level selection emerges. To sharpen intuition about possible mechanisms underlying this behaviour, experimental work must be complemented with theoretical modelling. The aim of this paper is to provide a coarse-grain mathematical model of protocell lipid competition. Our model is capable of reproducing, often quantitatively, results from core experimental papers that reported distinct types vesicle competition. Additionally, we make some predictions untested in the lab, and develop a general numerical method for quickly solving the equilibrium point of a model vesicle population.

  9. Modelling lipid competition dynamics in heterogeneous protocell populations.

    PubMed

    Shirt-Ediss, Ben; Ruiz-Mirazo, Kepa; Mavelli, Fabio; Solé, Ricard V

    2014-01-01

    Recent experimental work in the field of synthetic protocell biology has shown that prebiotic vesicles are able to 'steal' lipids from each other. This phenomenon is driven purely by asymmetries in the physical state or composition of the vesicle membranes, and, when lipid resource is limited, translates directly into competition amongst the vesicles. Such a scenario is interesting from an origins of life perspective because a rudimentary form of cell-level selection emerges. To sharpen intuition about possible mechanisms underlying this behaviour, experimental work must be complemented with theoretical modelling. The aim of this paper is to provide a coarse-grain mathematical model of protocell lipid competition. Our model is capable of reproducing, often quantitatively, results from core experimental papers that reported distinct types vesicle competition. Additionally, we make some predictions untested in the lab, and develop a general numerical method for quickly solving the equilibrium point of a model vesicle population. PMID:25024020

  10. Modelling Lipid Competition Dynamics in Heterogeneous Protocell Populations

    PubMed Central

    Shirt-Ediss, Ben; Ruiz-Mirazo, Kepa; Mavelli, Fabio; Solé, Ricard V.

    2014-01-01

    Recent experimental work in the field of synthetic protocell biology has shown that prebiotic vesicles are able to ‘steal’ lipids from each other. This phenomenon is driven purely by asymmetries in the physical state or composition of the vesicle membranes, and, when lipid resource is limited, translates directly into competition amongst the vesicles. Such a scenario is interesting from an origins of life perspective because a rudimentary form of cell-level selection emerges. To sharpen intuition about possible mechanisms underlying this behaviour, experimental work must be complemented with theoretical modelling. The aim of this paper is to provide a coarse-grain mathematical model of protocell lipid competition. Our model is capable of reproducing, often quantitatively, results from core experimental papers that reported distinct types vesicle competition. Additionally, we make some predictions untested in the lab, and develop a general numerical method for quickly solving the equilibrium point of a model vesicle population. PMID:25024020

  11. Gene Expression Variability Underlies Adaptive Resistance in Phenotypically Heterogeneous Bacterial Populations.

    PubMed

    Erickson, Keesha E; Otoupal, Peter B; Chatterjee, Anushree

    2015-11-13

    The root cause of the antibiotic resistance crisis is the ability of bacteria to evolve resistance to a multitude of antibiotics and other environmental toxins. The regulation of adaptation is difficult to pinpoint due to extensive phenotypic heterogeneity arising during evolution. Here, we investigate the mechanisms underlying general bacterial adaptation by evolving wild-type Escherichia coli populations to dissimilar chemical toxins. We demonstrate the presence of extensive inter- and intrapopulation phenotypic heterogeneity across adapted populations in multiple traits, including minimum inhibitory concentration, growth rate, and lag time. To search for a common response across the heterogeneous adapted populations, we measured gene expression in three stress-response networks: the mar regulon, the general stress response, and the SOS response. While few genes were differentially expressed, clustering revealed that interpopulation gene expression variability in adapted populations was distinct from that of unadapted populations. Notably, we observed both increases and decreases in gene expression variability upon adaptation. Sequencing select genes revealed that the observed gene expression trends are not necessarily attributable to genetic changes. To further explore the connection between gene expression variability and adaptation, we propagated single-gene knockout and CRISPR (clustered regularly interspaced short palindromic repeats) interference strains and quantified impact on adaptation to antibiotics. We identified significant correlations that suggest genes with low expression variability have greater impact on adaptation. This study provides evidence that gene expression variability can be used as an indicator of bacterial adaptive resistance, even in the face of the pervasive phenotypic heterogeneity underlying adaptation. PMID:27623410

  12. Middle School Math Students' Reactions to Heterogeneous Small Group Work: They Like It!

    ERIC Educational Resources Information Center

    Farivar, Sydney

    Change over time in the cross-achievement level regard of seventh-grade students for teammates in small heterogeneous cooperative learning groups was studied for 184 middle school students (55 percent Hispanic Americans, 27 percent Whites, 14 percent Blacks, and 3 percent Asian Americans) in Los Angeles County (California). Student perceptions…

  13. Basal p21 controls population heterogeneity in cycling and quiescent cell cycle states

    PubMed Central

    Overton, K. Wesley; Spencer, Sabrina L.; Noderer, William L.; Meyer, Tobias; Wang, Clifford L.

    2014-01-01

    Phenotypic heterogeneity within a population of genetically identical cells is emerging as a common theme in multiple biological systems, including human cell biology and cancer. Using live-cell imaging, flow cytometry, and kinetic modeling, we showed that two states—quiescence and cell cycling—can coexist within an isogenic population of human cells and resulted from low basal expression levels of p21, a Cyclin-dependent kinase (CDK) inhibitor (CKI). We attribute the p21-dependent heterogeneity in cell cycle activity to double-negative feedback regulation involving CDK2, p21, and E3 ubiquitin ligases. In support of this mechanism, analysis of cells at a point before cell cycle entry (i.e., before the G1/S transition) revealed a p21–CDK2 axis that determines quiescent and cycling cell states. Our findings suggest a mechanistic role for p21 in generating heterogeneity in both normal tissues and tumors. PMID:25267623

  14. Anomalous diffusion of heterogeneous populations characterized by normal diffusion at the individual level

    PubMed Central

    Hapca, Simona; Crawford, John W; Young, Iain M

    2008-01-01

    The characterization of the dispersal of populations of non-identical individuals is relevant to most ecological and epidemiological processes. In practice, the movement is quantified by observing relatively few individuals, and averaging to estimate the rate of dispersal of the population as a whole. Here, we show that this can lead to serious errors in the predicted movement of the population if the individuals disperse at different rates. We develop a stochastic model for the diffusion of heterogeneous populations, inspired by the movement of the parasitic nematode Phasmarhabditis hermaphrodita. Direct observations of this nematode in homogeneous and heterogeneous environments reveal a large variation in individual behaviour within the population as reflected initially in the speed of the movement. Further statistical analysis shows that the movement is characterized by temporal correlations and in a heterogeneously structured environment the correlations that occur are of shorter range compared with those in a homogeneous environment. Therefore, by using the first-order correlated random walk techniques, we derive an effective diffusion coefficient for each individual, and show that there is a significant variation in this parameter among the population that follows a gamma distribution. Based on these findings, we build a new dispersal model in which we maintain the classical assumption that individual movement can be described by normal diffusion, but due to the variability in individual dispersal rates, the diffusion coefficient is not constant at the population level and follows a continuous distribution. The conclusions and methodology presented are relevant to any heterogeneous population of individuals with widely different diffusion rates. PMID:18708322

  15. The Effect of Population Heterogeneity on Statistical Power in the Design and Evaluation of Interventions

    ERIC Educational Resources Information Center

    Jiang, Depeng; Pepler, Debra; Yao, Hongxing

    2010-01-01

    Do interventions work and for whom? For this article, we examined the influence of population heterogeneity on power in designing and evaluating interventions. On the basis of Monte Carlo simulations in Study 1, we demonstrated that the power to detect the overall intervention effect is lower for a mixture of two subpopulations than for a…

  16. Hypervariable purine biosynthesis genes contribute to stress response population heterogeneity in Campylobacter jejuni

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Population heterogeneity gives bacteria a remarkable ability to survive and grow in swiftly changing environments because the generation of cells with variable phenotypes ensures that some will be successful in hostile conditions. Although pure laboratory cultures have historically been assumed to b...

  17. A score-type test for heterogeneity in zero-inflated models in a stratified population.

    PubMed

    Cao, Guanqun; Hsu, Wei-Wen; Todem, David

    2014-05-30

    We propose a score-type statistic to evaluate heterogeneity in zero-inflated models for count data in a stratified population, where heterogeneity is defined as instances in which the zero counts are generated from two sources. Evaluating heterogeneity in this class of models has attracted considerable attention in the literature, but existing testing procedures have primarily relied on the constancy assumption under the alternative hypothesis. In this paper, we extend the literature by describing a score-type test to evaluate homogeneity against general alternatives that do not neglect the stratification information under the alternative hypothesis. The limiting null distribution of the proposed test statistic is a mixture of chi-squared distributions that can be well approximated by a simple parametric bootstrap procedure. Our numerical simulation studies show that the proposed test can greatly improve efficiency over tests of heterogeneity that ignore the stratification information. An empirical application to dental caries data in early childhood further shows the importance and practical utility of the methodology in using the stratification profile to detect heterogeneity in the population. PMID:24488881

  18. Effect of population heterogenization on the reproducibility of mouse behavior: a multi-laboratory study.

    PubMed

    Richter, S Helene; Garner, Joseph P; Zipser, Benjamin; Lewejohann, Lars; Sachser, Norbert; Touma, Chadi; Schindler, Britta; Chourbaji, Sabine; Brandwein, Christiane; Gass, Peter; van Stipdonk, Niek; van der Harst, Johanneke; Spruijt, Berry; Võikar, Vootele; Wolfer, David P; Würbel, Hanno

    2011-01-01

    In animal experiments, animals, husbandry and test procedures are traditionally standardized to maximize test sensitivity and minimize animal use, assuming that this will also guarantee reproducibility. However, by reducing within-experiment variation, standardization may limit inference to the specific experimental conditions. Indeed, we have recently shown in mice that standardization may generate spurious results in behavioral tests, accounting for poor reproducibility, and that this can be avoided by population heterogenization through systematic variation of experimental conditions. Here, we examined whether a simple form of heterogenization effectively improves reproducibility of test results in a multi-laboratory situation. Each of six laboratories independently ordered 64 female mice of two inbred strains (C57BL/6NCrl, DBA/2NCrl) and examined them for strain differences in five commonly used behavioral tests under two different experimental designs. In the standardized design, experimental conditions were standardized as much as possible in each laboratory, while they were systematically varied with respect to the animals' test age and cage enrichment in the heterogenized design. Although heterogenization tended to improve reproducibility by increasing within-experiment variation relative to between-experiment variation, the effect was too weak to account for the large variation between laboratories. However, our findings confirm the potential of systematic heterogenization for improving reproducibility of animal experiments and highlight the need for effective and practicable heterogenization strategies. PMID:21305027

  19. Effect of Population Heterogenization on the Reproducibility of Mouse Behavior: A Multi-Laboratory Study

    PubMed Central

    Richter, S. Helene; Garner, Joseph P.; Zipser, Benjamin; Lewejohann, Lars; Sachser, Norbert; Touma, Chadi; Schindler, Britta; Chourbaji, Sabine; Brandwein, Christiane; Gass, Peter; van Stipdonk, Niek; van der Harst, Johanneke; Spruijt, Berry; Võikar, Vootele; Wolfer, David P.; Würbel, Hanno

    2011-01-01

    In animal experiments, animals, husbandry and test procedures are traditionally standardized to maximize test sensitivity and minimize animal use, assuming that this will also guarantee reproducibility. However, by reducing within-experiment variation, standardization may limit inference to the specific experimental conditions. Indeed, we have recently shown in mice that standardization may generate spurious results in behavioral tests, accounting for poor reproducibility, and that this can be avoided by population heterogenization through systematic variation of experimental conditions. Here, we examined whether a simple form of heterogenization effectively improves reproducibility of test results in a multi-laboratory situation. Each of six laboratories independently ordered 64 female mice of two inbred strains (C57BL/6NCrl, DBA/2NCrl) and examined them for strain differences in five commonly used behavioral tests under two different experimental designs. In the standardized design, experimental conditions were standardized as much as possible in each laboratory, while they were systematically varied with respect to the animals' test age and cage enrichment in the heterogenized design. Although heterogenization tended to improve reproducibility by increasing within-experiment variation relative to between-experiment variation, the effect was too weak to account for the large variation between laboratories. However, our findings confirm the potential of systematic heterogenization for improving reproducibility of animal experiments and highlight the need for effective and practicable heterogenization strategies. PMID:21305027

  20. Computing an NPMLE for a mixing distribution in two closed heterogeneous population size models.

    PubMed

    Mao, Chang Xuan

    2008-12-01

    Binomial and geometric mixtures can be used to model data gathered in capture-recapture surveys of animal populations, removal surveys of harvest populations, registrations of disease populations, ecological species census, and so on. To compute a nonparametric maximum likelihood estimator for the mixing distribution of heterogeneous capture probabilities, we consider a conditional approach and use a reliable and fast integrative procedure which combines the EM algorithm to increase the likelihood and the vertex-exchange method to update the number of support points. A convergent Newtonian algorithm is used in the M-step of the EM algorithm. PMID:18821726

  1. Distinct allelic patterns of nanog expression impart embryonic stem cell population heterogeneity.

    PubMed

    Wu, Jincheng; Tzanakakis, Emmanuel S

    2013-01-01

    Nanog is a principal pluripotency regulator exhibiting a disperse distribution within stem cell populations in vivo and in vitro. Increasing evidence points to a functional role of Nanog heterogeneity on stem cell fate decisions. Allelic control of Nanog gene expression was reported recently in mouse embryonic stem cells. To better understand how this mode of regulation influences the observed heterogeneity of NANOG in stem cell populations, we assembled a multiscale stochastic population balance equation framework. In addition to allelic control, gene expression noise and random partitioning at cell division were considered. As a result of allelic Nanog expression, the distribution of Nanog exhibited three distinct states but when combined with transcriptional noise the profile became bimodal. Regardless of their allelic expression pattern, initially uniform populations of stem cells gave rise to the same Nanog heterogeneity within ten cell cycles. Depletion of NANOG content in cells switching off both gene alleles was slower than the accumulation of intracellular NANOG after cells turned on at least one of their Nanog gene copies pointing to Nanog state-dependent dynamics. Allelic transcription of Nanog also raises issues regarding the use of stem cell lines with reporter genes knocked in a single allelic locus. Indeed, significant divergence was observed in the reporter and native protein profiles depending on the difference in their half-lives and insertion of the reporter gene in one or both alleles. In stem cell populations with restricted Nanog expression, allelic regulation facilitates the maintenance of fractions of self-renewing cells with sufficient Nanog content to prevent aberrant loss of pluripotency. Our findings underline the role of allelic control of Nanog expression as a prime determinant of stem cell population heterogeneity and warrant further investigation in the contexts of stem cell specification and cell reprogramming. PMID:23874182

  2. Extreme Heterogeneity in Parasitism Despite Low Population Genetic Structure among Monarch Butterflies Inhabiting the Hawaiian Islands

    PubMed Central

    Pierce, Amanda A.; de Roode, Jacobus C.; Altizer, Sonia; Bartel, Rebecca A.

    2014-01-01

    Host movement and spatial structure can strongly influence the ecology and evolution of infectious diseases, with limited host movement potentially leading to high spatial heterogeneity in infection. Monarch butterflies (Danaus plexippus) are best known for undertaking a spectacular long-distance migration in eastern North America; however, they also form non-migratory populations that breed year-round in milder climates such as Hawaii and other tropical locations. Prior work showed an inverse relationship between monarch migratory propensity and the prevalence of the protozoan parasite, Ophryocystis elektroscirrha. Here, we sampled monarchs from replicate sites within each of four Hawaiian Islands to ask whether these populations show consistently high prevalence of the protozoan parasite as seen for monarchs from several other non-migratory populations. Counter to our predictions, we observed striking spatial heterogeneity in parasite prevalence, with infection rates per site ranging from 4–85%. We next used microsatellite markers to ask whether the observed variation in infection might be explained by limited host movement and spatial sub-structuring among sites. Our results showed that monarchs across the Hawaiian Islands form one admixed population, supporting high gene flow among sites. Moreover, measures of individual-level genetic diversity did not predict host infection status, as might be expected if more inbred hosts harbored higher parasite loads. These results suggest that other factors such as landscape-level environmental variation or colonization-extinction processes might instead cause the extreme heterogeneity in monarch butterfly infection observed here. PMID:24926796

  3. Extreme heterogeneity in parasitism despite low population genetic structure among monarch butterflies inhabiting the Hawaiian Islands.

    PubMed

    Pierce, Amanda A; de Roode, Jacobus C; Altizer, Sonia; Bartel, Rebecca A

    2014-01-01

    Host movement and spatial structure can strongly influence the ecology and evolution of infectious diseases, with limited host movement potentially leading to high spatial heterogeneity in infection. Monarch butterflies (Danaus plexippus) are best known for undertaking a spectacular long-distance migration in eastern North America; however, they also form non-migratory populations that breed year-round in milder climates such as Hawaii and other tropical locations. Prior work showed an inverse relationship between monarch migratory propensity and the prevalence of the protozoan parasite, Ophryocystis elektroscirrha. Here, we sampled monarchs from replicate sites within each of four Hawaiian Islands to ask whether these populations show consistently high prevalence of the protozoan parasite as seen for monarchs from several other non-migratory populations. Counter to our predictions, we observed striking spatial heterogeneity in parasite prevalence, with infection rates per site ranging from 4-85%. We next used microsatellite markers to ask whether the observed variation in infection might be explained by limited host movement and spatial sub-structuring among sites. Our results showed that monarchs across the Hawaiian Islands form one admixed population, supporting high gene flow among sites. Moreover, measures of individual-level genetic diversity did not predict host infection status, as might be expected if more inbred hosts harbored higher parasite loads. These results suggest that other factors such as landscape-level environmental variation or colonization-extinction processes might instead cause the extreme heterogeneity in monarch butterfly infection observed here. PMID:24926796

  4. Spatially heterogeneous populations with mixed negative and positive local density dependence.

    PubMed

    Knipl, Diána; Röst, Gergely

    2016-06-01

    Identifying the steady states of a population is a key issue in theoretical ecology, that includes the study of spatially heterogeneous populations. There are several examples of real ecosystems in patchy environments where the habitats are heterogeneous in their local density dependence. We investigate a multi-patch model of a single species with spatial dispersal, where the growth of the local population is logistic in some localities (negative density dependence) while other patches exhibit a strong Allee effect (positive density dependence). When the local dynamics is logistic in each patch and the habitats are interconnected by dispersal then the total population has only the extinction steady state and a componentwise positive equilibrium, corresponding to persistence in each patch. We show that animal populations in patchy environments can have a large number of steady states if local density dependence varies over the locations. It is demonstrated that, depending on the network topology of migration routes between the patches, the interaction of spatial dispersal and local density dependence can create a variety of coexisting stable positive equilibria. We give a detailed description of the multiple ways dispersal can rescue local populations from extinction. PMID:26801607

  5. FIGG: Simulating populations of whole genome sequences for heterogeneous data analyses

    PubMed Central

    2014-01-01

    Background High-throughput sequencing has become one of the primary tools for investigation of the molecular basis of disease. The increasing use of sequencing in investigations that aim to understand both individuals and populations is challenging our ability to develop analysis tools that scale with the data. This issue is of particular concern in studies that exhibit a wide degree of heterogeneity or deviation from the standard reference genome. The advent of population scale sequencing studies requires analysis tools that are developed and tested against matching quantities of heterogeneous data. Results We developed a large-scale whole genome simulation tool, FIGG, which generates large numbers of whole genomes with known sequence characteristics based on direct sampling of experimentally known or theorized variations. For normal variations we used publicly available data to determine the frequency of different mutation classes across the genome. FIGG then uses this information as a background to generate new sequences from a parent sequence with matching frequencies, but different actual mutations. The background can be normal variations, known disease variations, or a theoretical frequency distribution of variations. Conclusion In order to enable the creation of large numbers of genomes, FIGG generates simulated sequences from known genomic variation and iteratively mutates each genome separately. The result is multiple whole genome sequences with unique variations that can primarily be used to provide different reference genomes, model heterogeneous populations, and can offer a standard test environment for new analysis algorithms or bioinformatics tools. PMID:24885193

  6. Single-cell Migration Chip for Chemotaxis-based Microfluidic Selection of Heterogeneous Cell Populations

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Chih; Allen, Steven G.; Ingram, Patrick N.; Buckanovich, Ronald; Merajver, Sofia D.; Yoon, Euisik

    2015-05-01

    Tumor cell migration toward and intravasation into capillaries is an early and key event in cancer metastasis, yet not all cancer cells are imbued with the same capability to do so. This heterogeneity within a tumor is a fundamental property of cancer. Tools to help us understand what molecular characteristics allow a certain subpopulation of cells to spread from the primary tumor are thus critical for overcoming metastasis. Conventional in vitro migration platforms treat populations in aggregate, which leads to a masking of intrinsic differences among cells. Some migration assays reported recently have single-cell resolution, but these platforms do not provide for selective retrieval of the distinct migrating and non-migrating cell populations for further analysis. Thus, to study the intrinsic differences in cells responsible for chemotactic heterogeneity, we developed a single-cell migration platform so that individual cells’ migration behavior can be studied and the heterogeneous population sorted based upon chemotactic phenotype. Furthermore, after migration, the highly chemotactic and non-chemotactic cells were retrieved and proved viable for later molecular analysis of their differences. Moreover, we modified the migration channel to resemble lymphatic capillaries to better understand how certain cancer cells are able to move through geometrically confining spaces.

  7. Using Populism to Engage Students in Critical Thinking

    ERIC Educational Resources Information Center

    Peiser, Andrew

    2013-01-01

    Populism is a relevant issue in the teaching of American history. Historically, the standard interpretation of Populism perceived the movement as favorable. How educators handle conflicting views of Populism is important in engaging students in critical thinking. This article describes the history of American Populism, explains how Populism can be…

  8. Environmental heterogeneity explains the genetic structure of Continental and Mediterranean populations of Fraxinus angustifolia Vahl.

    PubMed

    Temunović, Martina; Franjić, Jozo; Satovic, Zlatko; Grgurev, Marin; Frascaria-Lacoste, Nathalie; Fernández-Manjarrés, Juan F

    2012-01-01

    Tree species with wide distributions often exhibit different levels of genetic structuring correlated to their environment. However, understanding how environmental heterogeneity influences genetic variation is difficult because the effects of gene flow, drift and selection are confounded. We investigated the genetic variation and its ecological correlates in a wind-pollinated Mediterranean tree species, Fraxinus angustifolia Vahl, within a recognised glacial refugium in Croatia. We sampled 11 populations from environmentally divergent habitats within the Continental and Mediterranean biogeographical regions. We combined genetic data analyses based on nuclear microsatellite loci, multivariate statistics on environmental data and ecological niche modelling (ENM). We identified a geographic structure with a high genetic diversity and low differentiation in the Continental region, which contrasted with the significantly lower genetic diversity and higher population divergence in the Mediterranean region. The positive and significant correlation between environmental and genetic distances after controlling for geographic distance suggests an important influence of ecological divergence of the sites in shaping genetic variation. The ENM provided support for niche differentiation between the populations from the Continental and Mediterranean regions, suggesting that contemporary populations may represent two divergent ecotypes. Ecotype differentiation was also supported by multivariate environmental and genetic distance analyses. Our results suggest that despite extensive gene flow in continental areas, long-term stability of heterogeneous environments have likely promoted genetic divergence of ashes in this region and can explain the present-day genetic variation patterns of these ancient populations. PMID:22905171

  9. Environmental Heterogeneity Explains the Genetic Structure of Continental and Mediterranean Populations of Fraxinus angustifolia Vahl

    PubMed Central

    Temunović, Martina; Franjić, Jozo; Satovic, Zlatko; Grgurev, Marin; Frascaria-Lacoste, Nathalie; Fernández-Manjarrés, Juan F.

    2012-01-01

    Tree species with wide distributions often exhibit different levels of genetic structuring correlated to their environment. However, understanding how environmental heterogeneity influences genetic variation is difficult because the effects of gene flow, drift and selection are confounded. We investigated the genetic variation and its ecological correlates in a wind-pollinated Mediterranean tree species, Fraxinus angustifolia Vahl, within a recognised glacial refugium in Croatia. We sampled 11 populations from environmentally divergent habitats within the Continental and Mediterranean biogeographical regions. We combined genetic data analyses based on nuclear microsatellite loci, multivariate statistics on environmental data and ecological niche modelling (ENM). We identified a geographic structure with a high genetic diversity and low differentiation in the Continental region, which contrasted with the significantly lower genetic diversity and higher population divergence in the Mediterranean region. The positive and significant correlation between environmental and genetic distances after controlling for geographic distance suggests an important influence of ecological divergence of the sites in shaping genetic variation. The ENM provided support for niche differentiation between the populations from the Continental and Mediterranean regions, suggesting that contemporary populations may represent two divergent ecotypes. Ecotype differentiation was also supported by multivariate environmental and genetic distance analyses. Our results suggest that despite extensive gene flow in continental areas, long-term stability of heterogeneous environments have likely promoted genetic divergence of ashes in this region and can explain the present-day genetic variation patterns of these ancient populations. PMID:22905171

  10. KIR Genotypic Diversity Can Track Ancestries in Heterogeneous Populations: A Potential Confounder for Disease Association Studies

    PubMed Central

    Singh, Komal Manpreet; Phung, Yume T.; Kohla, Mohamed S.; Lan, Billy Y-A; Chan, Sharon; Suen, Diana L.; Murad, Sahar; Rheault, Shana; Davidson, Peter; Evans, Jennifer; Singh, Manpreet; Dohil, Sofie; Osorio, Robert W.; Wakil, Adil E.; Page, Kimberly; Feng, Sandy; Cooper, Stewart L.

    2014-01-01

    Killer cell immunoglobulin-like receptors (KIR) are encoded by highly polymorphic genes that regulate the activation of natural killer (NK) cells and other lymphocyte subsets, and likely play key roles in innate and adaptive immunity. Association studies increasingly implicate KIR in disease predisposition and outcome but could be confounded by unknown KIR genetic structure in heterogeneous populations. To examine this we characterized the diversity of 16 KIR genes in 712 Northern Californians (NC) stratified by selfassigned ethnicities, and compared the profiles of KIR polymorphism with other US and global populations using a reference database. Sixty-eight distinct KIR genotypes were characterized: 58 in 457 Caucasians (NCC); 17 in 47 African Americans (NCAA); 21 in 80 Asians (NCA); 20 in 74 Hispanics (NCH) and 18 in 54 “other” ethnicities (NCO). KIR genotype patterns and frequencies in the 4 defined ethnicities were compared with each other and with 34 global populations by phylogenetic analysis. Although there were no population-specific genotypes, the KIR genotype frequency patterns faithfully traced the ancestry of NCC, NCAA and NCA but not of NCH whose ancestries are known to be more heterogeneous. KIR genotype frequencies can therefore track ethnic ancestries in modern urban populations. Our data emphasize the importance of selecting ethnically matched controls in KIR based studies to avert spurious associations. PMID:21898189

  11. Polar Fixation of Plasmids during Recombinant Protein Production in Bacillus megaterium Results in Population Heterogeneity.

    PubMed

    Münch, Karin M; Müller, Johannes; Wienecke, Sarah; Bergmann, Simone; Heyber, Steffi; Biedendieck, Rebekka; Münch, Richard; Jahn, Dieter

    2015-09-01

    During the past 2 decades, Bacillus megaterium has been systematically developed for the gram-per-liter scale production of recombinant proteins. The plasmid-based expression systems employed use a xylose-controlled promoter. Protein production analyses at the single-cell level using green fluorescent protein as a model product revealed cell culture heterogeneity characterized by a significant proportion of less productive bacteria. Due to the enormous size of B. megaterium, such bistable behavior seen in subpopulations was readily analyzed by time lapse microscopy and flow cytometry. Cell culture heterogeneity was not caused simply by plasmid loss: instead, an asymmetric distribution of plasmids during cell division was detected during the exponential-growth phase. Multicopy plasmids are generally randomly distributed between daughter cells. However, in vivo and in vitro experiments demonstrated that under conditions of strong protein production, plasmids are retained at one of the cell poles. Furthermore, it was found that cells with accumulated plasmids and high protein production ceased cell division. As a consequence, the overall protein production of the culture was achieved mainly by the subpopulation with a sufficient plasmid copy number. Based on our experimental data, we propose a model whereby the distribution of multicopy plasmids is controlled by polar fixation under protein production conditions. Thereby, cell lines with fluctuating plasmid abundance arise, which results in population heterogeneity. Our results provide initial insights into the mechanism of cellular heterogeneity during plasmid-based recombinant protein production in a Bacillus species. PMID:26116677

  12. Polar Fixation of Plasmids during Recombinant Protein Production in Bacillus megaterium Results in Population Heterogeneity

    PubMed Central

    Münch, Karin M.; Müller, Johannes; Wienecke, Sarah; Bergmann, Simone; Heyber, Steffi; Biedendieck, Rebekka; Jahn, Dieter

    2015-01-01

    During the past 2 decades, Bacillus megaterium has been systematically developed for the gram-per-liter scale production of recombinant proteins. The plasmid-based expression systems employed use a xylose-controlled promoter. Protein production analyses at the single-cell level using green fluorescent protein as a model product revealed cell culture heterogeneity characterized by a significant proportion of less productive bacteria. Due to the enormous size of B. megaterium, such bistable behavior seen in subpopulations was readily analyzed by time lapse microscopy and flow cytometry. Cell culture heterogeneity was not caused simply by plasmid loss: instead, an asymmetric distribution of plasmids during cell division was detected during the exponential-growth phase. Multicopy plasmids are generally randomly distributed between daughter cells. However, in vivo and in vitro experiments demonstrated that under conditions of strong protein production, plasmids are retained at one of the cell poles. Furthermore, it was found that cells with accumulated plasmids and high protein production ceased cell division. As a consequence, the overall protein production of the culture was achieved mainly by the subpopulation with a sufficient plasmid copy number. Based on our experimental data, we propose a model whereby the distribution of multicopy plasmids is controlled by polar fixation under protein production conditions. Thereby, cell lines with fluctuating plasmid abundance arise, which results in population heterogeneity. Our results provide initial insights into the mechanism of cellular heterogeneity during plasmid-based recombinant protein production in a Bacillus species. PMID:26116677

  13. Noise-Driven Phenotypic Heterogeneity with Finite Correlation Time in Clonal Populations

    PubMed Central

    Lee, UnJin; Skinner, John J.; Reinitz, John; Rosner, Marsha Rich; Kim, Eun-Jin

    2015-01-01

    There has been increasing awareness in the wider biological community of the role of clonal phenotypic heterogeneity in playing key roles in phenomena such as cellular bet-hedging and decision making, as in the case of the phage-λ lysis/lysogeny and B. Subtilis competence/vegetative pathways. Here, we report on the effect of stochasticity in growth rate, cellular memory/intermittency, and its relation to phenotypic heterogeneity. We first present a linear stochastic differential model with finite auto-correlation time, where a randomly fluctuating growth rate with a negative average is shown to result in exponential growth for sufficiently large fluctuations in growth rate. We then present a non-linear stochastic self-regulation model where the loss of coherent self-regulation and an increase in noise can induce a shift from bounded to unbounded growth. An important consequence of these models is that while the average change in phenotype may not differ for various parameter sets, the variance of the resulting distributions may considerably change. This demonstrates the necessity of understanding the influence of variance and heterogeneity within seemingly identical clonal populations, while providing a mechanism for varying functional consequences of such heterogeneity. Our results highlight the importance of a paradigm shift from a deterministic to a probabilistic view of clonality in understanding selection as an optimization problem on noise-driven processes, resulting in a wide range of biological implications, from robustness to environmental stress to the development of drug resistance. PMID:26203903

  14. Noise-Driven Phenotypic Heterogeneity with Finite Correlation Time in Clonal Populations.

    PubMed

    Lee, UnJin; Skinner, John J; Reinitz, John; Rosner, Marsha Rich; Kim, Eun-Jin

    2015-01-01

    There has been increasing awareness in the wider biological community of the role of clonal phenotypic heterogeneity in playing key roles in phenomena such as cellular bet-hedging and decision making, as in the case of the phage-λ lysis/lysogeny and B. Subtilis competence/vegetative pathways. Here, we report on the effect of stochasticity in growth rate, cellular memory/intermittency, and its relation to phenotypic heterogeneity. We first present a linear stochastic differential model with finite auto-correlation time, where a randomly fluctuating growth rate with a negative average is shown to result in exponential growth for sufficiently large fluctuations in growth rate. We then present a non-linear stochastic self-regulation model where the loss of coherent self-regulation and an increase in noise can induce a shift from bounded to unbounded growth. An important consequence of these models is that while the average change in phenotype may not differ for various parameter sets, the variance of the resulting distributions may considerably change. This demonstrates the necessity of understanding the influence of variance and heterogeneity within seemingly identical clonal populations, while providing a mechanism for varying functional consequences of such heterogeneity. Our results highlight the importance of a paradigm shift from a deterministic to a probabilistic view of clonality in understanding selection as an optimization problem on noise-driven processes, resulting in a wide range of biological implications, from robustness to environmental stress to the development of drug resistance. PMID:26203903

  15. Heterogeneity and diversity of ABO and Rh blood group genes in select Saudi Arabian populations.

    PubMed

    AlSuhaibani, E S; Kizilbash, N A; Malik, S

    2015-01-01

    In order to investigate the diversity of ABO and Rh blood group genes in the Saudi Arabian population, we assembled the phenotypic data of approximately 66,000 subjects from ten representative Saudi populations: Al-Khobar, Riyadh, Tabuk/Madina Al-Munawaara, Jeddah, Abha, South region, Sakaka, Domah, Al-Qurayat, and Sweer. The frequencies of p[A], q[B], and r[O] alleles at the ABO locus were observed to be 0.1688, 0.1242, and 0.7070, respectively, and the frequency of the D allele at the Rh locus was 0.7138. The heterozygosities at the ABO and Rh loci were 0.4563 and 0.4086, respectively, while the combined heterozygosity was 0.4324. Homogeneity tests revealed the population of Abha to be the most heterogeneous while that of Tabuk/Madina was found to be the least heterogeneous. Homogeneity was higher among the Northern populations while Southern populations demonstrated subdivisions and stratification. Gene diversity analyses yielded a total heterozygosity value of 0.4449. The coefficient of gene differentiation was 0.0090. Nei's genetic distance analyses showed that there was close affinity between the populations of Al-Khobar and Riyadh. The largest differences were observed between the populations of Sakaka and Domah. Furthermore, negative correlations were found between p[A] and r[O] alleles, and between q[B] and r[O] alleles at the ABO locus. Clinal analyses revealed that the r[O] allele showed an increasing trend from North-East to South-West, and conversely the q[B] allele exhibited a decreasing trend at these coordinates. These analyses present interesting aspects of the blood group allele distribution across the geography of Saudi Arabia. PMID:26214466

  16. Landscape heterogeneity drives intra-population niche variation and reproduction in an arctic top predator.

    PubMed

    L'hérault, Vincent; Franke, Alastair; Lecomte, Nicolas; Alogut, Adam; Bêty, Joël

    2013-09-01

    While intra-population variability in resource use is ubiquitous, little is known of how this measure of niche diversity varies in space and its role in population dynamics. Here we examined how heterogeneous breeding environments can structure intra-population niche variation in both resource use and reproductive output. We investigated intra-population niche variation in the Arctic tundra ecosystem, studying peregrine falcon (Falco peregrinus tundrius, White) breeding within a terrestrial-marine gradient near Rankin Inlet, Nunavut, Canada. Using stable isotope analysis, we found that intra-population niches varied at the individual level; we examined within-nest and among-nest variation, though only the latter varied along the terrestrial-marine gradient (i.e., increased among-nest variability among birds nesting within the marine environment, indicating higher degree of specialization). Terrestrial prey species (small herbivores and insectivores) were consumed by virtually all falcons. Falcons nesting within the marine environment made use of marine prey (sea birds), but depended heavily on terrestrial prey (up to 90% of the diet). Using 28-years of peregrine falcon nesting data, we found a positive relationship between the proportion of terrestrial habitat surrounding nest sites and annual nestling production, but no relationship with the likelihood of successfully rearing at least one nestling reaching 25 days old. Annually, successful inland breeders raised 0.47 more young on average compared to offshore breeders, which yields potential fitness consequences for this long-living species. The analyses of niche and reproductive success suggest a potential breeding cost for accessing distant terrestrial prey, perhaps due to additional traveling costs, for those individuals with marine nest site locations. Our study indicates how landscape heterogeneity can generate proximate (niche variation) and ultimate (reproduction) consequences on a population of generalist

  17. Landscape heterogeneity drives intra-population niche variation and reproduction in an arctic top predator

    PubMed Central

    L'Hérault, Vincent; Franke, Alastair; Lecomte, Nicolas; Alogut, Adam; Bêty, Joël

    2013-01-01

    While intra-population variability in resource use is ubiquitous, little is known of how this measure of niche diversity varies in space and its role in population dynamics. Here we examined how heterogeneous breeding environments can structure intra-population niche variation in both resource use and reproductive output. We investigated intra-population niche variation in the Arctic tundra ecosystem, studying peregrine falcon (Falco peregrinus tundrius, White) breeding within a terrestrial-marine gradient near Rankin Inlet, Nunavut, Canada. Using stable isotope analysis, we found that intra-population niches varied at the individual level; we examined within-nest and among-nest variation, though only the latter varied along the terrestrial-marine gradient (i.e., increased among-nest variability among birds nesting within the marine environment, indicating higher degree of specialization). Terrestrial prey species (small herbivores and insectivores) were consumed by virtually all falcons. Falcons nesting within the marine environment made use of marine prey (sea birds), but depended heavily on terrestrial prey (up to 90% of the diet). Using 28-years of peregrine falcon nesting data, we found a positive relationship between the proportion of terrestrial habitat surrounding nest sites and annual nestling production, but no relationship with the likelihood of successfully rearing at least one nestling reaching 25 days old. Annually, successful inland breeders raised 0.47 more young on average compared to offshore breeders, which yields potential fitness consequences for this long-living species. The analyses of niche and reproductive success suggest a potential breeding cost for accessing distant terrestrial prey, perhaps due to additional traveling costs, for those individuals with marine nest site locations. Our study indicates how landscape heterogeneity can generate proximate (niche variation) and ultimate (reproduction) consequences on a population of generalist

  18. Heterogeneous composition of key metabolic gene clusters in a vent mussel symbiont population

    PubMed Central

    Ikuta, Tetsuro; Takaki, Yoshihiro; Nagai, Yukiko; Shimamura, Shigeru; Tsuda, Miwako; Kawagucci, Shinsuke; Aoki, Yui; Inoue, Koji; Teruya, Morimi; Satou, Kazuhito; Teruya, Kuniko; Shimoji, Makiko; Tamotsu, Hinako; Hirano, Takashi; Maruyama, Tadashi; Yoshida, Takao

    2016-01-01

    Chemosynthetic symbiosis is one of the successful systems for adapting to a wide range of habitats including extreme environments, and the metabolic capabilities of symbionts enable host organisms to expand their habitat ranges. However, our understanding of the adaptive strategies that enable symbiotic organisms to expand their habitats is still fragmentary. Here, we report that a single-ribotype endosymbiont population in an individual of the host vent mussel, Bathymodiolus septemdierum has heterogeneous genomes with regard to the composition of key metabolic gene clusters for hydrogen oxidation and nitrate reduction. The host individual harbours heterogeneous symbiont subpopulations that either possess or lack the gene clusters encoding hydrogenase or nitrate reductase. The proportions of the different symbiont subpopulations in a host appeared to vary with the environment or with the host's development. Furthermore, the symbiont subpopulations were distributed in patches to form a mosaic pattern in the gill. Genomic heterogeneity in an endosymbiont population may enable differential utilization of diverse substrates and confer metabolic flexibility. Our findings open a new chapter in our understanding of how symbiotic organisms alter their metabolic capabilities and expand their range of habitats. PMID:26418631

  19. Heterogeneous composition of key metabolic gene clusters in a vent mussel symbiont population.

    PubMed

    Ikuta, Tetsuro; Takaki, Yoshihiro; Nagai, Yukiko; Shimamura, Shigeru; Tsuda, Miwako; Kawagucci, Shinsuke; Aoki, Yui; Inoue, Koji; Teruya, Morimi; Satou, Kazuhito; Teruya, Kuniko; Shimoji, Makiko; Tamotsu, Hinako; Hirano, Takashi; Maruyama, Tadashi; Yoshida, Takao

    2016-04-01

    Chemosynthetic symbiosis is one of the successful systems for adapting to a wide range of habitats including extreme environments, and the metabolic capabilities of symbionts enable host organisms to expand their habitat ranges. However, our understanding of the adaptive strategies that enable symbiotic organisms to expand their habitats is still fragmentary. Here, we report that a single-ribotype endosymbiont population in an individual of the host vent mussel, Bathymodiolus septemdierum has heterogeneous genomes with regard to the composition of key metabolic gene clusters for hydrogen oxidation and nitrate reduction. The host individual harbours heterogeneous symbiont subpopulations that either possess or lack the gene clusters encoding hydrogenase or nitrate reductase. The proportions of the different symbiont subpopulations in a host appeared to vary with the environment or with the host's development. Furthermore, the symbiont subpopulations were distributed in patches to form a mosaic pattern in the gill. Genomic heterogeneity in an endosymbiont population may enable differential utilization of diverse substrates and confer metabolic flexibility. Our findings open a new chapter in our understanding of how symbiotic organisms alter their metabolic capabilities and expand their range of habitats. PMID:26418631

  20. Multiple cell and population-level interactions with mouse embryonic stem cell heterogeneity.

    PubMed

    Cannon, Danielle; Corrigan, Adam M; Miermont, Agnes; McDonel, Patrick; Chubb, Jonathan R

    2015-08-15

    Much of development and disease concerns the generation of gene expression differences between related cells sharing similar niches. However, most analyses of gene expression only assess population and time-averaged levels of steady-state transcription. The mechanisms driving differentiation are buried within snapshots of the average cell, lacking dynamic information and the diverse regulatory history experienced by individual cells. Here, we use a quantitative imaging platform with large time series data sets to determine the regulation of developmental gene expression by cell cycle, lineage, motility and environment. We apply this technology to the regulation of the pluripotency gene Nanog in mouse embryonic stem cells. Our data reveal the diversity of cell and population-level interactions with Nanog dynamics and heterogeneity, and how this regulation responds to triggers of pluripotency. Cell cycles are highly heterogeneous and cycle time increases with Nanog reporter expression, with longer, more variable cycle times as cells approach ground-state pluripotency. Nanog reporter expression is highly stable over multiple cell generations, with fluctuations within cycles confined by an attractor state. Modelling reveals an environmental component to expression stability, in addition to any cell-autonomous behaviour, and we identify interactions of cell density with both cycle behaviour and Nanog. Rex1 expression dynamics showed shared and distinct regulatory effects. Overall, our observations of multiple partially overlapping dynamic heterogeneities imply complex cell and environmental regulation of pluripotent cell behaviour, and suggest simple deterministic views of stem cell states are inappropriate. PMID:26209649

  1. Multiple cell and population-level interactions with mouse embryonic stem cell heterogeneity

    PubMed Central

    Cannon, Danielle; Corrigan, Adam M.; Miermont, Agnes; McDonel, Patrick; Chubb, Jonathan R.

    2015-01-01

    Much of development and disease concerns the generation of gene expression differences between related cells sharing similar niches. However, most analyses of gene expression only assess population and time-averaged levels of steady-state transcription. The mechanisms driving differentiation are buried within snapshots of the average cell, lacking dynamic information and the diverse regulatory history experienced by individual cells. Here, we use a quantitative imaging platform with large time series data sets to determine the regulation of developmental gene expression by cell cycle, lineage, motility and environment. We apply this technology to the regulation of the pluripotency gene Nanog in mouse embryonic stem cells. Our data reveal the diversity of cell and population-level interactions with Nanog dynamics and heterogeneity, and how this regulation responds to triggers of pluripotency. Cell cycles are highly heterogeneous and cycle time increases with Nanog reporter expression, with longer, more variable cycle times as cells approach ground-state pluripotency. Nanog reporter expression is highly stable over multiple cell generations, with fluctuations within cycles confined by an attractor state. Modelling reveals an environmental component to expression stability, in addition to any cell-autonomous behaviour, and we identify interactions of cell density with both cycle behaviour and Nanog. Rex1 expression dynamics showed shared and distinct regulatory effects. Overall, our observations of multiple partially overlapping dynamic heterogeneities imply complex cell and environmental regulation of pluripotent cell behaviour, and suggest simple deterministic views of stem cell states are inappropriate. PMID:26209649

  2. Disease Spread and Its Effect on Population Dynamics in Heterogeneous Environment

    NASA Astrophysics Data System (ADS)

    Upadhyay, Ranjit Kumar; Roy, Parimita

    In this paper, an eco-epidemiological model in which both species diffuse along a spatial gradient has been shown to exhibit temporal chaos at a fixed point in space. The proposed model is a modification of the model recently presented by Upadhyay and Roy [2014]. The spatial interactions among the species have been represented in the form of reaction-diffusion equations. The model incorporates the intrinsic growth rate of fish population which varies linearly with the depth of water. Numerical results show that diffusion can drive otherwise stable system into aperiodic behavior with sensitivity to initial conditions. We show that spatially induced chaos plays an important role in spatial pattern formation in heterogeneous environment. Spatiotemporal distributions of species have been simulated using the diffusivity assumptions realistic for natural eco-epidemic systems. We found that in heterogeneous environment, the temporal dynamics of both the species are drastically different and show chaotic behavior. It was also found that the instability observed in the model is due to spatial heterogeneity and diffusion-driven. Cumulative death rate of predator has an appreciable effect on model dynamics as the spatial distribution of all constituent populations exhibit significant changes when this model parameter is changed and it acts as a regularizing factor.

  3. Bioinformatics and systems biology: bridging the gap between heterogeneous student backgrounds.

    PubMed

    Abeln, Sanne; Molenaar, Douwe; Feenstra, K Anton; Hoefsloot, Huub C J; Teusink, Bas; Heringa, Jaap

    2013-09-01

    Teaching students with very diverse backgrounds can be extremely challenging. This article uses the Bioinformatics and Systems Biology MSc in Amsterdam as a case study to describe how the knowledge gap for students with heterogeneous backgrounds can be bridged. We show that a mix in backgrounds can be turned into an advantage by creating a stimulating learning environment for the students. In the MSc Programme, conversion classes help to bridge differences between students, by mending initial knowledge and skill gaps. Mixing students from different backgrounds in a group to solve a complex task creates an opportunity for the students to reflect on their own abilities. We explain how a truly interdisciplinary approach to teaching helps students of all backgrounds to achieve the MSc end terms. Moreover, transferable skills obtained by the students in such a mixed study environment are invaluable for their later careers. PMID:23603092

  4. Effect of distance-related heterogeneity on population size estimates from point counts

    USGS Publications Warehouse

    Efford, M.G.; Dawson, D.K.

    2009-01-01

    Point counts are used widely to index bird populations. Variation in the proportion of birds counted is a known source of error, and for robust inference it has been advocated that counts be converted to estimates of absolute population size. We used simulation to assess nine methods for the conduct and analysis of point counts when the data included distance-related heterogeneity of individual detection probability. Distance from the observer is a ubiquitous source of heterogeneity, because nearby birds are more easily detected than distant ones. Several recent methods (dependent double-observer, time of first detection, time of detection, independent multiple-observer, and repeated counts) do not account for distance-related heterogeneity, at least in their simpler forms. We assessed bias in estimates of population size by simulating counts with fixed radius w over four time intervals (occasions). Detection probability per occasion was modeled as a half-normal function of distance with scale parameter sigma and intercept g(0) = 1.0. Bias varied with sigma/w; values of sigma inferred from published studies were often 50% for a 100-m fixed-radius count. More critically, the bias of adjusted counts sometimes varied more than that of unadjusted counts, and inference from adjusted counts would be less robust. The problem was not solved by using mixture models or including distance as a covariate. Conventional distance sampling performed well in simulations, but its assumptions are difficult to meet in the field. We conclude that no existing method allows effective estimation of population size from point counts.

  5. Experimentally Verified Parameter Sets for Modelling Heterogeneous Neocortical Pyramidal-Cell Populations

    PubMed Central

    Harrison, Paul M.; Badel, Laurent; Wall, Mark J.; Richardson, Magnus J. E.

    2015-01-01

    Models of neocortical networks are increasingly including the diversity of excitatory and inhibitory neuronal classes. Significant variability in cellular properties are also seen within a nominal neuronal class and this heterogeneity can be expected to influence the population response and information processing in networks. Recent studies have examined the population and network effects of variability in a particular neuronal parameter with some plausibly chosen distribution. However, the empirical variability and covariance seen across multiple parameters are rarely included, partly due to the lack of data on parameter correlations in forms convenient for model construction. To addess this we quantify the heterogeneity within and between the neocortical pyramidal-cell classes in layers 2/3, 4, and the slender-tufted and thick-tufted pyramidal cells of layer 5 using a combination of intracellular recordings, single-neuron modelling and statistical analyses. From the response to both square-pulse and naturalistic fluctuating stimuli, we examined the class-dependent variance and covariance of electrophysiological parameters and identify the role of the h current in generating parameter correlations. A byproduct of the dynamic I-V method we employed is the straightforward extraction of reduced neuron models from experiment. Empirically these models took the refractory exponential integrate-and-fire form and provide an accurate fit to the perisomatic voltage responses of the diverse pyramidal-cell populations when the class-dependent statistics of the model parameters were respected. By quantifying the parameter statistics we obtained an algorithm which generates populations of model neurons, for each of the four pyramidal-cell classes, that adhere to experimentally observed marginal distributions and parameter correlations. As well as providing this tool, which we hope will be of use for exploring the effects of heterogeneity in neocortical networks, we also provide

  6. Cluster detection of diseases in heterogeneous populations: an alternative to scan methods.

    PubMed

    Ramis, Rebeca; Gómez-Barroso, Diana; López-Abente, Gonzalo

    2014-05-01

    Cluster detection has become an important part of the agenda of epidemiologists and public health authorities, the identification of high- and low-risk areas is fundamental in the definition of public health strategies and in the suggestion of potential risks factors. Currently, there are different cluster detection techniques available, the most popular being those using windows to scan the areas within the studied region. However, when these areas are heterogeneous in populations' sizes, scan window methods can lead to inaccurate conclusions. In order to perform cluster detection over heterogeneously populated areas, we developed a method not based on scanning windows but instead on standard mortality ratios (SMR) using irregular spatial aggregation (ISA). Its extension, i.e. irregular spatial aggregation with covariates (ISAC), includes covariates with residuals from Poisson regression. We compared the performance of the method with the flexible shaped spatial scan statistic (FlexScan) using mortality data for stomach and bladder cancer for 8,098 Spanish towns. The results show a collection of clusters for stomach and bladder cancer similar to that detected by ISA and FlexScan. However, in general, clusters detected by FlexScan were bigger and include towns with SMR, which were not statistically significant. For bladder cancer, clusters detected by ISAC differed from those detected by ISA and FlexScan in shape and location. The ISA and ISAC methods could be an alternative to the traditional scan window methods for cluster detection over aggregated data when the areas under study are heterogeneous in terms of population. The simplicity and flexibility of the methods make them more attractive than methods based on more complicated algorithms. PMID:24893029

  7. Restructuring Laboratory Worksheets for Junior High School Biology Students in the Heterogeneous Classroom.

    ERIC Educational Resources Information Center

    Witenoff, Shalamit; Lazarowitz, Reuven

    1993-01-01

    Presents samples of educational material adapted for laboratory use on the subject of the pH scale, dilution skills, and their relevance to biology. The experiments were developed for use in both ninth-grade heterogeneous and tracked classes in biology. Students were assessed for academic achievement in relation to their operational reasoning…

  8. Assessing Heterogeneous Student Bodies Using a Methodology that Encourages the Acquisition of Skills Valued by Employers

    ERIC Educational Resources Information Center

    Perdigones, Alicia; Garcia, Jose Luis; Valino, Vanesa; Raposo, Cecilia

    2009-01-01

    This work compares the results of three assessment systems used in two Spanish universities (the "Universidad Politecnica de Madrid" and the "Universidad Catolica de Avila"): the traditional system based on final examinations, continuous assessment with periodic tests and a proposed system (specially designed for heterogeneous student bodies)…

  9. Power in Numbers: Student Participation in Mathematical Discussions in Heterogeneous Spaces

    ERIC Educational Resources Information Center

    Esmonde, Indigo; Langer-Osuna, Jennifer M.

    2013-01-01

    Mathematics classrooms are conceptualized as heterogeneous spaces in which multiple figured worlds come into contact. The study explores how a group of high school students drew upon several figured worlds as they navigated mathematical discussions. (Contains 5 excerpts and 2 footnotes.)

  10. Ecological Complexity in a Coffee Agroecosystem: Spatial Heterogeneity, Population Persistence and Biological Control

    PubMed Central

    Liere, Heidi; Jackson, Doug; Vandermeer, John

    2012-01-01

    Background Spatial heterogeneity is essential for the persistence of many inherently unstable systems such as predator-prey and parasitoid-host interactions. Since biological interactions themselves can create heterogeneity in space, the heterogeneity necessary for the persistence of an unstable system could be the result of local interactions involving elements of the unstable system itself. Methodology/Principal Findings Here we report on a predatory ladybird beetle whose natural history suggests that the beetle requires the patchy distribution of the mutualism between its prey, the green coffee scale, and the arboreal ant, Azteca instabilis. Based on known ecological interactions and the natural history of the system, we constructed a spatially-explicit model and showed that the clustered spatial pattern of ant nests facilitates the persistence of the beetle populations. Furthermore, we show that the dynamics of the beetle consuming the scale insects can cause the clustered distribution of the mutualistic ants in the first place. Conclusions/Significance From a theoretical point of view, our model represents a novel situation in which a predator indirectly causes a spatial pattern of an organism other than its prey, and in doing so facilitates its own persistence. From a practical point of view, it is noteworthy that one of the elements in the system is a persistent pest of coffee, an important world commodity. This pest, we argue, is kept within limits of control through a complex web of ecological interactions that involves the emergent spatial pattern. PMID:23029061

  11. Characteristics of the General Physics student population.

    NASA Astrophysics Data System (ADS)

    Hunt, Gary L.

    2006-12-01

    Are pre-medical students different than the other students in a General physics class? They often appear to be different, based on how often they seek help from the instructor or how nervous they are about 2 points on a lab report. But are these students different in a measurable characteristic? The purpose of this study is to better understand the characteristics of the students in the introductory physics classes. This is the first step toward improving the instruction. By better understanding the students the classroom, the organization and pedagogy can be adjusted to optimize student learning. The characteristics to be investigated during this study are: · student epistemological structure, · student attitudes, · science course preparation prior to this course, · study techniques used, · physics concepts gained during the class · performance in the class. The data will be analyzed to investigate differences between groups. The groups investigated will be major, gender, and traditional/nontraditional students.

