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Sample records for accelerated evolutionary rate

  1. DnaK-Dependent Accelerated Evolutionary Rate in Prokaryotes.

    Kadibalban, A Samer; Bogumil, David; Landan, Giddy; Dagan, Tal

    2016-01-01

    Many proteins depend on an interaction with molecular chaperones in order to fold into a functional tertiary structure. Previous studies showed that protein interaction with the GroEL/GroES chaperonine and Hsp90 chaperone can buffer the impact of slightly deleterious mutations in the protein sequence. This capacity of GroEL/GroES to prevent protein misfolding has been shown to accelerate the evolution of its client proteins. Whether other bacterial chaperones have a similar effect on their client proteins is currently unknown. Here, we study the impact of DnaK (Hsp70) chaperone on the evolution of its client proteins. Evolutionary parameters were derived from comparison of the Escherichia coli proteome to 1,808,565 orthologous proteins in 1,149 proteobacterial genomes. Our analysis reveals a significant positive correlation between protein binding frequency with DnaK and evolutionary rate. Proteins with high binding affinity to DnaK evolve on average 4.3-fold faster than proteins in the lowest binding affinity class at the genus resolution. Differences in evolutionary rates of DnaK interactor classes are still significant after adjusting for possible effects caused by protein expression level. Furthermore, we observe an additive effect of DnaK and GroEL chaperones on the evolutionary rates of their common interactors. Finally, we found pronounced similarities in the physicochemical profiles that characterize proteins belonging to DnaK and GroEL interactomes. Our results thus implicate DnaK-mediated folding as a major component in shaping protein evolutionary dynamics in bacteria and supply further evidence for the long-term manifestation of chaperone-mediated folding on genome evolution. PMID:27189986

  2. Accelerated evolutionary rates in tropical and oceanic parmelioid lichens (Ascomycota

    Blanco Oscar

    2008-09-01

    Full Text Available Abstract Background The rate of nucleotide substitutions is not constant across the Tree of Life, and departures from a molecular clock have been commonly reported. Within parmelioid lichens, the largest group of macrolichens, large discrepancies in branch lengths between clades were found in previous studies. Using an extended taxon sampling, we test for presence of significant rate discrepancies within and between these clades and test our a priori hypothesis that such rate discrepancies may be explained by shifts in moisture regime or other environmental conditions. Results In this paper, the first statistical evidence for accelerated evolutionary rate in lichenized ascomycetes is presented. Our results give clear evidence for a faster rate of evolution in two Hypotrachyna clades that includes species occurring in tropical and oceanic habitats in comparison with clades consisting of species occurring in semi-arid and temperate habitats. Further we explore potential links between evolutionary rates and shifts in habitat by comparing alternative Ornstein-Uhlenbeck models. Conclusion Although there was only weak support for a shift at the base of a second tropical clade, where the observed nucleotide substitution rate is high, overall support for a shift in environmental conditions at cladogenesis is very strong. This suggests that speciation in some lichen clades has proceeded by dispersal into a novel environment, followed by radiation within that environment. We found moderate support for a shift in moisture regime at the base of one tropical clade and a clade occurring in semi-arid regions and a shift in minimum temperature at the base of a boreal-temperate clade.

  3. Accelerated evolutionary rate in sulfur-oxidizing endosymbiotic bacteria associated with the mode of symbiont transmission.

    Peek, A S; Vrijenhoek, R C; Gaut, B S

    1998-11-01

    The nearly neutral theory of molecular evolution predicts that the rate of nucleotide substitution should accelerate in small populations at sites under low selective constraint. We examined these predictions with respect to the relative population sizes for three bacterial life histories within chemolithoautotrophic sulfur-oxidizing bacteria: (1) free-living bacteria, (2) environmentally captured symbionts, and (3) maternally transmitted symbionts. Both relative rates of nucleotide substitution and relative ratios of loop, stem, and domain substitutions from 1,165 nt of the small-subunit 16S rDNA were consistent with expectations of the nearly neutral theory. Relative to free-living sulfur-oxidizing autotrophic bacteria, the maternally transmitted symbionts have faster substitution rates overall and also in low-constraint domains of 16S rDNA. Nucleotide substitition rates also differ between loop and stem positions. All of these findings are consistent with the predictions that these symbionts have relatively small effective population sizes. In contrast, the rates of nucleotide substitution in environmentally captured symbionts are slower, particularly in high-constraint domains, than in free-living bacteria. PMID:12572615

  4. Metabolic acceleration in animal ontogeny: An evolutionary perspective

    Kooijman, S. A. L. M.

    2014-11-01

    Acceleration of metabolism is defined as a long-term increase of respiration, that is faster than the typical trajectory during the life cycle of an individual, from embryo to adult. The Dynamic Energy Budget (DEB) model is used to quantify the typical trajectory. All DEB parameters were estimated for over 300 animal species from most large phyla and all chordate classes. The goodness of fit is generally excellent, including embryo development (embryo weight, respiration, amount of yolk). Although many species match predictions for metabolic rates, particular taxa, including all those with larval development, but also ones with less clear larval stages, deviated and have a lower metabolic rate as embryo, compared to late juvenile and adult stages: they accelerate their metabolism during the life cycle. Five different types of acceleration are identified, examples are given, and methods are presented to recognise these different types. Associated life history traits are discussed in an evolutionary and ecological context. Arguments are presented for why accelerating species have an extra slow start of metabolism and why parental care evolved in endotherms.

  5. Gene duplication and an accelerated evolutionary rate in 11S globulin genes are associated with higher protein synthesis in dicots as compared to monocots

    Li Chun; Li Meng; Dunwell Jim M; Zhang Yuan-Ming

    2012-01-01

    Abstract Background Seed storage proteins are a major source of dietary protein, and the content of such proteins determines both the quantity and quality of crop yield. Significantly, examination of the protein content in the seeds of crop plants shows a distinct difference between monocots and dicots. Thus, it is expected that there are different evolutionary patterns in the genes underlying protein synthesis in the seeds of these two groups of plants. Results Gene duplication, evolutionary...

  6. Inferring the determinants of protein evolutionary rates in mammals.

    Zou, Yang; Shao, Xiaojian; Dong, Dong

    2016-06-15

    Understanding the determinants of protein evolutionary rates is one of the most fundamental evolutionary questions. Previous studies have revealed that many biological variables are tightly associated with protein evolutionary rates in mammals. However, the dominant role of these biological variables and their combinatorial effects to evolutionary rates of mammalian proteins are still less understood. In this work, we derived a quantitative model to correlate protein evolutionary rates with the levels of these variables. The result showed that only a small number of variables are necessary to accurately predict protein evolutionary rates, among which miRNA regulation plays the most important role. Our result suggested that biological variables are extensively interrelated and suffer from hidden redundancies in determining protein evolutionary rates. Various variables should be considered in a natural ensemble to comprehensively assess the determinants of protein evolutionary rate. PMID:26899866

  7. The evolutionary rate dynamically tracks changes in HIV-1 epidemics

    Maljkovic-berry, Irina [Los Alamos National Laboratory; Athreya, Gayathri [Los Alamos National Laboratory; Daniels, Marcus [Los Alamos National Laboratory; Bruno, William [Los Alamos National Laboratory; Korber, Bette [Los Alamos National Laboratory; Kuiken, Carla [Los Alamos National Laboratory; Ribeiro, Ruy M [Los Alamos National Laboratory

    2009-01-01

    Large-sequence datasets provide an opportunity to investigate the dynamics of pathogen epidemics. Thus, a fast method to estimate the evolutionary rate from large and numerous phylogenetic trees becomes necessary. Based on minimizing tip height variances, we optimize the root in a given phylogenetic tree to estimate the most homogenous evolutionary rate between samples from at least two different time points. Simulations showed that the method had no bias in the estimation of evolutionary rates and that it was robust to tree rooting and topological errors. We show that the evolutionary rates of HIV-1 subtype B and C epidemics have changed over time, with the rate of evolution inversely correlated to the rate of virus spread. For subtype B, the evolutionary rate slowed down and tracked the start of the HAART era in 1996. Subtype C in Ethiopia showed an increase in the evolutionary rate when the prevalence increase markedly slowed down in 1995. Thus, we show that the evolutionary rate of HIV-1 on the population level dynamically tracks epidemic events.

  8. Proterozoic and early Cambrian protists: evidence for accelerating evolutionary tempo

    Knoll, A. H.

    1994-01-01

    In rocks of late Paleoproterozoic and Mesoproterozoic age (ca. 1700-1000 million years ago), probable eukaryotic microfossils are widespread and well preserved, but assemblage and global diversities are low and turnover is slow. Near the Mesoproterozoic-Neoproterozoic boundary (1000 million years ago), red, green, and chromophytic algae diversified; molecular phylogenies suggest that this was part of a broader radiation of "higher" eukaryotic phyla. Observed diversity levels for protistan microfossils increased significantly at this time, as did turnover rates. Coincident with the Cambrian radiation of marine invertebrates, protistan microfossils again doubled in diversity and rates of turnover increased by an order of magnitude. Evidently, the Cambrian diversification of animals strongly influenced evolutionary rates, within clades already present in marine communities, implying an important role for ecology in fueling a Cambrian explosion that extends across kingdoms.

  9. Evolutionary rate patterns of the Gibberellin pathway genes

    Zhang Fu-min

    2009-08-01

    Full Text Available Abstract Background Analysis of molecular evolutionary patterns of different genes within metabolic pathways allows us to determine whether these genes are subject to equivalent evolutionary forces and how natural selection shapes the evolution of proteins in an interacting system. Although previous studies found that upstream genes in the pathway evolved more slowly than downstream genes, the correlation between evolutionary rate and position of the genes in metabolic pathways as well as its implications in molecular evolution are still less understood. Results We sequenced and characterized 7 core structural genes of the gibberellin biosynthetic pathway from 8 representative species of the rice tribe (Oryzeae to address alternative hypotheses regarding evolutionary rates and patterns of metabolic pathway genes. We have detected significant rate heterogeneity among 7 GA pathway genes for both synonymous and nonsynonymous sites. Such rate variation is mostly likely attributed to differences of selection intensity rather than differential mutation pressures on the genes. Unlike previous argument that downstream genes in metabolic pathways would evolve more slowly than upstream genes, the downstream genes in the GA pathway did not exhibited the elevated substitution rate and instead, the genes that encode either the enzyme at the branch point (GA20ox or enzymes catalyzing multiple steps (KO, KAO and GA3ox in the pathway had the lowest evolutionary rates due to strong purifying selection. Our branch and codon models failed to detect signature of positive selection for any lineage and codon of the GA pathway genes. Conclusion This study suggests that significant heterogeneity of evolutionary rate of the GA pathway genes is mainly ascribed to differential constraint relaxation rather than the positive selection and supports the pathway flux theory that predicts that natural selection primarily targets enzymes that have the greatest control on fluxes.

  10. Evolutionary comparison between viral lysis rate and latent period.

    Bonachela, Juan A; Levin, Simon A

    2014-03-21

    Marine viruses shape the structure of the microbial community. They are, thus, a key determinant of the most important biogeochemical cycles in the planet. Therefore, a correct description of the ecological and evolutionary behavior of these viruses is essential to make reliable predictions about their role in marine ecosystems. The infection cycle, for example, is indistinctly modeled in two very different ways. In one representation, the process is described including explicitly a fixed delay between infection and offspring release. In the other, the offspring are released at exponentially distributed times according to a fixed release rate. By considering obvious quantitative differences pointed out in the past, the latter description is widely used as a simplification of the former. However, it is still unclear how the dichotomy "delay versus rate description" affects long-term predictions of host-virus interaction models. Here, we study the ecological and evolutionary implications of using one or the other approaches, applied to marine microbes. To this end, we use mathematical and eco-evolutionary computational analysis. We show that the rate model exhibits improved competitive abilities from both ecological and evolutionary perspectives in steady environments. However, rate-based descriptions can fail to describe properly long-term microbe-virus interactions. Moreover, additional information about trade-offs between life-history traits is needed in order to choose the most reliable representation for oceanic bacteriophage dynamics. This result affects deeply most of the marine ecosystem models that include viruses, especially when used to answer evolutionary questions. PMID:24361326

  11. Time Dependency of Molecular Evolutionary Rates? Yes and No

    Subramanian, Sankar; Lambert, David M.

    2011-01-01

    Some previous studies have suggested that rates of evolution inferred using molecular sequences vary substantially depending on the time frame over which they are measured, whereas a number of other studies have argued against this proposition. We examined this issue by separating positions of primate mitochondrial genomes that are under different levels of selection constraints. Our results revealed an order of magnitude variation in the evolutionary rates at constrained sites (including non...

  12. Evolutionary rate variation and RNA secondary structure prediction

    Knudsen, B; Andersen, E S; Damgaard, Christian Kroun;

    2004-01-01

    regions. In addition we obtained an alignment of the 5' HIV-1 region that is more consistent with the structure than that currently in the database. We added randomized noise to the original values of the rates to investigate the stability of predictions to rate matrix deviations. We find that changes...... by applying rates derived from tRNA and rRNA to the prediction of the much more rapidly evolving 5'-region of HIV-1. We find that the HIV-1 prediction is in agreement with experimental data, even though the relative evolutionary rate between A and G is significantly increased, both in stem and loop...... of approach. Determining these rates can be hard to do reliably without a large and accurate initial alignment, which ideally also has structural annotation. Hence, one must often apply rates extracted from other RNA families with trusted alignments and structures. Here, we investigate this problem...

  13. MEASURING THE EVOLUTIONARY RATE OF COOLING OF ZZ Ceti

    Mukadam, Anjum S.; Fraser, Oliver; Riecken, T. S.; Kronberg, M. E. [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Bischoff-Kim, Agnes [Georgia College and State University, Milledgeville, GA 31061 (United States); Corsico, A. H. [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata (Argentina); Montgomery, M. H.; Winget, D. E.; Hermes, J. J.; Winget, K. I.; Falcon, Ross E.; Reaves, D. [Department of Astronomy, University of Texas at Austin, Austin, TX 78759 (United States); Kepler, S. O.; Romero, A. D. [Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970, RS (Brazil); Chandler, D. W. [Meyer Observatory, Central Texas Astronomical Society, 3409 Whispering Oaks, Temple, TX 76504 (United States); Kuehne, J. W. [McDonald Observatory, Fort Davis, TX 79734 (United States); Sullivan, D. J. [Victoria University of Wellington, P.O. Box 600, Wellington (New Zealand); Von Hippel, T. [Embry-Riddle Aeronautical University, 600 South Clyde Morris Boulevard, Daytona Beach, FL 32114 (United States); Mullally, F. [SETI Institute, NASA Ames Research Center, MS 244-30, Moffet Field, CA 94035 (United States); Shipman, H. [Delaware Asteroseismic Research Center, Mt. Cuba Observatory, Greenville, DE 19807 (United States); and others

    2013-07-01

    We have finally measured the evolutionary rate of cooling of the pulsating hydrogen atmosphere (DA) white dwarf ZZ Ceti (Ross 548), as reflected by the drift rate of the 213.13260694 s period. Using 41 yr of time-series photometry from 1970 November to 2012 January, we determine the rate of change of this period with time to be dP/dt = (5.2 {+-} 1.4) Multiplication-Sign 10{sup -15} s s{sup -1} employing the O - C method and (5.45 {+-} 0.79) Multiplication-Sign 10{sup -15} s s{sup -1} using a direct nonlinear least squares fit to the entire lightcurve. We adopt the dP/dt obtained from the nonlinear least squares program as our final determination, but augment the corresponding uncertainty to a more realistic value, ultimately arriving at the measurement of dP/dt = (5.5 {+-} 1.0) Multiplication-Sign 10{sup -15} s s{sup -1}. After correcting for proper motion, the evolutionary rate of cooling of ZZ Ceti is computed to be (3.3 {+-} 1.1) Multiplication-Sign 10{sup -15} s s{sup -1}. This value is consistent within uncertainties with the measurement of (4.19 {+-} 0.73) Multiplication-Sign 10{sup -15} s s{sup -1} for another similar pulsating DA white dwarf, G 117-B15A. Measuring the cooling rate of ZZ Ceti helps us refine our stellar structure and evolutionary models, as cooling depends mainly on the core composition and stellar mass. Calibrating white dwarf cooling curves with this measurement will reduce the theoretical uncertainties involved in white dwarf cosmochronometry. Should the 213.13 s period be trapped in the hydrogen envelope, then our determination of its drift rate compared to the expected evolutionary rate suggests an additional source of stellar cooling. Attributing the excess cooling to the emission of axions imposes a constraint on the mass of the hypothetical axion particle.

  14. Time dependency of molecular evolutionary rates? Yes and no.

    Subramanian, Sankar; Lambert, David M

    2011-01-01

    Some previous studies have suggested that rates of evolution inferred using molecular sequences vary substantially depending on the time frame over which they are measured, whereas a number of other studies have argued against this proposition. We examined this issue by separating positions of primate mitochondrial genomes that are under different levels of selection constraints. Our results revealed an order of magnitude variation in the evolutionary rates at constrained sites (including nonsynonymous sites, D-loop, and RNA) and virtually an identical rate of evolution at synonymous sites, independent of the timescales over which they were estimated. Although the evolutionary rate at nonsynonymous sites obtained using the European (H1 haplogroup) mitogenomes is 9-15 times higher than that estimated using the human-chimpanzee pair, in contrast, the rates at synonymous sites are similar between these comparisons. We also show that the ratio of divergence at nonsynonymous to synonymous sites estimated using intra- and interspecific comparisons vary up to nine times, which corroborates our results independent of calibration times. PMID:22016336

  15. Mutation and evolutionary rates in adelie penguins from the antarctic.

    Craig D Millar

    Full Text Available Precise estimations of molecular rates are fundamental to our understanding of the processes of evolution. In principle, mutation and evolutionary rates for neutral regions of the same species are expected to be equal. However, a number of recent studies have shown that mutation rates estimated from pedigree material are much faster than evolutionary rates measured over longer time periods. To resolve this apparent contradiction, we have examined the hypervariable region (HVR I of the mitochondrial genome using families of Adélie penguins (Pygoscelis adeliae from the Antarctic. We sequenced 344 bps of the HVR I from penguins comprising 508 families with 915 chicks, together with both their parents. All of the 62 germline heteroplasmies that we detected in mothers were also detected in their offspring, consistent with maternal inheritance. These data give an estimated mutation rate (micro of 0.55 mutations/site/Myrs (HPD 95% confidence interval of 0.29-0.88 mutations/site/Myrs after accounting for the persistence of these heteroplasmies and the sensitivity of current detection methods. In comparison, the rate of evolution (k of the same HVR I region, determined using DNA sequences from 162 known age sub-fossil bones spanning a 37,000-year period, was 0.86 substitutions/site/Myrs (HPD 95% confidence interval of 0.53 and 1.17. Importantly, the latter rate is not statistically different from our estimate of the mutation rate. These results are in contrast to the view that molecular rates are time dependent.

  16. Ascomycota has a faster evolutionary rate and higher species diversity than Basidiomycota

    Lumbsch; H.; THORSTEN

    2010-01-01

    Differences in rates of nucleotide or amino acid substitutions among major groups of organisms are repeatedly found and well documented. A growing body of evidence suggests a link between the rate of neutral molecular change within populations and the evolution of species diversity. More than 98% of terrestrial fungi belong to the phyla Ascomycota or Basidiomycota. The former is considerably richer in number of species than the latter. We obtained DNA sequences of 21 protein-coding genes from the lichenized fungus Rhizoplaca chrysoleuca and used them together with sequences from GenBank for subsequent analyses. Three datasets were used to test rate discrepancies between Ascomycota and Basidiomycota and that within Ascomycota: (i) 13 taxa including 105 protein-coding genes, (ii) nine taxa including 21 protein-coding genes, and (iii) nuclear LSU rDNA of 299 fungal species. Based on analyses of the 105 protein-coding genes and nuclear LSU rDNA datasets, we found that the evolutionary rate was higher in Ascomycota than in Basidiomycota. The differences in substitution rates between Ascomycota and Basidiomycota were significant. Within Ascomycota, the species-rich Sordariomycetes has the fastest evolutionary rate, while Leotiomycetes has the slowest. Our results indicate that the main contribution to the higher substitution rates in Ascomycota does not come from mutualism, ecological conditions, sterility, metabolic rate or shorter generation time, but is possibly caused by the founder effect. This is another example of the correlation between species number and evolutionary rates, which is consistent with the hypothesis that the founder effect is responsible for accelerated substitution rates in diverse clades.

  17. Characterization of evolutionary rates and constraints in three mammalian genomes

    Cooper, Gregory M.; Brudno, Michael; Stone, Eric A.; Dubchak, Inna; Batzoglou, Serafim; Sidow, Arend

    2004-02-15

    We present an analysis of rates and patterns of microevolutionary phenomena that have shaped the human, mouse, and rat genomes since their last common ancestor. We find evidence for a shift in the mutational spectrum between the mouse and rat lineages, with the net effect being a relative increase in GC content in the rat genome. Our estimate for the neutral point substitution rate separating the two rodents is 0.196 substitutions per site, and 0.65 substitutions per site for the tree relating all three mammals. Small insertions and deletions of 1-10 bp in length (''microindels'') occur at approximately 5 percent of the point substitution rate. Inferred regional correlations in evolutionary rates between lineages and between types of sites support the idea that rates of evolution are influenced by local genomic or cell biological context. No substantial correlations between rates of point substitutions and rates of microindels are found, however, implying that the influences that affect these processes are distinct. Finally, we have identified those regions in the human genome that are evolving slowly, which are likely to include functional elements important to human biology. At least 5 percent of the human genome is under substantial constraint, most of which is noncoding.

  18. A Discrete Evolutionary Model for Chess Players' Ratings

    Fenner, Trevor; Loizou, George

    2011-01-01

    The Elo system for rating chess players, also used in other games and sports, was adopted by the World Chess Federation over four decades ago. Although not without controversy, it is accepted as generally reliable and provides a method for assessing players' strengths and ranking them in official tournaments. It is generally accepted that the distribution of players' rating data is approximately normal but, to date, no stochastic model of how the distribution might have arisen has been proposed. We propose such an evolutionary stochastic model, which models the arrival of players into the rating pool, the games they play against each other, and how the results of these games affect their ratings. Using a continuous approximation to the discrete model, we derive the distribution for players' ratings at time $t$ as a normal distribution, where the variance increases in time as a logarithmic function of $t$. We validate the model using published rating data from 2007 to 2010, showing that the parameters obtained...

  19. Measuring the evolutionary rate of protein–protein interaction

    Qian, Wenfeng; He, Xionglei; Chan, Edwin; Xu, Huailiang; Zhang, Jianzhi

    2011-01-01

    Despite our extensive knowledge about the rate of protein sequence evolution for thousands of genes in hundreds of species, the corresponding rate of protein function evolution is virtually unknown, especially at the genomic scale. This lack of knowledge is primarily because of the huge diversity in protein function and the consequent difficulty in gauging and comparing rates of protein function evolution. Nevertheless, most proteins function through interacting with other proteins, and prote...

  20. Does Sex Speed Up Evolutionary Rate and Increase Biodiversity?

    Melian Penate, Carlos Javier; Alonso, David; Allesina, Stefano; Condit, Richard S.; Etienne, Rampal S.

    2012-01-01

    Most empirical and theoretical studies have shown that sex increases the rate of evolution, although evidence of sex constraining genomic and epigenetic variation and slowing down evolution also exists. Faster rates with sex have been attributed to new gene combinations, removal of deleterious mutations, and adaptation to heterogeneous environments. Slower rates with sex have been attributed to removal of major genetic rearrangements, the cost of finding a mate, vulnerability to predation, an...

  1. Reduced evolutionary rate in reemerged Ebola virus transmission chains.

    Blackley, David J; Wiley, Michael R; Ladner, Jason T; Fallah, Mosoka; Lo, Terrence; Gilbert, Merle L; Gregory, Christopher; D'ambrozio, Jonathan; Coulter, Stewart; Mate, Suzanne; Balogun, Zephaniah; Kugelman, Jeffrey; Nwachukwu, William; Prieto, Karla; Yeiah, Adolphus; Amegashie, Fred; Kearney, Brian; Wisniewski, Meagan; Saindon, John; Schroth, Gary; Fakoli, Lawrence; Diclaro, Joseph W; Kuhn, Jens H; Hensley, Lisa E; Jahrling, Peter B; Ströher, Ute; Nichol, Stuart T; Massaquoi, Moses; Kateh, Francis; Clement, Peter; Gasasira, Alex; Bolay, Fatorma; Monroe, Stephan S; Rambaut, Andrew; Sanchez-Lockhart, Mariano; Scott Laney, A; Nyenswah, Tolbert; Christie, Athalia; Palacios, Gustavo

    2016-04-01

    On 29 June 2015, Liberia's respite from Ebola virus disease (EVD) was interrupted for the second time by a renewed outbreak ("flare-up") of seven confirmed cases. We demonstrate that, similar to the March 2015 flare-up associated with sexual transmission, this new flare-up was a reemergence of a Liberian transmission chain originating from a persistently infected source rather than a reintroduction from a reservoir or a neighboring country with active transmission. Although distinct, Ebola virus (EBOV) genomes from both flare-ups exhibit significantly low genetic divergence, indicating a reduced rate of EBOV evolution during persistent infection. Using this rate of change as a signature, we identified two additional EVD clusters that possibly arose from persistently infected sources. These findings highlight the risk of EVD flare-ups even after an outbreak is declared over. PMID:27386513

  2. Assessing fluctuating evolutionary pressure in yeast and mammal evolutionary rate covariation using bioinformatics of meiotic protein genetic sequences

    Dehipawala, Sunil; Nguyen, A.; Tremberger, G.; Cheung, E.; Holden, T.; Lieberman, D.; Cheung, T.

    2013-09-01

    The evolutionary rate co-variation in meiotic proteins has been reported for yeast and mammal using phylogenic branch lengths which assess retention, duplication and mutation. The bioinformatics of the corresponding DNA sequences could be classified as a diagram of fractal dimension and Shannon entropy. Results from biomedical gene research provide examples on the diagram methodology. The identification of adaptive selection using entropy marker and functional-structural diversity using fractal dimension would support a regression analysis where the coefficient of determination would serve as evolutionary pathway marker for DNA sequences and be an important component in the astrobiology community. Comparisons between biomedical genes such as EEF2 (elongation factor 2 human, mouse, etc), WDR85 in epigenetics, HAR1 in human specificity, clinical trial targeted cancer gene CD47, SIRT6 in spermatogenesis, and HLA-C in mosquito bite immunology demonstrate the diagram classification methodology. Comparisons to the SEPT4-XIAP pair in stem cell apoptosis, testesexpressed taste genes TAS1R3-GNAT3 pair, and amyloid beta APLP1-APLP2 pair with the yeast-mammal DNA sequences for meiotic proteins RAD50-MRE11 pair and NCAPD2-ICK pair have accounted for the observed fluctuating evolutionary pressure systematically. Regression with high R-sq values or a triangular-like cluster pattern for concordant pairs in co-variation among the studied species could serve as evidences for the possible location of common ancestors in the entropy-fractal dimension diagram, consistent with an example of the human-chimp common ancestor study using the FOXP2 regulated genes reported in human fetal brain study. The Deinococcus radiodurans R1 Rad-A could be viewed as an outlier in the RAD50 diagram and also in the free energy versus fractal dimension regression Cook's distance, consistent with a non-Earth source for this radiation resistant bacterium. Convergent and divergent fluctuating evolutionary

  3. Exploring the evolutionary rate differences between human disease and non-disease genes.

    Chakraborty, Sandip; Panda, Arup; Ghosh, Tapash Chandra

    2016-07-01

    Comparisons of evolutionary features between human disease and non-disease genes have a wide implication to understand the genetic basis of human disease genes. However, it has not yet been resolved whether disease genes evolve at slower or faster rate than the non-disease genes. To resolve this controversy, here we integrated human disease genes from several databases and compared their protein evolutionary rates with non-disease genes in both housekeeping and tissue-specific group. We noticed that in tissue specific group, disease genes evolve significantly at a slower rate than non-disease genes. However, we found no significant difference in evolutionary rates between disease and non-disease genes in housekeeping group. Tissue specific disease genes have a higher protein complex number, elevated gene expression level and are also associated with conserve biological processes. Finally, our regression analysis suggested that protein complex number followed by protein multifunctionality independently modulates the evolutionary rate of human disease genes. PMID:26562439

  4. The structure of heart rate asymmetry: deceleration and acceleration runs

    A family of new heart rate asymmetry measures is introduced, namely deceleration and acceleration runs, as well as entropic measures summarizing their distribution. We introduce the theoretical run distribution for shuffled data and use it as a reference for interpreting the results. The measures defined in the paper are applied to actual 24 h Holter ECG recordings from 87 healthy people, and it is demonstrated that the patterns of accelerations are different from those of decelerations. Acceleration runs are longer and more numerous: all runs of accelerations, with the exception of lengths 3 and 4, are more numerous than those of decelerations. These findings are reflected in the difference between the entropic measures for acceleration and deceleration runs: for 74 subjects the acceleration-related entropic parameter is greater than that of decelerations (p < 0.001). For shuffled data there is no difference in the above parameters, and there are more short runs and fewer long runs than in physiological data. The influence of the measuring equipment resolution is also discussed

  5. Accelerating degradation rate of pure iron by zinc ion implantation.

    Huang, Tao; Zheng, Yufeng; Han, Yong

    2016-12-01

    Pure iron has been considered as a promising candidate for biodegradable implant applications. However, a faster degradation rate of pure iron is needed to meet the clinical requirement. In this work, metal vapor vacuum arc technology was adopted to implant zinc ions into the surface of pure iron. Results showed that the implantation depth of zinc ions was about 60 nm. The degradation rate of pure iron was found to be accelerated after zinc ion implantation. The cytotoxicity tests revealed that the implanted zinc ions brought a slight increase on cytotoxicity of the tested cells. In terms of hemocompatibility, the hemolysis of zinc ion implanted pure iron was lower than 2%. However, zinc ions might induce more adhered and activated platelets on the surface of pure iron. Overall, zinc ion implantation can be a feasible way to accelerate the degradation rate of pure iron for biodegradable applications. PMID:27482462

  6. A count rate based contamination control standard for electron accelerators

    May, R.T.; Schwahn, S.O.

    1996-12-31

    Accelerators of sufficient energy and particle fluence can produce radioactivity as an unwanted byproduct. The radioactivity is typically imbedded in structural materials but may also be removable from surfaces. Many of these radionuclides decay by positron emission or electron capture; they often have long half lives and produce photons of low energy and yield making detection by standard devices difficult. The contamination control limit used throughout the US nuclear industry and the Department of Energy is 1,000 disintegrations per minute. This limit is based on the detection threshold of pancake type Geiger-Mueller probes for radionuclides of relatively high radiotoxicity, such as cobalt-60. Several radionuclides of concern at a high energy electron accelerator are compared in terms of radiotoxicity with radionuclides commonly found in the nuclear industry. Based on this comparison, a count-rate based contamination control limit and associated measurement strategy is proposed which provides adequate detection of contamination at accelerators without an increase in risk.

  7. LS³: A Method for Improving Phylogenomic Inferences When Evolutionary Rates Are Heterogeneous among Taxa

    Rivera-Rivera, Carlos J.; Montoya-Burgos, Juan I.

    2016-01-01

    Phylogenetic inference artifacts can occur when sequence evolution deviates from assumptions made by the models used to analyze them. The combination of strong model assumption violations and highly heterogeneous lineage evolutionary rates can become problematic in phylogenetic inference, and lead to the well-described long-branch attraction (LBA) artifact. Here, we define an objective criterion for assessing lineage evolutionary rate heterogeneity among predefined lineages: the result of a likelihood ratio test between a model in which the lineages evolve at the same rate (homogeneous model) and a model in which different lineage rates are allowed (heterogeneous model). We implement this criterion in the algorithm Locus Specific Sequence Subsampling (LS³), aimed at reducing the effects of LBA in multi-gene datasets. For each gene, LS³ sequentially removes the fastest-evolving taxon of the ingroup and tests for lineage rate homogeneity until all lineages have uniform evolutionary rates. The sequences excluded from the homogeneously evolving taxon subset are flagged as potentially problematic. The software implementation provides the user with the possibility to remove the flagged sequences for generating a new concatenated alignment. We tested LS³ with simulations and two real datasets containing LBA artifacts: a nucleotide dataset regarding the position of Glires within mammals and an amino-acid dataset concerning the position of nematodes within bilaterians. The initially incorrect phylogenies were corrected in all cases upon removing data flagged by LS³. PMID:26912812

  8. Cumulative Causation and Evolutionary Micro-Founded Technical Change. On the Determinants of Growth rate Differences

    Patrick Llerena; André Lorentz

    2004-01-01

    We develop in this paper an alternative approach to the New Growth Theory to analyse growth rate differences among integrated economies. The model presented here considers economic growth as a disequilibrium process. It introduces in a cumulative causation framework, micro-founded process of technical change taking into account elements rooted in evolutionary and Neo-Austrian literature. We then attempt to open the ??Kaldor-Verdoorn law black-box?? using a microlevel modelling of industrial d...