  12. Assessing the Implicit Curriculum in Social Work Education: Heterogeneity of Students' Experiences and Impact on Professional Empowerment

    ERIC Educational Resources Information Center

    Peterson, N. Andrew; Farmer, Antoinette Y.; Donnelly, Louis; Forenza, Brad

    2014-01-01

    The implicit curriculum, which refers to a student's learning environment, has been described as an essential feature of an integrated professional social work curriculum. Very little is known, however, about the heterogeneity of students' experiences with the implicit curriculum, how this heterogeneity may be distributed across groups…

  13. Impact of Roles Assignation on Heterogeneous Populations in Evolutionary Dictator Game

    PubMed Central

    Deng, Xinyang; Liu, Qi; Sadiq, Rehan; Deng, Yong

    2014-01-01

    The evolution of cooperation is a hot and challenging topic in the field of evolutionary game theory. Altruistic behavior, as a particular form of cooperation, has been widely studied by the ultimatum game but not by the dictator game, which provides a more elegant way to identify the altruistic component of behaviors. In this paper, the evolutionary dictator game is applied to model the real motivations of altruism. A degree-based regime is utilized to assess the impact of the assignation of roles on evolutionary outcome in populations of heterogeneous structure with two kinds of strategic updating mechanisms, which are based on Darwin's theory of evolution and punctuated equilibrium, respectively. The results show that the evolutionary outcome is affected by the role assignation and that this impact also depends on the strategic updating mechanisms, the function used to evaluate players' success, and the structure of populations. PMID:25377303

  14. Impact of roles assignation on heterogeneous populations in evolutionary dictator game.

    PubMed

    Deng, Xinyang; Liu, Qi; Sadiq, Rehan; Deng, Yong

    2014-01-01

    The evolution of cooperation is a hot and challenging topic in the field of evolutionary game theory. Altruistic behavior, as a particular form of cooperation, has been widely studied by the ultimatum game but not by the dictator game, which provides a more elegant way to identify the altruistic component of behaviors. In this paper, the evolutionary dictator game is applied to model the real motivations of altruism. A degree-based regime is utilized to assess the impact of the assignation of roles on evolutionary outcome in populations of heterogeneous structure with two kinds of strategic updating mechanisms, which are based on Darwin's theory of evolution and punctuated equilibrium, respectively. The results show that the evolutionary outcome is affected by the role assignation and that this impact also depends on the strategic updating mechanisms, the function used to evaluate players' success, and the structure of populations. PMID:25377303

  15. Molecular crowding causes narrowing of population heterogeneity and restricts internal dynamics in a protein

    NASA Astrophysics Data System (ADS)

    Mondal, Samsuzzoha; Kallianpur, Mamata V.; Udgaonkar, Jayant B.; Krishnamoorthy, G.

    2016-03-01

    Macromolecular crowding is a distinguishing property of intracellular media. Knowledge on the structure and dynamics of a protein in a crowded environment is essential for a complete understanding of its function. Reduction in intermolecular space could cause structural and functional alterations. Here, we have studied a model protein barstar to see how polyethylene glycol (PEG)-induced crowding affects its various structural states (native, unfolded and molten-globule-like) with different extents of change in conformational heterogeneity. Intramolecular distances and distance distributions were determined by time-resolved Förster resonance energy transfer from Trp53 to several acceptor sites by analysis of fluorescence decay kinetics using the Maximum Entropy Method. We observed PEG-induced narrowing of population distributions along with shifting of populations towards more compact states. Structural compactness also resulted in the slowing down of internal dynamics of the protein as revealed by fluorescence anisotropy decay kinetics of the fluorophore IAEDANS attached at several sites.

  16. Impact of Roles Assignation on Heterogeneous Populations in Evolutionary Dictator Game

    NASA Astrophysics Data System (ADS)

    Deng, Xinyang; Liu, Qi; Sadiq, Rehan; Deng, Yong

    2014-11-01

    The evolution of cooperation is a hot and challenging topic in the field of evolutionary game theory. Altruistic behavior, as a particular form of cooperation, has been widely studied by the ultimatum game but not by the dictator game, which provides a more elegant way to identify the altruistic component of behaviors. In this paper, the evolutionary dictator game is applied to model the real motivations of altruism. A degree-based regime is utilized to assess the impact of the assignation of roles on evolutionary outcome in populations of heterogeneous structure with two kinds of strategic updating mechanisms, which are based on Darwin's theory of evolution and punctuated equilibrium, respectively. The results show that the evolutionary outcome is affected by the role assignation and that this impact also depends on the strategic updating mechanisms, the function used to evaluate players' success, and the structure of populations.

  17. Asymptomatic Volunteers with a Polycystic Ovary Are a Functionally Distinct but Heterogeneous Population

    PubMed Central

    Mortensen, Monica; Ehrmann, David A.; Littlejohn, Elizabeth; Rosenfield, Robert L.

    2009-01-01

    Context/Objective: Our objective was to determine the ovarian function of asymptomatic volunteers with a polycystic ovary (V-PCO). Participants: Non-hirsute eumenorrheic V-PCO (n = 32) and volunteers with ultrasonographically normal ovaries (V-NO) (n = 21) were compared with one another and with polycystic ovary syndrome (PCOS) patients who met National Institute of Health criteria (n = 90). Design/Setting/Interventions: GnRH agonist (GnRHag), ACTH, and oral glucose tolerance tests were prospectively performed in a General Clinical Research Center. Results: The distribution of 17-hydroxyprogesterone (17OHP) responses to GnRHag of V-PCO formed a distinct population intermediate between that of V-NO, the reference population, and PCOS. Nevertheless, the V-PCO population was heterogeneous. There were 53% (seventeen of 32) that were functionally normal, with 17OHP responses and free testosterone levels like V-NO. A total of 25% (eight of 32) had an elevated free testosterone, thus meeting Rotterdam criteria for PCOS; one third of these had 17OHP hyperresponsiveness to GnRHag testing. The remaining 22% (seven of 32) had 17OHP hyperresponsiveness to GnRHag, but normal free testosterone. Of PCOS, 69% had elevated 17OHP hyperresponsiveness to GnRHag. Ovarian volume correlated significantly with 17OHP responses only in PCOS, accounting for just 10% of the variance. Conclusions: Many asymptomatic volunteers have a PCO. They are a distinct, but heterogeneous, population with respect to ovarian function, ranging from normal (53%) to occult PCOS by Rotterdam criteria (25%). Nearly one quarter (22%) had the typical PCOS type of ovarian dysfunction without hyperandrogenemia, termed a “dysregulated PCO”; they or their offspring may be at risk for PCOS. Ovarian ultrasonographic characteristics must be considered when establishing norms for ovarian function. PMID:19240158

  18. Licensing by Inflammatory Cytokines Abolishes Heterogeneity of Immunosuppressive Function of Mesenchymal Stem Cell Population.

    PubMed

    Szabó, Enikő; Fajka-Boja, Roberta; Kriston-Pál, Éva; Hornung, Ákos; Makra, Ildikó; Kudlik, Gyöngyi; Uher, Ferenc; Katona, Róbert László; Monostori, Éva; Czibula, Ágnes

    2015-09-15

    When mesenchymal stem cells (MSCs) are used for therapy of immunological pathologies, they get into an inflammatory environment, altering the effectiveness of the treatment. To establish the impact of environmental inflammatory factors on MSCs' immunofunction in the mirror of intrinsic heterogeneity of mouse MSC population, individual MSC clones were generated and characterized. Adipogenic but not osteogenic differentiation and pro-angiogenic activity of five independent MSC cell lines were similar. Regarding osteogenic differentiation, clones MSC3 and MSC6 exhibited poorer capacity than MSC2, MSC4, and MSC5. To study the immunosuppressive heterogeneity, in vitro and in vivo experiments have been carried out using T-cell proliferation assay and delayed-type hypersensitivity (DTH) response, respectively. A remarkable difference was found between the clones in their ability to inhibit T-cell proliferation in the following order: MSC2≥MSC5>MSC4>MSC3 > MSC6. Nevertheless, the differences between the immunosuppressive activities of the individual clones disappeared on pretreatment of the cells with pro-inflammatory cytokines, a procedure called licensing. Stimulation of all clones with IFN-γ and TNF-α resulted in elevation of their inhibitory capability to a similar level. Nitric oxide (NO) and prostaglandin E2 (PGE2) were identified as major mediators of immunofunction of the MSC clones. The earlier findings were also supported by in vivo results. Without licensing, MSC2 inhibited DTH response, while MSC6 did not affect DTH response. In contrast, prestimulation of MSC6 with inflammatory cytokines resulted in strong suppression by this clone as well. Here, we have showed that MSC population is functionally heterogeneous in terms of immunosuppressive function; however, this variability is largely reduced under pro-inflammatory conditions. PMID:26153898

  19. Projection specificity in heterogeneous locus coeruleus cell populations: implications for learning and memory

    PubMed Central

    Uematsu, Akira; Tan, Bao Zhen

    2015-01-01

    Noradrenergic neurons in the locus coeruleus (LC) play a critical role in many functions including learning and memory. This relatively small population of cells sends widespread projections throughout the brain including to a number of regions such as the amygdala which is involved in emotional associative learning and the medial prefrontal cortex which is important for facilitating flexibility when learning rules change. LC noradrenergic cells participate in both of these functions, but it is not clear how this small population of neurons modulates these partially distinct processes. Here we review anatomical, behavioral, and electrophysiological studies to assess how LC noradrenergic neurons regulate these different aspects of learning and memory. Previous work has demonstrated that subpopulations of LC noradrenergic cells innervate specific brain regions suggesting heterogeneity of function in LC neurons. Furthermore, noradrenaline in mPFC and amygdala has distinct effects on emotional learning and cognitive flexibility. Finally, neural recording data show that LC neurons respond during associative learning and when previously learned task contingencies change. Together, these studies suggest a working model in which distinct and potentially opposing subsets of LC neurons modulate particular learning functions through restricted efferent connectivity with amygdala or mPFC. This type of model may provide a general framework for understanding other neuromodulatory systems, which also exhibit cell type heterogeneity and projection specificity. PMID:26330494

  20. The side population of ovarian cancer cells defines a heterogeneous compartment exhibiting stem cell characteristics.

    PubMed

    Boesch, Maximilian; Zeimet, Alain G; Reimer, Daniel; Schmidt, Stefan; Gastl, Guenther; Parson, Walther; Spoeck, Franziska; Hatina, Jiri; Wolf, Dominik; Sopper, Sieghart

    2014-08-30

    Cancer stem cells (CSC) are believed to be involved in tumor evasion of classical antitumor therapies and have thus become an attractive target for further improvement of anticancer strategies. However, the existence and identity of CSC are still a matter of controversy. In a systematic screen of 13 ovarian cancer cell lines we show that cells with stem cell properties are reliably detectable as a minor population, characterized by ABC transporter expression resulting in the side population (SP) phenotype. In different cell lines, either ABCG2 or ABCB1 was found to be responsible for this effect. Purified SP cells featured virtually all characteristics of bona fide CSC, including clonogenicity, asymmetric division and high tumorigenicity in vivo. Using in-depth phenotyping by multicolor flow cytometry, we found that among the investigated ovarian cancer cell lines the SP compartment exhibits tremendous heterogeneity and is composed of multiple phenotypically distinct subpopulations. Thus, our study confirms previous results showing that CSC are contained within the SP. However, the exact identity of the CSC is still disguised by the high complexity of the CSC-containing compartment. Further functional studies are needed to determine whether a single cellular subset can unambiguously be defined as CSC or whether multiple stem cell-like cells with different properties coexist. Moreover, the observed heterogeneity may reflect a high level of plasticity and likely influences tumor progression, escape from immune-surveillance and development of resistance to anticancer therapies and should therefore be considered in the development of new treatment strategies. PMID:25216521

  1. High school students' understanding and problem solving in population genetics

    NASA Astrophysics Data System (ADS)

    Soderberg, Patti D.

    This study is an investigation of student understanding of population genetics and how students developed, used and revised conceptual models to solve problems. The students in this study participated in three rounds of problem solving. The first round involved the use of a population genetics model to predict the number of carriers in a population. The second round required them to revise their model of simple dominance population genetics to make inferences about populations containing three phenotype variations. The third round of problem solving required the students to revise their model of population genetics to explain anomalous data where the proportions of males and females with a trait varied significantly. As the students solved problems, they were involved in basic scientific processes as they observed population phenomena, constructed explanatory models to explain the data they observed, and attempted to persuade their peers as to the adequacy of their models. In this study, the students produced new knowledge about the genetics of a trait in a population through the revision and use of explanatory population genetics models using reasoning that was similar to what scientists do. The students learned, used and revised a model of Hardy-Weinberg equilibrium to generate and test hypotheses about the genetics of phenotypes given only population data. Students were also interviewed prior to and following instruction. This study suggests that a commonly held intuitive belief about the predominance of a dominant variation in populations is resistant to change, despite instruction and interferes with a student's ability to understand Hardy-Weinberg equilibrium and microevolution.

  2. Stochastic multi-scale models of competition within heterogeneous cellular populations: Simulation methods and mean-field analysis.

    PubMed

    Cruz, Roberto de la; Guerrero, Pilar; Spill, Fabian; Alarcón, Tomás

    2016-10-21

    We propose a modelling framework to analyse the stochastic behaviour of heterogeneous, multi-scale cellular populations. We illustrate our methodology with a particular example in which we study a population with an oxygen-regulated proliferation rate. Our formulation is based on an age-dependent stochastic process. Cells within the population are characterised by their age (i.e. time elapsed since they were born). The age-dependent (oxygen-regulated) birth rate is given by a stochastic model of oxygen-dependent cell cycle progression. Once the birth rate is determined, we formulate an age-dependent birth-and-death process, which dictates the time evolution of the cell population. The population is under a feedback loop which controls its steady state size (carrying capacity): cells consume oxygen which in turn fuels cell proliferation. We show that our stochastic model of cell cycle progression allows for heterogeneity within the cell population induced by stochastic effects. Such heterogeneous behaviour is reflected in variations in the proliferation rate. Within this set-up, we have established three main results. First, we have shown that the age to the G1/S transition, which essentially determines the birth rate, exhibits a remarkably simple scaling behaviour. Besides the fact that this simple behaviour emerges from a rather complex model, this allows for a huge simplification of our numerical methodology. A further result is the observation that heterogeneous populations undergo an internal process of quasi-neutral competition. Finally, we investigated the effects of cell-cycle-phase dependent therapies (such as radiation therapy) on heterogeneous populations. In particular, we have studied the case in which the population contains a quiescent sub-population. Our mean-field analysis and numerical simulations confirm that, if the survival fraction of the therapy is too high, rescue of the quiescent population occurs. This gives rise to emergence of resistance

  3. World Population: Fundamentals of Growth. Student Chartbook. Third Edition.

    ERIC Educational Resources Information Center

    Kent, Mary Mederios

    This booklet is designed for K-12 students and educators to learn about world population growth factors. Data are shown through charts and graphs with brief explanations. The booklet contains: (1) "World Population Growth and Regional Distribution through History"; (2) "Population Growth through Natural Increase"; (3) "Effect of Migration on…

  4. Dynamic Heterogeneity of the Heart Valve Interstitial Cell Population in Mitral Valve Health and Disease

    PubMed Central

    Sauls, Kimberly; Koenig, Sara N.; Anstine, Lindsey J.; Garg, Vidu; Norris, Russell A.; Lincoln, Joy

    2015-01-01

    The heart valve interstitial cell (VIC) population is dynamic and thought to mediate lay down and maintenance of the tri-laminar extracellular matrix (ECM) structure within the developing and mature valve throughout life. Disturbances in the contribution and distribution of valve ECM components are detrimental to biomechanical function and associated with disease. This pathological process is associated with activation of resident VICs that in the absence of disease reside as quiescent cells. While these paradigms have been long standing, characterization of this abundant and ever-changing valve cell population is incomplete. Here we examine the expression pattern of Smooth muscle α-actin, Periostin, Twist1 and Vimentin in cultured VICs, heart valves from healthy embryonic, postnatal and adult mice, as well as mature valves from human patients and established mouse models of disease. We show that the VIC population is highly heterogeneous and phenotypes are dependent on age, species, location, and disease state. Furthermore, we identify phenotypic diversity across common models of mitral valve disease. These studies significantly contribute to characterizing the VIC population in health and disease and provide insights into the cellular dynamics that maintain valve structure in healthy adults and mediate pathologic remodeling in disease states. PMID:26527432

  5. Mitochondrial DNA from El Mirador Cave (Atapuerca, Spain) Reveals the Heterogeneity of Chalcolithic Populations

    PubMed Central

    Pierini, Federica; Matas-Lalueza, Laura; Gigli, Elena; Lari, Martina; Civit, Sergi; Lozano, Marina; Vergès, Josep Maria; Caramelli, David; Ramírez, Oscar; Lalueza-Fox, Carles

    2014-01-01

    Previous mitochondrial DNA analyses on ancient European remains have suggested that the current distribution of haplogroup H was modeled by the expansion of the Bell Beaker culture (ca 4,500–4,050 years BP) out of Iberia during the Chalcolithic period. However, little is known on the genetic composition of contemporaneous Iberian populations that do not carry the archaeological tool kit defining this culture. Here we have retrieved mitochondrial DNA (mtDNA) sequences from 19 individuals from a Chalcolithic sample from El Mirador cave in Spain, dated to 4,760–4,200 years BP and we have analyzed the haplogroup composition in the context of modern and ancient populations. Regarding extant African, Asian and European populations, El Mirador shows affinities with Near Eastern groups. In different analyses with other ancient samples, El Mirador clusters with Middle and Late Neolithic populations from Germany, belonging to the Rössen, the Salzmünde and the Baalberge archaeological cultures but not with contemporaneous Bell Beakers. Our analyses support the existence of a common genetic signal between Western and Central Europe during the Middle and Late Neolithic and points to a heterogeneous genetic landscape among Chalcolithic groups. PMID:25116044

  6. Mouse V1 population correlates of visual detection rely on heterogeneity within neuronal response patterns

    PubMed Central

    Montijn, Jorrit S; Goltstein, Pieter M; Pennartz, Cyriel MA

    2015-01-01

    Previous studies have demonstrated the importance of the primary sensory cortex for the detection, discrimination, and awareness of visual stimuli, but it is unknown how neuronal populations in this area process detected and undetected stimuli differently. Critical differences may reside in the mean strength of responses to visual stimuli, as reflected in bulk signals detectable in functional magnetic resonance imaging, electro-encephalogram, or magnetoencephalography studies, or may be more subtly composed of differentiated activity of individual sensory neurons. Quantifying single-cell Ca2+ responses to visual stimuli recorded with in vivo two-photon imaging, we found that visual detection correlates more strongly with population response heterogeneity rather than overall response strength. Moreover, neuronal populations showed consistencies in activation patterns across temporally spaced trials in association with hit responses, but not during nondetections. Contrary to models relying on temporally stable networks or bulk signaling, these results suggest that detection depends on transient differentiation in neuronal activity within cortical populations. DOI: http://dx.doi.org/10.7554/eLife.10163.001 PMID:26646184

  7. Psychoeducation in an Outpatient Setting--Designing a Heterogeneous Format for a Heterogeneous Population of Juvenile Delinquents.

    ERIC Educational Resources Information Center

    Carpenter, Patricia; Sugrue, Dennis P.

    1984-01-01

    Describes the G.I.T. (Getting It Together) program, a heterogeneous delinquent treatment program combining affective education and social skills training. Delinquents with immature personalities or neurotic features appeared to benefit more from the program than those with characterological disorders. (JAC)

  8. Deep-sequencing of the peach latent mosaic viroid reveals new aspects of population heterogeneity.

    PubMed

    Glouzon, Jean-Pierre Sehi; Bolduc, François; Wang, Shengrui; Najmanovich, Rafael J; Perreault, Jean-Pierre

    2014-01-01

    Viroids are small circular single-stranded infectious RNAs characterized by a relatively high mutation level. Knowledge of their sequence heterogeneity remains largely elusive and previous studies, using Sanger sequencing, were based on a limited number of sequences. In an attempt to address sequence heterogeneity from a population dynamics perspective, a GF305-indicator peach tree was infected with a single variant of the Avsunviroidae family member Peach latent mosaic viroid (PLMVd). Six months post-inoculation, full-length circular conformers of PLMVd were isolated and deep-sequenced. We devised an original approach to the bioinformatics refinement of our sequence libraries involving important phenotypic data, based on the systematic analysis of hammerhead self-cleavage activity. Two distinct libraries yielded a total of 3,939 different PLMVd variants. Sequence variants exhibiting up to ∼17% of mutations relative to the inoculated viroid were retrieved, clearly illustrating the high level of divergence dynamics within a unique population. While we initially assumed that most positions of the viroid sequence would mutate, we were surprised to discover that ∼50% of positions remained perfectly conserved, including several small stretches as well as a small motif reminiscent of a GNRA tetraloop which are the result of various selective pressures. Using a hierarchical clustering algorithm, the different variants harvested were subdivided into 7 clusters. We found that most sequences contained an average of 4.6 to 6.4 mutations compared to the variant used to initially inoculate the plant. Interestingly, it was possible to reconstitute and compare the sequence evolution of each of these clusters. In doing so, we identified several key mutations. This study provides a reliable pipeline for the treatment of viroid deep-sequencing. It also sheds new light on the extent of sequence variation that a viroid population can sustain, and which may give rise to a

  9. Evidence That the Heterogeneity of a T4 Population Is the Result of Heritable Traits

    PubMed Central

    Storms, Zachary J.; Sauvageau, Dominic

    2014-01-01

    Many bacteriophage populations display heterogeneity in their adsorption characteristics; a portion of the phage population remains free in solution throughout adsorption experiments (residual fraction). This residual fraction generally constitutes a minority of phages that exhibit significantly slower adsorption kinetics than the main phage stock (main fraction). While this phenomenon is likely the result of evolutionary driving forces, the present study demonstrates that the residual fraction is not always the result of phenotypic variations within a single genotype, as is generally thought. Experiments with phage T4 showed that two subgroups with distinct adsorption traits that were passed on to their progeny could be isolated from the original phage stock. Sequencing of genes involved in adsorption revealed two point mutations in gene 37 of residual fraction isolates, which resulted in modifications to the long tail-fiber, the organelle of attachment and host cell recognition. Adsorption studies consistently showed that T4 phage stocks amplified from residual fraction isolates had significantly lower adsorption efficiencies than those amplified from main fractions. The conducted experiments provide convincing evidence that the observed heterogeneity in T4 adsorption behavior is the result of conserved mutations to the phage genome and is not exclusively the result of phenotypic variations within the population. While it is believed high mutation rates exist to hasten phage adaptation, this study shows that this bet hedging strategy can also, in the short term, inadvertently handicap the phage's adsorption capabilities to a given host under normal infection conditions, resulting in the residual fraction observed in adsorption experiments. PMID:25551763

  10. IL12B expression is sustained by a heterogenous population of myeloid lineages during tuberculosis

    PubMed Central

    Reeme, Allison E.; Miller, Halli E.; Robinson, Richard T.

    2015-01-01

    Summary IL12B is required for resistance to Mycobacterium tuberculosis (Mtb) infection, promoting the initiation and maintenance of Mtb-specific effector responses. While this makes the IL12-pathway an attractive target for experimental tuberculosis (TB) therapies, data regarding what lineages express IL12B after infection is established are limited. This is not obvious in the lung, an organ in which both hematopoietic and non-hematopoietic lineages produce IL12p40 upon pathogen encounter. Here, we use radiation bone marrow chimeras and Yet40 reporter mice to determine what lineages produce IL12p40 during experimental TB. We observed that hematopoietic IL12p40-production was sufficient to control Mtb, with no contribution by non-hematopoietic lineages. Furthermore, rather than being produced by a single subset, IL12p40 was produced by cells that were heterogenous in their size, granularity, autofluorescence and expression of CD11c, CD11b and CD8α. While depending on the timepoint and tissue examined, the surface phenotype of IL12p40-producers most closely resembled macrophages based on previous surveys of lung myeloid lineages. Importantly, depletion of CDllchi cells during infection had no affect on lung IL12p40-concentrations. Collectively, our data demonstrate that IL12p40 production is sustained by a heterogenous population of myeloid lineages during experimental TB, and that redundant mechanisms of IL12p40-production exist when CD11chi lineages are absent. PMID:23491716

  11. A finite mixture model for genotype and environment interactions: Detecting latent population heterogeneity

    PubMed Central

    Gillespie, Nathan A.; Neale, Michael C.

    2013-01-01

    Approaches such as DeFries-Fulker extremes regression (LaBuda et al., 1986) are commonly used in genetically informative studies to assess whether familial resemblance varies as a function of the scores of pairs of twins. While useful for detecting such effects, formal modelling of differences in variance components as a function of pairs' trait scores is rarely attempted. We therefore present a finite mixture model which specifies that the population consists of latent groups which may differ in i) their means, and ii) the relative impact of genetic and environmental factors on within-group variation and covariation. This model may be considered as a special case of a factor mixture model, which combines the features of a latent class model with those of a latent trait model. Various models for the class membership of twin pairs may be employed, including additive genetic, common environment, specific environment or major locus (QTL) factors. Simulation results based on variance components derived from Turkheimer and colleagues (2003), illustrate the impact of factors such as the difference in group means and variance components on the feasibility of correctly estimating the parameters of the mixture model. Model-fitting analyses estimated group heritability as .49, which is significantly greater than heritability for the rest of the population in early childhood. These results suggest that factor mixture modelling is sufficiently robust for detecting heterogeneous populations even when group mean differences are modest. PMID:16790151

  12. Population Genomics Reveals Chromosome-Scale Heterogeneous Evolution in a Protoploid Yeast

    PubMed Central

    Friedrich, Anne; Jung, Paul; Reisser, Cyrielle; Fischer, Gilles; Schacherer, Joseph

    2015-01-01

    Yeast species represent an ideal model system for population genomic studies but large-scale polymorphism surveys have only been reported for species of the Saccharomyces genus so far. Hence, little is known about intraspecific diversity and evolution in yeast. To obtain a new insight into the evolutionary forces shaping natural populations, we sequenced the genomes of an expansive worldwide collection of isolates from a species distantly related to Saccharomyces cerevisiae: Lachancea kluyveri (formerly S. kluyveri). We identified 6.5 million single nucleotide polymorphisms and showed that a large introgression event of 1 Mb of GC-rich sequence in the chromosomal arm probably occurred in the last common ancestor of all L. kluyveri strains. Our population genomic data clearly revealed that this 1-Mb region underwent a molecular evolution pattern very different from the rest of the genome. It is characterized by a higher recombination rate, with a dramatically elevated A:T → G:C substitution rate, which is the signature of an increased GC-biased gene conversion. In addition, the predicted base composition at equilibrium demonstrates that the chromosome-scale compositional heterogeneity will persist after the genome has reached mutational equilibrium. Altogether, the data presented herein clearly show that distinct recombination and substitution regimes can coexist and lead to different evolutionary patterns within a single genome. PMID:25349286

  13. Population genomics reveals chromosome-scale heterogeneous evolution in a protoploid yeast.

    PubMed

    Friedrich, Anne; Jung, Paul; Reisser, Cyrielle; Fischer, Gilles; Schacherer, Joseph

    2015-01-01

    Yeast species represent an ideal model system for population genomic studies but large-scale polymorphism surveys have only been reported for species of the Saccharomyces genus so far. Hence, little is known about intraspecific diversity and evolution in yeast. To obtain a new insight into the evolutionary forces shaping natural populations, we sequenced the genomes of an expansive worldwide collection of isolates from a species distantly related to Saccharomyces cerevisiae: Lachancea kluyveri (formerly S. kluyveri). We identified 6.5 million single nucleotide polymorphisms and showed that a large introgression event of 1 Mb of GC-rich sequence in the chromosomal arm probably occurred in the last common ancestor of all L. kluyveri strains. Our population genomic data clearly revealed that this 1-Mb region underwent a molecular evolution pattern very different from the rest of the genome. It is characterized by a higher recombination rate, with a dramatically elevated A:T → G:C substitution rate, which is the signature of an increased GC-biased gene conversion. In addition, the predicted base composition at equilibrium demonstrates that the chromosome-scale compositional heterogeneity will persist after the genome has reached mutational equilibrium. Altogether, the data presented herein clearly show that distinct recombination and substitution regimes can coexist and lead to different evolutionary patterns within a single genome. PMID:25349286

  14. Proteomic comparison defines novel markers to characterize heterogeneous populations of extracellular vesicle subtypes.

    PubMed

    Kowal, Joanna; Arras, Guillaume; Colombo, Marina; Jouve, Mabel; Morath, Jakob Paul; Primdal-Bengtson, Bjarke; Dingli, Florent; Loew, Damarys; Tkach, Mercedes; Théry, Clotilde

    2016-02-23

    Extracellular vesicles (EVs) have become the focus of rising interest because of their numerous functions in physiology and pathology. Cells release heterogeneous vesicles of different sizes and intracellular origins, including small EVs formed inside endosomal compartments (i.e., exosomes) and EVs of various sizes budding from the plasma membrane. Specific markers for the analysis and isolation of different EV populations are missing, imposing important limitations to understanding EV functions. Here, EVs from human dendritic cells were first separated by their sedimentation speed, and then either by their behavior upon upward floatation into iodixanol gradients or by immuno-isolation. Extensive quantitative proteomic analysis allowing comparison of the isolated populations showed that several classically used exosome markers, like major histocompatibility complex, flotillin, and heat-shock 70-kDa proteins, are similarly present in all EVs. We identified proteins specifically enriched in small EVs, and define a set of five protein categories displaying different relative abundance in distinct EV populations. We demonstrate the presence of exosomal and nonexosomal subpopulations within small EVs, and propose their differential separation by immuno-isolation using either CD63, CD81, or CD9. Our work thus provides guidelines to define subtypes of EVs for future functional studies. PMID:26858453

  15. Proteomic comparison defines novel markers to characterize heterogeneous populations of extracellular vesicle subtypes

    PubMed Central

    Kowal, Joanna; Arras, Guillaume; Colombo, Marina; Jouve, Mabel; Morath, Jakob Paul; Primdal-Bengtson, Bjarke; Dingli, Florent; Tkach, Mercedes; Théry, Clotilde

    2016-01-01

    Extracellular vesicles (EVs) have become the focus of rising interest because of their numerous functions in physiology and pathology. Cells release heterogeneous vesicles of different sizes and intracellular origins, including small EVs formed inside endosomal compartments (i.e., exosomes) and EVs of various sizes budding from the plasma membrane. Specific markers for the analysis and isolation of different EV populations are missing, imposing important limitations to understanding EV functions. Here, EVs from human dendritic cells were first separated by their sedimentation speed, and then either by their behavior upon upward floatation into iodixanol gradients or by immuno-isolation. Extensive quantitative proteomic analysis allowing comparison of the isolated populations showed that several classically used exosome markers, like major histocompatibility complex, flotillin, and heat-shock 70-kDa proteins, are similarly present in all EVs. We identified proteins specifically enriched in small EVs, and define a set of five protein categories displaying different relative abundance in distinct EV populations. We demonstrate the presence of exosomal and nonexosomal subpopulations within small EVs, and propose their differential separation by immuno-isolation using either CD63, CD81, or CD9. Our work thus provides guidelines to define subtypes of EVs for future functional studies. PMID:26858453

  16. Impact of Pathogen Population Heterogeneity and Stress-Resistant Variants on Food Safety.

    PubMed

    Abee, T; Koomen, J; Metselaar, K I; Zwietering, M H; den Besten, H M W

    2016-01-01

    This review elucidates the state-of-the-art knowledge about pathogen population heterogeneity and describes the genotypic and phenotypic analyses of persister subpopulations and stress-resistant variants. The molecular mechanisms underlying the generation of persister phenotypes and genetic variants are identified. Zooming in on Listeria monocytogenes, a comparative whole-genome sequence analysis of wild types and variants that enabled the identification of mutations in variants obtained after a single exposure to lethal food-relevant stresses is described. Genotypic and phenotypic features are compared to those for persistent strains isolated from food processing environments. Inactivation kinetics, models used for fitting, and the concept of kinetic modeling-based schemes for detection of variants are presented. Furthermore, robustness and fitness parameters of L. monocytogenes wild type and variants are used to model their performance in food chains. Finally, the impact of stress-resistant variants and persistence in food processing environments on food safety is discussed. PMID:26772414

  17. Microselection – affinity selecting antibodies against a single rare cell in a heterogeneous population

    PubMed Central

    Sørensen, Morten Dræby; Agerholm, Inge Errebo; Christensen, Britta; Kølvraa, Steen; Kristensen, Peter

    2010-01-01

    Abstract Rare cells not normally present in the peripheral bloodstream, such as circulating tumour cells, have potential applications for development of non-invasive methods for diagnostics or follow up. Obtaining these cells however require some means of discrimination, achievable by cell type specific antibodies. Here we have generated a microselection method allowing antibody selection, by phage display, targeting a single cell in a heterogeneous population. One K562 cell (female origin) was positioned on glass slide among millions of lymphocytes from male donor, identifying the K562 cell by FISH (XX). Several single cell selections were performed on such individual slides. The phage particles bound to the target cell is protected by a minute disc, while inactivating all remaining phage by UV-irradiation; leaving only the phage bound to the target cell viable. We hereby retrieved up to eight antibodies per single cell selection, including three highly K562 cell type specific. PMID:20726925

  18. U.S. Population: Charting the Change. A Population Learning Series. Student Chartbook.

    ERIC Educational Resources Information Center

    Crews, Kimberly A.; Concellier, Patricia

    This student chartbook on the demography of the United States uses text and corresponding maps and charts to teach demographic concepts and terminology. The first reading, "Population Change in the U.S." explains natural increase, net migration, and growth or decrease of population for 1980-1986. The second reading, "U.S. Population by Age and…

  19. Heterogeneity in Genetic Diversity among Non-Coding Loci Fails to Fit Neutral Coalescent Models of Population History

    PubMed Central

    Peters, Jeffrey L.; Roberts, Trina E.; Winker, Kevin; McCracken, Kevin G.

    2012-01-01

    Inferring aspects of the population histories of species using coalescent analyses of non-coding nuclear DNA has grown in popularity. These inferences, such as divergence, gene flow, and changes in population size, assume that genetic data reflect simple population histories and neutral evolutionary processes. However, violating model assumptions can result in a poor fit between empirical data and the models. We sampled 22 nuclear intron sequences from at least 19 different chromosomes (a genomic transect) to test for deviations from selective neutrality in the gadwall (Anas strepera), a Holarctic duck. Nucleotide diversity among these loci varied by nearly two orders of magnitude (from 0.0004 to 0.029), and this heterogeneity could not be explained by differences in substitution rates alone. Using two different coalescent methods to infer models of population history and then simulating neutral genetic diversity under these models, we found that the observed among-locus heterogeneity in nucleotide diversity was significantly higher than expected for these simple models. Defining more complex models of population history demonstrated that a pre-divergence bottleneck was also unlikely to explain this heterogeneity. However, both selection and interspecific hybridization could account for the heterogeneity observed among loci. Regardless of the cause of the deviation, our results illustrate that violating key assumptions of coalescent models can mislead inferences of population history. PMID:22384117

  20. Orientation Courses: Meeting the Needs of Different Student Populations.

    ERIC Educational Resources Information Center

    Higbee, Jeanne L.

    A model that includes three distinct syllabi for orientation courses for different subgroups of the college or university freshman population is presented. Among the groups with special needs are underprepared students who may be motivated but need skill development, and underachieving students characterized by untapped potential. One means of…

  1. Combined Single-Cell Functional and Gene Expression Analysis Resolves Heterogeneity within Stem Cell Populations

    PubMed Central

    Wilson, Nicola K.; Kent, David G.; Buettner, Florian; Shehata, Mona; Macaulay, Iain C.; Calero-Nieto, Fernando J.; Sánchez Castillo, Manuel; Oedekoven, Caroline A.; Diamanti, Evangelia; Schulte, Reiner; Ponting, Chris P.; Voet, Thierry; Caldas, Carlos; Stingl, John; Green, Anthony R.; Theis, Fabian J.; Göttgens, Berthold

    2015-01-01

    Summary Heterogeneity within the self-renewal durability of adult hematopoietic stem cells (HSCs) challenges our understanding of the molecular framework underlying HSC function. Gene expression studies have been hampered by the presence of multiple HSC subtypes and contaminating non-HSCs in bulk HSC populations. To gain deeper insight into the gene expression program of murine HSCs, we combined single-cell functional assays with flow cytometric index sorting and single-cell gene expression assays. Through bioinformatic integration of these datasets, we designed an unbiased sorting strategy that separates non-HSCs away from HSCs, and single-cell transplantation experiments using the enriched population were combined with RNA-seq data to identify key molecules that associate with long-term durable self-renewal, producing a single-cell molecular dataset that is linked to functional stem cell activity. Finally, we demonstrated the broader applicability of this approach for linking key molecules with defined cellular functions in another stem cell system. PMID:26004780

  2. 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

  3. Mapping the Misunderstood Population of Adult Students

    ERIC Educational Resources Information Center

    Ashburn, Elyse

    2007-01-01

    Adult students are not well documented, are frequently left out of discussions of higher-education policy, and are not fully understood by the colleges they attend, says a report ("Returning to Learning: Adults' Success in College is Key to America's Future") released this week by the Lumina Foundation for Education. As a result, those students…

  4. Heterogeneity in ALSFRS-R decline and survival: a population-based study in Italy.

    PubMed

    Mandrioli, Jessica; Biguzzi, Sara; Guidi, Carlo; Sette, Elisabetta; Terlizzi, Emilio; Ravasio, Alessandro; Casmiro, Mario; Salvi, Fabrizio; Liguori, Rocco; Rizzi, Romana; Pietrini, Vladimiro; Borghi, Annamaria; Rinaldi, Rita; Fini, Nicola; Chierici, Elisabetta; Santangelo, Mario; Granieri, Enrico; Mussuto, Vittoria; De Pasqua, Silvia; Georgoulopoulou, Eleni; Fasano, Antonio; Ferro, Salvatore; D'Alessandro, Roberto

    2015-12-01

    Very few studies examined trend over time of the revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) and factors influencing it; previous studies, then, included only patients attending tertiary ALS Centres. We studied ALSFRS-R decline, factors influencing this trend and survival in a population-based setting. From 2009 onwards, a prospective registry records all incident ALS cases among residents in Emilia Romagna (population: 4.4 million). For each patient, demographic and clinical details (including ALSFRS-R) are collected by caring physicians at each follow-up. Analysis was performed on 402 incident cases (1279 ALSFRS-R assessments). The average decline of the ALSFRS-R was 0.60 points/month during the first year after diagnosis and 0.34 points/month in the second year. ALSFRS-R decline was heterogeneous among subgroups. Repeated measures mixed model showed that ALSFRS-R score decline was influenced by age at onset (p < 0.01), phenotype (p = 0.01), body mass index (BMI) (p < 0.01), progression rate at diagnosis (ΔFS) (p < 0.01), El Escorial Criteria-Revised (p < 0.01), and FVC% at diagnosis (p < 0.01). Among these factors, at multivariate analysis, only age, site of onset and ΔFS independently influenced survival. In this first population-based study on ALSFRS-R trend, we confirm that ALSFRS-R decline is not homogeneous among ALS patients and during the disease. Factors influencing ALSFRS-R decline may not match with those affecting survival. These disease modifiers should be taken into consideration for trials design and in clinical practice during discussions with patients on prognosis. PMID:26205535

  5. Preparing BSN Students for Population-Focused Nursing Care.

    PubMed

    Randolph, Schenita; Evans, Charlotte; Bacon, Cynthia T

    2016-01-01

    A baccalaureate nursing program in central North Carolina, in partnership with a local homeless shelter and community clinic, serves a vulnerable, underserved population while helping students gain hands-on experience in population-focused nursing. Students assess health needs, issues in access to care, and other health challenges using health assessment tools, surveys, and one-on-one dialogue. They then prioritize the top three health challenges and issues for the population and plan and implement educational sessions. After this experience, students report greater understanding of the concepts of community health and are able to apply them in practice. It is recommended that others considering this approach collect data to document the effectiveness of services to the population served and for funding of such initiatives. PMID:27209874

  6. Population-level thermal performance of a cold-water ectotherm is linked to ontogeny and local environmental heterogeneity

    USGS Publications Warehouse

    Hossack, Blake R.; Corn, P. Stephen; , Winsor H. Lowe; , Molly A. H. Webb; , Mariah J. Talbott; , Kevin M. Kappenman

    2013-01-01

    5. Our experiments with a cold-water species show that population-level performance varies across small geographic scales and is linked to local environmental heterogeneity. This variation could influence the rate and mode of species-level responses to climate change, both by facilitating local persistence in the face of change

  7. Preface of the "Symposium on Mathematical Models and Methods to investigate Heterogeneity in Cell and Cell Population Biology"

    NASA Astrophysics Data System (ADS)

    Clairambault, Jean

    2016-06-01

    This session investigates hot topics related to mathematical representations of cell and cell population dynamics in biology and medicine, in particular, but not only, with applications to cancer. Methods in mathematical modelling and analysis, and in statistical inference using single-cell and cell population data, should contribute to focus this session on heterogeneity in cell populations. Among other methods are proposed: a) Intracellular protein dynamics and gene regulatory networks using ordinary/partial/delay differential equations (ODEs, PDEs, DDEs); b) Representation of cell population dynamics using agent-based models (ABMs) and/or PDEs; c) Hybrid models and multiscale models to integrate single-cell dynamics into cell population behaviour; d) Structured cell population dynamics and asymptotic evolution w.r.t. relevant traits; e) Heterogeneity in cancer cell populations: origin, evolution, phylogeny and methods of reconstruction; f) Drug resistance as an evolutionary phenotype: predicting and overcoming it in therapeutics; g) Theoretical therapeutic optimisation of combined drug treatments in cancer cell populations and in populations of other organisms, such as bacteria.

  8. Parasexual Ploidy Reduction Drives Population Heterogeneity Through Random and Transient Aneuploidy in Candida albicans

    PubMed Central

    Hickman, Meleah A.; Paulson, Carsten; Dudley, Aimee; Berman, Judith

    2015-01-01

    The opportunistic pathogen Candida albicans has a large repertoire of mechanisms to generate genetic and phenotypic diversity despite the lack of meiosis in its life cycle. Its parasexual cycle enables shifts in ploidy, which in turn facilitate recombination, aneuploidy, and homozygosis of whole chromosomes to fuel rapid adaptation. Here we show that the tetraploid state potentiates ploidy variation and drives population heterogeneity. In tetraploids, the rate of losing a single heterozygous marker [loss of heterozygosity (LOH)] is elevated ∼30-fold higher than the rate in diploid cells. Furthermore, isolates recovered after selection for LOH of one, two, or three markers were highly aneuploid, with a broad range of karyotypes including strains with a combination of di-, tri-, and tetrasomic chromosomes. We followed the ploidy trajectories for these tetraploid- and aneuploid-derived isolates, using a combination of flow cytometry and double-digestion restriction-site-associated DNA analyzed with next-generation sequencing. Isolates derived from either tetraploid or aneuploid isolates predominately resolved to a stable euploid state. The majority of isolates reduced to the conventional diploid state; however, stable triploid and tetraploid states were observed in ∼30% of the isolates. Notably, aneuploid isolates were more transient than tetraploid isolates, resolving to a euploid state within a few passages. Furthermore, the likelihood that a particular isolate will resolve to the same ploidy state in replicate evolution experiments is only ∼50%, supporting the idea that the chromosome loss process of the parasexual cycle is random and does not follow trajectories involving specific combinations of chromosomes. Together, our results indicate that tetraploid progenitors can produce populations of progeny cells with a high degree of genomic diversity, from altered ploidy to homozygosis, providing an excellent source of genetic variation upon which selection can

  9. Using noise to control heterogeneity of isogenic populations in homogenous environments

    NASA Astrophysics Data System (ADS)

    Szymańska, Paulina; Gritti, Nicola; Keegstra, Johannes M.; Soltani, Mohammad; Munsky, Brian

    2015-07-01

    We explore the extent to which the phenotypes of individual, genetically identical cells can be controlled independently from each other using only a single homogeneous environmental input. We show that such control is theoretically impossible if restricted to a deterministic setting, but it can be achieved readily if one exploits heterogeneities introduced at the single-cell level due to stochastic fluctuations in gene regulation. Using stochastic analyses of a bistable genetic toggle switch, we develop a control strategy that maximizes the chances that a chosen cell will express one phenotype, while the rest express another. The control mechanism uses UV radiation to enhance identically protein degradation in all cells. Control of individual cells is made possible only by monitoring stochastic protein fluctuations and applying UV control at favorable times and levels. For two identical cells, our stochastic control law can drive protein expression of a chosen cell above its neighbor with a better than 99% success rate. In a population of 30 identical cells, we can drive a given cell to remain consistently within the top 20%. Although cellular noise typically impairs predictability for biological responses, our results show that it can also simultaneously improve controllability for those same responses.

  10. Culture History and Population Heterogeneity as Determinants of Bacterial Adaptation: the Adaptomics of a Single Environmental Transition

    PubMed Central

    Ryall, Ben; Eydallin, Gustavo

    2012-01-01

    Summary: Diversity in adaptive responses is common within species and populations, especially when the heterogeneity of the frequently large populations found in environments is considered. By focusing on events in a single clonal population undergoing a single transition, we discuss how environmental cues and changes in growth rate initiate a multiplicity of adaptive pathways. Adaptation is a comprehensive process, and stochastic, regulatory, epigenetic, and mutational changes can contribute to fitness and overlap in timing and frequency. We identify culture history as a major determinant of both regulatory adaptations and microevolutionary change. Population history before a transition determines heterogeneities due to errors in translation, stochastic differences in regulation, the presence of aged, damaged, cheating, or dormant cells, and variations in intracellular metabolite or regulator concentrations. It matters whether bacteria come from dense, slow-growing, stressed, or structured states. Genotypic adaptations are history dependent due to variations in mutation supply, contingency gene changes, phase variation, lateral gene transfer, and genome amplifications. Phenotypic adaptations underpin genotypic changes in situations such as stress-induced mutagenesis or prophage induction or in biofilms to give a continuum of adaptive possibilities. Evolutionary selection additionally provides diverse adaptive outcomes in a single transition and generally does not result in single fitter types. The totality of heterogeneities in an adapting population increases the chance that at least some individuals meet immediate or future challenges. However, heterogeneity complicates the adaptomics of single transitions, and we propose that subpopulations will need to be integrated into future population biology and systems biology predictions of bacterial behavior. PMID:22933562

  11. Spatial invasion dynamics on random and unstructured meshes: implications for heterogeneous tumor populations.

    PubMed

    Manem, V S K; Kohandel, M; Komarova, N L; Sivaloganathan, S

    2014-05-21

    In this work we discuss a spatial evolutionary model for a heterogeneous cancer cell population. We consider the gain-of-function mutations that not only change the fitness potential of the mutant phenotypes against normal background cells but may also increase the relative motility of the mutant cells. The spatial modeling is implemented as a stochastic evolutionary system on a structured grid (a lattice, with random neighborhoods, which is not necessarily bi-directional) or on a two-dimensional unstructured mesh, i.e. a bi-directional graph with random numbers of neighbors. We present a computational approach to investigate the fixation probability of mutants in these spatial models. Additionally, we examine the effect of the migration potential on the spatial dynamics of mutants on unstructured meshes. Our results suggest that the probability of fixation is negatively correlated with the width of the distribution of the neighborhood size. Also, the fixation probability increases given a migration potential for mutants. We find that the fixation probability (of advantaged, disadvantaged and neutral mutants) on unstructured meshes is relatively smaller than the corresponding results on regular grids. More importantly, in the case of neutral mutants the introduction of a migration potential has a critical effect on the fixation probability and increases this by orders of magnitude. Further, we examine the effect of boundaries and as intuitively expected, the fixation probability is smaller on the boundary of regular grids when compared to its value in the bulk. Based on these computational results, we speculate on possible better therapeutic strategies that may delay tumor progression to some extent. PMID:24462897

  12. Genetic heterogeneity and population structure of Gond-related tribes in the Vidarbha region of Maharashtra.

    PubMed

    Rao, V R; Sathe, M S; Gorakshakar, A C; Vasantha, K

    1992-12-01

    Genetic heterogeneity in nine polymorphic loci is observed among Gond-related tribes in the Vidarbha region of Maharashtra. Pardhans, with their high ABO*A2 gene frequency (4.01%), low m gene frequency (57%), high P*1 gene frequency (42.7%), and high HbS trait (31.58%), differ significantly from other tribes. Per locus average heterozygosity among the studied tribes ranged from 36.24% to 40.37%, with Pardhans being more heterozygous. Analysis by FST and the empirical relationship between average allele frequencies and the ratio of within-gene to total gene diversity show that the tribes are isolated and that differentiation among them is at an early stage and approximately in conformity with expected differentiation under genetic drift. However, distances and principal components analysis reveal that Pardhans are far removed from the other tribes and from other central Dravidian tribes. Furthermore, of the various demographic parameters estimated, the high average heterozygosity in Pardhans is significantly correlated with mean marital distance (MMD), regression of MMD on wife's age, and effective population size. There is congruence between genetic and demographic data, showing that Pardhans are distinct. This conforms with Haimendorf's (1979) contention based on cultural traits that Pardhans are Gonds by historical accident and are later migrants to the Gond area from the north. The most significant and practical observation of the present study is that migration from an originally nontribal (Pardhan) to a tribal (Gond) area and admixture lead to severe disease course, differential selection pressure, and hence highly elevated HbS trait frequency. PMID:1427746

  13. CHIP buffers heterogeneous Bcl-2 expression levels to prevent augmentation of anticancer drug-resistant cell population.

    PubMed

    Tsuchiya, M; Nakajima, Y; Waku, T; Hiyoshi, H; Morishita, T; Furumai, R; Hayashi, Y; Kishimoto, H; Kimura, K; Yanagisawa, J

    2015-08-27

    Many types of cancer display heterogeneity in various features, including gene expression and malignant potential. This heterogeneity is associated with drug resistance and cancer progression. Recent studies have shown that the expression of a major protein quality control ubiquitin ligase, carboxyl terminus of Hsc70-interacting protein (CHIP), is negatively correlated with breast cancer clinicopathological stages and poor overall survival. Here we show that CHIP acts as a capacitor of heterogeneous Bcl-2 expression levels and prevents an increase in the anticancer drug-resistant population in breast cancer cells. CHIP knockdown in breast cancer cells increased variation in Bcl-2 expression levels, an antiapoptotic protein, among the cells. Our results also showed that CHIP knockdown increased the proportion of anticancer drug-resistant cells. These findings suggest that CHIP buffers variation in gene expression levels, affecting resistance to anticancer drugs. In single-cell clones derived from breast cancer cell lines, CHIP knockdown did not alter the variation in Bcl-2 expression levels and the proportion of anticancer drug-resistant cells. In contrast, when clonal cells were treated with a mutagen, the variation in Bcl-2 expression levels and proportion of anticancer drug-resistant cells were altered by CHIP knockdown. These results suggest that CHIP masks genetic variations to suppress heterogeneous Bcl-2 expression levels and prevents augmentation of the anticancer drug-resistant population of breast cancer cells. Because genetic variation is a major driver of heterogeneity, our results suggest that the degree of heterogeneity in expression levels is decided by a balance between genetic variation and the buffering capacity of CHIP. PMID:25435366

  14. Use of posterior predictive checks as an inferential tool for investigating individual heterogeneity in animal population vital rates

    PubMed Central

    Chambert, Thierry; Rotella, Jay J; Higgs, Megan D

    2014-01-01

    The investigation of individual heterogeneity in vital rates has recently received growing attention among population ecologists. Individual heterogeneity in wild animal populations has been accounted for and quantified by including individually varying effects in models for mark–recapture data, but the real need for underlying individual effects to account for observed levels of individual variation has recently been questioned by the work of Tuljapurkar et al. (Ecology Letters, 12, 93, 2009) on dynamic heterogeneity. Model-selection approaches based on information criteria or Bayes factors have been used to address this question. Here, we suggest that, in addition to model-selection, model-checking methods can provide additional important insights to tackle this issue, as they allow one to evaluate a model's misfit in terms of ecologically meaningful measures. Specifically, we propose the use of posterior predictive checks to explicitly assess discrepancies between a model and the data, and we explain how to incorporate model checking into the inferential process used to assess the practical implications of ignoring individual heterogeneity. Posterior predictive checking is a straightforward and flexible approach for performing model checks in a Bayesian framework that is based on comparisons of observed data to model-generated replications of the data, where parameter uncertainty is incorporated through use of the posterior distribution. If discrepancy measures are chosen carefully and are relevant to the scientific context, posterior predictive checks can provide important information allowing for more efficient model refinement. We illustrate this approach using analyses of vital rates with long-term mark–recapture data for Weddell seals and emphasize its utility for identifying shortfalls or successes of a model at representing a biological process or pattern of interest. We show how posterior predictive checks can be used to strengthen inferences in

  15. Student-Teacher Population Growth Model. Working Paper.

    ERIC Educational Resources Information Center

    Zabrowski, Edward K.; And Others

    This mathematical model of the educational system calculates information on population groups by sex, race, age, and educational level. The model can be used to answer questions about what would happen to the flows of students and teachers through the formal educational system if these flows are changed at various stages. The report discusses the…

  16. Prevalence of Keratoconus Among a Palestinian Tertiary Student Population

    PubMed Central

    Shehadeh, Mohammad M.; Diakonis, Vasilios F.; Jalil, Sara A.; Younis, Rania; Qadoumi, Jamal; Al-Labadi, Liana

    2015-01-01

    Purpose: To screen for keratoconus and potential associated risk factors in a tertiary student population sample. Population and Methods: This cross sectional study included 1234 students attending An-Najah National University (Nablus, West Bank, Palestine), that were randomly selected from a total of 20,000 university students. 634 (51.3%) student participants responded by completing a self-administered questionnaire and were assessed by means of corneal topography. Following initial evaluation, participants were referred for Pentacam evaluation if they demonstrated either a mean keratometry of more than 45 diopters, corneal astigmatism of more than 2 diopters and/or if asymmetric topographic patterns were present. Pentacam images were analyzed by an experienced ophthalmologist based on a number of indices and the participants were classified as normal, keratoconus suspects, and keratoconus patients. Results: A total of 620 participants (mean age, 20.1±1.6 years) were included in this study, 379 (61.1%) were females and 241 (38.9%) were males. Nine subjects were diagnosed with keratoconus, demonstrating a prevalence of 1.5%. 52 (8.4%) participants showed at least one abnormal pentacam index, and were considered as KC suspects. Conclusion: Keratoconus is a prevalent disease among the tertiary Palestinian student population. This may be related to a combination of genetic and environmental factors. The results of this study signal the need for public health outreach and intervention for keratoconus. PMID:26962381

  17. Student and School Staff Strategies to Combat Cyberbullying in an Urban Student Population

    ERIC Educational Resources Information Center

    Pelfrey, William V., Jr.; Weber, Nicole L.

    2015-01-01

    Research indicates that cyberbullying is occurring among middle and high school student populations at increasing rates. There is limited research, however, on strategies students use to combat cyberbullying, as well as how schools implement policies, intervention tactics, and prevention strategies. This qualitative study aimed to explore, among a…

  18. Environmental heterogeneity generates opposite gene-by-environment interactions for two fitness-related traits within a population.

    PubMed

    Culumber, Zachary W; Schumer, Molly; Monks, Scott; Tobler, Michael

    2015-02-01

    Theory predicts that environmental heterogeneity offers a potential solution to the maintenance of genetic variation within populations, but empirical evidence remains sparse. The live-bearing fish Xiphophorus variatus exhibits polymorphism at a single locus, with different alleles resulting in up to five distinct melanistic "tailspot" patterns within populations. We investigated the effects of heterogeneity in two ubiquitous environmental variables (temperature and food availability) on two fitness-related traits (upper thermal limits and body condition) in two different tailspot types (wild-type and upper cut crescent). We found gene-by-environment (G × E) interactions between tailspot type and food level affecting upper thermal limits (UTL), as well as between tailspot type and thermal environment affecting body condition. Exploring mechanistic bases underlying these G × E patterns, we found no differences between tailspot types in hsp70 gene expression despite significant overall increases in expression under both thermal and food stress. Similarly, there was no difference in routine metabolic rates between the tailspot types. The reversal of relative performance of the two tailspot types under different environmental conditions revealed a mechanism by which environmental heterogeneity can balance polymorphism within populations through selection on different fitness-related traits. PMID:25496554

  19. Using heterogeneity of the patient-derived xenograft model to identify the chemoresistant population in ovarian cancer

    PubMed Central

    Dobbin, Zachary C.; Katre, Ashwini A.; Steg, Adam D.; Erickson, Britt K.; Shah, Monjri M.; Alvarez, Ronald D.; Conner, Michael G.; Schneider, David; Chen, Dongquan; Landen, Charles N.

    2014-01-01

    A cornerstone of preclinical cancer research has been the use of clonal cell lines. However, this resource has underperformed in its ability to effectively identify novel therapeutics and evaluate the heterogeneity in a patient's tumor. The patient-derived xenograft (PDX) model retains the heterogeneity of patient tumors, allowing a means to not only examine efficacy of a therapy, but also basic tenets of cancer biology in response to treatment. Herein we describe the development and characterization of an ovarian-PDX model in order to study the development of chemoresistance. We demonstrate that PDX tumors are not simply composed of tumor-initiating cells, but recapitulate the original tumor's heterogeneity, oncogene expression profiles, and clinical response to chemotherapy. Combined carboplatin/paclitaxel treatment of PDX tumors enriches the cancer stem cell populations, but persistent tumors are not entirely composed of these populations. RNA-Seq analysis of six pair of treated PDX tumors compared to untreated tumors demonstrates a consistently contrasting genetic profile after therapy, suggesting similar, but few, pathways are mediating chemoresistance. Pathways and genes identified by this methodology represent novel approaches to targeting the chemoresistant population in ovarian cancer PMID:25209969

  20. Comparative microsatellite typing of new world leishmania infantum reveals low heterogeneity among populations and its recent old world origin.

    PubMed

    Kuhls, Katrin; Alam, Mohammad Zahangir; Cupolillo, Elisa; Ferreira, Gabriel Eduardo M; Mauricio, Isabel L; Oddone, Rolando; Feliciangeli, M Dora; Wirth, Thierry; Miles, Michael A; Schönian, Gabriele

    2011-06-01

    Leishmania infantum (syn. L. chagasi) is the causative agent of visceral leishmaniasis (VL) in the New World (NW) with endemic regions extending from southern USA to northern Argentina. The two hypotheses about the origin of VL in the NW suggest (1) recent importation of L. infantum from the Old World (OW), or (2) an indigenous origin and a distinct taxonomic rank for the NW parasite. Multilocus microsatellite typing was applied in a survey of 98 L. infantum isolates from different NW foci. The microsatellite profiles obtained were compared to those of 308 L. infantum and 20 L. donovani strains from OW countries previously assigned to well-defined populations. Two main populations were identified for both NW and OW L. infantum. Most of the NW strains belonged to population 1, which corresponded to the OW MON-1 population. However, the NW population was much more homogeneous. A second, more heterogeneous, population comprised most Caribbean strains and corresponded to the OW non-MON-1 population. All Brazilian L. infantum strains belonged to population 1, although they represented 61% of the sample and originated from 9 states. Population analysis including the OW L. infantum populations indicated that the NW strains were more similar to MON-1 and non-MON-1 sub-populations of L. infantum from southwest Europe, than to any other OW sub-population. Moreover, similarity between NW and Southwest European L. infantum was higher than between OW L. infantum from distinct parts of the Mediterranean region, Middle East and Central Asia. No correlation was found between NW L. infantum genotypes and clinical picture or host background. This study represents the first continent-wide analysis of NW L. infantum population structure. It confirmed that the agent of VL in the NW is L. infantum and that the parasite has been recently imported multiple times to the NW from southwest Europe. PMID:21666787

  1. Comparative Microsatellite Typing of New World Leishmania infantum Reveals Low Heterogeneity among Populations and Its Recent Old World Origin

    PubMed Central

    Kuhls, Katrin; Alam, Mohammad Zahangir; Cupolillo, Elisa; Ferreira, Gabriel Eduardo M.; Mauricio, Isabel L.; Oddone, Rolando; Feliciangeli, M. Dora; Wirth, Thierry; Miles, Michael A.; Schönian, Gabriele

    2011-01-01

    Leishmania infantum (syn. L. chagasi) is the causative agent of visceral leishmaniasis (VL) in the New World (NW) with endemic regions extending from southern USA to northern Argentina. The two hypotheses about the origin of VL in the NW suggest (1) recent importation of L. infantum from the Old World (OW), or (2) an indigenous origin and a distinct taxonomic rank for the NW parasite. Multilocus microsatellite typing was applied in a survey of 98 L. infantum isolates from different NW foci. The microsatellite profiles obtained were compared to those of 308 L. infantum and 20 L. donovani strains from OW countries previously assigned to well-defined populations. Two main populations were identified for both NW and OW L. infantum. Most of the NW strains belonged to population 1, which corresponded to the OW MON-1 population. However, the NW population was much more homogeneous. A second, more heterogeneous, population comprised most Caribbean strains and corresponded to the OW non-MON-1 population. All Brazilian L. infantum strains belonged to population 1, although they represented 61% of the sample and originated from 9 states. Population analysis including the OW L. infantum populations indicated that the NW strains were more similar to MON-1 and non-MON-1 sub-populations of L. infantum from southwest Europe, than to any other OW sub-population. Moreover, similarity between NW and Southwest European L. infantum was higher than between OW L. infantum from distinct parts of the Mediterranean region, Middle East and Central Asia. No correlation was found between NW L. infantum genotypes and clinical picture or host background. This study represents the first continent-wide analysis of NW L. infantum population structure. It confirmed that the agent of VL in the NW is L. infantum and that the parasite has been recently imported multiple times to the NW from southwest Europe. PMID:21666787

  2. AG490 and PF431396 Sensitive Tyrosine Kinase Control the Population Heterogeneity of Basal STAT1 Activity in Ube1l Deficient Cells

    PubMed Central

    Now, Hesung; Yoo, Joo-Yeon

    2016-01-01

    A population often contains distinct sub-populations, thereby increasing the complexity of the overall heterogeneity. However, the cellular origin and biological relevance of sub-populations in cell population have not been clearly identified. Here we demonstrated the novel roles of ISGylation, which is an IFN-induced post-translational modification, controlling heterogeneity at the population level in cultured adherent cells. Without UBE1L, an E1 enzyme of ISGylation, mouse embryonic fibroblasts (MEF) exhibited low viral resistance despite high STAT1 and ISG expression compared with the wild-type MEF. We observe that Ube1l−/− MEF populations consist of two behaviorally distinguishable sub-populations with distinct basal STAT1 activity, while wild-type MEF populations are unimodal. This population heterogeneity in Ube1l knock-out cells was perturbed by tyrosine kinase inhibitors, AG490 and PF431396. In contrast, the neutralization of type I IFN did not affect population heterogeneity. Based on these results, we concluded that UBE1L functions to adjust basal immunological states with the regulation of population heterogeneity. PMID:27427993

  3. A Novel Staining Protocol for Multiparameter Assessment of Cell Heterogeneity in Phormidium Populations (Cyanobacteria) Employing Fluorescent Dyes

    PubMed Central

    Tashyreva, Daria; Elster, Josef; Billi, Daniela

    2013-01-01

    Bacterial populations display high heterogeneity in viability and physiological activity at the single-cell level, especially under stressful conditions. We demonstrate a novel staining protocol for multiparameter assessment of individual cells in physiologically heterogeneous populations of cyanobacteria. The protocol employs fluorescent probes, i.e., redox dye 5-cyano-2,3-ditolyl tetrazolium chloride, ‘dead cell’ nucleic acid stain SYTOX Green, and DNA-specific fluorochrome 4′,6-diamidino-2-phenylindole, combined with microscopy image analysis. Our method allows simultaneous estimates of cellular respiration activity, membrane and nucleoid integrity, and allows the detection of photosynthetic pigments fluorescence along with morphological observations. The staining protocol has been adjusted for, both, laboratory and natural populations of the genus Phormidium (Oscillatoriales), and tested on 4 field-collected samples and 12 laboratory strains of cyanobacteria. Based on the mentioned cellular functions we suggest classification of cells in cyanobacterial populations into four categories: (i) active and intact; (ii) injured but active; (iii) metabolically inactive but intact; (iv) inactive and injured, or dead. PMID:23437052

  4. Explaining Spatial Heterogeneity in Population Dynamics and Genetics from Spatial Variation in Resources for a Large Herbivore

    PubMed Central

    Contasti, Adrienne L.; Tissier, Emily J.; Johnstone, Jill F.; McLoughlin, Philip D.

    2012-01-01

    Fine-scale spatial variation in genetic relatedness and inbreeding occur across continuous distributions of several populations of vertebrates; however, the basis of observed variation is often left untested. Here we test the hypothesis that prior observations of spatial patterns in genetics for an island population of feral horses (Sable Island, Canada) were the result of spatial variation in population dynamics, itself based in spatial heterogeneity in underlying habitat quality. In order to assess how genetic and population structuring related to habitat, we used hierarchical cluster analysis of water sources and an indicator analysis of the availability of important forage species to identify a longitudinal gradient in habitat quality along the length of Sable Island. We quantify a west-east gradient in access to fresh water and availability of two important food species to horses: sandwort, Honckenya peploides, and beach pea, Lathyrus japonicas. Accordingly, the population clusters into three groups that occupy different island segments (west, central, and east) that vary markedly in their local dynamics. Density, body condition, and survival and reproduction of adult females were highest in the west, followed by central and east areas. These results mirror a previous analysis of genetics, which showed that inbreeding levels are highest in the west (with outbreeding in the east), and that there are significant differences in fixation indices among groups of horses along the length of Sable Island. Our results suggest that inbreeding depression is not an important limiting factor to the horse population. We conclude that where habitat gradients exist, we can anticipate fine-scale heterogeneity in population dynamics and hence genetics. PMID:23118900

  5. Population-based initiatives in college mental health: students helping students to overcome obstacles.

    PubMed

    Kirsch, Daniel J; Pinder-Amaker, Stephanie L; Morse, Charles; Ellison, Marsha L; Doerfler, Leonard A; Riba, Michelle B

    2014-12-01

    College students' need for mental health care has increased dramatically, leaving campus counseling and mental health centers struggling to meet the demand. This has led to the investigation and development of extra-center, population-based interventions. Student-to-student support programs are but one example. Students themselves are a plentiful, often-untapped resource that extends the reach of mental health services on campus. Student-to-student programs capitalize on students' natural inclination to assist their peers. A brief review of the prevalence and effects of mental disorders in the college population is provided, followed by a broad overview of the range of peer-to-peer programs that can be available on college campuses. Two innovative programs are highlighted: (1) a hospital- and community-based program, the College Mental Health Program (CMHP) at McLean Hospital, and 2) the Student Support Network (SSN) at Worcester Polytechnic Institute. The subsequent section reviews the literature on peer-to-peer programs for students with serious and persistent mental illness for which there is a small but generally positive body of research. This lack of an empirical basis in college mental health leads the authors to argue for development of broad practice-research networks. PMID:25308393

  6. Mechanisms of population genetic heterogeneity among molting common mergansers on Kodiak Island, Alaska: implications for assessments of migratory connectivity

    USGS Publications Warehouse

    Pearce, John M.; Zwiefelhofer, Denny; Maryanski, Nate

    2009-01-01

    Quantifying population genetic heterogeneity within nonbreeding aggregations can inform our understanding of patterns of site fidelity, migratory connectivity, and gene flow between breeding and nonbreeding areas. However, characterizing mechanisms that contribute to heterogeneity, such as migration and dispersal, is required before site fidelity and migratory connectivity can be assessed accurately. We studied nonbreeding groups of Common Mergansers (Mergus merganser) molting on Kodiak Island, Alaska, from 2005 to 2007, using banding data to assess rates of recapture, mitochondrial (mt) DNA to determine natal area, and nuclear microsatellite genotypes to assess dispersal. Using baseline information from differentiated mtDNA haplogroups across North America, we were able to assign individuals to natal regions and document population genetic heterogeneity within and among molting groups. Band-recovery and DNA data suggest that both migration from and dispersal among natal areas contribute to admixed groups of males molting on Kodiak Island. A lack of differentiation in the Common Merganser's nuclear, bi-parentally inherited DNA, observed across North America, implies that dispersal can mislead genetic assessments of migratory connectivity and assignments of nonbreeding individuals to breeding areas. Thus multiple and independent data types are required to account for such behaviors before accurate assessments of migratory connectivity can be made.

  7. Heterogeneous Catalysis.

    ERIC Educational Resources Information Center

    Miranda, R.

    1989-01-01

    Described is a heterogeneous catalysis course which has elements of materials processing embedded in the classical format of catalytic mechanisms and surface chemistry. A course outline and list of examples of recent review papers written by students are provided. (MVL)

  8. Understanding Internet Searching Performance in a Heterogeneous Portal for K-12 Students: Search Success, Search Time, Strategy, and Effort

    ERIC Educational Resources Information Center

    Zhang, Yin; Robins, David; Holmes, Jason; Salaba, Athena

    2009-01-01

    This study sought to better understand search performance using an online portal containing a collection of heterogeneous library resources for K-12 students. Search performance is examined in terms of search success, search time, strategy, and effort. This study revealed unsuccessful searches tended to take longer than successful searches;…

  9. Population.

    ERIC Educational Resources Information Center

    King, Pat; Landahl, John

    This pamphlet has been prepared in response to a new problem, a rapidly increasing population, and a new need, population education. It is designed to help teachers provide their students with some basic population concepts with stress placed on the elements of decision making. In the first section of the pamphlet, some of the basic concepts of…

  10. Between-airport heterogeneity in air toxics emissions associated with individual cancer risk thresholds and population risks

    PubMed Central

    2009-01-01

    Background Airports represent a complex source type of increasing importance contributing to air toxics risks. Comprehensive atmospheric dispersion models are beyond the scope of many applications, so it would be valuable to rapidly but accurately characterize the risk-relevant exposure implications of emissions at an airport. Methods In this study, we apply a high resolution atmospheric dispersion model (AERMOD) to 32 airports across the United States, focusing on benzene, 1,3-butadiene, and benzo [a]pyrene. We estimate the emission rates required at these airports to exceed a 10-6 lifetime cancer risk for the maximally exposed individual (emission thresholds) and estimate the total population risk at these emission rates. Results The emission thresholds vary by two orders of magnitude across airports, with variability predicted by proximity of populations to the airport and mixing height (R2 = 0.74–0.75 across pollutants). At these emission thresholds, the population risk within 50 km of the airport varies by two orders of magnitude across airports, driven by substantial heterogeneity in total population exposure per unit emissions that is related to population density and uncorrelated with emission thresholds. Conclusion Our findings indicate that site characteristics can be used to accurately predict maximum individual risk and total population risk at a given level of emissions, but that optimizing on one endpoint will be non-optimal for the other. PMID:19426510

  11. Flow cytometry and cell sorting of heterogeneous microbial populations: the importance of single-cell analyses.

    PubMed Central

    Davey, H M; Kell, D B

    1996-01-01

    The most fundamental questions such as whether a cell is alive, in the sense of being able to divide or to form a colony, may sometimes be very hard to answer, since even axenic microbial cultures are extremely heterogeneous. Analyses that seek to correlate such things as viability, which is a property of an individual cell, with macroscopic measurements of culture variables such as ATP content, respiratory activity, and so on, must inevitably fail. It is therefore necessary to make physiological measurements on individual cells. Flow cytometry is such a technique, which allows one to analyze cells rapidly and individually and permits the quantitative analysis of microbial heterogeneity. It therefore offers many advantages over conventional measurements for both routine and more exploratory analyses of microbial properties. While the technique has been widely applied to the study of mammalian cells, is use in microbiology has until recently been much more limited, largely because of the smaller size of microbes and the consequently smaller optical signals obtainable from them. Since these technical barriers no longer hold, flow cytometry with appropriate stains has been used for the rapid discrimination and identification of microbial cells, for the rapid assessment of viability and of the heterogeneous distributions of a wealth of other more detailed physiological properties, for the analysis of antimicrobial drug-cell interactions, and for the isolation of high-yielding strains of biotechnological interest. Flow cytometric analyses provide an abundance of multivariate data, and special methods have been devised to exploit these. Ongoing advances mean that modern flow cytometers may now be used by nonspecialists to effect a renaissance in our understanding of microbial heterogeneity. PMID:8987359

  12. Defining the Heterogeneity of Skeletal Muscle-Derived Side and Main Population Cells Isolated Immediately Ex Vivo

    PubMed Central

    KALLESTAD, KRISTEN M.; MCLOON, LINDA K.

    2011-01-01

    Myoblast transfer therapy for Duchenne muscular dystrophy (DMD) largely fails due to cell death and inability of transplanted cells to engraft in diseased muscles. One method attempting to enrich for cell subpopulations is the Hoechst 33342 dye exclusion assay, yielding a side population (SP) thought to be progenitor enriched and a main population (MP). However, in vitro and transplant studies yielded inconsistent results relative to downstream progeny. Cell surface markers expressed by skeletal muscle-derived MP and SP cells have not been fully characterized directly ex vivo. Using flow cytometry, MP and SP cells were characterized based on their expression of several well-accepted progenitor cell antigens. Both the MP and SP populations are heterogeneous and overlapping in the cells they contain. The percentages of cells in each population vary with species and specific muscle examined. MP and SP populations contain both satellite and multipotent progenitor cells, based on expression of CD34, Sca-1, Pax7, and M-cadherin. Thus, isolation using this procedure cannot be used to predict downstream differentiation outcomes, and explains the conflicting literature on these cells. Hoechst dye also results in significant mortality of sorted cells. As defined subpopulations are easily obtained using flow cytometry, sorting immediately ex vivo based on accepted myogenic precursor cell markers will yield superior results in terms of cell homogeneity for transplantation therapy. PMID:20020527

  13. Connectivity, passability and heterogeneity interact to determine fish population persistence in river networks

    PubMed Central

    Samia, Yasmine; Lutscher, Frithjof; Hastings, Alan

    2015-01-01

    The movement of fish in watersheds is frequently inhibited by human-made migration barriers such as dams or culverts. The resulting lack of connectivity of spatial subpopulations is often cited as a cause for observed population decline. We formulate a matrix model for a spatially distributed fish population in a watershed, and we investigate how location and other characteristics of a single movement barrier impact the asymptotic growth rate of the population. We find that while population growth rate often decreases with the introduction of a movement obstacle, it may also increase due to a ‘retention effect’. Furthermore, obstacle mortality greatly affects population growth rate. In practice, different connectivity indices are used to predict population effects of migration barriers, but the relation of these indices to population growth rates in demographic models is often unclear. When comparing our results with the dentritic connectivity index, we see that the index captures neither the retention effect nor the influences of obstacle mortality. We argue that structural indices cannot entirely replace more detailed demographic models to understand questions of persistence and extinction. We advocate the development of novel functional indices and characteristics. PMID:26311313

  14. Connectivity, passability and heterogeneity interact to determine fish population persistence in river networks.

    PubMed

    Samia, Yasmine; Lutscher, Frithjof; Hastings, Alan

    2015-09-01

    The movement of fish in watersheds is frequently inhibited by human-made migration barriers such as dams or culverts. The resulting lack of connectivity of spatial subpopulations is often cited as a cause for observed population decline. We formulate a matrix model for a spatially distributed fish population in a watershed, and we investigate how location and other characteristics of a single movement barrier impact the asymptotic growth rate of the population. We find that while population growth rate often decreases with the introduction of a movement obstacle, it may also increase due to a 'retention effect'. Furthermore, obstacle mortality greatly affects population growth rate. In practice, different connectivity indices are used to predict population effects of migration barriers, but the relation of these indices to population growth rates in demographic models is often unclear. When comparing our results with the dentritic connectivity index, we see that the index captures neither the retention effect nor the influences of obstacle mortality. We argue that structural indices cannot entirely replace more detailed demographic models to understand questions of persistence and extinction. We advocate the development of novel functional indices and characteristics. PMID:26311313

  15. Coyotes demonstrate how habitat specialization by individuals of a generalist species can diversify populations in a heterogeneous ecoregion.

    PubMed

    Sacks, Benjamin N; Bannasch, Danika L; Chomel, Bruno B; Ernest, Holly B

    2008-07-01

    The tendency for individuals to disperse into habitat similar to their natal habitat has been observed in a wide range of species, although its population genetic consequences have received little study. Such behavior could lead to discrete habitat-specific population subdivisions even in the absence of physical dispersal barriers or habitat gaps. Previous studies of coyotes have supported this hypothesis in a small region of California, but its evolutionary significance ultimately depends on the extent and magnitude of habitat-specific subdivision. Here, we investigated these questions using autosomal, Y chromosome, and mitochondrial markers and >2,000 coyotes from a broad region, including 2 adjacent ecoregions with contrasting levels of habitat heterogeneity--the California Floristic Province (CFP) (heterogeneous landscape) and the Desert-Prairie ecoregion (DPE) (homogeneous landscape). Consistent with predictions, we found a close correspondence between population genetic structure and habitat subdivisions throughout the CFP and virtual panmixia over the larger DPE. Conversely, although genetic diversity was similar in these 2 ecoregions overall, it was lower within sites of the CFP, as would be the expected consequence of greater genetic drift within subregions. The magnitude of habitat-specific genetic subdivisions (i.e., genetic distance) in the CFP varied considerably, indicating complexity (e.g., asymmetric gene flow or extinction/recolonization), but, in general, was higher than that due to geographic distance or recent human-related barriers. Because habitat-specific structure can enhance a species' adaptive potential and resilience to changing environments, these findings suggest the CFP may constitute an evolutionarily important portion of the range for coyotes and sympatric species exhibiting habitat-specific population structure. PMID:18391065

  16. The dynamic balance of import and export of zinc in Escherichia coli suggests a heterogeneous population response to stress

    PubMed Central

    Takahashi, Hiroki; Oshima, Taku; Hobman, Jon L.; Doherty, Neil; Clayton, Selina R.; Iqbal, Mudassar; Hill, Philip J.; Tobe, Toru; Ogasawara, Naotake; Kanaya, Shigehiko; Stekel, Dov J.

    2015-01-01

    Zinc is essential for life, but toxic in excess. Thus all cells must control their internal zinc concentration. We used a systems approach, alternating rounds of experiments and models, to further elucidate the zinc control systems in Escherichia coli. We measured the response to zinc of the main specific zinc import and export systems in the wild-type, and a series of deletion mutant strains. We interpreted these data with a detailed mathematical model and Bayesian model fitting routines. There are three key findings: first, that alternate, non-inducible importers and exporters are important. Second, that an internal zinc reservoir is essential for maintaining the internal zinc concentration. Third, our data fitting led us to propose that the cells mount a heterogeneous response to zinc: some respond effectively, while others die or stop growing. In a further round of experiments, we demonstrated lower viable cell counts in the mutant strain tested exposed to excess zinc, consistent with this hypothesis. A stochastic model simulation demonstrated considerable fluctuations in the cellular levels of the ZntA exporter protein, reinforcing this proposal. We hypothesize that maintaining population heterogeneity could be a bet-hedging response allowing a population of cells to survive in varied and fluctuating environments. PMID:25808337

  17. LDL particle heterogeneity, and its association with other established cardiovascular risk factors in a young Indian industrial population

    PubMed Central

    Lakshmy, Ramakrishnan; Dorairaj, Prabhakaran; Tarik, Mohamad; Gupta, Ruby; Reddy, Kolli Srinath

    2012-01-01

    Objective Low density lipoprotein (LDL) particles are heterogeneous in terms of size, density, chemical composition and electric charge with certain particle of LDL being more atherogenic than the others. The present study aimed to look at the LDL particle heterogeneity, particle size and association with other cardiovascular disease (CVD) risk factors in young Indian industrial population. Methodology 600 employees of an industry of Delhi, aged 20-39 years were selected for the study. Data on demographics, individual characteristics associated with major risk factors of CVD, past medical history, clinical and anthropometric profile was collected. Fasting glucose, lipid profile, apolipoprotein (A1, B, and E), lipoprotein (a), high sensitive C-reactive protein (hsCRP) and insulin were estimated. LDL particle size was determined in ethylenediamminetetraacetate (EDTA) plasma by 3% polyacrylamide gel electrophoresis. Result We found a prevalence of small dense LDL phenotype (LDL size ≤ 26.3) in 27.4% of males and 24.0% of females. The mean waist circumference, blood pressure, triglycerides (TAG), cholesterol, hsCRP, apolipoprotein (A1, B and E) and insulin were higher in males whereas mean high density lipoprotein was higher in females. Females also had a significantly higher mean LDL particle diameter as compared to males. Conclusion TAG, physical activity and lipoprotein (a) correlated with small dense LDL in this young Indian population.

  18. Genetic heterogeneity of limb-girdle muscular dystrophy in Amish populations

    SciTech Connect

    Beckmann, J.S.; Allamand, V.; Broux, O.

    1994-09-01

    The autosomal recessive form of limb-girdle muscular dystrophy (LGMD2) is characterized by onset in childhood, progressive weakness predominantly of shoulder, pelvic and trunk muscles with sparing of facial muscles. A gene for LGMD2 was localized to chromosome 15q by Beckmann et al. in 1991 in Isle La Reunion families, subsequently confirmed in Amish families and in Brazilian families where genetic heterogeneity has been demonstrated. Analysis of LGM2 families for recombination events permitted the gene region to be restricted to an interval of about 7 cM defined by flanking markers D15S129 and D15S143. Extended haplotypes were established in the families on the basis of the segregation of multiple markers within this interval. Although the nine northern Indiana Amish families showed linkage of the gene to chromosome 15 markers (maximum lod score of 7.58 at {theta}=0.06 for D15S129 and 12.57 at {theta}=0.046 for D15S143), six large southern Indiana families with LGMD2, clinically indistinguishable from the LGMD2 in northern Indiana, were found to have a disease neither linked to chromosome 15 nor to chromosome 2 where a second localization has been reported. Although these two Indiana Amish LGMD2 kindreds contain some common ancestors and are clinically similar, the LGMD2 appears to be genetically heterogeneous.

  19. Creating targeted initial populations for genetic product searches in heterogeneous markets

    NASA Astrophysics Data System (ADS)

    Foster, Garrett; Turner, Callaway; Ferguson, Scott; Donndelinger, Joseph

    2014-12-01

    Genetic searches often use randomly generated initial populations to maximize diversity and enable a thorough sampling of the design space. While many of these initial configurations perform poorly, the trade-off between population diversity and solution quality is typically acceptable for small-scale problems. Navigating complex design spaces, however, often requires computationally intelligent approaches that improve solution quality. This article draws on research advances in market-based product design and heuristic optimization to strategically construct 'targeted' initial populations. Targeted initial designs are created using respondent-level part-worths estimated from discrete choice models. These designs are then integrated into a traditional genetic search. Two case study problems of differing complexity are presented to illustrate the benefits of this approach. In both problems, targeted populations lead to computational savings and product configurations with improved market share of preferences. Future research efforts to tailor this approach and extend it towards multiple objectives are also discussed.

  20. The Phosphorylation Flow of the Vibrio harveyi Quorum-Sensing Cascade Determines Levels of Phenotypic Heterogeneity in the Population

    PubMed Central

    Plener, Laure; Lorenz, Nicola; Reiger, Matthias; Ramalho, Tiago; Gerland, Ulrich

    2015-01-01

    ABSTRACT Quorum sensing (QS) is a communication process that enables a bacterial population to coordinate and synchronize specific behaviors. The bioluminescent marine bacterium Vibrio harveyi integrates three autoinducer (AI) signals into one quorum-sensing cascade comprising a phosphorelay involving three hybrid sensor kinases: LuxU; LuxO, an Hfq/small RNA (sRNA) switch; and the transcriptional regulator LuxR. Using a new set of V. harveyi mutants lacking genes for the AI synthases and/or sensors, we assayed the activity of the quorum-sensing cascade at the population and single-cell levels, with a specific focus on signal integration and noise levels. We found that the ratios of kinase activities to phosphatase activities of the three sensors and, hence, the extent of phosphorylation of LuxU/LuxO are important not only for the signaling output but also for the degree of noise in the system. The pools of phosphorylated LuxU/LuxO per cell directly determine the amounts of sRNAs produced and, consequently, the copy number of LuxR, generating heterogeneous quorum-sensing activation at the single-cell level. We conclude that the ability to drive the heterogeneous expression of QS-regulated genes in V. harveyi is an inherent feature of the architecture of the QS cascade. IMPORTANCE V. harveyi possesses one of the most complex quorum-sensing (QS) cascades known, using three different autoinducers (AIs) to control the induction of, e.g., bioluminescence, virulence factors, and biofilm and exoprotease production. We constructed various V. harveyi mutants to study the impact of each component and subsystem of the QS signaling cascade on QS activation at the population and single-cell levels. We found that the output was homogeneous only in the presence of all AIs. In the absence of any one AI, QS activation varied from cell to cell, resulting in phenotypic heterogeneity. This study elucidates a molecular design principle which enables a tightly integrated signaling

  1. Combined effects between temporal heterogeneity of water supply, nutrient level, and population density on biomass of four broadly distributed herbaceous species.

    PubMed

    Hagiwara, Yousuke; Kachi, Naoki; Suzuki, Jun-Ichirou

    2012-01-01

    Temporal heterogeneity of water supply affects grassland community productivity and it can interact with nutrient level and intraspecific competition. To understand community responses, the responses of individual species to water heterogeneity must be evaluated while considering the interactions of this heterogeneity with nutrient levels and population density. We compared responses of four herbaceous species grown in monocultures to various combinations of water heterogeneity, nutrient level, and population density: two grasses (Cynodon dactylon and Lolium perenne), a forb (Artemisia princeps), and a legume (Trifolium repens). Treatment effects on shoot and root biomass were analyzed. In all four species, shoot biomass was larger under homogeneous than under heterogeneous water supply. Shoot responses of L. perenne tended to be greater at high nutrient levels. Although root biomass was also larger under homogeneous water supply, effects of water heterogeneity on root biomass were not significant in the grasses. Trifolium repens showed marked root responses, particularly at high population density. Although greater shoot and root growth under homogeneous water supply appears to be a general trend among herbaceous species, our results suggested differences among species could be found in the degree of response to water heterogeneity and its interactions with nutrient level and intraspecific competition. PMID:21327692

  2. Populating the i2b2 database with heterogeneous EMR data: a semantic network approach.

    PubMed

    Mate, Sebastian; Bürkle, Thomas; Köpcke, Felix; Breil, Bernhard; Wullich, Bernd; Dugas, Martin; Prokosch, Hans-Ulrich; Ganslandt, Thomas

    2011-01-01

    In an ongoing effort to share heterogeneous electronic medical record (EMR) data in an i2b2 instance between the University Hospitals Münster and Erlangen for joint cancer research projects, an ontology based system for the mapping of EMR data to a set of common data elements has been developed. The system translates the mappings into local SQL scripts, which are then used to extract, transform and load the facts data from each EMR into the i2b2 database. By using Semantic Web standards, it is the authors' goal to reuse the laboriously compiled "mapping knowledge" in future projects, such as a comprehensive cancer ontology or even a hospital-wide clinical ontology. PMID:21893800

  3. Heterogeneity in protein expression induces metabolic variability in a modeled Escherichia coli population.

    PubMed

    Labhsetwar, Piyush; Cole, John Andrew; Roberts, Elijah; Price, Nathan D; Luthey-Schulten, Zaida A

    2013-08-20

    Stochastic gene expression can lead to phenotypic differences among cells even in isogenic populations growing under macroscopically identical conditions. Here, we apply flux balance analysis in investigating the effects of single-cell proteomics data on the metabolic behavior of an in silico Escherichia coli population. We use the latest metabolic reconstruction integrated with transcriptional regulatory data to model realistic cells growing in a glucose minimal medium under aerobic conditions. The modeled population exhibits a broad distribution of growth rates, and principal component analysis was used to identify well-defined subpopulations that differ in terms of their pathway use. The cells differentiate into slow-growing acetate-secreting cells and fast-growing CO2-secreting cells, and a large population growing at intermediate rates shift from glycolysis to Entner-Doudoroff pathway use. Constraints imposed by integrating regulatory data have a large impact on NADH oxidizing pathway use within the cell. Finally, we find that stochasticity in the expression of only a few genes may be sufficient to capture most of the metabolic variability of the entire population. PMID:23908403

  4. The Heterogeneous Second-Language Population in US Colleges and the Impact on Writing Program Design

    ERIC Educational Resources Information Center

    di Gennaro, Kristen

    2012-01-01

    To effectively address the needs of second language (L2) learners in college writing courses, many postsecondary institutions, especially those located in cities with high concentrations of immigrants, offer college-level courses for L2 students. Such courses include noncredit English language courses in an intensive English program, developmental…

  5. Organizational Factors Affecting the Continuation of an Instructional Innovation for Heterogeneous Populations.

    ERIC Educational Resources Information Center

    Dahl, Rene Fukuhara

    This paper investigates the elementary school principal's role in helping to sustain implementation of a complex math and science program designed to foster the development of higher order thinking skills, particularly for language minority students. The study predicted a positive relationship between coordination and program continuation; if the…

  6. A Revised Version of the Norwegian Adaptation of the Test Anxiety Inventory in a Heterogeneous Population

    ERIC Educational Resources Information Center

    Oktedalen, Tuva; Hagtvet, Knut A.

    2011-01-01

    Confirmatory factor analysis and Multiple Indicators, Multiple Causes (MIMIC) modeling were employed to investigate psychometric properties of a revised adaptation of the Norwegian version of the Test Anxiety Inventory (RTAIN) in a sample of 456 students. The study supported the Norwegian version as a useful inventory for measuring the components…

  7. Heterogeneous road networks have no apparent effect on the genetic structure of small mammal populations.

    PubMed

    Grilo, Clara; Del Cerro, Irene; Centeno-Cuadros, Alejandro; Ramiro, Victor; Román, Jacinto; Molina-Vacas, Guillem; Fernández-Aguilar, Xavier; Rodríguez, Juan; Porto-Peter, Flávia; Fonseca, Carlos; Revilla, Eloy; Godoy, José A

    2016-09-15

    Roads are widely recognized to represent a barrier to individual movements and, conversely, verges can act as potential corridors for the dispersal of many small mammals. Both barrier and corridor effects should generate a clear spatial pattern in genetic structure. Nevertheless, the effect of roads on the genetic structure of small mammal populations still remains unclear. In this study, we examine the barrier effect that different road types (4-lane highway, 2-lane roads and single-lane unpaved roads) may have on the population genetic structure of three species differing in relevant life history traits: southern water vole Arvicola sapidus, the Mediterranean pine vole Microtus duodecimcostatus and the Algerian mouse Mus spretus. We also examine the corridor effect of highway verges on the Mediterranean pine vole and the Algerian mouse. We analysed the population structure through pairwise estimates of FST among subpopulations bisected by roads, identified genetic clusters through Bayesian assignment approaches, and used simple and partial Mantel tests to evaluate the relative barrier or corridor effect of roads. No strong evidences were found for an effect of roads on population structure of these three species. The barrier effect of roads seems to be site-specific and no corridor effect of verges was found for the pine vole and Algerian mouse populations. The lack of consistent results among species and for each road type lead us to believe that the ability of individual dispersers to use those crossing structures or the habitat quality in the highway verges may have a relatively higher influence on gene flow among populations than the presence of crossing structures per se. Further research should include microhabitat analysis and the estimates of species abundance to understand the mechanisms that underlie the genetic structure observed at some sites. PMID:27219505

  8. 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…

  9. Profiles 1987-88. Detailed Analyses of the Foreign Student Population.

    ERIC Educational Resources Information Center

    Zikopoulos, Marianthi, Ed.

    Detailed, indepth information is provided on the characteristics of individual foreign students to complement the annual report "Open Doors," which reports data on single characteristics of the foreign student population. Data are provided about subgroups of the foreign student population (e.g., the proportion of graduates versus undergraduates…

  10. A heterogeneous population code for elapsed time in rat medial agranular cortex

    PubMed Central

    Matell, Matthew S.; Shea-Brown, Eric; Gooch, Cindy; Wilson, A. George; Rinzel, John

    2010-01-01

    The neural mechanisms underlying the temporal control of behavior are largely unknown. Here we recorded from the medial agranular cortex in rats trained to respond on a temporal production procedure for probabilistically available food reward. Due to variability in estimating the time of food availability, robust responding typically bracketed the expected duration, starting some time before and ending some time after the signaled delay. This response period provided an analytic “steady-state” window during which the subject actively timed their behavior. Remarkably, during these response periods, a variety of firing patterns were seen which could be broadly described as ramps, peaks, and dips, with different slopes, directions, and times at which maxima or minima occur. Regularized linear discriminant analysis indicated that these patterns provided sufficiently reliable information to discriminate the elapsed duration of responding within these response periods. Modeling this across neuron variability showed that the utilization of ramps, dips, and peaks with different slopes and minimal/maximal rates at different times led to a substantial improvement in temporal prediction errors, suggesting that heterogeneity in the neural representation of elapsed time may facilitate temporally controlled behavior. PMID:21319888

  11. Human factors involvement in bringing the power of AI to a heterogeneous user population

    NASA Technical Reports Server (NTRS)

    Czerwinski, Mary; Nguyen, Trung

    1994-01-01

    The Human Factors involvement in developing COMPAQ QuickSolve, an electronic problem-solving and information system for Compaq's line of networked printers, is described. Empowering customers with expert system technology so they could solve advanced networked printer problems on their own was a major goal in designing this system. This process would minimize customer down-time, reduce the number of phone calls to the Compaq Customer Support Center, improve customer satisfaction, and, most importantly, differentiate Compaq printers in the marketplace by providing the best, and most technologically advanced, customer support. This represents a re-engineering of Compaq's customer support strategy and implementation. In its first generation system, SMART, the objective was to provide expert knowledge to Compaq's help desk operation to more quickly and correctly answer customer questions and problems. QuickSolve is a second generation system in that customer support is put directly in the hands of the consumers. As a result, the design of QuickSolve presented a number of challenging issues. Because the produce would be used by a diverse and heterogeneous set of users, a significant amount of human factors research and analysis was required while designing and implementing the system. Research that shaped the organization and design of the expert system component as well.

  12. All different, all equal: Evidence of a heterogeneous Neolithic population at the Bom Santo Cave necropolis (Portugal).

    PubMed

    Gonçalves, D; Granja, R; Alves-Cardoso, F; Carvalho, A F

    2016-06-01

    The objective of this paper was to contribute to the discussion regarding the socio-political organization of south-western Iberian Middle Neolithic populations. To that end, the preservation and distribution of human remains and the dispersion of grave goods within two rooms of the Bom Santo Cave (Rooms A and B) were investigated and combined with genetic and isotopic data previously published. Grave goods distribution and skeletal analyses highlighted an important diversity in terms of funerary practices thus corroborating data from ancient DNA and Sr/O isotopic analyses that suggested a great genetic and geographic diversity. Grave goods presented an uneven spatial distribution and were made of raw materials from different sources and using different pottery manufacturing styles albeit typologically homogeneous. The preservation and distribution of human remains suggested that Room A was mainly used for secondary depositions while Room B was used for both primary and secondary depositions. No link between the two rooms was found since remains from the same individuals were apparently exclusive of one room or another. The results suggest that this society presented substantial inner genetic, social and geographical heterogeneity. Most probably, this was due to the presence of distinct but coeval groups in the cave that shared a larger-scale social identity (as in "segmentary societies") or, less likely, to the presence of one single, but internally heterogeneous society (as in fully sedentary societies) that assimilated foreigners. PMID:27016326

  13. Unexpected genetic heterogeneity for primary ciliary dyskinesia in the Irish Traveller population.

    PubMed

    Casey, Jillian P; McGettigan, Paul A; Healy, Fiona; Hogg, Claire; Reynolds, Alison; Kennedy, Breandan N; Ennis, Sean; Slattery, Dubhfeasa; Lynch, Sally A

    2015-02-01

    We present a study of five children from three unrelated Irish Traveller families presenting with primary ciliary dyskinesia (PCD). As previously characterized disorders in the Irish Traveller population are caused by common homozygous mutations, we hypothesised that all three PCD families shared the same recessive mutation. However, exome sequencing showed that there was no pathogenic homozygous mutation common to all families. This finding was supported by histology, which showed that each family has a different type of ciliary defect; transposition defect (family A), nude epithelium (family B) and absence of inner and outer dynein arms (family C). Therefore, each family was analysed independently using homozygosity mapping and exome sequencing. The affected siblings in family A share a novel 1 bp duplication in RSPH4A (NM_001161664.1:c.166dup; p.Arg56Profs*11), a radial-spoke head protein involved in ciliary movement. In family B, we identified three candidate genes (CCNO, KCNN3 and CDKN1C), with a 5-bp duplication in CCNO (NM_021147.3:c.258_262dup; p.Gln88Argfs*8) being the most likely cause of ciliary aplasia. This is the first study to implicate CCNO, a DNA repair gene reported to be involved in multiciliogenesis, in PCD. In family C, we identified a ∼3.5-kb deletion in DYX1C1, a neuronal migration gene previously associated with PCD. This is the first report of a disorder in the relatively small Irish Traveller population to be caused by >1 disease gene. Our study identified at least three different PCD genes in the Irish Traveller population, highlighting that one cannot always assume genetic homogeneity, even in small consanguineous populations. PMID:24824133

  14. Cooperative action of coherent groups in broadly heterogeneous populations of interacting chemical oscillators

    PubMed Central

    Mikhailov, A. S.; Zanette, D. H.; Zhai, Y. M.; Kiss, I. Z.; Hudson, J. L.

    2004-01-01

    We present laboratory experiments on the effects of global coupling in a population of electrochemical oscillators with a multimodal frequency distribution. The experiments show that complex collective signals are generated by this system through spontaneous emergence and joint operation of coherently acting groups representing hierarchically organized resonant clusters. Numerical simulations support these experimental findings. Our results suggest that some forms of internal self-organization, characteristic for complex multiagent systems, are already possible in simple chemical systems. PMID:15263084

  15. Unique spectral markers discern recurrent Glioblastoma cells from heterogeneous parent population

    PubMed Central

    Kaur, Ekjot; Sahu, Aditi; Hole, Arti R.; Rajendra, Jacinth; Chaubal, Rohan; Gardi, Nilesh; Dutt, Amit; Moiyadi, Aliasgar; Krishna, C. Murali; Dutt, Shilpee

    2016-01-01

    An inability to discern resistant cells from bulk tumour cell population contributes to poor prognosis in Glioblastoma. Here, we compared parent and recurrent cells generated from patient derived primary cultures and cell lines to identify their unique molecular hallmarks. Although morphologically similar, parent and recurrent cells from different samples showed variable biological properties like proliferation and radiation resistance. However, total RNA-sequencing revealed transcriptional landscape unique to parent and recurrent populations. These data suggest that global molecular differences but not individual biological phenotype could differentiate parent and recurrent cells. We demonstrate that Raman Spectroscopy a label-free, non-invasive technique, yields global information about biochemical milieu of recurrent and parent cells thus, classifying them into distinct clusters based on Principal-Component-Analysis and Principal-Component-Linear-Discriminant-Analysis. Additionally, higher lipid related spectral peaks were observed in recurrent population. Importantly, Raman spectroscopic analysis could further classify an independent set of naïve primary glioblastoma tumour tissues into non-responder and responder groups. Interestingly, spectral features from the non-responder patient samples show a considerable overlap with the in-vitro generated recurrent cells suggesting their similar biological behaviour. This feasibility study necessitates analysis of a larger cohort of naïve primary glioblastoma samples to fully envisage clinical utility of Raman spectroscopy in predicting therapeutic response. PMID:27221528

  16. A role for E-cadherin in ensuring cohesive migration of a heterogeneous population of non-epithelial cells

    PubMed Central

    Campbell, Kyra; Casanova, Jordi

    2015-01-01

    Collective cell migration is a key process underlying the morphogenesis of many organs as well as tumour invasion, which very often involves heterogeneous cell populations. Here we investigated how such populations can migrate cohesively in the Drosophila posterior midgut, comprised of epithelial and mesenchymal cells and show a novel role for the epithelial adhesion molecule E-cadherin (E-Cad) in mesenchymal cells. Despite a lack of junctions at the ultrastructure level, reducing E-Cad levels causes mesenchymal cells to detach from one another and from neighbouring epithelial cells; as a result, coordination between the two populations is lost. Moreover, Bazooka and recycling mechanisms are also required for E-Cad accumulation in mesenchymal cells. These results indicate an active role for E-Cad in mediating cohesive and ordered migration of non-epithelial cells, and discount the notion of E-Cad as just an epithelial feature that has to be switched off to enable migration of mesenchymal cells. PMID:26272476

  17. Computing Ro in a population with heterogeneity in sexual activity and proportionate mixing using a STM-solver

    NASA Astrophysics Data System (ADS)

    Gutierrez A., Natalia A.

    2014-06-01

    A model to determinate the reproductive basic number, detonated Ro, for the case of population with heterogeneity in sexual activity and proportionate mixing is solved using computer algebra and SMT solvers. Specifically Maple and Z3 were used. The code for the solution of the model was written in Z3-Python, but it can also be played by Z3-SMT-Lib. Ro represents an algebraic synthesis of every epidemiological parameter. Numerical simulations were done to prove the effectiveness of the model and the code. The algebraic structure of Ro suggests the possible control measurements that should be implemented to avoid the propagation of the sexual transmitted diseases. The obtained results are important on the computational epidemiology field. As a future investigation, it is suggested to apply the STM solvers to analyze models for other kinds of epidemic diseases.

  18. Population Heterogeneity of Salmonella enterica Serotype Typhimurium Resulting from Phase Variation of the lpf Operon In Vitro and In Vivo

    PubMed Central

    Kingsley, Robert A.; Weening, Eric H.; Keestra, A. Marijke; Bäumler, Andreas J.

    2002-01-01

    The lpf fimbrial operon oscillates between phase ON and phase OFF expression states, thereby generating heterogeneity within S. enterica serotype Typhimurium populations with regard to expression of long polar fimbrial antigens. To determine whether the proportion of lpf phase variants changes with growth conditions, the lpf phase ON content of cultures was determined after in vitro and in vivo passage. After passage in Luria-Bertani (LB) broth for 120 generations, 96% of cells in a serotype Typhimurium culture carried the lpf operon in the phase ON expression state, regardless of the phase ON/OFF ratio in the inoculum. In contrast, a culture passaged on LB agar plates for 500 generations contained approximately 2% lpf phase ON cells. Differences in the lpf phase ON content of cultures passaged in broth and on plates were not caused by an outgrowth of lpf phase ON or lpf phase OFF cells, since deletion of lpf biosynthesis genes did not alter the phase ON/OFF ratio attained after passage. Instead, growth in LB broth resulted in a eightfold increase in the phase OFF-to-ON transition frequency and a decrease of the lpf phase ON-to-OFF transition frequency by a factor of 150 compared to growth on LB agar plates. After infection of naïve CBA/J mice with an lpf phase ON culture of serotype Typhimurium, the proportion of lpf phase ON cells continuously decreased over time, regardless of whether the strain carried intact fimbrial biosynthesis genes. These data suggest that elaboration of fimbriae does not have a major influence on the population heterogeneity produced by phase variation of the lpf operon in naïve mice. PMID:11948147

  19. Population heterogeneity of Salmonella enterica serotype Typhimurium resulting from phase variation of the lpf operon in vitro and in vivo.

    PubMed

    Kingsley, Robert A; Weening, Eric H; Keestra, A Marijke; Bäumler, Andreas J

    2002-05-01

    The lpf fimbrial operon oscillates between phase ON and phase OFF expression states, thereby generating heterogeneity within S. enterica serotype Typhimurium populations with regard to expression of long polar fimbrial antigens. To determine whether the proportion of lpf phase variants changes with growth conditions, the lpf phase ON content of cultures was determined after in vitro and in vivo passage. After passage in Luria-Bertani (LB) broth for 120 generations, 96% of cells in a serotype Typhimurium culture carried the lpf operon in the phase ON expression state, regardless of the phase ON/OFF ratio in the inoculum. In contrast, a culture passaged on LB agar plates for 500 generations contained approximately 2% lpf phase ON cells. Differences in the lpf phase ON content of cultures passaged in broth and on plates were not caused by an outgrowth of lpf phase ON or lpf phase OFF cells, since deletion of lpf biosynthesis genes did not alter the phase ON/OFF ratio attained after passage. Instead, growth in LB broth resulted in a eightfold increase in the phase OFF-to-ON transition frequency and a decrease of the lpf phase ON-to-OFF transition frequency by a factor of 150 compared to growth on LB agar plates. After infection of naïve CBA/J mice with an lpf phase ON culture of serotype Typhimurium, the proportion of lpf phase ON cells continuously decreased over time, regardless of whether the strain carried intact fimbrial biosynthesis genes. These data suggest that elaboration of fimbriae does not have a major influence on the population heterogeneity produced by phase variation of the lpf operon in naïve mice. PMID:11948147

  20. Heterogeneous genetic structure in a Fagus crenata population in an old-growth beech forest revealed by microsatellite markers.

    PubMed

    Asuka, Y; Tomaru, N; Nisimura, N; Tsumura, Y; Yamamoto, S

    2004-05-01

    The within-population genetic structure of Fagus crenata in a 4-ha plot (200 x 200 m) of an old-growth beech forest was analysed using microsatellite markers. To assess the genetic structure, Moran's I spatial autocorrelation coefficient was calculated. Correlograms of Moran's I showed significant positive values less than 0.100 for short-distance classes, indicating weak genetic structure. The genetic structure within the population is created by limited seed dispersal, and is probably weakened by overlapping seed shadow, secondary seed dispersal, extensive pollen flow and the thinning process. Genetic structure was detected in a western subplot of 50 x 200 m with immature soils and almost no dwarf bamboos (Sasa spp.), where small and intermediate-sized individuals were distributed in aggregations with high density because of successful regeneration. By contrast, genetic structure was not found in an eastern subplot of the same size with mature soils and Sasa cover, where successful regeneration was prevented, and the density of the small and intermediate-sized individuals was low. Moreover, genetic structure of individuals in a small-size class (diameter at breast height < 12 cm) was more obvious than in a large-size class (diameter at breast height >/= 12 cm). The apparent genetic structure detected in the 4-ha plot was therefore probably the result of the structure in the western portion of the plot and in small and intermediate-sized individuals that successfully regenerated under the favourable environment. The heterogeneity in genetic structure presumably reflects variation in the density that should be affected by differences in regeneration dynamics associated with heterogeneity in environmental conditions. PMID:15078459

  1. CCAST: a model-based gating strategy to isolate homogeneous subpopulations in a heterogeneous population of single cells.

    PubMed

    Anchang, Benedict; Do, Mary T; Zhao, Xi; Plevritis, Sylvia K

    2014-07-01

    A model-based gating strategy is developed for sorting cells and analyzing populations of single cells. The strategy, named CCAST, for Clustering, Classification and Sorting Tree, identifies a gating strategy for isolating homogeneous subpopulations from a heterogeneous population of single cells using a data-derived decision tree representation that can be applied to cell sorting. Because CCAST does not rely on expert knowledge, it removes human bias and variability when determining the gating strategy. It combines any clustering algorithm with silhouette measures to identify underlying homogeneous subpopulations, then applies recursive partitioning techniques to generate a decision tree that defines the gating strategy. CCAST produces an optimal strategy for cell sorting by automating the selection of gating markers, the corresponding gating thresholds and gating sequence; all of these parameters are typically manually defined. Even though CCAST is optimized for cell sorting, it can be applied for the identification and analysis of homogeneous subpopulations among heterogeneous single cell data. We apply CCAST on single cell data from both breast cancer cell lines and normal human bone marrow. On the SUM159 breast cancer cell line data, CCAST indicates at least five distinct cell states based on two surface markers (CD24 and EPCAM) and provides a gating sorting strategy that produces more homogeneous subpopulations than previously reported. When applied to normal bone marrow data, CCAST reveals an efficient strategy for gating T-cells without prior knowledge of the major T-cell subtypes and the markers that best define them. On the normal bone marrow data, CCAST also reveals two major mature B-cell subtypes, namely CD123+ and CD123- cells, which were not revealed by manual gating but show distinct intracellular signaling responses. More generally, the CCAST framework could be used on other biological and non-biological high dimensional data types that are

  2. Stage-dependent responses to emergent habitat heterogeneity: consequences for a predatory insect population in a coffee agroecosystem

    PubMed Central

    Liere, Heidi; Perfecto, Ivette; Vandermeer, John

    2014-01-01

    Interactions among members of biological communities can create spatial patterns that effectively generate habitat heterogeneity for other members in the community, and this heterogeneity might be crucial for their persistence. For example, stage-dependent vulnerability of a predatory lady beetle to aggression of the ant, Azteca instabilis, creates two habitat types that are utilized differently by the immature and adult life stages of the beetle. Due to a mutualistic association between A. instabilis and the hemipteran Coccus viridis – which is A. orbigera main prey in the area – only plants around ant nests have high C. viridis populations. Here, we report on a series of surveys at three different scales aimed at detecting how the presence and clustered distribution of ant nests affect the distribution of the different life stages of this predatory lady beetle in a coffee farm in Chiapas, Mexico. Both beetle adults and larvae were more abundant in areas with ant nests, but adults were restricted to the peripheries of highest ant activity and outside the reach of coffee bushes containing the highest densities of lady beetle larvae. The abundance of adult beetles located around trees with ants increased with the size of the ant nest clusters but the relationship is not significant for larvae. Thus, we suggest that A. orbigera undergoes an ontogenetic niche shift, not through shifting prey species, but through stage-specific vulnerability differences against a competitor that renders areas of abundant prey populations inaccessible for adults but not for larvae. Together with evidence presented elsewhere, this study shows how an important predator is not only dependent on the existence of two qualitatively distinct habitat types, but also on the spatial distribution of these habitats. We suggest that this dependency arises due to the different responses that the predator's life stages have to this emergent spatial pattern. PMID:25473473

  3. HETEROGENEOUS DOPAMINE POPULATIONS PROJECT TO SPECIFIC SUBREGIONS OF THE PRIMATE AMYGDALA

    PubMed Central

    CHO, Y. T.; FUDGE, J. L.

    2010-01-01

    Amygdala dysfunction has been reported among patients with various psychiatric disorders, and dopamine is critical to the amygdala's ability to mediate fear conditioning. Recent work indicates that the midbrain dopaminergic neurons have heterogeneous receptor and membrane channel profiles, as well as differential physiologic responses to discrete stimuli. To begin understanding how dopamine affects amygdala physiology and pathology in higher primates, we mapped the inputs from the midbrain dopaminergic neurons to various amygdala nuclei in the monkey using retrograde and anterograde tracing techniques, and single and double immunofluorescence histochemistry for tracer and tyrosine hydroxylase, a dopamine marker. Our results show that the primate amygdala as a whole receives broad input, mostly from the dorsal tier of the substantia nigra, pars compacta, and the A8-retrorubral field. Input from the A10-ventral tegmental area, while present, was less prominent. These results differ from data in the rat, where the midline A10-ventral tegmental area is a major source of dopamine to the amygdala “mesolimbic” pathway. Both the “amygdala proper” and the “extended amygdala” receive the majority of their input from the dorsal tier of the substantia nigra and A8-retrorubral field, but the extended amygdala receives additional modest input from the ventral tier. In addition, the “extended amygdala” structures have a denser input than the “amygdala proper,” with the exception of the lateral core of the central nucleus, which receives no input. Our anterograde studies confirm these findings, and revealed fine, diffuse terminal fibers in the amygdala proper, but a denser network of fibers in the extended amygdala outside the lateral core of the central nucleus. These results indicate that the entire extent of the dorsal tier beyond the A10-ventral tegmental area may regulate the amygdala in primates, and subsequently serve as a source of dysfunction in

  4. Allelic heterogeneity in NCF2 associated with systemic lupus erythematosus (SLE) susceptibility across four ethnic populations

    PubMed Central

    Kim-Howard, Xana; Sun, Celi; Molineros, Julio E.; Maiti, Amit K.; Chandru, Hema; Adler, Adam; Wiley, Graham B.; Kaufman, Kenneth M.; Kottyan, Leah; Guthridge, Joel M.; Rasmussen, Astrid; Kelly, Jennifer; Sánchez, Elena; Raj, Prithvi; Li, Quan-Zhen; Bang, So-Young; Lee, Hye-Soon; Kim, Tae-Hwan; Kang, Young Mo; Suh, Chang-Hee; Chung, Won Tae; Park, Yong-Beom; Choe, Jung-Yoon; Shim, Seung Cheol; Lee, Shin-Seok; Han, Bok-Ghee; Olsen, Nancy J.; Karp, David R.; Moser, Kathy; Pons-Estel, Bernardo A.; Wakeland, Edward K.; James, Judith A.; Harley, John B.; Bae, Sang-Cheol; Gaffney, Patrick M.; Alarcón-Riquelme, Marta; Looger, Loren L.; Nath, Swapan K.; Acevedo, Eduardo; Acevedo, Eduardo; La Torre, Ignacio García-De; Maradiaga-Ceceña, Marco A.; Cardiel, Mario H.; Esquivel-Valerio, Jorge A.; Rodriguez-Amado, Jacqueline; Moctezuma, José Francisco; Miranda, Pedro; Perandones, Carlos; Aires, Buenos; Castel, Cecilia; Laborde, Hugo A.; Alba, Paula; Musuruana, Jorge; Goecke, Annelise; Foster, Carola; Orozco, Lorena; Baca, Vicente

    2014-01-01

    Recent reports have associated NCF2, encoding a core component of the multi-protein NADPH oxidase (NADPHO), with systemic lupus erythematosus (SLE) susceptibility in individuals of European ancestry. To identify ethnicity-specific and -robust variants within NCF2, we assessed 145 SNPs in and around the NCF2 gene in 5325 cases and 21 866 controls of European-American (EA), African-American (AA), Hispanic (HS) and Korean (KR) ancestry. Subsequent imputation, conditional, haplotype and bioinformatic analyses identified seven potentially functional SLE-predisposing variants. Association with non-synonymous rs17849502, previously reported in EA, was detected in EA, HS and AA (PEA = 1.01 × 10−54, PHS = 3.68 × 10−10, PAA = 0.03); synonymous rs17849501 was similarly significant. These SNPs were monomorphic in KR. Novel associations were detected with coding variants at rs35937854 in AA (PAA = 1.49 × 10−9), and rs13306575 in HS and KR (PHS = 7.04 × 10−7, PKR = 3.30 × 10−3). In KR, a 3-SNP haplotype was significantly associated (P = 4.20 × 10−7), implying that SLE predisposing variants were tagged. Significant SNP–SNP interaction (P = 0.02) was detected between rs13306575 and rs17849502 in HS, and a dramatically increased risk (OR = 6.55) with a risk allele at each locus. Molecular modeling predicts that these non-synonymous mutations could disrupt NADPHO complex assembly. The risk allele of rs17849501, located in a conserved transcriptional regulatory region, increased reporter gene activity, suggesting in vivo enhancer function. Our results not only establish allelic heterogeneity within NCF2 associated with SLE, but also emphasize the utility of multi-ethnic cohorts to identify predisposing variants explaining additional phenotypic variance (‘missing heritability’) of complex diseases like SLE. PMID:24163247

  5. Allelic heterogeneity in NCF2 associated with systemic lupus erythematosus (SLE) susceptibility across four ethnic populations.