  9. The non-random clustering of non-synonymous substitutions and its relationship to evolutionary rate

    Stone Eric A

    2011-08-01

    Full Text Available Abstract Background Protein sequences are subject to a mosaic of constraint. Changes to functional domains and buried residues, for example, are more apt to disrupt protein structure and function than are changes to residues participating in loops or exposed to solvent. Regions of constraint on the tertiary structure of a protein often result in loose segmentation of its primary structure into stretches of slowly- and rapidly-evolving amino acids. This clustering can be exploited, and existing methods have done so by relying on local sequence conservation as a signature of selection to help identify functionally important regions within proteins. We invert this paradigm by leveraging the regional nature of protein structure and function to both illuminate and make use of genome-wide patterns of local sequence conservation. Results Our hypothesis is that the regional nature of structural and functional constraints will assert a positive autocorrelation on the evolutionary rates of neighboring sites, which, in a pairwise comparison of orthologous proteins, will manifest itself as the clustering of non-synonymous changes across the amino acid sequence. We introduce a dispersion ratio statistic to test this and related hypotheses. Using genome-wide interspecific comparisons of orthologous protein pairs, we reveal a strong log-linear relationship between the degree of clustering and the intensity of constraint. We further demonstrate how this relationship varies with the evolutionary distance between the species being compared. We provide some evidence that proteins with a history of positive selection deviate from genome-wide trends. Conclusions We find a significant association between the evolutionary rate of a protein and the degree to which non-synonymous changes cluster along its primary sequence. We show that clustering is a non-redundant predictor of evolutionary rate, and we speculate that conflicting signals of clustering and constraint may

  10. Radiation shielding and dose rate distribution for the building of the high dose rate accelerator

    A high dose rate electron accelerator was established at Osaka Laboratory for Radiation Chemistry, Takasaki Establishment, JAERI in the fiscal year of 1975. This report shows the fundamental concept for the radiation shielding of the accelerator building and the results of their calculations which were evaluated through the model experiments. After the construction of the building, the leak radiation was measured in order to evaluate the calculating method of radiation shielding. Dose rate distribution of X-rays was also measured in the whole area of the irradiation room as a data base. (author)

  11. Human microRNAs originated from two periods at accelerated rates in mammalian evolution.

    Iwama, Hisakazu; Kato, Kiyohito; Imachi, Hitomi; Murao, Koji; Masaki, Tsutomu

    2013-03-01

    MicroRNAs (miRNAs) are short, noncoding RNAs that modulate genes posttranscriptionally. Frequent gains and losses of miRNA genes have been reported to occur during evolution. However, little is known systematically about the periods of evolutionary origin of the present miRNA gene repertoire of an extant mammalian species. Thus, in this study, we estimated the evolutionary periods during which each of 1,433 present human miRNA genes originated within 15 periods, from human to platypus-human common ancestral branch and a class "conserved beyond theria," primarily using multiple genome alignments of 38 species, plus the pairwise genome alignments of five species. The results showed two peak periods in which the human miRNA genes originated at significantly accelerated rates. The most accelerated rate appeared in the period of the initial phase of hominoid lineage, and the second appeared shortly before Laurasiatherian divergence. Approximately 53% of the present human miRNA genes have originated within the simian lineage to human. In particular, approximately 28% originated within the hominoid lineage. The early phase of placental mammal radiation comprises approximately 28%, while no more than 15% of human miRNAs have been conserved beyond placental mammals. We also clearly showed a general trend, in which the miRNA expression level decreases as the miRNA becomes younger. Intriguingly, amid this decreasing trend of expression, we found one significant rise in the expression level that corresponded to the initial phase of the hominoid lineage, suggesting that increased functional acquisitions of miRNAs originated at this particular period. PMID:23171859

  12. Mechanistic model of evolutionary rate variation en route to a nonphotosynthetic lifestyle in plants.

    Wicke, Susann; Müller, Kai F; dePamphilis, Claude W; Quandt, Dietmar; Bellot, Sidonie; Schneeweiss, Gerald M

    2016-08-01

    Because novel environmental conditions alter the selection pressure on genes or entire subgenomes, adaptive and nonadaptive changes will leave a measurable signature in the genomes, shaping their molecular evolution. We present herein a model of the trajectory of plastid genome evolution under progressively relaxed functional constraints during the transition from autotrophy to a nonphotosynthetic parasitic lifestyle. We show that relaxed purifying selection in all plastid genes is linked to obligate parasitism, characterized by the parasite's dependence on a host to fulfill its life cycle, rather than the loss of photosynthesis. Evolutionary rates and selection pressure coevolve with macrostructural and microstructural changes, the extent of functional reduction, and the establishment of the obligate parasitic lifestyle. Inferred bursts of gene losses coincide with periods of relaxed selection, which are followed by phases of intensified selection and rate deceleration in the retained functional complexes. Our findings suggest that the transition to obligate parasitism relaxes functional constraints on plastid genes in a stepwise manner. During the functional reduction process, the elevation of evolutionary rates reaches several new rate equilibria, possibly relating to the modified protein turnover rates in heterotrophic plastids. PMID:27450087

  13. Flagellated algae protein evolution suggests the prevalence of lineage-specific rules governing evolutionary rates of eukaryotic proteins.

    Chang, Ting-Yan; Liao, Ben-Yang

    2013-01-01

    Understanding the general rules governing the rate of protein evolution is fundamental to evolutionary biology. However, attempts to address this issue in yeasts and mammals have revealed considerable differences in the relative importance of determinants for protein evolutionary rates. This phenomenon was previously explained by the fact that yeasts and mammals are different in many cellular and genomic properties. Flagellated algae species have several cellular and genomic characteristics that are intermediate between yeasts and mammals. Using partial correlation analyses on the evolution of 6,921 orthologous proteins from Chlamydomonas reinhardtii and Volvox carteri, we examined factors influencing evolutionary rates of proteins in flagellated algae. Previous studies have shown that mRNA abundance and gene compactness are strong determinants for protein evolutionary rates in yeasts and mammals, respectively. We show that both factors also influence algae protein evolution with mRNA abundance having a larger impact than gene compactness on the rates of algae protein evolution. More importantly, among all the factors examined, coding sequence (CDS) length has the strongest (positive) correlation with protein evolutionary rates. This correlation between CDS length and the rates of protein evolution is not due to alignment-related issues or domain density. These results suggest no simple and universal rules governing protein evolutionary rates across different eukaryotic lineages. Instead, gene properties influence the rate of protein evolution in a lineage-specific manner. PMID:23563973

  14. Flagellated Algae Protein Evolution Suggests the Prevalence of Lineage-Specific Rules Governing Evolutionary Rates of Eukaryotic Proteins

    Chang, Ting-Yan; Liao, Ben-Yang

    2013-01-01

    Understanding the general rules governing the rate of protein evolution is fundamental to evolutionary biology. However, attempts to address this issue in yeasts and mammals have revealed considerable differences in the relative importance of determinants for protein evolutionary rates. This phenomenon was previously explained by the fact that yeasts and mammals are different in many cellular and genomic properties. Flagellated algae species have several cellular and genomic characteristics t...

  15. GPU accelerated processing of astronomical high frame-rate videosequences

    Vítek, Stanislav; Švihlík, Jan; Krasula, Lukáš; Fliegel, Karel; Páta, Petr

    2015-09-01

    Astronomical instruments located around the world are producing an incredibly large amount of possibly interesting scientific data. Astronomical research is expanding into large and highly sensitive telescopes. Total volume of data rates per night of operations also increases with the quality and resolution of state-of-the-art CCD/CMOS detectors. Since many of the ground-based astronomical experiments are placed in remote locations with limited access to the Internet, it is necessary to solve the problem of the data storage. It mostly means that current data acquistion, processing and analyses algorithm require review. Decision about importance of the data has to be taken in very short time. This work deals with GPU accelerated processing of high frame-rate astronomical video-sequences, mostly originating from experiment MAIA (Meteor Automatic Imager and Analyser), an instrument primarily focused to observing of faint meteoric events with a high time resolution. The instrument with price bellow 2000 euro consists of image intensifier and gigabite ethernet camera running at 61 fps. With resolution better than VGA the system produces up to 2TB of scientifically valuable video data per night. Main goal of the paper is not to optimize any GPU algorithm, but to propose and evaluate parallel GPU algorithms able to process huge amount of video-sequences in order to delete all uninteresting data.

  16. Heterogeneous evolutionary rates of Pi2/9 homologs in rice

    Wu Kejing

    2012-08-01

    Full Text Available Abstract Background The Pi2/9 locus contains multiple nucleotide binding site–leucine-rich repeat (NBS-LRR genes in the rice genome. Although three functional R-genes have been cloned from this locus, little is known about the origin and evolutionary history of these genes. Herein, an extensive genome-wide survey of Pi2/9 homologs in rice, sorghum, Brachypodium and Arabidopsis, was conducted to explore this theme. Results In our study, 1, 1, 5 and 156 Pi2/9 homologs were detected in Arabidopsis, Brachypodium, sorghum and rice genomes, respectively. Two distinct evolutionary patterns of Pi2/9 homologs, Type I and Type II, were observed in rice lines. Type I Pi2/9 homologs showed evidence of rapid gene diversification, including substantial copy number variations, obscured orthologous relationships, high levels of nucleotide diversity or/and divergence, frequent sequence exchanges and strong positive selection, whereas Type II Pi2/9 homologs exhibited a fairly slow evolutionary rate. Interestingly, the three cloned R-genes from the Pi2/9 locus all belonged to the Type I genes. Conclusions Our data show that the Pi2/9 locus had an ancient origin predating the common ancestor of gramineous species. The existence of two types of Pi2/9 homologs suggest that diversifying evolution should be an important strategy of rice to cope with different types of pathogens. The relationship of cloned Pi2/9 genes and Type I genes also suggests that rapid gene diversification might facilitate rice to adapt quickly to the changing spectrum of the fungal pathogen M. grisea. Based on these criteria, other potential candidate genes that might confer novel resistance specificities to rice blast could be predicted.

  17. Hydrogen spark switches for rep-rated accelerators

    The Pulsed Power Technology Branch at NAVSWC is investigating high-power switch technologies for use in rep-rated, high-current accelerators. Switches are needed that can handle 10 kJ of energy, 500 kV, 100 kA, while operating with jitter less than 10 ns at repetition rates up to 10 kHz. In-house efforts have concentrated on spark-gap switches because of their high-voltage and high-current capabilities in single-shot devices and because of their simplicity and low cost. The authors have shown that hydrogen gas, with its high thermal diffusivity, allows an order-of magnitude improvement in the recovery time (and, therefore, repetition rate) of an unblown spark-gap switch. Recovery of the switch can be made even faster by triggering the switch well below its self-break voltage, allowing voltage to be reapplied while the gas is still hot. Tests have shown that recovery times (to the operating voltage) can be reduced an order-of-magnitude when the gap is undervolted by approximately 50%. The combination of high-pressure hydrogen gas and undervolted triggering provide a factor of 100 improvement over typical air spark gaps. Recent tests have demonstrated 100-μs recovery of an undervolted hydrogen spark gap without gas flow. High energy tests have been performed at 50 kV, 170 kA and 12 kJ with 100 μs recovery times. High voltage tests with a 5-pulse burst at 500 kV are presently underway. Recovery of the switch appears to be largely independent of voltage and energy transferred

  18. Minimizing the symbol-error-rate for amplify-and-forward relaying systems using evolutionary algorithms

    Ahmed, Qasim Zeeshan

    2015-02-01

    In this paper, a new detector is proposed for an amplify-and-forward (AF) relaying system. The detector is designed to minimize the symbol-error-rate (SER) of the system. The SER surface is non-linear and may have multiple minimas, therefore, designing an SER detector for cooperative communications becomes an optimization problem. Evolutionary based algorithms have the capability to find the global minima, therefore, evolutionary algorithms such as particle swarm optimization (PSO) and differential evolution (DE) are exploited to solve this optimization problem. The performance of proposed detectors is compared with the conventional detectors such as maximum likelihood (ML) and minimum mean square error (MMSE) detector. In the simulation results, it can be observed that the SER performance of the proposed detectors is less than 2 dB away from the ML detector. Significant improvement in SER performance is also observed when comparing with the MMSE detector. The computational complexity of the proposed detector is much less than the ML and MMSE algorithms. Moreover, in contrast to ML and MMSE detectors, the computational complexity of the proposed detectors increases linearly with respect to the number of relays.

  19. Evolutionary enhancement of the SLIM-MAUD method of estimating human error rates

    The methodology described in this paper assigns plant-specific dynamic human error rates (HERs) for individual plant examinations based on procedural difficulty, on configuration features, and on the time available to perform the action. This methodology is an evolutionary improvement of the success likelihood index methodology (SLIM-MAUD) for use in systemic scenarios. It is based on the assumption that the HER in a particular situation depends of the combined effects of a comprehensive set of performance-shaping factors (PSFs) that influence the operator's ability to perform the action successfully. The PSFs relate the details of the systemic scenario in which the action must be performed according to the operator's psychological and cognitive condition

  20. Eutherians experienced elevated evolutionary rates in the immediate aftermath of the Cretaceous–Palaeogene mass extinction

    Upchurch, Paul; Goswami, Anjali

    2016-01-01

    The effect of the Cretaceous–Palaeogene (K–Pg) mass extinction on the evolution of many groups, including placental mammals, has been hotly debated. The fossil record suggests a sudden adaptive radiation of placentals immediately after the event, but several recent quantitative analyses have reconstructed no significant increase in either clade origination rates or rates of character evolution in the Palaeocene. Here we use stochastic methods to date a recent phylogenetic analysis of Cretaceous and Palaeocene mammals and show that Placentalia likely originated in the Late Cretaceous, but that most intraordinal diversification occurred during the earliest Palaeocene. This analysis reconstructs fewer than 10 placental mammal lineages crossing the K–Pg boundary. Moreover, we show that rates of morphological evolution in the 5 Myr interval immediately after the K–Pg mass extinction are three times higher than background rates during the Cretaceous. These results suggest that the K–Pg mass extinction had a marked impact on placental mammal diversification, supporting the view that an evolutionary radiation occurred as placental lineages invaded new ecological niches during the Early Palaeocene. PMID:27358361

  1. Some Analytical Properties of the Model for Stochastic Evolutionary Games in Finite Populations with Non-uniform Interaction Rate

    QUAN Ji; WANG Xian-Jia

    2013-01-01

    Traditional evolutionary games assume uniform interaction rate,which means that the rate at which individuals meet and interact is independent of their strategies.But in some systems,especially biological systems,the players interact with each other discriminately.Taylor and Nowak (2006) were the first to establish the corresponding non-uniform interaction rate model by allowing the interaction rates to depend on strategies.Their model is based on replicator dynamics which assumes an infinite size population.But in reality,the number of individuals in the population is always finite,and there will be some random interference in the individuals' strategy selection process.Therefore,it is more practical to establish the corresponding stochastic evolutionary model in finite populations.In fact,the analysis of evolutionary games in a finite size population is more difficult.Just as Taylor and Nowak said in the outlook section of their paper,"The analysis of non-uniform interaction rates should be extended to stochastic game dynamics of finite populations." In this paper,we are exactly doing this work.We extend Taylor and Nowak's model from infinite to finite case,especially focusing on the influence of non-uniform connection characteristics on the evolutionary stable state of the system.We model the strategy evolutionary process of the population by a continuous ergodic Markov process.Based on the fimit distribution of the process,we can give the evolutionary stable state of the system.We make a complete classification of the symmetric 2 × 2 games.For each case game,the corresponding limit distribution of the Markov-based process is given when noise intensity is small enough.In contrast with most literatures in evolutionary games using the simulation method,all our results obtained are analytical.Especially,in the dominant-case game,coexistence of the two strategies may become evolutionary stable states in our model.This result can be used to explain the emergence of

  2. The Temporal Relationship between Infant Heart Rate Acceleration and Crying in an Aversive Situation.

    Vaughn, Brian; Sroufe, L. Alan

    1979-01-01

    Shows that the heart rate acceleration of 16 infants ranging in age from 8 to 16 months consistently began well before the onset of crying. This suggests that heart rate acceleration is not merely a by-product of crying but that it is associated with negative affect. (JMB)

  3. Existence, numerical convergence and evolutionary relaxation for a rate-independent phase-transformation model.

    Heinz, Sebastian; Mielke, Alexander

    2016-04-28

    We revisit the model for a two-well phase transformation in a linearly elastic body that was introduced and studied in Mielke et al. (2002 Arch. Ration. Mech. Anal. 162: , 137-177). This energetic rate-independent system is posed in terms of the elastic displacement and an internal variable that gives the phase portion of the second phase. We use a new approach based on mutual recovery sequences, which are adjusted to a suitable energy increment plus the associated dissipated energy and, thus, enable us to pass to the limit in the construction of energetic solutions. We give three distinct constructions of mutual recovery sequences which allow us (i) to generalize the existence result in Mielke et al. (2002), (ii) to establish the convergence of suitable numerical approximations via space-time discretization and (iii) to perform the evolutionary relaxation from the pure-state model to the relaxed-mixture model. All these results rely on weak converge and involve the H-measure as an essential tool. PMID:27002066

  4. Changes in acceleration rate of chloride ions depending on climatic conditions. Influence of rain

    Mild steel,copper and aluminum samples were exposed outdoors in two atmospheric test stations located in Havana, Cuba and Medellin, colombia. Two parallel group of samples were formed, one for each station. They were submitted to accelerated outdoor test by intermittent spraying of a salt solution (SCAB test) according to ISO 11474.98, receiving also the influence of the open atmosphere. The acceleration of corrosion rate of the three metals caused by the presence of chloride ions in both stations was determined. As expected, steel shows the higher corrosion rate and acceleration by chlorides, particularly at Cuban corrosion station. A remarkable difference in the acceleration rate of chloride ions for mild steel and copper between Cuban and Colombian acceleration rate of chloride ions of steel and copper. Steel corrosion products were analysed by Moessbauer Spectroscopy. Water absorption was also studied. The presence of magnetite, goethite and other Iron compounds was determined. (Author) 10 refs

  5. Near-Term Acceleration In The Rate of Temperature Change

    Smith, Steven J.; Edmonds, James A.; Hartin, Corinne A.; Mundra, Anupriya; Calvin, Katherine V.

    2015-03-09

    Anthropogenically-driven climate changes, which are expected to impact human and natural systems, are often expressed in terms of global-mean temperature . The rate of climate change over multi-decadal scales is also important, with faster rates of change resulting in less time for human and natural systems to adapt . We find that current trends in greenhouse gas and aerosol emissions are now moving the Earth system into a regime in terms of multi-decadal rates of change that are unprecedented for at least the last 1000 years. The rate of global-mean temperature increase in the CMIP5 archive over 40-year periods increases to 0.25±0.05 (1σ) °C per decade by 2020, an average greater than peak rates of change during the previous 1-2 millennia. Regional rates of change in Europe, North America and the Arctic are higher than the global average. Research on the impacts of such near-term rates of change is urgently needed.

  6. Non-accelerating wage inflation rate of unemployment in Poland

    Katarzyna Budnik

    2008-01-01

    The model of the wage bargaining constitutes a framework for calculation of the NAWRU in Poland. The approach used in the paper let me trace changes of the natural unemployment rate in Poland in the context of structural changes in the economy in the last decade. Moreover, I introduced the endogenous equilibrium rate into the existing macroeconomic model — ECMOD. It allowed me to simulate NAWRU behavior after economic shocks. Simulation results shed some light on channels and speed of adjustm...

  7. STATISTICAL INFERENCE OF WEIBULL DISTRIBUTION FOR TAMPERED FAILURE RATE MODEL IN PROGRESSIVE STRESS ACCELERATED LIFE TESTING

    WANG Ronghua; FEI Heliang

    2004-01-01

    In this note, the tampered failure rate model is generalized from the step-stress accelerated life testing setting to the progressive stress accelerated life testing for the first time. For the parametric setting where the scale parameter satisfying the equation of the inverse power law is Weibull, maximum likelihood estimation is investigated.

  8. Dynamic evolutionary change in post-Paleozoic echinoids and the importance of scale when interpreting changes in rates of evolution

    Hopkins, Melanie J.; Smith, Andrew B.

    2015-03-01

    How ecological and morphological diversity accrues over geological time has been much debated by paleobiologists. Evidence from the fossil record suggests that many clades reach maximal diversity early in their evolutionary history, followed by a decline in evolutionary rates as ecological space fills or due to internal constraints. Here, we apply recently developed methods for estimating rates of morphological evolution during the post-Paleozoic history of a major invertebrate clade, the Echinoidea. Contrary to expectation, rates of evolution were lowest during the initial phase of diversification following the Permo-Triassic mass extinction and increased over time. Furthermore, although several subclades show high initial rates and net decreases in rates of evolution, consistent with "early bursts" of morphological diversification, at more inclusive taxonomic levels, these bursts appear as episodic peaks. Peak rates coincided with major shifts in ecological morphology, primarily associated with innovations in feeding strategies. Despite having similar numbers of species in today's oceans, regular echinoids have accrued far less morphological diversity than irregular echinoids due to lower intrinsic rates of morphological evolution and less morphological innovation, the latter indicative of constrained or bounded evolution. These results indicate that rates of evolution are extremely heterogenous through time and their interpretation depends on the temporal and taxonomic scale of analysis.

  9. Does hybridization increase evolutionary rate? Data from the 28S-rDNA D8 domain in echinoderms.

    Chenuil, Anne; Egea, Emilie; Rocher, Caroline; Touzet, Hélène; Féral, Jean-Pierre

    2008-11-01

    The divergent domain D8 of the large ribosomal RNA is very variable and extended in vertebrates compared to other eukaryotes. We provide data from 31 species of echinoderms and present the first comparative analysis of the D8 in nonvertebrate deuterostomes. In addition, we obtained 16S mitochondrial DNA sequences for the sea urchin taxa and analyzed single-strand conformation polymorphism (SSCP) of D8 in several populations within the species complex Echinocardium cordatum. A common secondary structure supported by compensatory substitutions and indels is inferred for echinoderms. Variation mostly arises at the tip of the longest stem (D8a), and the most variable taxa also display the longest and most stable D8. The most stable variants are the only ones displaying bulges in the terminal part of the stem, suggesting that selection, rather than maximizing stability of the D8 secondary structure, maintains it in a given range. Striking variation in D8 evolutionary rates was evidenced among sea urchins, by comparison with both 16S mitochondrial DNA and paleontological data. In Echinocardium cordatum and Strongylocentrotus pallidus and S. droebachiensis, belonging to very distant genera, the increase in D8 evolutionary rate is extreme. Their highly stable D8 secondary structures rule out the possibility of pseudogenes. These taxa are the only ones in which interspecific hybridization was reported. We discuss how evolutionary rates may be affected in nuclear relative to mitochondrial genes after hybridization, by selective or mutational processes such as gene silencing and concerted evolution. PMID:18949506

  10. Effect of acceleration of the decay rate of 198Au: a preliminary report

    Experimental evidence obtained at the Los Alamos National Laboratory during 1980 suggests that the decay rate of 198Au may be influenced to a measurable extent by acceleration of the bulk material. In the experiments, a sample of 198Au was subjected to a sustained acceleration of approximately 196,000 g's, and its decay rate was compared with that of a control sample that remained at rest. The decay probability of the accelerated sample was observed to exceed that of the control sample by 7.48 standard deviations. This was the maximum value resulting from comparison of the accelerated sample data and the control sample data. Although not conclusive, these preliminary data are certainly suggestive that a direct coupling may exist between gravitation (acceleration) and nuclear processes

  11. Evolutionary determination of kinetic Monte Carlo rates for the simulation of evolving surfaces in anisotropic etching of silicon

    This study explores for the first time the possibility of using an evolutionary algorithm (EA) for the determination of atomistic rates for use in kinetic Monte Carlo (KMC) simulations of anisotropic etching of silicon for the manufacture of microelectromechanical systems (MEMS). Traditionally, KMC rates are determined based on (i) computationally expensive density functional theory (DFT) calculations or, when possible, (ii) a combination of physical insight and a labor-intensive, manual procedure where, e.g., experimental and simulated surface morphologies are visually matched for a collection of surface orientations. Compared to these approaches, the evolutionary KMC method proposed in this study provides a more flexible, autonomous procedure to describe correctly a wide variety of etching conditions. We focus on the use of a functional representation of the atomistic rates, referred to as the removal probability function (RPF). This simplifies the EA search space to just a few parameters and reduces the number of required experimental data points to just a few etch rates. By proposing two alternative RPFs with four and six parameters, respectively, we show that the ability to explain the orientation dependence of the etch rate for a wide variety of etchants increases with the number of parameters and conclude that the six-parameter RPF provides sufficiently good simulations for a wide range of etching conditions, including KOH, KOH+IPA, TMAH and TMAH+Triton at different concentrations and temperatures. By uncovering the relationships between the parameters and the concentration of the etchant, it is possible to extend the simulations to nonmeasured etching conditions. Although the use of an RPF effectively restricts the search to a subspace of the atomistic rates, the present results suggest that physically meaningful KMC rates can probably be determined in the near future by direct comparison of macroscopic experiments and simulations through the use of

  12. Evolutionary determination of kinetic Monte Carlo rates for the simulation of evolving surfaces in anisotropic etching of silicon

    Xing, Y.; Gosálvez, M. A.; Sato, K.; Tian, M.; Yi, H.

    2012-08-01

    This study explores for the first time the possibility of using an evolutionary algorithm (EA) for the determination of atomistic rates for use in kinetic Monte Carlo (KMC) simulations of anisotropic etching of silicon for the manufacture of microelectromechanical systems (MEMS). Traditionally, KMC rates are determined based on (i) computationally expensive density functional theory (DFT) calculations or, when possible, (ii) a combination of physical insight and a labor-intensive, manual procedure where, e.g., experimental and simulated surface morphologies are visually matched for a collection of surface orientations. Compared to these approaches, the evolutionary KMC method proposed in this study provides a more flexible, autonomous procedure to describe correctly a wide variety of etching conditions. We focus on the use of a functional representation of the atomistic rates, referred to as the removal probability function (RPF). This simplifies the EA search space to just a few parameters and reduces the number of required experimental data points to just a few etch rates. By proposing two alternative RPFs with four and six parameters, respectively, we show that the ability to explain the orientation dependence of the etch rate for a wide variety of etchants increases with the number of parameters and conclude that the six-parameter RPF provides sufficiently good simulations for a wide range of etching conditions, including KOH, KOH+IPA, TMAH and TMAH+Triton at different concentrations and temperatures. By uncovering the relationships between the parameters and the concentration of the etchant, it is possible to extend the simulations to nonmeasured etching conditions. Although the use of an RPF effectively restricts the search to a subspace of the atomistic rates, the present results suggest that physically meaningful KMC rates can probably be determined in the near future by direct comparison of macroscopic experiments and simulations through the use of

  13. Assessing the evolutionary rate of positional orthologous genes in prokaryotes using synteny data

    Lespinet Olivier

    2007-11-01

    Full Text Available Abstract Background Comparison of completely sequenced microbial genomes has revealed how fluid these genomes are. Detecting synteny blocks requires reliable methods to determining the orthologs among the whole set of homologs detected by exhaustive comparisons between each pair of completely sequenced genomes. This is a complex and difficult problem in the field of comparative genomics but will help to better understand the way prokaryotic genomes are evolving. Results We have developed a suite of programs that automate three essential steps to study conservation of gene order, and validated them with a set of 107 bacteria and archaea that cover the majority of the prokaryotic taxonomic space. We identified the whole set of shared homologs between two or more species and computed the evolutionary distance separating each pair of homologs. We applied two strategies to extract from the set of homologs a collection of valid orthologs shared by at least two genomes. The first computes the Reciprocal Smallest Distance (RSD using the PAM distances separating pairs of homologs. The second method groups homologs in families and reconstructs each family's evolutionary tree, distinguishing bona fide orthologs as well as paralogs created after the last speciation event. Although the phylogenetic tree method often succeeds where RSD fails, the reverse could occasionally be true. Accordingly, we used the data obtained with either methods or their intersection to number the orthologs that are adjacent in for each pair of genomes, the Positional Orthologous Genes (POGs, and to further study their properties. Once all these synteny blocks have been detected, we showed that POGs are subject to more evolutionary constraints than orthologs outside synteny groups, whichever the taxonomic distance separating the compared organisms. Conclusion The suite of programs described in this paper allows a reliable detection of orthologs and is useful for evaluating gene

  14. Increased rate of acceleration on Pine Island Glacier strongly coupled to changes in gravitational driving stress

    J. B. T. Scott

    2009-05-01

    Full Text Available Pine Island Glacier, Antarctica, has been undergoing several related changes for at least two decades; these include acceleration, thinning and grounding line retreat. During the first major ground-based study between 2006 and 2008, GPS receivers were used to monitor ice flow from 55 km to 171 km inland, along the central flowline. At four sites both acceleration and thinning rates over the last two years exceeded rates observed at any other time over the last two decades. At the downstream site acceleration was 6.4% over 2007 and thinning was 3.5±0.5 ma−1. Acceleration and thinning have spread rapidly inland with the acceleration 171 km inland at 4.1% over 2007, greater than any measured annual flow increase along the whole glacier prior to 2006. Increases in surface slope, and hence gravitational driving stress, correlate well with the acceleration and no sustained change in longitudinal stress gradient is needed to explain the force balance. There is no indication that the glacier is approaching a new steady state.

  15. Accelerator

    The invention claims equipment for stabilizing the position of the front covers of the accelerator chamber in cyclic accelerators which significantly increases accelerator reliability. For stabilizing, it uses hydraulic cushions placed between the electromagnet pole pieces and the front chamber covers. The top and the bottom cushions are hydraulically connected. The cushions are disconnected and removed from the hydraulic line using valves. (J.P.)

  16. Testing for natural selection in human exonic splicing regulators associated with evolutionary rate shifts.

    Ramalho, Rodrigo F; Gelfman, Sahar; de Souza, Jorge E; Ast, Gil; de Souza, Sandro J; Meyer, Diogo

    2013-04-01

    Despite evidence that at the interspecific scale, exonic splicing silencers (ESSs) are under negative selection in constitutive exons, little is known about the effects of slightly deleterious polymorphisms on these splicing regulators. Through the application of a modified version of the McDonald-Kreitman test, we compared the normalized proportions of human polymorphisms and human/rhesus substitutions affecting exonic splicing regulators (ESRs) on sequences of constitutive and alternative exons. Our results show a depletion of substitutions and an enrichment of SNPs associated with ESS gain in constitutive exons. Moreover, we show that this evolutionary pattern is also present in a set of ESRs previously involved in the transition from constitutive to skipped exons in the mammalian lineage. The similarity between these two sets of ESRs suggests that the transition from constitutive to skipped exons in mammals is more frequently associated with the inhibition than with the promotion of splicing signals. This is in accordance with the hypothesis of a constitutive origin of exon skipping and corroborates previous findings about the antagonistic role of certain exonic splicing enhancers. PMID:23529588

  17. Transcriptomics and molecular evolutionary rate analysis of the bladderwort (Utricularia, a carnivorous plant with a minimal genome

    Herrera-Estrella Alfredo

    2011-06-01

    Full Text Available Abstract Background The carnivorous plant Utricularia gibba (bladderwort is remarkable in having a minute genome, which at ca. 80 megabases is approximately half that of Arabidopsis. Bladderworts show an incredible diversity of forms surrounding a defined theme: tiny, bladder-like suction traps on terrestrial, epiphytic, or aquatic plants with a diversity of unusual vegetative forms. Utricularia plants, which are rootless, are also anomalous in physiological features (respiration and carbon distribution, and highly enhanced molecular evolutionary rates in chloroplast, mitochondrial and nuclear ribosomal sequences. Despite great interest in the genus, no genomic resources exist for Utricularia, and the substitution rate increase has received limited study. Results Here we describe the sequencing and analysis of the Utricularia gibba transcriptome. Three different organs were surveyed, the traps, the vegetative shoot bodies, and the inflorescence stems. We also examined the bladderwort transcriptome under diverse stress conditions. We detail aspects of functional classification, tissue similarity, nitrogen and phosphorus metabolism, respiration, DNA repair, and detoxification of reactive oxygen species (ROS. Long contigs of plastid and mitochondrial genomes, as well as sequences for 100 individual nuclear genes, were compared with those of other plants to better establish information on molecular evolutionary rates. Conclusion The Utricularia transcriptome provides a detailed genomic window into processes occurring in a carnivorous plant. It contains a deep representation of the complex metabolic pathways that characterize a putative minimal plant genome, permitting its use as a source of genomic information to explore the structural, functional, and evolutionary diversity of the genus. Vegetative shoots and traps are the most similar organs by functional classification of their transcriptome, the traps expressing hydrolytic enzymes for prey

  18. Evolutionary Game-Based Secrecy Rate Adaptation in Wireless Sensor Networks

    2015-01-01

    Physical layer security, whose aim is to maximize the secrecy rate of a source while keeping eavesdroppers ignorant of data transmitted, is extremely suitable for Wireless Sensor Networks (WSNs). We therefore, by developing the classical wire-tap channel, construct an approach to compute the secrecy rate between a sensor node and its responsible cluster head in the clustered WSNs. A noncooperative secrecy rate game towards WSNs is formulated to solve contradictions between maximizing the secr...