    PubMed

    Kim-Howard, Xana; Sun, Celi; Molineros, Julio E; Maiti, Amit K; Chandru, Hema; Adler, Adam; Wiley, Graham B; Kaufman, Kenneth M; Kottyan, Leah; Guthridge, Joel M; Rasmussen, Astrid; Kelly, Jennifer; Sánchez, Elena; Raj, Prithvi; Li, Quan-Zhen; Bang, So-Young; Lee, Hye-Soon; Kim, Tae-Hwan; Kang, Young Mo; Suh, Chang-Hee; Chung, Won Tae; Park, Yong-Beom; Choe, Jung-Yoon; Shim, Seung Cheol; Lee, Shin-Seok; Han, Bok-Ghee; Olsen, Nancy J; Karp, David R; Moser, Kathy; Pons-Estel, Bernardo A; Wakeland, Edward K; James, Judith A; Harley, John B; Bae, Sang-Cheol; Gaffney, Patrick M; Alarcón-Riquelme, Marta; Looger, Loren L; Nath, Swapan K

    2014-03-15

    Recent reports have associated NCF2, encoding a core component of the multi-protein NADPH oxidase (NADPHO), with systemic lupus erythematosus (SLE) susceptibility in individuals of European ancestry. To identify ethnicity-specific and -robust variants within NCF2, we assessed 145 SNPs in and around the NCF2 gene in 5325 cases and 21 866 controls of European-American (EA), African-American (AA), Hispanic (HS) and Korean (KR) ancestry. Subsequent imputation, conditional, haplotype and bioinformatic analyses identified seven potentially functional SLE-predisposing variants. Association with non-synonymous rs17849502, previously reported in EA, was detected in EA, HS and AA (P(EA) = 1.01 × 10(-54), PHS = 3.68 × 10(-10), P(AA) = 0.03); synonymous rs17849501 was similarly significant. These SNPs were monomorphic in KR. Novel associations were detected with coding variants at rs35937854 in AA (PAA = 1.49 × 10(-9)), and rs13306575 in HS and KR (P(HS) = 7.04 × 10(-7), P(KR) = 3.30 × 10(-3)). In KR, a 3-SNP haplotype was significantly associated (P = 4.20 × 10(-7)), implying that SLE predisposing variants were tagged. Significant SNP-SNP interaction (P = 0.02) was detected between rs13306575 and rs17849502 in HS, and a dramatically increased risk (OR = 6.55) with a risk allele at each locus. Molecular modeling predicts that these non-synonymous mutations could disrupt NADPHO complex assembly. The risk allele of rs17849501, located in a conserved transcriptional regulatory region, increased reporter gene activity, suggesting in vivo enhancer function. Our results not only establish allelic heterogeneity within NCF2 associated with SLE, but also emphasize the utility of multi-ethnic cohorts to identify predisposing variants explaining additional phenotypic variance ('missing heritability') of complex diseases like SLE. PMID:24163247

  6. Population and habitat dynamics of the white-footed mouse (Peromyscus leucopus) in a heterogeneous forest

    SciTech Connect

    Ormiston, B.G.

    1984-07-01

    Movements and demography of white-footed mice (Peromyscus leucopus) were determined by live-trapping and radiotelemetry in contiguous upland and lowland forest habitat to assess the extent of variation in local habitat distribution due to season, age, and sex factors. Mice were marked and recaptured monthly in 1980 and 1981 from April through December on a continuous 20 ha trapping grid, thus yielding 1486 captures of 397 individuals. Locations and activity of 43 mice were determined by radiotracking. Various measures of habitat suitability, including adult density, sex ratio, reproduction, persistence, home range size, and immigration, indicated a seasonal cycle of habitat suitability. Upland habitat appeared better for overwintering, and lowland habitat was superior relative to the upland from June through October. Tendencies for breeding females to be restricted to lowland, and for lowland males to display greater mean body weights and smaller home range sizes than upland males, were attributed to greater food availability in the lowland over this period. Individual P. leucopus use local habitats opportunistically, but variations in habitat distribution between the age- and sex-classes of the population noted during the breeding season suggest that local habitats provide a spatial framework for behavioral population regulation in P. leucopus. 49 references, 5 figures, 10 tables.

  7. Population Heterogeneity in the Salience of Multiple Risk Factors for Adolescent Delinquency

    PubMed Central

    Lanza, Stephanie T.; Cooper, Brittany R.; Bray, Bethany C.

    2014-01-01

    Purpose To present mixture regression analysis as an alternative to more standard regression analysis for predicting adolescent delinquency. We demonstrate how mixture regression analysis allows for the identification of population subgroups defined by the salience of multiple risk factors. Methods We identified population subgroups (i.e., latent classes) of individuals based on their coefficients in a regression model predicting adolescent delinquency from eight previously established risk indices drawn from the community, school, family, peer, and individual levels. The study included N = 37,763 tenth-grade adolescents who participated in the Communities that Care Youth Survey. Standard, zero-inflated, and mixture Poisson and negative binomial regression models are considered. Results Standard and mixture negative binomial regression models are selected as optimal. The five-class regression model is interpreted based on the class-specific regression coefficients, indicating that risk factors have varying salience across classes of adolescents. Conclusions Standard regression shows that all risk factors are significantly associated with delinquency. Mixture regression provides more nuanced information, suggesting a unique set of risk factors that are salient for different subgroups of adolescents. Implications for the design of subgroup-specific interventions are discussed. PMID:24231260

  8. Single nucleotide polymorphism analysis reveals heterogeneity within a seedling tree population of a polyembryonic mango cultivar.

    PubMed

    Winterhagen, Patrick; Wünsche, Jens-Norbert

    2016-05-01

    Within a polyembryonic mango seedling tree population, the genetic background of individuals should be identical because vigorous plants for cultivation are expected to develop from nucellar embryos representing maternal clones. Due to the fact that the mango cultivar 'Hôi' is assigned to the polyembryonic ecotype, an intra-cultivar variability of ethylene receptor genes was unexpected. Ethylene receptors in plants are conserved, but the number of receptors or receptor isoforms is variable regarding different plant species. However, it is shown here that the ethylene receptor MiETR1 is present in various isoforms within the mango cultivar 'Hôi'. The investigation of single nucleotide polymorphisms revealed that different MiETR1 isoforms can not be discriminated simply by individual single nucleotide exchanges but by the specific arrangement of single nucleotide polymorphisms at certain positions in the exons of MiETR1. Furthermore, an MiETR1 isoform devoid of introns in the genomic sequence was identified. The investigation demonstrates some limitations of high resolution melting and ScreenClust analysis and points out the necessity of sequencing to identify individual isoforms and to determine the variability within the tree population. PMID:27093244

  9. Layered Alginate Constructs: A Platform for Co-culture of Heterogeneous Cell Populations.

    PubMed

    Sharma, Poonam; Twomey, Julianne D; Patkin, Michelle; Hsieh, Adam H

    2016-01-01

    Many load bearing tissues possess structurally and functionally distinct regions, typically accompanied by different cell phenotypes with differential mechanosensing characteristics. Engineering and analysis of these tissue types remain a challenge. Layered hydrogel constructs provide an opportunity for investigating the interactions among multiple cell populations within single constructs. Alginate hydrogels are both biocompatible and allow for easy isolation of cells after experimentation. Here, we describe a method for the development of small sized dual layered alginate hydrogel discs. This process maintains high cell viability of human mesenchymal stem cells during the formation process and these layered discs can withstand unconfined cyclic compression, commonly used for stimulation of hMSCs undergoing chondrogenesis. These layered constructs can potentially be scaled up to include additional levels, and also be used to segregate cell populations initially after layering. This dual layer alginate hydrogel culture platform can be used for many different applications including engineering and analysis of cells of load bearing tissues and co-cultures of other cell types. PMID:27583983

  10. Texas Community Colleges and Characteristics of a Growing Undocumented Student Population

    ERIC Educational Resources Information Center

    Jauregui, John A.; Slate, John R.; Brown, Michelle Stallone

    2008-01-01

    In this study, the researchers examine the undocumented student population in Texas community colleges. The data indicate steady yearly increases in the number of undocumented students and in their percentage of the total student enrollment. The relationships between undocumented student enrollment, college size, and overall Hispanic student…

  11. Grouped to Achieve: Are There Benefits to Assigning Students to Heterogeneous Cooperative Learning Groups Based on Pre-Test Scores?

    NASA Astrophysics Data System (ADS)

    Werth, Arman Karl

    Cooperative learning has been one of the most widely used instructional practices around the world since the early 1980's. Small learning groups have been in existence since the beginning of the human race. These groups have grown in their variance and complexity overtime. Classrooms are getting more diverse every year and instructors need a way to take advantage of this diversity to improve learning. The purpose of this study was to see if heterogeneous cooperative learning groups based on student achievement can be used as a differentiated instructional strategy to increase students' ability to demonstrate knowledge of science concepts and ability to do engineering design. This study includes two different groups made up of two different middle school science classrooms of 25-30 students. These students were given an engineering design problem to solve within cooperative learning groups. One class was put into heterogeneous cooperative learning groups based on student's pre-test scores. The other class was grouped based on random assignment. The study measured the difference between each class's pre-post gains, student's responses to a group interaction form and interview questions addressing their perceptions of the makeup of their groups. The findings of the study were that there was no significant difference between learning gains for the treatment and comparison groups. There was a significant difference between the treatment and comparison groups in student perceptions of their group's ability to stay on task and manage their time efficiently. Both the comparison and treatment groups had a positive perception of the composition of their cooperative learning groups.

  12. Special Populations: Migrant Students with Disabilities; Native Pacific Basin and Native Hawaiian Students with Disabilities. Appendix G.

    ERIC Educational Resources Information Center

    Office of Special Education and Rehabilitative Services (ED), Washington, DC. Div. of Innovation and Development.

    This appendix to the 14th annual report on implementation of the Individuals with Disabilities Education Act contains reports on progress in addressing the needs of two special populations: migrant students with disabilities and Native Pacific Basin and Native Hawaiian students with disabilities. Migrant students with disabilities tend to have…

  13. Improving Achievement for the Growing Latino Population Is Critical to the Nation's Future. Student Achievement Policy Brief #3: Latino Students

    ERIC Educational Resources Information Center

    Kober, Nancy

    2010-01-01

    More than one-fifth of the nation's public school students are Latino. By 2025, the share of Latino children is projected to increase to nearly 3 in 10 school-age children (Fry & Passel, 2009). The fast-growing Latino student population will shape the nation's future, so it is critical that these students are well-prepared for college, careers,…

  14. Coalescent Times and Patterns of Genetic Diversity in Species with Facultative Sex: Effects of Gene Conversion, Population Structure, and Heterogeneity.

    PubMed

    Hartfield, Matthew; Wright, Stephen I; Agrawal, Aneil F

    2016-01-01

    Many diploid organisms undergo facultative sexual reproduction. However, little is currently known concerning the distribution of neutral genetic variation among facultative sexual organisms except in very simple cases. Understanding this distribution is important when making inferences about rates of sexual reproduction, effective population size, and demographic history. Here we extend coalescent theory in diploids with facultative sex to consider gene conversion, selfing, population subdivision, and temporal and spatial heterogeneity in rates of sex. In addition to analytical results for two-sample coalescent times, we outline a coalescent algorithm that accommodates the complexities arising from partial sex; this algorithm can be used to generate multisample coalescent distributions. A key result is that when sex is rare, gene conversion becomes a significant force in reducing diversity within individuals. This can reduce genomic signatures of infrequent sex (i.e., elevated within-individual allelic sequence divergence) or entirely reverse the predicted patterns. These models offer improved methods for assessing null patterns of molecular variation in facultative sexual organisms. PMID:26584902

  15. Host heterogeneity influences the impact of a non-native disease invasion on populations of a foundation tree species

    USGS Publications Warehouse

    Jules, Erik S.; Carroll, Allyson L.; Garcia, Andrea M.; Steenbock, Christopher M.; Kauffman, Matthew

    2014-01-01

     P. lateralis causes profound impacts to population structure and the invasion outcome will be governed by the heterogeneity found in host size and location. Models of disease invasion will require an understanding of how heterogeneity influences spread dynamics to adequately predict the outcome for host populations.

  16. The unconventional secretion of stress-inducible protein 1 by a heterogeneous population of extracellular vesicles.

    PubMed

    Hajj, Glaucia N M; Arantes, Camila P; Dias, Marcos Vinicios Salles; Roffé, Martín; Costa-Silva, Bruno; Lopes, Marilene H; Porto-Carreiro, Isabel; Rabachini, Tatiana; Lima, Flávia R; Beraldo, Flávio H; Prado, Marco A M; Prado, Marco M A; Linden, Rafael; Martins, Vilma R

    2013-09-01

    The co-chaperone stress-inducible protein 1 (STI1) is released by astrocytes, and has important neurotrophic properties upon binding to prion protein (PrP(C)). However, STI1 lacks a signal peptide and pharmacological approaches pointed that it does not follow a classical secretion mechanism. Ultracentrifugation, size exclusion chromatography, electron microscopy, vesicle labeling, and particle tracking analysis were used to identify three major types of extracellular vesicles (EVs) released from astrocytes with sizes ranging from 20-50, 100-200, and 300-400 nm. These EVs carry STI1 and present many exosomal markers, even though only a subpopulation had the typical exosomal morphology. The only protein, from those evaluated here, present exclusively in vesicles that have exosomal morphology was PrP(C). STI1 partially co-localized with Rab5 and Rab7 in endosomal compartments, and a dominant-negative for vacuolar protein sorting 4A (VPS4A), required for formation of multivesicular bodies (MVBs), impaired EV and STI1 release. Flow cytometry and PK digestion demonstrated that STI1 localized to the outer leaflet of EVs, and its association with EVs greatly increased STI1 activity upon PrP(C)-dependent neuronal signaling. These results indicate that astrocytes secrete a diverse population of EVs derived from MVBs that contain STI1 and suggest that the interaction between EVs and neuronal surface components enhances STI1-PrP(C) signaling. PMID:23543276

  17. Optimizing the warranty period by cuckoo meta-heuristic algorithm in heterogeneous customers' population

    NASA Astrophysics Data System (ADS)

    Roozitalab, Ali; Asgharizadeh, Ezzatollah

    2013-12-01

    Warranty is now an integral part of each product. Since its length is directly related to the cost of production, it should be set in such a way that it would maximize revenue generation and customers' satisfaction. Furthermore, based on the behavior of customers, it is assumed that increasing the warranty period to earn the trust of more customers leads to more sales until the market is saturated. We should bear in mind that different groups of consumers have different consumption behaviors and that performance of the product has a direct impact on the failure rate over the life of the product. Therefore, the optimum duration for every group is different. In fact, we cannot present different warranty periods for various customer groups. In conclusion, using cuckoo meta-heuristic optimization algorithm, we try to find a common period for the entire population. Results with high convergence offer a term length that will maximize the aforementioned goals simultaneously. The study was tested using real data from Appliance Company. The results indicate a significant increase in sales when the optimization approach was applied; it provides a longer warranty through increased revenue from selling, not only reducing profit margins but also increasing it.

  18. A Comprehensive Analysis of Primer IDs to Study Heterogeneous HIV-1 Populations.

    PubMed

    Seifert, David; Di Giallonardo, Francesca; Töpfer, Armin; Singer, Jochen; Schmutz, Stefan; Günthard, Huldrych F; Beerenwinkel, Niko; Metzner, Karin J

    2016-01-16

    Determining the composition of viral populations is becoming increasingly important in the field of medical virology. While recently developed computational tools for viral haplotype analysis allow for correcting sequencing errors, they do not always allow for the removal of errors occurring in the upstream experimental protocol, such as PCR errors. Primer IDs (pIDs) are one method to address this problem by harnessing redundant template resampling for error correction. By using a reference mixture of five HIV-1 strains, we show how pIDs can be useful for estimating key experimental parameters, such as the substitution rate of the PCR process and the reverse transcription (RT) error rate. In addition, we introduce a hidden Markov model for determining the recombination rate of the RT PCR process. We found no strong sequence-specific bias in pID abundances (the same RT efficiencies as compared to commonly used short, specific RT primers) and no effects of pIDs on the estimated distribution of the references viruses. PMID:26711506

  19. Spatial Heterogeneity of Bacterial Populations along an Environmental Gradient at a Shallow Submarine Hydrothermal Vent near Milos Island (Greece)

    PubMed Central

    Sievert, Stefan M.; Brinkhoff, Thorsten; Muyzer, Gerard; Ziebis, Wiebke; Kuever, Jan

    1999-01-01

    The spatial heterogeneity of bacterial populations at a shallow-water hydrothermal vent in the Aegean Sea close to the island of Milos (Greece) was examined at two different times by using acridine orange staining for total cell counts, cultivation-based techniques, and denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA gene fragments. Concurrent with measurements of geochemical parameters, samples were taken along a transect from the center of the vent to the surrounding area. Most-probable-number (MPN) counts of metabolically defined subpopulations generally constituted a minor fraction of the total cell counts; both counting procedures revealed the highest cell numbers in a transition zone from the strongly hydrothermally influenced sediments to normal sedimentary conditions. Total cell counts ranged from 3.2 × 105 cells ml−1 in the water overlying the sediments to 6.4 × 108 cells g (wet weight) of sediment−1. MPN counts of chemolithoautotrophic sulfur-oxidizing bacteria varied between undetectable and 1.4 × 106 cells g−1. MPN counts for sulfate-reducing bacteria and dissimilatory iron-reducing bacteria ranged from 8 to 1.4 × 105 cells g−1 and from undetectable to 1.4 × 106 cells g−1, respectively. DGGE revealed a trend from a diverse range of bacterial populations which were present in approximately equal abundance in the transition zone to a community dominated by few populations close to the center of the vent. Temperature was found to be an important parameter in determining this trend. However, at one sampling time this trend was not discernible, possibly due to storm-induced disturbance of the upper sediment layers. PMID:10473383

  20. High Levels of Heterogeneity in the HIV Cascade of Care across Different Population Subgroups in British Columbia, Canada

    PubMed Central

    Lourenço, Lillian; Colley, Guillaume; Nosyk, Bohdan; Shopin, Dmitry; Montaner, Julio S. G.; Lima, Viviane D.

    2014-01-01

    Background The HIV cascade of care (cascade) is a comprehensive tool which identifies attrition along the HIV care continuum. We executed analyses to explicate heterogeneity in the cascade across key strata, as well as identify predictors of attrition across stages of the cascade. Methods Using linked individual-level data for the population of HIV-positive individuals in BC, we considered the 2011 calendar year, including individuals diagnosed at least 6 months prior, and excluding individuals that died or were lost to follow-up before January 1st, 2011. We defined five stages in the cascade framework: HIV ‘diagnosed’, ‘linked’ to care, ‘retained’ in care, ‘on HAART’ and virologically ‘suppressed’. We stratified the cascade by sex, age, risk category, and regional health authority. Finally, multiple logistic regression models were built to predict attrition across each stage of the cascade, adjusting for stratification variables. Results We identified 7621 HIV diagnosed individuals during the study period; 80% were male and 5% were <30, 17% 30–39, 37% 40–49 and 40% were ≥50 years. Of these, 32% were MSM, 28% IDU, 8% MSM/IDU, 12% heterosexual, and 20% other. Overall, 85% of individuals ‘on HAART’ were ‘suppressed’; however, this proportion ranged from 60%–93% in our various stratifications. Most individuals, in all subgroups, were lost between the stages: ‘linked’ to ‘retained’ and ‘on HAART’ to ‘suppressed’. Subgroups with the highest attrition between these stages included females and individuals <30 years (regardless of transmission risk group). IDUs experienced the greatest attrition of all subgroups. Logistic regression results found extensive statistically significant heterogeneity in attrition across the cascade between subgroups and regional health authorities. Conclusions We found that extensive heterogeneity in attrition existed across subgroups and regional health authorities along the HIV cascade of

  1. Acculturation, dietary practices and risk for childhood obesity in an ethnically heterogeneous population of Latino school children in the San Francisco bay area.

    PubMed

    Wojcicki, Janet M; Schwartz, Norah; Jiménez-Cruz, Arturo; Bacardi-Gascon, Montserrat; Heyman, Melvin B

    2012-08-01

    Previous studies have found increased acculturation to the US lifestyle increases risk for obesity in Latinos. However, methodologies differ, and results in children are inconsistent. Moreover, previous studies have not evaluated risk factors within the heterogeneous US population. We recruited 144 self-identified Latino school children and their mother or father in grades 4-6 in San Francisco parochial schools and South San Francisco public schools using an information letter distributed to all students. Children and parents had weights, heights, demographic information, dietary patterns and lifestyle variables collected in English or Spanish through an interview format. A high percentage of our children were overweight [≥85th percentile body mass index (BMI)] (62.5%) and obese (≥95th percentile BMI) (45.2%). Correspondingly parents also had a high percentage of overweight (BMI ≥ 25 & <30) (40.8%) and obesity (BMI ≥ 30) (45.3%). Mexico was the country of origin for 62.2% of parents, and 26.6% were from Central or South America. In multivariate logistic analysis, speaking Spanish at home was an independent risk factor for obesity [odds ratio (OR) 2.97, 95% confidence interval (CI) 1.28-6.86]. Eating breakfast daily (OR 0.34, 95% CI 0.15-0.78) and consumption of tortas (a Mexican fast food sandwich) (OR 0.45, 95% CI 0.21-1.00) were associated with decreased risk. In stratified analysis, significant differences in risk factors existed between Mexican origin versus Central/South American Latino children. The processes of acculturation likely impact eating and lifestyle practices differentially among Latino groups. Interventions should focus on ensuring that all children eat a nutritious breakfast and take into consideration ethnicity when working with Latino populations. PMID:22101726

  2. Investigating Population Heterogeneity and Interaction Effects of Covariates: The Case of a Large-Scale Assessment for Teacher Licensure in Saudi Arabia

    ERIC Educational Resources Information Center

    Dimitrov, Dimiter M.; Al-Saud, Faisal Abdullah Al-Mashari; Alsadaawi, Abdullah Saleh

    2015-01-01

    This article investigates the population heterogeneity of test data for the case of teacher licensure assessments in Saudi Arabia. The results from factor mixture modeling of the data (N = 15,962) on the construct of "promoting learning" revealed the presence of two latent classes of examinees based on their performance profiles across…

  3. A New Approach to Evaluation of University Teaching Considering Heterogeneity of Students' Preferences

    ERIC Educational Resources Information Center

    Kuzmanovic, Marija; Savic, Gordana; Popovic, Milena; Martic, Milan

    2013-01-01

    Students' evaluations of teaching are increasingly used by universities to evaluate teaching performance. However, these evaluations are controversial mainly due to the fact that students value various aspects of excellent teaching differently. Therefore, in this paper we propose a new approach to students' evaluations of university…

  4. Lack of oral HSV-2 in a college student population.

    PubMed

    Docherty, J J; Trimble, J J; Roman, S R; Faulkner, S C; Naugle, F P; Mundon, F K; Zimmerman, D H

    1985-07-01

    A population of individuals with a high incidence of genital herpes simplex virus type 1 (HSV-1), due most likely to oro-genital contact, was examined to determine the incidence of oral herpes simplex virus type 2 (HSV-2) infection. Herpes simplex virus was isolated from the oral cavity of 43 college students whose symptoms ranged from singular lesions of the lips with minimal discomfort to severe oral disease with systemic involvement resulting in lymphadenopathy, chills, sweat, myalgia, and fever. The virus isolated from each case was identified by serum neutralization and typed as HSV-1 or HSV-2 using (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) sensitivity, monoclonal antibody immunofluorescence, and restriction endonuclease EcoRI digestion of viral DNA. In every instance the isolate was HSV-1. Additional identification and typing of head and neck isolates as well as oral samples from non-university patients demonstrated that all were also HSV-1. Therefore, while HSV-1 appears to be readily transmitted to the genitalia in this group of individuals, the transmission of HSV-2 to the oral cavity may not be as common, even though clinical histories revealed that several of these patients were engaging in oro-genital contact. PMID:2993498

  5. Catalog of Exemplary Vocational Education Programs for California Community Colleges' Special Student Populations.

    ERIC Educational Resources Information Center

    Evaluation and Training Inst., Los Angeles, CA.

    This directory contains abstracts of 30 model programs for special population students at California community colleges. Programs are divided into four categories corresponding to the type of special population served. The seven programs for disadvantaged students are as follows: "Career Beginnings"; "Center for Computer Assisted Instruction and…

  6. The Effects of Homogeneous versus Heterogeneous Reading-Style Grouping on EFL Students' Non-Preferred Reading Style and Reading Comprehension

    ERIC Educational Resources Information Center

    El-Koumy, Abdel Salam Abdel Khalek

    2009-01-01

    The purpose of this study was to investigate the effects of homogeneous versus heterogeneous reading-style grouping on EFL students' non-preferred reading style and reading comprehension. The study used a pretest-posttest experimental design. The original subjects of the study (N=86) were Egyptian English major senior students during the 2005/2006…

  7. Beyond the Canon: Within-Plant and Population-Level Heterogeneity in Jasmonate Signaling Engaged by Plant-Insect Interactions.

    PubMed

    Li, Dapeng; Baldwin, Ian T; Gaquerel, Emmanuel

    2016-01-01

    Plants have evolved sophisticated communication and defense systems with which they interact with insects. Jasmonates are synthesized from the oxylipin pathway and act as pivotal cellular orchestrators of many of the metabolic and physiological processes that mediate these interactions. Many of these jasmonate-dependent responses are tissue-specific and translate from modulations of the canonical jasmonate signaling pathway. Here we provide a short overview of within-plant heterogeneities in jasmonate signaling and dependent responses in the context of plant-insect interactions as illuminated by examples from recent work with the ecological model, Nicotiana attenuata. We then discuss means of manipulating jasmonate signaling by creating tissue-specific jasmonate sinks, and the micrografting of different transgenic plants. The metabolic phenotyping of these manipulations provides an integrative understanding of the functional significance of deviations from the canonical model of this hormonal pathway. Additionally, natural variation in jasmonate biosynthesis and signaling both among and within species can explain polymorphisms in resistance to insects in nature. In this respect, insect-guided explorations of population-level variations in jasmonate metabolism have revealed more complexity than previously realized and we discuss how different "omic" techniques can be used to exploit the natural variation that occurs in this important signaling pathway. PMID:27135234

  8. Beyond the Canon: Within-Plant and Population-Level Heterogeneity in Jasmonate Signaling Engaged by Plant-Insect Interactions

    PubMed Central

    Li, Dapeng; Baldwin, Ian T.; Gaquerel, Emmanuel

    2016-01-01

    Plants have evolved sophisticated communication and defense systems with which they interact with insects. Jasmonates are synthesized from the oxylipin pathway and act as pivotal cellular orchestrators of many of the metabolic and physiological processes that mediate these interactions. Many of these jasmonate-dependent responses are tissue-specific and translate from modulations of the canonical jasmonate signaling pathway. Here we provide a short overview of within-plant heterogeneities in jasmonate signaling and dependent responses in the context of plant-insect interactions as illuminated by examples from recent work with the ecological model, Nicotiana attenuata. We then discuss means of manipulating jasmonate signaling by creating tissue-specific jasmonate sinks, and the micrografting of different transgenic plants. The metabolic phenotyping of these manipulations provides an integrative understanding of the functional significance of deviations from the canonical model of this hormonal pathway. Additionally, natural variation in jasmonate biosynthesis and signaling both among and within species can explain polymorphisms in resistance to insects in nature. In this respect, insect-guided explorations of population-level variations in jasmonate metabolism have revealed more complexity than previously realized and we discuss how different “omic” techniques can be used to exploit the natural variation that occurs in this important signaling pathway. PMID:27135234

  9. Bovine mammary dendritic cells: a heterogeneous population, distinct from macrophages and similar in phenotype to afferent lymph veiled cells.

    PubMed

    Maxymiv, Nicolas G; Bharathan, Mini; Mullarky, Isis K

    2012-01-01

    Dendritic cells (DC) are a heterogeneous population of professional antigen presenting cells and are potent stimulators of naïve T-cells. However, there is little previous research describing DC in bovine mammary tissue, primarily because of the difficulty distinguishing these cells from macrophages, which possess a similar phenotype. Using immunohistofluorescence and a combination of markers (MHC-II, CD205, CD11c), DC were localized in the bovine mammary gland and supramammary lymph node. In mammary tissue DC were found within the alveolar epithelium and within the intralobular connective tissue. In the lymph node DC were found on the periphery of B-cell areas, in the cortex, and among T-cells in the paracortex and medulla. DC in mammary parenchyma and supramammary lymph nodes were quantified and further characterized using flow cytometry. DC were CD11c(hi), CD14(lo) cells that expressed MHC-II and CD205. DC could be distinguished from macrophages based on their low CD14 expression. This research provides a better understanding of mammary gland immunology, while potentially aiding in the targeting of antigens to mucosal DC for vaccine development. PMID:22019401

  10. A Millifluidic Study of Cell-to-Cell Heterogeneity in Growth-Rate and Cell-Division Capability in Populations of Isogenic Cells of Chlamydomonas reinhardtii

    PubMed Central

    Damodaran, Shima P.; Eberhard, Stephan; Boitard, Laurent; Rodriguez, Jairo Garnica; Wang, Yuxing; Bremond, Nicolas; Baudry, Jean; Bibette, Jérôme; Wollman, Francis-André

    2015-01-01

    To address possible cell-to-cell heterogeneity in growth dynamics of isogenic cell populations of Chlamydomonas reinhardtii, we developed a millifluidic drop-based device that not only allows the analysis of populations grown from single cells over periods of a week, but is also able to sort and collect drops of interest, containing viable and healthy cells, which can be used for further experimentation. In this study, we used isogenic algal cells that were first synchronized in mixotrophic growth conditions. We show that these synchronized cells, when placed in droplets and kept in mixotrophic growth conditions, exhibit mostly homogeneous growth statistics, but with two distinct subpopulations: a major population with a short doubling-time (fast-growers) and a significant subpopulation of slowly dividing cells (slow-growers). These observations suggest that algal cells from an isogenic population may be present in either of two states, a state of restricted division and a state of active division. When isogenic cells were allowed to propagate for about 1000 generations on solid agar plates, they displayed an increased heterogeneity in their growth dynamics. Although we could still identify the original populations of slow- and fast-growers, drops inoculated with a single progenitor cell now displayed a wider diversity of doubling-times. Moreover, populations dividing with the same growth-rate often reached different cell numbers in stationary phase, suggesting that the progenitor cells differed in the number of cell divisions they could undertake. We discuss possible explanations for these cell-to-cell heterogeneities in growth dynamics, such as mutations, differential aging or stochastic variations in metabolites and macromolecules yielding molecular switches, in the light of single-cell heterogeneities that have been reported among isogenic populations of other eu- and prokaryotes. PMID:25760649

  11. A millifluidic study of cell-to-cell heterogeneity in growth-rate and cell-division capability in populations of isogenic cells of Chlamydomonas reinhardtii.

    PubMed

    Damodaran, Shima P; Eberhard, Stephan; Boitard, Laurent; Rodriguez, Jairo Garnica; Wang, Yuxing; Bremond, Nicolas; Baudry, Jean; Bibette, Jérôme; Wollman, Francis-André

    2015-01-01

    To address possible cell-to-cell heterogeneity in growth dynamics of isogenic cell populations of Chlamydomonas reinhardtii, we developed a millifluidic drop-based device that not only allows the analysis of populations grown from single cells over periods of a week, but is also able to sort and collect drops of interest, containing viable and healthy cells, which can be used for further experimentation. In this study, we used isogenic algal cells that were first synchronized in mixotrophic growth conditions. We show that these synchronized cells, when placed in droplets and kept in mixotrophic growth conditions, exhibit mostly homogeneous growth statistics, but with two distinct subpopulations: a major population with a short doubling-time (fast-growers) and a significant subpopulation of slowly dividing cells (slow-growers). These observations suggest that algal cells from an isogenic population may be present in either of two states, a state of restricted division and a state of active division. When isogenic cells were allowed to propagate for about 1000 generations on solid agar plates, they displayed an increased heterogeneity in their growth dynamics. Although we could still identify the original populations of slow- and fast-growers, drops inoculated with a single progenitor cell now displayed a wider diversity of doubling-times. Moreover, populations dividing with the same growth-rate often reached different cell numbers in stationary phase, suggesting that the progenitor cells differed in the number of cell divisions they could undertake. We discuss possible explanations for these cell-to-cell heterogeneities in growth dynamics, such as mutations, differential aging or stochastic variations in metabolites and macromolecules yielding molecular switches, in the light of single-cell heterogeneities that have been reported among isogenic populations of other eu- and prokaryotes. PMID:25760649

  12. Population heterogeneity and dynamics in starter culture and lag phase adaptation of the spoilage yeast Zygosaccharomyces bailii to weak acid preservatives

    PubMed Central

    Stratford, Malcolm; Steels, Hazel; Nebe-von-Caron, Gerhard; Avery, Simon V.; Novodvorska, Michaela; Archer, David B.

    2014-01-01

    The food spoilage yeast Zygosaccharomyces bailii shows great resistance to weak-acid preservatives, including sorbic acid (2, 4-hexadienoic acid). That extreme resistance was shown to be due to population heterogeneity, with a small sub-population of cells resistant to a variety of weak acids, probably caused by a lower internal pH reducing the uptake of all weak acids. In the present paper, it was found that resistant cells were extremely rare in exponential cultures, but increased by up to 8000-fold in stationary phase. Inoculation of media containing sorbic acid with a population of Z. bailii cells gave rise to what appeared to be a prolonged lag phase, suggesting adaptation to the conditions before the cells entered the period of exponential growth. However, the apparent lag phase caused by sorbic acid was largely due to the time required for the resistant sub-population to grow to detectable levels. The slow growth rate of the sub-population was identical to that of the final total population. The non-resistant bulk population remained viable for 3 days but had lost viability by 6 days and, during that time, there was no indication of any development of resistance in the bulk population. The sub-population growing in sorbic acid showed very high population diversity in colony size and internal pH. After removal of sorbic acid, the population rapidly reverted back to the normal, largely non-resistant, population distribution. The data presented suggest that a reevaluation of the lag phase in microbial batch culture is required, at least for the resistance of Z. bailii to sorbic acid. Furthermore, the significance of phenotypic diversity and heterogeneity in microbial populations is discussed more broadly with potential relevance to bacterial “persisters”, natural selection and evolution. PMID:24813627

  13. The Impact of Multi-Dimensional Behavioral Interventions in Student Conduct Processes: Achieving Increased Learning Outcomes in Adult Student Populations

    ERIC Educational Resources Information Center

    Braddix, D'Andre Cortez

    2012-01-01

    As adult students constitute nearly half of all undergraduates in the United States, college practitioners need to identify effective disciplinary strategies for this population when violations of institutional rules and regulations occur. The purpose of this quasi-experimental, action research study was to modify the student conduct process for…

  14. Class Size Effects on Student Achievement: Heterogeneity across Abilities and Fields

    ERIC Educational Resources Information Center

    De Paola, Maria; Ponzo, Michela; Scoppa, Vincenzo

    2013-01-01

    In this paper, we analyze class size effects on college students exploiting data from a project offering special remedial courses in mathematics and language skills to freshmen enrolled at an Italian medium-sized public university. To estimate the effects of class size, we exploit the fact that students and teachers are virtually randomly assigned…

  15. Grants in Italian University: A Look at the Heterogeneity of Their Impact on Students' Performances

    ERIC Educational Resources Information Center

    Agasisti, Tommaso; Murtinu, Samuele

    2016-01-01

    In this paper, we estimate the effect of receiving financial aid for a cohort of students who enrolled at Politecnico di Milano (Italy) in the year 2007/2008, through a propensity score matching approach. Using administrative data about these students for four years, the impact of the financial aid on several dimensions of academic performance was…

  16. Nurturing Gifted Students' Metacognitive Awareness: Effects of Training in Homogeneous and Heterogeneous Classes.

    ERIC Educational Resources Information Center

    Sheppard, Shelby; Kanevsky, Lannie S.

    1999-01-01

    A study of six gifted elementary students found that students in the homogeneous gifted class showed a greater increase in the number of control functions performed by the mind-machines they proposed, offered descriptions of their machines which were longer, more sophisticated, and more creative, and leap-frogged off of each others' ideas.…

  17. Heterogeneity of Borrelia burgdorferi Sensu Stricto Population and Its Involvement in Borrelia Pathogenicity: Study on Murine Model with Specific Emphasis on the Skin Interface

    PubMed Central

    Kern, Aurélie; Schnell, Gilles; Bernard, Quentin; Bœuf, Amandine; Jaulhac, Benoît; Collin, Elody; Barthel, Cathy

    2015-01-01

    Lyme disease is a multisystemic disorder caused by B. burgdorferi sl. The molecular basis for specific organ involvement is poorly understood. The skin plays a central role in the development of Lyme disease as the entry site of B. burgdorferi in which specific clones are selected before dissemination. We compared the skin inflammatory response (antimicrobial peptides, cytokines and chemokines) elicited by spirochete populations recovered from patients presenting different clinical manifestations. Remarkably, these spirochete populations induced different inflammatory profiles in the skin of C3H/HeN mice. As spirochete population transmitted into the host skin is heterogeneous, we isolated one bacterial clone from a population recovered from a patient with neuroborreliosis and compared its virulence to the parental population. This clone elicited a strong cutaneous inflammatory response characterized by MCP-1, IL-6 and antimicrobial peptides induction. Mass spectrometry of this clone revealed 110 overexpressed proteins when compared with the parental population. We further focused on the expression of nine bacterial surface proteins. bb0347 coding for a protein that interacts with host fibronectin, allowing bacterial adhesion to vascular endothelium and extracellular matrix, was found to be induced in host skin with another gene bb0213 coding for a hypothetical protein. These findings demonstrate the heterogeneity of the B. burgdorferi ss population and the complexity of the interaction involved early in the skin. PMID:26197047

  18. Stress indicators based on airborne thermal imagery for field phenotyping a heterogeneous tree population for response to water constraints

    PubMed Central

    Virlet, Nicolas; Lebourgeois, Valentine; Martinez, Sébastien; Costes, Evelyne; Labbé, Sylvain; Regnard, Jean-Luc

    2014-01-01

    As field phenotyping of plant response to water constraints constitutes a bottleneck for breeding programmes, airborne thermal imagery can contribute to assessing the water status of a wide range of individuals simultaneously. However, the presence of mixed soil–plant pixels in heterogeneous plant cover complicates the interpretation of canopy temperature. Moran’s Water Deficit Index (WDI = 1–ETact/ETmax), which was designed to overcome this difficulty, was compared with surface minus air temperature (T s–T a) as a water stress indicator. As parameterization of the theoretical equations for WDI computation is difficult, particularly when applied to genotypes with large architectural variability, a simplified procedure based on quantile regression was proposed to delineate the Vegetation Index–Temperature (VIT) scatterplot. The sensitivity of WDI to variations in wet and dry references was assessed by applying more or less stringent quantile levels. The different stress indicators tested on a series of airborne multispectral images (RGB, near-infrared, and thermal infrared) of a population of 122 apple hybrids, under two irrigation regimes, significantly discriminated the tree water statuses. For each acquisition date, the statistical method efficiently delineated the VIT scatterplot, while the limits obtained using the theoretical approach overlapped it, leading to inconsistent WDI values. Once water constraint was established, the different stress indicators were linearly correlated to the stem water potential among a tree subset. T s–T a showed a strong sensitivity to evaporative demand, which limited its relevancy for temporal comparisons. Finally, the statistical approach of WDI appeared the most suitable for high-throughput phenotyping. PMID:25080086

  19. Disease and disaster: Optimal deployment of epidemic control facilities in a spatially heterogeneous population with changing behaviour.

    PubMed

    Gaythorpe, Katy; Adams, Ben

    2016-05-21

    Epidemics of water-borne infections often follow natural disasters and extreme weather events that disrupt water management processes. The impact of such epidemics may be reduced by deployment of transmission control facilities such as clinics or decontamination plants. Here we use a relatively simple mathematical model to examine how demographic and environmental heterogeneities, population behaviour, and behavioural change in response to the provision of facilities, combine to determine the optimal configurations of limited numbers of facilities to reduce epidemic size, and endemic prevalence. We show that, if the presence of control facilities does not affect behaviour, a good general rule for responsive deployment to minimise epidemic size is to place them in exactly the locations where they will directly benefit the most people. However, if infected people change their behaviour to seek out treatment then the deployment of facilities offering treatment can lead to complex effects that are difficult to foresee. So careful mathematical analysis is the only way to get a handle on the optimal deployment. Behavioural changes in response to control facilities can also lead to critical facility numbers at which there is a radical change in the optimal configuration. So sequential improvement of a control strategy by adding facilities to an existing optimal configuration does not always produce another optimal configuration. We also show that the pre-emptive deployment of control facilities has conflicting effects. The configurations that minimise endemic prevalence are very different to those that minimise epidemic size. So cost-benefit analysis of strategies to manage endemic prevalence must factor in the frequency of extreme weather events and natural disasters. PMID:26992574

  20. Stress indicators based on airborne thermal imagery for field phenotyping a heterogeneous tree population for response to water constraints.

    PubMed

    Virlet, Nicolas; Lebourgeois, Valentine; Martinez, Sébastien; Costes, Evelyne; Labbé, Sylvain; Regnard, Jean-Luc

    2014-10-01

    As field phenotyping of plant response to water constraints constitutes a bottleneck for breeding programmes, airborne thermal imagery can contribute to assessing the water status of a wide range of individuals simultaneously. However, the presence of mixed soil-plant pixels in heterogeneous plant cover complicates the interpretation of canopy temperature. Moran's Water Deficit Index (WDI = 1-ETact/ETmax), which was designed to overcome this difficulty, was compared with surface minus air temperature (T s-T a) as a water stress indicator. As parameterization of the theoretical equations for WDI computation is difficult, particularly when applied to genotypes with large architectural variability, a simplified procedure based on quantile regression was proposed to delineate the Vegetation Index-Temperature (VIT) scatterplot. The sensitivity of WDI to variations in wet and dry references was assessed by applying more or less stringent quantile levels. The different stress indicators tested on a series of airborne multispectral images (RGB, near-infrared, and thermal infrared) of a population of 122 apple hybrids, under two irrigation regimes, significantly discriminated the tree water statuses. For each acquisition date, the statistical method efficiently delineated the VIT scatterplot, while the limits obtained using the theoretical approach overlapped it, leading to inconsistent WDI values. Once water constraint was established, the different stress indicators were linearly correlated to the stem water potential among a tree subset. T s-T a showed a strong sensitivity to evaporative demand, which limited its relevancy for temporal comparisons. Finally, the statistical approach of WDI appeared the most suitable for high-throughput phenotyping. PMID:25080086

  1. Guidelines for Death Notification in College Student Populations

    ERIC Educational Resources Information Center

    Hamilton, Lou Ann

    2008-01-01

    College is a time for intellectual growth and also an important time for psychological and emotional maturation and the development of coping skills. The death loss of a family member or friend is a relatively common experience for college students. How students and family members are notified of a death can have a long-standing impact on their…

  2. The relative influence of climate, environmental heterogeneity, and human population on the distribution of vertebrate species richness in south-eastern Spain

    NASA Astrophysics Data System (ADS)

    Moreno-Rueda, Gregorio; Pizarro, Manuel

    2007-07-01

    In view of the many factors affect species richness, this study examines the relative influence of environmental heterogeneity, climate, human disturbance and spatial structure with respect to the species-richness distribution of terrestrial vertebrates in an area of south-eastern Spain with a Mediterranean climate. We show that environmental heterogeneity was the primary factor determining species richness (20.3% of variance), with the effect of temperature and precipitation being lower (11.6%). Climate had greater importance in determining the species richness of ectotherms (amphibians and reptiles) than of endotherms (mammals and birds). Species richness had less spatial autocorrelation in mammals and birds than in ectotherms. Also, a positive correlation was found between species richness and human population density, especially in reptiles and mammals. Orders and families more sensitive to human presence, such as snakes, raptors, ungulates, and carnivores, showed no relationship (or a negative one) with the human population. This study highlights the importance of environmental heterogeneity (topographic heterogeneity and habitat diversity) for vertebrate conservation in zones with a Mediterranean climate.

  3. The heterogeneous HLA genetic composition of the Brazilian population and its relevance to the optimization of hematopoietic stem cell donor recruitment.

    PubMed

    Fabreti-Oliveira, R A; Nascimento, E; Fonseca, C G; Santos, M A

    2014-08-01

    The aim of this study was to investigate the human leukocyte antigen (HLA) molecular variation across the Brazilian population in order to determine possible regional differences, which would be highly relevant to optimizing donor recruitment strategies in hematopoietic stem cell transplantation (HSCT) and understanding the population genetic background of this heterogeneous country. HLA data of 551 HSCT donors from five Brazilian regions were characterized by high-resolution DNA alleles at the HLA-A, -B, -C, -DRB1 and -DQB1 loci and compared with other populations in Brazil and worldwide populations. Allele and haplotype frequencies were estimated. The analysis was performed to assess Hardy-Weinberg equilibrium (HWE) and linkage disequilibrium (LD) among different loci in each recruitment center. Genetic variation was explored through genetic distance analyzed by using a new algorithm based on linear algebra, taking into account geographic regions of Brazil. The results indicated a heterogeneous genetic composition of the Brazilian population, such that HLA allele and haplotype frequencies exhibit different distributions among Brazilian regions, which has important implications for donor matching. In addition, a pronounced differentiation was observed by the absence of clustering of the regional populations in the reduced-dimension space. These data may be useful for increasing donor recruitment with more genetic representativeness in the Brazilian Volunteer Bone Marrow Donors Registry (REDOME). PMID:24724906

  4. School Enrollment--Social and Economic Characteristics of Students: October 1985 and 1984. Current Population Reports: Population Characteristics.

    ERIC Educational Resources Information Center

    Bruno, Rosalind R.

    1988-01-01

    Using data from the October supplements to the Current Population Survey (CPS), collected in 1984 and 1985, this report presents statistical information on students in the United States attending nursery school through college by age, race, Spanish origin, sex, marital status, household relationship, residence, and family income. The data are…

  5. Changes in Dental Students' Attitudes About Treating Underserved Populations: A Longitudinal Study.

    PubMed

    Major, Nicole; McQuistan, Michelle R; Qian, Fang

    2016-05-01

    The aim of this study was to assess changes in a group of dental students' feelings about, willingness to treat, and perceived responsibility in treating underserved populations as they progressed through their predoctoral education. A questionnaire was developed to assess the first- through fourth-year (D1-D4) students' attitudes about treating 13 underserved populations after graduation. Surveys were distributed from 2008 to 2014, resulting in longitudinal data from three graduating classes (D1 year: N=240; eligible D4 participants: N=221). A total of 132 students from the three classes (Class of 2012 N=41; 2013 N=46; 2014 N=45; adjusted response rate 60%) completed all surveys (D1-D4). The results showed that changes in students' feelings about treating and willingness to treat underserved populations were population-specific rather than universal. Compared to the D1 year, the students in later years anticipated feeling more negatively towards treating low-income, frail elderly, homebound, homeless, other ethnic groups, and non-English-speaking patients, while their feelings were more positive towards treating known drug users and HIV/AIDS populations. Across the four years, students' willingness to treat low-income, frail elderly, homebound, and non-English-speaking populations after graduation became more negative, while their willingness to treat medically complex populations, known drug users, and HIV/AIDS populations became more positive. The students also became less likely to strongly agree that it is their responsibility as dentists to treat underserved populations as they progressed through school. These respondents reported that clinical and faculty interactions had impacted their likelihood to treat underserved populations. These findings may point to specific types of interventions and faculty mentoring to bring about change. PMID:27139202

  6. With Educational Benefits for All: Campus Inclusion through Learning Communities Designed for Underserved Student Populations

    ERIC Educational Resources Information Center

    Fink, John E.; Hummel, Mary L.

    2015-01-01

    This chapter explores the practices of learning communities designed for specific, underserved student populations, highlighting on-campus examples and culminating with a synthesized list of core practices from these "inclusive" learning communities.

  7. The Henry street consortium population-based competencies for educating public health nursing students.

    PubMed

    Schaffer, Marjorie A; Cross, Sharon; Keller, Linda O; Nelson, Pamela; Schoon, Patricia M; Henton, Pat

    2011-01-01

    The Henry Street Consortium, a collaboration of nurse educators from universities and colleges and public health nurses (PHNs) from government, school, and community agencies, developed 11 population-based competencies for educating nursing students and the novice PHN. Although many organizations have developed competency lists for experts, the Consortium developed a set of competencies that clearly define expectations for the beginning PHN. The competencies are utilized by both education and practice. They guide nurse educators and PHNs in the creation of learning experiences that develop population-based knowledge and skills for baccalaureate nursing students. Public health nursing leaders use the competencies to frame their expectations and orientations for nurses who are new to public health nursing. This paper explains the meaning of each of the 11 population-based competencies and provides examples of student projects that demonstrate competency development. Strategies are suggested for nurse educators and PHNs to promote effective population-based student projects in public health agencies. PMID:21198818

  8. Peer bullying in a pre-registration student nursing population.

    PubMed

    Cooper, Brenda; Curzio, Joan

    2012-11-01

    Peer bullying is a major problem in schools and workplaces including the National Health Service. Although there are a few published studies exploring the incidence of peer bullying among university students, none is specific to pre-registration nursing students. Nursing programmes are delivered across two campuses of the university however students registered at individual campuses do not mix which makes the experiences of each campus individual. The aim of this study was to explore the incidence and manifestation of peer bullying amongst pre-registration nursing students in the university setting. The study describes the reported incidence of the three types of peer bullying behaviour: physical, verbal and non-verbal bullying. Participants in their final year of adult nurse education were asked to explore their perceptions of peer bullying, the frequency of witnessed or experienced behaviour and the location of where this behaviour occurred on the university campuses via a quantitative questionnaire. In total 190 students were surveyed with 156 (82%) responding. Participants reported peer bullying is experienced by student nurses on university premises and that academic members of staff are sometimes present when this behaviour is demonstrated. Reported levels of bullying decreased during their 2nd and 3rd years of the course compared to the foundation year. This decrease may have been in response to the university's strong anti-bullying stance. PMID:22093882

  9. The Effect of Accelerated Mathematics Instruction on Heterogeneous Groups of Sixth Grade Students

    ERIC Educational Resources Information Center

    Nance, Wendy J.

    2013-01-01

    The United States currently lags behind globally in the areas of math and science. In order to compete and meet the skills necessary for the future workforce, it has become necessary to seek out instructional strategies that will increase student achievement in those academic areas. With the wide variety of diversity occurring in public schools…

  10. Sample Heterogeneity and the Measurement Structure of the Multidimensional Students' Life Satisfaction Scale

    ERIC Educational Resources Information Center

    Sawatzky, Richard; Ratner, Pamela A.; Johnson, Joy L.; Kopec, Jacek A.; Zumbo, Bruno D.

    2009-01-01

    Several measurement assumptions were examined with the goal of assessing the validity of the Multidimensional Students' Life Satisfaction Scale (MSLSS), a measure of adolescents' satisfaction with their family, friends, living environment, school, self, and general quality of life. The data were obtained via a cross-sectional survey of 8,225…

  11. Variables Associated With Reading and Math Achievement among a Heterogeneous Group of Students.

    ERIC Educational Resources Information Center

    Oakland, Thomas; Stern, William

    1989-01-01

    Delineated characteristics of over- and under-achievers within a sample of 372 randomly selected public school students aged 6 through 17 years from 3 racial-ethnic groups and 2 levels of socioeconomic status. Found discrepant achievement not to be unique to particular race, intelligence, gender, age, family size, or degree of family intactness.…

  12. Molecular heterogeneity of G6PD deficiency in an Amazonian population and description of four new variants.

    PubMed

    Hamel, Arno Rolf; Cabral, Isabel Rosa; Sales, Tereza Sueko Ide; Costa, Fernando Ferreira; Olalla Saad, Sara Teresinha

    2002-01-01

    To characterize the molecular variation in the glucose-6-phosphate dehydrogenase gene (G6PD), 196 asymptomatic and unrelated male G6PD-deficient blood donors from Belém, an Amazonian metropolis (Brazil), were analyzed. This deficiency was detected by horizontal agarose gel electrophoresis and quantitative spectrophotometric assay for enzyme activity. The mutations were searched by PCR/RFLP, SSCP, and direct DNA sequencing. The most frequent G6PD variant was the widespread and common G6PD A- (202G --> A, 376A --> G) observed in 161 subjects (82.1%). Besides this, we found another form of G6PD A- (968T --> C, 376A --> G) in 14 (7.1%) individuals, G6PD Seattle (844G --> C) in 4.6%, G6PD Santamaria (542A --> T, 376A --> G) in 2.5%, and G6PD Tokyo (1246G --> A) in one blood donor. Four novel variants were also identified: G6PD Belém (409C --> T; Pro137His), G6PD Ananindeua (376A --> G, 871G --> A; Asn126Asp, Val291Met), G6PD Crispim with four point mutations (375G --> T, 379G --> T, 383T --> C, and 384C --> T) leading to three amino acid substitutions (Met125Ile, Ala127Ser, and Leu128Pro), and G6PD Amazonia (185C --> A; Pro62His). The reported frequencies do not reflect the real values for blood donors from Belém, since an excess of individuals with "non A-" phenotype was included in this study to enhance the probability to find rare variants. Haplotype analyses were carried out for the less common G6PD variants identified in our study using PCR/RFLP for five polymorphic sites (FokI, PvuII, PstI, BclI, NlaIII). G6PD Crispim and G6PD Amazonia variants presented the most common haplotype found in G6PD B (- - + - -). G6PD Belém presented two haplotypes (- - + + +, - + + + +) and G6PD Ananindeua was found with the + - + - + haplotype. The reported heterogeneity probably is due to the great miscegenation, characteristic of the population of the Amazonian region, besides the apparently common occurrence of recurrent mutations in the G6PD gene. PMID:12367584

  13. Prevalence of oral mucosal lesions among Pre-University students of Kodava population in Coorg District

    PubMed Central

    Sandeepa, N C; Jaishankar, H P; Sharath, Chandra B; Abhinetra, M S; Darshan, D D; Deepika, Nappalli

    2013-01-01

    Background: To know the prevalence of oral mucosal lesions among Pre-University students of Kodava population in Coorg District. This survey also aims to find out tobacco or other habits among students and related changes in the oral environment. Materials & Methods: 900 PU students of Kodava population were included. 300 students from each taluk were randomly selected, after the consent. Questions were asked to reveal the systemic diseases, abnormal oral habits, use of tobacco &alcohol. Each student was examined for oral mucosal lesions and recording was based on WHO oral health assessment form. Results: Oral mucosal lesions were similar to studies done in other population but with a slightly higher frequency of few lesions. Incidence of substance use was noted, but with no signs of significant changes in the oral mucosa. Conclusion: Prevalence of oral mucosal lesions varies among each population indicating the need for study in each population to format health policy. Substance use was noted among 16-17 yr age group indicates the need for early preventive measures among adolescents to avoid future serious health problems. How to cite this article: Sandeepa N C, Jaishankar H P, Sharath C B, Abhinetra M S, Darshan D D, Nappalli D. Prevalence of oral mucosal lesions among Pre-University students of Kodava population in Coorg District. J Int Oral Health 2013; 5(3):35-41. PMID:24155600

  14. Are New Generations of Female College-Student Populations Meeting Calcium Requirements: Comparison of American and Croatian Female Students

    PubMed Central

    Douglas, Crystal C.; Rumbak, Ivana; Barić, Irena Colić; Kovačina, Marinela; Piasek, Martina; Ilich, Jasminka Z.