  19. Evolution of high-repetition-rate induction accelerators through advancements in switching

    Future applications of linear and recirculating induction accelerators include microwave sources for plasma heating and linear colliders, industrial manufacturing processes, and heavy-ion fusion. These applications require pulsed sources capable of sustained operation at high pulse-repetition rates. Powering these new accelerators places severe switching demands on the source that often can not be met with commercially-available technology. Consequently, several new accelerator switching schemes have been developed at Lawrence Livermore National Laboratory. Our transition from spark-gap technology to magnetic switching has merged the formerly independent roles of source and cell into a single system and reshaped our design methods to emphasize high efficiency. Treatment of the accelerator as a system has also enabled us to optimize new accelerator designs based on cost considerations. Presently, we are developing a technology for driving a heavy-ion induction recirculator at pulse rates exceeding 100 kHz. In this case, the switching method is all solid state and the source and cell have evolved into unified device. (Author) 6 figs., tab., 30 refs

  20. Controlling for Phylogenetic Relatedness and Evolutionary Rates Improves the Discovery of Associations Between Species’ Phenotypic and Genomic Differences

    Prudent, Xavier; Parra, Genis; Schwede, Peter; Roscito, Juliana G.; Hiller, Michael

    2016-01-01

    The growing number of sequenced genomes allows us now to address a key question in genetics and evolutionary biology: which genomic changes underlie particular phenotypic changes between species? Previously, we developed a computational framework called Forward Genomics that associates phenotypic to genomic differences by focusing on phenotypes that are independently lost in different lineages. However, our previous implementation had three main limitations. Here, we present two new Forward Genomics methods that overcome these limitations by (1) directly controlling for phylogenetic relatedness, (2) controlling for differences in evolutionary rates, and (3) computing a statistical significance. We demonstrate on large-scale simulated data and on real data that both new methods substantially improve the sensitivity to detect associations between phenotypic and genomic differences. We applied these new methods to detect genomic differences involved in the loss of vision in the blind mole rat and the cape golden mole, two independent subterranean mammals. Forward Genomics identified several genes that are enriched in functions related to eye development and the perception of light, as well as genes involved in the circadian rhythm. These new Forward Genomics methods represent a significant advance in our ability to discover the genomic basis underlying phenotypic differences between species. Source code: https://github.com/hillerlab/ForwardGenomics/ PMID:27222536

  1. Using rules to adapt applications for business models with high evolutionary rates

    Juan Fuente, A. A

    2013-06-01

    Full Text Available Nowadays, business models are in permanent evolution since the requirements belongs to a rapidly evolving world. In a context where communications all around the world travel so fast the business models need to be adapted permanently to the information the managers receive. In such world, traditional software development, needed for adapting software to changes, do not work properly since business changes need to be in exploitation in shorter times. In that situation, it is needed to go quicker from the business idea to the exploitation environment. This issue can be solved accelerating the development speed: from the expert to the customer, with no –or few, technical intervention. This paper proposes an approach to empower domain experts in developing adaptability solutions by using automated sets of production rules in a friendly way. Furthermore, a use case that implements this kind of development was used in a real problem prototype.

  2. Charge Accretion Rate and Injection Radius of Ionized-Induced Injections in Laser Wakefield Accelerators

    Zeng, Ming; Chen, Min; Sheng, Zheng-Ming

    2016-03-01

    Ionization-induced injection has recently been proved to be a stable injection method with several advantages in laser wakefield accelerators. However, the controlling of this injection process aiming at producing high quality electron beams is still challenging. In this paper, we examine the ionization injection processes and estimate the injection rate with two-dimensional particle-in-cell simulations. The injection rate is shown to increase linearly with the high-Z gas density as long as its ratio is smaller than some threshold in the mix gases. It is also shown that by changing the transverse mode of the driving lasers one can control the injection rate.

  3. Gamma-limits and relaxations for rate-independent evolutionary problems

    Mielke, A.; Roubíček, Tomáš; Stefannelli, U.

    2008-01-01

    Roč. 3, č. 31 (2008), s. 387-416. ISSN 0944-2669 Grant ostatní: GA MŠk(CZ) LC06052 Institutional research plan: CEZ:AV0Z10750506 Keywords : Rate-independent problems * energetic formulation * Gamma convergence * relaxation * time-incremental minimization Subject RIV: BA - General Mathematics Impact factor: 0.912, year: 2008

  4. Extinction of fish-shaped marine reptiles associated with reduced evolutionary rates and global environmental volatility.

    Fischer, Valentin; Bardet, Nathalie; Benson, Roger B J; Arkhangelsky, Maxim S; Friedman, Matt

    2016-01-01

    Despite their profound adaptations to the aquatic realm and their apparent success throughout the Triassic and the Jurassic, ichthyosaurs became extinct roughly 30 million years before the end-Cretaceous mass extinction. Current hypotheses for this early demise involve relatively minor biotic events, but are at odds with recent understanding of the ichthyosaur fossil record. Here, we show that ichthyosaurs maintained high but diminishing richness and disparity throughout the Early Cretaceous. The last ichthyosaurs are characterized by reduced rates of origination and phenotypic evolution and their elevated extinction rates correlate with increased environmental volatility. In addition, we find that ichthyosaurs suffered from a profound Early Cenomanian extinction that reduced their ecological diversity, likely contributing to their final extinction at the end of the Cenomanian. Our results support a growing body of evidence revealing that global environmental change resulted in a major, temporally staggered turnover event that profoundly reorganized marine ecosystems during the Cenomanian. PMID:26953824

  5. Optimisation Studies of Accelerator Driven Fertile to Fissile Conversion Rates in Thorium Fuel Cycle

    Bungau, Cristian; Barlow, Roger; Cywinski, R.

    2012-01-01

    The need for proliferation-resistance, longer fuel cycles, higher burn up and improvedwaste form characteristics has led to a renewed worldwide interest in thorium-based fuels and fuel cycles. In this paper the GEANT4 Monte Carlo code has been used to simulate the Thorium-Uranium fuel cycle. The accelerator driven fertile to fissile conversion rates have been calculated for various geometries. Several new classes have been added by the authors to the GEANT4 simulation ...

  6. Developing a Corticopuncture system to accelerate the rate of tooth movement

    Mostafa, Mohamed Moharam

    2014-01-01

    Introduction:Tooth movement is caused by inflammatory and cellular reactions within the bone in response to applied orthodontic forces. Several attempts have been made to increase the rate of bone turnover in order to achieve accelerated tooth movement. These attempts can be classified into two categories: physical trauma (such as Alveolar Corticotomy "Wilckodontics", Piezopuncture, Laser and Resonance Vibrations) and application of drugs (such as the systemic and local application of Vitami...

  7. Bayesian coalescent inference reveals high evolutionary rates and diversification of Zika virus populations.

    Fajardo, Alvaro; Soñora, Martín; Moreno, Pilar; Moratorio, Gonzalo; Cristina, Juan

    2016-10-01

    Zika virus (ZIKV) is a member of the family Flaviviridae. In 2015, ZIKV triggered an epidemic in Brazil and spread across Latin America. By May of 2016, the World Health Organization warns over spread of ZIKV beyond this region. Detailed studies on the mode of evolution of ZIKV strains are extremely important for our understanding of the emergence and spread of ZIKV populations. In order to gain insight into these matters, a Bayesian coalescent Markov Chain Monte Carlo analysis of complete genome sequences of recently isolated ZIKV strains was performed. The results of these studies revealed a mean rate of evolution of 1.20 × 10(-3) nucleotide substitutions per site per year (s/s/y) for ZIKV strains enrolled in this study. Several variants isolated in China are grouped together with all strains isolated in Latin America. Another genetic group composed exclusively by Chinese strains were also observed, suggesting the co-circulation of different genetic lineages in China. These findings indicate a high level of diversification of ZIKV populations. Strains isolated from microcephaly cases do not share amino acid substitutions, suggesting that other factors besides viral genetic differences may play a role for the proposed pathogenesis caused by ZIKV infection. J. Med. Virol. 88:1672-1676, 2016. © 2016 Wiley Periodicals, Inc. PMID:27278855

  8. Changes in growth rates of oral jaw elements produce evolutionary novelty in bahamian pupfish.

    Lencer, Ezra S; Riccio, Mark L; McCune, Amy R

    2016-07-01

    To understand the origins of novelty and the evolution of biological diversity, it is important to investigate the processes that generate phenotypic variation from genotypic variation. A number of path-breaking studies have revealed the genetic basis for phenotypic differences between distantly related taxa, but how qualitative change is produced during the early stages of divergence is largely unexplored. Here, we focus on striking differences in jaw morphology exhibited by three closely related sympatric pupfish species (genus Cyprinodon) from San Salvador Island, Bahamas as a basis for investigating the genetic sources of morphological variation in recently diverged species. San Salvador Island pupfish are trophically diverse and display derived jaw morphologies distinct from any other species in the genus. We illustrate these qualitative morphological differences between species with 3D-reconstructed CT-images and camera lucida drawings of the skulls of wild-caught fish. Quantitative data representing the size of individual bony skull elements in wild fish show how qualitatively novel morphologies arise as a consequence of changes to the size and shape of individual skull elements, particularly the dentary, premaxilla, and maxilla bones associated with the oral jaws. Consistent with these comparative data is that the growth rate of individual bony skull elements, measured on a developmental time series of lab-reared fish, differs between species. Our data provide a critical foundation for future studies developing San Salvador Cyprinodon pupfishes as a model system to understand the evolution and development of novel morphologies at the species level. J. Morphol. 277:935-947, 2016. © 2016 Wiley Periodicals, Inc. PMID:27103074

  9. Influence of ethanol-amine injection on flow accelerated corrosion rate in pressurized water reactor

    Some pressurized water reactor (PWR) plants have introduced ethanol-amine (ETA) injection for the purpose of decreasing iron transfer in the steam generator (SG). The ETA injection is supposed to decrease the rate of flow accelerated corrosion (FAC) by increasing the pH of the secondary system. However, the water chemistry in the secondary system is very complicated and so water chemistry following ETA injection and the effect of ETA injection on FAC rate have not been studied systematically. To assess the influence of ETA injection on FAC rate, we use a model that assumes the FAC rate is proportional to the concentration gradient of magnetite. We then calculate the chemical concentration and magnetite solubility of the secondary system and approximately evaluate the change of FAC rate. It is shown that ETA injection reduces the FAC rate to about 1/3 - 1/22 of that of ammonia. In some portions of the secondary system, we also measured the effects of ETA injection experimentally by rotating disk test, and found that the FAC rate decreases under ETA conditions. The peak FAC rate shifted to a higher temperature after ETA injection. At 274degC, the FAC rates are nearly the same under the conditions of high pH of ETA and low pH of ammonia. (author)

  10. Error-Rate Estimation Based on Multi-Signal Flow Graph Model and Accelerated Radiation Tests.

    He, Wei; Wang, Yueke; Xing, Kefei; Deng, Wei; Zhang, Zelong

    2016-01-01

    A method of evaluating the single-event effect soft-error vulnerability of space instruments before launched has been an active research topic in recent years. In this paper, a multi-signal flow graph model is introduced to analyze the fault diagnosis and meantime to failure (MTTF) for space instruments. A model for the system functional error rate (SFER) is proposed. In addition, an experimental method and accelerated radiation testing system for a signal processing platform based on the field programmable gate array (FPGA) is presented. Based on experimental results of different ions (O, Si, Cl, Ti) under the HI-13 Tandem Accelerator, the SFER of the signal processing platform is approximately 10-3(error/particle/cm2), while the MTTF is approximately 110.7 h. PMID:27583533

  11. Influence of ethanol-amine injection on flow accelerated corrosion rate in pressurized water reactor

    Some pressurized water reactor (PWR) plants have introduced ethanol-amine (ETA) injection for the purpose of decreasing iron transfer in steam generator (SG). The ETA injection is supposed to decrease flow accelerated corrosion (FAC) rate, because of secondary system pH increase. But the water chemistry in the secondary system is very complicated. So water chemistry following ETA injection and the effect of ETA injection on FAC rate have not been studied systematically. To assess the influence of ETA injection on FAC rate, it is assumed that the model of FAC rate is proportional to the concentration gradient of magnetite. Then chemical concentration and magnetite solubility of the secondary system are calculated and the change of FAC rate is evaluated in the outline. It has been clarified that the effect of ETA injection reduces the FAC rate to about 1/3-1/22 of that of ammonia. In some portions of the secondary system, the effects of ETA injection have been measured experimentally by rotary disk test. The FAC rate of ETA injection is larger than that of ammonia at high temperature. And the FAC rate peaks at about 180degC in the case of ammonia, but the peak seems to shift to higher temperatures in the case of ETA. (author)

  12. Residue Geometry Networks: A Rigidity-Based Approach to the Amino Acid Network and Evolutionary Rate Analysis.

    Fokas, Alexander S; Cole, Daniel J; Ahnert, Sebastian E; Chin, Alex W

    2016-01-01

    Amino acid networks (AANs) abstract the protein structure by recording the amino acid contacts and can provide insight into protein function. Herein, we describe a novel AAN construction technique that employs the rigidity analysis tool, FIRST, to build the AAN, which we refer to as the residue geometry network (RGN). We show that this new construction can be combined with network theory methods to include the effects of allowed conformal motions and local chemical environments. Importantly, this is done without costly molecular dynamics simulations required by other AAN-related methods, which allows us to analyse large proteins and/or data sets. We have calculated the centrality of the residues belonging to 795 proteins. The results display a strong, negative correlation between residue centrality and the evolutionary rate. Furthermore, among residues with high closeness, those with low degree were particularly strongly conserved. Random walk simulations using the RGN were also successful in identifying allosteric residues in proteins involved in GPCR signalling. The dynamic function of these residues largely remain hidden in the traditional distance-cutoff construction technique. Despite being constructed from only the crystal structure, the results in this paper suggests that the RGN can identify residues that fulfil a dynamical function. PMID:27623708

  13. Effects of local flow field on flow accelerated corrosion. Wall thinning rate at elbow pipe

    In order to evaluate the effects of a flow field on wall thinning rate due to flow accelerated corrosion (FAC), the authors have carried out wall thinning rate measurements using the electrical resistance method, measurements of the velocity profile, and numerical simulation for each piping component such as an orifice and a globe valve. In this study, wall thinning rates were measured were conducted at an elbow pipe without the orifice. In the wall thinning rate measurement, a test loop operated at high temperature and high pressure conditions was used. The pipe inner diameter was 50mm, and the average velocity was changed during the experiment from 6.22m/s to 4.98m/s. The water temperature was controlled within 150±1degC. The wall thinning rates in the elbow pipe were larger than those upstream and downstream from the elbow pipe. The distribution of wall thinning rates in the elbow pipe was asymmetrical to the center axis in the circumferential direction of the pipe, and the wall thinning rate at the extrados of the elbow pipe was larger than that at intrados. (author)

  14. Accelerating regional atrophy rates in the progression from normal aging to Alzheimer's disease

    Sluimer, Jasper D. [VU University Medical Centre, Department of Diagnostic Radiology, Amsterdam (Netherlands); VU University Medical Centre, Alzheimer Centre, Amsterdam (Netherlands); VU University Medical Centre, Image Analysis Centre, Amsterdam (Netherlands); VU University Medical Centre, Department of Diagnostic Radiology and Alzheimer Centre, PO Box 7057, Amsterdam (Netherlands); Flier, Wiesje M. van der; Scheltens, Philip [VU University Medical Centre, Alzheimer Centre, Amsterdam (Netherlands); VU University Medical Centre, Department of Neurology, Amsterdam (Netherlands); Karas, Giorgos B.; Barkhof, Frederik [VU University Medical Centre, Department of Diagnostic Radiology, Amsterdam (Netherlands); VU University Medical Centre, Alzheimer Centre, Amsterdam (Netherlands); VU University Medical Centre, Image Analysis Centre, Amsterdam (Netherlands); Schijndel, Ronald van [VU University Medical Centre, Image Analysis Centre, Amsterdam (Netherlands); VU University Medical Centre, Department of Informatics, Amsterdam (Netherlands); Barnes, Josephine; Boyes, Richard G. [UCL, Institute of Neurology, Dementia Research Centre, London (United Kingdom); Cover, Keith S. [VU University Medical Centre, Department of Physics and Medical Technology, Amsterdam (Netherlands); Olabarriaga, Silvia D. [University of Amsterdam, Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Centre, Amsterdam (Netherlands); Fox, Nick C. [VU University Medical Centre, Department of Neurology, Amsterdam (Netherlands); UCL, Institute of Neurology, Dementia Research Centre, London (United Kingdom); Vrenken, Hugo [VU University Medical Centre, Alzheimer Centre, Amsterdam (Netherlands); VU University Medical Centre, Image Analysis Centre, Amsterdam (Netherlands); VU University Medical Centre, Department of Physics and Medical Technology, Amsterdam (Netherlands)

    2009-12-15

    We investigated progression of atrophy in vivo, in Alzheimer's disease (AD), and mild cognitive impairment (MCI). We included 64 patients with AD, 44 with MCI and 34 controls with serial MRI examinations (interval 1.8 {+-} 0.7 years). A nonlinear registration algorithm (fluid) was used to calculate atrophy rates in six regions: frontal, medial temporal, temporal (extramedial), parietal, occipital lobes and insular cortex. In MCI, the highest atrophy rate was observed in the medial temporal lobe, comparable with AD. AD patients showed even higher atrophy rates in the extramedial temporal lobe. Additionally, atrophy rates in frontal, parietal and occipital lobes were increased. Cox proportional hazard models showed that all regional atrophy rates predicted conversion to AD. Hazard ratios varied between 2.6 (95% confidence interval (CI) = 1.1-6.2) for occipital atrophy and 15.8 (95% CI = 3.5-71.8) for medial temporal lobe atrophy. In conclusion, atrophy spreads through the brain with development of AD. MCI is marked by temporal lobe atrophy. In AD, atrophy rate in the extramedial temporal lobe was even higher. Moreover, atrophy rates also accelerated in parietal, frontal, insular and occipital lobes. Finally, in nondemented elderly, medial temporal lobe atrophy was most predictive of progression to AD, demonstrating the involvement of this region in the development of AD. (orig.)

  15. Accelerating regional atrophy rates in the progression from normal aging to Alzheimer's disease

    We investigated progression of atrophy in vivo, in Alzheimer's disease (AD), and mild cognitive impairment (MCI). We included 64 patients with AD, 44 with MCI and 34 controls with serial MRI examinations (interval 1.8 ± 0.7 years). A nonlinear registration algorithm (fluid) was used to calculate atrophy rates in six regions: frontal, medial temporal, temporal (extramedial), parietal, occipital lobes and insular cortex. In MCI, the highest atrophy rate was observed in the medial temporal lobe, comparable with AD. AD patients showed even higher atrophy rates in the extramedial temporal lobe. Additionally, atrophy rates in frontal, parietal and occipital lobes were increased. Cox proportional hazard models showed that all regional atrophy rates predicted conversion to AD. Hazard ratios varied between 2.6 (95% confidence interval (CI) = 1.1-6.2) for occipital atrophy and 15.8 (95% CI = 3.5-71.8) for medial temporal lobe atrophy. In conclusion, atrophy spreads through the brain with development of AD. MCI is marked by temporal lobe atrophy. In AD, atrophy rate in the extramedial temporal lobe was even higher. Moreover, atrophy rates also accelerated in parietal, frontal, insular and occipital lobes. Finally, in nondemented elderly, medial temporal lobe atrophy was most predictive of progression to AD, demonstrating the involvement of this region in the development of AD. (orig.)

  16. Reverse and Forward Shock X-ray Emission in an Evolutionary Model of Supernova Remnants undergoing Efficient Diffusive Shock Acceleration

    Lee, Shiu-Hang; Ellison, Donald C; Nagataki, Shigehiro; Slane, Patrick O

    2014-01-01

    We present new models for the forward and reverse shock thermal X-ray emission from core-collapse and Type Ia supernova remnants (SNRs) which include the efficient production of cosmic rays via non-linear diffusive shock acceleration (DSA). Our CR-hydro-NEI code takes into account non-equilibrium ionization (NEI), hydrodynamic effects of efficient CR production on the SNR evolution, and collisional temperature equilibration among heavy ions and electrons in both the shocked supernova (SN) ejecta and the shocked circumstellar material. While X-ray emission is emphasized here, our code self-consistently determines both thermal and non-thermal broadband emission from radio to TeV energies. We include Doppler broadening of the spectral lines by thermal motions of the ions and by the remnant expansion. We study, in general terms, the roles which the ambient environment, progenitor models, temperature equilibration, and processes related to DSA have on the thermal and non-thermal spectra. The study of X-ray line em...

  17. Flow accelerated corrosion and mass transfer rate in orifice downstream flow

    Flow Accelerated Corrosion (FAC) is one of the issues to be noticed considerably in plant piping management. For the integrity and safety of the plant, the wall-thinning and thinning rate due to FAC should be clearly predicted in pipe wall inspection. In this paper, we study FAC from the view point of flow dynamics. The mass transfer coefficient is measured by the electrochemical method behind the orifice. Changing the orifice size, the peak location of mass transfer coefficient and its maximum value is evaluated by the flow condition and orifice parameter. (author)

  18. Reverse and forward shock X-ray emission in an evolutionary model of supernova remnants undergoing efficient diffusive shock acceleration

    We present new models for the forward and reverse shock thermal X-ray emission from core-collapse and Type Ia supernova remnants (SNRs) that include the efficient production of cosmic rays (CR) via nonlinear diffusive shock acceleration (DSA). Our CR-hydro-NEI code takes into account non-equilibrium ionization, hydrodynamic effects of efficient CR production on the SNR evolution, and collisional temperature equilibration among heavy ions and electrons in both the shocked supernova (SN) ejecta and the shocked circumstellar material. While X-ray emission is emphasized here, our code self-consistently determines both thermal and non-thermal broadband emission from radio to TeV energies. We include Doppler broadening of the spectral lines by thermal motions of the ions and by the remnant expansion. We study, in general terms, the roles that the ambient environment, progenitor models, temperature equilibration, and processes related to DSA have on the thermal and non-thermal spectra. The study of X-ray line emission from young SNRs is a powerful tool for determining specific SN elemental contributions and for providing critical information that helps to understand the type and energetics of the explosion, the composition of the ambient medium in which the SN exploded, and the ionization and dynamics of the hot plasma in the shocked SN ejecta and interstellar medium. With the approaching launch of the next-generation X-ray satellite Astro-H, observations of spectral lines with unprecedented high resolution will become a reality. Our self-consistent calculations of the X-ray spectra from various progenitors will help interpret future observations of SNRs.

  19. Reaction Rate Acceleration and Tg Depression of Polycyanurate Under Nanopore Confinement

    Lopez, Evelyn; Simon, Sindee L.

    2015-03-01

    Material properties such as Tg and the reaction kinetics are known to deviate from the bulk when subjected to nano-sized confinement. Previous work from our laboratory on the trimerization of cyanate esters found that the reaction kinetics were faster for a monofunctional reactant compared to a difunctional monomer, whereas the Tg depression was greater for the crosslinked product of the latter compared to the low molecular weight trimer of the former. The origin of the changes in nanoconfined reaction rates differs from those that govern changes in the Tg. The research objective is to further explore the effect that confinement has on reaction kinetics and Tg using a mixture consisting of mono- and di- cyanate ester monomers. The product is an uncrosslinked polycyanurate with Mn = 5240 g/mol and PDI = 1.78. The confinement mediums are controlled pore glasses with diameters ranging from 8.1 to 111.1 nm. The nanopore-confined material was synthesized in-situ and the reaction kinetics are followed by DSC; after the reaction, the Tg values of the nanoconfined polymer where also measured by DSC. An acceleration factor of 13 and a Tg depression of 38 °C are observed for the material confined in the smallest 8.1 nm-diameter pores. The Tg depression is between those of the trimer and network previously studied, while the acceleration of the reaction rate is lower. Our results are consistent with the reaction acceleration arising from packing effects at the pore wall and the Tg depression arising from intrinsic size effects.

  20. Multi-Pulse Laser Wakefield Acceleration: A New Route to Efficient, High-Repetition-Rate Plasma Accelerators and High Flux Radiation Sources

    Hooker, S M; Mangles, S P D; Tünnermann, A; Corner, L; Limpert, J; Seryi, A; Walczak, R

    2014-01-01

    Laser-driven plasma accelerators can generate accelerating gradients three orders of magnitude larger than radio-frequency accelerators and have achieved beam energies above 1 GeV in centimetre long stages. However, the pulse repetition rate and wall-plug efficiency of plasma accelerators is limited by the driving laser to less than approximately 1 Hz and 0.1% respectively. Here we investigate the prospects for exciting the plasma wave with trains of low-energy laser pulses rather than a single high-energy pulse. Resonantly exciting the wakefield in this way would enable the use of different technologies, such as fibre or thin-disc lasers, which are able to operate at multi-kilohertz pulse repetition rates and with wall-plug efficiencies two orders of magnitude higher than current laser systems. We outline the parameters of efficient, GeV-scale, 10-kHz plasma accelerators and show that they could drive compact X-ray sources with average photon fluxes comparable to those of third-generation light source but wi...

  1. Mortality rate acceleration and post-reproductive lifespan in matrilineal whale species.

    Foote, Andrew D

    2008-04-23

    The strength of selection to increase the span of a life stage is dependent upon individuals at that stage being able to contribute towards individual fitness and the probability of their surviving to that stage. Complete reproductive cessation and a long post-reproductive female lifespan as found in humans are also found in killer whale (Orcinus orca) and short-finned pilot whale (Globicephala macrorhynchus), but not in the long-finned pilot whale (Globicephala melaena). Each species forms kin-based, stable matrilineal groups and exhibits kin-directed behaviours that could increase inclusive fitness. Here, the initial mortality rate and mortality rate-doubling time of females of these three closely related whale species are compared. The initial mortality rate shows little variation among pilot whale species; however mortality rate accelerates almost twice as fast in the long-finned pilot whale as it does in killer whale and short-finned pilot whale. Selection for a long post-reproductive female lifespan in matrilineal whales may therefore be determined by the proportion of females surviving past the point of reproductive cessation. PMID:18252662

  2. Canine fetal heart rate: do accelerations or decelerations predict the parturition day in bitches?

    Gil, E M U; Garcia, D A A; Giannico, A T; Froes, T R

    2014-10-15

    Ultrasonography is a safe and efficient technique for monitoring fetal development and viability. One of the most important and widely used parameters to verify fetal viability is the fetal heart rate (HR). In human medicine, the fetal HR normally oscillates during labor in transient accelerations and decelerations associated with uterine contractions. The present study investigated whether these variations also occur in canine fetuses and its relationship to parturition. A cohort study was conducted in 15 pregnant bitches undergoing two-dimensional high-resolution ultrasonographic examination during the 8th and 9th week of gestation. Fetal HR was assessed in M-mode for 5 minutes in each fetus in all bitches. In addition, the bitches were monitored for clinical signs of imminent parturition. Associations between the HR, antepartum time, and delivery characteristics were evaluated with a Poisson regression model. Fetal HR acceleration and deceleration occurred in canine fetuses and predicted the optimal time of parturition. These findings can help veterinarians and sonographers better understand this phenomenon in canine fetuses. PMID:24888684

  3. The complete plastid genome sequence of Welwitschia mirabilis: an unusually compact plastome with accelerated divergence rates

    Boore Jeffrey L

    2008-05-01

    Full Text Available Abstract Background Welwitschia mirabilis is the only extant member of the family Welwitschiaceae, one of three lineages of gnetophytes, an enigmatic group of gymnosperms variously allied with flowering plants or conifers. Limited sequence data and rapid divergence rates have precluded consensus on the evolutionary placement of gnetophytes based on molecular characters. Here we report on the first complete gnetophyte chloroplast genome sequence, from Welwitschia mirabilis, as well as analyses on divergence rates of protein-coding genes, comparisons of gene content and order, and phylogenetic implications. Results The chloroplast genome of Welwitschia mirabilis [GenBank: EU342371] is comprised of 119,726 base pairs and exhibits large and small single copy regions and two copies of the large inverted repeat (IR. Only 101 unique gene species are encoded. The Welwitschia plastome is the most compact photosynthetic land plant plastome sequenced to date; 66% of the sequence codes for product. The genome also exhibits a slightly expanded IR, a minimum of 9 inversions that modify gene order, and 19 genes that are lost or present as pseudogenes. Phylogenetic analyses, including one representative of each extant seed plant lineage and based on 57 concatenated protein-coding sequences, place Welwitschia at the base of all seed plants (distance, maximum parsimony or as the sister to Pinus (the only conifer representative in a monophyletic gymnosperm clade (maximum likelihood, bayesian. Relative rate tests on these gene sequences show the Welwitschia sequences to be evolving at faster rates than other seed plants. For these genes individually, a comparison of average pairwise distances indicates that relative divergence in Welwitschia ranges from amounts about equal to other seed plants to amounts almost three times greater than the average for non-gnetophyte seed plants. Conclusion Although the basic organization of the Welwitschia plastome is typical, its

  4. The effects of accelerated growth rates and estrogen implants in prepubertal Holstein heifers on growth, feed efficiency, and blood parameters.

    Lammers, B P; Heinrichs, A J; Kensinger, R S

    1999-08-01

    Sixty-eight Holstein heifers were used to determine the effects of accelerated growth rates by increased nutrient intake and estrogen implants on feed efficiency, structural growth, and blood parameters in heifers between 19 and 39 wk of age. At the beginning of the treatment period, the heifers were assigned to one of four treatment groups by using a randomized complete block design in a 2 x 2 factorial arrangement. The treatments were standard growth rate (700 g/d), accelerated growth rate (1000 g/d), standard growth rate with an estradiol implant, and accelerated growth rate with an estradiol implant. All heifers received the same diet, but dry matter intake was adjusted weekly to achieve the target rate of gain. Accelerating heifer growth rates from 705 to 1007 g/d improved feed efficiency 5.1%, increased the rate of withers height, heart girth, and hip width growth 12, 27, and 27%, respectively, and body condition scores 0.25 points. Estradiol implants improved feed efficiency 2.4% and decreased the rate of withers height 6% and heart girth growth 3.5%. Increased nutrient intake and average daily gain depressed mean plasma growth hormone and urea nitrogen content 17 and 7%, respectively, while elevating insulin-like growth factor-1 levels by 10%. Estradiol implants increased mean plasma growth hormone content by 29% and insulin-like growth factor-1 levels by 17%, but decreased urea nitrogen content by 11%. Feeding prepubertal heifers for accelerated growth rates increased structural growth with a small increase in body condition, whereas estradiol implants improved feed efficiency and decreased the growth rate of withers height and heart girth without affecting the rate of hip width growth. PMID:10480101

  5. Safety confirmation study of TRUEX solvent by accelerating rate calorimeter (ARC)

    In order to confirm the engineering safety on the TRUEX solvent (mixed solvent of CMPO/TBP/n-dodecane) for separating the transuranics from high-level activity liquid waste in advanced nuclear fuel recycling technological R and D, thermal behavior and pressure behavior in heating PUREX solvent (mixed solvent of 30% TBP-n-dodecane), TRUEX solvent and in the exothermic reaction of TRUEX solvent etc. and nitric acid in sealed adiabatic system which was severer condition than actual plant were measured by using accelerating rate calorimeter (ARC). The Arrhenius parameters (activation energy and frequency factor) which are necessary for the evaluation of reaction rate was examined from the measurement data in ARC. Analytical method and analysis condition of reaction products were examined in order to clarify chemical form of reaction products in exothermic reaction between solvent and nitric acid in ARC, and the qualitative evaluation was carried out. Main results are shown in the following. 1) TBP, CMPO, n-dodecane and 10 M nitric acid hardly exothermed in the simple substance. 2) On the solvent phase after the solvent contacted with 10 M nitric acid and the equilibrium has been attained (single-phase sample), the heat quantity per unit sample weight of the TRUEX solvent tended to be bigger than that of the PUREX solvent when heat quantity was evaluated in ARC. However, on the mixed sample of solvent and 10 M nitric acid enclosed in a sample container simultaneously (two phase system sample), the heat quantity per unit solvent weight was almost equivalent for PUREX solvent and TRUEX solvent. 3) The kinetic analysis was carried out, and on the TBP-10 M nitric acid single-phase sample, the activation energy of the reaction was evaluated to be 118 kJ/mol. Its activation energy was approximately equal to 112 kJ/mol by Nichols. The reaction rate constant was calculated, and it was shown that reaction rate constants of PUREX solvent-10 M nitric acid single-phase sample and

  6. A population-based experimental model for protein evolution: Effects of mutation rate and selection stringency on evolutionary outcomes

    Leconte, Aaron M; Dickinson, Bryan; Yang, David D.; Chen, Irene; Allen, Benjamin; Liu, David Ruchien

    2013-01-01

    Protein evolution is a critical component of organismal evolution and a valuable method for the generation of useful molecules in the laboratory. Few studies, however, have experimentally characterized how fundamental parameters influence protein evolution outcomes over long evolutionary trajectories or multiple replicates. In this work, we applied phage-assisted continuous evolution (PACE) as an experimental platform to study evolving protein populations over hundreds of rounds of evolution....