    2010-01-01

    We compared calcium (Ca) sources and intake, as well as multivitamin/mineral supplement use between female students with nutrition/health background and those from general-student-populations. 314 participants 18–37 y, including 57 African-Americans and 54 Caucasian-Americans recruited from Nutrition and/or other Health Sciences departments (NHS), and 100 African-American and 103 Croatian women representing general-student-population (GSP), completed food frequency questionnaire assessing their usual Ca intake and supplement use. NHS populations met recommendations and consumed significantly more Ca, particularly from dairy sources, and were more likely to take supplements than GSP groups, suggesting that health education may influence Ca intake. PMID:22254044

  15. Pregnant and Parenting Students on Campus: Policy and Program Implications for a Growing Population

    ERIC Educational Resources Information Center

    Brown, Virginia; Nichols, Tracy R.

    2013-01-01

    The number of pregnant and parenting students in higher education is increasing. Research suggests this population experiences added pressure and stress while pursuing their education. Few resources exist for these students and the universities who provide services do not adequately promulgate them to the campus community. The research presented…

  16. An Analysis of Supports for Persistence for the Military Student Population

    ERIC Educational Resources Information Center

    Mentzer, Bruce; Black, Ellen Lowrie; Spohn, R. Terry

    2015-01-01

    This study sought to describe the correlation of academic, financial, and social supports to the persistence of a military student population: veterans, active duty and their families. The study also contrasted these relationships with those of nonmilitary students and looked at the results of both groups together to determine how supports…

  17. Connections: Linking Population and the Environment. Student Resource Book and Teacher's Guide.

    ERIC Educational Resources Information Center

    Crews, Kimberly A., Ed.; Cancellier, Patricia, Ed.

    A teacher's guide and student resource book developed by geography, social studies and economics teachers comprise this teaching kit. The kit was developed to help seventh through twelfth grade students understand the links between population and the environment in the context of sustainable development. The goal of the project is to develop…

  18. Geography, the Integrating Discipline: Explaining China's Population-Driven Geopolitics to Students

    ERIC Educational Resources Information Center

    Bouchat, Clarence J.

    2008-01-01

    This article demonstrates geography's role as an integrative discipline and its utility in connecting students to the world around them. A case study links China's demography and its geopolitics to the lives of U.S. students. The relationship of China's population pressures to its resulting economic growth, need for economic resources, and…

  19. Minority Student Response to the Anthropology of Asian Black Populations. Revised.

    ERIC Educational Resources Information Center

    Warren, Charles P.

    Since 1970, the University of Chicago has offered three undergraduate anthropology courses on Philippine Negrito and Malay and Thai aboriginal black populations. Between 1975 and 1981, 72 students, including American blacks, Filipinos, and other Asians, attended the courses. The instructor's observations of students' responses to the courses…

  20. Genetic Geostatistical Framework for Spatial Analysis of Fine-Scale Genetic Heterogeneity in Modern Populations: Results from the KORA Study.

    PubMed

    Diaz-Lacava, A N; Walier, M; Holler, D; Steffens, M; Gieger, C; Furlanello, C; Lamina, C; Wichmann, H E; Becker, T

    2015-01-01

    Aiming to investigate fine-scale patterns of genetic heterogeneity in modern humans from a geographic perspective, a genetic geostatistical approach framed within a geographic information system is presented. A sample collected for prospective studies in a small area of southern Germany was analyzed. None indication of genetic heterogeneity was detected in previous analysis. Socio-demographic and genotypic data of German citizens were analyzed (212 SNPs; n = 728). Genetic heterogeneity was evaluated with observed heterozygosity (H O ). Best-fitting spatial autoregressive models were identified, using socio-demographic variables as covariates. Spatial analysis included surface interpolation and geostatistics of observed and predicted patterns. Prediction accuracy was quantified. Spatial autocorrelation was detected for both socio-demographic and genetic variables. Augsburg City and eastern suburban areas showed higher H O values. The selected model gave best predictions in suburban areas. Fine-scale patterns of genetic heterogeneity were observed. In accordance to literature, more urbanized areas showed higher levels of admixture. This approach showed efficacy for detecting and analyzing subtle patterns of genetic heterogeneity within small areas. It is scalable in number of loci, even up to whole-genome analysis. It may be suggested that this approach may be applicable to investigate the underlying genetic history that is, at least partially, embedded in geographic data. PMID:26258132

  1. Genetic Geostatistical Framework for Spatial Analysis of Fine-Scale Genetic Heterogeneity in Modern Populations: Results from the KORA Study

    PubMed Central

    Diaz-Lacava, A. N.; Walier, M.; Holler, D.; Steffens, M.; Gieger, C.; Furlanello, C.; Lamina, C.; Wichmann, H. E.; Becker, T.

    2015-01-01

    Aiming to investigate fine-scale patterns of genetic heterogeneity in modern humans from a geographic perspective, a genetic geostatistical approach framed within a geographic information system is presented. A sample collected for prospective studies in a small area of southern Germany was analyzed. None indication of genetic heterogeneity was detected in previous analysis. Socio-demographic and genotypic data of German citizens were analyzed (212 SNPs; n = 728). Genetic heterogeneity was evaluated with observed heterozygosity (HO). Best-fitting spatial autoregressive models were identified, using socio-demographic variables as covariates. Spatial analysis included surface interpolation and geostatistics of observed and predicted patterns. Prediction accuracy was quantified. Spatial autocorrelation was detected for both socio-demographic and genetic variables. Augsburg City and eastern suburban areas showed higher HO values. The selected model gave best predictions in suburban areas. Fine-scale patterns of genetic heterogeneity were observed. In accordance to literature, more urbanized areas showed higher levels of admixture. This approach showed efficacy for detecting and analyzing subtle patterns of genetic heterogeneity within small areas. It is scalable in number of loci, even up to whole-genome analysis. It may be suggested that this approach may be applicable to investigate the underlying genetic history that is, at least partially, embedded in geographic data. PMID:26258132

  2. A student-oriented study tool for heterogeneous HyperCard courseware.

    PubMed

    Rathe, R; Garren, T

    1991-01-01

    Several computer-assisted instruction initiatives at our institution rely on a shared laserdisc for image storage and HyperCard for interactive programming. This paper furnishes a brief overview of problems encountered with multimedia projects and how we are attempting to overcome them using a generic, student-oriented study tool. The tool provides bookmarks, annotations, quotations, and other utilities across our entire HyperCard courseware collection. PMID:1807701

  3. Changes in Student Populations and Average Test Scores of Dutch Primary Schools

    ERIC Educational Resources Information Center

    Luyten, Hans; de Wolf, Inge

    2011-01-01

    This article focuses on the relation between student population characteristics and average test scores per school in the final grade of primary education from a dynamic perspective. Aggregated data of over 5,000 Dutch primary schools covering a 6-year period were used to study the relation between changes in school populations and shifts in mean…

  4. Assignment of a gene for autosomal recessive retinitis pigmentosa (RP12) to chromosome 1q31-q32.1 in an inbred and genetically heterogeneous disease population

    SciTech Connect

    Van Soest, S.; Ingeborgh Van Den Born, L.; Bergen, A.A.B.

    1994-08-01

    Linkage analysis was carried out in a large family segregating for autosomal recessive retinitis pigmentosa (arRP), originating from a genetically isolated population in The Netherlands. Within the family, clinical heterogeneity was observed, with a major section of the family segregating arRP with characteristic para-arteriolar preservation of the retinal pigment epithelium (PPRPE). In the remainder of the arRP patients no PPRPE was found. Initially, all branches of the family were analyzed jointly, and linkage was found between the marker F13B, located at 1q31-q32.1, and RP12 ({Zeta}{sub max} = 4.99 at 8% recombination). Analysis of linkage heterogeneity between five branches of the family yielded significant evidence for nonallelic genetic heterogeneity within this family, coinciding with the observed clinical differences. Multipoint analysis, carried out in the branches that showed linkage, favored the locus order 1cen-D1S158-(F13B, RP12)-D1S53-1qter ({Zeta}{sub max} = 9.17). The finding of a single founder allele associated with the disease phenotype supports this localization. This study reveals that even in a large family, apparently segregating for a single disease entity, genetic heterogeneity can be detected and resolved successfully. 35 refs., 5 figs.

  5. ["Daily problems" as stressing factors in a student population].

    PubMed

    Farnè, M; Sebellico, A; Causarano, C

    1990-04-01

    An enquiry has been conducted to identify the most common hassles among University students (N = 169); from the 62 most frequently reported, a 62-item Daily Hassle Index has been developed. By asking the subjects to indicate how often each problem distressed them, the ten most commonly irritating hassles were isolated. PMID:2390229

  6. Treatment of Bipolar Disorder in the University Student Population

    ERIC Educational Resources Information Center

    Federman, Russ

    2011-01-01

    University counseling centers are faced with the challenge of effectively treating bipolar students while also utilizing brief treatment frameworks and managing high patient volumes. Potential destabilization, particularly within the elevated mood phase, poses significant behavioral management issues for university clinicians and administrators,…

  7. Changing Patterns of Cervical Disease in a Student Population.

    ERIC Educational Resources Information Center

    Rosenthal, Dorothy L.; And Others

    1982-01-01

    The Cytology Service at the University of California at Los Angeles (UCLA) Center for Health Sciences has examined about 4000 pap smears (each year) from the UCLA Student Health Service between 1973-1978. An apparently significant increase in abnormal pap smears in young college-age women is reported. (Authors/CJ)

  8. The Effects of an Inquiry-Internet Research Project on Motivation, Self-Efficacy, and Academic Autonomy in Heterogenously Grouped High School Latin I Students

    ERIC Educational Resources Information Center

    Wagman, Janet Campbell

    2005-01-01

    The purpose of this study was to analyze and induce change to lessen the achievement gap in heterogeneously grouped high school Latin classes where some students may be at academic risk, due to insufficient knowledge, inability to connect with the subject, and poor performances. The researcher engaged in action research, a branch of qualitative…

  9. Short- and Long-Term Outcomes of Student Field Research Experiences in Special Populations.

    PubMed

    Soliman, Amr S; Chamberlain, Robert M

    2016-06-01

    Global health education and training of biomedical students in international and minority health research is expending through U.S. academic institutions. This study addresses the short- and long-term outcomes of an NCI-funded R25 short-term summer field research training program. This program is designed for MPH and Ph.D. students in cancer epidemiology and related disciplines, in international and minority settings (special populations) in a recent 7-year period. Positive short-term outcome of 73 students was measured as publishing a manuscript from the field research data and having a job in special populations. Positive long-term outcome was measured as having a post-doc position, being in a doctoral program, and/or employment in special populations at least 3 years from finishing the program. Significant factors associated with both short- and long-term success included resourcefulness of the student and compatibility of personalities and interests between the student and the on-campus and off-campus mentors. Short-term-success of students who conducted international filed research was associated with visits of the on-campus mentor to the field site. Short-term success was also associated with extent of mentorship in the field site and with long-term success. Future studies should investigate how field research sites could enhance careers of students, appropriateness of the sites for specific training competencies, and how to maximize the learning experience of students in international and minority research sites. PMID:25773133

  10. Social Media and Population Health Virtual Exchange for Senior Nursing Students: An International Collaboration.

    PubMed

    Procter, Paula M; Brixey, Juliana J; Honey, Michelle L L; Todhunter, Fern

    2016-01-01

    The authors have all engaged in using social media with students as a means for collaboration across national and international boundaries for various educational purposes. Following the explosion of big data in health the authors are now moving this concept forward within undergraduate and postgraduate nursing curricula for the development of population health virtual exchanges. Nursing has a global presence and yet it appears as though students have little knowledge of the health and social care needs and provision outside their local environment. This development will allow for explorative exchange amongst students in three countries, enhancing their understanding of their own and the selected international population health needs and solutions through asking and responding to questions amongst the learning community involved. The connection of the students will be recorded for their use in reflection; of particular interest will be the use of information included by the students to answer questions about their locality. PMID:27332439

  11. The human CD77- B cell population represents a heterogeneous subset of cells comprising centroblasts, centrocytes, and plasmablasts, prompting phenotypical revision.

    PubMed

    Högerkorp, Carl-Magnus; Borrebaeck, Carl A K

    2006-10-01

    The process of becoming an Ig-producing plasma cell takes the mature B cell through the germinal center, where Ig genes are diversified through somatic hypermutation and class switch recombination. To more clearly define functional characteristics of the germinal center dark zone centroblasts and the light zone centrocytes, we have performed expression analysis of the CD77(+) and CD77(-) populations, because CD77 has been accepted as a discriminator of centroblasts and centrocytes. Our results demonstrated that the CD77(+) and the CD77(-) populations lack functional associated expression programs discriminating the two populations. Both populations are shown to be actively cycling and to share common features associated with cell cycle regulation and DNA maintenance. They are also shown to have an equally active DNA repair program, as well as components involved in somatic hypermutation and class switch recombination. Moreover, the data also demonstrated that the CD77(-) population comprises cells with an already initiated plasma cell differentiation program. Together this demonstrates that CD77 does not discriminate centroblasts and centrocytes and that the CD77(-) population represents a heterogeneous subset of cells, comprising centroblasts, centrocytes, and plasmablast. PMID:16982868

  12. Individual-Based Modeling of Tuberculosis in a User-Friendly Interface: Understanding the Epidemiological Role of Population Heterogeneity in a City

    PubMed Central

    Prats, Clara; Montañola-Sales, Cristina; Gilabert-Navarro, Joan F.; Valls, Joaquim; Casanovas-Garcia, Josep; Vilaplana, Cristina; Cardona, Pere-Joan; López, Daniel

    2016-01-01

    For millennia tuberculosis (TB) has shown a successful strategy to survive, making it one of the world’s deadliest infectious diseases. This resilient behavior is based not only on remaining hidden in most of the infected population, but also by showing slow evolution in most sick people. The course of the disease within a population is highly related to its heterogeneity. Thus, classic epidemiological approaches with a top-down perspective have not succeeded in understanding its dynamics. In the past decade a few individual-based models were built, but most of them preserved a top-down view that makes it difficult to study a heterogeneous population. We propose an individual-based model developed with a bottom-up approach to studying the dynamics of pulmonary TB in a certain population, considered constant. Individuals may belong to the following classes: healthy, infected, sick, under treatment, and treated with a probability of relapse. Several variables and parameters account for their age, origin (native or immigrant), immunodeficiency, diabetes, and other risk factors (smoking and alcoholism). The time within each infection state is controlled, and sick individuals may show a cavitated disease or not that conditions infectiousness. It was implemented in NetLogo because it allows non-modelers to perform virtual experiments with a user-friendly interface. The simulation was conducted with data from Ciutat Vella, a district of Barcelona with an incidence of 67 TB cases per 100,000 inhabitants in 2013. Several virtual experiments were performed to relate the disease dynamics with the structure of the infected subpopulation (e.g., the distribution of infected times). Moreover, the short-term effect of health control policies on modifying that structure was studied. Results show that the characteristics of the population are crucial for the local epidemiology of TB. The developed user-friendly tool is ready to test control strategies of disease in any city in the

  13. School Enrollment--Social and Economic Characteristics of Students: October 1986. Current Population Reports: Population Characteristics.

    ERIC Educational Resources Information Center

    Bruno, Rosalind R.

    1988-01-01

    This report presents detailed tabulations of data from the Current Population Survey on school enrollment in October 1986, and summary time series of data collected since the inception of the survey in 1946. School enrollment data are shown by the following personal and school characteristics: (1) age; (2) race; (3) Hispanic origin; (4) sex; (5)…

  14. The effect of homogeneous and heterogeneous review pairs on student achievement and attitude when utilizing computer-assisted instruction in middle-level Earth science classes

    NASA Astrophysics Data System (ADS)

    Lyon, Ellen Beth

    1998-09-01

    This research project investigated the influence of homogeneous (like-ability) review pairs coupled with heterogeneous (mixed-ability) cooperative learning groups using computer-assisted instruction (CAI) on academic achievement and attitude toward science in eighth grade Earth science students. Subjects were placed into academic quartiles (Hi, Med-Hi, Med-Lo, and Lo) based on achievement. Cooperative learning groups of four (one student from each academic quartile) were formed in all classes, within which students completed CAI through a software package entitled Geoscience Education Through Interactive Technology, or GETITspTM. Each day, when computer activities were completed, students in the experimental classes were divided into homogeneous review pairs to review their work. The students in the control classes were divided into heterogeneous review pairs to review their work. The effects of the experimental treatment were measured by pretest, posttest, and delayed posttest measures, by pre- and post-student attitude scales, and by evaluation of amendments students made to their work during the time spent in review pairs. Results showed that student achievement was not significantly influenced by placement in homogeneous or heterogeneous review pairs, regardless of academic quartile assignment. Student attitude toward science as a school subject did not change significantly due to experimental treatment. Achievement retention of students in experimental and control groups within each quartile showed no significant difference. Notebook amendment patterns showed some significant differences in a few categories. For the Hi quartile, there were significant differences in numbers of deletion amendments and substitution amendments between the experimental and the control group. In both cases, subjects in the experimental group (homogeneous review pairs) made greater number of amendments then those in the control group (heterogeneous review pairs). For the Lo quartile

  15. Limits of Generalizing in Education Research: Why Criteria for Research Generalization Should Include Population Heterogeneity and Uses of Knowledge Claims

    ERIC Educational Resources Information Center

    Ercikan, Kadriye; Roth, Wolff-Michael

    2014-01-01

    Context: Generalization is a critical concept in all research designed to generate knowledge that applies to all elements of a unit (population) while studying only a subset of these elements (sample). Commonly applied criteria for generalizing focus on experimental design or representativeness of samples of the population of units. The criteria…

  16. Genome-Wide Association Analysis for Blood Lipid Traits Measured in Three Pig Populations Reveals a Substantial Level of Genetic Heterogeneity

    PubMed Central

    Yang, Hui; Huang, Xiaochang; Zeng, Zhijun; Zhang, Wanchang; Liu, Chenlong; Fang, Shaoming; Huang, Lusheng; Chen, Congying

    2015-01-01

    Serum lipids are associated with myocardial infarction and cardiovascular disease in humans. Here we dissected the genetic architecture of blood lipid traits by applying genome-wide association studies (GWAS) in 1,256 pigs from Laiwu, Erhualian and Duroc × (Landrace × Yorkshire) populations, and a meta-analysis of GWAS in more than 2,400 pigs from five diverse populations. A total of 22 genomic loci surpassing the suggestive significance level were detected on 11 pig chromosomes (SSC) for six blood lipid traits. Meta-analysis of GWAS identified 5 novel loci associated with blood lipid traits. Comparison of GWAS loci across the tested populations revealed a substantial level of genetic heterogeneity for porcine blood lipid levels. We further evaluated the causality of nine polymorphisms nearby or within the APOB gene on SSC3 for serum LDL-C and TC levels. Of the 9 polymorphisms, an indel showed the most significant association with LDL-C and TC in Laiwu pigs. But the significant association was not identified in the White Duroc × Erhualian F2 resource population, in which the QTL for LDL-C and TC was also detected on SSC3. This indicates that population-specific signals may exist for the SSC3 QTL. Further investigations are warranted to validate this assumption. PMID:26121138

  17. Who Are Our Students? Cluster Analysis as a Tool for Understanding Community College Student Populations

    ERIC Educational Resources Information Center

    Ammon, Bridget V.; Bowman, Jamillah; Mourad, Roger

    2008-01-01

    This study showcases cluster analysis as a useful tool for those who seek to understand the types of students their community colleges serve. Although educational goal, academic program, and demographics are often used as descriptive variables, it is unclear which, if any, of these are the best way to classify community college students. Cluster…

  18. Analysis of survival, gene expression and behavior following chill-coma in the medfly Ceratitis capitata: effects of population heterogeneity and age.

    PubMed

    Pujol-Lereis, Luciana Mercedes; Rabossi, Alejandro; Quesada-Allué, Luis Alberto

    2014-12-01

    The medfly Ceratitis capitata is an agricultural pest distributed worldwide thanks, in part, to its phenotypic plasticity of thermal tolerance. Cold exposure has been shown to reduce C. capitata survival, which may affect its distribution in areas with subfreezing temperatures. When insects are increasingly cooled, they attain a critical thermal threshold and enter a chill-coma state characterized by cessation of movement. It is not clear how a rapid cold exposure affects the physiological state of medflies, and how this is influenced by age and population heterogeneity. In order to approach these questions, C. capitata single-sex laboratory populations of 15 and 30 days old were subjected to a chill-coma recovery assay, and separated according to their recovery time in three subgroups: Fast-Subgroups, Intermediate-Subgroups, and Slow-Subgroups. Thereafter, we analyzed their survival, behavioral, and gene expression outputs. In female and old male populations, we found that flies with the slowest recovery time had a reduced life expectancy, a higher initial mortality rate, and a worse climbing performance compared with flies that recovered faster. Therefore, we were able to separate subgroups that developed chilling-injury from subgroups that had a reversible full recovery after cold exposure. The gene expression analysis of the heat shock protein genes hsp70 and hsp83 showed no clear association with the parameters studied. Interestingly, thorax expression levels of the Cu/Zn superoxide dismutase gene were elevated during the recovery phase in the Fast-Subgroups, but remained constant in the Slow-Subgroups that developed chilling-injury. On the other hand, none of the young male subgroups seemed to have suffered irreversible damage. Thus, we concluded that depending on age and population heterogeneity, chill-coma recovery time points out significant differences on individual cold tolerance. Moreover, the inability to properly induce the antioxidant defense system

  19. A Pedagogical Note: Use of Telepractice to Link Student Clinicians to Diverse Populations

    PubMed Central

    CASSEL, STACY GALLESE; HADLEY EDD, AMY J.

    2016-01-01

    Telepractice is the application of telecommunications technology to the delivery of telehealth services via the online connection of clinicians, clients, and patients for assessment, intervention, or consultation. This article describes a pilot project in which speech-language pathology students in a university training program gained experience in working with culturally diverse preschool students using telepractice technology. The preschool students benefited by making gains in communication skills, while the university students acquired competency in the use of telepractice and in working with children whose cultural and linguistic backgrounds were outside of their experience. To assess the training experience, a Likert-scale survey administered to student clinicians revealed a high degree of satisfaction and improved familiarity with the use of telepractice, and an increased comfort level working with multi-cultural populations. PMID:27563390

  20. A Pedagogical Note: Use of Telepractice to Link Student Clinicians to Diverse Populations.

    PubMed

    Cassel, Stacy Gallese; Hadley Edd, Amy J

    2016-01-01

    Telepractice is the application of telecommunications technology to the delivery of telehealth services via the online connection of clinicians, clients, and patients for assessment, intervention, or consultation. This article describes a pilot project in which speech-language pathology students in a university training program gained experience in working with culturally diverse preschool students using telepractice technology. The preschool students benefited by making gains in communication skills, while the university students acquired competency in the use of telepractice and in working with children whose cultural and linguistic backgrounds were outside of their experience. To assess the training experience, a Likert-scale survey administered to student clinicians revealed a high degree of satisfaction and improved familiarity with the use of telepractice, and an increased comfort level working with multi-cultural populations. PMID:27563390

  1. Tumour Cell Heterogeneity

    PubMed Central

    Gay, Laura; Baker, Ann-Marie; Graham, Trevor A.

    2016-01-01

    The population of cells that make up a cancer are manifestly heterogeneous at the genetic, epigenetic, and phenotypic levels. In this mini-review, we summarise the extent of intra-tumour heterogeneity (ITH) across human malignancies, review the mechanisms that are responsible for generating and maintaining ITH, and discuss the ramifications and opportunities that ITH presents for cancer prognostication and treatment. PMID:26973786

  2. Integrating Vocational & Academic Education. A Handbook Featuring Four Demonstration Sites Including Students from Special Populations.

    ERIC Educational Resources Information Center

    Tindall, Lloyd W.; And Others

    This handbook describes the processes and techniques used to develop, implement, and evaluate four integrated vocational and academic learning programs in Wisconsin that included students from special populations. The handbook contains seven chapters. Chapter 1 presents an overview of the project, including the request for proposal process and…

  3. Assessing Undergraduate Learning Outcomes between Accelerated Degree and Traditional Student Populations

    ERIC Educational Resources Information Center

    Rawls, Janita; Hammons, Stacy

    2012-01-01

    This study investigated learning outcomes in both traditional and accelerated degree populations. Using the National Survey of Student Engagement, outcomes were examined relating to critical thinking, oral and written communication, and cultural and global understanding. Literature from life stage development and degree delivery mode areas were…

  4. Generalizing in Interaction: Middle School Mathematics Students Making Mathematical Generalizations in a Population-Modeling Project

    ERIC Educational Resources Information Center

    Jurow, A. Susan

    2004-01-01

    Generalizing or making claims that extend beyond particular situations is a central mathematical practice and a focus of classroom mathematics instruction. This study examines how aspects of generality are produced through the situated activities of a group of middle school mathematics students working on an 8-week population-modeling project. The…

  5. Evaluation of the Technical Evidence of Assessments for Special Student Populations

    ERIC Educational Resources Information Center

    Sato, Edynn; Rabinowitz, Stanley; Worth, Peter; Gallagher, Carole; Lagunoff, Rachel; Crane, Eric

    2007-01-01

    Recent research has shown that the technical adequacy of assessments for special student populations is relatively undeveloped compared to their general education counterparts; that is, the technical evidence provided and the methods by which this evidence is established do not necessarily account for the unique characteristics of special needs…

  6. Validity of Personal Growth Initiative Scale Scores with a Mexican American College Student Population

    ERIC Educational Resources Information Center

    Robitschek, Christine

    2003-01-01

    This study tested the validity of scores on the Personal Growth Initiative Scale (PGIS; C. Robitschek, 1998, 1999) with a Mexican American college student sample. Results indicated that the PGIS scores appear to be culturally relevant for this population, with scores on the PGIS having many similar relations with other variables that have been…

  7. Teaching Population Balances for Chemical Engineering Students: Application to Granulation Processes

    ERIC Educational Resources Information Center

    Bucala, Veronica; Pina, Juliana

    2007-01-01

    The population balance equation (PBE) is a useful tool to predict particle size distributions in granulation processes. When PBE is taught to advanced chemical engineering students, the internal coordinates (particle properties) are particularly hard to understand. In this paper, the flow of particles along different coordinates is carefully…

  8. Experiences of the Student Population at an Urban University: How Do They Use a Joint Library?

    ERIC Educational Resources Information Center

    Molteni, Valeria E.; Goldman, Crystal; Oulc'hen, Enora

    2014-01-01

    The King Library in San José, California, is a unique combination of academic and public library. It serves the diverse populations of the City of San José and San José State University (SJSU). This article provides analysis of data collected in a study on the concept of "library as place" and SJSU students' sense of belonging…

  9. The Effectiveness of "Study Unlimited" in Serving New Student Populations in the Community.

    ERIC Educational Resources Information Center

    Stevens, Mary A.

    This study evaluates the effectiveness of Study Unlimited, an off-campus instructional program cooperatively offered at area public libraries by Black Hawk College and the River Bend Library System (Illinois), in serving "new" student populations (adults over 25, males employed full-time, housewives, ethnic minorities, and adults attending college…

  10. The Distribution of and Relationship between Autistic Traits and Social Anxiety in a UK Student Population

    ERIC Educational Resources Information Center

    Freeth, Megan; Bullock, Tom; Milne, Elizabeth

    2013-01-01

    Traits associated with autism and social anxiety were assessed in a UK student population (n = 1325) using the Autism-spectrum Quotient and the Liebowitz Social Anxiety Scale. Clinically relevant levels of autistic traits were observed in 3.3% of the cohort; 10.1% of the cohort reported clinically relevant levels of social anxiety; 1.8% of the…

  11. Self-reported symptoms of temporomandibular dysfunction in a female university student population in Saudi Arabia.

    PubMed

    Zulqarnain, B J; Khan, N; Khattab, S

    1998-12-01

    The symptoms of temporomandibular dysfunction (TMD), reported by 705 female university students of Riyadh, Saudi Arabia, are analysed. The population is representative of the educated class of Saudi Arabia. The most frequently reported symptoms were jaw feeling tired (34.5%), awareness of uncomfortable bite (31.3%), pain in front of the ear (22.4%) and discomfort upon wide opening (22.4%). The frequency of subjective reactions was, pain interferes with activity (42%), disturbed sleep (40.6%), taking of medication (27.8%) and pain being frustrating or depressing (26.8%). Some interesting relationships were found between the reported symptoms and marital status, residence and college of education. These findings are similar to those reported in a Bedouin community in Egypt, but lower than that in a Saudi Arabian population attending dental clinics, Saudi male dental students and high school students. PMID:9888230

  12. Clinical utility of urine neutrophil gelatinase-associated lipocalin measured at admission to predict outcomes in heterogeneous population of critically ill patients

    PubMed Central

    Nayak, N. M.; Madhumitha, S.; Annigeri, R. A.; Venkataraman, R.; Balasubramaian, S.; Seshadri, R.; Vadamalai, V.; Rao, B. S.; Kowdle, P. C.; Ramakrishnan, N.; Mani, M. K.

    2016-01-01

    Urine neutrophil gelatinase-associated lipocalin (uNGAL) is a reliable early biomarker of acute kidney injury (AKI) in a homogeneous patient population. However, its utility in a heterogeneous population of critically ill, in whom the time of onset of renal insult is often unclear, is not clearly established. We evaluated the ability of a single measurement of uNGAL in a heterogeneous adult population, on admission to intensive care unit (ICU), to predict the occurrence of AKI and hospital mortality. One hundred and two consecutive adult patients had uNGAL measured within 8 h of admission to ICU. The demographic and laboratory data were collected at admission. The diagnosis of AKI was based on AKI Network (AKIN) criteria. The primary outcome was the development of AKI, and the secondary outcome was hospital mortality. The mean age was 54 ± 16.4 years and 65% were males. Urine NGAL (ng/ml) was 69 ± 42 in patients with AKI (n = 42) and 30.4 ± 41.7 in those without AKI (P < 0.001). The area under the receiver operating characteristic (ROC) curve for prediction of AKI was 0.79 and for serum creatinine (SCr) was 0.88. The sensitivity and specificity for a cut-off value of uNGAL of 75 ng/ml to predict AKI were 0.5 and 0.85 respectively. uNGAL > 75 ng/ml was a strong (odd ratio = 5.17, 95% confidence interval: 1.39–19.3) and independent predictor of hospital mortality. A single measurement of uNGAL at admission to ICU exhibited good predictive ability for AKI though the sensitivity was low. The predictive ability of uNGAL was inferior to simultaneously measured SCr at admission, hence limited its clinical utility to predict AKI. However, admission uNGAL was a strong, independent predictor of hospital mortality. PMID:27051136

  13. Integrating collaborative population health projects into a medical student curriculum at Stanford.

    PubMed

    Chamberlain, Lisa J; Wang, N Ewen; Ho, Evelyn T; Banchoff, Ann W; Braddock, Clarence H; Gesundheit, Neil

    2008-04-01

    The authors describe the population health curriculum at the Stanford University School of Medicine from 2003 to 2007 that includes a requirement for first-year medical students to engage in community-based population health projects. The new curriculum in population health comprises classroom and experiential teaching methods. Population health projects, a key component of the curriculum, are described and classified by topic and topic area (e.g., health education; health services) and the intended outcome of the intervention (e.g., establishing new policies; advocacy). During the past four years, 344 students have entered the curriculum and have participated in 68 population health projects. The projects were determined both by students' interests and community needs, and they represented diverse topics: 51% of the 68 projects addressed topics in the area of disease prevention and health promotion; 28% addressed health care access; 15% addressed health services; 4% addressed emergency preparedness; and 1% addressed ethical issues in health. Each project had one of three targets for intervention: community capacity building, establishing policies and engaging in advocacy, and bringing about change or improvement in an aspect of the health care system. Projects represented diverse stages in the evolution of a community-campus partnership, from needs assessment to planning, implementation, and evaluation of project outcomes. Experience to date shows that classroom-based sessions and experiential learning in the area of population health can be successfully integrated in a medical school curriculum. When contextualized in a population health curriculum, population health projects can provide future physicians with an experiential counterpart to their classroom learning. PMID:18367891

  14. Joint QTL analyses for partial resistance to Phytophthora sojae using six nested inbred populations with heterogeneous conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Partial resistance to Phytophthora sojae in soybean is controlled by multiple quantitative trait loci (QTL). With traditional QTL mapping approaches, power to detect these QTL, frequently of small effect, can be limited by population size. Joint linkage QTL analysis of nested recombinant inbred li...

  15. A Survey to Identify University Student Attitudes toward the Role of Government in Controlling Human Population Growth.

    ERIC Educational Resources Information Center

    Yost, Thomas E.

    The purpose of this study was to obtain, measure, and evaluate the attitudes of postsecondary students on domestic population issues in order to determine the extent of support for a national government-controlled population stabilization program. A total of 125 students enrolled in either the American government or general sociology course at the…

  16. Method to purify and analyze heterogeneous senescent cell populations using a microfluidic filter with uniform fluidic profile.

    PubMed

    Kim, Minseok S; Jo, Seonghyeon; Park, Joon Tae; Shin, Hyun Young; Kim, Sun Soo; Gurel, Ogan; Park, Sang Chul

    2015-10-01

    To precisely purify and study aged (senescent) cells, we have designed, fabricated, and demonstrated a novel diamond-structure (DS) microfluidic filter. Nonuniform flow velocities within the microfilter channel can compromise microfluidic filter performance, but with this new diamond structure, further optimized via simulation, we achieve a uniform microfilter flow field, improving the throughput of size-based separation of senescent cells, as obtained by 39-passaged human dermal fibroblasts. After separating these aged cells into two groups, consisting of large- and small-sized cells, we assessed senescence by measuring lipofuscin accumulation and β-galactosidase activity. Our results reveal that even though these senescent cells had been equivalently passaged in culture, a high degree of size distribution and senescent phenotype heterogeneity was observed. In particular, the smaller-sized cells tended to express a younger phenotype while the larger aged cells demonstrated an older phenotype. We suggest that size-based separation of senescent cells, subtyped into small- and large-sized cohorts, offers an alternative method to purify such aged cells, thereby enabling more precise study of the mechanisms of aging, autophagy impairment, and rejuvenation. PMID:26322520

  17. Enrichment of live unlabelled cardiomyocytes from heterogeneous cell populations using manipulation of cell settling velocity by magnetic field

    PubMed Central

    Sofla, Aarash; Cirkovic, Bojana; Hsieh, Anne; Miklas, Jason W.; Filipovic, Nenad; Radisic, Milica

    2013-01-01

    The majority of available cardiomyocyte markers are intercellular proteins, limiting our ability to enrich live cardiomyocytes from heterogeneous cell preparations in the absence of genetic labeling. Here, we describe enrichment of live cardiomyocytes from the hearts of adult mice in a label-free microfluidic approach. The separation device consisted of a vertical column (15 mm long, 700 μm diameter), placed between permanent magnets resulting in a field strength of 1.23 T. To concentrate the field at the column wall, the column was wrapped with 69 μm diameter nickel wire. Before passing the cells through the column, the cardiomyocytes in the cell suspension had been rendered paramagnetic by treatment of the adult mouse heart cell preparation with sodium nitrite (2.5 mM) for 20 min on ice. The cell suspension was loaded into the vertical column from the top and upon settling, the non-myocytes were removed by the upward flow from the column. The cardiomyocytes were then collected from the column by applying a higher flow rate (144 μl/min). We found that by applying a separation flow rate of 4.2 μl/min in the first step, we can enrich live adult cardiomyocytes to 93% ± 2% in a label-free manner. The cardiomyocytes maintained viability immediately after separation and upon 24 h in culture. PMID:24404002

  18. Digital Sorting of Pure Cell Populations Enables Unambiguous Genetic Analysis of Heterogeneous Formalin-Fixed Paraffin-Embedded Tumors by Next Generation Sequencing

    PubMed Central

    Bolognesi, Chiara; Forcato, Claudio; Buson, Genny; Fontana, Francesca; Mangano, Chiara; Doffini, Anna; Sero, Valeria; Lanzellotto, Rossana; Signorini, Giulio; Calanca, Alex; Sergio, Maximilian; Romano, Rita; Gianni, Stefano; Medoro, Gianni; Giorgini, Giuseppe; Morreau, Hans; Barberis, Massimo; Corver, Willem E.; Manaresi, Nicolò

    2016-01-01

    Precision medicine in oncology requires an accurate characterization of a tumor molecular profile for patient stratification. Though targeted deep sequencing is an effective tool to detect the presence of somatic sequence variants, a significant number of patient specimens do not meet the requirements needed for routine clinical application. Analysis is hindered by contamination of normal cells and inherent tumor heterogeneity, compounded with challenges of dealing with minute amounts of tissue and DNA damages common in formalin-fixed paraffin-embedded (FFPE) specimens. Here we present an innovative workflow using DEPArray™ system, a microchip-based digital sorter to achieve 100%-pure, homogenous subpopulations of cells from FFPE samples. Cells are distinguished by fluorescently labeled antibodies and DNA content. The ability to address tumor heterogeneity enables unambiguous determination of true-positive sequence variants, loss-of-heterozygosity as well as copy number variants. The proposed strategy overcomes the inherent trade-offs made between sensitivity and specificity in detecting genetic variants from a mixed population, thus rescuing for analysis even the smaller clinical samples with low tumor cellularity. PMID:26864208

  19. Stochasticity in space, persistence in time: genetic heterogeneity in harbour populations of the introduced ascidian Styela plicata

    PubMed Central

    Pineda, Mari-Carmen; Lorente, Beatriz; López-Legentil, Susanna; Palacín, Creu

    2016-01-01

    Spatio-temporal changes in genetic structure among populations provide crucial information on the dynamics of secondary spread for introduced marine species. However, temporal components have rarely been taken into consideration when studying the population genetics of non-indigenous species. This study analysed the genetic structure of Styela plicata, a solitary ascidian introduced in harbours and marinas of tropical and temperate waters, across spatial and temporal scales. A fragment of the mitochondrial gene Cytochrome Oxidase subunit I (COI) was sequenced from 395 individuals collected at 9 harbours along the NW Mediterranean coast and adjacent Atlantic waters (> 1,200 km range) at two time points 5 years apart (2009 and 2014). The levels of gene diversity were relatively low for all 9 locations in both years. Analyses of genetic differentiation and distribution of molecular variance revealed strong genetic structure, with significant differences among many populations, but no significant differences among years. A weak and marginally significant correlation between geographic distance and gene differentiation was found. Our results revealed spatial structure and temporal genetic homogeneity in S. plicata, suggesting a limited role of recurrent, vessel-mediated transport of organisms among small to medium-size harbours. Our study area is representative of many highly urbanized coasts with dense harbours. In these environments, the episodic chance arrival of colonisers appears to determine the genetic structure of harbour populations and the genetic composition of these early colonising individuals persists in the respective harbours, at least over moderate time frames (five years) that encompass ca. 20 generations of S. plicata. PMID:27366653

  20. Stochasticity in space, persistence in time: genetic heterogeneity in harbour populations of the introduced ascidian Styela plicata.

    PubMed

    Pineda, Mari-Carmen; Lorente, Beatriz; López-Legentil, Susanna; Palacín, Creu; Turon, Xavier

    2016-01-01

    Spatio-temporal changes in genetic structure among populations provide crucial information on the dynamics of secondary spread for introduced marine species. However, temporal components have rarely been taken into consideration when studying the population genetics of non-indigenous species. This study analysed the genetic structure of Styela plicata, a solitary ascidian introduced in harbours and marinas of tropical and temperate waters, across spatial and temporal scales. A fragment of the mitochondrial gene Cytochrome Oxidase subunit I (COI) was sequenced from 395 individuals collected at 9 harbours along the NW Mediterranean coast and adjacent Atlantic waters (> 1,200 km range) at two time points 5 years apart (2009 and 2014). The levels of gene diversity were relatively low for all 9 locations in both years. Analyses of genetic differentiation and distribution of molecular variance revealed strong genetic structure, with significant differences among many populations, but no significant differences among years. A weak and marginally significant correlation between geographic distance and gene differentiation was found. Our results revealed spatial structure and temporal genetic homogeneity in S. plicata, suggesting a limited role of recurrent, vessel-mediated transport of organisms among small to medium-size harbours. Our study area is representative of many highly urbanized coasts with dense harbours. In these environments, the episodic chance arrival of colonisers appears to determine the genetic structure of harbour populations and the genetic composition of these early colonising individuals persists in the respective harbours, at least over moderate time frames (five years) that encompass ca. 20 generations of S. plicata. PMID:27366653

  1. Understanding the Cultural-Linguistic Divide in American Classrooms: Language Learning Strategies for a Diverse Student Population

    ERIC Educational Resources Information Center

    Holmes, Kerry P.; Rutledge, Susan; Gauthier, Lane Roy

    2009-01-01

    This article addresses critical factors that impact learning for a growing population of students in American classrooms, the English Language Learner (ELL). Even in the smallest school districts, it is common for teachers to have one or more students with limited or no command of the English language in their classrooms. Many students in schools…

  2. Two Test Items to Explore High School Students' Beliefs of Sample Size When Sampling from Large Populations

    ERIC Educational Resources Information Center

    Bill, Anthony; Henderson, Sally; Penman, John

    2010-01-01

    Two test items that examined high school students' beliefs of sample size for large populations using the context of opinion polls conducted prior to national and state elections were developed. A trial of the two items with 21 male and 33 female Year 9 students examined their naive understanding of sample size: over half of students chose a…

  3. Variance associated with the use of relative velocity for force platform gait analysis in a heterogeneous population of clinically normal dogs.

    PubMed

    Volstad, Nicola; Nemke, Brett; Muir, Peter

    2016-01-01

    Factors that contribute to variance in ground reaction forces (GRFs) include dog morphology, velocity, and trial repetition. Narrow velocity ranges are recommended to minimize variance. In a heterogeneous population, it may be preferable to minimize data variance and efficiently perform force platform gait analysis by evaluation of each individual dog at its preferred velocity, such that dogs are studied at a similar relative velocity (V*). Data from 27 normal dogs were obtained including withers and shoulder height. Each dog was trotted across a force platform at its preferred velocity, with controlled acceleration (±0.5 m/s(2)). V* ranges were created for withers and shoulder height. Variance effects from 12 trotting velocity ranges and associated V* ranges were examined using repeated-measures analysis-of-covariance. Mean bodyweight was 24.4 ± 7.4 kg. Individual dog, velocity, and V* significantly influenced GRF (P <0.001). Trial number significantly influenced thoracic limb peak vertical force (PVF) (P <0.001). Limb effects were not significant. The magnitude of variance effects was greatest for the dog effect. Withers height V* was associated with small GRF variance. Narrow velocity ranges typically captured a smaller percentage of trials and were not consistently associated with lower variance. The withers height V* range of 0.6-1.05 captured the largest proportion of trials (95.9 ± 5.9%) with no significant effects on PVF and vertical impulse. The use of individual velocity ranges derived from a withers height V* range of 0.6-1.05 will account for population heterogeneity while minimizing exacerbation of lameness in clinical trials studying lame dogs by efficient capture of valid trials. PMID:26631945

  4. Embedding Evolution: Exploring Changes in Students' Conceptual Development, Beliefs, and Motivations in a Population Ecology Unit

    NASA Astrophysics Data System (ADS)

    Rose, Nancy L.

    The purpose of this study was to explore student changes in conceptual development, epistemology, and motivations when evolution concepts are embedded and explicit reflective discourse is used in a unit for population ecology. The two research problems were: (1) What changes are observed in student's conceptual development, epistemology, and motivations when there is explicit reflective discourse within a population ecology unit with embedded evolution?, and (2) In what ways does explicit reflection influence students' mental models within a population ecology unit with embedded evolution? This mixed-method, quasi-experimental study assessed two regular high school biology classes in a small, urban, Midwestern high school. Students in this study had not studied evolution within any formal chapters, but had been immersed in a curriculum with embedded evolution. The study was conducted over a four-week period in a population ecology unit near the beginning of second semester. Instruction emphasized basic conceptions in population ecology. Five key intervention activities included evolutionary concepts as part of an embedded curriculum. The independent variable was explicit reflective discourse with one or two intervention questions after completion of these activities. Data included pre- and posttest surveys measuring (a) evolutionary understanding of natural selection, (b) science beliefs, and (c) science motivations. Written artifacts included (a) explanations to scenarios, (b) pre- and post-argument reflections revealing student's science beliefs and science motivations resultant from two argumentations, and (c) three, pre-, post-, and 6-week final concept maps constructed from 12 concepts. All data sources provided descriptive data. Conceptual change was interpreted from an ontological, epistemological, and motivational perspective. The experimental class receiving explicit reflective discourse showed greater overall increases in conceptual development. Students

  5. [Attitudes of Costa Rican students and teachers on sex and population education].

    PubMed

    Stycos, J M

    1987-01-01

    Students in 34 secondary schools and the last year of primary school throughout Costa Rica were interviewed to determine the attitudes of older students toward sex and population education. The sex, grade level, and geographic region of residence were considered key study variables. To ensure an adequate number of cases in each geographic region, the sample was stratified into 4 zones: downtown San Jose, the rest of metropolitan San Jose, other cantons of the central valley, and cantons outside the central valley. Various smaller studies were also conducted, including brief intelligence tests for 190 students, interviews with 286 parents, focus group debates in 8 schools, surveys of 10 teachers in each school, and interviews with Ministry of Education and other officials. The final questionnaire was very long, consisting of 281 questions as well as data about the student's residence. Although students cooperated in filling out the questionnaires, it was too long and 27% of all students failed to complete it. The average student completed 91% of the questions, but fewer than 1/2 of the 6th year primary students were able to complete it. Costa Rican students gain at least a partial understanding of sex at an early age. Almost all secondary students and 71% of the 6th year primary students knew 1 or more contraceptive methods. Most acquired contraceptive information before the age of 12, often from the mass media. 2/3 said their parents had been important sources of information on sex. Most students said they had received some information on sex or family planning in school, but no influence was seen on knowledge or attitudes. The survey results revealed considerable misinformation about sex and family planning. The attitude of Costa Rican students toward equality of the sexes appears conservative, but it becomes less so as their grade level advances, especially for girls. The majority of students had tolerant or indifferent attitudes toward premarital fertility, the

  6. Benchmarking Student Diversity at Public Universities in the United States: Accounting for State Population Composition

    PubMed Central

    Franklin, Rachel S.

    2014-01-01

    Regions rely at least partially on the internal production of a qualified workforce in order to maintain their economic competitiveness. Increasingly, at least from a university or corporate point of view, a qualified workforce is viewed as one that is racially and ethnically diverse. However, the conceptualization and measurement of ethnic and racial diversity in higher education appears to be often based on normative values rather than solid benchmarks, making any regional comparisons or goals difficult to specify. Ideally, at least as a starting point, public state universities would, while attempting to increase overall student diversity, benchmark their progress against the state population composition. This paper combines enrollment data from the National Center for Education Statistics (NCES) with U.S. Census Bureau population estimates data to provide a point of comparison for state universities. The paper has two goals: first a university-level comparison of diversity scores, as measured by the interaction index and, second, an analysis of how university student population composition compares to that of the population the university was originally intended to serve – the state population. PMID:25506123

  7. Heterogeneous Expression of T-type Ca2+ Channels Defines Different Neuronal Populations in the Inferior Olive of the Mouse

    PubMed Central

    Bazzigaluppi, Paolo; de Jeu, Marcel T. G.

    2016-01-01

    The neurons in the inferior olive express subthreshold oscillations in their membrane potential. This oscillatory activity is known to drive synchronous activity in the cerebellar cortex and plays a role in motor learning and motor timing. In the past years, it was commonly thought that olivary neurons belonged to a unique population of oscillating units and that oscillation properties were exclusively dependent on network settings and/or synaptic inputs. The origin of olivary oscillations is now known to be a local phenomenon and is generated by a combination of conductances. In the present work, we show the existence of at least two neuronal populations that can be distinguished on the basis of the presence or absence of low-voltage activated Ca2+ channels. The expression of this channel determines the oscillatory behavior of olivary neurons. Furthermore, the number of cells that express this channel is different between sub nuclei of the inferior olive. These findings clearly indicate the functional variability within and between olivary sub nuclei. PMID:27540355

  8. Heterogeneous Expression of T-type Ca(2+) Channels Defines Different Neuronal Populations in the Inferior Olive of the Mouse.

    PubMed

    Bazzigaluppi, Paolo; de Jeu, Marcel T G

    2016-01-01

    The neurons in the inferior olive express subthreshold oscillations in their membrane potential. This oscillatory activity is known to drive synchronous activity in the cerebellar cortex and plays a role in motor learning and motor timing. In the past years, it was commonly thought that olivary neurons belonged to a unique population of oscillating units and that oscillation properties were exclusively dependent on network settings and/or synaptic inputs. The origin of olivary oscillations is now known to be a local phenomenon and is generated by a combination of conductances. In the present work, we show the existence of at least two neuronal populations that can be distinguished on the basis of the presence or absence of low-voltage activated Ca(2+) channels. The expression of this channel determines the oscillatory behavior of olivary neurons. Furthermore, the number of cells that express this channel is different between sub nuclei of the inferior olive. These findings clearly indicate the functional variability within and between olivary sub nuclei. PMID:27540355

  9. An Individual-Based Model of the Evolution of Pesticide Resistance in Heterogeneous Environments: Control of Meligethes aeneus Population in Oilseed Rape Crops

    PubMed Central

    Stratonovitch, Pierre; Elias, Jan; Denholm, Ian; Slater, Russell; Semenov, Mikhail A.

    2014-01-01

    Preventing a pest population from damaging an agricultural crop and, at the same time, preventing the development of pesticide resistance is a major challenge in crop protection. Understanding how farming practices and environmental factors interact with pest characteristics to influence the spread of resistance is a difficult and complex task. It is extremely challenging to investigate such interactions experimentally at realistic spatial and temporal scales. Mathematical modelling and computer simulation have, therefore, been used to analyse resistance evolution and to evaluate potential resistance management tactics. Of the many modelling approaches available, individual-based modelling of a pest population offers most flexibility to include and analyse numerous factors and their interactions. Here, a pollen beetle (Meligethes aeneus) population was modelled as an aggregate of individual insects inhabiting a spatially heterogeneous landscape. The development of the pest and host crop (oilseed rape) was driven by climatic variables. The agricultural land of the landscape was managed by farmers applying a specific rotation and crop protection strategy. The evolution of a single resistance allele to the pyrethroid lambda cyhalothrin was analysed for different combinations of crop management practices and for a recessive, intermediate and dominant resistance allele. While the spread of a recessive resistance allele was severely constrained, intermediate or dominant resistance alleles showed a similar response to the management regime imposed. Calendar treatments applied irrespective of pest density accelerated the development of resistance compared to ones applied in response to prescribed pest density thresholds. A greater proportion of spring-sown oilseed rape was also found to increase the speed of resistance as it increased the period of insecticide exposure. Our study demonstrates the flexibility and power of an individual-based model to simulate how farming

  10. Genetic heterogeneity among the Hindus and their relationships with the other "Caucasoid" populations: new data on Punjab-Haryana and Rajasthan Indian states.

    PubMed

    Tartaglia, M; Scacchi, R; Corbo, R M; Pompei, F; Rickards, O; Ciminelli, B M; Sangatramani, T; Vyas, M; Dash, S; Modiano, G

    1995-11-01

    The genetic structure of Rajasthan Hindus and Punjab-Haryana Hindus and Sikhs has been studied for ABO, RH, APOC2, C6, C7, F13A, F13B, HP, ORM1, ACP1, ADA, AK1, ESD, GLO1, PGD, PGM1 subtyping, and PGP. This is the first genetic survey on Hindus of Rajasthan. Furthermore, many of these markers have never been studied on Hindus before (APOC2, C6, C7, F13A, F13B, ORM1, PGP). These data, together with those previously available for Hindus, have been utilized to analyze the within-Hindus genetic heterogeneity by RST statistic and correspondence analysis. The genetic relationships of Hindus to other Causcasoid populations were also investigated. In the first analysis, two eastern states (Orissa and Andhra Pradesh) were found to be quite separate from each other and clearly distinct from the northwestern and western states. Out of the markers which could not be utilized in this analysis, PGM1 subtyping turned out to discriminate between the Dravidian-speaking and the Indo-Aryan-speaking Hindus. The second analysis shows a clear-cut separation of Hindus from Europeans, with Near Eastern and Middle Eastern populations genetically in an intermediate position. PMID:8572153

  11. Landscape Effects of a Non-Native Grass Facilitate Source Populations of a Native Generalist Bug, Stenotus rubrovittatus, in a Heterogeneous Agricultural Landscape

    PubMed Central

    Yoshioka, A.; Takada, M. B.; Washitani, I.

    2014-01-01

    Non-native plant species can provide native generalist insects, including pests, with novel food and habitats. It is hypothesized that local and landscape-level abundances of non-native plants can affect the population size of generalist insects, although generalists are assumed to be less sensitive to habitat connectivity than specialists. In a heterogeneous landscape in Japan, the relationship between the density of a native pest of rice (Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae)) and the abundance of Italian ryegrass (Lolium multiflorum Lam. (Poales: Poaceae)), a non-native meadow grass known to facilitate S. rubrovittatus, was analyzed. Statistical analyses of data on bug density, vegetation, and the spatial distribution of fallow fields and meadows dominated by Italian ryegrass, obtained by field surveys, demonstrated that local and landscape-level abundances of Italian ryegrass (the unmowed meadow areas within a few hundred meters of a sampling plot) positively affected bug density before its immigration into rice fields. Our findings suggest that a generalist herbivorous insect that prefers non-native plants responds to spatial availability and connectivity of plant species patches at the metapopulation level. Fragmentation by selective mowing that decreases the total area of source populations and increases the isolation among them would be an effective and environmentally-friendly pest management method. PMID:25205015

  12. Prevalence and Dynamics of Ribosomal DNA Micro-heterogeneity Are Linked to Population History in Two Contrasting Yeast Species

    PubMed Central

    James, Stephen A.; West, Claire; Davey, Robert P.; Dicks, Jo; Roberts, Ian N.

    2016-01-01

    Despite the considerable number and taxonomic breadth of past and current genome sequencing projects, many of which necessarily encompass the ribosomal DNA, detailed information on the prevalence and evolutionary significance of sequence variation in this ubiquitous genomic region are severely lacking. Here, we attempt to address this issue in two closely related yet contrasting yeast species, the baker’s yeast Saccharomyces cerevisiae and the wild yeast Saccharomyces paradoxus. By drawing on existing datasets from the Saccharomyces Genome Resequencing Project, we identify a rich seam of ribosomal DNA sequence variation, characterising 1,068 and 970 polymorphisms in 34 S. cerevisiae and 26 S. paradoxus strains respectively. We discover the two species sets exhibit distinct mutational profiles. Furthermore, we show for the first time that unresolved rDNA sequence variation resulting from imperfect concerted evolution of the ribosomal DNA region follows a U-shaped allele frequency distribution in each species, similar to loci that evolve under non-concerted mechanisms but arising through rather different evolutionary processes. Finally, we link differences between the shapes of these allele frequency distributions to the two species’ contrasting population histories. PMID:27345953

  13. Using heterogeneity in the population structure of U.S. swine farms to compare transmission models for porcine epidemic diarrhoea

    PubMed Central

    O’Dea, Eamon B.; Snelson, Harry; Bansal, Shweta

    2016-01-01

    In 2013, U.S. swine producers were confronted with the disruptive emergence of porcine epidemic diarrhoea (PED). Movement of animals among farms is hypothesised to have played a role in the spread of PED among farms. Via this or other mechanisms, the rate of spread may also depend on the geographic density of farms and climate. To evaluate such effects on a large scale, we analyse state-level counts of outbreaks with variables describing the distribution of farm sizes and types, aggregate flows of animals among farms, and an index of climate. Our first main finding is that it is possible for a correlation analysis to be sensitive to transmission model parameters. This finding is based on a global sensitivity analysis of correlations on simulated data that included a biased and noisy observation model based on the available PED data. Our second main finding is that flows are significantly associated with the reports of PED outbreaks. This finding is based on correlations of pairwise relationships and regression modeling of total and weekly outbreak counts. These findings illustrate how variation in population structure may be employed along with observational data to improve understanding of disease spread. PMID:26947420

  14. Prevalence and Dynamics of Ribosomal DNA Micro-heterogeneity Are Linked to Population History in Two Contrasting Yeast Species.

    PubMed

    James, Stephen A; West, Claire; Davey, Robert P; Dicks, Jo; Roberts, Ian N

    2016-01-01

    Despite the considerable number and taxonomic breadth of past and current genome sequencing projects, many of which necessarily encompass the ribosomal DNA, detailed information on the prevalence and evolutionary significance of sequence variation in this ubiquitous genomic region are severely lacking. Here, we attempt to address this issue in two closely related yet contrasting yeast species, the baker's yeast Saccharomyces cerevisiae and the wild yeast Saccharomyces paradoxus. By drawing on existing datasets from the Saccharomyces Genome Resequencing Project, we identify a rich seam of ribosomal DNA sequence variation, characterising 1,068 and 970 polymorphisms in 34 S. cerevisiae and 26 S. paradoxus strains respectively. We discover the two species sets exhibit distinct mutational profiles. Furthermore, we show for the first time that unresolved rDNA sequence variation resulting from imperfect concerted evolution of the ribosomal DNA region follows a U-shaped allele frequency distribution in each species, similar to loci that evolve under non-concerted mechanisms but arising through rather different evolutionary processes. Finally, we link differences between the shapes of these allele frequency distributions to the two species' contrasting population histories. PMID:27345953

  15. Addressing the Needs of Racially/Culturally Diverse Student Populations in Higher Education: An Analysis of Educational Practices for Disadvantaged Youth

    ERIC Educational Resources Information Center

    Pender, Matea

    2010-01-01

    The recent growth in the racial and cultural heterogeneity of college students in the United States has increased the demand for higher educational policies that will accommodate the needs of an increasingly diverse collective student body (Kao & Thompson, 2003). Traditionally, underrepresented minority students (i.e., African American, Hispanic…

  16. Molecular Heterogeneity in a Patient-Derived Glioblastoma Xenoline Is Regulated by Different Cancer Stem Cell Populations

    PubMed Central

    Garner, Jo Meagan; Ellison, David W.; Finkelstein, David; Ganguly, Debolina; Du, Ziyun; Sims, Michelle; Yang, Chuan He; Interiano, Rodrigo B.; Davidoff, Andrew M.; Pfeffer, Lawrence M.

    2015-01-01

    Malignant glioblastoma (GBM) is a highly aggressive brain tumor with a dismal prognosis and limited therapeutic options. Genomic profiling of GBM samples has identified four molecular subtypes (Proneural, Neural, Classical and Mesenchymal), which may arise from different glioblastoma stem-like cell (GSC) populations. We previously showed that adherent cultures of GSCs grown on laminin-coated plates (Ad-GSCs) and spheroid cultures of GSCs (Sp-GSCs) had high expression of stem cell markers (CD133, Sox2 and Nestin), but low expression of differentiation markers (βIII-tubulin and glial fibrillary acid protein). In the present study, we characterized GBM tumors produced by subcutaneous and intracranial injection of Ad-GSCs and Sp-GSCs isolated from a patient-derived xenoline. Although they formed tumors with identical histological features, gene expression analysis revealed that xenografts of Sp-GSCs had a Classical molecular subtype similar to that of bulk tumor cells. In contrast xenografts of Ad-GSCs expressed a Mesenchymal gene signature. Adherent GSC-derived xenografts had high STAT3 and ANGPTL4 expression, and enrichment for stem cell markers, transcriptional networks and pro-angiogenic markers characteristic of the Mesenchymal subtype. Examination of clinical samples from GBM patients showed that STAT3 expression was directly correlated with ANGPTL4 expression, and that increased expression of these genes correlated with poor patient survival and performance. A pharmacological STAT3 inhibitor abrogated STAT3 binding to the ANGPTL4 promoter and exhibited anticancer activity in vivo. Therefore, Ad-GSCs and Sp-GSCs produced histologically identical tumors with different gene expression patterns, and a STAT3/ANGPTL4 pathway is identified in glioblastoma that may serve as a target for therapeutic intervention. PMID:25955030

  17. Heterogeneity of HIV incidence: a comparative analysis between fishing communities and in a neighbouring rural general population, Uganda, and implications for HIV control

    PubMed Central

    Kamali, A; Nsubuga, R N; Ruzagira, E; Bahemuka, U; Asiki, G; Price, M A; Newton, R; Kaleebu, P; Fast, P

    2016-01-01

    Objectives To describe HIV heterogeneity in rural Uganda using incidence data collected between January 2012 and December 2014 among fishing cohort (FC) and in an adjacent rural general population cohort (GPC). Methods In the FC, eligible HIV high-risk adults aged 18+ years were enrolled, followed and HIV tested every 3 months. Demographic and sexual behaviour data were also collected. The GPC, approximately 47 km away from the FC, was followed through annual surveys, and sociodemographic and behavioural data collected. A subset of GPC with comparable risk profiles to the FC was selected. We presented sociodemographic and risk profiles and also computed stratified HIV incidence. Cox regression was used to assess factors associated with HIV incidence. Results Overall HIV incidence was higher in the FC than in the ‘high-risk’ GPC, 6.04 and 0.56 per 100 person years at risk, respectively, with a rate ratio (RR) of 10.83 (95% CI 6.11 to 19.76). This was higher among those aged 18–24 years, unmarried and those with more than two sex partners in the past year, RR of 15.44, 22.99 and 19.29, respectively. In the FC, factors associated with high incidence in multivariate analysis were duration in the community and unprotected sex. The factors in the GPC were ethnicity, marital status and duration in the community. Conclusions We have observed a substantial heterogeneity in HIV incidence. The high incidence in fishing communities is contributing greatly to the overall HIV burden in Uganda, and thus urgent combination prevention efforts are needed towards national goal to reduce HIV epidemic. PMID:26933046

  18. Heterogeneous pattern of selective pressure for PRRT2 in human populations, but no association with autism spectrum disorders.

    PubMed

    Huguet, Guillaume; Nava, Caroline; Lemière, Nathalie; Patin, Etienne; Laval, Guillaume; Ey, Elodie; Brice, Alexis; Leboyer, Marion; Szepetowski, Pierre; Gillberg, Christopher; Depienne, Christel; Delorme, Richard; Bourgeron, Thomas

    2014-01-01

    Inherited and de novo genomic imbalances at chromosome 16p11.2 are associated with autism spectrum disorders (ASD), but the causative genes remain unknown. Among the genes located in this region, PRRT2 codes for a member of the synaptic SNARE complex that allows the release of synaptic vesicles. PRRT2 is a candidate gene for ASD since homozygote mutations are associated with intellectual disability and heterozygote mutations cause benign infantile seizures, paroxysmal dyskinesia, or hemiplegic migraine. Here, we explored the contribution of PRRT2 mutations in ASD by screening its coding part in a large sample of 1578 individuals including 431 individuals with ASD, 186 controls and 961 individuals from the human genome Diversity Panel. We detected 24 nonsynonymous variants, 1 frameshift (A217PfsX8) and 1 in-frame deletion of 6 bp (p.A361_P362del). The frameshift mutation was observed in a control with no history of neurological or psychiatric disorders. The p.A361_P362del was observed in two individuals with autism from sub-Saharan African origin. Overall, the frequency of PRRT2 deleterious variants was not different between individuals with ASD and controls. Remarkably, PRRT2 displays a highly significant excess of nonsynonymous (pN) vs synonymous (pS) mutations in Asia (pN/pS = 4.85) and Europe (pN/pS = 1.62) compared with Africa (pN/pS = 0.26; Asia vs Africa: P = 0.000087; Europe vs Africa P = 0.00035; Europe vs Asia P = P = 0.084). We also showed that whole genome amplification performed through rolling cycle amplification could artificially introduce the A217PfsX8 mutation indicating that this technology should not be performed prior to PRRT2 mutation screening. In summary, our results do not support a role for PRRT2 coding sequence variants in ASD, but provide an ascertainment of its genetic variability in worldwide populations that should help researchers and clinicians to better investigate the role of PRRT2 in human diseases

  19. Heterogeneous Pattern of Selective Pressure for PRRT2 in Human Populations, but No Association with Autism Spectrum Disorders

    PubMed Central

    Huguet, Guillaume; Nava, Caroline; Lemière, Nathalie; Patin, Etienne; Laval, Guillaume; Ey, Elodie; Brice, Alexis; Leboyer, Marion; Szepetowski, Pierre; Gillberg, Christopher; Depienne, Christel; Delorme, Richard; Bourgeron, Thomas

    2014-01-01

    Inherited and de novo genomic imbalances at chromosome 16p11.2 are associated with autism spectrum disorders (ASD), but the causative genes remain unknown. Among the genes located in this region, PRRT2 codes for a member of the synaptic SNARE complex that allows the release of synaptic vesicles. PRRT2 is a candidate gene for ASD since homozygote mutations are associated with intellectual disability and heterozygote mutations cause benign infantile seizures, paroxysmal dyskinesia, or hemiplegic migraine. Here, we explored the contribution of PRRT2 mutations in ASD by screening its coding part in a large sample of 1578 individuals including 431 individuals with ASD, 186 controls and 961 individuals from the human genome Diversity Panel. We detected 24 nonsynonymous variants, 1 frameshift (A217PfsX8) and 1 in-frame deletion of 6 bp (p.A361_P362del). The frameshift mutation was observed in a control with no history of neurological or psychiatric disorders. The p.A361_P362del was observed in two individuals with autism from sub-Saharan African origin. Overall, the frequency of PRRT2 deleterious variants was not different between individuals with ASD and controls. Remarkably, PRRT2 displays a highly significant excess of nonsynonymous (pN) vs synonymous (pS) mutations in Asia (pN/pS = 4.85) and Europe (pN/pS = 1.62) compared with Africa (pN/pS = 0.26; Asia vs Africa: P = 0.000087; Europe vs Africa P = 0.00035; Europe vs Asia P = P = 0.084). We also showed that whole genome amplification performed through rolling cycle amplification could artificially introduce the A217PfsX8 mutation indicating that this technology should not be performed prior to PRRT2 mutation screening. In summary, our results do not support a role for PRRT2 coding sequence variants in ASD, but provide an ascertainment of its genetic variability in worldwide populations that should help researchers and clinicians to better investigate the role of PRRT2 in human diseases

  20. Predictors of Sexual Bother in a Population of Male North American Medical Students

    PubMed Central

    Smith, James F.; Breyer, Benjamin N.; Shindel, Alan W.

    2013-01-01

    Introduction The prevalence and associations of sexual bother in male medical students has not been extensively studied. Aims The aim of this study is to analyze predictors of sexual bother in a survey of male North American medical students. Methods Students enrolled in allopathic and osteopathic medical schools in North America between February 2008 and July 2008 were invited to participate in an internet-based survey of sexuality and sexual function. Main Outcome Measures The principle outcome measure was a single-item question inquiring about global satisfaction with sexual function. The survey also consisted of a questionnaire that included ethnodemographic factors, student status, sexual history, and a validated scale for the assessment of depression. Respondents completed the International Index of Erectile Function, the premature ejaculation diagnostic tool, and the Self-Esteem and Relationship Quality survey (SEAR). Descriptive statistics, analysis of variance, and multivariable logistic regression were utilized to analyze responses. Results There were 480 male subjects (mean age 26.3 years) with data sufficient for analysis. Forty-three (9%) reported sexual bother. Sexual bother was significantly more common in men with erectile dysfunction (ED), high risk of premature ejaculation (HRPE), depressive symptoms, and lower sexual frequency. However, after multivariate analysis including SEAR scores, ED, and HRPE were no longer independently predictive of sexual bother. Higher scores for all domains of the SEAR were associated with lower odds of sexual bother. Conclusions ED and HRPE are associated with sexual bother in this young and presumably healthy population. However, after controlling for relationship factors neither ED nor HRPE independently predicted sexual bother. It is plausible to hypothesize that sexual dysfunction from organic causes is rare in this population and is seldom encountered outside of relationship perturbations. Attention to

  1. A strategy for teaching students concepts of population-based health care for older persons.

    PubMed

    Xakellis, George C; Robinson, Mark

    2003-08-01

    The authors present a strategy for organizing and teaching the concepts of population-based health care for patients over the age of 65. The key ingredients are a case study based on a representative sample of 5,000 Medicare recipients and a student guide containing the sample group's demographics, clinical characteristics, and utilization patterns. As part of the case study, three subgroups within the sample are described: the basically healthy 50% that consume only 3% of medical resources, the most severely ill 10% that consume 70% of medical resources, and the moderately ill 40% that consume the remaining 27% of medical resources. These categories introduce the concepts of severity of illness, highlight the clinical challenges facing providers of care to the elderly, and contrast the divergent needs of individual health care consumers in an aging population. Armed with this succinct and manageable information packet, students are asked to play the role of an interdisciplinary team that is responsible for effectively managing the care of this population of 5,000 lives. Included in this article is a description of learning resources provided; sample group discussion questions; one strategy for caring for the population developed by a faculty-student group; and a brief description of the educational implications of the model. At the end of the article the reader is provided a Web address containing a description of the case and supporting materials (http://healthyaging.ucdavis.edu/education/continuing/ManagedMedicareTeachingCase.pdf). Readers are invited to view, print, and/or utilize the case in their own academic settings. PMID:12915368

  2. [Dietary, oral hygienic habits, dental surgeon attendance, and social background in police student's population].

    PubMed

    Faragó, Ildikó; Márton, Sándor; Túry, Ferenc; Bagi, István; Madléna, Melinda

    2009-02-01

    The aim of the study was to survey the dietary, oral hygienic habits, dental surgeon attendance and their relations with each other and social background in the Police School of Miskolc, Hungary. In this study, based on a questionnaire, 792 students [(mean age: 20.43 +/- 1.25 ys (mean +/- S.D.)] participated. Statistical analysis was performed using SPSS for Windows 10.0 statistical software. The daily consumption of sweets was 30.8%. There was no significant difference between educational level of father and frequency of consumption of sweets. The frequency of consumption of sweets significantly decreased with increasing the number of siblings (p < 0.05). The daily consumption of soft drinks was 28.8%. In the examined population 10% of the students used dental floss, most of them (60.0%) cleaned their teeth twice a day. Frequency of tooth-cleaning was significantly increased parallel to increase the educational level of father (p<0.05). Dental surgeon attendance aimed check up was 28.4% beside the compulsory yearly visit. The "3-times-tooth-cleaning" students visited their dentists within last 12 months in significantly higher percent than those of without daily tooth-cleaning (p < 0.05). There is a need to improve those factors which can affect oral health in the examined population. PMID:19402311

  3. Can Welfare Mothers Hack It in College? A Comparison of Achievement between TANF Recipients and General Population Community College Students

    ERIC Educational Resources Information Center

    Fenster, Judy

    2004-01-01

    The achievement of a group of undergraduate students enrolled in a pilot program for welfare recipients in the form of TANF (Temporary Aid to Needy Families) was compared with the achievement of general population students at an urban community college. Grades attained in a basic level, introductory Psychology course were used to measure academic…

  4. Culturally Diverse and Underserved Populations of Gifted Students in the United States and in Taiwan: Equitable Access to Gifted Education

    ERIC Educational Resources Information Center

    Ho, Ya-Ting

    2014-01-01

    There is a continuing increase in the African American and Hispanic student populations in public schools. The students who are invited to gifted programs are overwhelmingly White. This is the situation in schools in the United States and also in Taiwan. Misunderstanding or unawareness of culture difference among educators might contribute to…

  5. The Values and Attitudes of Selected College Students on Some Topics Relevant to Human Population. Monograph No. 31.

    ERIC Educational Resources Information Center

    Carballo, Jose Luis O.; And Others

    Results of a study on attitudes of Filipino college students concerning human population issues are reported. A total of 74 University of the Philippines students, half of whom were enrolled in a natural science course, answered a 15-part questionnaire on dating, friendship, premarital sex, marital expectations, and birth control. Several…

  6. Bifurcated Commitment, Priorities, and Social Contagion: The Dynamics and Correlates of Volunteering within a University Student Population

    ERIC Educational Resources Information Center

    Hustinx, Lesley; Vanhove, Tim; Declercq, Anja; Hermans, Koen; Lammertyn, Frans

    2005-01-01

    In spite of a progressive institutionalisation of community-based learning into higher education, relatively little is known about the actual dynamics and correlates of volunteering by students. The study presented seeks a more in-depth understanding of the spontaneous, extracurricular involvement within a university student population. Data are…

  7. Nursing Student Birth Doulas' Influence On the Childbearing Outcomes of Vulnerable Populations.

    PubMed

    Van Zandt, Shirley E; Kim, Soohyun; Erickson, Amanda

    2016-01-01

    Of 1,511 women served by nursing student birth doulas (Birth Companions) between 1998 and 2014, 34.5% were identified as vulnerable (refugees, non-English speakers, teens, low income, low education). This retrospective evaluation of the Birth Companions Program showed that vulnerable mothers had more epidurals and smaller babies, and attempted breastfeeding less frequently than nonvulnerable. There was no difference in the frequency of caesarean births, pitocin induction/augmentation, low birth weight, or preterm newborns among the vulnerable women. Birth Companion interventions may have a role in influencing these outcomes. The Birth Companions program will use this analysis to identify additional services for these populations. PMID:27383776

  8. Determination of ethyl glucuronide in hair to assess excessive alcohol consumption in a student population.

    PubMed

    Oppolzer, David; Barroso, Mário; Gallardo, Eugenia

    2016-03-01

    Hair analysis for ethyl glucuronide (EtG) was used to evaluate the pattern of alcohol consumption amongst the Portuguese university student population. A total of 975 samples were analysed. For data interpretation, the 2014 guidelines from the Society of Hair Testing (SoHT) for the use of alcohol markers in hair for the assessment of both abstinence and chronic excessive alcohol consumption were considered. EtG concentrations were significantly higher in the male population. The effect of hair products and cosmetics was evaluated by analysis of variance (ANOVA), and significant lower concentrations were obtained when conditioner or hair mask was used or when hair was dyed. Based on the analytical data and information obtained in the questionnaires from the participants, receiver operating characteristic (ROC) curves were constructed in order to determine the ideal cut-offs for our study population. Optimal cut-off values were estimated at 7.3 pg/mg for abstinence or rare occasional drinking control and 29.8 pg/mg for excessive consumption. These values are very close to the values suggested by the SoHT, proving their adequacy to the studied population. Overall, the obtained EtG concentrations demonstrate that participants are usually well aware of their consumption pattern, correlating with the self-reported consumed alcohol quantity, consumption habits and excessive consumption close to the time of hair sampling. PMID:26537927

  9. Projecting Enrollments for Delta College: Explosive Population Growth Will Enlarge and Diversify Delta's Student Body. Research Report.

    ERIC Educational Resources Information Center

    Evans, John W.

    In 1990, a study was conducted at California's San Joaquin Delta Community College (SJDCC) to examine student enrollment trends and to analyze alternative population projections. The purpose of the study was to prepare SJDCC for the fiscal, managerial, and educational challenges which the growing, ethnically diverse population would bring.…

  10. Medical students' attitudes toward underserved populations: changing associations with choice of primary care versus non-primary care residency.

    PubMed

    Wayne, Sharon; Timm, Craig; Serna, Lisa; Solan, Brian; Kalishman, Summers

    2010-05-01

    The number of medical students entering primary care residencies continues to decrease. The association between student attitudes toward underserved populations and residency choice has received little attention even though primary care physicians see a larger proportion of underserved patients than most other specialists. We evaluated attitudes toward underserved populations in 826 medical students using a standardized survey, and used logistic regression to assess the effect of attitudes, along with other variables, on selection of a primary care residency. We compared results between two groups defined by year of entry to medical school (1993-99 and 2000-05) to determine whether associations differed by time period. Students' attitudes regarding professional responsibility toward underserved populations remained high over the study period; however, there was a statistically. significant association between positive attitudes and primary care residency in the early cohort only. This association was not found in the more recent group. PMID:20453348

  11. Chlamydia Trachomitis Antigen in the Cervix: Prevalence in a Student Population

    PubMed Central

    Noble, Michael A.; Barteluk, Robin L.; Farquhar, Donald J.; Smith, Robin Percival

    1988-01-01

    The prevalence of chlamydia trachomatis was investigated over a two-year period in a population of women university students attending a student health clinic for routine pelvic examination or for a gynecologic complaint. Direct immunofluorescence slide test was used to determine the presence of C. trachomatis. The overall prevalence rates for the two-years periods studied were 8.2% and 7.1%. When women who had symptoms of a urogenital infection were compared to women who were asymptomatic, it was found that symptomatic women were more likely to have C. trachomatis in the cervix. To determine whether women with positive cases showed differences in appearance of the cervix, method of contraception, or other organisms colonizing the vagina, the cases were matched with two controls, and a retrospective chart review was performed. The cases were more likely to have cervicitis and to be culture positive with gardnerella vaginalis, and they were less likely to have used condoms for contraception. In the two periods studied, the carriage rates for asymptomatic cases were 6% and 5%. Fifty-eight per cent of all positive cases were asymptomatic. If this organism is to be eradicated from college-women populations, all women attending for a urogenital infection should be screened, and women attending for routine annual examinations should be screened if there is a clinical indication. PMID:21253068

  12. Noncognitive Predictors of Academic Performance and Persistence in Horizontal and Vertical Transfer Students by Academic Level

    ERIC Educational Resources Information Center

    Davis, Christopher A.

    2010-01-01

    College students increasingly are transferring among institutions of higher education in pursuit of their educational goals. The existing research on transfer students, however, does not adequately explore the unique characteristics of this heterogeneous population. The literature on transfer students suggests that transfer students are at-risk…

  13. Dental students' regard for patients from often-stigmatized populations: findings from an Indian dental school.

    PubMed

    Madhan, Balasubramanian; Gayathri, Haritheertham; Garhnayak, Lokanath; Naik, Eslavath Seena

    2012-02-01

    The aim of this study was to evaluate and compare a group of Indian dental students' attitudes toward HIV-positive status, substance misuse, intellectual disability, acute mental illness, and lesbian, gay, bisexual, transgender (LGBT) orientation. Two hundred and twelve students at various stages in the dental curriculum anonymously completed the Medical Condition Regard Scale (MCRS) for these conditions. Friedman and Kruskal-Wallis tests were used, respectively, to analyze the intrastage and interstage differences in MCRS scores. The results revealed that the regard of dental students was considerably positive for all the conditions except LGBT, for which it was just borderline positive. Intellectual disability received the highest regard among all the conditions and LGBT the least. An intermediary and comparable regard was noted for acute mental illness and HIV-positive status followed by substance misuse. While the regard for LGBT remained consistent throughout the curriculum, those for other conditions showed a marginal decrease at the completion of the clinical training. Active curricular reforms are required to ensure a more inclusive and nondiscriminatory dental care environment for patients from such often-stigmatized populations, especially those with LGBT orientation and substance misuse. PMID:22319086

  14. Variance associated with subject velocity and trial repetition during force platform gait analysis in a heterogeneous population of clinically normal dogs

    PubMed Central

    Hans, Eric C.; Zwarthoed, Berdien; Seliski, Joseph; Nemke, Brett; Muir, Peter

    2016-01-01

    Factors that contribute to variance in ground reaction forces (GRF) include: dog morphology, velocity, and trial repetition. Narrow velocity ranges are recommended to minimize variance. In a heterogeneous population of clinically normal dogs, we hypothesized that the dog subject effect would account for the majority of variance in peak vertical force (PVF) and vertical impulse (VI) at a trotting gait, and that narrow velocity ranges would be associated with less variance. Data from twenty normal dogs were obtained. Each dog was trotted across a force platform at its habitual velocity, with controlled acceleration (±0.5m/s2). Variance effects from twelve trotting velocity ranges were examined using repeated-measures analysis-of-covariance. Significance was set at P<0.05. Mean dog body weight was 28.4 ± 7.4 kg. Individual dog and velocity significantly affected PVF and VI for thoracic and pelvic limbs (P<0.001). Trial number significantly affected thoracic limb PVF (P<0.001). Limb (left or right) significantly affected thoracic limb VI (P=0.02). The magnitude of variance effects from largest to smallest was dog, velocity, trial repetition, and limb. Velocity ranges of 1.5–2.0 m/s, 1.8–2.2 m/s, and 1.9–2.2 m/s were associated with low variance and no significant effects on thoracic or pelvic limb PVF and VI. A combination of these ranges, 1.5–2.2 m/s, captured a large percentage of trials per dog (84.2±21.4%) with no significant effects on thoracic or pelvic limb PVF or VI. We conclude wider velocity ranges facilitate capture of valid trials with little to no effect on GRF in normal trotting dogs. This concept is important for clinical trial design. PMID:25457264

  15. Antibody responses induced by Leish-Tec®, an A2-based vaccine for visceral leishmaniasis, in a heterogeneous canine population.

    PubMed

    Testasicca, Miriam C de Souza; dos Santos, Mariana Silva; Machado, Leopoldo Marques; Serufo, Angela Vieira; Doro, Daniel; Avelar, Daniel; Tibúrcio, Ana Maria Leonardi; Abrantes, Christiane de Freitas; Machado-Coelho, George Luiz Lins; Grimaldi, Gabriel; Gazzinelli, Ricardo Tostes; Fernandes, Ana Paula

    2014-08-29

    Zoonotic visceral leishmaniasis (VL) is a widespread disease, and dogs are the main reservoirs for human parasite transmission. Hence, development of an effective vaccine that prevents disease and reduces the transmission of VL is required. As euthanasia of seropositive dogs is recommended in Brazil for VL epidemiological control, to include anti-VL canine vaccines as a mass control measure it is necessary to characterize the humoral responses induced by vaccination and if they interfere with the reactivity of vaccinated dogs in serological diagnostic tests. Leish-Tec(®) is an amastigote-specific A2 recombinant protein vaccine against canine visceral leishmaniasis (CVL) that is commercially available in Brazil. Here, we tested the immunogenicity of Leish-Tec(®) in a heterogeneous dog population by measuring A2-specific antibody responses. Healthy dogs (n=140) of various breeds were allocated to two groups: one group received Leish-Tec(®) (n=70), and the other group received a placebo (n=70). Anti-A2 or anti-Leishmania promastigote antigen (LPA) antibody levels were measured by ELISA in serum samples collected before and after vaccination. An immunochromatographic test (DPP) based on the recombinant K28 antigen was also used for serodiagnosis of CVL. Vaccinated animals, except one, remained seronegative for anti-LPA total IgG and anti-K28 antibodies. Conversely, seropositivity for anti-A2 total IgG antibodies was found in 98% of animals after vaccination. This value decreased to 81.13% at 6 months before rising again (98%), after the vaccination boost. Anti-A2 IgG2 and IgG1 titers were also increased in vaccinated animals relative to control animals. These data indicate that Leish-Tec(®) is immunogenic for dogs of different genetic backgrounds and that humoral responses induced by vaccination can be detected by A2-ELISA, but do not interfere with the LPA-ELISA and DPP diagnostic tests for CVL. PMID:24863572

  16. Variance associated with subject velocity and trial repetition during force platform gait analysis in a heterogeneous population of clinically normal dogs.

    PubMed

    Hans, Eric C; Zwarthoed, Berdien; Seliski, Joseph; Nemke, Brett; Muir, Peter

    2014-12-01

    Factors that contribute to variance in ground reaction forces (GRF) include dog morphology, velocity, and trial repetition. Narrow velocity ranges are recommended to minimize variance. In a heterogeneous population of clinically normal dogs, it was hypothesized that the dog subject effect would account for the majority of variance in peak vertical force (PVF) and vertical impulse (VI) at a trotting gait, and that narrow velocity ranges would be associated with less variance. Data from 20 normal dogs were obtained. Each dog was trotted across a force platform at its habitual velocity, with controlled acceleration (±0.5 m/s(2)). Variance effects from 12 trotting velocity ranges were examined using repeated-measures analysis-of-covariance. Significance was set at P <0.05. Mean dog bodyweight was 28.4 ± 7.4 kg. Individual dog and velocity significantly affected PVF and VI for thoracic and pelvic limbs (P <0.001). Trial number significantly affected thoracic limb PVF (P <0.001). Limb (left or right) significantly affected thoracic limb VI (P = 0.02). The magnitude of variance effects from largest to smallest was dog, velocity, trial repetition, and limb. Velocity ranges of 1.5-2.0 m/s, 1.8-2.2 m/s, and 1.9-2.2 m/s were associated with low variance and no significant effects on thoracic or pelvic limb PVF and VI. A combination of these ranges, 1.5-2.2 m/s, captured a large percentage of trials per dog (84.2 ± 21.4%) with no significant effects on thoracic or pelvic limb PVF or VI. It was concluded that wider velocity ranges facilitate capture of valid trials with little to no effect on GRF in normal trotting dogs. This concept is important for clinical trial design. PMID:25457264

  17. Thyroid cancer GWAS identifies 10q26.12 and 6q14.1 as novel susceptibility loci and reveals genetic heterogeneity among populations.

    PubMed

    Mancikova, Veronika; Cruz, Raquel; Inglada-Pérez, Lucía; Fernández-Rozadilla, Ceres; Landa, Iñigo; Cameselle-Teijeiro, José; Celeiro, Catuxa; Pastor, Susana; Velázquez, Antonia; Marcos, Ricard; Andía, Victor; Álvarez-Escolá, Cristina; Meoro, Amparo; Schiavi, Francesca; Opocher, Giuseppe; Quintela, Inés; Ansede-Bermejo, Juan; Ruiz-Ponte, Clara; Santisteban, Pilar; Robledo, Mercedes; Carracedo, Angel

    2015-10-15

    Thyroid cancer is the most heritable cancer of all those not displaying typical Mendelian inheritance. However, most of the genetic factors that would explain the high heritability remain unknown. Our aim was to identify additional common genetic variants associated with susceptibility to this disease. In order to do so, we performed a genome-wide association study in a series of 398 cases and 502 controls from Spain, followed by a replication in four well-defined Southern European case-control collections contributing a total of 1,422 cases and 1,908 controls. The association between the variation at the 9q22 locus near FOXE1 and thyroid cancer risk was consistent across all series, with several SNPs identified (rs7028661: OR = 1.64, p = 1.0 × 10(-22) , rs7037324: OR = 1.54, p = 1.2 × 10(-17) ). Moreover, the rare alleles of three SNPs (rs2997312, rs10788123 and rs1254167) at 10q26.12 showed suggestive evidence of association with higher risk of the disease (OR = 1.35, p = 1.2 × 10(-04) , OR = 1.26, p = 5.2 × 10(-04) and OR = 1.38, p = 5.9 × 10(-05) , respectively). Finally, the rare allele of rs4075570 at 6q14.1 conferred protection in the series studied (OR = 0.82, p = 2.0 × 10(-04) ). This study suggests that heterogeneity in genetic susceptibility between populations is a key feature to take into account when exploring genetic risk factors related to this disease. PMID:25855579

  18. An Untapped Resource for Increasing College Attainment: Estimating the Population of Potential First-Generation Students in Wisconsin. WISCAPE Policy Brief

    ERIC Educational Resources Information Center

    Lazenby, Sara

    2011-01-01

    Potential first-generation students make up a large segment of Wisconsin's teenage population. To increase the pool of educated workers in Wisconsin, policymakers must work to recruit, retain, and graduate these students. Estimates of the size of the first-generation student population in the state are crucial for these efforts. This brief…

  19. Transition and Students with Twice Exceptionality

    ERIC Educational Resources Information Center

    Prior, Susan

    2013-01-01

    "Twice exceptional" is one of the terms used to describe students who have giftedness and a disability. This is a small heterogeneous population of individual learners who are underserved in special, gifted, and mainstream education settings. Despite the availability of research on transition for students with disabilities, there is…

  20. Training Students to Analyze Spatial and Temporal Heterogeneities in Reservoir and Seal Petrology, Mineralogy, and Geochemistry: Implications for CO{sub 2} Sequestration Prediction, Simulation, and Monitoring

    SciTech Connect

    Bowen, Brenda

    2013-09-30

    The objective of this project was to expose and train multiple students in geological tools that are essential to reservoir characterization and geologic sequestration including but not limited to advanced petrological methods, mineralogical methods, and geochemical methods; core analysis, and geophysical well-log interpretation. These efforts have included training of multiple students through geologically based curriculum and research using advanced petrological, mineralogical, and geochemical methods. In whole, over the last 3+ years, this award has supported 5,828 hours of student research, supporting the work of several graduate and undergraduate students. They have all received training directly related to ongoing CO{sub 2} sequestration demonstrations. The students have all conducted original scientific research on topics related to understanding the importance of lithological, textural, and compositional variability in formations that are being targeted as CO{sub 2} sequestration reservoirs and seals. This research was linked to the Mount Simon Sandstone reservoir and overlying Eau Claire Formation seal in the Illinois Basin- a system where over one million tons of CO{sub 2} are actively being injected with the first large-scale demonstration of anthropogenic CO{sub 2} storage in the U.S. Student projects focused specifically on 1) reservoir porosity characterization and evaluation, 2) petrographic, mineralogical, and geochemical evidence of fluid-related diagenesis in the caprock, 3) textural changes in reservoir samples exposed to experimental CO{sub 2} + brine conditions, 4) controls on spatial heterogeneity in composition and texture in both the reservoir and seal, 5) the implications of small-scale fractures within the reservoir, and 6) petrographic and stable isotope analyses of carbonates in the seal to understand the burial history of the system. The student-led research associated with this project provided real-time and hands-on experience with a

  1. Language Shift and the Inclusion of Indigenous Populations in Large-Scale Assessment Programs

    ERIC Educational Resources Information Center

    Solano-Flores, Guillermo; Backhoff, Eduardo; Contreras-Niño, Luis A.; Vázquez-Muñoz, Mariana

    2015-01-01

    Indicators of academic achievement for bilingual students can be inaccurate due to linguistic heterogeneity. For indigenous populations, language shift (the gradual replacement of one language by another) is a factor that can increase this heterogeneity and poses an additional challenge for valid testing. We investigated whether and how indigenous…

  2. Political Jurisdictions in Heterogeneous Communities.

    ERIC Educational Resources Information Center

    Alesina, Alberto; Baqir, Reza; Hoxby, Caroline

    2004-01-01

    We investigate whether political jurisdictions form in response to the trade-off between economies of scale and the costs of a heterogeneous population. We consider heterogeneity in income, race, ethnicity, and religion, and we test the model using American school districts, school attendance areas, municipalities, and special districts. We find…

  3. Gambling and Attention Deficit Hyperactivity Disorders (ADHD) in a Population of French Students.

    PubMed

    Romo, L; Rémond, J J; Coeffec, A; Kotbagi, G; Plantey, S; Boz, F; Kern, L

    2015-12-01

    Attention deficit disorder with or without hyperactivity (ADD/ADHD) is a neurodevelopmental disorder that can be exacerbated by psychosocial factors. Various studies confirm that the severity of a psychiatric disorder, particularly when it comes to ADHD, is strongly correlated with the amount of use. This study (1) evaluated the association between ADHD and gambling among young students; (2) determined which symptom among ADHD's three symptoms (attention deficit, hyperactivity, or impulsivity) had the strongest association with video game addiction and gambling; and (3) determined the impact of the association between ADHD and video game addiction and gambling on self-esteem and academic performance of students. A total of 720 students (445 males and 274 females) were recruited from eight higher educational institutions of Ile de France. They all completed a battery of questionnaire consisting of Canadian Problem Gambling Index, UPPS Impulsive Behavior Scale, Wender Utah Rating Scale (WURS), Adult ADHD Self-Report Scale (ASRS) and Rosenberg scales, and socio-demographic data. 13.33% of the participants had symptoms of ADHD during childhood (WURS scale score) and 40.41% of them have symptoms of ADHD in adulthood (ASRS score). Finally, among the participants, 37.5% had excessive gambling addiction, have positive results on WURS and ASRS scales, thus having a probable ADHD, whereas 14.55% had no gambling addiction. The results demonstrated that adult ADHD was associated with gambling addiction. Significant associations were observed between ADHD and impulsivity, academic difficulties and gambling addiction. The association between ADHD and gambling seems to be common among vulnerable populations such as adolescents and could be related to variables such as self-esteem, which appears to potentially worsen the prognosis. Further research on this relationship is needed to optimize prevention strategies and effective treatment. PMID:25466366

  4. Estimate of dietary exposure to sulphites using Brazilian students as a sample population.

    PubMed

    Popolim, W D; De V C Penteado, M

    2005-11-01

    In Brazil, there is neither a register of the use of sulphites by the food industry nor is research being undertaken on their dietary exposure to the population. The objective of the work reported here was to estimate the dietary exposure to sulphites in two different groups of high school students, a fee-paying school group and a state school group. The data were collected through a 24-hour dietary recall, which provided estimates of sulphited foods and beverages in the diet. The Maximum Permitted Level (MPL), established by the Brazilian legislation for each of the sulphited food and beverages, was used to measure the dietary exposure to this additive. On this basis none of the students could have exceeded the Acceptable Daily Intake (ADI) of 0.70 mg SO2/kg bw/day, with a average dietary exposure of 0.07 mg SO2/kg bw/day (p<0.001), with no significant statistical difference (p=0.643) between fee-paying and state school students. Highly exposed consumers (dietary exposure to more than 50% of the ADI, or either, 0.35 mg SO2/kg bw/day, to the maximum of 0.52 mg SO2/kg bw/dia) represented 4.5% of the researched samples and reached these levels of intake due to a consumption beyond 500 ml/day of industrialized packaged fruit juices, and, in the fee-paying school, for associating its consumption with alcoholic beverages like beer and wine. PMID:16332633

  5. Rightward dominance in temporal high-frequency electrical asymmetry corresponds to higher resting heart rate and lower baroreflex sensitivity in a heterogeneous population

    PubMed Central

    Tegeler, Charles H; Shaltout, Hossam A; Tegeler, Catherine L; Gerdes, Lee; Lee, Sung W

    2015-01-01

    Objective Explore potential use of a temporal lobe electrical asymmetry score to discriminate between sympathetic and parasympathetic tendencies in autonomic cardiovascular regulation. Methods 131 individuals (82 women, mean age 43.1, range 13–83) with diverse clinical conditions completed inventories for depressive (CES-D or BDI-II) and insomnia-related (ISI) symptomatology, and underwent five-minute recordings of heart rate and blood pressure, allowing calculation of heart rate variability and baroreflex sensitivity (BRS), followed by one-minute, two-channel, eyes-closed scalp recordings of brain electrical activity. A temporal lobe high-frequency (23–36 Hz) electrical asymmetry score was calculated for each subject by subtracting the average amplitude in the left temporal region from amplitude in the right temporal region, and dividing by the lesser of the two. Results Depressive and insomnia-related symptomatology exceeding clinical threshold levels were reported by 48% and 50% of subjects, respectively. Using a cutoff value of 5% or greater to define temporal high-frequency asymmetry, subjects with leftward compared to rightward asymmetry were more likely to report use of a sedative-hypnotic medication (42% vs. 22%, P = 0.02). Among subjects with asymmetry of 5% or greater to 30% or greater, those with rightward compared to leftward temporal high-frequency asymmetry had higher resting heart rate (≥5% asymmetry, 72.3 vs. 63.8, P = 0.004; ≥10%, 71.5 vs. 63.0, P = 0.01; ≥20%, 72.2 vs. 64.2, P = 0.05; ≥30%, 71.4 vs. 64.6, P = 0.05). Subjects with larger degrees of rightward compared to leftward temporal high-frequency asymmetry had lower baroreflex sensitivity (≥40% asymmetry, 10.6 vs. 16.4, P = 0.03; ≥50% asymmetry, 10.4 vs. 16.7, P = 0.05). Conclusion In a heterogeneous population, individuals with rightward compared to leftward temporal high-frequency electrical asymmetry had higher resting heart rate and lower BRS. Two

  6. Occlusal dental caries incidence and implications for sealant programs in a US college student population.

    PubMed

    Stahl, J W; Katz, R V

    1993-01-01

    Given the decline in dental caries incidence in preteens and young teenagers in the United States, a study of the incidence of dental caries in young adults (17-23 years) was conducted to provide a descriptive epidemiologic picture of this "new" natural history of dental caries in the late and post-teenage years. A retrospective study was performed analyzing the detailed dental records of the four-year college experience in the class of 1989, US Coast Guard Academy. Occlusal caries incidence, in the absence of associated proximal caries, was shown to be moderately common in molars (11.9%) and rare in premolars (0.8%). In contrast to previous studies' findings, demographic indicators, socioeconomic status indicators, and prior caries experience were poor predictors of occlusal caries incidence; targeting a universal sealant policy in this population therefore would be done best by tooth type rather than patient type. A preliminary cost-comparison model, projected over a 40-month period, suggests that the cost of initiating a universal molar sealant policy in this population would be 92 cents per year per student greater than the cost of restoring occlusal caries in the presence of sound proximal surfaces. This cost comparison suggests that it would be advantageous to initiate such a policy. PMID:8258782

  7. An Intra Population Analysis of Migrant Student Performance Based on the Migrant Student Record Transfer System Data Base.

    ERIC Educational Resources Information Center

    Hackett, Eugene de G.; McManus, James V.

    Educational services data contained in the Migrant Student Record Transfer System (MSRTS) database were used to examine some effects of the migrant education program on student performance, and how student performance varied with the amount and duration of exposure to general and particular program components. Problems with using the MSRTS…

  8. Subjective Evaluations of Intelligence and Academic Self-Concept Predict Academic Achievement: Evidence from a Selective Student Population

    ERIC Educational Resources Information Center

    Kornilova, Tatiana V.; Kornilov, Sergey A.; Chumakova, Maria A.

    2009-01-01

    The study examined the relationship between implicit theories, goal orientations, subjective and test estimates of intelligence, academic self-concept, and achievement in a selective student population (N=300). There was no direct impact of implicit theories of intelligence and goal orientations on achievement. However, subjective evaluations of…

  9. The Dominance Concept Inventory: A Tool for Assessing Undergraduate Student Alternative Conceptions about Dominance in Mendelian and Population Genetics

    ERIC Educational Resources Information Center

    Abraham, Joel K.; Perez, Kathryn E.; Price, Rebecca M.

    2014-01-01

    Despite the impact of genetics on daily life, biology undergraduates understand some key genetics concepts poorly. One concept requiring attention is dominance, which many students understand as a fixed property of an allele or trait and regularly conflate with frequency in a population or selective advantage. We present the Dominance Concept…

  10. Exploring Dual Credit Data Alignment, Student Populations, and Coursework Patterns in Texas Using a P-16 Framework

    ERIC Educational Resources Information Center

    Eklund, Julie Ann

    2009-01-01

    This multi-faceted study of dual credit programs in Texas was motivated by perceived discrepancies in dual credit data reporting and a lack of comprehensive, state-level information about dual credit student populations and coursework patterns. Using a P-16 framework, the author explored alignment issues that influence the delivery of dual credit…

  11. Process-Oriented Guided-Inquiry Learning in an Introductory Anatomy and Physiology Course with a Diverse Student Population

    ERIC Educational Resources Information Center

    Brown, Patrick J. P.

    2010-01-01

    Process-oriented guided-inquiry learning (POGIL), a pedagogical technique initially developed for college chemistry courses, has been implemented for 2 yr in a freshman-level anatomy and physiology course at a small private college. The course is populated with students with backgrounds ranging from no previous college-level science to junior and…

  12. The Population Reference Bureau's Population Handbook. A Quick Guide to Population Dynamics for Journalists, Policymakers, Teachers, Students, and Other People Interested in People. Second Edition.

    ERIC Educational Resources Information Center

    Haupt, Arthur; Kane, Thomas T.

    Demography is the scientific study of populations. Population change has an impact on every facet of life. This revised handbook contains additional information on how to calculate the total fertility rate and life tables. The purpose of the handbook is to clarify and explain demographic terminology, to aid public understanding, and to assist…

  13. Preparing for Patient-Centered Care: Assessing Nursing Student Knowledge, Comfort, and Cultural Competence Toward the Latino Population

    PubMed Central

    Mayo, Rachel M.; Sherrill, Windsor W.; Truong, Khoa D.; Nichols, Christina M.

    2016-01-01

    As the Latino population continues to grow throughout the United States, cultural competence training of nursing students at the baccalaureate level has become a priority. This study aimed to explore undergraduate nursing students’ attitudes and beliefs toward Latino patients and their perceived readiness to provide care to Latino patients. A cross-sectional survey was conducted at four major nursing schools in the southeastern United States, which is the region that has seen the highest percentage of growth in the Latino population. Results from multivariable regression suggest that social interaction with Latino individuals and cultural immersion in a Spanish-speaking country predict student knowledge, cultural competence, and comfort with Latino patients. Direct influence by nursing programs, such as clinical experience, coursework, and language proficiency, are positively associated with the designed outcomes, but these relationships are not statistically significant. Our findings suggest that dosage of training matters. Implications for student recruitment, selection, and training are discussed. PMID:24766083

  14. Dynamic heterogeneity of DNA methylation and hydroxymethylation in embryonic stem cell populations captured by single-cell 3D high-content analysis

    SciTech Connect

    Tajbakhsh, Jian; Stefanovski, Darko; Tang, George; Wawrowsky, Kolja; Liu, Naiyou; Fair, Jeffrey H.

    2015-03-15

    Cell-surface markers and transcription factors are being used in the assessment of stem cell fate and therapeutic safety, but display significant variability in stem cell cultures. We assessed nuclear patterns of 5-hydroxymethylcytosine (5hmC, associated with pluripotency), a second important epigenetic mark, and its combination with 5-methylcytosine (5mC, associated with differentiation), also in comparison to more established markers of pluripotency (Oct-4) and endodermal differentiation (FoxA2, Sox17) in mouse embryonic stem cells (mESC) over a 10-day differentiation course in vitro: by means of confocal and super-resolution imaging together with 3D high-content analysis, an essential tool in single-cell screening. In summary: 1) We did not measure any significant correlation of putative markers with global 5mC or 5hmC. 2) While average Oct-4 levels stagnated on a cell-population base (0.015 lnIU/day), Sox17 and FoxA2 increased 22-fold and 3-fold faster, respectively (Sox17: 0.343 lnIU/day; FoxA2: 0.046 lnIU/day). In comparison, global DNA methylation levels increased 4-fold faster (0.068 lnIU/day), and global hydroxymethylation declined at 0.046 lnIU/day, both with a better explanation of the temporal profile. 3) This progression was concomitant with the occurrence of distinct nuclear codistribution patterns that represented a heterogeneous spectrum of states in differentiation; converging to three major coexisting 5mC/5hmC phenotypes by day 10: 5hmC{sup +}/5mC{sup −}, 5hmC{sup +}/5mC{sup +}, and 5hmC{sup −}/5mC{sup +} cells. 4) Using optical nanoscopy we could delineate the respective topologies of 5mC/5hmC colocalization in subregions of nuclear DNA: in the majority of 5hmC{sup +}/5mC{sup +} cells 5hmC and 5mC predominantly occupied mutually exclusive territories resembling euchromatic and heterochromatic regions, respectively. Simultaneously, in a smaller subset of cells we observed a tighter colocalization of the two cytosine variants, presumably

  15. Dynamic Heterogeneity of DNA Methylation and Hydroxymethylation in Embryonic Stem Cell Populations Captured by Single-Cell 3D High-Content Analysis

    PubMed Central

    Tajbakhsh, Jian; Stefanovski, Darko; Tang, George; Wawrowsky, Kolja; Liu, Naiyou; Fair, Jeffrey H.

    2015-01-01

    Cell-surface markers and transcription factors are being used in the assessment of stem cell fate and therapeutic safety, but display significant variability in stem cell cultures. We assessed nuclear patterns of 5-hydroxymethylcytosine (5hmC, associated with pluripotency), a second important epigenetic mark, and its combination with 5-methylcytosine (5mC, associated with differentiation), also in comparison to more established markers of pluripotency (Oct-4) and endodermal differentiation (FoxA2, Sox17) in mouse embryonic stem cells (mESC) over a ten-day differentiation course in vitro: by means of confocal and super-resolution imaging together with high-content analysis, an essential tool in single-cell screening. In summary: 1) We did not measure any significant correlation of putative markers with global 5mC or 5hmC. 2) While average Oct-4 levels stagnated on a cell-population base (0.015 lnIU per day), Sox17 and FoxA2 increased 22-fold and 3-fold faster, respectively (Sox17:0.343 lnIU/day; FoxA2: 0.046 lnIU/day). In comparison, DNA global methylation levels increased 4-fold faster (0.068 lnIU/day), and global hydroxymethylation declined at 0.046 lnIU/day, both with a better explanation of the temporal profile. 3) This progression was concomitant with the occurrence of distinct nuclear codistribution patterns that represented a heterogeneous spectrum of states in differentiation; converging to three major coexisting 5mC/5hmC phenotypes by day 10: 5hmC+/5mC−, 5hmC+/5mC+, and 5hmC−/5mC+ cells. 4) Using optical nanoscopy we could delineate the respective topologies of 5mC/5hmC colocalization in subregions of nuclear DNA: in the majority of 5hmC+/5mC+ cells 5hmC and 5mC predominantly occupied mutually exclusive territories resembling euchromatic and heterochromatic regions, respectively. Simultaneously, in a smaller subset of cells we observed a tighter colocalization of the two cytosine variants, presumably delineating chromatin domains in remodeling. We

  16. Changes of heterogeneous cell populations in the Ishikawa cell line during long-term culture: Proposal for an in vitro clonal evolution model of tumor cells.

    PubMed

    Kasai, Fumio; Hirayama, Noriko; Ozawa, Midori; Iemura, Masashi; Kohara, Arihiro

    2016-06-01

    Genomic changes in tumor cell lines can occur during culture, leading to differences between cell lines carrying the same name. In this study, genome profiles between low and high passages were investigated in the Ishikawa 3-H-12 cell line (JCRB1505). Cells contained between 43 and 46 chromosomes and the modal number changed from 46 to 45 during culture. Cytogenetic analysis revealed that a translocation t(9;14), observed in all metaphases, is a robust marker for this cell line. Single-nucleotide polymorphism microarrays showed a heterogeneous copy number in the early passages and distinct profiles at late passages. These results demonstrate that cell culture can lead to elimination of ancestral clones by sequential selection, resulting in extensive replacement with a novel clone. Our observations on Ishikawa cells in vitro are different from the in vivo heterogeneity in which ancestral clones are often retained during tumor evolution and suggest a model for in vitro clonal evolution. PMID:27107655

  17. Demographics of undergraduates studying games in the United States: a comparison of computer science students and the general population

    NASA Astrophysics Data System (ADS)

    McGill, Monica M.; Settle, Amber; Decker, Adrienne

    2013-06-01

    Our study gathered data to serve as a benchmark of demographics of undergraduate students in game degree programs. Due to the high number of programs that are cross-disciplinary with computer science programs or that are housed in computer science departments, the data is presented in comparison to data from computing students (where available) and the US population. Participants included students studying games at four nationally recognized postsecondary institutions. The results of the study indicate that there is no significant difference between the ratio of men to women studying in computing programs or in game degree programs, with women being severely underrepresented in both. Women, blacks, Hispanics/Latinos, and heterosexuals are underrepresented compared to the US population. Those with moderate and conservative political views and with religious affiliations are underrepresented in the game student population. Participants agree that workforce diversity is important and that their programs are adequately diverse, but only one-half of the participants indicated that diversity has been discussed in any of their courses.

  18. Teacher's Understanding, Perceptions, and Experiences of Students in Foster Care: A Forgotten Population

    ERIC Educational Resources Information Center

    Watson-Davis, Darneika

    2010-01-01

    The purpose of this study is to examine elementary teacher's understanding, perceptions, and experiences of working with students in foster care. The researcher examined whether teachers are informed about students in foster care, determined teacher's understanding of the foster care system, and how their students are affected. The results…

  19. Student Involvement in Learning Action Packet. Research, Strategies and Programs for Special Populations.

    ERIC Educational Resources Information Center

    Research for Better Schools, Inc., Philadelphia, PA.

    To improve the responsiveness of educational programs to the needs of low achieving, at risk students, Research for Better Schools (RBS) has developed an assessment procedure. This document is the portion of that procedure that addresses the involvement of students in their learning, or how low achieving students cognitively operate on content.…

  20. Factors Affecting the Graduation Rates of University Students from Underrepresented Populations

    ERIC Educational Resources Information Center

    Creighton, Linda M.

    2007-01-01

    One of the most pressing issues facing American universities is the number of students who fail to graduate. Nearly one out of five four-year institutions graduate fewer than one-third of its first-time, full-time degree-seeking first-year students within six years. Although there are various explanations for attrition, students often leave for…

  1. The Impact of an Economically Disadvantaged Student Population on School Climate

    ERIC Educational Resources Information Center

    Null, Curtis F.

    2012-01-01

    The purpose of this study was to determine the relationship between student poverty levels, defined by the number of students identified as economically disadvantaged by qualifying for free and reduced lunch and school climate. The literature review examined school climate and culture, effects of student socioeconomic (SES) status on education,…

  2. The Unique Leadership Needs of Minority Student Populations: Crafting a Leadership Identity

    ERIC Educational Resources Information Center

    Baughman, Kristen N.; Bruce, Jacklyn

    2011-01-01

    The purpose of this qualitative study was to determine how college-level minority student leaders make meaning of those leadership experiences. Semi-structured interviews were conducted with 12 students. Major findings noted a strong personal motivation to participate in student leadership positions. Further research on the impact of familial…

  3. Pluralistic Ignorance among Student-Athlete Populations: A Factor in Academic Underperformance

    ERIC Educational Resources Information Center

    Levine, Joshua; Etchison, Sara; Oppenheimer, Daniel M.

    2014-01-01

    It is well documented that student-athletes underperform academically. Some researchers have suggested that this underperformance is because student-athletes lack motivation in academic endeavors. In contrast, we find that most student-athletes hold positive private attitudes towards academic achievement, but also believe that their peers do not.…

  4. Raising the Question #9: Is the Student-Athlete Population Unique? and Why Should We Care?

    ERIC Educational Resources Information Center

    Jolly, J. Christopher

    2008-01-01

    There are unique aspects of the student-athlete collegiate experience that create substantial challenges for student-athletes' academic success. Athletic culture, extreme time demands on student-athletes, and the often uneasy marriage between athletics and academics in the university setting all contribute to the difficulties that many…

  5. A pilot investigation of "metaphor blindness" in a college student population.

    PubMed

    Jalal, Baland; Ramachandran, Vilayanur S

    2014-06-01

    Previous research from our group suggests that patients with lesions in the left inferior parietal lobule (IPL)-which is concerned with abstract numerical cognition and cross-modal association (which is consistent with its strategic location at the crossroads between the temporal, parietal and occipital lobes) have difficulty understanding proverbs and metaphors (Ramachandran and Hubbard, 2001). In the current pilot investigation, we report "metaphor blindness" in a college student population; that is, either the complete inability or difficulty for otherwise intellectually non-challenged individuals to comprehend metaphors of language. Participants (N=205) read 12 metaphorical ("The detective jumped at the clue") and 12 literal ("The accident was a fall") sentences and had to decide whether the sentences conveyed a metaphorical or literal meaning. The mean accuracy for these metaphorical sentences was 11.0 (SD=2.3; RNG=0-12); the mean accuracy for literal sentences was 7.2 (SD=1.8; RNG=2-10). We found that 5% of participants (11/205) were unable or had difficulty understanding metaphors (i.e., were statistical outliers), while their score for literal sentences felt within a normal statistical range M=8.3 (SD=2.3; RNG=5-10). Follow-up control procedures were conducted in order to help ascertain that the results were not due to low verbal IQ and task difficulty. Likewise, none of the "metaphor blind" participants reported any psychiatric or neurological histories that would impair language comprehension, including strokes, brain injuries, language problems dyslexia, and signs of late language onset. The results are very preliminary and future studies are needed to confirm these findings. We suggest that brain modules may be specialized even for subtle functions like metaphor and their formation in embryogenesis may be controlled by small handfuls of genes whose expression can go awry--as in "metaphor blindness". PMID:24661940

  6. Second International Mathematics Study; Longitudinal, Classroom Process Surveys for Population A: Students, Teachers, and Schools, 1981-1982 [machine-readable data file].