  7. Shifting gears: Thermodynamics of genetic information storage suggest stress-dependence of mutation rate, which can accelerate adaptation

    Hilbert, Lennart

    2011-01-01

    Background: Acceleration of adaptation dynamics by stress-induced hypermutation has been found experimentally. Evolved evolvability is a prominent explanation. We investigate a more generally applicable explanation by a physical constraint. Methods and Results: A generic thermodynamical analysis of genetic information storage obviates physical constraints on the integrity of genetic information. The capability to employ metabolic resources is found as a major determinant of mutation probability in stored genetic information. Incorporation into a non-recombinant, asexual adaptation toy model predicts cases of markedly accelerated adaptation, driven by a transient increase of mutation rate. No change in the mutation rate as a genetic trait is required. The mutation rate of one and the same genotype varies dependent on stress level. Implications: Stress-dependent mutation rates are physically necessary and challenge a condition-independent genotype to mutation rate mapping. This holds implications for evolutiona...

  8. Thermal runaway features of large format prismatic lithium ion battery using extended volume accelerating rate calorimetry

    Feng, Xuning; Fang, Mou; He, Xiangming; Ouyang, Minggao; Lu, Languang; Wang, Hao; Zhang, Mingxuan

    2014-06-01

    In this paper, the thermal runaway features of a 25 Ah large format prismatic lithium ion battery with Li(NixCoyMnz)O2 (NCM) cathode are evaluated using the extended volume-accelerating rate calorimetry (EV-ARC). 4 thermocouples are set at different positions of the battery. The temperature inside the battery is 870 °C or so, much higher than that outside the battery. The temperature difference is calculated from the recorded data. The temperature difference within the battery stays lower than 1 °C for 97% of the test period, while it rises to its highest, approximately 520 °C, when thermal runaway happens. The voltage of the battery is also measured during the test. It takes 15-40 s from the sharp drop of voltage to the instantaneous rise of temperature. Such a time interval is beneficial for early warning of the thermal runaway. Using a pulse charge/discharge profile, the internal resistance is derived from the quotient of the pulse voltage and the current during the ARC test. The internal resistance of the battery increases slowly from 20 mΩ to 60 mΩ before thermal runaway, while it rises to 370 mΩ when thermal runaway happens indicating the loss of the integrity of the separator or the battery swell.

  9. Validation of a new control system for Elekta accelerators facilitating continuously variable dose rate

    Bertelsen, Anders; Lorenzen, Ebbe L; Brink, Carsten

    2011-01-01

    ) as well as BVDR. Using CVDR opposed to BVDR for VMAT has the potential of reducing the treatment time but may lead to lower dosimetric accuracy due to faster moving accelerator parts. Using D7 and a test version of Integrity, differences in ability to control the accelerator, treatment efficiency...

  10. The performance of Botswana's traditional arable agriculture: growth rates and the impact of the accelerated rainfed arable programme (ARAP)

    Seleka, Tebogo B.

    1999-01-01

    This study assesses the performance of Botswana's traditional arable agriculture for the 1968-90 period. Growth rate and arable sub-sector production models are specified and estimated to determine how the sub-sector performed over time, and to capture the impact of the Accelerated Rainfed Arable Programme (ARAP). Growth rate model results indicate that cultivated area increased by about 2.2% per year during the 1968-90 period. However, crop output remained unchanged and yields declined by ab...

  11. Current evolutionary adaptiveness of psychiatric disorders: Fertility rates, parent-child relationship quality, and psychiatric disorders across the lifespan.

    Jacobson, Nicholas C

    2016-08-01

    This study sought to evaluate the current evolutionary adaptiveness of psychopathology by examining whether these disorders impact the quantity of offspring or the quality of the parent-child relationship across the life span. Using the National Comorbidity Survey, this study examined whether DSM-III-R anxiety, posttraumatic stress, depressive, bipolar, substance use, antisocial, and psychosis disorders predicted later fertility and the quality of parent-child relationships across the life span in a national sample (N = 8,098). Using latent variable and varying coefficient models, the results suggested that anxiety in males and bipolar pathology in males and females were associated with increased fertility at younger ages. The results suggested almost all other psychopathology was associated with decreased fertility in middle to late adulthood. The results further suggested that all types of psychopathology had negative impacts on the parent-child relationship quality (except for antisocial pathology in males). Nevertheless, for all disorders, the impact of psychopathology on both fertility and the parent-child relationship quality was affected by the age of the participant. The results also showed that anxiety pathology is associated with a high-quantity, low-quality parenting strategy followed by a low-quantity, low-quality parenting strategy. Further, the results suggest that bipolar pathology is associated with an early high-quantity and a continued low-quality parenting strategy. Posttraumatic stress, depression, substance use, antisocial personality, and psychosis pathology are each associated with a low-quantity, low-quality parenting strategy, particularly in mid to late adulthood. These findings suggest that the evolutionary impact of psychopathology depends on the developmental context. (PsycINFO Database Record PMID:27362490

  12. A novel dimeric thymosin beta 4 with enhanced activities accelerates the rate of wound healing

    Xu TJ

    2013-10-01

    Full Text Available Tian-Jiao Xu,1,2,* Qi Wang,1,* Xiao-Wen Ma,1 Zhen Zhang,3 Wei Zhang,1 Xiao-Chang Xue,1 Cun Zhang,1 Qiang Hao,1 Wei-Na Li,1 Ying-Qi Zhang,1 Meng Li11State Key Laboratory of Cancer Biology, Biotechnology Center, School of Pharmacy, Fourth Military Medical University, Xi’an, People’s Republic of China; 2The Institute of Medicine, Qiqihar Medical University, Qiqihar, People’s Republic of China; 3Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA*These authors contributed equally to this workObjective: Thymosin beta 4 (Tβ4 is a peptide with 43 amino acids that is critical for repair and remodeling tissues on the skin, eye, heart, and neural system following injury. To fully realize its utility as a treatment for disease caused by injury, the authors constructed a cost-effective novel Tβ4 dimer and demonstrated that it was better able to accelerate tissue repair than native Tβ4.Methods: A prokaryotic vector harboring two complete Tβ4 genes with a short linker was constructed and expressed in Escherichia coli. A pilot-scale fermentation (10 L was performed to produce engineered bacteria and the Tβ4 dimer was purified by one-step hydrophobic interaction chromatography. The activities of the Tβ4 dimer to promote endothelial cell proliferation, migration, and sprouting were assessed by tetramethylbenzidine (methylthiazol tetrazolium, trans-well, scratch, and tube formation assays. The ability to accelerate dermal healing was assessed on rats.Results: After fermentation, the Tβ4 dimer accounted for about 30% of all the bacteria proteins. The purity of the Tβ4 dimer reached 98% after hydrophobic interaction chromatography purification. An average of 562.4 mg/L Tβ4 dimer was acquired using a 10 L fermenter. In each assay, the dimeric Tβ4 exhibited enhanced activities compared with native Tβ4. Notably, the ability of the dimeric Tβ4 to promote cell migration was almost two times higher

  13. Evolutionary Expectations

    Nash, Ulrik William

    2014-01-01

    The concept of evolutionary expectations descends from cue learning psychology, synthesizing ideas on rational expectations with ideas on bounded rationality, to provide support for these ideas simultaneously. Evolutionary expectations are rational, but within cognitive bounds. Moreover, they are...... cognitive bounds will perceive business opportunities identically. In addition, because cues provide information about latent causal structures of the environment, changes in causality must be accompanied by changes in cognitive representations if adaptation is to be maintained. The concept of evolutionary...

  14. Evolutionary Computing

    Eiben, Aguston; Schoenauer, Marc

    2002-01-01

    Evolutionary computing (EC) is an exciting development in Computer Science. It amounts to building, applying and studying algorithms based on the Darwinian principles of natural selection. In this paper we briefly introduce the main concepts behind evolutionary computing. We present the main components all evolutionary algorithms (EA), sketch the differences between different types of EAs and survey application areas ranging from optimization, modeling and simulation to entertainment.

  15. Experimental Study of the Effect of Beam Loading on RF Breakdown Rate in CLIC High-Gradient Accelerating Structures

    Tecker, F; Kelisani, M; Doebert, S; Grudiev, A; Quirante, J; Riddone, G; Syratchev, I; Wuensch, W; Kononenko, O; Solodko, A; Lebet, S

    2013-01-01

    RF breakdown is a key issue for the multi-TeV highluminosity e+e- Compact Linear Collider (CLIC). Breakdowns in the high-gradient accelerator structures can deflect the beam and decrease the desired luminosity. The limitations of the accelerating structures due to breakdowns have been studied so far without a beam present in the structure. The presence of the beam modifies the distribution of the electrical and magnetic field distributions, which determine the breakdown rate. Therefore an experiment has been designed for high power testing a CLIC prototype accelerating structure with a beam present in the CLIC Test Facility (CTF3). A special beam line allows extracting a beam with nominal CLIC beam current and duration from the CTF3 linac. The paper describes the beam optics design for this experimental beam line and the commissioning of the experiment with beam.

  16. Setting accelerated dissolution test for PLGA microspheres containing peptide, investigation of critical parameters affecting drug release rate and mechanism.

    Tomic, I; Vidis-Millward, A; Mueller-Zsigmondy, M; Cardot, J-M

    2016-05-30

    The objective of this study was development of accelerated in vitro release method for peptide loaded PLGA microspheres using flow-through apparatus and assessment of the effect of dissolution parameters (pH, temperature, medium composition) on drug release rate and mechanism. Accelerated release conditions were set as pH 2 and 45°C, in phosphate buffer saline (PBS) 0.02M. When the pH was changed from 2 to 4, diffusion controlled phases (burst and lag) were not affected, while release rate during erosion phase decreased two-fold due to slower ester bonds hydrolyses. Decreasing temperature from 45°C to 40°C, release rate showed three-fold deceleration without significant change in release mechanism. Effect of medium composition on drug release was tested in PBS 0.01M (200 mOsm/kg) and PBS 0.01M with glucose (380 mOsm/kg). Buffer concentration significantly affected drug release rate and mechanism due to the change in osmotic pressure, while ionic strength did not have any effect on peptide release. Furthermore, dialysis sac and sample-and-separate techniques were used, in order to evaluate significance of dissolution technique choice on the release process. After fitting obtained data to different mathematical models, flow-through method was confirmed as the most appropriate for accelerated in vitro dissolution testing for a given formulation. PMID:27025293

  17. Development of high power toroidal pulse transformer with 10-100 Hz repetition rate for linear induction accelerator

    Full text: An amorphous-core pulse transformer of 2.5kV /20kV, 20μs, 250J, 100 pps rating has been designed and fabricated for Linear Induction Accelerator. This accelerator will be used to generate intense electron beam pulses at high repetition rate for plastic modification and other material processing applications. The peak power and average power of the pulse transformer are 20MW and 25kW respectively. Modular design based on parallel operation of 6 identical modules has been incorporated in this pulse transformer. Single module has been tested up to 10pps for 10 minute durations. Full transformer assembly has been tested in single pulse mode

  18. Concept for calculating dose rates from activated groundwater at accelerator sites

    Prolingheuer, N; Vanderborght, J; Schlögl, B; Nabbi, R; Moormann, R

    Licensing of particle accelerators requires the proof that the groundwater outside of the site will not be significantly contaminated by activation products formed below accelerator and target. In order to reduce the effort for this proof, a site independent simplified but conservative method is under development. The conventional approach for calculation of activation of soil and groundwater is shortly described on example of a site close to Forschungszentrum Juelich, Germany. Additionally an updated overview of a data library for partition coefficients for relevant nuclides transported in the aquifer at the site is presented. The approximate model for transport of nuclides with ground water including exemplary results on nuclide concentrations outside of the site boundary and of resulting effective doses is described. Further applications and developments are finally outlined.

  19. Rating forces grip and driving and accelerations of the car with drive different configuration

    Kowalski Mariusz

    2015-12-01

    Full Text Available The paper shows a typical drive systems used in today's vehicles, mainly cars. Approximated scheme of the formation of the driving force of the vehicle and the necessary mathematical relations for the calculation. For example, a typical passenger car BMW 320 was analyzed and calculations obtained a driving force, of adhesion and acceleration. The calculations were performed for the drive system, the classical (i.e. the rear axle of the vehicle for front-wheel drive and four-wheel drive (4×4. Virtually assumed that to the above mentioned vehicle it is possible buildings of each of said system. These are shown graphically in diagrams bearing a distribution of the forces acting on the substrate and the reactions - the data necessary for the calculations. The resulting calculation is graphically shown in the diagrams, in which is illustrated a change value of the resulting adhesive strength, and the acceleration depending on the drive type vehicle.

  20. Transient accelerations of fetal heart rate analyzed by computerized cardiotocography in the third trimester of pregnancy

    Ana Luisa Fernandes Lauletta

    2014-06-01

    Full Text Available Objective: the aim of this study was to investigate the patterns of transient FHR accelerations (10 bpm and 15 bpm in the third trimester of pregnancy, comparing the occurrence of this event before and after the 32nd gestational week. Methods: This is a prospective study comparing the results of the computerized cardiotocography of 46 low-risk women with singleton pregnancies, maternal age between 18 and 40 years, gestational age between 28 and 40 weeks, absence of maternal morbidity and adequate fetal growth according to ultrasound. Computed Cardiotocography (8002 Sonicaid System and Fetal Care System was performed for 30 minutes to analyze the variables of FHR. Results: twenty-three pregnant women underwent cardiotocography before 32 weeks (mean = 29.9 weeks, SD = 1.4 weeks and were compared with 23 pregnant women who were examined after 32 weeks (mean = 36.3 weeks, SD = 2.5 weeks. Regarding the characteristics of FHR, fetuses evaluated between 32 1/7 weeks and 40 weeks showed a significantly greater number of accelerations above 15 bpm (median = 5, variation 0-18 than the group of pregnant women from 28 to 32 weeks (median = 4, variation 0 to 10; P = 0.048. There was a significant positive correlation between the number of accelerations above 15 bpm and the gestational age at examination (rho = 0.33; P = 0.026. Conclusion: computerized cardiotocography showed an association regarding the number of transient accelerations greater than 15 bpm in the assessment of both periods before and after 32 weeks of gestational age, suggesting the influence of the maturation of the fetal autonomic nervous system with pregnancy progression.

  1. Transient accelerations of fetal heart rate analyzed by computerized cardiotocography in the third trimester of pregnancy

    Ana Luisa Fernandes Lauletta; Roseli Mieko Yamamoto Nomura; Seizo Miyadahira; Rossana Pulcineli Vieira Francisco; Marcelo Zugaib

    2014-01-01

    Objective: the aim of this study was to investigate the patterns of transient FHR accelerations (10 bpm and 15 bpm) in the third trimester of pregnancy, comparing the occurrence of this event before and after the 32nd gestational week. Methods: This is a prospective study comparing the results of the computerized cardiotocography of 46 low-risk women with singleton pregnancies, maternal age between 18 and 40 years, gestational age between 28 and 40 weeks, absence of maternal morbidity and a...

  2. Optimized ion acceleration using high repetition rate, variable thickness liquid crystal targets

    Poole, Patrick; Willis, Christopher; Cochran, Ginevra; Andereck, C. David; Schumacher, Douglass

    2015-11-01

    Laser-based ion acceleration is a widely studied plasma physics topic for its applications to secondary radiation sources, advanced imaging, and cancer therapy. Recent work has centered on investigating new acceleration mechanisms that promise improved ion energy and spectrum. While the physics of these mechanisms is not yet fully understood, it has been observed to dominate for certain ranges of target thickness, where the optimum thickness depends on laser conditions including energy, pulse width, and contrast. The study of these phenomena is uniquely facilitated by the use of variable-thickness liquid crystal films, first introduced in P. L. Poole et al. PoP21, 063109 (2014). Control of the formation parameters of these freely suspended films such as volume, temperature, and draw speed allows on-demand thickness variability between 10 nanometers and several 10s of microns, fully encompassing the currently studied thickness regimes with a single target material. The low vapor pressure of liquid crystal enables in-situ film formation and unlimited vacuum use of these targets. Details on the selection and optimization of ion acceleration mechanism with target thickness will be presented, including recent experiments on the Scarlet laser facility and others. This work was performed with support from the DARPA PULSE program through a grant from AMRDEC and by the NNSA under contract DE-NA0001976.

  3. The Chemically Homogeneous Evolutionary Channel for Binary Black Hole Mergers: Rates and Properties of Gravitational-Wave Events Detectable by Advanced Ligo

    de Mink, S E

    2016-01-01

    We explore the predictions for detectable gravitational-wave signals from merging binary black holes formed through chemically homogeneous evolution in massive short-period stellar binaries. We find that ~500 events per year could be detected with advanced ground-based detectors operating at full sensitivity. We analyze the distribution of detectable events, and conclude that there is a very strong preference for detecting events with nearly equal components (mass ratio >0.66 at 90% confidence in our default model) and high masses (total source-frame mass between 57 and $103\\, M_\\odot$ at 90% confidence). We consider multiple alternative variations to analyze the sensitivity to uncertainties in the evolutionary physics and cosmological parameters, and conclude that while the rates are sensitive to assumed variations, the mass distributions are robust predictions. Finally, we consider the recently reported results of the analysis of the first 16 double-coincident days of the O1 LIGO observing run, and find tha...

  4. Evolutionary Economics

    Dopfer, Kurt

    2006-01-01

    The paper provides an overview of major recent contributions in evolutionary economics. It starts of demonstrating that the pioneers of this approach such as Veblen, Schumpeter, Marshall and Hayek saw the economy as continuously changing and that this kind of "realism of perception" guides essentially also contemporary evolutionary economics. The economy is viewed as an evolving system of structured knowledge governing economic operations. Theoretically, a micro-meso-macro architecture is pro...

  5. Evolutionary algorithms

    Szöllösi, Tomáš

    2012-01-01

    The first part of this work deals with the optimization and evolutionary algorithms which are used as a tool to solve complex optimization problems. The discussed algorithms are Differential Evolution, Genetic Algorithm, Simulated Annealing and deterministic non-evolutionary algorithm Taboo Search.. Consequently the discussion is held on the issue of testing the optimization algorithms through the use of the test function gallery and comparison solution all algorithms on Travelling salesman p...

  6. Evolutionary algorithms

    Eremeev, Anton V.

    2015-01-01

    This manuscript contains an outline of lectures course "Evolutionary Algorithms" read by the author in Omsk State University n.a. F.M.Dostoevsky. The course covers Canonic Genetic Algorithm and various other genetic algorithms as well as evolutioanry algorithms in general. Some facts, such as the Rotation Property of crossover, the Schemata Theorem, GA performance as a local search and "almost surely" convergence of evolutionary algorithms are given with complete proofs. The text is in Russian.

  7. Benefit of chromium in reducing the rates of flow accelerated corrosion of carbon steel outlet feeders in CANDU reactors

    In the mid 1990's, wall thinning of outlet feeders due to flow accelerated corrosion (FAC) was recognized as an active mechanism in the outlet feeders of CANDU reactors. To address wall thinning of outlet feeders in new reactor construction and refurbishment projects, AECL introduced a minimum Cr concentration in its specification for the SA-106 carbon steel feeder pipe. The effectiveness of Cr in reducing FAC was subsequently demonstrated in in-reactor and out-reactor loops at AECL's Chalk River Laboratories. More recently, wall-thinning rates have been determined from wall thickness data collected from outlet feeders, containing a specified minimum Cr concentration, installed in the Point Lepreau Generating Station in 2001. This paper presents the FAC rates determined from in-service outlet feeders and compares the rates with data from previous in-reactor and out-reactor test loops, highlighting the consistency observed in results from the three sources. (author)

  8. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    He, Z.-H; Thomas, A. G. R.; Beaurepaire, B; Nees, J. A.; Hou, B.; Malka, Victor; Krushelnick, K; Faure, Jérôme

    2013-01-01

    We show that electron bunches in the 50-100 keV range can be produced from a laser wake-field accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source and the fact that its uncorrelated bu...

  9. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    He, Z.-H.; Thomas, A. G. R.; Beaurepaire, B.; Nees, J. A.; Hou, B.; Malka, V.; Krushelnick, K.; Faure, J.

    2013-02-01

    We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

  10. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    We show that electron bunches in the 50–100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

  11. An Evolutionary Model for Collapsing Molecular Clouds and Their Star Formation Activity. II. Mass Dependence of the Star Formation Rate

    Zamora-Avilés, Manuel

    2013-01-01

    In a previous study, we presented a semi-analytical model for the regulation of the star formation rate (SFR) and efficiency (SFE) in which the molecular clouds (MCs) were assumed to be in gravitational collapse, and the SFR was instantaneously controlled by evaporation of the cloud material by massive-star ionization feedback. In this model, the main parameter controlling the evolution of the clouds was found to be the gas mass involved in the process and here we discuss various properties of the SFR and SFE as a function of the cloud masses, that can be compared with observations and implemented in numerical models of galactic evolution. Because the model neglects magnetic fields, supernova explosions, and radiation pressure, the results presented are upper limits. We find that $\\SFRavg$ and $\\SFEavg$ are well represented as functions of the maximum cloud mass by the fits $\\SFRavg \\approx 100 (1+\\Mmax/2 \\times 10^5 ~ \\Msun)^{2} ~ \\Msun \\Myr^{-1}$ and $\\SFEavg \\approx 0.024 (\\Mmax/10^5 ~ \\Msun)^{0.28}$, resp...

  12. A hybrid evolutionary algorithm for multi-objective anatomy-based dose optimization in high-dose-rate brachytherapy

    Multiple objectives must be considered in anatomy-based dose optimization for high-dose-rate brachytherapy and a large number of parameters must be optimized to satisfy often competing objectives. For objectives expressed solely in terms of dose variances, deterministic gradient-based algorithms can be applied and a weighted sum approach is able to produce a representative set of non-dominated solutions. As the number of objectives increases, or non-convex objectives are used, local minima can be present and deterministic or stochastic algorithms such as simulated annealing either cannot be used or are not efficient. In this case we employ a modified hybrid version of the multi-objective optimization algorithm NSGA-II. This, in combination with the deterministic optimization algorithm, produces a representative sample of the Pareto set. This algorithm can be used with any kind of objectives, including non-convex, and does not require artificial importance factors. A representation of the trade-off surface can be obtained with more than 1000 non-dominated solutions in 2-5 min. An analysis of the solutions provides information on the possibilities available using these objectives. Simple decision making tools allow the selection of a solution that provides a best fit for the clinical goals. We show an example with a prostate implant and compare results obtained by variance and dose-volume histogram (DVH) based objectives

  13. An evolutionary model for collapsing molecular clouds and their star formation activity. II. Mass dependence of the star formation rate

    We discuss the evolution and dependence on cloud mass of the star formation rate (SFR) and efficiency (SFE) of star-forming molecular clouds (MCs) within the scenario that clouds are undergoing global collapse and that the SFR is controlled by ionization feedback. We find that low-mass clouds (M max ≲ 104 M ☉) spend most of their evolution at low SFRs, but end their lives with a mini-burst, reaching a peak SFR ∼104 M ☉ Myr–1, although their time-averaged SFR is only (SFR) ∼ 102 M ☉ Myr–1. The corresponding efficiencies are SFEfinal ≲ 60% and (SFE) ≲ 1%. For more massive clouds (M max ≳ 105 M ☉), the SFR first increases and then reaches a plateau because the clouds are influenced by stellar feedback since earlier in their evolution. As a function of cloud mass, (SFR) and (SFE) are well represented by the fits (SFR) ≈ 100(1 + M max/1.4 × 105 M ☉)1.68 M ☉ Myr–1 and (SFE) ≈ 0.03(M max/2.5 × 105 M ☉)0.33, respectively. Moreover, the SFR of our model clouds follows closely the SFR-dense gas mass relation recently found by Lada et al. during the epoch when their instantaneous SFEs are comparable to those of the clouds considered by those authors. Collectively, a Monte Carlo integration of the model-predicted SFR(M) over a Galactic giant molecular cloud mass spectrum yields values for the total Galactic SFR that are within half an order of magnitude of the relation obtained by Gao and Solomon. Our results support the scenario that star-forming MCs may be in global gravitational collapse and that the low observed values of the SFR and SFE are a result of the interruption of each SF episode, caused primarily by the ionizing feedback from massive stars.

  14. Evolutionary awareness.

    Gorelik, Gregory; Shackelford, Todd K

    2014-01-01

    In this article, we advance the concept of "evolutionary awareness," a metacognitive framework that examines human thought and emotion from a naturalistic, evolutionary perspective. We begin by discussing the evolution and current functioning of the moral foundations on which our framework rests. Next, we discuss the possible applications of such an evolutionarily-informed ethical framework to several domains of human behavior, namely: sexual maturation, mate attraction, intrasexual competition, culture, and the separation between various academic disciplines. Finally, we discuss ways in which an evolutionary awareness can inform our cross-generational activities-which we refer to as "intergenerational extended phenotypes"-by helping us to construct a better future for ourselves, for other sentient beings, and for our environment. PMID:25300054

  15. Evolutionary macroecology

    José Alexandre F. Diniz-Filho

    2013-10-01

    Full Text Available Macroecology focuses on ecological questions at broad spatial and temporal scales, providing a statistical description of patterns in species abundance, distribution and diversity. More recently, historical components of these patterns have begun to be investigated more deeply. We tentatively refer to the practice of explicitly taking species history into account, both analytically and conceptually, as ‘evolutionary macroecology’. We discuss how the evolutionary dimension can be incorporated into macroecology through two orthogonal and complementary data types: fossils and phylogenies. Research traditions dealing with these data have developed more‐or‐less independently over the last 20–30 years, but merging them will help elucidate the historical components of diversity gradients and the evolutionary dynamics of species’ traits. Here we highlight conceptual and methodological advances in merging these two research traditions and review the viewpoints and toolboxes that can, in combination, help address patterns and unveil processes at temporal and spatial macro‐scales.

  16. Development of prediction method of flow accelerated corrosion (1). Evaluation of hydraulic factors and its correlation with thinning rate

    Flow Accelerated Corrosion (FAC) requires considerable attention in plant piping management, for its potential of catastrophic pipe rupture of main piping systems. In view of fluid dynamics, the most essential factor to be considered is mass transfer at the inner surface of the pipe. In the previous report, the authors have proposed a new mass transfer coefficient model, which is adaptable to various types of piping elements with strong turbulence, by introducing the idea of 'Effective Friction Velocity' from the hydraulics in the viscous sub-layer along the wall. And in the present report, the model has been revised with rational logic, and verified with additional data obtained in FAC experiments with AVT water condition and CFD for the flow in the experiments. Furthermore, some discussion was made by considering the correlation of the thinning rate and the product of mass transfer and iron solubility, for the prospect of thinning rate prediction. (author)

  17. Cyclodextrin-based artificial oxidases with high rate accelerations and selectivity

    Zhou, You; Lindbäck, Emil Anders; Pedersen, Christian Marcus;

    2014-01-01

    Three cyclodextrin derivatives with one to four 2-O-formylmethyl groups attached to the secondary rim were prepared and investigated as catalysts for the oxidation of aminophenols in buffered dilute hydrogen peroxide. The derivatives were found to be Michaelis-Menten catalysts and to give rate ac...

  18. UVB Exposure Does Not Accelerate Rates of Litter Decomposition in a Semiarid Riparian Ecosystem

    Uselman, S. M.; Snyder, K. A.; Blank, R. R.; Jones, T. J.

    2010-12-01

    Aboveground litter decomposition is controlled mainly by substrate quality and climate factors across terrestrial ecosystems, but photodegradation from exposure to high-intensity ultraviolet-B (UVB) radiation may also be important in arid and semi-arid environments. We investigated the interactive effects of UVB exposure and litter quality on decomposition in a Tamarix-invaded riparian ecosystem during the establishment of an insect biological control agent in northern Nevada. Feeding by the northern tamarisk beetle (Diorhabda carinulata) on Tamarix spp. trees leads to altered leaf litter quality and increased exposure to solar UVB radiation from canopy opening. In addition, we examined the dynamics of litter decomposition of the invasive exotic Lepidium latifolium, because it is well-situated to invade beetle-infested Tamarix sites. Three leaf litter types (natural Tamarix, beetle-affected Tamarix, and L. latifolium) differing in substrate quality were decomposed in litterbags for one year in the field. Litterbags were subjected to one of three treatments: (1) Ambient UVB or (2) Reduced UVB (where UVB was manipulated by using clear plastic films that transmit or block UVB), and (3) No Cover (a control used to test for the effect of using the plastic films, i.e. a cover effect). Results showed a large cover effect on rates of decomposition and nutrient release, and our findings suggested that frequent cycles of freeze-thaw, and possibly rainfall intensity, influenced decomposition at this site. Contrary to our expectations, greater UVB exposure did not result in faster rates of decomposition. Greater UVB exposure resulted in decreased rates of decomposition and P release for the lower quality litter and no change in rates of decomposition and nutrient release for the two higher quality litter types, possibly due to a negative effect of UVB on soil microbes. Among litter types, rates of decomposition and net release of N and P followed this ranking: L. latifolium

  19. Isolation of Hox cluster genes from insects reveals an accelerated sequence evolution rate.

    Heike Hadrys

    Full Text Available Among gene families it is the Hox genes and among metazoan animals it is the insects (Hexapoda that have attracted particular attention for studying the evolution of development. Surprisingly though, no Hox genes have been isolated from 26 out of 35 insect orders yet, and the existing sequences derive mainly from only two orders (61% from Hymenoptera and 22% from Diptera. We have designed insect specific primers and isolated 37 new partial homeobox sequences of Hox cluster genes (lab, pb, Hox3, ftz, Antp, Scr, abd-a, Abd-B, Dfd, and Ubx from six insect orders, which are crucial to insect phylogenetics. These new gene sequences provide a first step towards comparative Hox gene studies in insects. Furthermore, comparative distance analyses of homeobox sequences reveal a correlation between gene divergence rate and species radiation success with insects showing the highest rate of homeobox sequence evolution.

  20. No accelerated rate of protein evolution in male-biased Drosophila pseudoobscura genes.

    Metta, Muralidhar; Gudavalli, Rambabu; Gibert, Jean-Michel; Schlotterer, Christian

    2006-01-01

    Sexually dimorphic traits are often subject to diversifying selection. Genes with a male-biased gene expression also are probably affected by sexual selection and have a high rate of protein evolution. We used SAGE to measure sex-biased gene expression in Drosophila pseudoobscura. Consistent with previous results from D. melanogaster, a larger number of genes were male biased (402 genes) than female biased (138 genes). About 34% of the genes changed the sex-related expression pattern between ...

  1. Particle Rate and Host Accelerator Beam Loss on the MICE Experiment

    Dobbs, Adam James [Imperial Coll., London; Imperial College, London (United Kingdom)

    2011-10-01

    A study is presented of particle rates in the MICE Muon Beamline and their relationship to beam loss produced in ISIS. A brief overview of neutrino physics is presented, together with a discussion on the Neutrino Factory as a motivation for MICE. An overview of MICE itself is then presented, highlighting the need for a systematic understanding of the relationship between the MICE target parameters, ISIS beam loss, and MICE particle rate. The variation of beam loss with target depth is examined and observed to be non-linear. The variation of beam loss with respect to the target dip time in the ISIS cycle is examined and observed to be approximately linear for dip times between 11.1 ms and 12.6 ms after ISIS injection, before tailing at earlier dip times. The variation of beam loss with particle rate is also observed to follow an approximately linear relationship from 0.05 V.ms to 4.7 V.ms beam loss, with a further strong indication that this continues up to 7.1 V.ms. Particle identification using time-of-flight data is used to give an insight into the relative abundances of each particle species present in the MICE beam. Estimates of muon rate are then produced as a function of beam loss. At a level of 2 V.ms beam loss ~10:9 muons per spill for a 3.2 ms spill with negative π → μ optics, and ~31:1 muons per 1 ms spill with positive π → μ optics are observed. Simulations using the ORBIT particle tracking code of the beam loss distributions around the ISIS ring, caused by the MICE target, are also presented and the implications for MICE running discussed.

  2. The limits of predictability of volcanic eruptions from accelerating rates of earthquakes

    Bell, A.F.; Naylor, M.; I. G. Main

    2013-01-01

    Volcanic eruptions are commonly preceded by increased rates of earthquakes. Previous studies argue that in some instances these sequences follow the inverse Omori law (IOL) and that this model could be the basis for forecasting the timing of eruption onset. However, the catalogue of pre-eruptive sequences is small, and the performance of the IOL as a forecasting tool remains largely untested. Here, we use simulations to quantify upper limits to the accuracy and bias of forecast eruption times...

  3. AN ACCELERATED RATE CALORIMETRY STUDY OF CAUSTIC-SIDE SOLVENT EXTRACTION SOLVENT WITHOUT EXTRACTANT

    This study found that 4 - 48 part per thousand (ppth) of Caustic Side Solvent Extraction (CSSX) solvent without extractant in caustic salt solution at evaporator-relevant temperatures result in no process-significant energetic events. However, the data suggest a chemical reaction (possible decomposition) in the CSSX solvent near 140 C. This concentration of entrained solvent is believed to markedly exceed the amount of solvent that will pass from the Modular Caustic Side Solvent Unit (MCU) through the downstream Defense Waste Processing Facility and enter the evaporator through routine tank farm operations. The rate of pressure rise at 140 C differs appreciably - i.e., is reduced - for salt solution containing the organic from that of the same solution without solvent. This behavior is due to a reaction between the CSSX components and the salt solution simulant

  4. Accelerating the averaging rate of atomic ensemble clock stability using atomic phase lock

    We experimentally demonstrated that the stability of an atomic clock improves at its fastest rate τ −1 (where τ is the averaging time) when the phase of a local oscillator is genuinely compared to the continuous phase of many atoms in a single trap (an atomic phase lock). For this demonstration, we developed a simple method that repeatedly monitors the atomic phase while retaining its coherence by observing only a portion of the whole ion cloud. Using this new method, we measured the continuous phase over three measurement cycles, and thereby improved the stability scaling from τ−1/2 to τ −1 during the three measurement cycles. This simple method provides a path by which atomic clocks can approach a quantum projection noise limit, even when the measurement noise is dominated by the technical noise. (paper)

  5. High rates of carbon storage in old deciduous forests: Emerging mechanisms from the Forest Accelerated Succession ExperimenT (FASET)

    Gough, C. M.; Nave, L. E.; Hardiman, B. S.; Bohrer, G.; Halperin, A.; Maurer, K.; Le Moine, J.; Nadelhoffer, K.; Vogel, C. S.; Curtis, P.; University Of Michigan Biological Station Forest Ecosystem Study (Umbs-Fest) Team

    2010-12-01

    Deciduous forests of the eastern US are broadly approaching an ecological threshold in which early successional dominant trees are senescing and giving way to later successional species, with unknown consequences for regional carbon (C) cycling. Though recent research demonstrates that forests may accumulate C for centuries, the mechanisms behind sustained rates of C storage in old, particularly deciduous, forests have not been identified. In a regionally representative forest at the University of Michigan Biological Station, we are combining observational and experimental C cycling studies to forecast how forest C storage responds to climate variation, disturbance, and succession. The Forest Accelerated Succession ExperimenT (FASET), in which >6,700 aspen and birch trees (~35 % LAI) were stem girdled within a 39 ha area, is testing the hypothesis that forest production will increase rather than decline with age, due to increases in nitrogen (N) availability, N allocation to the canopy, and the concurrent development of a more biologically and structurally complex canopy. Results thus far support our hypothesis that aging forests in the region may sustain high rates of C storage through shifts in N cycling and increased canopy complexity. Girdling-induced mortality of early successional species reduced soil respiration, accelerated fine root turnover, and prompted the redistribution of N from the foliage of early to later successional species. Nitrogen redistribution increased leaf area index (LAI) production by later successional species, offsetting declines in LAI from senescing early successional species. High rates of net primary production (NPP) were sustained in stands comprising a diverse assemblage of early and later successional species because later successional species, when already present in the canopy, rapidly compensated for declining growth of early successional species. Canopy structural complexity, which increased with forest age, was positively

  6. Evolutionary Psychology

    Heylighen, Francis

    2011-01-01

    Evolutionary psychology (EP) is an approach to the study of the mind that is founded on Darwin’s theory of evolution by natural selection. It assumes that our mental abilities, emotions and preferences are adapted specifically for solving problems of survival and reproduction in humanity’s ancestral environment, and derives testable predictions from this assumption. This has important implications for our understanding of the conditions for human well-being.

  7. Accelerated Growth Rate and Increased Drought Stress Resilience of the Model Grass Brachypodium distachyon Colonized by Bacillus subtilis B26.

    François Gagné-Bourque

    Full Text Available Plant growth-promoting bacteria (PGB induce positive effects in plants, for instance, increased growth and reduced abiotic stresses susceptibility. The mechanisms by which these bacteria impact the host plant are numerous, diverse and often specific. Here, we studied the agronomical, molecular and biochemical effects of the endophytic PGB Bacillus subtilis B26 on the full life cycle of Brachypodium distachyon Bd21, an established model species for functional genomics in cereal crops and temperate grasses. Inoculation of Brachypodium with B. subtilis strain B26 increased root and shoot weights, accelerated growth rate and seed yield as compared to control plants. B. subtilis strain B26 efficiently colonized the plant and was recovered from roots, stems and blades as well as seeds of Brachypodium, indicating that the bacterium is able to migrate, spread systemically inside the plant, establish itself in the aerial plant tissues and organs, and is vertically transmitted to seeds. The presence of B. subtilis strain B26 in the seed led to systemic colonization of the next generation of Brachypodium plants. Inoculated Brachypodium seedlings and mature plants exposed to acute and chronic drought stress minimized the phenotypic effect of drought compared to plants not harbouring the bacterium. Protection from the inhibitory effects of drought by the bacterium was linked to upregulation of the drought-response genes, DREB2B-like, DHN3-like and LEA-14-A-like and modulation of the DNA methylation genes, MET1B-like, CMT3-like and DRM2-like, that regulate the process. Additionally, total soluble sugars and starch contents increased in stressed inoculated plants, a biochemical indication of drought tolerance. In conclusion, we show a single inoculation of Brachypodium with a PGB affected the whole growth cycle of the plant, accelerating its growth rates, shortening its vegetative period, and alleviating drought stress effects. These effects are relevant to

  8. The degree of heart rate asymmetry is crucial for the validity of the deceleration and acceleration capacity indices of heart rate: A model-based study.

    Pan, Qing; Zhou, Gongzhan; Wang, Ruofan; Yu, Yihua; Li, Feng; Fang, Luping; Yan, Jing; Ning, Gangmin

    2016-09-01

    The deceleration capacity (DC) and acceleration capacity (AC) of heart rate are a pair of indices used for evaluating the autonomic nervous system (ANS). We assessed the role of heart rate asymmetry (HRA) in defining the relative performance of DC and AC using a mathematical model, which is able to generate a realistic RR interval (RRI) time series with controlled ANS states. The simulation produced a set of RRI series with random sympathetic and vagal activities. The multi-scale DCs and ACs were computed from the RRI series, and the correlation of DC and AC with the ANS functions was analyzed to evaluate the performance of the indices. In the model, the HRA level was modified by changing the inspiration/expiration (I/E) ratio to examine the influence of HRA on the performances of DC and AC. The results show that on the conventional scales (T=1, s=2), an HRA level above 50% results in a stronger association of DC with the ANS, compared with AC. On higher scales (T=4, s=6), there was no HRA and DC showed a similar performance to AC for all I/E ratios. The data suggest that the HRA level determines which of DC or AC is the optimal index for expressing ANS functions. Future clinical applications of DC and AC should be accompanied by an HRA analysis to provide a better index for assessing ANS. PMID:27392228

  9. Accelerated partial-breast irradiation using high-dose-rate interstitial brachytherapy: 12-year update of a prospective clinical study

    Background and purpose: To report the 12-year updated results of accelerated partial-breast irradiation (APBI) using multicatheter interstitial high-dose-rate (HDR) brachytherapy (BT). Patients and methods: Forty-five prospectively selected patients with T1N0-N1mi, nonlobular breast cancer without the presence of an extensive intraductal component and with negative surgical margins were treated with APBI after breast-conserving surgery (BCS) using interstitial HDR BT. A total dose of 30.3 Gy (n = 8) and 36.4 Gy (n = 37) in seven fractions within 4 days was delivered to the tumour bed plus a 1-2 cm margin. The median follow-up time was 133 months for surviving patients. Local and regional control, disease-free (DFS), cancer-specific (CSS), and overall survival (OS), as well as late side effects, and cosmetic results were assessed. Results: Four (8.9%) ipsilateral breast tumour recurrences were observed, for a 5-, 10-, and 12-year actuarial rate of 4.4%, 9.3%, and 9.3%, respectively. A total of two regional nodal failures were observed for a 12-year actuarial rate of 4.4%. The 12-year DFS, CSS, and OS was 75.3%, 91.1%, and 88.9%, respectively. Grade 3 fibrosis was observed in one patient (2.2%). No patient developed grade 3 teleangiectasia. Fat necrosis requiring surgical intervention occurred in one woman (2.2%). Cosmetic results were rated excellent or good in 35 patients (77.8%). Conclusions: Twelve-year results with APBI using HDR multicatheter interstitial implants continue to demonstrate excellent long-term local tumour control, survival, and cosmetic results with a low-rate of late side effects.

  10. Neutron equivalent dose rates at the surroundings of the electron linear accelerator operated by the university of Sao Paulo - Physics institute

    For the determination of the neutron dose rates at the surroundings of an electron linear accelerators it is necessary the knowledge of the neutron spectrum or its mean energy, because the conversion factor of the flux in equivalent dose rates, is strongly dependent on the neutron energy. Taking this fact into consideration, equivalent dose rates were determined in the three representative sites of the IF/USP Linear Electron Accelerator. Also, due to the radiation field be pulsed, a theoretical and experimental study has been realized to evaluate the effect produced by the variation of the field on the detector. (author)

  11. Dual-rate-loop control based on disturbance observer of angular acceleration for a three-axis aerial inertially stabilized platform.

    Zhou, Xiangyang; Jia, Yuan; Zhao, Qiang; Cai, Tongtong

    2016-07-01

    This paper presents a dual-rate-loop control method based on disturbance observer (DOB) of angular acceleration for a three-axis ISP for aerial remote sensing applications, by which the control accuracy and stabilization of ISP are improved obviously. In stabilization loop of ISP, a dual-rate-loop strategy is designed through constituting inner rate loop and the outer rate loop, by which the capability of disturbance rejection is advanced. Further, a DOB-based on angular acceleration is proposed to attenuate the influences of the main disturbances on stabilization accuracy. Particularly, an information fusion method is suggested to obtain accurate angular acceleration in DOB design, which is the key for the disturbance compensation. The proposed methods are theoretically analyzed and experimentally validated to illustrate the effectiveness. PMID:27016450

  12. Effect of predictive sign of acceleration on heart rate variability in passive translation situation: preliminary evidence using visual and vestibular stimuli in VR environment

    Watanabe Hiroshi

    2007-09-01

    Full Text Available Abstract Objective We studied the effects of the presentation of a visual sign that warned subjects of acceleration around the yaw and pitch axes in virtual reality (VR on their heart rate variability. Methods Synchronization of the immersive virtual reality equipment (CAVE and motion base system generated a driving scene and provided subjects with dynamic and wide-ranging depth information and vestibular input. The heart rate variability of 21 subjects was measured while the subjects observed a simulated driving scene for 16 minutes under three different conditions. Results When the predictive sign of the acceleration appeared 3500 ms before the acceleration, the index of the activity of the autonomic nervous system (low/high frequency ratio; LF/HF ratio of subjects did not change much, whereas when no sign appeared the LF/HF ratio increased over the observation time. When the predictive sign of the acceleration appeared 750 ms before the acceleration, no systematic change occurred. Conclusion The visual sign which informed subjects of the acceleration affected the activity of the autonomic nervous system when it appeared long enough before the acceleration. Also, our results showed the importance of the interval between the sign and the event and the relationship between the gradual representation of events and their quantity.

  13. An investigation of how radiation may cause accelerated rates of tropical cyclogenesis and diurnal cycles of convective activity

    Nicholls, M. E.

    2015-08-01

    Recent cloud-resolving numerical modeling results suggest that radiative forcing causes accelerated rates of tropical cyclogenesis and early intensification. Furthermore, observational studies of tropical cyclones have found that oscillations of the cloud canopy areal extent often occur that are clearly related to the solar diurnal cycle. A theory is put forward to explain these findings. The primary mechanism that seems responsible can be considered a refinement of the mechanism proposed by Gray and Jacobson (1977) to explain diurnal variations of oceanic tropical deep cumulus convection. It is hypothesized that differential radiative cooling or heating between a relatively cloud-free environment and a developing tropical disturbance generates circulations that can have very significant influences on convective activity in the core of the system. It is further suggested that there are benefits to understanding this mechanism by viewing it in terms of the lateral propagation of thermally driven gravity wave circulations, also known as buoyancy bores. Numerical model experiments indicate that mean environmental radiative cooling outside the cloud system is playing an important role in causing a significant horizontal differential radiative forcing and accelerating the rate of tropical cyclogenesis. As an expansive stratiform cloud layer forms aloft within a developing system the mean low-level radiative cooling is reduced, while at mid levels small warming occurs. During the daytime there is not a very large differential radiative forcing between the environment and the cloud system, but at nighttime when there is strong radiative clear-sky cooling of the environment it becomes significant. Thermally driven circulations develop, characterized by relatively weak subsidence in the environment but much stronger upward motion in the cloud system. This upward motion leads to a cooling tendency and increased relative humidity. The increased relative humidity at night

  14. Lower rates, better service, accelerated debt repayment: how best to sell a minority interest in Hydro One

    The sale of a minority stake in the provincially-owned, integrated electricity transmission and distribution company Hydro One is being contemplated by the Ontario government. Several options are open to the government to complete this sale, such as an income trust, an Initial Public Offering (IPO), straight sale of 49.9 per cent or less, and the separation and sale of the distribution operations. Some issues must be considered before proceeding with the divestiture: service quality and the current structure of the distribution sector in Ontario, the distribution and transmission rates, fostering competition in distribution, regulatory costs, tax leakage/stranded debt repayment, maximization of value to the province, public/stakeholder acceptance, foreign versus domestic ownership, accountability to consumers, and the policies/requirements of interconnected markets. The aim in the divestiture is to ensure customers in Ontario benefit from lower distribution rates, higher quality services, enhanced local accountability, a more efficient electricity industry, and accelerated stranded debt payoff. As a result, the Electricity Distributors Association is proposing that the government separate Hydro One's transmission and distribution. The rationale for the proposal was discussed in the paper, stressing the importance of making the decision now

  15. Evolutionary thinking

    Hunt, Tam

    2015-01-01

    Evolution as an idea has a lengthy history, even though the idea of evolution is generally associated with Darwin today. Rebecca Stott provides an engaging and thoughtful overview of this history of evolutionary thinking in her 2013 book, Darwin's Ghosts: The Secret History of Evolution. Since Darwin, the debate over evolution—both how it takes place and, in a long war of words with religiously-oriented thinkers, whether it takes place—has been sustained and heated. A growing share of this de...

  16. Two-Body Orbit Expansion Due to Time-Dependent Relative Acceleration Rate of the Cosmological Scale Factor

    Lorenzo Iorio

    2014-01-01

    Full Text Available By phenomenologically assuming a slow temporal variation of the percent acceleration rate S̈S -1 of the cosmic scale factor S(t, it is shown that the orbit of a local binary undergoes a secular expansion. To first order in the power expansion of S̈S -1 around the present epoch t0, a non-vanishing shift per orbit (Δr of the two-body relative distance r occurs for eccentric trajectories. A general relativistic expression, which turns out to be cubic in the Hubble parameter H0 at the present epoch, is explicitly calculated for it in the case of matter-dominated epochs with Dark Energy. For a highly eccentric Oort comet orbit with period Pb ≈ 31 Myr, the general relativistic distance shift per orbit turns out to be of the order of (Δr ≈ 70 km. For the Large Magellanic Cloud, assumed on a bound elliptic orbit around the Milky Way, the shift per orbit is of the order of (Δr ≈ 2–4 pc. Our result has a general validity since it holds in any cosmological model admitting the Hubble law and a slowly varying S̈S-1(t. More generally, it is valid for an arbitrary Hooke-like extra-acceleration whose “elastic” parameter κ is slowly time-dependent, irrespectively of the physical mechanism which may lead to it. The coefficient κ1 of the first-order term of the power expansion of κ(t can be preliminarily constrained in a model-independent way down to a κ1 ≲ 2 x 10-13 year-3 level from latest Solar System’s planetary observations. The radial velocities of the double lined spectroscopic binary ALPHA Cen AB yield κ1 ≲ 10-8 year-3.

  17. Effects of Sled Towing on Peak Force, the Rate of Force Development and Sprint Performance During the Acceleration Phase

    Martínez-Valencia María Asunción

    2015-06-01

    Full Text Available Resisted sprint training is believed to increase strength specific to sprinting. Therefore, the knowledge of force output in these tasks is essential. The aim of this study was to analyze the effect of sled towing (10%, 15% and 20% of body mass (Bm on sprint performance and force production during the acceleration phase. Twenty-three young experienced sprinters (17 men and 6 women; men = 17.9 ± 3.3 years, 1.79 ± 0.06 m and 69.4 ± 6.1 kg; women = 17.2 ± 1.7 years, 1.65 ± 0.04 m and 56.6 ± 2.3 kg performed four 30 m sprints from a crouch start. Sprint times in 20 and 30 m sprint, peak force (Fpeak, a peak rate of force development (RFDpeak and time to RFD (TRFD in first step were recorded. Repeated-measures ANOVA showed significant increases (p ≤ 0.001 in sprint times (20 and 30 m sprint for each resisted condition as compared to the unloaded condition. The RFDpeak increased significantly when a load increased (3129.4 ± 894.6 N·s−1, p ≤ 0.05 and 3892.4 ± 1377.9 N·s−1, p ≤ 0.01. Otherwise, no significant increases were found in Fpeak and TRFD. The RFD determines the force that can be generated in the early phase of muscle contraction, and it has been considered a factor that influences performance of force-velocity tasks. The use of a load up to 20% Bm might provide a training stimulus in young sprinters to improve the RFDpeak during the sprint start, and thus, early acceleration.

  18. Evolutionary model with Turing machines

    Feverati, Giovanni; Musso, Fabio

    2008-06-01

    The development of a large noncoding fraction in eukaryotic DNA and the phenomenon of the code bloat in the field of evolutionary computations show a striking similarity. This seems to suggest that (in the presence of mechanisms of code growth) the evolution of a complex code cannot be attained without maintaining a large inactive fraction. To test this hypothesis we performed computer simulations of an evolutionary toy model for Turing machines, studying the relations among fitness and coding versus noncoding ratio while varying mutation and code growth rates. The results suggest that, in our model, having a large reservoir of noncoding states constitutes a great (long term) evolutionary advantage.

  19. Rapid Circumstellar Disk Evolution and an Accelerating Star Formation Rate in the Infrared Dark Cloud M17 SWex

    Povich, Matthew S; Robitaille, Thomas P; Broos, Patrick S; Orbin, Wesley T; King, Robert R; Naylor, Tim; Whitney, Barbara A

    2016-01-01

    We present a catalog of 840 X-ray sources and first results from a 100 ks Chandra X-ray Observatory imaging study of the filamentary infrared dark cloud G014.225$-$00.506, which forms the central regions of a larger cloud complex known as the M17 southwest extension (M17 SWex). In addition to the rich population of protostars and young stellar objects with dusty circumstellar disks revealed by Spitzer Space Telescope archival data, we discover a population of X-ray-emitting, intermediate-mass pre--main-sequence stars (IMPS) that lack infrared excess emission from circumstellar disks. We model the infrared spectral energy distributions of this source population to measure its mass function and place new constraints on the inner dust disk destruction timescales for 2-8 $M_{\\odot}$ stars. We also place a lower limit on the star formation rate (SFR) and find that it is quite high ($\\dot{M}\\ge 0.007~M_{\\odot}$ yr$^{-1}$), equivalent to several Orion Nebula Clusters in G14.225$-$0.506 alone, and likely accelerating...

  20. How competition affects evolutionary rescue

    Osmond, Matthew Miles; de Mazancourt, Claire

    2013-01-01

    Populations facing novel environments can persist by adapting. In nature, the ability to adapt and persist will depend on interactions between coexisting individuals. Here we use an adaptive dynamic model to assess how the potential for evolutionary rescue is affected by intra- and interspecific competition. Intraspecific competition (negative density-dependence) lowers abundance, which decreases the supply rate of beneficial mutations, hindering evolutionary rescue. On the other hand, inters...

  1. Determination of Wall Thinning Rates and High-Risk Zones for Local Wall Thinning due to Flow-Accelerated Corrosion

    Thousands of flow-accelerated corrosion (FAC)-possible zones cause long and costly inspection procedures for nuclear power plants as well as fossil power plants, even if the number of zones is minimized on the basis of temperature and flow velocity. In order to narrow down the number of inspection zones, suitable prediction or estimation procedures for FAC occurrence should be applied and the resulting computer programs tuned with as many inspection data as possible. Such coupling of the estimation and inspection procedures should lead to effective and reliable preparation against FAC occurrence and propagation. A six-step procedure based on three-dimensional (3D) computational fluid dynamics (CFD) codes and a coupled model of electrochemistry and oxide layer growth was proposed to estimate local wall thinning due to FAC and applied to evaluate wall thinning rate, residual lifetimes of the pipes and applicability of countermeasures against FAC. As a result of a V and V (verification and validation method) evaluation based on a comparison of calculated and measured wall thinning, it was confirmed that wall thinning rate could be predicted with an accuracy within a factor of 2 and residual wall thicknesses after one year operation could be estimated with an error less than 20%. In order to mitigate one of the disadvantages of the 3D FAC code which is the large amount of computational time needed, a 1D FAC code was developed by applying 1D mass transfer coefficients and geometry factors. Not only the probability of serious wall thinning occurrence but also a hazard scale for pipe rupture could be analyzed. FAC risk was defined as the mathematical product of the possibility of wall thinning occurrence and its hazard scale. The local maximum thinning rate could be predicted with an accuracy within a factor of 2 with the 1D FAC code. High FAC risk zones along entire cooling systems and the effects of countermeasures on mitigating the risks could be evaluated within a

  2. Evolutionary Information Theory

    Mark Burgin

    2013-01-01

    Evolutionary information theory is a constructive approach that studies information in the context of evolutionary processes, which are ubiquitous in nature and society. In this paper, we develop foundations of evolutionary information theory, building several measures of evolutionary information and obtaining their properties. These measures are based on mathematical models of evolutionary computations, machines and automata. To measure evolutionary information in an invariant form, we const...

  3. Evolutionary Emotion Theory in Second Language Education

    Stern, Joseph

    2014-01-01

    After a long period of neglect, research into emotion has accelerated over the past several decades, producing many findings and theories that could be useful in educational practice. This study focuses on the most recent research into ultimate explanations of affect, which evolutionary psychology, unlike the schools of thought that currently predominate in educational theory, can provide. This study seeks to provide context for an evolutionary view of affect through a survey of emotion th...

  4. HDRMC, an accelerated Monte Carlo dose calculator for high dose rate brachytherapy with CT-compatible applicators

    Chibani, Omar, E-mail: omar.chibani@fccc.edu; C-M Ma, Charlie [Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 (United States)

    2014-05-15

    Purpose: To present a new accelerated Monte Carlo code for CT-based dose calculations in high dose rate (HDR) brachytherapy. The new code (HDRMC) accounts for both tissue and nontissue heterogeneities (applicator and contrast medium). Methods: HDRMC uses a fast ray-tracing technique and detailed physics algorithms to transport photons through a 3D mesh of voxels representing the patient anatomy with applicator and contrast medium included. A precalculated phase space file for the{sup 192}Ir source is used as source term. HDRM is calibrated to calculated absolute dose for real plans. A postprocessing technique is used to include the exact density and composition of nontissue heterogeneities in the 3D phantom. Dwell positions and angular orientations of the source are reconstructed using data from the treatment planning system (TPS). Structure contours are also imported from the TPS to recalculate dose-volume histograms. Results: HDRMC was first benchmarked against the MCNP5 code for a single source in homogenous water and for a loaded gynecologic applicator in water. The accuracy of the voxel-based applicator model used in HDRMC was also verified by comparing 3D dose distributions and dose-volume parameters obtained using 1-mm{sup 3} versus 2-mm{sup 3} phantom resolutions. HDRMC can calculate the 3D dose distribution for a typical HDR cervix case with 2-mm resolution in 5 min on a single CPU. Examples of heterogeneity effects for two clinical cases (cervix and esophagus) were demonstrated using HDRMC. The neglect of tissue heterogeneity for the esophageal case leads to the overestimate of CTV D90, CTV D100, and spinal cord maximum dose by 3.2%, 3.9%, and 3.6%, respectively. Conclusions: A fast Monte Carlo code for CT-based dose calculations which does not require a prebuilt applicator model is developed for those HDR brachytherapy treatments that use CT-compatible applicators. Tissue and nontissue heterogeneities should be taken into account in modern HDR

  5. 分子绝对进化速率与物种分歧时间之间的定量关系%Quantitative analysis of relationship between absolute evolutionary rates and taxa divergence times

    李可群

    2015-01-01

    By studying some protein and nucleotide sequences available from GenBank database in American National Center of Bio -technology Information (NCBI), a quantitative equation was discovered for the relationship between the absolute molecular evolutionary Ea rates and taxa divergence times as follow:lnk =-Rt +lnK0 , where Ea is the activation energy of locus mutation , k0 is extreme absolute molecular evolutionary rate , and R is a constant , its preliminary biological application was discussed .Data analysis also showed that a similar equation is also applicable for the relationship between extreme absolute molecular evolutionary rates and taxa divergence times , which means that the biological molecular evolution process may be under the control of "molecular o′clocks"of sequence locus muta-tion and evolution of taxa extreme molecular evolutionary rates , which can be called as "dual molecular o′clock".%通过对美国国家生物技术信息中心数据库GenBank提供的一些蛋白质和核苷酸序列进行比对和分析,发现生物分子绝对进化速率k与进化时间或物种分歧时间t之间存在下列定量关系:lnk =-Ea Rt +lnK0,式中Ea为位点突变活化能,k0为分子极限绝对进化速率,R为常数,并对其生物学意义进行了初步的探讨;数据分析还揭示出物种的分子极限绝对进化速率与进化时间或物种分歧时间之间也服从相似的定量公式,也就是说生物分子进化过程可能同时受到序列位点突变和控制物种分子极限绝对进化速率进化的两个“分子钟”作用,即存在“双重分子钟”现象。

  6. Evolutionary Information Theory

    Mark Burgin

    2013-04-01

    Full Text Available Evolutionary information theory is a constructive approach that studies information in the context of evolutionary processes, which are ubiquitous in nature and society. In this paper, we develop foundations of evolutionary information theory, building several measures of evolutionary information and obtaining their properties. These measures are based on mathematical models of evolutionary computations, machines and automata. To measure evolutionary information in an invariant form, we construct and study universal evolutionary machines and automata, which form the base for evolutionary information theory. The first class of measures introduced and studied in this paper is evolutionary information size of symbolic objects relative to classes of automata or machines. In particular, it is proved that there is an invariant and optimal evolutionary information size relative to different classes of evolutionary machines. As a rule, different classes of algorithms or automata determine different information size for the same object. The more powerful classes of algorithms or automata decrease the information size of an object in comparison with the information size of an object relative to weaker4 classes of algorithms or machines. The second class of measures for evolutionary information in symbolic objects is studied by introduction of the quantity of evolutionary information about symbolic objects relative to a class of automata or machines. To give an example of applications, we briefly describe a possibility of modeling physical evolution with evolutionary machines to demonstrate applicability of evolutionary information theory to all material processes. At the end of the paper, directions for future research are suggested.

  7. Cycle-Powered Short Radius (1.9 m) Centrifuge: Effect of Exercise Versus Passive Acceleration on Heart Rate in Humans

    Greenleaf, J. E.; Gundo, D. P.; Watenpaugh, D. E.; Mulenburg, G. M.; Mckenzie, M. A.; Looft-Wilson, R.; Hargens, A. R.

    1997-01-01

    In addition to extensive use of lower extremity physical exercise training as a countermeasure for the work capacity component of spaceflight deconditioning, some form of additional head-to-foot (+Gz) gravitational (orthostatic) stress may be required to further attenuate or prevent the signs and symptoms (nausea, vertigo, instability, fatigue) of the general reentry syndrome (GRS) that can reduce astronaut performance during landing. Orthostatic (head-to-foot) stress can be induced by standing, by lower body negative pressure, and by +Gz acceleration. One important question is whether acceleration training alone or with concurrent leg exercise would provide sufficient additive stimulation to attenuate the GRS. Use of a new human-powered centrifuge may be the answer. Thus, the purpose for this study was to compare heart rate (HR), i.e., a stress response during human-powered acceleration, in four men (35-62 yr) and two women (30-31 yr) during exercise acceleration versus passive acceleration (by an off-board operator) at 100% (maximal acceleration = A(max)), and at 25%, 50%, and 75% of A(max). Mean (+/-SE) A(max) was 43.7 +/- 1.3 rpm (+3.9 +/- 0.2Gz). Mean HR at exercise A(max) was 189 +/- 13 b/min (50-70 sec run time), and 142 +/- 22 b/min at passive A(max) (40-70 sec run time). Regression of mean HR on the various +Gz levels indicated explained variance (correlations squared) of r(exp 2) = 0.88 (exercise) and r(exp 2) = 0.96 (passive): exercise HR of 107 +/- 4 (25%) to 189 +/- 13 (100%) b/min were 43-50 b/min higher (p less than 0.05) than comparable passive HR of 64 +/- 2 to 142 +/- 22 b/min. Thus, exercise adds significant physiological stress during +Gz acceleration. Inflight use of this combined exercise and acceleration countermeasure may maintain work capacity as well as normalize acceleration and orthostatic tolerances which could attenuate or perhaps eliminate the GRS.

  8. Doppler-derived acceleration rate of right ventricular early filling as a measurement of right atrial pressure in chronic heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

    Scapellato, F; Eleuteri, E; Temporelli, P L; Imparato, A; Corrà, U; Giannuzzi, P

    1998-02-15

    This study demonstrates that a Doppler-derived tricuspid flow velocity pattern provides an accurate, feasible, and noninvasive method of estimating and monitoring mean right atrial pressure in patients with heart failure due to left ventricular systolic dysfunction, and who are both in sinus rhythm and atrial fibrillation. In particular, the acceleration rate of early right ventricular filling is a powerful and independent predictor of mean right atrial pressure. PMID:9485149

  9. Accelerated tests for the soft error rate determination of single radiation particles in components of terrestrial and avionic electronic systems

    This paper describes the main features of the accelerated test procedures used to determine reliability data of microelectronics devices used in terrestrial environment.This paper focuses on the high energy particle test that could be performed through spallation neutron source or quasi-mono-energetic neutron or proton. Improvements of standards are illustrated with respect to the state of the art of knowledge in radiation effects and scaling down of microelectronics technologies. (authors)

  10. Application of accelerated evaluation method of alteration temperature and constant dose rate irradiation on bipolar linear regulator LM317

    With different irradiation methods including high dose rate irradiation, low dose rate irradiation, alteration temperature and constant dose rate irradiation, and US military standard constant high temperature and constant dose rate irradiation, the ionizing radiation responses of bipolar linear regulator LM317 from three different companies were investigated under the operating and zero biases. The results show that compared with constant high temperature and constant dose rate irradiation method, the alteration temperature and constant dose rate irradiation method can not only very rapidly and accurately evaluate the dose rate effect of three bipolar linear regulators, but also well simulate the damage of low dose rate irradiation. Experiment results make the alteration temperature and constant dose rate irradiation method successfully apply to bipolar linear regulator. (authors)

  11. Diversity Dynamics in Nymphalidae Butterflies: Effect of Phylogenetic Uncertainty on Diversification Rate Shift Estimates

    Peña, Carlos; Espeland, Marianne

    2015-01-01

    The family Nymphalidae is the largest family within the true butterflies and has been used to develop hypotheses explaining evolutionary interactions between plants and insects. Theories of insect and hostplant dynamics predict accelerated diversification in some scenarios. We investigated whether phylogenetic uncertainty affects a commonly used method (MEDUSA, modelling evolutionary diversity using stepwise AIC) for estimating shifts in diversification rates in lineages of the family Nymphal...

  12. Melanin pattern morphs do not differ in metabolic rate: implications for the evolutionary maintenance of a melanophore polymorphism in the green swordtail, Xiphophorus helleri

    Meyer, Christiane I.; Kaufman, Robert; Cech, Joseph J.