    ERIC Educational Resources Information Center

    Wolfe, Richard G.

    The Second International Mathematics Study (SIMS) of the International Association for the Evaluation of Educational Achievement (IEA) was conducted in 20 countries on two sampled populations: Population A of 13-year-olds and Population B of students studying mathematics in their final year of secondary school. Mathematics achievement was measured…

  7. Demographic Changes of Hispanic Populations and Hispanic Student Enrollment in Texas Community Colleges: A Literature Review

    ERIC Educational Resources Information Center

    Hernandez, Jack; Slate, John R.; Joyner, Sheila A.

    2015-01-01

    In this literature review, Hispanic demographic changes in the United States and in Texas are examined. Hispanics have accounted for large changes in population, population change, and proportion of population. Accordingly, the literature was reviewed regarding Hispanic immigrants, both authorized and non-authorized immigrants. The issue of…

  8. Guide to Population Issues for Students and Teachers [and] Curriculum Guide.

    ERIC Educational Resources Information Center

    Facing the Future, Lopez Island, WA.

    As the world grapples with increasing environmental, social, and security problems, population is rarely considered a cause or contributing factor. The relationship of population to the human condition, and to the condition of the Earth, is often subtle and complex. But population growth affects almost every aspect of life from education to…

  9. Innovations in Classroom Teaching: How to Teach Population Education Course to Secondary School Students in China.

    ERIC Educational Resources Information Center

    Yue-Xiu, Feng

    1983-01-01

    Discusses curriculum/strategies used to teach a population education course in China. Sixteen lessons (one 45-minute lesson/week) are conducted to foster correct outlook and responsible attitude toward China's population situation, thereby promoting moral, intellectual, and physical development. Population education in other courses, student…

  10. The Dominance Concept Inventory: A Tool for Assessing Undergraduate Student Alternative Conceptions about Dominance in Mendelian and Population Genetics

    PubMed Central

    Perez, Kathryn E.; Price, Rebecca M.

    2014-01-01

    Despite the impact of genetics on daily life, biology undergraduates understand some key genetics concepts poorly. One concept requiring attention is dominance, which many students understand as a fixed property of an allele or trait and regularly conflate with frequency in a population or selective advantage. We present the Dominance Concept Inventory (DCI), an instrument to gather data on selected alternative conceptions about dominance. During development of the 16-item test, we used expert surveys (n = 12), student interviews (n = 42), and field tests (n = 1763) from introductory and advanced biology undergraduates at public and private, majority- and minority-serving, 2- and 4-yr institutions in the United States. In the final field test across all subject populations (n = 709), item difficulty ranged from 0.08 to 0.84 (0.51 ± 0.049 SEM), while item discrimination ranged from 0.11 to 0.82 (0.50 ± 0.048 SEM). Internal reliability (Cronbach's alpha) was 0.77, while test–retest reliability values were 0.74 (product moment correlation) and 0.77 (intraclass correlation). The prevalence of alternative conceptions in the field tests shows that introductory and advanced students retain confusion about dominance after instruction. All measures support the DCI as a useful instrument for measuring undergraduate biology student understanding and alternative conceptions about dominance. PMID:26086665

  11. The Roles of Population, Place, and Institution in Student Diversity in American Higher Education

    PubMed Central

    Franklin, Rachel S.

    2014-01-01

    Student racial and ethnic diversity in higher education is an important and timely topic, as institutions, policy-makers, and economists increasingly recognize the value that accrues at many levels of having a skilled and diverse student body and workforce. Students benefit from learning in a diverse environment; firms may benefit from a diverse workforce; and more demographically diverse regions make experience higher rates of economic growth. However, the forces governing institution-level student diversity are poorly understood, as little prior research on the topic exists. This paper uses school enrollment data to parse out the contribution institutional characteristics, geographical setting, and local demographic characteristics make to student body diversity at each level of study. Results indicate that geographical location and local demographic composition play a role in student body diversity, as do the type and orientation of the institution. Institutional characteristics explain a lot of the variation in student body diversity and actual location of schools matters less than the demographic composition of young people around that location. Two broad conclusions emerge with regard to schools seeking to increase their student diversity. First, some may find their efforts hampered by circumstances outside their control (location, for example). Second, the influence of public/private status and even school size suggest further research on the ways in which these factors influence student diversity so that eventual policy action can be more effective. PMID:25425748

  12. Smoking Cessation Delivered by Medical Students Is Helpful to Homeless Population

    ERIC Educational Resources Information Center

    Spector, Andrew; Alpert, Hilary; Karam-Hage, Maher

    2007-01-01

    Objective: The authors pilot a smoking-cessation outreach for the homeless that extends medical students' tobacco cessation education. Method: In this prospective study, second-year medical students administered cognitive behavior therapy or unstructured support to homeless subjects to help them quit smoking. Self-report and biological measures…

  13. The Challenges of the Future: Ethical Issues in a Changing Student Population.

    ERIC Educational Resources Information Center

    Lawler, Patricia A.

    The increase in the numbers of adult students studying on college and university campuses has created a new set of ethical and administrative challenges for those institutions. Projections for the nineties suggest 50 percent of enrollment will be adults. Characteristically, adult students perceive themselves to be responsible for their own lives;…

  14. Characteristics of the Population of Deaf and Hard of Hearing Students with Emotional Disturbance in Illinois

    ERIC Educational Resources Information Center

    Sinnott, C. L.; Jones, T. W.

    2005-01-01

    The study summarizes a database for the years 1994-1999 on deaf and hard of hearing students in Illinois with a diagnosis of emotional disturbance (N = 115). Data are reported on the group's demographic, domestic, etiologic, communication-related, and intervention-related characteristics. These dually diagnosed students differed from Illinois's…

  15. CHARACTERISTICS OF THE STUDENT POPULATION, UNIVERSITY OF ALABAMA RESIDENT CENTER, HUNTSVILLE, ALABAMA.

    ERIC Educational Resources Information Center

    FRANKLIN, ELTON

    THE MAIN PURPOSE OF THIS 1959 SURVEY WAS TO ANALYZE SOME OF THE BASIC CHARACTERISTICS OF STUDENTS AT THE UNIVERSITY OF ALABAMA RESIDENT CENTER, HUNTSVILLE. FINDINGS WERE TABULATED IN SUMMARY FORM AND BY MAJOR FIELDS OF ACADEMIC INTEREST. OF THE STUDENTS (LARGELY YOUNG ADULTS), 51 PERCENT WERE IN ENGINEERING. ONLY 16 PERCENT WERE FEMALE. MOST…

  16. An Analysis of the Student Population Enrolled in Alternative Delivery System Courses.

    ERIC Educational Resources Information Center

    Holleman, John J.

    Vista College, a non-campus college which offers classes in a number of community locations, has developed several strategies to meet the needs of student groups not previously served fully by the Peralta Community College District, including worker-students, older adults, the handicapped, and women. A survey was conducted in 1981 to obtain…

  17. The Role of the Agricultural Educator in Meeting the Needs of a Diverse Student Population.

    ERIC Educational Resources Information Center

    Conroy, Carol A.; Bruening, Thomas H.

    A study examined factors associated with achievement for African-American eighth graders and whether differences existed relative to poverty status and depth of poverty. Data were extracted from the National Educational Longitudinal Study of 1988. An independent data set of 3,009 students was created including information for students identifying…

  18. An Empirically Supported Program to Prevent Suicide in a College Student Population

    ERIC Educational Resources Information Center

    Joffe, Paul

    2008-01-01

    In the fall of 1984, the University of Illinois instituted a formal program to reduce the rate of suicide among its enrolled students. At the core of the program is a policy that requires any student who threatens or attempts suicide to attend four sessions of professional assessment. The consequences for failing to comply with the program include…

  19. A Meta-Analytic Evaluation of the FRIENDS Program for Preventing Anxiety in Student Populations

    ERIC Educational Resources Information Center

    Maggin, Daniel M.; Johnson, Austin H.

    2014-01-01

    The purpose of this review was to evaluate the methodological strength and overall effectiveness of the research underlying the FRIENDS program for preventing anxiety in students at low and elevated risk for developing anxiety disorders. Meta-analytic findings provided mixed results, with low-risk students exposed to the program having…

  20. Factors Influencing Successful Student Outcomes between Transfer and Native Populations in a Postsecondary Environment

    ERIC Educational Resources Information Center

    Tinney, Tina Molero

    2012-01-01

    Institutions of higher education have experienced increased scrutiny. Legislative and policy developments rapidly impact institutional accountability and student access. While various accountability measures are available to assess institutional quality and student success, information currently collected is not sufficient for a broader…

  1. Factorial and Structural Validity of Holland's Hexagonal Model for an Asian Student Population.

    ERIC Educational Resources Information Center

    Tay, Kenneth Kim; Hill, Joseph A.; Ward, Connie M.

    A study examined the utility of Holland's hexagonal model as a culturally appropriate theoretical framework for U.S. career psychologists working with Asian international students. Chinese-descent international students enrolled in three Southeastern universities (n=170) completed three instruments: Holland's Self-Directed Search (SDS), an…

  2. Student as Institutional Mirror: What Campuses Can Learn from Nontraditional Populations

    ERIC Educational Resources Information Center

    Davis, Jeff

    2011-01-01

    College campuses look different today, at the beginning of the twenty-first century, than they did 50 years ago. The buildings and signage may look almost the same, but the students who learn in those buildings definitely do not. Increased access and the diversity movement have resulted in younger and older students sitting side by side in the…

  3. Ohio's At-Risk Student Population: A Decade of Rising Risk

    ERIC Educational Resources Information Center

    Vesely, Randall S.

    2013-01-01

    Educators face increasing demands to raise student achievement, to improve classroom instruction, and to demonstrate accountability in an environment of high stakes testing. However, meeting these demands is challenging in the face of numerous risk factors that jeopardize the academic success of elementary and secondary students. To that end, the…

  4. Factors associated with illicit drugs' lifetime and frequent/heavy use among students results from a population survey.

    PubMed

    Bitancourt, Tânia; Tissot, Maria Cristina Ribeiro Grilli; Fidalgo, Thiago Marques; Galduróz, José Carlos Fernandes; da Silveira Filho, Dartiu Xavier

    2016-03-30

    Substance use among teenage students and factors associated were investigated through a survey using a questionnaire adapted from the WHO's Program on Research and Reporting on the Epidemiology of Drug Dependence, additional questions on family factors and personal risks, and the Coopersmith Self-Esteem Inventory, adapted to Brazil. The target population consisted of 3891 10-22-year-old students from the city of Embu das Artes, São Paulo, Brazil. The prevalence of lifetime substance use was 26.7%. Most commonly used substances were energy drinks combined with alcohol (19%), solvents (11.2%) and marijuana (4.8%). Almost 60% of the students had already tried alcohol and 18.2% had tried tobacco. Factors associated to lifetime substance use were: lower self-esteem, going to nightclubs at least twice a week, use of alcohol, trying tobacco, bad relationship with the mother, permissive mothers, practicing sports as an obligation, working, and higher socioeconomic level. Concerning frequent/heavy substance use, chances were found to be higher among students who had use tobacco and alcohol, going to nightclubs at least twice a week, and those with lower self-esteem. Preventive actions concerning drug use should focus on avoiding the first experimentation, approaching family relationships, and improving students' self-esteem. PMID:26832836

  5. Underachieving Gifted Students and Ways to Improve School Performance of at Risk Student Population Who Have High Potential: Improving Writing Performance in Underachieving Gifted Students

    ERIC Educational Resources Information Center

    Brown-Anfelouss, Marjorie

    2012-01-01

    Giftedness has often been equated with being academically talented or being a high achiever in school. However, there is often concern about the gifted students who could be described as unmotivated and underachieving in one or many academic areas. At the Jones Street School, a school for gifted elementary students, the location of this study,…

  6. How Spanish Primary School Students Interpret the Concepts of Population and Species

    ERIC Educational Resources Information Center

    Jiménez-Tejada, María-Pilar; Sánchez-Monsalve, Cristina; González-García, Francisco

    2013-01-01

    This article presents research concerning the way in which primary school pupils in southern Spain interpret the concepts of population and species. The results show that, for the concept of population, there was an intense anthropocentrism in pupils' responses, while for the concept of species, only animals were considered as living…

  7. Identifying Rural Disadvantaged Gifted Students. Project SPRING: Special Populations Resource Information Network for the Gifted.

    ERIC Educational Resources Information Center

    Spicker, Howard H.; Poling, S. Nancy

    This manual was developed as part of a project to identify and serve the needs of gifted and talented economically disadvantaged elementary and secondary level populations. Section I presents a leader's manual for a workshop that discusses innovative procedures for identifying bright children in all cultures and populations. The workshop examines…

  8. Migraine and quality of life in high school students: a population-based study in Boukan, Iran.

    PubMed

    Abdollahpour, Ibrahim; Salimi, Yahya; Shushtari, Zahra Jorjoran

    2015-02-01

    The aim of the study was to estimate quality of life and determine the adjusted association of migraine with the quality of life in a sample of students. This population-based study was performed among 857 high school students in Boukan City (with a Kurdish language-speaking population, about 600 km west of the city of Tehran, Iran). The World Health Organization Quality of Life questionnaire was used along with International Headache Society criteria. Multiple linear regression models were applied. The mean scores of quality of life domains of physical health, psychological, environmental, and social relationships were 69.1 (standard deviation = 16.5), 61.5 (standard deviation = 18. 1), 66.3 (standard deviation = 20. 8), and 65.2 (standard deviation = 17. 8) out of 100, respectively. Migraine after adjusting for the other factors was associated significantly with the scores in the physical (P = .002), social (P = .002), and environmental (P = .033) domains. Migraine is associated with reducing the physical, environmental, and social aspects of the students' quality of life. PMID:24832399

  9. Students delivering health care to a vulnerable Appalachian population through interprofessional service-learning.

    PubMed

    Lee, Michelle L; Hayes, Patricia A; McConnell, Peggy; Henry, Robin M

    2013-01-01

    Interprofessional student service-learning experiences are integrated into the preventive care of older adult residents of public housing in Appalachia. Receiving a Health Resources and Services Administration grant provided the College of Nursing at East Tennessee State University the opportunity to expand interprofessional clinical experiences for students by partnering with the College of Pharmacy, the College of Clinical & Rehabilitative Health Sciences, and the local public housing authority. Select faculty from each college met and developed a plan to form student teams from all three colleges to conduct in-home comprehensive medical and nutrition assessments and medication chart reviews of high-risk older adults. Following the in-home visit, students and faculty discuss the assessment findings at planned interprofessional meetings. Students present their findings from each discipline's perspective and collaboratively set health priorities and develop intervention strategies and an inclusive follow-up plan. Excerpts from students' reflective narratives discussing the impact of the interprofessional service-learning experiences are shared. PMID:23362854

  10. A Cross Sectional and Longitudinal Study of Pharmacy Student Perceptions of Readiness to Serve Diverse Populations.

    PubMed

    Crawford, Stephanie Y; Awé, Clara; Tawk, Rima H; Simon Pickard, A

    2016-05-25

    Objective. To examine students' self-perceptions at different stages in a pharmacy curriculum of competence related to serving culturally diverse patients and to compare self-reported competence of a student cohort near the beginning and end of the degree program. Methods. Student perceptions across four pharmacy class years were measured in a cross-sectional survey, with a follow-up longitudinal survey of one cohort three years later. Results. Based on an 81.9% response rate (537/656), scores showed no attitude changes. Reported knowledge, skills, comfort in clinical encounters, and curricular preparedness increased across program years. Fourth-year (P4) pharmacy students reported the highest scores. Scores differed by gender, age, and race/ethnicity. Students in the fourth year scored lower on importance of diversity training. Conclusion. Improved perceptions of readiness (ie, knowledge and behavior) to serve diverse groups suggest the curriculum impacts these constructs, while the invariance of student attitudes and association of self-reports with programmatic outcomes warrant further investigation. PMID:27293229

  11. Tobacco Smoking in HIV-Infected versus General Population in France: Heterogeneity across the Various Groups of People Living with HIV

    PubMed Central

    Tron, Laure; Lert, France; Spire, Bruno; Dray-Spira, Rosemary

    2014-01-01

    Background Although the various groups of people living with HIV (PLWHIV) considerably differ regarding socioeconomic and behavioral characteristics, their specificities regarding tobacco smoking have been poorly investigated. We aimed to assess patterns of tobacco consumption across the various groups of PLWHIV and to compare them to the general population, accounting for the specific socioeconomic profile of PLWHIV. Methods We used data of the ANRS-Vespa2 study, a national representative survey on PLWHIV conducted in France in 2011. Prevalence of past and current tobacco consumption, heavy smoking and strong nicotine dependence were assessed among the various groups of PLWHIV as defined by transmission category, gender and geographic origin, and compared to the French general population using direct standardization and multivariate Poisson regression models, accounting for gender, age, education and geographic origin. Results Among the 3,019 participants aged 18–85 years (median time since HIV diagnosis: 12 years), 37.5% were current smokers and 22.1% were past smokers, with marked differences across the various groups of PLWHIV. Compared to the general population, the prevalence of regular smoking was increased among HIV-infected men who have sex with men (MSM) (adjusted prevalence rate ratio (aPRR): 1.19, 95% confidence interval (95% CI): 1.07–1.32), French-native women (aPRR: 1.32, 95% CI: 1.10–1.57), and heterosexual French-native men (although not significantly, aPRR: 1.19, 95% CI: 0.98–1.45). Additionally, HIV-infected MSM were significantly less likely to be ex-smokers (aPRR: 0.73, 95% CI: 0.64–0.82) than the general population and similar trends were observed among heterosexual French-native men (aPRR: 0.89, 95% CI: 0.78–1.02) and women (aPRR: 0.84, 95% CI: 0.70–1.01). HIV-infected sub-Saharan African migrants were less likely to be regular smokers than the general population. Conclusions Smoking constitutes a major concern in various groups

  12. Population heterogeneity of trait anger and differential associations of trait anger facets with borderline personality features, neuroticism, depression, Attention Deficit Hyperactivity Disorder (ADHD), and alcohol problems.

    PubMed

    Lubke, Gitta H; Ouwens, Klaasjan G; de Moor, Marleen H M; Trull, Timothy J; Boomsma, Dorret I

    2015-12-15

    Anger is an emotion consisting of feelings of variable intensity ranging from mild irritation to intense fury. High levels of trait anger are associated with a range of psychiatric, interpersonal, and health problems. The objectives of this study were to explore heterogeneity of anger as measured by the Spielberger Trait Anger Scale (STAS), and to assess the association of the different anger facets with a selection of psychiatric disorders covering externalizing and internalizing problems, personality disorders, and substance use. Factor mixture models differentiated between a high and low scoring class (28% vs. 72%), and between three factors (anger-temperament, anger-reaction, and immediacy of an anger response). Whereas all psychiatric scales correlated significantly with the STAS total score, regressing the three STAS factors on psychiatric behaviors model showed a more detailed pattern. Only borderline affect instability and depression were significantly associated with all three factors in both classes whereas other problem behaviors were associated only with 1 or 2 of the factors. Alcohol problems were associated with immediacy only in the high scoring class, indicating a non-linear relation in the total sample. Taking into account these more specific associations is likely to be beneficial when investigating differential treatment strategies. PMID:26454404

  13. Simulating Population Growth.

    ERIC Educational Resources Information Center

    Byington, Scott

    1997-01-01

    Presents a strategy to help students grasp the important implications of population growth. Involves an interactive demonstration that allows students to experience exponential and logistic population growth followed by a discussion of the implications of population-growth principles. (JRH)

  14. Predicting Population Curves.

    ERIC Educational Resources Information Center

    Bunton, Matt

    2003-01-01

    Uses graphs to involve students in inquiry-based population investigations on the Wisconsin gray wolf. Requires students to predict future changes in the wolf population, carrying capacity, and deer population. (YDS)

  15. Multi-event capture-recapture modeling of host-pathogen dynamics among European rabbit populations exposed to myxoma and Rabbit Hemorrhagic Disease Viruses: common and heterogeneous patterns.

    PubMed

    Santoro, Simone; Pacios, Isa; Moreno, Sacramento; Bertó-Moran, Alejandro; Rouco, Carlos

    2014-01-01

    Host-pathogen epidemiological processes are often unclear due both to their complexity and over-simplistic approaches used to quantify them. We applied a multi-event capture-recapture procedure on two years of data from three rabbit populations to test hypotheses about the effects on survival of, and the dynamics of host immunity to, both myxoma virus and Rabbit Hemorrhagic Disease Virus (MV and RHDV). Although the populations shared the same climatic and management conditions, MV and RHDV dynamics varied greatly among them; MV and RHDV seroprevalences were positively related to density in one population, but RHDV seroprevalence was negatively related to density in another. In addition, (i) juvenile survival was most often negatively related to seropositivity, (ii) RHDV seropositives never had considerably higher survival, and (iii) seroconversion to seropositivity was more likely than the reverse. We suggest seropositivity affects survival depending on trade-offs among antibody protection, immunosuppression and virus lethality. Negative effects of seropositivity might be greater on juveniles due to their immature immune system. Also, while RHDV directly affects survival through the hemorrhagic syndrome, MV lack of direct lethal effects means that interactions influencing survival are likely to be more complex. Multi-event modeling allowed us to quantify patterns of host-pathogen dynamics otherwise difficult to discern. Such an approach offers a promising tool to shed light on causative mechanisms. PMID:24708296

  16. Multi-event capture–recapture modeling of host–pathogen dynamics among European rabbit populations exposed to myxoma and Rabbit Hemorrhagic Disease Viruses: common and heterogeneous patterns

    PubMed Central

    2014-01-01

    Host–pathogen epidemiological processes are often unclear due both to their complexity and over-simplistic approaches used to quantify them. We applied a multi-event capture–recapture procedure on two years of data from three rabbit populations to test hypotheses about the effects on survival of, and the dynamics of host immunity to, both myxoma virus and Rabbit Hemorrhagic Disease Virus (MV and RHDV). Although the populations shared the same climatic and management conditions, MV and RHDV dynamics varied greatly among them; MV and RHDV seroprevalences were positively related to density in one population, but RHDV seroprevalence was negatively related to density in another. In addition, (i) juvenile survival was most often negatively related to seropositivity, (ii) RHDV seropositives never had considerably higher survival, and (iii) seroconversion to seropositivity was more likely than the reverse. We suggest seropositivity affects survival depending on trade-offs among antibody protection, immunosuppression and virus lethality. Negative effects of seropositivity might be greater on juveniles due to their immature immune system. Also, while RHDV directly affects survival through the hemorrhagic syndrome, MV lack of direct lethal effects means that interactions influencing survival are likely to be more complex. Multi-event modeling allowed us to quantify patterns of host–pathogen dynamics otherwise difficult to discern. Such an approach offers a promising tool to shed light on causative mechanisms. PMID:24708296

  17. Heterogeneity in Melanoma.

    PubMed

    Shannan, Batool; Perego, Michela; Somasundaram, Rajasekharan; Herlyn, Meenhard

    2016-01-01

    Melanoma is among the most aggressive and therapy-resistant human cancers. While great strides in therapy have generated enthusiasm, many challenges remain. Heterogeneity is the most pressing issue for all types of therapy. This chapter summarizes the clinical classification of melanoma, of which the research community now adds additional layers of classifications for better diagnosis and prediction of therapy response. As the search for new biomarkers increases, we expect that biomarker analyses will be essential for all clinical trials to better select patient populations for optimal therapy. While individualized therapy that is based on extensive biomarker analyses is an option, we expect in the future genetic and biologic biomarkers will allow grouping of melanomas in such a way that we can predict therapy outcome. At this time, tumor heterogeneity continues to be the major challenge leading inevitably to relapse. To address heterogeneity therapeutically, we need to develop complex therapies that eliminate the bulk of the tumor and, at the same time, the critical subpopulations. PMID:26601857

  18. Bringing Lunar and Planetary Science and Exploration to Underrepresented and Underutilized Student Populations

    NASA Astrophysics Data System (ADS)

    Levine, A. S.

    2007-03-01

    In order to reach the nation's best talent and brainpower, NASA must inform and inspire all populations including those that have been underutilized and underserved in the past, such as females, African-Americans and Native Americans.

  19. A Cross Sectional and Longitudinal Study of Pharmacy Student Perceptions of Readiness to Serve Diverse Populations

    PubMed Central

    Awé, Clara; Tawk, Rima H.; Simon Pickard, A.

    2016-01-01

    Objective. To examine students’ self-perceptions at different stages in a pharmacy curriculum of competence related to serving culturally diverse patients and to compare self-reported competence of a student cohort near the beginning and end of the degree program. Methods. Student perceptions across four pharmacy class years were measured in a cross-sectional survey, with a follow-up longitudinal survey of one cohort three years later. Results. Based on an 81.9% response rate (537/656), scores showed no attitude changes. Reported knowledge, skills, comfort in clinical encounters, and curricular preparedness increased across program years. Fourth-year (P4) pharmacy students reported the highest scores. Scores differed by gender, age, and race/ethnicity. Students in the fourth year scored lower on importance of diversity training. Conclusion. Improved perceptions of readiness (ie, knowledge and behavior) to serve diverse groups suggest the curriculum impacts these constructs, while the invariance of student attitudes and association of self-reports with programmatic outcomes warrant further investigation. PMID:27293229

  20. White blood cell count, sex and age are major determinants of heterogeneity of platelet indices in an adult general population: results from the MOLI-SANI project

    PubMed Central

    Santimone, Iolanda; Di Castelnuovo, Augusto; De Curtis, Amalia; Spinelli, Maria; Cugino, Daniela; Gianfagna, Francesco; Zito, Francesco; Donati, Maria Benedetta; Cerletti, Chiara; de Gaetano, Giovanni; Iacoviello, Licia

    2011-01-01

    Background The understanding of non-genetic regulation of platelet indices - platelet count, plateletcrit, mean platelet volume, and platelet distribution width - is limited. The association of these platelet indices with a number of biochemical, environmental and clinical variables was studied in a large cohort of the general population. Design and Methods Men and women (n=18,097, 52% women, 56±12 years) were randomly recruited from various villages in Molise (Italy) in the framework of the population-based cohort study “Moli-sani”. Hemochromocytometric analyses were performed using an automatic analyzer (Beckman Coulter, IL, Milan, Italy). Associations of platelet indices with dependent variables were investigated by multivariable linear regression analysis. Results Full models including age, sex, body mass index, blood pressure, smoking, menopause, white and red blood cell counts, mean corpuscular volume, D-dimers, C-reactive protein, high-density lipoproteins, low-density lipoproteins, triglycerides, glucose, and drug use explained 16%, 21%, 1.9% and 4.7% of platelet count, plateletcrit, mean platelet volume and platelet distribution width variability, respectively; variables that appeared to be most strongly associated were white blood cell count, age, and sex. Platelet count, mean platelet volume and plateletcrit were positively associated with white blood cell count, while platelet distribution width was negatively associated with white blood cell count. Platelet count and plateletcrit were also positively associated with C-reactive protein and D-dimers (P<0.0001). Each of the other variables, although associated with platelet indices in a statistically significant manner, only explained less than 0.5% of their variability. Platelet indices varied across Molise villages, independently of any other platelet count determinant or characteristics of the villages. Conclusions The association of platelet indices with white blood cell count, C-reactive protein

  1. Positive Mental Health and Well-Being among a Third Level Student Population

    PubMed Central

    Davoren, Martin P.; Fitzgerald, Eimear; Shiely, Frances; Perry, Ivan J.

    2013-01-01

    Introduction Much research on the health and well-being of third level students is focused on poor mental health leading to a dearth of information on positive mental health and well-being. Recently, the Warwick Edinburgh Mental Well-being scale (WEMWBS) was developed as a measurement of positive mental health and well-being. The aim of this research is to investigate the distribution and determinants of positive mental health and well-being in a large, broadly representative sample of third level students using WEMWBS. Methods Undergraduate students from one large third level institution were sampled using probability proportional to size sampling. Questionnaires were distributed to students attending lectures in the randomly selected degrees. A total of 2,332 self-completed questionnaires were obtained, yielding a response rate of 51% based on students registered to relevant modules and 84% based on attendance. One-way ANOVAs and multivariate logistic regression were utilised to investigate factors associated with positive mental health and well-being. Results The sample was predominantly female (62.66%), in first year (46.9%) and living in their parents’ house (42.4%) or in a rented house or flat (40.8%). In multivariate analysis adjusted for age and stratified by gender, no significant differences in WEMWBS score were observed by area of study, alcohol, smoking or drug use. WEMWBS scores were higher among male students with low levels of physical activity (p=0.04). Men and women reporting one or more sexual partners (p<0.001) were also more likely to report above average mental health and well-being. Conclusion This is the first study to examine positive mental health and well-being scores in a third level student sample using WEMWBS. The findings suggest that students with a relatively adverse health and lifestyle profile have higher than average mental health and well-being. To confirm these results, this work needs to be replicated across other third level

  2. Analysis of the Learning Styles of Diverse Student Populations and Implications for Higher Education Instructional Change

    ERIC Educational Resources Information Center

    Novogrodsky, Dorothy

    2012-01-01

    Higher education is one of the last institutions of learning to embrace the challenge of learner diversity that exists everywhere today (Dunn & Griggs, 2000; Rowley, Lujan, Dolence, 1998). This investigation explored the relationships between perceived preferred instructional strategies and student learning styles of learning-style aware…

  3. Career Education for Handicapped Students: A Suggested Approach. Technical Assistance Services: Illinois Special Needs Populations.

    ERIC Educational Resources Information Center

    Miller, Sidney R.; And Others

    This monograph describes a suggested approach to career education for handicapped students that focuses on two aspects of the career development process, career exploration and development of an academic program reflecting vocational needs. Discussed in the section on career exploration are career goals, the teacher-counselor role, individual…

  4. Training and Resource Needs of Teachers Who Provide HIV Education to Special Population Students

    ERIC Educational Resources Information Center

    Sawyer, Richard J.; Blake, Susan; Ledsky, Rebecca; Goodenow, Carol; Evans, Doug

    2004-01-01

    This study identified substantial training and resource needs for special education (SPED), transitional bilingual education/ English as a Second Language (TBE/ESL), and general education (GENED) HIV education teachers relative to providing appropriate, effective HIV education to students with disabilities (SWD) and language minority/Limited…

  5. Knowledge of and Attitudes toward Evolution in a Population of Community College Students

    ERIC Educational Resources Information Center

    Flower, Patricia

    2006-01-01

    Much attention has been given to the opposition toward the teaching of evolution at the K-12 level and the movement to include alternative theories, such as Intelligent Design (ID), in the science curriculum. However, very little is known regarding the attitudes of community college students toward the study of evolution and the inclusion of ID in…

  6. How One University Examined Graduation Rates of Its Undergraduate Student Population

    ERIC Educational Resources Information Center

    Paterson, Nicola; Gordon, Garvin

    2010-01-01

    The Office of Planning and Institutional Research (OPAIR), at the University of the West Indies, Mona Campus was asked to undertake an analysis of student throughput rates as part of a University-wide initiative involving the three campuses. Each Campus was provided with a template and guidelines for reporting the data. The exercise was intended…

  7. Students Delivering Health Care to a Vulnerable Appalachian Population through Interprofessional Service-Learning

    ERIC Educational Resources Information Center

    Lee, Michelle L.; Hayes, Patricia A.; McConnell, Peggy; Henry, Robin M.

    2013-01-01

    Interprofessional student service-learning experiences are integrated into the preventive care of older adult residents of public housing in Appalachia. Receiving a Health Resources and Services Administration grant provided the College of Nursing at East Tennessee State University the opportunity to expand interprofessional clinical experiences…

  8. Profile of the Graduate Student Population in U.S. Medical Schools.

    ERIC Educational Resources Information Center

    Ammons, Stanley W.; Kelly, Douglas E.

    1997-01-01

    Medical school surveys in 1994-95 and 1995-96 (n=104 schools) found that PhDs accounted for 25-30% of medical school enrollments; in some institutions, it was about half. Trend is toward interdisciplinary rather than departmental degrees. Number of student supported by National Institutes of Health (NIH) research grants was nearly twice that for…

  9. An Overlooked Population in Community College: International Students' (In)Validation Experiences With Academic Advising

    ERIC Educational Resources Information Center

    Zhang, Yi

    2016-01-01

    Objective: Guided by validation theory, this study aims to better understand the role that academic advising plays in international community college students' adjustment. More specifically, this study investigated how academic advising validates or invalidates their academic and social experiences in a community college context. Method: This…

  10. A Profile of the Aboriginal and Torres Strait Islander Higher Education Student Population

    ERIC Educational Resources Information Center

    Wilks, Judith; Wilson, Katie

    2015-01-01

    This paper brings together recent statistics relating to the participation of Aboriginal and Torres Strait Islander students in higher education. A number of key statistical realities relating to their enrolment into, retention during, and completion of, their university courses are depicted. Foremost among these realities is that despite…

  11. All Means All: Including Students from Special Populations in School to Work Programs.

    ERIC Educational Resources Information Center

    Kellogg, Ann, Ed.

    This resource guide assists Wisconsin educators in successfully including students with disabilities in school-to-work activities with appropriate support services. Section 1 provides an overview of the School to Work Opportunities Act and Wisconsin's state plan for developing a comprehensive school-to-work system integrated with federal efforts…

  12. The Incidence of Potentially Gifted Students within a Special Education Population

    ERIC Educational Resources Information Center

    Barnard-Brak, Lucy; Johnsen, Susan K.; Hannig, Alyssa Pond; Wei, Tianlan

    2015-01-01

    From a sample of 13,176 children with disabilities who were a part of the Special Education Elementary Longitudinal Study, 330 students achieved a score at the 90th percentile or higher on the Woodcock-Johnson III. These children represent some 9.1% of children who have disabilities nationally and who might be identified as gifted or academically…

  13. Writing to Learn Ecology: A Study of Three Populations of College Students

    ERIC Educational Resources Information Center

    Balgopal, Meena M.; Wallace, Alison M.; Dahlberg, Steven

    2012-01-01

    Being an ecologically literate citizen involves making decisions that are based on ecological knowledge and accepting responsibility for personal actions. Using writing-to-learn activities in college science courses, we asked students to consider personal dilemmas that they or others might have in response to how human choices can impact coastal…

  14. Validity Evidence for the Use of Holland's Vocational Personality Types in College Student Populations

    ERIC Educational Resources Information Center

    Floyd, Nancy D.

    2012-01-01

    Higher education in the United States is replete with inventories and instruments designed to help administrators to identify students who are more likely to succeed in college and to tailor the higher education experience to foster this success. One area of research involves the Holland vocational personality type (Holland 1973, 1985, 1997)…

  15. Testing Officials Again Tackle Accommodations and Exclusions for Special Student Populations

    ERIC Educational Resources Information Center

    Cavanagh, Sean

    2008-01-01

    Perhaps no topic has as thoroughly vexed officials who oversee the nation's leading test of academic progress as the wide variation among states and cities in the proportion of students with disabilities and limited English proficiency whom they exclude from taking the exam or provide with special accommodations for it. The board that sets policy…

  16. English Language Learners: Experiences of Teachers of Students with Visual Impairments Who Work with This Population

    ERIC Educational Resources Information Center

    Topor, Irene; Rosenblum, L. Penny

    2013-01-01

    Introduction: This article presents a study that gathered data from 66 teachers of students with visual impairments about their preparation to work with children who are visually impaired and are learning English, and their knowledge of instructional strategies and methods of instruction. Methods: An online five-part survey was available to…

  17. Heterogeneous Evolution of HIV-1 CRF01_AE in Men Who Have Sex with Men (MSM) and Other Populations in China

    PubMed Central

    Peng, Xiaorong; Wu, Haibo; Peng, Xiuming; Jin, Changzhong; Wu, Nanping

    2015-01-01

    Introduction The HIV epidemic in men who have sex with men (MSM) continues to grow in most countries. However, the phylodynamic and virological differences among HIV-1 strains circulating in MSM and other populations are not well characterized. Methods Nearly full-length genomes (NFLGs) of the HIV-1 CRF01_AE were obtained from the Los Alamos HIV database. Phylogenetic analyses were conducted using the NFLG, gag, pol and env genes, using the maximum likelihood method. Selection pressure analyses at the codon level were performed for each gene in the phylogenetic clusters using PAML. Results Sequences isolated from MSM in China clustered in Clusters 1 (92.5%) and 2 (85.71%). The major risk factor for Cluster 3 was heterosexual transmission (62.16%). The ratio of non-synonymous to synonymous substitutions in the env gene (0.7–0.75) was higher than the gag (0.26–0.34) or pol (0.21–0.26) genes. In env gene, Cluster 1 (4.56×10-3subs/site/year) and 2 (6.01×10-3subs/site/year) had higher evolutionary rates than Cluster 3 (1.14×10-3subs/site/year). Positive selection affected 4.2–6.58% of the amino acid sites in the env gene. Two sites (HXB2:136 and 316) evolved similarly in Clusters 1 and 2, but not Cluster 3. Conclusion The HIV-1 CRF01_AE in MSM is evolving differently than in other populations. PMID:26623642

  18. Effects of the Just One Mentoring Program on Student Persistence at Milwaukee Area Technical College

    ERIC Educational Resources Information Center

    Palmer, Emma

    2015-01-01

    This dissertation investigated the effects of the intervention of the Just One Mentoring Program on student persistence in completing their career programs. The population for this study consisted of a heterogeneous group of students enrolled in the Just One Mentoring Program during summer 2003 through fall 2006 at a community college located in…

  19. Increasing Accessibility: Lessons Learned in Retaining Special Population Students in Canada

    ERIC Educational Resources Information Center

    Smith, Clayton; Gottheil, Susan

    2011-01-01

    In Canada, changing demographics and increased competition--as well as social values based on equity--have inspired efforts to increase the postsecondary education (PSE) participation rates of youths from under-represented/under-served groups. Despite its population having the highest level of educational attainment among those of OECD countries,…

  20. School Enrollment--Social and Economic Characteristics of Students: October 1988 and 1987. Current Population Reports.

    ERIC Educational Resources Information Center

    Bruno, Rosalind R.

    1990-01-01

    This report presents detailed tabulations of statistical data on school enrollment of the civilian noninstitutional population in October 1987 and 1988. The following enrollments are reported: (1) nursery school; (2) kindergarten; (3) elementary school; (4) high school; and (5) college and professional school. The following personal…

  1. Prevalence of Residential Dampness and Mold Exposure in a University Student Population

    PubMed Central

    Lanthier-Veilleux, Mathieu; Généreux, Mélissa; Baron, Geneviève

    2016-01-01

    The impact of residential dampness or mold on respiratory health is well established but few studies have focused on university students. This study aims to: (a) describe the prevalence of exposure to residential dampness or mold in university students according to socio-geographic factors and (b) identify associated housing characteristics. A web survey was conducted in 2014 among the 26,676 students registered at the Université de Sherbrooke (QC, Canada). Residential dampness and mold being closely intertwined, they were considered as a single exposure and assessed using a validated questionnaire. Exposure was compared according to socio-geographic and housing characteristics using chi-square tests and logistic regressions. Among the 2097 participants included in the study (response rate: 8.1%), over 80% were tenants. Residential exposure to dampness or mold was frequent (36.0%, 95% CI: 33.9–38.1). Marked differences for this exposure were noted according to home ownership (39.7% vs. 25.5% among tenants and owners respectively; OR = 1.92%, 95% CI: 1.54–2.38). Campus affiliation, household composition and the number of residents per building were associated with exposure to dampness or mold (p < 0.01), while sex and age were not. Exposure was also associated with older buildings, and buildings in need of renovations and lacking proper ventilation (p < 0.001). This study highlights the potential risk of university students suffering from mold-related health effects given their frequent exposure to this agent. Further research is needed to fully evaluate the mold-related health impact in this at risk group. PMID:26861364

  2. Prevalence of Residential Dampness and Mold Exposure in a University Student Population.

    PubMed

    Lanthier-Veilleux, Mathieu; Généreux, Mélissa; Baron, Geneviève

    2016-02-01

    The impact of residential dampness or mold on respiratory health is well established but few studies have focused on university students. This study aims to: (a) describe the prevalence of exposure to residential dampness or mold in university students according to socio-geographic factors and (b) identify associated housing characteristics. A web survey was conducted in 2014 among the 26,676 students registered at the Université de Sherbrooke (QC, Canada). Residential dampness and mold being closely intertwined, they were considered as a single exposure and assessed using a validated questionnaire. Exposure was compared according to socio-geographic and housing characteristics using chi-square tests and logistic regressions. Among the 2097 participants included in the study (response rate: 8.1%), over 80% were tenants. Residential exposure to dampness or mold was frequent (36.0%, 95% CI: 33.9-38.1). Marked differences for this exposure were noted according to home ownership (39.7% vs. 25.5% among tenants and owners respectively; OR = 1.92%, 95% CI: 1.54-2.38). Campus affiliation, household composition and the number of residents per building were associated with exposure to dampness or mold (p < 0.01), while sex and age were not. Exposure was also associated with older buildings, and buildings in need of renovations and lacking proper ventilation (p < 0.001). This study highlights the potential risk of university students suffering from mold-related health effects given their frequent exposure to this agent. Further research is needed to fully evaluate the mold-related health impact in this at risk group. PMID:26861364

  3. Heterogeneous pumice populations in the 2.08-Ma Cerro Galán Ignimbrite: Implications for magma recharge and ascent preceding a large-volume silicic eruption

    USGS Publications Warehouse

    Wright, Heather M.; Folkes, Christopher B.; Cas, Ray A.F.; Cashman, Katharine V.

    2011-01-01

    Triggering mechanisms of large silicic eruptions remain a critical unsolved problem. We address this question for the ~2.08-Ma caldera-forming eruption of Cerro Galán volcano, Argentina, which produced distinct pumice populations of two colors: grey (5%) and white (95%) that we believe may hold clues to the onset of eruptive activity. We demonstrate that the color variations correspond to both textural and compositional variations between the clast types. Both pumice types have bulk compositions of high-K, high-silica dacite to low-silica rhyolite, but there are sufficient compositional differences (e.g., ~150 ppm lower Ba at equivalent SiO2 content and 0.03 wt.% higher TiO2 in white pumice than grey) to suggest that the two pumice populations are not related by simple fractionation. Trace element concentrations in crystals mimic bulk variations between clast types, with grey pumice containing elevated Ba, Cu, Pb, and Zn concentrations in both bulk samples (average Cu, Pb, and Zn concentrations are 27, 35, and 82 in grey pumice vs. 11, 19, and 60 in white pumice) and biotite phenocrysts and white pumice showing elevated Li concentrations in biotite and plagioclase phenocrysts. White and grey clasts are also texturally distinct: White pumice clasts contain abundant phenocrysts (44–57%), lack microlites, and have highly evolved groundmass glass compositions (76.4–79.6 wt.% SiO2), whereas grey pumice clasts contain a lower percentage of phenocrysts/microphenocrysts (35–49%), have abundant microlites, and have less evolved groundmass glass compositions (69.4–73.8 wt.% SiO2). There is also evidence for crystal transfer between magma producing white and grey pumice. Thin highly evolved melt rims surround some fragmental crystals in grey pumice clasts and appear to have come from magma that produced white pumice. Furthermore, based on crystal compositions, white bands within banded pumice contain crystals originating in grey magma. Finally, only grey

  4. Explanations of sleep paralysis among Egyptian college students and the general population in Egypt and Denmark.

    PubMed

    Jalal, Baland; Simons-Rudolph, Joseph; Jalal, Bamo; Hinton, Devon E

    2014-04-01

    This cross-cultural study compared explanations of sleep paralysis (SP) in two countries and two groups with different levels of education in one country. Comparisons were made between individuals having experienced SP at least once in a lifetime from Cairo, Egypt (n = 89), Copenhagen, Denmark (n = 59), and the American University in Cairo, Egypt (n = 44). As hypothesized, participants from the general Egyptian population were more likely to endorse supernatural causal explanation of their SP compared to participants from Denmark; participants from the American University in Cairo were less likely to endorse supernatural causes of their SP compared to participants from the general Egyptian population. Moreover, participants from the American University in Cairo were marginally significantly more likely to endorse supernatural causes of their SP compared to participants from Denmark. Additionally, we explored which culturally bound explanations and beliefs about SP existed in Egypt and Denmark. We found that nearly half (48%) of the participants from the general Egyptian population believed their SP to be caused by the Jinn, a spirit-like creature with roots in Islamic tradition, which constitutes a culturally bound interpretation of the phenomenology of SP in this region of the world. Case studies are presented to illustrate these findings. PMID:24084761

  5. Evidence of hearing loss in a “normally-hearing” college-student population

    PubMed Central

    Le Prell, C. G.; Hensley, B.N.; Campbell, K. C. M.; Hall, J. W.; Guire, K.

    2011-01-01

    We report pure-tone hearing threshold findings in 56 college students. All subjects reported normal hearing during telephone interviews, yet not all subjects had normal sensitivity as defined by well-accepted criteria. At one or more test frequencies (0.25–8 kHz), 7% of ears had thresholds ≥25 dB HL and 12% had thresholds ≥20 dB HL. The proportion of ears with abnormal findings decreased when three-frequency pure-tone-averages were used. Low-frequency PTA hearing loss was detected in 2.7% of ears and high-frequency PTA hearing loss was detected in 7.1% of ears; however, there was little evidence for “notched” audiograms. There was a statistically reliable relationship in which personal music player use was correlated with decreased hearing status in male subjects. Routine screening and education regarding hearing loss risk factors are critical as college students do not always self-identify early changes in hearing. Large-scale systematic investigations of college students’ hearing status appear to be warranted; the current sample size was not adequate to precisely measure potential contributions of different sound sources to the elevated thresholds measured in some subjects. PMID:21288064

  6. Survey of mobile phone use and their chronic effects on the hearing of a student population.

    PubMed

    Davidson, Harry C; Lutman, Mark E

    2007-03-01

    Mobile phone ownership and usage is now widespread and public concern has developed over possible harmful physiological effects of their use. This study aimed to investigate the prevalence of student mobile phone ownership and any possible chronic effects of usage on hearing, tinnitus and balance. Questionnaires for electronic self-completion were distributed to University of Southampton postgraduates, and 117 out of 160 returned met the criteria for analysis. A total of 94% were current mobile phone users, and only 2% had never used a mobile phone. Duration of ownership and daily usage ranged from 0-7 years and 0-45 minutes respectively. Text-messaging was more popular than talking. High or long-term users reported no worse hearing, tinnitus, or balance than low or short-term users. The results of this study confirm that the prevalence of mobile phone ownership amongst students is extremely high. However there appear to be no harmful effects of mobile phone usage on their audiovestibular systems within the range of exposure of the study, insofar as can be detected by the self-report method employed. PMID:17365064

  7. Mentors Are from Venus and Mars: Exploring the Benefits of Homogeneous and Heterogeneous Gender Pairings in the Mentoring Relationships of Female Senior Student Affairs Officers

    ERIC Educational Resources Information Center

    Jarnagin, Lea Marie

    2010-01-01

    While the number of women entering the student affairs profession has increased, gender equity at the senior level of leadership remains elusive in the student affairs profession. In comparison to their presence in graduate preparation programs and lower levels of administration women continue to lag behind men in their rate of advancement to the…

  8. Resource heterogeneity can facilitate cooperation

    PubMed Central

    Kun, Ádám; Dieckmann, Ulf

    2013-01-01

    Although social structure is known to promote cooperation, by locally exposing selfish agents to their own deeds, studies to date assumed that all agents have access to the same level of resources. This is clearly unrealistic. Here we find that cooperation can be maintained when some agents have access to more resources than others. Cooperation can then emerge even in populations in which the temptation to defect is so strong that players would act fully selfishly if their resources were distributed uniformly. Resource heterogeneity can thus be crucial for the emergence and maintenance of cooperation. We also show that resource heterogeneity can hinder cooperation once the temptation to defect is significantly lowered. In all cases, the level of cooperation can be maximized by managing resource heterogeneity. PMID:24088665

  9. Insomnia, Nightmares, and Chronotype as Markers of Risk for Severe Mental Illness: Results from a Student Population

    PubMed Central

    Sheaves, Bryony; Porcheret, Kate; Tsanas, Athanasios; Espie, Colin A.; Foster, Russell G.; Freeman, Daniel; Harrison, Paul J; Wulff, Katharina; Goodwin, Guy M.

    2016-01-01

    Study Objectives: To group participants according to markers of risk for severe mental illness based on subsyndromal symptoms reported in early adulthood and evaluate attributes of sleep across these risk categories. Methods: An online survey of sleep and psychiatric symptomatology (The Oxford Sleep Survey) was administered to students at one United Kingdom university. 1403 students (undergraduate and postgraduate) completed the survey. The median age was 21 (interquartile range = 20–23) and 55.60% were female. The cross-sectional data were used to cluster participants based on dimensional measures of psychiatric symptoms (hallucinations, paranoia, depression, anxiety, and (hypo)mania). High, medium, and low symptom groups were compared across sleep parameters: insomnia symptoms, nightmares, chronotype, and social jet lag. Results: Insomnia symptoms, nightmares frequency, and nightmare-related distress increased in a dose-response manner with higher reported subsyndromal psychiatric symptoms (low, medium, and high). The high-risk group exhibited a later chronotype (mid sleep point for free days) than the medium- or low-risk group. The majority of participants (71.7%) in the high-risk group screened positive for insomnia and the median nightmare frequency was two per 14 days (moderately severe pathology). Conclusions: Insomnia, nightmares, and circadian phase delay are associated with increased subsyndromal psychiatric symptoms in young people. Each is a treatable sleep disorder and might be a target for early intervention to modify the subsequent progression of psychiatric disorder. Citation: Sheaves B, Porcheret K, Tsanas A, Espie CA, Foster RG, Freeman D, Harrison PJ, Wulff K, Goodwin GM. Insomnia, nightmares, and chronotype as markers of risk for severe mental illness: results from a student population. SLEEP 2016;39(1):173–181. PMID:26350467

  10. Student Change, Program Change: Why SAT Scores Kept Falling.

    ERIC Educational Resources Information Center

    Turnbull, William W.

    This paper analyzes Scholastic Aptitude Test (SAT) score declines of two decades--the 1960s and 1970s. The importance of pervasive societal influences is accepted. A variety of data suggests, however, that the increase in school retention rates of poorly prepared students and the resulting heterogeneity of the high school population is a unifying…

  11. Heterogeneous Crystal Populations: Signatures, Genesis and Chronologies

    NASA Astrophysics Data System (ADS)

    Reid, M. R.; Vazquez, J. A.

    2005-12-01

    The ongoing development of accessory phase-based techniques helps to illuminate possible scenarios for the physical state of magmatic systems between eruptions. These, in turn, may aid in the detection of magmas in the crust. At Long Valley caldera, eastern California, ion microprobe analyses of 238U-230Th in zircon from the youthful Inyo Dome rhyolites show that even though their ages are mainly younger than the 760 k.y. old caldera-forming Bishop Tuff, they are significantly older than eruption (up to 200 k.y. and more). Do these ages date the timing of magma emplacement and show that liquid was present in the system for at least 200 k.y.? Or do the ages represent sampling by the ion beam of bimodal age domains, meaning that they could have been rapidly mobilized from voluminous crystal mushes residual after the Bishop Tuff (e.g., Hildreth, 2004)? Additionally or alternatively, could the "old" zircons be derived via assimilation of young, hydrothermally altered intrusive rocks (Schmitt and Simon, 2004)? The majority of 238U-206Pb analyses of zircons from Deer Mountain (13 of 20) are consistent with a single crystallization age that is somewhat older than previously obtained by 238U-230Th disequilibrium dating; the remaining zircon ages are younger and range to within error of the eruption age. The absence of Bishop Tuff-aged zircons indicates that if crystal mush contributes to the Inyo Dome rhyolites, its remobilization must have involved reheating to temperatures in excess of zircon saturation conditions (T>~800°C). Ion microprobe U-Th ages of allanites from South Deadman Dome range from 150 to <10 ka, in contrast to virtually all of the zircon ages which are >100 ka. The ca. 2-fold ranges in MnO/MgO and La/Nd in the same allanites overlap and extend the range of compositions we obtained for rhyolites from Toba caldera (Vazquez and Reid, 2005). The South Deadman Dome allanites could, by analogy to experimental results for a Toba rhyolite, have crystallized between the temperature interval of ~765°C to ~745°C. Taken at face value, the temperature-age distributions of allanite and zircon are therefore suggestive of a broad cooling trend. In detail, however, the T-t evolution defined by the allanites is one of a protracted interval of INCREASING temperature before eruption. We infer that intrusions of hotter, less evolved magma progressively hybridized the magma reservoir. Given the rarity with which zircons contemporary with the allanites have (as yet) been detected, the thermochemical conditions of that reservoir were sufficiently well buffered so that extensive (re)crystallization of zircon did not occur. Repose of a crystal-rich magma is indicated. This abstract is dedicated to the pioneering work of Stan Hart and Nobu Shimizu who showed how the Cameca 3f, Serial No. 1, could be used to investigate the isotopic and chemical evolution of crystals.

  12. Changes in Student Populations and Teacher Workforce in Low-Performing Chicago Schools Targeted for Reform. Summary. Issues & Answers. REL 2012-No. 123

    ERIC Educational Resources Information Center

    de la Torre, Marisa; Allensworth, Elaine; Jagesic, Sanja; Sebastian, James; Salmonowicz, Michael; Meyers, Coby; Gerdeman, R. Dean

    2012-01-01

    "Turning around" chronically low-performing schools is of increasing interest to educators and policymakers, as highlighted by the U.S. Department of Education's (2010) recent call to rapidly improve the nation's 5,000 lowest performing schools. Yet there is little rigorous research on changes in student populations and teacher workforce in…

  13. Changes in Student Populations and Teacher Workforce in Low-Performing Chicago Schools Targeted for Reform. Issues & Answers. REL 2012-No. 123

    ERIC Educational Resources Information Center

    de la Torre, Marisa; Allensworth, Elaine; Jagesic, Sanja; Sebastian, James; Salmonowicz, Michael; Meyers, Coby; Gerdeman, R. Dean

    2012-01-01

    "Turning around" chronically low-performing schools is of increasing interest to educators and policymakers, as highlighted by the U.S. Department of Education's (2010) recent call to rapidly improve the nation's 5,000 lowest performing schools. Yet there is little rigorous research on changes in student populations and teacher workforce in…

  14. The Nation's Report Card: Mega-States--An Analysis of Student Performance in the Five Most Heavily Populated States in the Nation. NCES 2013-450

    ERIC Educational Resources Information Center

    National Center for Education Statistics, 2013

    2013-01-01

    California, Florida, Illinois, New York, and Texas enroll close to 40 percent of the nation's public school students. The importance of these "Mega-States" goes beyond the sheer size of their population. They now serve more than half of the nation's English language learners (ELL), as well as some of the largest concentrations of children from…

  15. Rationale and Development of a General Population Well-Being Measure: Psychometric Status of the GP-CORE in a Student Sample

    ERIC Educational Resources Information Center

    Sinclair, Alice; Barkham, Michael; Evans, Chris; Connell, Janice; Audin, Kerry

    2005-01-01

    This paper presents the rationale, development, and psychometric status of a non-clinical self-report measure for the general population (GP) ? including students ? derived from the Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM) and hence termed the GP-CORE. In contrast to the CORE-OM, the GP-CORE does not comprise items…

  16. Salience of Nationality in Students' Spontaneous Self-Concept: A Comparative Study of a Nationally Homogeneous and a Heterogeneous School Context

    ERIC Educational Resources Information Center

    Murdock, Elke; Hirt, Franziska S.; Ferring, Dieter

    2014-01-01

    The study on which this article is based investigated the salience of nationality in adolescents' self-concept as a function of the diversity of the school context. According to the distinctiveness postulate, people selectively attend to and encode aspects that are most distinctive. We therefore predicted that students in the nationally…

  17. Academic Studies amid Violent Conflict: A Study of the Impact of Ongoing Conflict on a Student Population

    ERIC Educational Resources Information Center

    Ben-Tsur, Dalia

    2009-01-01

    This paper explores the impact of violent conflict on undergraduate students. In order to strengthen student resilience during periods of heightened insecurity, teachers and institutions must identify the difficulties that their students may be experiencing. Based on a case study of students in Israel, this paper identifies specific difficulties…

  18. Achievement of physical activity recommendation and activity levels in students of human medicine compared with the general Austrian population aged between 20 and 29 years.