    2006-10-01

    Variation in melanin patterns among individuals, populations, and species is common in fishes of the genus Xiphophorus. In the variable platyfish, Xiphophorus variatus, variation in metabolic rate is associated with melanin coloration and the color morphs appear to be physiological specialists adapted to particular environmental conditions. This study investigates whether a melanin polymorphism in the green swordtail, Xiphophorus helleri, is likewise associated with variation in metabolic rate. We measured metabolic rate as oxygen consumption rate of both adult male and juvenile X. helleri in static respirometers. The oxygen consumption rate does not differ significantly between the spotted and nonspotted morphs in either group, suggesting that-unlike in X. variatus-selection on metabolic rate is not involved in maintaining the polymorphism in X. helleri. We suggest that explanations need to be sought for the evolution of melanophore diversity in Xiphophorus that are pertinent to each melanin pattern polymorphism or groups of similar polymorphisms.

  13. Hybridization of evolutionary algorithms

    Fister, Iztok; Mernik, Marjan; Brest, Janez

    2012-01-01

    Evolutionary algorithms are good general problem solver but suffer from a lack of domain specific knowledge. However, the problem specific knowledge can be added to evolutionary algorithms by hybridizing. Interestingly, all the elements of the evolutionary algorithms can be hybridized. In this chapter, the hybridization of the three elements of the evolutionary algorithms is discussed: the objective function, the survivor selection operator and the parameter settings. As an objective function...

  14. Update of the water chemistry effect on the flow-accelerated corrosion rate of carbon steel: influence of hydrazine, boric acid, ammonia, morpholine and ethanolamine

    The influence of the water chemistry on Flow-Accelerated Corrosion (FAC) affecting carbon steel components has been studied for many years and is relatively well known and taken into account by the models. Nonetheless, experimental studies were conducted in the last few years at EDF on the CIROCO loop in order to check the influence of the water chemistry parameters (hydrazine, boric acid, ammonia, morpholine and ethanolamine) on the FAC rate of carbon steel in one phase flow conditions. The hydrazine impact on the FAC rate was shown to be minor in EDF's chemistry recommendation range, compared to other parameters' effects such as the pH effect. The presence of boric acid in the nominal secondary circuit conditions was negligible. Finally, as expected, the nature of the chemical conditioning (ammonia, morpholine or ethanolamine) did not modify the FAC rate, the influencing chemical variable being the at-temperature pH in one-phase flow conditions. (author)

  15. Complexity in Evolutionary Processes

    Darwin's principle of evolution by natural selection is readily casted into a mathematical formalism. Molecular biology revealed the mechanism of mutation and provides the basis for a kinetic theory of evolution that models correct reproduction and mutation as parallel chemical reaction channels. A result of the kinetic theory is the existence of a phase transition in evolution occurring at a critical mutation rate, which represents a localization threshold for the population in sequence space. Occurrence and nature of such phase transitions depend critically on fitness landscapes. The fitness landscape being tantamount to a mapping from sequence or genotype space into phenotype space is identified as the true source of complexity in evolution. Modeling evolution as a stochastic process is discussed and neutrality with respect to selection is shown to provide a major challenge for understanding evolutionary processes (author)

  16. An approximate relation for the prediction of the dose rate from radioactivity induced in high energy particle accelerators

    Sullivan, A H

    1972-01-01

    If the dose rate from radioactivity induced by high energy particle radiation depends on irradiation time T and decay time T according to D=K0log (T+t/T), where 0 is the flux density of high-energy particles causing the activation and K is a constant for any given set of irradiation, target and geometrical conditions, then this paper shows that K can be estimated such that the formula can be used to make absolute dose rate predictions of sufficient accuracy for radiation protection purposes.

  17. Factors Associated With Chest Wall Toxicity After Accelerated Partial Breast Irradiation Using High-Dose-Rate Brachytherapy

    Purpose: The purpose of this analysis was to evaluate dose-volume relationships associated with a higher probability for developing chest wall toxicity (pain) after accelerated partial breast irradiation (APBI) by using both single-lumen and multilumen brachytherapy. Methods and Materials: Rib dose data were available for 89 patients treated with APBI and were correlated with the development of chest wall/rib pain at any point after treatment. Ribs were contoured on computed tomography planning scans, and rib dose-volume histograms (DVH) along with histograms for other structures were constructed. Rib DVH data for all patients were sampled at all volumes ≥0.008 cubic centimeter (cc) (for maximum dose related to pain) and at volumes of 0.5, 1, 2, and 3 cc for analysis. Rib pain was evaluated at each follow-up visit. Patient responses were marked as yes or no. No attempt was made to grade responses. Eighty-nine responses were available for this analysis. Results: Nineteen patients (21.3%) complained of transient chest wall/rib pain at any point in follow-up. Analysis showed a direct correlation between total dose received and volume of rib irradiated with the probability of developing rib/chest wall pain at any point after follow-up. The median maximum dose at volumes ≥0.008 cc of rib in patients who experienced chest wall pain was 132% of the prescribed dose versus 95% of the prescribed dose in those patients who did not experience pain (p = 0.0035). Conclusions: Although the incidence of chest wall/rib pain is quite low with APBI brachytherapy, attempts should be made to keep the volume of rib irradiated at a minimum and the maximum dose received by the chest wall as low as reasonably achievable.

  18. Evolutionary Rent-Seeking

    Hehenkamp, Burkhard; Leininger, Wolfgang; Possajennikov, Alex

    2001-01-01

    Tullock’s analysis of rent-seeking is reconsidered from an evolutionary point of view. We show that evolutionarily stable behavior in a rent-seeking contest differs from efficient rent-seeking behavior in a Nash equilibrium. We explore that implications of evolutionary stability for rent-seeking behavior and relate them to the well examined Nash equilibrium behavior. A most interesting result is an overdissipation law, which holds in evolutionary equilibrium.

  19. Overview: Evolutionary Algorithms

    Bartz-Beielstein, Thomas (Dr.); Mersmann, Olaf

    2014-01-01

    Evolutionary algorithm (EA) is an umbrella term used to describe population-based stochastic direct search algorithms that in some sense mimic natural evolution. Prominent representatives of such algorithms are genetic algorithms, evolution strategies, evolutionary programming, and genetic programming. On the basis of the evolutionary cycle, similarities and differences between these algorithms are described. We briefly discuss how EAs can be adapted to work well in case of multiple objective...

  20. Overview: Evolutionary Algorithms

    Bartz-Beielstein, Thomas (Dr.); Branke, Jürgen; Mehnen, Jörn; Mersmann, Olaf

    2015-01-01

    Evolutionary algorithm (EA) is an umbrella term used to describe population-based stochastic direct search algorithms that in some sense mimic natural evolution. Prominent representatives of such algorithms are genetic algorithms, evolution strategies, evolutionary programming, and genetic programming. On the basis of the evolutionary cycle, similarities and differences between these algorithms are described. We briefly discuss how EAs can be adapted to work well in case of multiple objective...

  1. Accelerated Partial Breast Irradiation With Low-Dose-Rate Interstitial Implant Brachytherapy After Wide Local Excision: 12-Year Outcomes From a Prospective Trial

    Purpose: To evaluate the long-term toxicity, cosmesis, and local control of accelerated partial breast irradiation with implant brachytherapy after wide local excision for Stage T1N0 breast cancer (BCa). Materials and Methods: Between 1997 and 2001, 50 patients with Stage T1N0M0 BCa were treated in a Phase I-II protocol using low-dose-rate accelerated partial breast irradiation with implant brachytherapy after wide local excision and lymph node surgery. The total dose was escalated in three groups: 50 Gy (n = 20), 55 Gy (n = 17), and 60 Gy (n = 13). Patient- and physician-assessed breast cosmesis, patient satisfaction, toxicity, mammographic abnormalities, repeat biopsies, and disease status were prospectively evaluated at each visit. Kendall’s tau (τβ) and logistic regression analyses were used to correlate outcomes with dose, implant volume, patient age, and systemic therapy. Results: The median follow-up period was 11.2 years (range, 4–14). The patient satisfaction rate was 67%, 67% reported good-excellent cosmesis, and 54% had moderate-severe fibrosis. Higher dose was correlated with worse cosmetic outcome (τβ 0.6, p β 0.5, p β 0.4, p = .0024). Of the 50 patients, 35% had fat necrosis and 34% developed telangiectasias ≥1 cm2. Grade 3–4 late skin and subcutaneous toxicities were seen in 4 patients (9%) and 6 patients (13%), respectively, and both correlated with higher dose (τβ 0.3–0.5, p ≤ .01). One patient had Grade 4 skin ulceration and fat necrosis requiring surgery. Mammographic abnormalities were seen in 32% of the patients, and 30% underwent repeat biopsy, of which 73% were benign. Six patients had ipsilateral breast recurrence: five elsewhere in the breast, and one at the implant site. One patient died of metastatic BCa after recurrence. The 12-year actuarial local control, recurrence-free survival, and overall survival rate was 85% (95% confidence interval, 70–97%), 72% (95% confidence interval, 54–86%), and 87% (95% confidence

  2. Accelerated Partial Breast Irradiation With Low-Dose-Rate Interstitial Implant Brachytherapy After Wide Local Excision: 12-Year Outcomes From a Prospective Trial

    Hattangadi, Jona A. [Harvard Radiation Oncology Program, Boston, MA (United States); Powell, Simon N. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); MacDonald, Shannon M.; Mauceri, Thomas; Ancukiewicz, Marek [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Freer, Phoebe [Department of Radiology, Massachusetts General Hospital, Boston, MA (United States); Lawenda, Brian [21st Century Oncology, Las Vegas, NV (United States); Alm El-Din, Mohamed A. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Department of Clinical Oncology, Tanta University Hospital, Tanta (Egypt); Gadd, Michele A.; Smith, Barbara L. [Department of Surgical Oncology, Massachusetts General Hospital, Boston, MA (United States); Taghian, Alphonse G., E-mail: ataghian@partners.org [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States)

    2012-07-01

    Purpose: To evaluate the long-term toxicity, cosmesis, and local control of accelerated partial breast irradiation with implant brachytherapy after wide local excision for Stage T1N0 breast cancer (BCa). Materials and Methods: Between 1997 and 2001, 50 patients with Stage T1N0M0 BCa were treated in a Phase I-II protocol using low-dose-rate accelerated partial breast irradiation with implant brachytherapy after wide local excision and lymph node surgery. The total dose was escalated in three groups: 50 Gy (n = 20), 55 Gy (n = 17), and 60 Gy (n = 13). Patient- and physician-assessed breast cosmesis, patient satisfaction, toxicity, mammographic abnormalities, repeat biopsies, and disease status were prospectively evaluated at each visit. Kendall's tau ({tau}{sub {beta}}) and logistic regression analyses were used to correlate outcomes with dose, implant volume, patient age, and systemic therapy. Results: The median follow-up period was 11.2 years (range, 4-14). The patient satisfaction rate was 67%, 67% reported good-excellent cosmesis, and 54% had moderate-severe fibrosis. Higher dose was correlated with worse cosmetic outcome ({tau}{sub {beta}} 0.6, p < .0001), lower patient satisfaction ({tau}{sub {beta}} 0.5, p < .001), and worse fibrosis ({tau}{sub {beta}} 0.4, p = .0024). Of the 50 patients, 35% had fat necrosis and 34% developed telangiectasias {>=}1 cm{sup 2}. Grade 3-4 late skin and subcutaneous toxicities were seen in 4 patients (9%) and 6 patients (13%), respectively, and both correlated with higher dose ({tau}{sub {beta}} 0.3-0.5, p {<=} .01). One patient had Grade 4 skin ulceration and fat necrosis requiring surgery. Mammographic abnormalities were seen in 32% of the patients, and 30% underwent repeat biopsy, of which 73% were benign. Six patients had ipsilateral breast recurrence: five elsewhere in the breast, and one at the implant site. One patient died of metastatic BCa after recurrence. The 12-year actuarial local control, recurrence

  3. Evolutionary Algorithm Definition

    Nada M.A. AL-Salami

    2009-01-01

    Full Text Available Problem statement: Most resent evolutionary algorithms work under weak theoretical basis and thus, they are computationally expensive. Approach: This study discussed the use of new evolutionary algorithm for automatic programming, based on theoretical definitions of program behaviors. Evolutionary process adapted fixed and self-organized input-output specification of the problem, to evolve good finite state machine that efficiently satisfies these specifications. Results: The proposed algorithm enhanced evolutionary process by simultaneously solving multi-parts from the same problem. Conclusion: The probability that the algorithm will converge to the optimal solution was highly enhanced when decomposing the main problem into multi-part.

  4. Homocysteine-lowering by B vitamins slows the rate of accelerated brain atrophy in mild cognitive impairment: a randomized controlled trial.

    A David Smith

    Full Text Available BACKGROUND: An increased rate of brain atrophy is often observed in older subjects, in particular those who suffer from cognitive decline. Homocysteine is a risk factor for brain atrophy, cognitive impairment and dementia. Plasma concentrations of homocysteine can be lowered by dietary administration of B vitamins. OBJECTIVE: To determine whether supplementation with B vitamins that lower levels of plasma total homocysteine can slow the rate of brain atrophy in subjects with mild cognitive impairment in a randomised controlled trial (VITACOG, ISRCTN 94410159. METHODS AND FINDINGS: Single-center, randomized, double-blind controlled trial of high-dose folic acid, vitamins B(6 and B(12 in 271 individuals (of 646 screened over 70 y old with mild cognitive impairment. A subset (187 volunteered to have cranial MRI scans at the start and finish of the study. Participants were randomly assigned to two groups of equal size, one treated with folic acid (0.8 mg/d, vitamin B(12 (0.5 mg/d and vitamin B(6 (20 mg/d, the other with placebo; treatment was for 24 months. The main outcome measure was the change in the rate of atrophy of the whole brain assessed by serial volumetric MRI scans. RESULTS: A total of 168 participants (85 in active treatment group; 83 receiving placebo completed the MRI section of the trial. The mean rate of brain atrophy per year was 0.76% [95% CI, 0.63-0.90] in the active treatment group and 1.08% [0.94-1.22] in the placebo group (P =  0.001. The treatment response was related to baseline homocysteine levels: the rate of atrophy in participants with homocysteine >13 µmol/L was 53% lower in the active treatment group (P =  0.001. A greater rate of atrophy was associated with a lower final cognitive test scores. There was no difference in serious adverse events according to treatment category. CONCLUSIONS AND SIGNIFICANCE: The accelerated rate of brain atrophy in elderly with mild cognitive impairment can be slowed by treatment

  5. Molluscan Evolutionary Genomics

    Simison, W. Brian; Boore, Jeffrey L.

    2005-12-01

    In the last 20 years there have been dramatic advances in techniques of high-throughput DNA sequencing, most recently accelerated by the Human Genome Project, a program that has determined the three billion base pair code on which we are based. Now this tremendous capability is being directed at other genome targets that are being sampled across the broad range of life. This opens up opportunities as never before for evolutionary and organismal biologists to address questions of both processes and patterns of organismal change. We stand at the dawn of a new 'modern synthesis' period, paralleling that of the early 20th century when the fledgling field of genetics first identified the underlying basis for Darwin's theory. We must now unite the efforts of systematists, paleontologists, mathematicians, computer programmers, molecular biologists, developmental biologists, and others in the pursuit of discovering what genomics can teach us about the diversity of life. Genome-level sampling for mollusks to date has mostly been limited to mitochondrial genomes and it is likely that these will continue to provide the best targets for broad phylogenetic sampling in the near future. However, we are just beginning to see an inroad into complete nuclear genome sequencing, with several mollusks and other eutrochozoans having been selected for work about to begin. Here, we provide an overview of the state of molluscan mitochondrial genomics, highlight a few of the discoveries from this research, outline the promise of broadening this dataset, describe upcoming projects to sequence whole mollusk nuclear genomes, and challenge the community to prepare for making the best use of these data.

  6. Accelerated Stem Growth Rates and Improved Fiber Properties of Loblolly Pine: Functional Analysis Of CyclinD from Pinus taeda

    Dr. John Cairney, School of Biology and Institute of Paper Science and Technology @ Georgia Tech, Georgia Institute of Technology; Dr. Gary Peter, University of Florida; Dr. Ulrika Egertsdotter, Dept. of Forestry, Virgina Tech; Dr. Armin Wagner, New Zealand Forest Research Institute Ltd. (Scion Research.)

    2005-11-30

    A sustained supply of low-cost, high quality raw materials is essential for the future success of the U.S. forest products industry. To maximize stem (trunk) growth, a fundamental understanding of the molecular mechanisms that regulate cell divisions within the cambial meristem is essential. We hypothesize that auxin levels within the cambial meristem regulate cyclin gene expression and this in turn controls cell cycle progression as occurs in all eukaryotic cells. Work with model plant species has shown that ectopic overexpression of cyclins promotes cell division thereby increasing root growth > five times. We intended to test whether ectopic overexpression of cambial cyclins in the cambial zone of loblolly pine also promotes cell division rates that enhance stem growth rates. Results generated in model annual angiosperm systems cannot be reliably extrapolated to perennial gymnosperms, thus while the generation and development of transgenic pine is time consuming, this is the necessary approach for meaningful data. We succeeded in isolating a cyclin D gene and Clustal analysis to the Arabidopsis cyclin D gene family indicates that it is more closely related to cyclin D2 than D1 or D3 Using this gene as a probe we observed a small stimulation of cyclin D expression in somatic embryo culture upon addition of auxin. We hypothesized that trees with more cells in the vascular cambial and expansion zones will have higher cyclin mRNA levels. We demonstrated that in trees under compressive stress where the rates of cambial divisions are increased on the underside of the stem relative to the top or opposite side, there was a 20 fold increase in the level of PtcyclinD1 mRNA on the compressed side of the stem relative to the opposite. This suggests that higher secondary growth rates correlate with PtcyclinD1 expression. We showed that larger diameter trees show more growth during each year and that the increased growth in loblolly pine trees correlates with more cell

  7. Evolutionary food web models in fragmented landscapes

    Allhoff, Korinna Theresa

    2015-01-01

    Ecosystems all over the world currently experience dramatic changes in their environment. The direct consequences are increased extinction rates. Food webs, which are networks of predator-prey interactions, provide a basic understanding of ecosystems and therefore help to identify reasonable conservation strategies. In this thesis, I analyze evolutionary metacommunities, which can be modeled as evolutionary networks of networks: The outer networks represent fragmented landscapes of sever...

  8. The evolutionary emergence of pandemic influenza

    Day, Troy; André, Jean-Baptiste; Park, Andrew

    2006-01-01

    Pandemic influenza remains a serious public health threat and the processes involved in the evolutionary emergence of pandemic influenza strains remain incompletely understood. Here, we develop a stochastic model for the evolutionary emergence of pandemic influenza, and use it to address three main questions. (i) What is the minimum annual number of avian influenza virus infections required in humans to explain the historical rate of pandemic emergence? (ii) Are such avian influenza infection...

  9. Evolutionary humanoid robotics

    Eaton, Malachy

    2015-01-01

    This book examines how two distinct strands of research on autonomous robots, evolutionary robotics and humanoid robot research, are converging. The book will be valuable for researchers and postgraduate students working in the areas of evolutionary robotics and bio-inspired computing.

  10. Evolutionary Justification of Plagiarism

    Karpov, Alexander

    2016-01-01

    This paper provides evolutionary game theoretic model of plagiarism. The paper finds the relationship between author effort, publication value, and the frequency of plagiarism. There are two types of equilibria. Plagiarist-free equilibria are neutrally stable. The only evolutionary stable state is characterized by a positive share of plagiarists.

  11. Evolutionary tracks of massive stars during formation

    Smith, Michael D

    2013-01-01

    A model for massive stars is constructed by piecing together evolutionary algorithms for the protostellar structure, the environment, the inflow and the radiation feedback. We investigate specified accretion histories of constant, decelerating and accelerating forms and consider both hot and cold accretion, identified with spherical free-fall and disk accretion, respectively. Diagnostic tools for the interpretation of the phases of massive star formation and testing the evolutionary models are then developed. Evolutionary tracks able to fit Herschel Space Telescope data require the generated stars to be three to four times less massive than in previous interpretations, thus being consistent with clump star formation efficiencies of $10 -- 15\\%$. However, for these cold Hershel clumps, the bolometric temperature is not a good diagnostic to differentiate between accretion models. We also find that neither spherical nor disk accretion can explain the high radio luminosities of many protostars. Nevertheless, we d...

  12. Polymorphic Evolutionary Games.

    Fishman, Michael A

    2016-06-01

    In this paper, I present an analytical framework for polymorphic evolutionary games suitable for explicitly modeling evolutionary processes in diploid populations with sexual reproduction. The principal aspect of the proposed approach is adding diploid genetics cum sexual recombination to a traditional evolutionary game, and switching from phenotypes to haplotypes as the new game׳s pure strategies. Here, the relevant pure strategy׳s payoffs derived by summing the payoffs of all the phenotypes capable of producing gametes containing that particular haplotype weighted by the pertinent probabilities. The resulting game is structurally identical to the familiar Evolutionary Games with non-linear pure strategy payoffs (Hofbauer and Sigmund, 1998. Cambridge University Press), and can be analyzed in terms of an established analytical framework for such games. And these results can be translated into the terms of genotypic, and whence, phenotypic evolutionary stability pertinent to the original game. PMID:27016340

  13. Implications for electron acceleration and transport from non-thermal electron rates at loop-top and foot-point sources in solar flares

    Simões, Paulo J A

    2013-01-01

    The interrelation of hard X-ray (HXR) emitting sources and the underlying physics of electron acceleration and transport presents one of the major questions in the high energy solar flare physics. Spatially resolved observations of solar flares often demonstrate the presence of well separated sources of bremsstrahlung emission, so-called coronal and foot-point sources. Using spatially resolved X-ray observations by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and recently improved imaging techniques, we investigate in detail the spatially resolved electron distributions in a few well observed solar flares. The selected flares can be interpreted as having a standard geometry with chromospheric HXR foot-point sources related to thick-target X-ray emission and the coronal sources characterised by a combination of thermal and thin-target bremsstrahlung. Using imaging spectroscopy technique, we deduce the characteristic electron rates and spectral indices required to explain the coronal and fo...

  14. On the nature of rate acceleration in the synthesis and fragmentation of triazolines by Brønsted acid: secondary catalysis by water (hydronium triflate).

    Hong, Ki Bum; Donahue, Matthew G; Johnston, Jeffrey N

    2008-02-20

    Rate acceleration of the addition of benzyl azide to an electron deficient olefin is characterized using in situ IR spectroscopy. Under strictly anhydrous conditions and at depressed temperature (-20 degrees C), a triazoline intermediate is selectively formed. The stability of this protonated triazoline intermediate at -20 degrees C is indefinite, but warming of the reaction mixture to 0 degrees C or above results in its conversion to the beta-amino oxazolidine dione observed under conditions used in our earlier report. As an alternative to warming, the same conversion can be effected by the addition of a single equivalent of water. Our experiments collectively demonstrate the metastability of the protonated triazoline intermediate and secondary catalysis of triazolinium ring fragmentation by water. This behavior is attributed to the ability of water to transfer a proton from N3 to N1 of the triazoline, thereby allowing ring fragmentation and nitrogen expulsion. PMID:18217758

  15. Estimation of amount of residual radioactivity in high-energy electron accelerator component by measuring the gamma-ray dose rate

    A simple way is needed to estimate the amount of induced radioactivity in the samples irradiated at high-energy electron accelerators. The gamma-ray dose equivalent at the surface of irradiated materials was calculated using EGS4 Monte Carlo when the residual activity is uniformly distributed in several size of a rectangular parallelepiped made of Al, Fe and concrete. The self-shielding effects for gamma-rays from typical residual nuclei, 22Na, 54Mn, 60Co etc., were studied. When the equivalent dose rate is 1 μSv/h at 10 cm distant from the surface of thick targets, the total amount and concentration of radioactivity were calculated. They were compared with the exemption limits. (author)

  16. Evolutionary Constraints to Viroid Evolution

    Santiago F. Elena

    2009-09-01

    Full Text Available We suggest that viroids are trapped into adaptive peaks as the result of adaptive constraints. The first one is imposed by the necessity to fold into packed structures to escape from RNA silencing. This creates antagonistic epistases, which make future adaptive trajectories contingent upon the first mutation and slow down the rate of adaptation. This second constraint can only be surpassed by increasing genetic redundancy or by recombination. Eigen’s paradox imposes a limit to the increase in genome complexity in the absence of mechanisms reducing mutation rate. Therefore, recombination appears as the only possible route to evolutionary innovation in viroids.

  17. Widespread adaptive evolution during repeated evolutionary radiations in New World lupins

    Nevado, Bruno; Atchison, Guy W.; Hughes, Colin E.; Filatov, Dmitry A.

    2016-01-01

    The evolutionary processes that drive rapid species diversification are poorly understood. In particular, it is unclear whether Darwinian adaptation or non-adaptive processes are the primary drivers of explosive species diversifications. Here we show that repeated rapid radiations within New World lupins (Lupinus, Leguminosae) were underpinned by a major increase in the frequency of adaptation acting on coding and regulatory changes genome-wide. This contrasts with far less frequent adaptation in genomes of slowly diversifying lupins and all other plant genera analysed. Furthermore, widespread shifts in optimal gene expression coincided with shifts to high rates of diversification and evolution of perenniality, a putative key adaptation trait thought to have triggered the evolutionary radiations in New World lupins. Our results reconcile long-standing debate about the relative importance of protein-coding and regulatory evolution, and represent the first unambiguous evidence for the rapid onset of lineage- and genome-wide accelerated Darwinian evolution during rapid species diversification. PMID:27498896

  18. Evolutionary tree reconstruction

    Cheeseman, Peter; Kanefsky, Bob

    1990-01-01

    It is described how Minimum Description Length (MDL) can be applied to the problem of DNA and protein evolutionary tree reconstruction. If there is a set of mutations that transform a common ancestor into a set of the known sequences, and this description is shorter than the information to encode the known sequences directly, then strong evidence for an evolutionary relationship has been found. A heuristic algorithm is described that searches for the simplest tree (smallest MDL) that finds close to optimal trees on the test data. Various ways of extending the MDL theory to more complex evolutionary relationships are discussed.

  19. Can Accelerators Accelerate Learning?

    The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ)[1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

  20. Spatial effect on stochastic dynamics of bistable evolutionary games

    We consider the lifetimes of metastable states in bistable evolutionary games (coordination games), and examine how they are affected by spatial structure. A semiclassical approximation based on a path integral method is applied to stochastic evolutionary game dynamics with and without spatial structure, and the lifetimes of the metastable states are evaluated. It is shown that the population dependence of the lifetimes is qualitatively different in these two models. Our result indicates that spatial structure can accelerate the transitions between metastable states. (paper)

  1. When development matters: From evolutionary psychology to evolutionary developmental psychology

    Hernández Blasi, Carlos; Bjorklund, David F.; Gardiner, Amy K.

    2008-01-01

    This article presents evolutionary developmental psychology (EDP) as an emerging field of evolutionary psychology (EP). In describing the core tenets of both approaches and the differences between them, we emphasize the important roles that evolution and development have in understanding human behaviour. We suggest that developmental psychologists should pay more attention to evolutionary issues and, conversely, evolutionary psychologists should take development seriously ...

  2. Adaptive Evolutionary Clustering

    Xu, Kevin S.; Kliger, Mark; Hero III, Alfred O.

    2011-01-01

    In many practical applications of clustering, the objects to be clustered evolve over time, and a clustering result is desired at each time step. In such applications, evolutionary clustering typically outperforms traditional static clustering by producing clustering results that reflect long-term trends while being robust to short-term variations. Several evolutionary clustering algorithms have recently been proposed, often by adding a temporal smoothness penalty to the cost function of a st...

  3. Evolutionary Theorizing in Economics

    Richard R. Nelson; Winter, Sidney G.

    2002-01-01

    This paper reviews the case for an evolutionary approach to problems of economic analysis, ranging from the details of individual firm behavior in the short run through industrial dynamics to the historical evolution of institutions and technologies. We draw upon a substantial body of recent research contributions. We characterize micro behavior as governed by skills and routines that are shaped by learning and selection. We then consider major areas of application of evolutionary thinking, i...

  4. Music and evolutionary computation

    Reis, Cecília; Marques, Viriato M.; Machado, J. A. Tenreiro

    2011-01-01

    This paper presents a brief history of the western music: from its genesis to serialism and the Darmstadt school. Also some mathematical aspects of music are then presented and confronted with music as a form of art. The question is, are these two distinct aspects compatible? Can computers be of real help in automatic composition? The more appealing algorithmic approach is evolutionary computation as it offers creativity potential. Therefore, the Evolutionary Algorithms are then introduced an...

  5. Applications of Evolutionary Computation

    Squillero, Giovanni

    2015-01-01

    This book constitutes the refereed conference proceedings of the 18th International Conference on the Applications of Evolutionary Computation, EvoApplications 2015, held in Copenhagen, Spain, in April 2015, colocated with the Evo* 2015 events EuroGP, EvoCOP, and EvoMUSART. The 72 revised full papers presented were carefully reviewed and selected from 125 submissions. EvoApplications 2015 consisted of the following 13 tracks: EvoBIO (evolutionary computation, machine learning and data mining ...

  6. Plasma accelerators

    Recently attention has focused on charged particle acceleration in a plasma by a fast, large amplitude, longitudinal electron plasma wave. The plasma beat wave and plasma wakefield accelerators are two efficient ways of producing ultra-high accelerating gradients. Starting with the plasma beat wave accelerator (PBWA) and laser wakefield accelerator (LWFA) schemes and the plasma wakefield accelerator (PWFA) steady progress has been made in theory, simulations and experiments. Computations are presented for the study of LWFA. (author)

  7. Linear Accelerators

    Vretenar, M

    2014-01-01

    The main features of radio-frequency linear accelerators are introduced, reviewing the different types of accelerating structures and presenting the main characteristics aspects of linac beam dynamics.

  8. Application of Overall Dynamic Body Acceleration as a Proxy for Estimating the Energy Expenditure of Grazing Farm Animals: Relationship with Heart Rate

    Masafumi Miwa; Kazato Oishi; Yasuhiro Nakagawa; Hiromichi Maeno; Hiroki Anzai; Hajime Kumagai; Kanji Okano; Hisaya Tobioka; Hiroyuki Hirooka

    2015-01-01

    Estimating the energy expenditure of farm animals at pasture is important for efficient animal management. In recent years, an alternative technique for estimating energy expenditure by measuring body acceleration has been widely performed in wildlife and human studies, but the availability of the technique in farm animals has not yet been examined. In the present study, we tested the potential use of an acceleration index, overall dynamic body acceleration (ODBA), as a new proxy for estimati...

  9. Metabolism at Evolutionary Optimal States

    Iraes Rabbers

    2015-06-01

    Full Text Available Metabolism is generally required for cellular maintenance and for the generation of offspring under conditions that support growth. The rates, yields (efficiencies, adaptation time and robustness of metabolism are therefore key determinants of cellular fitness. For biotechnological applications and our understanding of the evolution of metabolism, it is necessary to figure out how the functional system properties of metabolism can be optimized, via adjustments of the kinetics and expression of enzymes, and by rewiring metabolism. The trade-offs that can occur during such optimizations then indicate fundamental limits to evolutionary innovations and bioengineering. In this paper, we review several theoretical and experimental findings about mechanisms for metabolic optimization.

  10. A Proof, Based on the Euler Sum Acceleration, of the Recovery of an Exponential (Geometric) Rate of Convergence for the Fourier Series of a Function with Gibbs Phenomenon

    Boyd, John P

    2010-01-01

    When a function $f(x)$ is singular at a point $x_{s}$ on the real axis, its Fourier series, when truncated at the $N$-th term, gives a pointwise error of only $O(1/N)$ over the entire real axis. Such singularities spontaneously arise as "fronts" in meteorology and oceanography and "shocks" in other branches of fluid mechanics. It has been previously shown that it is possible to recover an exponential rate of convegence at all points away from the singularity in the sense that $|f(x) - f_{N}^{\\sigma}(x) | \\sim O(\\exp(- q(x) N))$ where $f_{N}^{\\sigma}(x)$ is the result of applying a filter or summability method to the partial sum $f_{N}(x)$ and $q(x)$ is a proportionality constant that is a function of $d(x) \\equiv |x-x_{s}|$, the distance from $x$ to the singularity. Here we give an elementary proof of great generality using conformal mapping in a dummy variable $z$; this is equivalent to applying the Euler acceleration. We show that $q(x) \\approx \\log(\\cos(d(x)/2))$ for the Euler filter when the Fourier perio...

  11. Flame spread over electrical wire with AC electric fields: Internal circulation, fuel vapor-jet, spread rate acceleration, and molten insulator dripping

    Lim, Seungjae

    2015-04-01

    The effect of electric field on the characteristics of flame spread along a polyethylene (PE) insulated electrical wire was investigated experimentally by varying the AC frequency and voltage applied to the wire. The results showed that the flame spread rate was accelerated due to the convergence of electric flux near the end of wire, having three distinct regimes depending on applied voltage. In each regime, several subregimes could be identified depending on AC frequency. Flame shape (height and width) and slanted direction of the spreading flame were influenced differently. Fuel-vapor jets were ejected from the molten PE surface even for the baseline case without the application of an electric field; this could be attributed to the bursting of fuel vapor bubbles generated from internal boiling at the molten PE surface. An internal circulation of molten-PE was also observed as a result of non-uniform heating by the spreading flame. In the high voltage regime with a high AC frequency, excessive dripping of molten PE led to flame extinction.

  12. Proteomics in evolutionary ecology.

    Baer, B; Millar, A H

    2016-03-01

    Evolutionary ecologists are traditionally gene-focused, as genes propagate phenotypic traits across generations and mutations and recombination in the DNA generate genetic diversity required for evolutionary processes. As a consequence, the inheritance of changed DNA provides a molecular explanation for the functional changes associated with natural selection. A direct focus on proteins on the other hand, the actual molecular agents responsible for the expression of a phenotypic trait, receives far less interest from ecologists and evolutionary biologists. This is partially due to the central dogma of molecular biology that appears to define proteins as the 'dead-end of molecular information flow' as well as technical limitations in identifying and studying proteins and their diversity in the field and in many of the more exotic genera often favored in ecological studies. Here we provide an overview of a newly forming field of research that we refer to as 'Evolutionary Proteomics'. We point out that the origins of cellular function are related to the properties of polypeptide and RNA and their interactions with the environment, rather than DNA descent, and that the critical role of horizontal gene transfer in evolution is more about coopting new proteins to impact cellular processes than it is about modifying gene function. Furthermore, post-transcriptional and post-translational processes generate a remarkable diversity of mature proteins from a single gene, and the properties of these mature proteins can also influence inheritance through genetic and perhaps epigenetic mechanisms. The influence of post-transcriptional diversification on evolutionary processes could provide a novel mechanistic underpinning for elements of rapid, directed evolutionary changes and adaptations as observed for a variety of evolutionary processes. Modern state-of the art technologies based on mass spectrometry are now available to identify and quantify peptides, proteins, protein

  13. Teaching evolutionary biology

    Tidon Rosana

    2004-01-01

    Full Text Available Evolutionary Biology integrates several disciplines of Biology in a complex and interactive manner, where a deep understanding of the subject demands knowledge in diverse areas. Since this knowledge is often inaccessible to the majority of specialized professionals, including the teachers, we present some reflections in order to stimulate discussions aimed at the improvement of the conditions of education in this area. We examine the profile of evolutionary teaching in Brazil, based on questionnaires distributed to teachers in Secondary Education in the Federal District, on data provided by the "National Institute for Educational Studies and Research", and on information collected from teachers working in various regions of this country. Issues related to biological misconceptions, curriculum and didactic material are discussed, and some proposals are presented with the objective of aiding discussions aimed at the improvement of the teaching of evolutionary biology.

  14. Human nutrition: evolutionary perspectives.

    Barnicot, N A

    2005-01-01

    In recent decades, much new evidence relating to the ape forerunners of modern humans has come to hand and diet appears to be an important factor. At some stage, there must have been a transition from a largely vegetarian ape diet to a modern human hunting economy providing significant amounts of meat. On an even longer evolutionary time scale the change was more complex. The mechanisms of evolutionary change are now better understood than they were in Darwin's time, thanks largely to great advances in genetics, both experimental and theoretical. It is virtually certain that diet, as a major component of the human environment, must have exerted evolutionary effects, but researchers still have little good evidence. PMID:17393680

  15. Total Integrative Evolutionary Communication

    Nedergaard Thomsen, Ole; Brier, Søren

    2014-01-01

    and, on the other, Peircean biosemiotics. According to Cybersemiotics, language is primarily a creative process of total integrative evolutionary communication. It comprises three evolutionary stages: (1) biological reflexive languaging (the reflexive foundation of social coordination), (2......). In this inclusive hierarchy language games subsume the other stages, and thus human evolutionary communication is primarily a symbolic-conventional practice. It is intertwined with the practice of living, that is, with different life forms, including other forms of semiotic behavior. Together they form a coherent...... biological and socio-cultural practice. The basic “molecule” of the cybersemiotic model of human communication is a dyad between two linguistic cyborgs, alias natural language users. Single human communicators are thus “atoms”. They are hybrids between nature and nurture, manipulating all sorts...

  16. Evolutionary Computation:ao Overview

    HeZhenya; WeiChengjian

    1997-01-01

    Evolutionary computation is a field of simulating evolution on a computer.Both aspects of it ,the problem solving aspect and the aspect of modeling natural evolution,are important.Simulating evolution on a computer results in stochastic optimization techniques that can outperform classical methods of optimization when applied to difficult real-world problems.There are currently four main avenues of research in simulated evolution:genetic algorithms,evolutionary programming,evolution strategies,and genetic programming.This paper presents a brief overview of thd field on evolutionary computation,including some theoretical issues,adaptive mechanisms,improvements,constrained optimizqtion,constrained satisfaction,evolutionary neural networks,evolutionary fuzzy systems,hardware evolution,evolutionary robotics,parallel evolutionary computation,and co-evolutionary models.The applications of evolutionary computation for optimizing system and intelligent information processing in telecommunications are also introduced.

  17. Evolutionary Statistical Procedures

    Baragona, Roberto; Poli, Irene

    2011-01-01

    This proposed text appears to be a good introduction to evolutionary computation for use in applied statistics research. The authors draw from a vast base of knowledge about the current literature in both the design of evolutionary algorithms and statistical techniques. Modern statistical research is on the threshold of solving increasingly complex problems in high dimensions, and the generalization of its methodology to parameters whose estimators do not follow mathematically simple distributions is underway. Many of these challenges involve optimizing functions for which analytic solutions a

  18. Behavior Trees for Evolutionary Robotics.

    Scheper, Kirk Y W; Tijmons, Sjoerd; de Visser, Cornelis C; de Croon, Guido C H E

    2016-01-01

    Evolutionary Robotics allows robots with limited sensors and processing to tackle complex tasks by means of sensory-motor coordination. In this article we show the first application of the Behavior Tree framework on a real robotic platform using the evolutionary robotics methodology. This framework is used to improve the intelligibility of the emergent robotic behavior over that of the traditional neural network formulation. As a result, the behavior is easier to comprehend and manually adapt when crossing the reality gap from simulation to reality. This functionality is shown by performing real-world flight tests with the 20-g DelFly Explorer flapping wing micro air vehicle equipped with a 4-g onboard stereo vision system. The experiments show that the DelFly can fully autonomously search for and fly through a window with only its onboard sensors and processing. The success rate of the optimized behavior in simulation is 88%, and the corresponding real-world performance is 54% after user adaptation. Although this leaves room for improvement, it is higher than the 46% success rate from a tuned user-defined controller. PMID:26606468

  19. Accelerated partial breast irradiation: An analysis of variables associated with late toxicity and long-term cosmetic outcome after high-dose-rate interstitial brachytherapy

    Purpose: To perform a detailed analysis of variables associated with late tissue effects of high-dose-rate (HDR) interstitial brachytherapy accelerated partial breast irradiation (APBI) in a large cohort of patients with prolonged follow-up. Methods and Materials: Beginning in 1995, 75 women with Stage I/II breast cancer were enrolled in identical institutional trials evaluating APBI as monotherapy after lumpectomy. Patients eligible included those with T1-2, N0-1 (≤3 nodes positive), M0 tumors of nonlobular histology with negative surgical margins, no extracapsular nodal extension, and negative results on postexcision mammogram. All patients underwent surgical excision and postoperative irradiation with HDR interstitial brachytherapy. The planning target volume was defined as the excision cavity plus a 2-cm margin. Treatment was delivered with a high-activity Ir-192 source at 3.4 Gy per fraction twice daily for 5 days to a total dose of 34 Gy. Dosimetric analyses were performed with three-dimensional postimplant dose and volume reconstructions. All patients were evaluated at 3-6-month intervals and assessed with a standardized cosmetic rating scale and according to Radiation Therapy Oncology Group late normal tissue toxicity scoring criteria. Clinical and therapy-related features were analyzed for their relationship to cosmetic outcome and toxicity rating. Clinical features analyzed included age, volume of resection, history of diabetes or hypertension, extent of axillary surgery, and systemic therapies. Therapy-related features analyzed included volume of tissue encompassed by the 100%, 150%, and 200% isodose lines (V100, V150, and V200, respectively), the dose homogeneity index (DHI), number of source dwell positions, and planar separation. Results: The median follow-up of all patients was 73 months (range, 43-118 months). The cosmetic outcome at last follow-up was rated as excellent, good, and fair/poor in 67%, 24%, and 9% of patients, respectively

  20. Anticancer compound ABT-263 accelerates apoptosis in virus-infected cells and imbalances cytokine production and lowers survival rates of infected mice.

    Kakkola, L; Denisova, O V; Tynell, J; Viiliäinen, J; Ysenbaert, T; Matos, R C; Nagaraj, A; Ohman, T; Kuivanen, S; Paavilainen, H; Feng, L; Yadav, B; Julkunen, I; Vapalahti, O; Hukkanen, V; Stenman, J; Aittokallio, T; Verschuren, E W; Ojala, P M; Nyman, T; Saelens, X; Dzeyk, K; Kainov, D E

    2013-01-01

    ABT-263 and its structural analogues ABT-199 and ABT-737 inhibit B-cell lymphoma 2 (Bcl-2), BCL2L1 long isoform (Bcl-xL) and BCL2L2 (Bcl-w) proteins and promote cancer cell death. Here, we show that at non-cytotoxic concentrations, these small molecules accelerate the deaths of non-cancerous cells infected with influenza A virus (IAV) or other viruses. In particular, we demonstrate that ABT-263 altered Bcl-xL interactions with Bcl-2 antagonist of cell death (Bad), Bcl-2-associated X protein (Bax), uveal autoantigen with coiled-coil domains and ankyrin repeats protein (UACA). ABT-263 thereby activated the caspase-9-mediated mitochondria-initiated apoptosis pathway, which, together with the IAV-initiated caspase-8-mediated apoptosis pathway, triggered the deaths of IAV-infected cells. Our results also indicate that Bcl-xL, Bcl-2 and Bcl-w interact with pattern recognition receptors (PRRs) that sense virus constituents to regulate cellular apoptosis. Importantly, premature killing of IAV-infected cells by ABT-263 attenuated the production of key pro-inflammatory and antiviral cytokines. The imbalance in cytokine production was also observed in ABT-263-treated IAV-infected mice, which resulted in an inability of the immune system to clear the virus and eventually lowered the survival rates of infected animals. Thus, the results suggest that the chemical inhibition of Bcl-xL, Bcl-2 and Bcl-w could potentially be hazardous for cancer patients with viral infections. PMID:23887633

  1. Evolutionary Theories of Detection

    Fitch, J P

    2005-04-29

    Current, mid-term and long range technologies for detection of pathogens and toxins are briefly described in the context of performance metrics and operational scenarios. Predictive (evolutionary) and speculative (revolutionary) assessments are given with trade-offs identified, where possible, among competing performance goals.

  2. Part E: Evolutionary Computation

    2015-01-01

    Part E, Evolutionary Computation, edited by Professors Frank Neumann, Carsten Witt, Peter Merz, Carlos A. Coello Coello, Oliver Schütze, Thomas Bartz-Beielstein, Jörn Mehnen, and Günther Raidl, concerns the third fundamental element of what is traditionally being considered to be the core of Comp...

  3. Origins of evolutionary transitions

    Ellen Clarke

    2014-04-01

    An `evolutionary transition in individuality’ or `major transition’ is a transformation in the hierarchical level at which natural selection operates on a population. In this article I give an abstract (i.e. level-neutral and substrate-neutral) articulation of the transition process in order to precisely understand how such processes can happen, especially how they can get started.

  4. Recent Advances in Evolutionary Computation

    Xin Yao; Yong Xu

    2006-01-01

    Evolutionary computation has experienced a tremendous growth in the last decade in both theoretical analyses and industrial applications. Its scope has evolved beyond its original meaning of "biological evolution" toward a wide variety of nature inspired computational algorithms and techniques, including evolutionary, neural, ecological, social and economical computation, etc., in a unified framework. Many research topics in evolutionary computation nowadays are not necessarily "evolutionary". This paper provides an overview of some recent advances in evolutionary computation that have been made in CERCIA at the University of Birmingham, UK. It covers a wide range of topics in optimization, learning and design using evolutionary approaches and techniques, and theoretical results in the computational time complexity of evolutionary algorithms. Some issues related to future development of evolutionary computation are also discussed.

  5. An evolutionary model with Turing machines

    Feverati, Giovanni

    2007-01-01

    The development of a large non-coding fraction in eukaryotic DNA and the phenomenon of the code-bloat in the field of evolutionary computations show a striking similarity. This seems to suggest that (in the presence of mechanisms of code growth) the evolution of a complex code can't be attained without maintaining a large inactive fraction. To test this hypothesis we performed computer simulations of an evolutionary toy model for Turing machines, studying the relations among fitness and coding/non-coding ratio while varying mutation and code growth rates. The results suggest that, in our model, having a large reservoir of non-coding states constitutes a great (long term) evolutionary advantage.

  6. EVOLUTIONARY FOUNDATIONS FOR MOLECULAR MEDICINE

    Nesse, Randolph M.; Ganten, Detlev; Gregory, T. Ryan; Omenn, Gilbert S.

    2012-01-01

    Evolution has long provided a foundation for population genetics, but many major advances in evolutionary biology from the 20th century are only now being applied in molecular medicine. They include the distinction between proximate and evolutionary explanations, kin selection, evolutionary models for cooperation, and new strategies for tracing phylogenies and identifying signals of selection. Recent advances in genomics are further transforming evolutionary biology and creating yet more oppo...

  7. Future accelerators (?)

    I describe the future accelerator facilities that are currently foreseen for electroweak scale physics, neutrino physics, and nuclear structure. I will explore the physics justification for these machines, and suggest how the case for future accelerators can be made

  8. Future accelerators (?)

    John Womersley

    2003-08-21

    I describe the future accelerator facilities that are currently foreseen for electroweak scale physics, neutrino physics, and nuclear structure. I will explore the physics justification for these machines, and suggest how the case for future accelerators can be made.

  9. Evolutionary computation in stochastic environments

    Schmidt, Christian

    2007-01-01

    This book develops efficient methods for the application of Evolutionary Algorithms on stochastic problems. To achieve this, procedures for statistical selection are systematically analyzed with respect to different measures and significantly improved. It is shown how to adapt one of the best procedures for the needs of Evolutionary Algorithms and Evolutionary operators for efficient implementation in stochastic environments are identified.

  10. Accelerating Value Creation with Accelerators

    Jonsson, Eythor Ivar

    2015-01-01

    accelerator programs. Microsoft runs accelerators in seven different countries. Accelerators have grown out of the infancy stage and are now an accepted approach to develop new ventures based on cutting-edge technology like the internet of things, mobile technology, big data and virtual reality. It is also......Accelerators can help to accelerate value creation. Accelerators are short-term programs that have the objective of creating innovative and fast growing ventures. They have gained attraction as larger corporations like Microsoft, Barclays bank and Nordea bank have initiated and sponsored...

  11. Evolutionary status of Entamoeba

    DONG Jiuhong; WEN Jianfan; XIN Dedong; LU Siqi

    2004-01-01

    In addition to its medical importance as parasitic pathogen, Entamoeba has aroused people's interest in its evolutionary status for a long time. Lacking mitochondrion and other intracellular organelles common to typical eukaryotes, Entamoeba and several other amitochondrial protozoans have been recognized as ancient pre-mitochondriate eukaryotes and named "archezoa", the most primitive extant eukaryotes. It was suggested that they might be living fossils that remained in a primitive stage of evolution before acquisition of organelles, lying close to the transition between prokaryotes and eukaryotes. However, recent studies revealed that Entamoeba contained an organelle, "crypton" or "mitosome", which was regarded as specialized or reductive mitochondrion. Relative molecular phylogenetic analyses also indicated the existence or the probable existence of mitochondrion in Entamoeba. Our phylogenetic analysis based on DNA topoisomerase II strongly suggested its divergence after some mitchondriate eukaryotes. Here, all these recent researches are reviewed and the evolutionary status of Entamoeba is discussed.

  12. Evolutionary constrained optimization

    Deb, Kalyanmoy

    2015-01-01

    This book makes available a self-contained collection of modern research addressing the general constrained optimization problems using evolutionary algorithms. Broadly the topics covered include constraint handling for single and multi-objective optimizations; penalty function based methodology; multi-objective based methodology; new constraint handling mechanism; hybrid methodology; scaling issues in constrained optimization; design of scalable test problems; parameter adaptation in constrained optimization; handling of integer, discrete and mix variables in addition to continuous variables; application of constraint handling techniques to real-world problems; and constrained optimization in dynamic environment. There is also a separate chapter on hybrid optimization, which is gaining lots of popularity nowadays due to its capability of bridging the gap between evolutionary and classical optimization. The material in the book is useful to researchers, novice, and experts alike. The book will also be useful...

  13. Evolutionary Design in Embryogeny

    Ashlock, Daniel

    In biology texts embryogeny is defined as "the development or production of an embryo." An embryo is a living creature in its first stage of life, from the fertilized egg cell through the initial development of its morphology and its chemical networks. The study of embryogeny is part of developmental biology [1, 2]. The reader may wonder why a book on evolutionary design should have a section on embryogeny. Computational embryogeny is the study of representations for evolutionary computation that mimic biological embryogeny. These representations contain analogs to the complex biological processes that steer a single cell to become a rose, a mouse, or a man. The advantage of using embryogenic representations is their richness of expression. A small seed of information can be expanded, through a developmental process, into a complex and potentially useful object. This richness of expression comes at a substantial price: the developmental process is sufficiently complex to be unpredictable.

  14. The Evolutionary Origins of Hierarchy.

    Mengistu, Henok; Huizinga, Joost; Mouret, Jean-Baptiste; Clune, Jeff

    2016-06-01

    Hierarchical organization-the recursive composition of sub-modules-is ubiquitous in biological networks, including neural, metabolic, ecological, and genetic regulatory networks, and in human-made systems, such as large organizations and the Internet. To date, most research on hierarchy in networks has been limited to quantifying this property. However, an open, important question in evolutionary biology is why hierarchical organization evolves in the first place. It has recently been shown that modularity evolves because of the presence of a cost for network connections. Here we investigate whether such connection costs also tend to cause a hierarchical organization of such modules. In computational simulations, we find that networks without a connection cost do not evolve to be hierarchical, even when the task has a hierarchical structure. However, with a connection cost, networks evolve to be both modular and hierarchical, and these networks exhibit higher overall performance and evolvability (i.e. faster adaptation to new environments). Additional analyses confirm that hierarchy independently improves adaptability after controlling for modularity. Overall, our results suggest that the same force-the cost of connections-promotes the evolution of both hierarchy and modularity, and that these properties are important drivers of network performance and adaptability. In addition to shedding light on the emergence of hierarchy across the many domains in which it appears, these findings will also accelerate future research into evolving more complex, intelligent computational brains in the fields of artificial intelligence and robotics. PMID:27280881

  15. Evolutionary economics and psychology

    Witt, Ulrich

    2006-01-01

    Evolutionary economics is a paradigm for explaining the transformation of the economy. To achieve its goal, it needs being founded on a proper theory of economic behavior. The paper discusses these foundations. It is argued that the historical malleability of economic behavior is based on the interactions between innate behavior dispositions and adaptation mechanisms on the one hand and the limited, and always selective, cognitive and observational learning that contributes to an ever more ex...

  16. Learning in evolutionary environments

    Dosi, Giovanni; Marengo, Luigi; Fagiolo, Giogio

    2001-01-01

    The purpose of this work is to present a sort of short selective guide to an enormous and diverse literature on learning processes in economics. We argue that learning is an ubiquitous characteristic of most economic and social systems but it acquires even greater importance in explicitly evolutionary environments where: a) heterogeneous agents systematically display various forms of "bounded rationality"; b) there is a persistent appearance of novelties, both as exogenous shocks and as the r...

  17. Evolutionary game design

    Browne, Cameron

    2011-01-01

    The book describes the world's first successful experiment in fully automated board game design. Evolutionary methods were used to derive new rule sets within a custom game description language, and self-play trials used to estimate each derived game's potential to interest human players. The end result is a number of new and interesting games, one of which has proved popular and gone on to be commercially published.

  18. Evolutionary genomics of Entamoeba

    Weedall, Gareth D.; Hall, Neil

    2011-01-01

    Entamoeba histolytica is a human pathogen that causes amoebic dysentery and leads to significant morbidity and mortality worldwide. Understanding the genome and evolution of the parasite will help explain how, when and why it causes disease. Here we review current knowledge about the evolutionary genomics of Entamoeba: how differences between the genomes of different species may help explain different phenotypes, and how variation among E. histolytica parasites reveals patterns of population ...

  19. Evolutionary health psychology

    Dickins, Thomas E.

    2006-01-01

    For the last decade and a half the discipline of Evolutionary Psychology (EP) has been developing with great success. The first collection of significant papers was published in 1992 (Barkow et al.) and recently a landmark handbook has been produced summing the progress so far, as well as setting an agenda for future study (Buss, 2005). Unlike other areas within Psychology, EP extends its interest to all behaviours, rightly seeing them as part of an evolved phenotype, and health has not escap...

  20. Introduction to Evolutionary Algorithms

    Yu, Xinjie

    2010-01-01

    Evolutionary algorithms (EAs) are becoming increasingly attractive for researchers from various disciplines, such as operations research, computer science, industrial engineering, electrical engineering, social science, economics, etc. This book presents an insightful, comprehensive, and up-to-date treatment of EAs, such as genetic algorithms, differential evolution, evolution strategy, constraint optimization, multimodal optimization, multiobjective optimization, combinatorial optimization, evolvable hardware, estimation of distribution algorithms, ant colony optimization, particle swarm opti

  1. Asymmetric Evolutionary Games.

    McAvoy, Alex; Hauert, Christoph

    2015-08-01

    Evolutionary game theory is a powerful framework for studying evolution in populations of interacting individuals. A common assumption in evolutionary game theory is that interactions are symmetric, which means that the players are distinguished by only their strategies. In nature, however, the microscopic interactions between players are nearly always asymmetric due to environmental effects, differing baseline characteristics, and other possible sources of heterogeneity. To model these phenomena, we introduce into evolutionary game theory two broad classes of asymmetric interactions: ecological and genotypic. Ecological asymmetry results from variation in the environments of the players, while genotypic asymmetry is a consequence of the players having differing baseline genotypes. We develop a theory of these forms of asymmetry for games in structured populations and use the classical social dilemmas, the Prisoner's Dilemma and the Snowdrift Game, for illustrations. Interestingly, asymmetric games reveal essential differences between models of genetic evolution based on reproduction and models of cultural evolution based on imitation that are not apparent in symmetric games. PMID:26308326

  2. Acceleration performance of individual European sea bass Dicentrarchus labrax measured with a sprint performance chamber: comparison with high-speed cinematography and correlates with ecological performance.

    Vandamm, Joshua P; Marras, Stefano; Claireaux, Guy; Handelsman, Corey A; Nelson, Jay A

    2012-01-01

    Locomotor performance can influence the ecological and evolutionary success of a species. For fish, favorable outcomes of predator-prey encounters are often presumably due to robust acceleration ability. Although escape-response or "fast-start" studies utilizing high-speed cinematography are prevalent, little is known about the contribution of relative acceleration performance to ecological or evolutionary success in a species. This dearth of knowledge may be due to the time-consuming nature of analyzing film, which imposes a practical limit on sample sizes. Herein, we present a high-throughput potential alternative for measuring fish acceleration performance using a sprint performance chamber (SPC). The acceleration performance of a large number of juvenile European sea bass (Dicentrarchus labrax) from two populations was analyzed. Animals from both hatchery and natural ontogenies were assessed, and animals of known acceleration ability had their ecological performance measured in a mesocosm environment. Individuals from one population also had their acceleration performance assessed by both high-speed cinematography and an SPC. Acceleration performance measured in an SPC was lower than that measured by classical high-speed video techniques. However, short-term repeatability and interindividual variation of acceleration performance were similar between the two techniques, and the SPC recorded higher sprint swimming velocities. Wild fish were quicker to accelerate in an SPC and had significantly greater accelerations than all groups of hatchery-raised fish. Acceleration performance had no significant effect on ecological performance (as assessed through animal growth and survival in the mesocosms). However, it is worth noting that wild animals did survive predation in the mesocosm better than farmed ones. Moreover, the hatchery-originated fish that survived the mesocosm experiment, when no predators were present, displayed significantly increased acceleration

  3. Laser accelerator

    Vigil, Ricardo

    2014-01-01

    Approved for public release; distribution is unlimited In 1979,W. B. Colson and S. K. Ride proposed a new kind of electron accelerator using a uniform magnetic field in combination with a circularly-polarized laser field. A key concept is to couple the oscillating electric field to the electron’s motion so that acceleration is sustained. This dissertation investigates the performance of the proposed laser accelerator using modern high powered lasers and mag-netic fields that are significan...

  4. Microsporidian genome analysis reveals evolutionary strategies for obligate intracellular growth.

    Cuomo, Christina A; Desjardins, Christopher A; Bakowski, Malina A; Goldberg, Jonathan; Ma, Amy T; Becnel, James J; Didier, Elizabeth S; Fan, Lin; Heiman, David I; Levin, Joshua Z; Young, Sarah; Zeng, Qiandong; Troemel, Emily R

    2012-12-01

    Microsporidia comprise a large phylum of obligate intracellular eukaryotes that are fungal-related parasites responsible for widespread disease, and here we address questions about microsporidia biology and evolution. We sequenced three microsporidian genomes from two species, Nematocida parisii and Nematocida sp1, which are natural pathogens of Caenorhabditis nematodes and provide model systems for studying microsporidian pathogenesis. We performed deep sequencing of transcripts from a time course of N. parisii infection. Examination of pathogen gene expression revealed compact transcripts and a dramatic takeover of host cells by Nematocida. We also performed phylogenomic analyses of Nematocida and other microsporidian genomes to refine microsporidian phylogeny and identify evolutionary events of gene loss, acquisition, and modification. In particular, we found that all microsporidia lost the tumor-suppressor gene retinoblastoma, which we speculate could accelerate the parasite cell cycle and increase the mutation rate. We also found that microsporidia acquired transporters that could import nucleosides to fuel rapid growth. In addition, microsporidian hexokinases gained secretion signal sequences, and in a functional assay these were sufficient to export proteins out of the cell; thus hexokinase may be targeted into the host cell to reprogram it toward biosynthesis. Similar molecular changes appear during formation of cancer cells and may be evolutionary strategies adopted independently by microsporidia to proliferate rapidly within host cells. Finally, analysis of genome polymorphisms revealed evidence for a sexual cycle that may provide genetic diversity to alleviate problems caused by clonal growth. Together these events may explain the emergence and success of these diverse intracellular parasites. PMID:22813931

  5. Accelerators for energy production

    A tremendous progress of accelerators for these several decades, has been motivated mainly by the research on subnuclear physics. The culmination in high energy accelerators might be SSC, 20 TeV collider in USA, probably the ultimate accelerator being built with the conventional principle. The technology cultivated and integrated for the accelerator development, can now stably offer the high power beam which could be used for the energy problems. The Inertial Confinement Fusion (ICF) with high current, 10 kA and short pulse, 20 ns heavy ion beam (HIB) of mass number ∼200, would be the most promising application of accelerators for energy production. In this scenario, the fuel containing D-T mixture, will be compressed to the high temperature, ∼10 keV and to the high density state, ∼1000 times the solid density with the pressure of ablative plasma or thermal X ray produced by bombarding of high power HIB. The efficiency, beam power/electric power for accelerator, and the repetition rate of HIB accelerators could be most suitable for the energy production. In the present paper, the outline of HIB ICF (HIF) is presented emphasizing the key issues of high current heavy ion accelerator system. (author)

  6. Statistical correlation of the soil incubation and the accelerated laboratory extraction methods to estimate nitrogen release rates of slow- and controlled-release fertilizers.

    Medina, L Carolina; Sartain, Jerry; Obreza, Thomas; Hall, William L; Thiex, Nancy J

    2014-01-01

    Several technologies have been proposed to characterize the nutrient release patterns of enhanced-efficiency fertilizers (EEFs) during the last few decades. These technologies have been developed mainly by manufacturers and are product-specific based on the regulation and analysis of each EEF product. Despite previous efforts to characterize nutrient release of slow-release fertilizer (SRF) and controlled-release fertilizer (CRF) materials, no official method exists to assess their nutrient release patterns. However, the increased production and distribution of EEFs in specialty and nonspecialty markets requires an appropriate method to verify nutrient claims and material performance. Nonlinear regression was used to establish a correlation between the data generated from a 180-day soil incubation-column leaching procedure and 74 h accelerated lab extraction method, and to develop a model that can predict the 180-day nitrogen (N) release curve for a specific SRF and CRF product based on the data from the accelerated laboratory extraction method. Based on the R2 > 0.90 obtained for most materials, results indicated that the data generated from the 74 h accelerated lab extraction method could be used to predict N release from the selected materials during 180 days, including those fertilizers that require biological activity for N release. PMID:25051612

  7. Evolutionary Psychology: The Academic Debate

    Suplizio, Jean

    2005-01-01

    This dissertation examines the academic debate that surrounds the new field called "Evolutionary Psychology." Evolutionary psychology has emerged as the most popular successor theory to human sociobiology. Its proponents search for evolved psychological mechanisms and emphasize universal features of the human mind. My thesis is that in order to flourish evolutionary psychologists must engage other researchers on equal terms -- something they have not been doing. To show this, I examine the...

  8. Theoretical Aspects of Evolutionary Algorithms

    Wegener, Ingo

    2001-01-01

    Randomized search heuristics like simulated annealing and evolutionary algorithms are applied successfully in many different situations. However, the theory on these algorithms is still in its infancy. Here it is discussed how and why such a theory should be developed. Afterwards, some fundamental results on evolutionary algorithms are presented in order to show how theoretical results on randomized search heuristics can be proved and how they contribute to the understanding of evolutionary a...

  9. Evolutionary algorithms in multiobjective problems

    Syomkin, A. M.; Zmitrovich, A. I.

    2003-01-01

    Many real-world problems involve two types of difficulties: 1) multiple, conflicting objectives and 2) a highly complex search space. Efficient evolutionary strategies have been developed to deal with both types of difficulties. Evolutionary algorithms possess several characteristics such as parallelism and robustness that make them preferable to classical optimization methods. In this work 1 conducted comparative studies among the well-known evolutionary algorithms based on NP-hard 0-1 multi...

  10. Binary Evolutionary Models

    Han, Z

    2008-01-01

    In this talk, we present the general principles of binary evolution and give two examples. The first example is the formation of subdwarf B stars (sdBs) and their application to the long-standing problem of ultraviolet excess (also known as UV-upturn) in elliptical galaxies. The second is for the progenitors of type Ia supernovae (SNe Ia). We discuss the main binary interactions, i.e., stable Roche lobe overflow (RLOF) and common envelope (CE) evolution, and show evolutionary channels leading to the formation of various binary-related objects. In the first example, we show that the binary model of sdB stars of Han et al. (2002, 2003) can reproduce field sdB stars and their counterparts, extreme horizontal branch (EHB) stars, in globular clusters. By applying the binary model to the study of evolutionary population synthesis, we have obtained an ``a priori'' model for the UV-upturn of elliptical galaxies and showed that the UV-upturn is most likely resulted from binary interactions. This has major implications...

  11. Testing for Independence between Evolutionary Processes.

    Behdenna, Abdelkader; Pothier, Joël; Abby, Sophie S; Lambert, Amaury; Achaz, Guillaume

    2016-09-01

    Evolutionary events co-occurring along phylogenetic trees usually point to complex adaptive phenomena, sometimes implicating epistasis. While a number of methods have been developed to account for co-occurrence of events on the same internal or external branch of an evolutionary tree, there is a need to account for the larger diversity of possible relative positions of events in a tree. Here we propose a method to quantify to what extent two or more evolutionary events are associated on a phylogenetic tree. The method is applicable to any discrete character, like substitutions within a coding sequence or gains/losses of a biological function. Our method uses a general approach to statistically test for significant associations between events along the tree, which encompasses both events inseparable on the same branch, and events genealogically ordered on different branches. It assumes that the phylogeny and themapping of branches is known without errors. We address this problem from the statistical viewpoint by a linear algebra representation of the localization of the evolutionary events on the tree.We compute the full probability distribution of the number of paired events occurring in the same branch or in different branches of the tree, under a null model of independence where each type of event occurs at a constant rate uniformly inthephylogenetic tree. The strengths andweaknesses of themethodare assessed via simulations;we then apply the method to explore the loss of cell motility in intracellular pathogens. PMID:27208890

  12. Diversity dynamics in Nymphalidae butterflies: effect of phylogenetic uncertainty on diversification rate shift estimates.