    PubMed

    Lackinger, Christian; Dorner, Thomas Ernst

    2015-03-01

    Weekly 150 min of moderate to vigorous physical activity and muscle-strengthening activities are a major public health goal. The International Physical Activity Questionnaire-short form was applied in 467 students of the 4th year at the Medical University of Vienna and compared with subsamples of data from the Austrian Health Interview Survey, 795 subjects with and 1131 subjects without higher education aged 20-29 years. Median values for weekly total energy expenditure were 3083, 3048, and 3816 MET-minutes (P < 0.001) in medical students, higher and lower educated subjects of the general population. Energy expenditure with vigorous intensity was highest in medical students. A total of 39.4 % of medical students reached the minimum requirements of the national physical activity recommendations. Although medical students are taught those recommendation and are aware of their health benefits, only a minority reach them. If medical students engage in physical activity, they do it with higher intensity than the general population. PMID:25786602

  19. Very Low Ventricular Pacing Rates Can Be Achieved Safely in a Heterogeneous Pacemaker Population and Provide Clinical Benefits: The CANadian Multi-Centre Randomised Study-Spontaneous AtrioVEntricular Conduction pReservation (CAN-SAVE R) Trial

    PubMed Central

    Thibault, Bernard; Ducharme, Anique; Baranchuk, Adrian; Dubuc, Marc; Dyrda, Katia; Guerra, Peter G; Macle, Laurent; Mondésert, Blandine; Rivard, Léna; Roy, Denis; Talajic, Mario; Andrade, Jason; Nitzsché, Rémi; Khairy, Paul

    2015-01-01

    Background It is well recognized that right ventricular apical pacing can have deleterious effects on ventricular function. We performed a head-to-head comparison of the SafeR pacing algorithm versus DDD pacing with a long atrioventricular delay in a heterogeneous population of patients with dual-chamber pacemakers. Methods and Results In a multicenter prospective double-blinded randomized trial conducted at 10 centers in Canada, 373 patients, age 71±11 years, with indications for dual chamber DC pacemakers were randomized 1:1 to SafeR or DDD pacing with a long atrioventricular delay (250 ms). The primary objective was twofold: (1) reduction in the proportion of ventricular paced beats at 1 year; and (2) impact on atrial fibrillation burden at 3 years, defined as the ratio between cumulative duration of mode-switches divided by follow-up time. Statistical significance of both co-primary end points was required for the trial to be considered positive. At 1 year of follow-up, the median proportion of ventricular-paced beats was 4.0% with DDD versus 0% with SafeR (P<0.001). At 3 years of follow-up, the atrial fibrillation burden was not significantly reduced with SafeR versus DDD (median 0.00%, interquartile range [0.00% to 0.23%] versus median 0.01%, interquartile range [0.00% to 0.44%], respectively, P=0.178]), despite a persistent reduction in the median proportion of ventricular-paced beats (10% with DDD compared to 0% with SafeR). Conclusions A ventricular-paced rate <1% was safely achieved with SafeR in a population with a wide spectrum of indications for dual-chamber pacing. However, the lower percentage of ventricular pacing did not translate into a significant reduction in atrial fibrillation burden. Clinical Trial Registration URL: https://www.clinicaltrials.gov/ Unique identifier: NCT01219621. PMID:26206737

  20. Education Vital Signs: Population.

    ERIC Educational Resources Information Center

    Zakariya, Sally Banks

    1985-01-01

    Population changes and demographics shape the future of public schools. Includes statistics on ethnic makeup of student population, the projected baby boomlet, children of working mothers, households without children, and the aging population. (MD)

  1. Evidence-Based Practice Knowledge, Perceptions, and Behavior: A Multi-Institutional, Cross-Sectional Study of a Population of U.S. Dental Students.

    PubMed

    Straub-Morarend, Cheryl L; Wankiiri-Hale, Christine R; Blanchette, Derek R; Lanning, Sharon K; Bekhuis, Tanja; Smith, Becky M; Brodie, Abby J; Oliveira, Deise Cruz; Handysides, Robert A; Dawson, Deborah V; Spallek, Heiko

    2016-04-01

    The aim of this study was to help inform faculty and curriculum leaders in academic dental institutions about the knowledge, skills, perceptions, and behavior of an institutionally diverse population of dental students with respect to evidence-based practice (EBP). A survey utilizing the validated Knowledge, Attitudes, Access, and Confidence Evaluation instrument developed by Hendricson et al. was conducted in 2012 with fourth-year dental students at seven geographically dispersed U.S. dental schools. The survey addressed elements of EBP knowledge, attitudes toward EBP, behavior in accessing evidence, and perceptions of competence in statistical analysis. A total of 138 students from the seven schools participated. A slight majority of these students correctly responded to the knowledge of critical appraisal questions. While the students demonstrated positive attitudes about EBP, they did not report high levels of confidence in their critical appraisal skills. The findings also showed that the students accessed various sources of evidence with differing frequencies. The most frequently accessed resources were colleagues, the Internet (excluding Cochrane Database of Systematic Reviews), and textbooks. The results of this study help to identify areas for improvement in EBP education in order to advance dental students' preparation to become evidence-based practitioners. PMID:27037451

  2. The Role of African American Mentor Teachers in Preparing White Preservice Teachers for African American Student Populations

    ERIC Educational Resources Information Center

    Moule, Jean; Higgins, Karen M.

    2007-01-01

    How do we bridge the mismatch between teachers and students based on race and ethnicity currently in our nation's schools? The teaching force remains overwhelmingly White, while the percentage of K-12 students of color continues to rise. Because of cultural dissonance, teachers may not understand the needs of their students. This study shows…

  3. Effectiveness of the Brief Alcohol and Screening Intervention for College Students (BASICS) Program with a Mandated Population

    ERIC Educational Resources Information Center

    DiFulvio, Gloria T.; Linowski, Sally A.; Mazziotti, Janet S.; Puleo, Elaine

    2012-01-01

    Objective: This study evaluated the effectiveness of a large-scale intervention designed to reduce alcohol abuse among adjudicated college students. Participants: Participants were college students mandated to attend a Brief Alcohol Screening and Intervention for College Students (BASICS) program and a randomly selected comparison group of…

  4. An Evaluation of Behavioral Health Compliance and Microbial Risk Factors on Student Populations within a High-Density Campus

    ERIC Educational Resources Information Center

    Decker, Jody F.; Slawson, Robin M.

    2012-01-01

    Objective: The aim of this Canadian study was to assess student behavioral response to disease transmission risk, while identifying high microbial deposition/transmission sites. Participants: A student survey was conducted during October 2009. Methods: The methods included a survey of students to assess use of health services, vaccination…

  5. The Impact of Engagement with Extracurricular Activities on the Student Experience and Graduate Outcomes for Widening Participation Populations

    ERIC Educational Resources Information Center

    Stuart, Mary; Lido, Catherine; Morgan, Jessica; Solomon, Lucy; May, Steve

    2011-01-01

    This research examined extracurricular activity (ECA) effects on students' experiences, outcomes and future job prospects. A survey of diverse undergraduate students, along with alumni and potential employer interviews, revealed differences in students' engagement with ECAs beyond the classroom. Variations between "traditional" and "widening…

  6. Successes, Challenges and Lessons Learned for Recruiting, Engaging and Preparing a Diverse Student Population for 21st Century Careers in Ocean Sciences.

    NASA Astrophysics Data System (ADS)

    Clarkston, B. E.; Garza, C.

    2015-12-01

    Diversity within the Ocean Sciences workforce is still underperforming relative to other scientific disciplines, a problem that will be only be solved by recruiting, engaging and retaining a more diverse student population. The Monterey Bay Regional Ocean Science Research Experiences for Undergraduates program is housed at California State University, Monterey Bay (CSUMB), an HSI with strong connections to multiple regional community colleges and other Predominantly Undergraduate Institutions (PUIs) in the CSU system. From this unique position, 11 sophomore and junior-level undergraduate students are recruited per year from academic institutions where research opportunities in STEM are limited and from groups historically underrepresented in the Ocean Sciences, including women, underrepresented minorities, persons with disabilities, and veterans. During the program, students engage in a 10-week original research project guided by a faculty research mentor in one of four themes: Oceanography, Marine Biology and Ecology, Ocean Engineering, and Marine Geology. In addition to research, students engage in rigorous weekly professional development workshops in which they practice critical thinking, ethical decision-making, peer review, writing and oral communication skills. These workshops include tangible products such as an NSF-style proposal paper, Statement of Purpose and CV modelled for the SACNAS Travel Award Application, research abstract, scientific report and oral presentation. To help retain students in Ocean Sciences, students build community during the REU by living together in the CSUMB dormitories; post-REU, students stay connected through an online facebook group, LinkedIn page and group webinars. To date, the REU has supported 22 students in two cohorts (2014, 2015) and here we present successes, challenges and lessons learned for a program designed to prepare students for 21st century Ocean Science careers.

  7. Evidence-Based Practice Knowledge, Perceptions, and Behavior: A Multi-Institutional, Cross-Sectional Study of a Population of U.S. Dental Students

    PubMed Central

    Straub-Morarend, Cheryl L.; Wankiiri-Hale, Christine R.; Blanchette, Derek R.; Lanning, Sharon K.; Bekhuis, Tanja; Smith, Becky M.; Brodie, Abby J.; Oliveira, Deise Cruz; Handy-sides, Robert A.; Dawson, Deborah V.; Spallek, Heiko

    2016-01-01

    The aim of this study was to help inform faculty and curriculum leaders in academic dental institutions about the knowledge, skills, perceptions, and behavior of an institutionally diverse population of dental students with respect to evidence-based practice (EBP). A survey utilizing the validated Knowledge, Attitudes, Access, and Confidence Evaluation instrument developed by Hendricson et al. was conducted in 2012 with fourth-year dental students at seven geographically dispersed U.S. dental schools. The survey addressed elements of EBP knowledge, attitudes toward EBP, behavior in accessing evidence, and perceptions of competence in statistical analysis. A total of 138 students from the seven schools participated. A slight majority of these students correctly responded to the knowledge of critical appraisal questions. While the students demonstrated positive attitudes about EBP, they did not report high levels of confidence in their critical appraisal skills. The findings also showed that the students accessed various sources of evidence with differing frequencies. The most frequently accessed resources were colleagues, the Internet (excluding Cochrane Database of Systematic Reviews), and textbooks. The results of this study help to identify areas for improvement in EBP education in order to advance dental students’ preparation to become evidence-based practitioners. PMID:27037451

  8. Diffusion and Surface Reaction in Heterogeneous Catalysis

    ERIC Educational Resources Information Center

    Baiker, A.; Richarz, W.

    1978-01-01

    Ethylene hydrogenation on a platinum catalyst, electrolytically applied to a tube wall, is a good system for the study of the interactions between diffusion and surface reaction in heterogeneous catalysis. Theoretical background, apparatus, procedure, and student performance of this experiment are discussed. (BB)

  9. Analyzing and modeling heterogeneous behavior

    NASA Astrophysics Data System (ADS)

    Lin, Zhiting; Wu, Xiaoqing; He, Dongyue; Zhu, Qiang; Ni, Jixiang

    2016-05-01

    Recently, it was pointed out that the non-Poisson statistics with heavy tail existed in many scenarios of human behaviors. But most of these studies claimed that power-law characterized diverse aspects of human mobility patterns. In this paper, we suggest that human behavior may not be driven by identical mechanisms and can be modeled as a Semi-Markov Modulated Process. To verify our suggestion and model, we analyzed a total of 1,619,934 records of library visitations (including undergraduate and graduate students). It is found that the distribution of visitation intervals is well fitted with three sections of lines instead of the traditional power law distribution in log-log scale. The results confirm that some human behaviors cannot be simply expressed as power law or any other simple functions. At the same time, we divided the data into groups and extracted period bursty events. Through careful analysis in different groups, we drew a conclusion that aggregate behavior might be composed of heterogeneous behaviors, and even the behaviors of the same type tended to be different in different period. The aggregate behavior is supposed to be formed by "heterogeneous groups". We performed a series of experiments. Simulation results showed that we just needed to set up two states Semi-Markov Modulated Process to construct proper representation of heterogeneous behavior.

  10. Utilization of Professional Mental Health Services Related to Population-Level Screening for Anxiety, Depression, and Post-traumatic Stress Disorder Among Public High School Students.

    PubMed

    Prochaska, John D; Le, Vi Donna; Baillargeon, Jacques; Temple, Jeff R

    2016-08-01

    This study examines results from three mental health screening measures in a cohort of adolescent public school students in seven public schools in Southeast Texas affiliated with the Dating it Safe study. We estimated the odds of receiving professional mental health treatment in the previous year given results from different mental health screening batteries: the CES-D 10 battery for depression screening, the Screen for Child Anxiety Related Disorders, and the Primary Care Posttraumatic Stress Disorder screen. Overall, students with higher scores on screening instruments for depression, posttraumatic stress disorder, and combinations of screening instruments were more likely to have sought past-year professional mental health treatment than non-symptomatic youth. However, the proportion of students screening positive and receiving professional treatment was low, ranging from 11 to 16 %. This study emphasizes the need for broader evaluation of population-based mental health screening among adolescents. PMID:26733335

  11. Body Composition, Fitness Status, and Health Behaviors Upon Entering College: An Examination of Female College Students From Diverse Populations

    PubMed Central

    Price, Amanda A.; Whitt-Glover, Melicia C.; Kraus, Caroline L.; McKenzie, Michael J.

    2016-01-01

    Although poor health-related behaviors that impact development of chronic diseases begin much earlier than when actual disease is evident, few studies have examined health behaviors in college students, who may be at an important transitional period where early intervention could prevent development of chronic diseases. The purpose of this study was to examine health-related factors in female college students (N = 61) by race/ethnicity and weight status. We found significant differences in health profiles between non-Hispanic White (White) and African American students, including greater physical fitness and healthier diets among White students. Overweight/obese students had worse health profiles than healthy BMI students. Furthermore, weight status was significantly associated with cardiovascular fitness. This supports a focus on PA promotion for interventions in the period of emerging adulthood, alongside the other healthy behaviors, to elicit improvements in weight status and potential reduction of chronic disease risks. PMID:27279760

  12. Patterns of Emphysema Heterogeneity

    PubMed Central

    Valipour, Arschang; Shah, Pallav L.; Gesierich, Wolfgang; Eberhardt, Ralf; Snell, Greg; Strange, Charlie; Barry, Robert; Gupta, Avina; Henne, Erik; Bandyopadhyay, Sourish; Raffy, Philippe; Yin, Youbing; Tschirren, Juerg; Herth, Felix J.F.

    2016-01-01

    Background Although lobar patterns of emphysema heterogeneity are indicative of optimal target sites for lung volume reduction (LVR) strategies, the presence of segmental, or sublobar, heterogeneity is often underappreciated. Objective The aim of this study was to understand lobar and segmental patterns of emphysema heterogeneity, which may more precisely indicate optimal target sites for LVR procedures. Methods Patterns of emphysema heterogeneity were evaluated in a representative cohort of 150 severe (GOLD stage III/IV) chronic obstructive pulmonary disease (COPD) patients from the COPDGene study. High-resolution computerized tomography analysis software was used to measure tissue destruction throughout the lungs to compute heterogeneity (≥ 15% difference in tissue destruction) between (inter-) and within (intra-) lobes for each patient. Emphysema tissue destruction was characterized segmentally to define patterns of heterogeneity. Results Segmental tissue destruction revealed interlobar heterogeneity in the left lung (57%) and right lung (52%). Intralobar heterogeneity was observed in at least one lobe of all patients. No patient presented true homogeneity at a segmental level. There was true homogeneity across both lungs in 3% of the cohort when defining heterogeneity as ≥ 30% difference in tissue destruction. Conclusion Many LVR technologies for treatment of emphysema have focused on interlobar heterogeneity and target an entire lobe per procedure. Our observations suggest that a high proportion of patients with emphysema are affected by interlobar as well as intralobar heterogeneity. These findings prompt the need for a segmental approach to LVR in the majority of patients to treat only the most diseased segments and preserve healthier ones. PMID:26430783

  13. Lipid rafts: heterogeneity on the high seas.

    PubMed Central

    Pike, Linda J

    2004-01-01

    Lipid rafts are membrane microdomains that are enriched in cholesterol and glycosphingolipids. They have been implicated in processes as diverse as signal transduction, endocytosis and cholesterol trafficking. Recent evidence suggests that this diversity of function is accompanied by a diversity in the composition of lipid rafts. The rafts in cells appear to be heterogeneous both in terms of their protein and their lipid content, and can be localized to different regions of the cell. This review summarizes the data supporting the concept of heterogeneity among lipid rafts and outlines the evidence for cross-talk between raft components. Based on differences in the ways in which proteins interact with rafts, the Induced-Fit Model of Raft Heterogeneity is proposed to explain the establishment and maintenance of heterogeneity within raft populations. PMID:14662007

  14. On comparing heterogeneity across biomarkers

    PubMed Central

    Steininger, Robert J.; Rajaram, Satwik; Girard, Luc; Minna, John D.; Wu, Lani F.; Altschuler, Steven J.

    2015-01-01

    Microscopy reveals complex patterns of cellular heterogeneity that can be biologically informative. However, a limitation of microscopy is that only a small number of biomarkers can typically be monitored simultaneously. Thus, a natural question is whether additional biomarkers provide a deeper characterization of the distribution of cellular states in a population. How much information about a cell’s phenotypic state in one biomarker is gained by knowing its state in another biomarker? Here, we describe a framework for comparing phenotypic states across biomarkers. Our approach overcomes the current limitation of microscopy by not requiring co-staining biomarkers on the same cells; instead we require staining of biomarkers (possibly separately) on a common collection of phenotypically diverse cell lines. We evaluate our approach on two image datasets: 33 oncogenically diverse lung cancer cell lines stained with 7 biomarkers, and 49 less diverse subclones of one lung cancer cell line stained with 12 biomarkers. We first validate our method by comparing it to the “gold standard” of co-staining. We then apply our approach to all pairs of biomarkers and use it to identify biomarkers that yield similar patterns of heterogeneity. The results presented in this work suggest that many biomarkers provide redundant information about heterogeneity. Thus, our approach provides a practical guide for selecting independently informative biomarkers and, more generally, will yield insights into both the connectivity of biological networks and the complexity of the state space of biological systems. PMID:25425168

  15. Teaching about Population Growth.

    ERIC Educational Resources Information Center

    Otero, George G., Jr., Comp.

    This teaching guide contains 20 activities on population growth for students in grades 6-12. The purpose is to help students gain the skills, knowledge, and understanding of population dynamics so that they can make rational decisions and take responsible action regarding population matters and public policy. Activities are organized around the…

  16. Assessment of Cognitive Ability of Students with Severe and Low-Incidence Disabilities--Part 1

    ERIC Educational Resources Information Center

    Crepeau-Hobson, Franci; Vujeva, Hana

    2012-01-01

    Students with severe and low-incidence disabilities comprise a heterogeneous population that often presents a challenge to the professionals charged with evaluating their skills and abilities. This is especially true in conducting a valid assessment of the cognitive ability of these children. Often, school psychologists are limited to the use of…

  17. Characteristics and Predictors of Health Problems from Use among High-Frequency Cannabis Users in a Canadian University Student Population

    ERIC Educational Resources Information Center

    Fischer, Benedikt; Dawe, Meghan; Mcguire, Fraser; Shuper, Paul A; Jones, Wayne; Rudzinski, Katherine; Rehm, Jurgen

    2012-01-01

    Aims: Assess key cannabis use, risk and outcome characteristics among high-frequency cannabis users within a university student sample in Toronto, Canada. Methods: N = 134 active universities students (ages of 18-28) using cannabis at least three times per week were recruited by mass advertisement, telephone-screened and anonymously assessed by an…

  18. An Administrative Concern: Science Teachers' Instructional Efficacy Beliefs regarding Racially, Culturally, Economically, and Linguistically Diverse Student Populations

    ERIC Educational Resources Information Center

    Tuck Bonner, Natalie Christine

    2009-01-01

    A teacher's sense of {instructional} efficacy has been considered a critical variable in student academic performance. Researchers Tschannen-Moran and Hoy Woolfolk (2001, p.783) defined teachers' {instructional} efficacy as a teacher's judgment of his or her capabilities to bring about desired outcomes of student engagement and learning, even…

  19. Financing the Future: Postsecondary Students, Costs, and Financial Aid, 1993-1994. Household Economic Studies. Current Population Reports.

    ERIC Educational Resources Information Center

    Day, Jennifer Cheeseman; Witkowski, Kristine

    This report uses data collected in the Survey of Income and Program Participation (SIPP) to examine the characteristics of postsecondary education students, their schooling costs, and avenues of financing education for the academic year 1993-1994. The SIPP provides information on all students who were enrolled at any time, for any duration, during…

  20. Are Student Veterans a Traditional, Nontraditional, or Special Population? A Study of Veterans on the Auburn University Campus

    ERIC Educational Resources Information Center

    Pattillo, Stephen Prescott

    2011-01-01

    This non-experimental study used, with the Educational Testing Service's permission, an updated 1946 Student Opinion Questionnaire (originally designed to compare WWII veterans and nonveterans) to collect data regarding student backgrounds, attitudes and motives, worries and concerns, use of time, and perceptions of respect concerning nonveterans,…

  1. Adaptation Driven by Spatial Heterogeneities

    NASA Astrophysics Data System (ADS)

    Hermsen, Rutger

    2011-03-01

    Biological evolution and ecology are intimately linked, because the reproductive success or ``fitness'' of an organism depends crucially on its ecosystem. Yet, most models of evolution (or population genetics) consider homogeneous, fixed-size populations subjected to a constant selection pressure. To move one step beyond such ``mean field'' descriptions, we discuss stochastic models of evolution driven by spatial heterogeneity. We imagine a population whose range is limited by a spatially varying environmental parameter, such as a temperature or the concentration of an antibiotic drug. Individuals in the population replicate, die and migrate stochastically. Also, by mutation, they can adapt to the environmental stress and expand their range. This way, adaptation and niche expansion go hand in hand. This mode of evolution is qualitatively different from the usual notion of a population climbing a fitness gradient. We analytically calculate the rate of adaptation by solving a first passage time problem. Interestingly, the joint effects of reproduction, death, mutation and migration result in two distinct parameter regimes depending on the relative time scales of mutation and migration. We argue that the proposed scenario may be relevant for the rapid evolution of antibiotic resistance. This work was supported by the Center for Theoretical Biological Physics sponsored by the National Science Foundation (NSF) (Grant PHY-0822283).

  2. Modeling blood flow heterogeneity.

    PubMed

    King, R B; Raymond, G M; Bassingthwaighte, J B

    1996-01-01

    It has been known for some time that regional blood flows within an organ are not uniform. Useful measures of heterogeneity of regional blood flows are the standard deviation and coefficient of variation or relative dispersion of the probability density function (PDF) of regional flows obtained from the regional concentrations of tracers that are deposited in proportion to blood flow. When a mathematical model is used to analyze dilution curves after tracer solute administration, for many solutes it is important to account for flow heterogeneity and the wide range of transit times through multiple pathways in parallel. Failure to do so leads to bias in the estimates of volumes of distribution and membrane conductances. Since in practice the number of paths used should be relatively small, the analysis is sensitive to the choice of the individual elements used to approximate the distribution of flows or transit times. Presented here is a method for modeling heterogeneous flow through an organ using a scheme that covers both the high flow and long transit time extremes of the flow distribution. With this method, numerical experiments are performed to determine the errors made in estimating parameters when flow heterogeneity is ignored, in both the absence and presence of noise. The magnitude of the errors in the estimates depends upon the system parameters, the amount of flow heterogeneity present, and whether the shape of the input function is known. In some cases, some parameters may be estimated to within 10% when heterogeneity is ignored (homogeneous model), but errors of 15-20% may result, even when the level of heterogeneity is modest. In repeated trials in the presence of 5% noise, the mean of the estimates was always closer to the true value with the heterogeneous model than when heterogeneity was ignored, but the distributions of the estimates from the homogeneous and heterogeneous models overlapped for some parameters when outflow dilution curves were

  3. A Comparison of a Sub-Population of Santa Monica College Students to Other Community College Students in the Southern California Area: An Analysis of the Results from the Community College Student Experiences Questionnaire.

    ERIC Educational Resources Information Center

    Ackermann, Susan P.

    Drawing from a nationwide pilot test of the Community College Student Experiences Questionnaire (CCSEQ), a study was conducted to compare Santa Monica College (SMC) students (N=106) with students attending nine other Southern California community colleges (N=498). The CCSEQ was designed to provide information on the relationship between students'…

  4. Heterogeneity of FFA responses or multiplexing?

    PubMed Central

    Ross, David A.; McGugin, Rankin W.; Gauthier, Isabel

    2014-01-01

    Recent work using cluster analysis of brain activity during movies revealed distinct clusters that respond to faces and different non-face categories in the fusiform face area (FFA). Because of the limited heterogeneity observed, these results could mean that FFA contains one population of cells capable of representing multiple categories. PMID:24360882

  5. Heterogeneous Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Schryer, David R.

    In the past few years it has become increasingly clear that heterogeneous, or multiphase, processes play an important role in the atmosphere. Unfortunately the literature on the subject, although now fairly extensive, is still rather dispersed. Furthermore, much of the expertise regarding heterogeneous processes lies in fields not directly related to atmospheric science. Therefore, it seemed desirable to bring together for an exchange of ideas, information, and methodologies the various atmospheric scientists who are actively studying heterogeneous processes as well as other researchers studying similar processes in the context of other fields.

  6. [Prevalence of migraine in the medical student population as determined by means of the 'Alcoi 1992' questionnaire].

    PubMed

    Muñiz, R; Macía, C; Montiel, I; González, O; Martín, R; Asensio, M; Matías-Guiu, J

    1995-01-01

    A group of medical students were interviewed using the 'Alcoi 1992' questionnaire based on the diagnostic criteria of the International Headache Society (IHS) in order to assess the prevalence and various characteristics of migraine. This questionnaire for headache diagnosis was approved in 1993, showing both high sensitivity and exactness in diagnosing migraine. Sensitivity, exactness, predictive value and agreement index of the questionnaire in migraine diagnosis were 100%, 94%, 90% (positive) or 100% (negative) and 0.71% respectively. The group was made up of 96 students of both sexes, with an average age of 23.3 years (standard deviation 1.87). A total of 92 students, 35 male and 57 female, reported headaches. The total prevalence rate for headache was 95.8%, the reliability interval (RI) being 76.7-114.9. In the case of female students, the prevalence rate for headache was 96.6% (RI 71.7-121.5) and in the case of male students it was 94.6% (RI 63-125.7). A total of 20 students, six male and 14 female, fulfilled the criteria for migraine. The overall prevalence rate for migraine was 20.8% (RI 11.9-29.7), the prevalence for females being 23.7% (RI 11.6-35.8) and that for males 16.2% (RI 3.7-28.7). The questionnaire would appear to be a useful, rapid and simple method in the assessment of migraine diagnostic. PMID:7497254

  7. Teaching Heterogeneous Classes.

    ERIC Educational Resources Information Center

    Millrood, Radislav

    2002-01-01

    Discusses an approach to teaching heterogeneous English-as-a-Second/Foreign-Language classes. Draws on classroom research data to describe the features of a success-building lesson context. (Author/VWL)

  8. Heterogeneous atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Schryer, D. R.

    1982-01-01

    The present conference on heterogeneous atmospheric chemistry considers such topics concerning clusters, particles and microparticles as common problems in nucleation and growth, chemical kinetics, and catalysis, chemical reactions with aerosols, electron beam studies of natural and anthropogenic microparticles, and structural studies employing molecular beam techniques, as well as such gas-solid interaction topics as photoassisted reactions, catalyzed photolysis, and heterogeneous catalysis. Also discussed are sulfur dioxide absorption, oxidation, and oxidation inhibition in falling drops, sulfur dioxide/water equilibria, the evidence for heterogeneous catalysis in the atmosphere, the importance of heterogeneous processes to tropospheric chemistry, soot-catalyzed atmospheric reactions, and the concentrations and mechanisms of formation of sulfate in the atmospheric boundary layer.

  9. Towards heterogeneous distributed debugging

    SciTech Connect

    Damodaran-Kamal, S.K.

    1995-04-01

    Several years of research and development in parallel debugger design have given up several techniques, though implemented in a wide range of tools for an equally wide range of systems. This paper is an evaluation of these myriad techniques as applied to the design of a heterogeneous distributed debugger. The evaluation is based on what features users perceive as useful, as well as the ease of implementation of the features using the available technology. A preliminary architecture for such a heterogeneous tool is proposed. Our effort in this paper is significantly different from the other efforts at creating portable and heterogeneous distributed debuggers in that we concentrate on support for all the important issues in parallel debugging, instead of simply concentrating on portability and heterogeneity.

  10. Welcoming Blue-Collar Scholars into the Ivory Tower: Developing Class-Conscious Strategies for Student Success. Series on Special Student Populations

    ERIC Educational Resources Information Center

    Soria, Krista M.

    2015-01-01

    "Welcoming Blue-Collar Scholars Into the Ivory Tower" is the first volume in a new book series designed to explore how institutional policies, practices, and cultures shape learning, development, and success for students who have been historically underserved or given limited consideration in the design of higher education contexts.…

  11. Developing Dental Students' Awareness of Health Care Disparities and Desire to Serve Vulnerable Populations Through Service-Learning.

    PubMed

    Behar-Horenstein, Linda S; Feng, Xiaoying; Roberts, Kellie W; Gibbs, Micaela; Catalanotto, Frank A; Hudson-Vassell, Charisse M

    2015-10-01

    Service-learning in dental education helps students integrate knowledge with practice in an underserved community setting. The aim of this study was to explore how a service-learning experience affected a small group of dental students' beliefs about cultural competence, professionalism, career development, desire to practice in a community service setting, and perceptions about access and disparities issues. Prior to beginning their first year of dental school, five first-year dental students at one U.S. dental school participated in a six-week service-learning program in which they interned at one of three at-risk settings in order to experience health care delivery there. After the program, 60 reflective writing assignments completed by the participants were analyzed using grounded theory methods; interviews with the students were used to corroborate the findings from that analysis. Seven themes identified in the journal reflections and interview findings showed enhanced awareness of social health care issues and patient differences, as well as a social justice orientation and desire to address disparities. Building on this study, future research should explore the curricular components of service-learning programs to ensure students receive ample opportunity to reflect upon their experiences in order to integrate previously held assumptions with their newfound knowledge. PMID:26427778

  12. Characterization of Paper Heterogeneity

    NASA Astrophysics Data System (ADS)

    Considine, John M.

    Paper and paperboard are the most widely-used green materials in the world because they are renewable, recyclable, reusable, and compostable. Continued and expanded use of these materials and their potential use in new products requires a comprehensive understanding of the variability of their mechanical properties. This work develops new methods to characterize the mechanical properties of heterogeneous materials through a combination of techniques in experimental mechanics, materials science and numerical analysis. Current methods to analyze heterogeneous materials focus on crystalline materials or polymer-crystalline composites, where material boundaries are usually distinct. This work creates a methodology to analyze small, continuously-varying stiffness gradients in 100% polymer systems and is especially relevant to paper materials where factors influencing heterogeneity include local mass, fiber orientation, individual pulp fiber properties, local density, and drying restraint. A unique approach was used to understand the effect of heterogeneity on paper tensile strength. Additional variation was intentionally introduced, in the form of different size holes, and their effect on strength was measured. By modifying two strength criteria, an estimate of strength in the absence of heterogeneity was determined. In order to characterize stiffness heterogeneity, a novel load fixture was developed to excite full-field normal and shear strains for anisotropic stiffness determination. Surface strains were measured with digital image correlation and were analyzed with the VFM (Virtual Fields Method). This approach led to VFM-identified stiffnesses that were similar to values determined by conventional tests. The load fixture and VFM analyses were used to measure local stiffness and local stiffness variation on heterogeneous anisotropic materials. The approach was validated on simulated heterogeneous materials and was applied experimentally to three different paperboards

  13. Establishing the reliability and validity of the Zagazig Depression Scale in a UK student population: an online pilot study

    PubMed Central

    2010-01-01

    Background It is thought that depressive disorders will be the second leading cause of disability worldwide by 2020. Recently, there is a steady increase in the number of university students diagnosed and treated as depression patients. It can be assumed that depression is a serious mental health problem for university students because it affects all age groups of the students either younger or older equally. The current study aims to establish the reliability and validity of the Zagazig Depression scale in a UK sample. Methods The study was a cross-sectional online survey. A sample of 133 out of 275 undergraduate students from a range of UK Universities in the academic year 2008-2009, aged 20.3 ± 6.3 years old were recruited. A modified back translated version of Zagazig Depression scale was used. In order to validate the Zagazig Depression scale, participants were asked to complete the Patient Health Questionnaire. Statistical analysis includes Kappa analysis, Cronbach's alpha, Spearman's correlation analysis, and Confirmatory Factor analysis. Results Using the recommended cut-off of Zagazig Depression scale for possible minor depression it was found that 30.3% of the students have depression and higher percentage was identified according to the Patient Health Questionnaire (37.4%). Females were more depressed. The mean ZDS score was 8.3 ± 4.2. Rates of depression increase as students get older. The reliability of The ZDS was satisfactory (Cronbach's alpha was .894). For validity, ZDS score was strongly associated with PHQ, with no significant difference (p-value > 0.05), with strong positive correlation (r = +.8, p-value < 0.01). Conclusion The strong, significant correlation between the PHQ and ZDS, along with high internal consistency of the ZDS as a whole provides evidence that ZDS is a reliable measure of depressive symptoms and is promising for the use of the translated ZDS in a large-scale cross-culture study. PMID:21143972

  14. A collaborative clinical and population-based curriculum for medical students to address primary care needs of the homeless in New York City shelters : Teaching homeless healthcare to medical students.

    PubMed

    Asgary, Ramin; Naderi, Ramesh; Gaughran, Margaret; Sckell, Blanca

    2016-06-01

    Background Millions of Americans experience homelessness annually. Medical providers do not receive adequate training in primary care of the homeless.Methods Starting in 2012, a comprehensive curriculum was offered to medical students during their family medicine or ambulatory clerkship, covering clinical, social and advocacy, population-based, and policy aspects. Students were taught to: elicit specific social history, explore health expectations, and assess barriers to healthcare; evaluate clinical conditions specific to the homeless and develop plans for care tailored toward patients' medical and social needs; collaborate with shelter staff and community organizations to improve disease management and engage in advocacy efforts. A mixed methods design was used to evaluate students' knowledge, attitudes, and skills including pre- and post-curriculum surveys, debriefing sessions, and observed clinical skills.Results The mean age of the students (n = 30) was 26.5 years; 55 % were female. The overall scores improved significantly in knowledge, attitude, and self-efficacy domains using paired t‑test (p < 0.01). Specific skills in evaluating mental health, substance abuse, and risky behaviours improved significantly (p < 0.05). In evaluation of communication skills, the majority were rated as having 'outstanding rapport with patients.'Conclusions Comprehensive and ongoing clinical component in shelter clinics, complementary teaching, experienced faculty, and working relationship and collaboration with community organizations were key elements. PMID:27277430

  15. Use of Trans Fat Information on Food Labels and Its Determinants in a Multiethnic College Student Population

    ERIC Educational Resources Information Center

    Jasti, Sunitha; Kovacs, Szilvia

    2010-01-01

    Objectives: To examine the correlates of trans fat knowledge and trans fat label use; to examine the influence of trans fat knowledge, trans fat label use, and dietary attitudes on intake of high trans fat food. Design: Cross-sectional survey. Setting: An urban commuter college. Subjects: Two hundred twenty-two college students. Variables…

  16. The Paradoxes of Freedom: A Thematic Approach to Teaching a Compulsory Composition Course to a Multi-Ethnic Student Population.

    ERIC Educational Resources Information Center

    Lynch, Daniel J.

    A composition teacher at a New York City community college where cooperative education is stressed found that focusing the writing of his multiethnic students on the theme of freedom helped them look at their lives differently, revealing the contradictions involved in their beliefs, ideals, and prejudices. The course began with a discussion of…

  17. An Examination of the Substance Abuse Subtle Screening Inventory-3 Correctional Scale in a College Student Population

    ERIC Educational Resources Information Center

    Burck, Andrew M.; Laux, John M.; Ritchie, Martin; Baker, David

    2008-01-01

    In this study, the authors examined the Substance Abuse Subtle Screening Inventory-3 Correctional scale's sensitivity and specificity at detecting college students' illegal behaviors. Sensitivity was strong, but specificity was weak. Implications for counseling and suggestions for future research are included. (Contains 3 tables.)

  18. The Impact of Rapid Automatized Naming and Phonological Awareness on the Reading Fluency of a Minority Student Population

    ERIC Educational Resources Information Center

    Taub, Gordon E.; Szente, Judit

    2012-01-01

    The purpose of this study was to explore the relationship between phonological awareness (PA) and rapid automatized naming (RAN) on the reading fluency (RF) of students from traditionally underrepresented groups. The study included 86 participants attending 1st through 4th grade within an inner-city charter school located in a high-poverty, urban…

  19. The Use of Conceptual versus Physical Models in Teaching Action Research to Culturally Diverse Student Populations: A Preliminary Analysis.

    ERIC Educational Resources Information Center

    McMurray, Adela J.

    2002-01-01

    Graduate business administration students (n=55) were asked which model they used for action research projects: conceptual or a physical model visually depicting action research. The physical model was favored by 69%; most agreed that it helped them understand the process of action research, was easy to use, and flexibly applied to various…

  20. E-Service-Learning: The Evolution of Service-Learning to Engage a Growing Online Student Population

    ERIC Educational Resources Information Center

    Waldner, Leora S.; McGorry, Sue Y.; Widener, Murray C.

    2012-01-01

    E-service-learning (electronic service-learning)--online course instruction and/or service--holds massive potential to transform both service-learning and online learning by freeing service-learning from geographical constraints and by equipping online learning with a powerful and much-needed tool to promote engagement. Students are increasingly…

  1. Update of Project to Introduce Technology in Urban Schools Which Have Low Achievement and Economically Poor Student Populations

    ERIC Educational Resources Information Center

    Smith, Gary R.

    2009-01-01

    This document provides new insights into events which occurred in a project funded by a Technology Literacy Challenge Fund grant awarded by Michigan Department of Education(MDE) in 2000. One purpose of this document is to update the formal report of the project which introduced new technology for use by low achieving students who are studying in…

  2. Do Your Homework! Investigating the Role of Culturally Relevant Pedagogy in Comprehensive School Reform Models Serving Diverse Student Populations

    ERIC Educational Resources Information Center

    Durden, Tonia

    2008-01-01

    Like the African proverb, "It takes a village to raise a child", many educational researchers charge that it takes a comprehensive school reform to raise student achievement. With the passing of the No Child Left Behind legislation in 2002, national officials authorized the Comprehensive School Reform program to support low performing schools as…

  3. Preparing Elementary Pre-Service Teachers from a Non-Traditional Student Population to Teach with Technology

    ERIC Educational Resources Information Center

    An, Heejung; Wilder, Hilary; Lim, Keol

    2011-01-01

    This article documents the development of a two-stage curriculum intended to improve elementary teacher candidates' understanding of technology integration. Most students in the program came from low-income districts and lacked technology experience. The first stage of the curriculum consisted of a prerequisite basic technology skills course…

  4. On the Relationship between Autistic Traits and Executive Functioning in a Non-Clinical Dutch Student Population

    ERIC Educational Resources Information Center

    Maes, Joseph HR; Vissers, Constance ThWM; Egger, Jos IM; Eling, Paul ATM

    2013-01-01

    We examined the association between autistic traits and different aspects of executive functioning (EF), using non-clinical Social Science and Science students as participants. Autistic traits, and associated personality traits, were measured using the Autism Quotient (AQ) and the Temperament and Character Inventory (TCI), respectively. EF was…

  5. The Relationship between Wait Time after Triage and Show Rate for Intake in a Nonurgent Student Population

    ERIC Educational Resources Information Center

    DiMino, John; Blau, Gary

    2012-01-01

    Ideally, students requesting services should be seen quickly at their university counseling center to increase the likelihood of a successful treatment outcome. However, in these times of ever-increasing demand for university counseling services and the challenges of securing resources to keep up with that demand, the reality of prompt…

  6. Spatially correlated heterogeneous aspirations to enhance network reciprocity

    NASA Astrophysics Data System (ADS)

    Tanimoto, Jun; Nakata, Makoto; Hagishima, Aya; Ikegaya, Naoki

    2012-02-01

    Perc & Wang demonstrated that aspiring to be the fittest under conditions of pairwise strategy updating enhances network reciprocity in structured populations playing 2×2 Prisoner's Dilemma games (Z. Wang, M. Perc, Aspiring to the fittest and promoted of cooperation in the Prisoner's Dilemma game, Physical Review E 82 (2010) 021115; M. Perc, Z. Wang, Heterogeneous aspiration promotes cooperation in the Prisoner's Dilemma game, PLOS one 5 (12) (2010) e15117). Through numerical simulations, this paper shows that network reciprocity is even greater if heterogeneous aspirations are imposed. We also suggest why heterogeneous aspiration fosters network reciprocity. It distributes strategy updating speed among agents in a manner that fortifies the initially allocated cooperators' clusters against invasion. This finding prompted us to further enhance the usual heterogeneous aspiration cases for heterogeneous network topologies. We find that a negative correlation between degree and aspiration level does extend cooperation among heterogeneously structured agents.

  7. Dynamical robustness of coupled heterogeneous oscillators

    NASA Astrophysics Data System (ADS)

    Tanaka, Gouhei; Morino, Kai; Daido, Hiroaki; Aihara, Kazuyuki

    2014-05-01

    We study tolerance of dynamic behavior in networks of coupled heterogeneous oscillators to deterioration of the individual oscillator components. As the deterioration proceeds with reduction in dynamic behavior of the oscillators, an order parameter evaluating the level of global oscillation decreases and then vanishes at a certain critical point. We present a method to analytically derive a general formula for this critical point and an approximate formula for the order parameter in the vicinity of the critical point in networks of coupled Stuart-Landau oscillators. Using the critical point as a measure for dynamical robustness of oscillator networks, we show that the more heterogeneous the oscillator components are, the more robust the oscillatory behavior of the network is to the component deterioration. This property is confirmed also in networks of Morris-Lecar neuron models coupled through electrical synapses. Our approach could provide a useful framework for theoretically understanding the role of population heterogeneity in robustness of biological networks.

  8. Managing Power Heterogeneity

    NASA Astrophysics Data System (ADS)

    Pruhs, Kirk

    A particularly important emergent technology is heterogeneous processors (or cores), which many computer architects believe will be the dominant architectural design in the future. The main advantage of a heterogeneous architecture, relative to an architecture of identical processors, is that it allows for the inclusion of processors whose design is specialized for particular types of jobs, and for jobs to be assigned to a processor best suited for that job. Most notably, it is envisioned that these heterogeneous architectures will consist of a small number of high-power high-performance processors for critical jobs, and a larger number of lower-power lower-performance processors for less critical jobs. Naturally, the lower-power processors would be more energy efficient in terms of the computation performed per unit of energy expended, and would generate less heat per unit of computation. For a given area and power budget, heterogeneous designs can give significantly better performance for standard workloads. Moreover, even processors that were designed to be homogeneous, are increasingly likely to be heterogeneous at run time: the dominant underlying cause is the increasing variability in the fabrication process as the feature size is scaled down (although run time faults will also play a role). Since manufacturing yields would be unacceptably low if every processor/core was required to be perfect, and since there would be significant performance loss from derating the entire chip to the functioning of the least functional processor (which is what would be required in order to attain processor homogeneity), some processor heterogeneity seems inevitable in chips with many processors/cores.

  9. The Community College Effect Revisited: The Importance of Attending to Heterogeneity and Complex Counterfactuals*

    PubMed Central

    Brand, Jennie E.; Pfeffer, Fabian T.; Goldrick-Rab, Sara

    2015-01-01

    Community colleges are controversial educational institutions, often said to simultaneously expand college opportunities and diminish baccalaureate attainment. We assess the seemingly contradictory functions of community colleges by attending to effect heterogeneity and to alternative counterfactual conditions. Using data on postsecondary outcomes of high school graduates of Chicago Public Schools, we find that enrolling at a community college penalizes more advantaged students who otherwise would have attended four-year colleges, particularly highly selective schools; however, these students represent a relatively small portion of the community college population, and these estimates are almost certainly biased. On the other hand, enrolling at a community college has a modest positive effect on bachelor's degree completion for disadvantaged students who otherwise would not have attended college; these students represent the majority of community college goers. We conclude that discussions among scholars, policymakers, and practitioners should move beyond considering the pros and cons of community college attendance for students in general to attending to the implications of community college attendance for targeted groups of students. PMID:25825705

  10. Vibrational resonance in a heterogeneous scale free network of neurons

    NASA Astrophysics Data System (ADS)

    Uzuntarla, Muhammet; Yilmaz, Ergin; Wagemakers, Alexandre; Ozer, Mahmut

    2015-05-01

    Vibrational resonance (VR) is a phenomenon whereby the response of some dynamical systems to a weak low-frequency signal can be maximized with the assistance of an optimal intensity of another high-frequency signal. In this paper, we study the VR in a heterogeneous neural system having a complex network topology. We consider a scale-free network of neurons where the heterogeneity is in the intrinsic excitability of the individual neurons. It is shown that emergence of VR in heterogeneous neuron population requires less energy than a homogeneous population. We also find that electrical coupling strength among neurons plays a key role in determining the weak signal processing capacity of the heterogeneous population. Lastly, we investigate the influence of interneuronal link density on the VR and demonstrate that the energy needed to obtain the resonance grows with the increase in average degree.

  11. An administrative concern: Science teachers' instructional efficacy beliefs regarding racially, culturally, economically, and linguistically diverse student populations

    NASA Astrophysics Data System (ADS)

    Tuck Bonner, Natalie Christine

    A teacher's sense of {instructional} efficacy has been considered a critical variable in student academic performance. Researchers Tschannen-Moran and Hoy Woolfolk (2001, p.783) defined teachers' {instructional} efficacy as a teacher's judgment of his or her capabilities to bring about desired outcomes of student engagement and learning, even among those students who may be difficult or unmotivated. There has been a substantial amount of research which reveals a strong correlation among teacher efficacy, teaching performance, and student achievement (Goddard & Goddard, et.al., 2000; Hackett; Hackett, 1995; Pajares, 1997 as cited in Villereal, 2005). This research study explored the content area of science and teacher's personal perception of their competency level in teaching science to all learners regardless of socio-economic, ethnicity/race or gender for grade levels Pre-K to 12. Lewthwaite states that a science teacher's personal teacher attributes or intrinsic factors such as science teaching self-efficacy, professional science knowledge, science teaching, instructional methodologies, interest in science, and motivation to teach science are critical dimensions and noted barriers in the delivery of science programs on elementary level campuses (Lewthwaite, Stableford & Fisher, 2001). This study focused on teacher instructional efficacy issues which may affect diverse learners' classroom and state-mandated assessment academic performance outcomes. A SPSS analysis of data was obtained from the following teacher survey instruments: The Bandura Teacher Efficacy Scale, the SEBEST, and the SETAKIST. Research findings revealed that a majority of science teachers surveyed believe they can effectively teach learners of diverse backgrounds, but responded with a sense of lower efficaciousness in teaching English Language Learners. There was also a statistically significant difference found between a state science organization and a national science organization

  12. A Statistical Portrait of the Multicultural/Multiethnic Student Population in Portland Public Schools. 1986-87.

    ERIC Educational Resources Information Center

    Portland Public Schools, OR. Research and Evaluation Dept.

    This second annual consolidated report of key statistics covers the status of culturally diverse children in the Portland (Oregon) School District during the 1986-87 school year. The district enrollment by ethnic group as of October 1, 1986, included 37,907 White, 7,913 Black, 3,881 Asian, 1,111 Hispanic, and 1,068 American Indian students, with a…

  13. Junior Biology, Populations.

    ERIC Educational Resources Information Center

    Hamilton City Board of Education (Ontario).

    Twenty-one studies related to populations are included in this student manual for a junior high school biology course. Each activity or study provides questions, diagrams, experiments, and/or descriptive material to which the student must respond. Population studies pertain to individual plants and animals, their physical environments, reactions…

  14. On the origin of sperm epigenetic heterogeneity.

    PubMed

    Laurentino, Sandra; Borgmann, Jennifer; Gromoll, Jörg

    2016-05-01

    The influence of epigenetic modifications on reproduction and on the function of male germ cells has been thoroughly demonstrated. In particular, aberrant DNA methylation levels in sperm have been associated with abnormal sperm parameters, lower fertilization rates and impaired embryo development. Recent reports have indicated that human sperm might be epigenetically heterogeneous and that abnormal DNA methylation levels found in the sperm of infertile men could be due to the presence of sperm populations with different epigenetic quality. However, the origin and the contribution of different germ cell types to this suspected heterogeneity remain unclear. In this review, we focus on sperm epigenetics at the DNA methylation level and its importance in reproduction. We take into account the latest developments and hypotheses concerning the functional significance of epigenetic heterogeneity coming from the field of stem cell and cancer biology and discuss the potential importance and consequences of sperm epigenetic heterogeneity for reproduction, male (in)fertility and assisted reproductive technologies (ART). Based on the current information, we propose a model in which spermatogonial stem cell variability, either intrinsic or due to external factors (such as endocrine action and environmental stimuli), can lead to epigenetic sperm heterogeneity, sperm epimutations and male infertility. The elucidation of the precise causes for epimutations, the conception of adequate therapeutic options and the development of sperm selection technologies based on epigenetic quality should be regarded as crucial to the improvement of ART outcome in the near future. PMID:26884419

  15. Evaluating foam heterogeneity

    NASA Technical Reports Server (NTRS)

    Liou, D. W.; Lee, W. M.

    1972-01-01

    New analytical tool is available to calculate the degree of foam heterogeneity based on the measurement of gas diffusivity values. Diffusion characteristics of plastic foam are described by a system of differential equations based on conventional diffusion theory. This approach saves research and computation time in studying mass or heat diffusion problems.

  16. Heterogeneous waste processing

    DOEpatents

    Vanderberg, Laura A.; Sauer, Nancy N.; Brainard, James R.; Foreman, Trudi M.; Hanners, John L.

    2000-01-01

    A combination of treatment methods are provided for treatment of heterogeneous waste including: (1) treatment for any organic compounds present; (2) removal of metals from the waste; and, (3) bulk volume reduction, with at least two of the three treatment methods employed and all three treatment methods emplyed where suitable.

  17. Modeling vaccination in a heterogeneous metapopulation system

    NASA Astrophysics Data System (ADS)

    Lachiany, Menachem

    2016-09-01

    We present here a multicity SIS epidemic model with vaccination. The model describes the dynamics of heterogeneous metapopulations that contain imperfectly vaccinated individuals. The effect of vaccination on heterogeneous multicity models has not been previously studied. We show that under very generic conditions, the epidemic threshold does not depend on the diffusion coefficient of the vaccinated individuals, but it does depend on the diffusion coefficient of the infected population. We then show, using a novel methodology, that the reproduction number is determined by the homogeneous model parameters and by the maximal number of neighbors a city can have, when the diffusion coefficient of the infected population is low. Finally, we present numerical simulations to support the analytical results.

  18. Sparse covariance estimation in heterogeneous samples*

    PubMed Central

    Rodríguez, Abel; Lenkoski, Alex; Dobra, Adrian

    2015-01-01

    Standard Gaussian graphical models implicitly assume that the conditional independence among variables is common to all observations in the sample. However, in practice, observations are usually collected from heterogeneous populations where such an assumption is not satisfied, leading in turn to nonlinear relationships among variables. To address such situations we explore mixtures of Gaussian graphical models; in particular, we consider both infinite mixtures and infinite hidden Markov models where the emission distributions correspond to Gaussian graphical models. Such models allow us to divide a heterogeneous population into homogenous groups, with each cluster having its own conditional independence structure. As an illustration, we study the trends in foreign exchange rate fluctuations in the pre-Euro era. PMID:26925189

  19. Extreme late chronotypes and social jetlag challenged by Antarctic conditions in a population of university students from Uruguay

    PubMed Central

    Tassino, Bettina; Horta, Stefany; Santana, Noelia; Levandovski, Rosa; Silva, Ana

    2016-01-01

    In humans, a person’s chronotype depends on environmental cues and on individual characteristics, with late chronotypes prevailing in youth. Social jetlag (SJL), the misalignment between an individual׳s biological clock and social time, is higher in late chronotypes. Strong SJL is expected in Uruguayan university students with morning class schedules and very late entertainment activities. Sleep disorders have been reported in Antarctic inhabitants, that might be a response to the extreme environment or to the strictness of Antarctic life. We evaluated, for the first time in Uruguay, the chronotypes and SJL of 17 undergraduate students of the First Uruguayan Summer School on Antarctic Research, using Munich Chronotype Questionnaire (MCTQ) and sleep logs (SL) recorded during 3 phases: pre-Antarctic, Antarctic, and post-Antarctic. The midsleep point of free days corrected for sleep debt on work days (MSFsc,) was used as proxy of individuals’ chronotype, whose values (around 6 a.m.) are the latest ever reported. We found a SJL of around 2 h in average, which correlated positively with MSFsc, confirming that late chronotypes generate a higher sleep debt during weekdays. Midsleep point and sleep duration significantly decreased between pre-Antarctic and Antarctic phases, and sleep duration rebounded to significant higher values in the post-Antarctic phase. Waking time, but not sleep onset time, significantly varied among phases. This evidence suggests that sleep schedules more likely depended on the social agenda than on the environmental light–dark shifts. High motivation of students towards Antarctic activities likely induced a subjective perception of welfare non-dependent on sleep duration. PMID:27226819

  20. Psychometric Properties of the Arabic Version of the Obsessive Compulsive Beliefs Questionnaire-44 in a Student Population

    PubMed Central

    Rahat, Maryam; Mohamadi, Norolah

    2012-01-01

    Objective We examined the psychometric properties of the Arabic version of the Obsessive Compulsive Beliefs Questionnaire-44 (OBQ-44) in a sample of Kuwait University students. This questionnaire was developed by the Obsessive Compulsive Cognitions Working Group in order to assess belief domains believed to be crucial in the development of obsessive compulsive symptoms. Method The Arabic version of the OBQ-44 was developed according to the standard translation and back-translation methods. The Arabic versions of the OBQ-44, the Maudsley Obsessive - Compulsive Inventory (MOCI), and Beck Depression Inventory-Revised (BDI-II) were then administered on a sample of 200 Kuwait University students from the faculty of humanities chosen through random cluster sampling. Retest was administered within a 4 week time period. Results The results of principle component factor analysis with varimax rotation indicated 6 factors which overlapped to a high degree. A 3 factor solution was chosen based on the scree plot and factor loadings which explained 36.12% of the variance. The factors were labeled as responsibility and threat estimation (RT), importance and control of thought (ICT) and perfectionism/Certainty (PC). The reliability coefficient of the three factors and the total score were assessed using three methods: Internal consistency, Test-retest reliability and Split-half reliability. Results showed an acceptable internal consistency for the Arabic version of the OBQ-44. Regarding the validity of OBQ-44, the instrument correlated with the total score of MOCI and most of its subscales. Conclusion These data support the reliability and validity of the OBQ-44 in a sample of Kuwait University students. PMID:23408782