    Carlos Peña

    Full Text Available The species rich butterfly family Nymphalidae has been used to study evolutionary interactions between plants and insects. Theories of insect-hostplant dynamics predict accelerated diversification due to key innovations. In evolutionary biology, analysis of maximum credibility trees in the software MEDUSA (modelling evolutionary diversity using stepwise AIC is a popular method for estimation of shifts in diversification rates. We investigated whether phylogenetic uncertainty can produce different results by extending the method across a random sample of trees from the posterior distribution of a Bayesian run. Using the MultiMEDUSA approach, we found that phylogenetic uncertainty greatly affects diversification rate estimates. Different trees produced diversification rates ranging from high values to almost zero for the same clade, and both significant rate increase and decrease in some clades. Only four out of 18 significant shifts found on the maximum clade credibility tree were consistent across most of the sampled trees. Among these, we found accelerated diversification for Ithomiini butterflies. We used the binary speciation and extinction model (BiSSE and found that a hostplant shift to Solanaceae is correlated with increased net diversification rates in Ithomiini, congruent with the diffuse cospeciation hypothesis. Our results show that taking phylogenetic uncertainty into account when estimating net diversification rate shifts is of great importance, as very different results can be obtained when using the maximum clade credibility tree and other trees from the posterior distribution.

  13. Diversity dynamics in Nymphalidae butterflies: effect of phylogenetic uncertainty on diversification rate shift estimates.

    Peña, Carlos; Espeland, Marianne

    2015-01-01

    The species rich butterfly family Nymphalidae has been used to study evolutionary interactions between plants and insects. Theories of insect-hostplant dynamics predict accelerated diversification due to key innovations. In evolutionary biology, analysis of maximum credibility trees in the software MEDUSA (modelling evolutionary diversity using stepwise AIC) is a popular method for estimation of shifts in diversification rates. We investigated whether phylogenetic uncertainty can produce different results by extending the method across a random sample of trees from the posterior distribution of a Bayesian run. Using the MultiMEDUSA approach, we found that phylogenetic uncertainty greatly affects diversification rate estimates. Different trees produced diversification rates ranging from high values to almost zero for the same clade, and both significant rate increase and decrease in some clades. Only four out of 18 significant shifts found on the maximum clade credibility tree were consistent across most of the sampled trees. Among these, we found accelerated diversification for Ithomiini butterflies. We used the binary speciation and extinction model (BiSSE) and found that a hostplant shift to Solanaceae is correlated with increased net diversification rates in Ithomiini, congruent with the diffuse cospeciation hypothesis. Our results show that taking phylogenetic uncertainty into account when estimating net diversification rate shifts is of great importance, as very different results can be obtained when using the maximum clade credibility tree and other trees from the posterior distribution. PMID:25830910

  14. A solvable model of the evolutionary loop

    Peliti, L.

    1998-12-01

    A model for the evolution of a finite population in a rugged fitness landscape is introduced and solved. The population is trapped in an evolutionary loop, alternating periods of stasis to periods in which it performs adaptive walks. The dependence of the average rarity of the population (a quantity related to the fitness of the most adapted individual) and of the duration of stases on population size and mutation rate is calculated.

  15. A solvable model of the evolutionary loop

    Peliti, Luca

    1998-01-01

    A model for the evolution of a finite population in a rugged fitness landscape is introduced and solved. The population is trapped in an evolutionary loop, alternating periods of stasis to periods in which it performs adaptive walks. The dependence of the average rarity of the population (a quantity related to the fitness of the most adapted individual) and of the duration of stases on population size and mutation rate is calculated.

  16. Virulence in malaria: an evolutionary viewpoint.

    Margaret J Mackinnon; Andrew F Read

    2004-01-01

    Malaria parasites cause much morbidity and mortality to their human hosts. From our evolutionary perspective, this is because virulence is positively associated with parasite transmission rate. Natural selection therefore drives virulence upwards, but only to the point where the cost to transmission caused by host death begins to outweigh the transmission benefits. In this review, we summarize data from the laboratory rodent malaria model, Plasmodium chabaudi, and field data on the human mala...

  17. Distributed Evolutionary Computation using REST

    Castillo, P A; Mora, A M; Laredo, J L J; Romero, G; Rivas, V M; Merelo, J J

    2011-01-01

    This paper analises distributed evolutionary computation based on the Representational State Transfer (REST) protocol, which overlays a farming model on evolutionary computation. An approach to evolutionary distributed optimisation of multilayer perceptrons (MLP) using REST and language Perl has been done. In these experiments, a master-slave based evolutionary algorithm (EA) has been implemented, where slave processes evaluate the costly fitness function (training a MLP to solve a classification problem). Obtained results show that the parallel version of the developed programs obtains similar or better results using much less time than the sequential version, obtaining a good speedup.

  18. LIBO accelerates

    2002-01-01

    The prototype module of LIBO, a linear accelerator project designed for cancer therapy, has passed its first proton-beam acceleration test. In parallel a new version - LIBO-30 - is being developed, which promises to open up even more interesting avenues.

  19. Induction accelerators

    Takayama, Ken

    2011-01-01

    A broad class of accelerators rests on the induction principle whereby the accelerating electrical fields are generated by time-varying magnetic fluxes. Particularly suitable for the transport of bright and high-intensity beams of electrons, protons or heavy ions in any geometry (linear or circular) the research and development of induction accelerators is a thriving subfield of accelerator physics. This text is the first comprehensive account of both the fundamentals and the state of the art about the modern conceptual design and implementation of such devices. Accordingly, the first part of the book is devoted to the essential features of and key technologies used for induction accelerators at a level suitable for postgraduate students and newcomers to the field. Subsequent chapters deal with more specialized and advanced topics.

  20. Proterozoic and early Cambrian protists: evidence for accelerating evolutionary tempo.

    Knoll, Andrew

    1994-01-01

    In rocks of late Paleoproterozoic and Mesoproterozoic age (ca. 1700-1000 million years ago), probable eukaryotic microfossils are widespread and well preserved, but assemblage and global diversities are low and turnover is slow. Near the Mesoproterozoic-Neoproterozoic boundary (1000 million years ago), red, green, and chromophytic algae diversified; molecular phylogenies suggest that this was part of a broader radiation of ''higher'' eukaryotic phyla. Observed diversity levels for protistan m...

  1. Evolutionary Computation for Realizing Distillation Separation Sequence Optimization Synthesis

    Dong Hongguang; Qin Limin; Wang Kefeng; Yao Pingjing

    2005-01-01

    Evolutionary algorithm is applied for distillation separation sequence optimization synthesis problems with combination explosion. The binary tree data structure is used to describe the distillation separation sequence, and it is directly applied as the coding method. Genetic operators, which ensure to prohibit illegal filial generations completely, are designed by using the method of graph theory. The crossover operator based on a single parent or two parents is designed successfully. The example shows that the average ratio of search space from evolutionary algorithm with two-parent genetic operation is lower, whereas the rate of successful minimizations from evolutionary algorithm with single parent genetic operation is higher.

  2. Terahertz-driven linear electron acceleration

    Nanni, Emilio Alessandro; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Miller, R J Dwayne; Kärtner, Franz X

    2014-01-01

    The cost, size and availability of electron accelerators is dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency (RF) accelerating structures operate with 30-50 MeV/m gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional RF structures. However, laser-driven electron accelerators require intense sources and suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here, we demonstrate the first linear acceleration of electrons with keV energy gain using optically-generated terahertz (THz) pulses. THz-driven accelerating structures enable high-gradient electron accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. Increasing the operational frequency of accelerators into the THz band allows for greatly increased accelerating ...

  3. Spore: Spawning Evolutionary Misconceptions?

    Bean, Thomas E.; Sinatra, Gale M.; Schrader, P. G.

    2010-10-01

    The use of computer simulations as educational tools may afford the means to develop understanding of evolution as a natural, emergent, and decentralized process. However, special consideration of developmental constraints on learning may be necessary when using these technologies. Specifically, the essentialist (biological forms possess an immutable essence), teleological (assignment of purpose to living things and/or parts of living things that may not be purposeful), and intentionality (assumption that events are caused by an intelligent agent) biases may be reinforced through the use of computer simulations, rather than addressed with instruction. We examine the video game Spore for its depiction of evolutionary content and its potential to reinforce these cognitive biases. In particular, we discuss three pedagogical strategies to mitigate weaknesses of Spore and other computer simulations: directly targeting misconceptions through refutational approaches, targeting specific principles of scientific inquiry, and directly addressing issues related to models as cognitive tools.

  4. Towards an evolutionary model of transcription networks.

    Dan Xie

    2011-06-01

    Full Text Available DNA evolution models made invaluable contributions to comparative genomics, although it seemed formidable to include non-genomic features into these models. In order to build an evolutionary model of transcription networks (TNs, we had to forfeit the substitution model used in DNA evolution and to start from modeling the evolution of the regulatory relationships. We present a quantitative evolutionary model of TNs, subjecting the phylogenetic distance and the evolutionary changes of cis-regulatory sequence, gene expression and network structure to one probabilistic framework. Using the genome sequences and gene expression data from multiple species, this model can predict regulatory relationships between a transcription factor (TF and its target genes in all species, and thus identify TN re-wiring events. Applying this model to analyze the pre-implantation development of three mammalian species, we identified the conserved and re-wired components of the TNs downstream to a set of TFs including Oct4, Gata3/4/6, cMyc and nMyc. Evolutionary events on the DNA sequence that led to turnover of TF binding sites were identified, including a birth of an Oct4 binding site by a 2nt deletion. In contrast to recent reports of large interspecies differences of TF binding sites and gene expression patterns, the interspecies difference in TF-target relationship is much smaller. The data showed increasing conservation levels from genomic sequences to TF-DNA interaction, gene expression, TN, and finally to morphology, suggesting that evolutionary changes are larger at molecular levels and smaller at functional levels. The data also showed that evolutionarily older TFs are more likely to have conserved target genes, whereas younger TFs tend to have larger re-wiring rates.

  5. A Simple General Model of Evolutionary Dynamics

    Thurner, Stefan

    Evolution is a process in which some variations that emerge within a population (of, e.g., biological species or industrial goods) get selected, survive, and proliferate, whereas others vanish. Survival probability, proliferation, or production rates are associated with the "fitness" of a particular variation. We argue that the notion of fitness is an a posteriori concept in the sense that one can assign higher fitness to species or goods that survive but one can generally not derive or predict fitness per se. Whereas proliferation rates can be measured, fitness landscapes, that is, the inter-dependence of proliferation rates, cannot. For this reason we think that in a physical theory of evolution such notions should be avoided. Here we review a recent quantitative formulation of evolutionary dynamics that provides a framework for the co-evolution of species and their fitness landscapes (Thurner et al., 2010, Physica A 389, 747; Thurner et al., 2010, New J. Phys. 12, 075029; Klimek et al., 2009, Phys. Rev. E 82, 011901 (2010). The corresponding model leads to a generic evolutionary dynamics characterized by phases of relative stability in terms of diversity, followed by phases of massive restructuring. These dynamical modes can be interpreted as punctuated equilibria in biology, or Schumpeterian business cycles (Schumpeter, 1939, Business Cycles, McGraw-Hill, London) in economics. We show that phase transitions that separate phases of high and low diversity can be approximated surprisingly well by mean-field methods. We demonstrate that the mathematical framework is suited to understand systemic properties of evolutionary systems, such as their proneness to collapse, or their potential for diversification. The framework suggests that evolutionary processes are naturally linked to self-organized criticality and to properties of production matrices, such as their eigenvalue spectra. Even though the model is phrased in general terms it is also practical in the sense

  6. Evolutionary Model of the Growth and Size of Firms

    Joachim Kaldasch

    2012-01-01

    The key idea of this model is that firms are the result of an evolutionary process. Based on demand and supply considerations the evolutionary model presented here derives explicitly Gibrat's law of proportionate effects as the result of the competition between products. Applying a preferential attachment mechanism for firms the theory allows to establish the size distribution of products and firms. Also established are the growth rate and price distribution of consumer goods. Taking into acc...

  7. Two Aspects of Evolutionary Algorithms

    2000-01-01

    In this paper we discuss the paradigm of evolutionary algorithms (Eas). We argue about the need for new heuristics in real-world problem solving, discussing reasons why some problems are difficult tosolve. After introducing the main concepts of evolutionary algorithms, we concentrate on two issues:(1)self-adaptation of the parameters of EA, and (2) handling constraints.

  8. Open Issues in Evolutionary Robotics.

    Silva, Fernando; Duarte, Miguel; Correia, Luís; Oliveira, Sancho Moura; Christensen, Anders Lyhne

    2016-01-01

    One of the long-term goals in evolutionary robotics is to be able to automatically synthesize controllers for real autonomous robots based only on a task specification. While a number of studies have shown the applicability of evolutionary robotics techniques for the synthesis of behavioral control, researchers have consistently been faced with a number of issues preventing the widespread adoption of evolutionary robotics for engineering purposes. In this article, we review and discuss the open issues in evolutionary robotics. First, we analyze the benefits and challenges of simulation-based evolution and subsequent deployment of controllers versus evolution on real robotic hardware. Second, we discuss specific evolutionary computation issues that have plagued evolutionary robotics: (1) the bootstrap problem, (2) deception, and (3) the role of genomic encoding and genotype-phenotype mapping in the evolution of controllers for complex tasks. Finally, we address the absence of standard research practices in the field. We also discuss promising avenues of research. Our underlying motivation is the reduction of the current gap between evolutionary robotics and mainstream robotics, and the establishment of evolutionary robotics as a canonical approach for the engineering of autonomous robots. PMID:26581015

  9. Evolutionary transitions in bacterial symbiosis

    Sachs, Joel L.; Skophammer, Ryan G.; Regus, John U.

    2011-01-01

    Diverse bacterial lineages form beneficial infections with eukaryotic hosts. The origins, evolution, and breakdown of these mutualisms represent important evolutionary transitions. To examine these key events, we synthesize data from diverse interactions between bacteria and eukaryote hosts. Five evolutionary transitions are investigated, including the origins of bacterial associations with eukaryotes, the origins and subsequent stable maintenance of bacterial mutualism with hosts, the captur...

  10. Topics of Evolutionary Computation 2001

    Ursem, Rasmus Kjær

    This booklet contains the student reports from the course: Topics of Evolutionary Computation, Fall 2001, given by Thiemo Krink, Rene Thomsen and Rasmus K. Ursem......This booklet contains the student reports from the course: Topics of Evolutionary Computation, Fall 2001, given by Thiemo Krink, Rene Thomsen and Rasmus K. Ursem...

  11. Evolutionary Design of Boolean Functions

    WANG Zhang-yi; ZHANG Huan-guo; QIN Zhong-ping; MENG Qing-shu

    2005-01-01

    We use evolutionary computing to synthesize Boolean functions randomly. By using specific crossover and mutation operator in evolving process and modifying search space and fitness function, we get some high non-linearity functions which have other good cryptography characteristics such as autocorrelation etc. Comparing to other heuristic search techniques, evolutionary computing approach is more effective because of global search strategy and implicit parallelism.

  12. Chaos Synthesis by Evolutionary Algorithms

    Zelinka, I.; Chen, G.; Čelikovský, Sergej

    Berlin : Springer-Verlag, 2010 - (Zelinka, I.; Čelikovský, S.; Richter, H.; Chen, G.), s. 345-382 ISBN 978-3-642-10706-1. - (Studies in Computational Intelligence. 267) Institutional research plan: CEZ:AV0Z10750506 Keywords : chaos synthesis * evolutionary algorithms * self organizingmigrating * evolutionary computing Subject RIV: BC - Control Systems Theory

  13. Evolutionary Explanations of Eating Disorders

    Igor Kardum

    2008-12-01

    Full Text Available This article reviews several most important evolutionary mechanisms that underlie eating disorders. The first part clarifies evolutionary foundations of mental disorders and various mechanisms leading to their development. In the second part selective pressures and evolved adaptations causing contemporary epidemic of obesity as well as differences in dietary regimes and life-style between modern humans and their ancestors are described. Concerning eating disorders, a number of current evolutionary explanations of anorexia nervosa are presented together with their main weaknesses. Evolutionary explanations of eating disorders based on the reproductive suppression hypothesis and its variants derived from kin selection theory and the model of parental manipulation were elaborated. The sexual competition hypothesis of eating disorder, adapted to flee famine hypothesis as well as explanation based on the concept of social attention holding power and the need to belonging were also explained. The importance of evolutionary theory in modern conceptualization and research of eating disorders is emphasized.

  14. HIV evolutionary dynamics within and among hosts.

    Lemey, Philippe; Rambaut, Andrew; Pybus, Oliver G

    2006-01-01

    The HIV evolutionary processes continuously unfold, leaving a measurable footprint in viral gene sequences. A variety of statistical models and inference techniques have been developed to reconstruct the HIV evolutionary history and to investigate the population genetic processes that shape viral diversity. Remarkably different population genetic forces are at work within and among hosts. Population-level HIV phylogenies are mainly shaped by selectively neutral epidemiologic processes, implying that genealogy-based population genetic inference can be useful to study the HIV epidemic history. Such evolutionary analyses have shed light on the origins of HIV, and on the epidemic spread of viral variants in different geographic locations and in different populations. The HIV genealogies reconstructed from within-host sequences indicate the action of selection pressure. In addition, recombination has a significant impact on HIV genetic diversity. Accurately quantifying both the adaptation rate and the population recombination rate of HIV will contribute to a better understanding of immune escape and drug resistance. Characterizing the impact of HIV transmission on viral genetic diversity will be a key factor in reconciling the different population genetic processes within and among hosts. PMID:17078483

  15. Earthquake accelerogram simulation with statistical law of evolutionary power spectrum

    ZHANG Cui-ran; CHEN Hou-qun; LI Min

    2007-01-01

    By using the technique for evolutionary power spectrum proposed by Nakayama and with reference to the Kameda formula, an evolutionary spectrum prediction model for given earthquake magnitude and distance is established based on the 80 near-source acceleration records at rock surface with large magnitude from the ground motion database of western U.S.. Then a new iteration method is developed for generation of random accelerograms non-stationary both in amplitude and frequency which are compatible with target evolutionary spectrum. The phase spectra of those simulated accelerograms are also non-stationary in time and frequency domains since the interaction between amplitude and phase angle has been considered during the generation. Furthermore, the sign of the phase spectrum increment is identified to accelerate the iteration. With the proposed statistical model for predicting evolutionary power spectra and the new method for generating compatible time history, the artificial random earthquake accelerograms non-stationary both in amplitude and frequency for certain magnitude and distance can be provided.

  16. Evolutionary Computation Techniques for Predicting Atmospheric Corrosion

    Amine Marref

    2013-01-01

    Full Text Available Corrosion occurs in many engineering structures such as bridges, pipelines, and refineries and leads to the destruction of materials in a gradual manner and thus shortening their lifespan. It is therefore crucial to assess the structural integrity of engineering structures which are approaching or exceeding their designed lifespan in order to ensure their correct functioning, for example, carrying ability and safety. An understanding of corrosion and an ability to predict corrosion rate of a material in a particular environment plays a vital role in evaluating the residual life of the material. In this paper we investigate the use of genetic programming and genetic algorithms in the derivation of corrosion-rate expressions for steel and zinc. Genetic programming is used to automatically evolve corrosion-rate expressions while a genetic algorithm is used to evolve the parameters of an already engineered corrosion-rate expression. We show that both evolutionary techniques yield corrosion-rate expressions that have good accuracy.

  17. Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial

    A David Smith; Smith, Stephen M.; de Jager, Celeste A.; Philippa Whitbread; Carole Johnston; Grzegorz Agacinski; Abderrahim Oulhaj; Bradley, Kevin M.; Robin Jacoby; Helga Refsum

    2010-01-01

    BACKGROUND: An increased rate of brain atrophy is often observed in older subjects, in particular those who suffer from cognitive decline. Homocysteine is a risk factor for brain atrophy, cognitive impairment and dementia. Plasma concentrations of homocysteine can be lowered by dietary administration of B vitamins. OBJECTIVE: To determine whether supplementation with B vitamins that lower levels of plasma total homocysteine can slow the rate of brain atrophy in subjects with mild cognitive im...

  18. Accelerating Universe and Event Horizon

    He, Xiao-Gang(INPAC, SKLPPC and Department of Physics, Shanghai Jiao Tong University, Shanghai, China)

    2001-01-01

    It has been argued in the literature that if a universe is expanding with an accelerating rate indefinitely, it presents a challenge to string theories due to the existence of event horizons. We study the fate of a currently accelerating universe. We show that the universe will continue to accelerate indefinitely if the parameter $\\omega = p/\\rho$ of the equation of state is a constant, no matter how many different types of energy (matter, radiation, quintessence, cosmological constant and et...

  19. Modeling tumor evolutionary dynamics

    Beatriz eStransky

    2013-02-01

    Full Text Available Tumorigenesis can be seen as an evolutionary process, in which the transformation of a normal cell into a tumor cell involves a number of limiting genetic and epigenetic events, occurring in a series of discrete stages. However, not all mutations in a cell are directly involved in cancer development and it is likely that most of them (passenger mutations do not contribute in any way to tumorigenesis. Moreover, the process of tumor evolution is punctuated by selection of advantageous (driver mutations and clonal expansions. Regarding these driver mutations, it is uncertain how many limiting events are required and / or sufficient to promote a tumorigenic process or what are the values associated with the adaptive advantage of different driver mutations. In spite of the availability of high-quality cancer data, several assumptions about the mechanistic process of cancer initiation and development remain largely untested, both mathematically and statistically. Here we review the development of mathematical/computational models where some assumptions were tested and discuss the impact of these models to the field of tumor biology.

  20. Evolutionary tracks for Betelgeuse

    Dolan, Michelle M; Lam, Doan Duc; Lan, Nguyen Quynh; Herczeg, Gregory J; Dearborn, David S P

    2014-01-01

    We have constructed a series of non-rotating quasi-hydrostatic evolutionary models for the M2 Iab supergiant Betelgeuse ($\\alpha~Orionis$). Our models are constrained by multiple values for the observed temperature, luminosity, surface composition and mass loss for this star, along with the parallax distance and high resolution imagery that determines its radius. We have then applied our best-fit models to analyze the observed variations in surface luminosity and the size of detected surface bright spots as the result of up-flowing convective material from regions of high temperature in a surface convective zone. We also attempt to explain the intermittently observed periodic variability in a simple radial linear adiabatic pulsation model. Based upon the best fit to all observed data, we suggest a best progenitor mass estimate of $ 20 ^{+5}_{-3} M_\\odot$ and a current lifetime of $8.0 - 8.5$ Myr based upon the observed ejected mass while on the giant branch.

  1. Industrial Applications of Evolutionary Algorithms

    Sanchez, Ernesto; Tonda, Alberto

    2012-01-01

    This book is intended as a reference both for experienced users of evolutionary algorithms and for researchers that are beginning to approach these fascinating optimization techniques. Experienced users will find interesting details of real-world problems, and advice on solving issues related to fitness computation, modeling and setting appropriate parameters to reach optimal solutions. Beginners will find a thorough introduction to evolutionary computation, and a complete presentation of all evolutionary algorithms exploited to solve different problems. The book could fill the gap between the

  2. Tandem accelerators

    After the installation of Ti-acceleration tubes and substantial modifications and additions to the EN tandem accelerator the performance of the machine has stabilized. The voltage behaviour of the tubes obviously improves as conditioning times necessary to run up to 6 MV decrease. A gridded lens has been added at the entrance of the first acceleration tube, and a second foil stripper is now installed in the short dead section between the high-energy tubes. The MP tandem also has been running stably during most of the year. However, beam instabilities originating from the last tube section and wear problems at the low-energy set of pelletron-chains caused some loss of beam time. During the fall, one set of pelletron charging chains has to be replaced after 49,000 hours of operation. In the course of the year, the MP and the EN tandem accelerators finished their 100,000th and 150,000th hours of operations, respectively. Preparations for the installation of the 3 MV negative heavy ion injector for the MP are progressing steadily. External beam transport, terminal ion optics, and data acquisition and control systems are to a major extent completed; the integration of the terminal power supplies has started. After the final assembly of the accelerator column structure, first voltage runs can be performed. (orig.)

  3. Can reading rate acceleration improve error monitoring and cognitive abilities underlying reading in adolescents with reading difficulties and in typical readers?

    Horowitz-Kraus, Tzipi; Breznitz, Zvia

    2014-01-28

    Dyslexia is characterized by slow, inaccurate reading and by deficits in executive functions. The deficit in reading is exemplified by impaired error monitoring, which can be specifically shown through neuroimaging, in changes in Error-/Correct-related negativities (ERN/CRN). The current study aimed to investigate whether a reading intervention program (Reading Acceleration Program, or RAP) could improve overall reading, as well as error monitoring and other cognitive abilities underlying reading, in adolescents with reading difficulties. Participants with reading difficulties and typical readers were trained with the RAP for 8 weeks. Their reading and error monitoring were characterized both behaviorally and electrophysiologically through a lexical decision task. Behaviorally, the reading training improved "contextual reading speed" and decreased reading errors in both groups. Improvements were also seen in speed of processing, memory and visual screening. Electrophysiologically, ERN increased in both groups following training, but the increase was significantly greater in the participants with reading difficulties. Furthermore, an association between the improvement in reading speed and the change in difference between ERN and CRN amplitudes following training was seen in participants with reading difficulties. These results indicate that improving deficits in error monitoring and speed of processing are possible underlying mechanisms of the RAP intervention. We suggest that ERN is a good candidate for use as a measurement in evaluating the effect of reading training in typical and disabled readers. PMID:24316242

  4. Thomas Edison Accelerated Elementary School.

    Levin, Henry M.; Chasin, Gene

    This paper describes early outcomes of a Sacramento, California, elementary school that participated in the Accelerated Schools Project. The school, which serves many minority and poor students, began training for the project in 1992. Accelerated Schools were designed to advance the learning rate of students through a gifted and talented approach,…

  5. Evolutionary computation for reinforcement learning

    S. Whiteson

    2012-01-01

    Algorithms for evolutionary computation, which simulate the process of natural selection to solve optimization problems, are an effective tool for discovering high-performing reinforcement-learning policies. Because they can automatically find good representations, handle continuous action spaces, a

  6. Evolutionary Processes and Mental Deficiency

    Spitz, Herman H.

    1973-01-01

    The author hypothesizes that central nervous system damage of deficiency associated with mental retardation affects primarily those cortical processes which developed at a late stage in man's evolutionary history. (Author)

  7. Accelerating structures pre-stripping section the milac heavy ion linear Accelerator MILAC

    Researches on development of new variants of accelerating structures for acceleration of the ions with A/q=20 in pre-stripping section PSS-20 are carried out. On an initial part of acceleration of ions from 6 up to 150 keV/u high capture in process of acceleration of the injected ions is provided interdigital (IH) accelerating structure with Radio-Frequency Quadrupole (RFQ) focusing. On the second part of acceleration of ions from 150 keV/u up to 1 MeV/u the highest rate of acceleration is created interdigital (IH) accelerating structure with drift tubes with the modified radio-frequency focusing.

  8. Evolutionary plant physiology: Charles Darwin's forgotten synthesis

    Kutschera, Ulrich; Niklas, Karl J.

    2009-11-01

    Charles Darwin dedicated more than 20 years of his life to a variety of investigations on higher plants (angiosperms). It has been implicitly assumed that these studies in the fields of descriptive botany and experimental plant physiology were carried out to corroborate his principle of descent with modification. However, Darwin’s son Francis, who was a professional plant biologist, pointed out that the interests of his father were both of a physiological and an evolutionary nature. In this article, we describe Darwin’s work on the physiology of higher plants from a modern perspective, with reference to the following topics: circumnutations, tropisms and the endogenous oscillator model; the evolutionary patterns of auxin action; the root-brain hypothesis; phloem structure and photosynthesis research; endosymbioses and growth-promoting bacteria; photomorphogenesis and phenotypic plasticity; basal metabolic rate, the Pfeffer-Kleiber relationship and metabolic optimality theory with respect to adaptive evolution; and developmental constraints versus functional equivalence in relationship to directional natural selection. Based on a review of these various fields of inquiry, we deduce the existence of a Darwinian (evolutionary) approach to plant physiology and define this emerging scientific discipline as the experimental study and theoretical analysis of the functions of green, sessile organisms from a phylogenetic perspective.

  9. Breaking evolutionary constraint with a tradeoff ratchet.

    de Vos, Marjon G J; Dawid, Alexandre; Sunderlikova, Vanda; Tans, Sander J

    2015-12-01

    Epistatic interactions can frustrate and shape evolutionary change. Indeed, phenotypes may fail to evolve when essential mutations are only accessible through positive selection if they are fixed simultaneously. How environmental variability affects such constraints is poorly understood. Here, we studied genetic constraints in fixed and fluctuating environments using the Escherichia coli lac operon as a model system for genotype-environment interactions. We found that, in different fixed environments, all trajectories that were reconstructed by applying point mutations within the transcription factor-operator interface became trapped at suboptima, where no additional improvements were possible. Paradoxically, repeated switching between these same environments allows unconstrained adaptation by continuous improvements. This evolutionary mode is explained by pervasive cross-environmental tradeoffs that reposition the peaks in such a way that trapped genotypes can repeatedly climb ascending slopes and hence, escape adaptive stasis. Using a Markov approach, we developed a mathematical framework to quantify the landscape-crossing rates and show that this ratchet-like adaptive mechanism is robust in a wide spectrum of fluctuating environments. Overall, this study shows that genetic constraints can be overcome by environmental change and that cross-environmental tradeoffs do not necessarily impede but also, can facilitate adaptive evolution. Because tradeoffs and environmental variability are ubiquitous in nature, we speculate this evolutionary mode to be of general relevance. PMID:26567153

  10. Two evolutionary lineages: Machiavellian and Bohrian intelligence

    Skopec, Robert

    2007-01-01

    Two evolutionary lineages: Machiavellian and Bohrian intelligence Mutation and natural selection are the two most basic processes of evolution, yet the study of their interplay remains a challenge for theoretical and empirical research. Darwinian evolution favors genotypes with high replication rates, a process called survival of the fittest representing lineage of the Machiavellian inteligence. According to quasi-species theory, selection favors the cloud of genotypes, interconnected by mutation, whose average replication rate is highest: mutation acts as a selective agent to shape the entire genome so that is robust with respect to mutation. Thus survival of the flattest and inventivest representing lineage of the Bohrian intelligence at high mutation rates. Quasi-species theory predicts that, under appropriate conditions (high mutation pressure), such a mutation can be fixed in an evolving population, despite its lower replication rate.

  11. Dose volume histogram analysis of normal structures associated with accelerated partial breast irradiation delivered by high dose rate brachytherapy and comparison with whole breast external beam radiotherapy fields

    Mutyala Subhakar

    2008-11-01

    Full Text Available Abstract Purpose To assess the radiation dose delivered to the heart and ipsilateral lung during accelerated partial breast brachytherapy using a MammoSite™ applicator and compare to those produced by whole breast external beam radiotherapy (WBRT. Materials and methods Dosimetric analysis was conducted on patients receiving MammoSite breast brachytherapy following conservative surgery for invasive ductal carcinoma. Cardiac dose was evaluated for patients with left breast tumors with a CT scan encompassing the entire heart. Lung dose was evaluated for patients in whom the entire lung was scanned. The prescription dose of 3400 cGy was 1 cm from the balloon surface. MammoSite dosimetry was compared to simulated WBRT fields with and without radiobiological correction for the effects of dose and fractionation. Dose parameters such as the volume of the structure receiving 10 Gy or more (V10 and the dose received by 20 cc of the structure (D20, were calculated as well as the maximum and mean doses received. Results Fifteen patients were studied, five had complete lung data and six had left-sided tumors with complete cardiac data. Ipsilateral lung volumes ranged from 925–1380 cc. Cardiac volumes ranged from 337–551 cc. MammoSite resulted in a significantly lower percentage lung V30 and lung and cardiac V20 than the WBRT fields, with and without radiobiological correction. Conclusion This study gives low values for incidental radiation received by the heart and ipsilateral lung using the MammoSite applicator. The volume of heart and lung irradiated to clinically significant levels was significantly lower with the MammoSite applicator than using simulated WBRT fields of the same CT data sets. Trial registration Dana Farber Trial Registry number 03-179

  12. Lifetime learning in evolutionary robotics

    Ruud, Else-Line Malene

    2015-01-01

    Inspired by animals ability to learn and adapt to changes in their environment during life, hybrid evolutionary algorithms which include local optimization between generations have been developed and successfully applied in a number of research areas. Despite the possible benefits this kind of algorithm could have in the field of evolutionary robotics, very little research has been done on this topic. This thesis explores the effects of learning used in cooperation with a genetic algorithm t...

  13. Coevolution Evolutionary Algorithm: A Survey

    Jeniefer Kavetha. M

    2013-01-01

    Evolutionary Computing techniques have become one of the most powerful tools for solving optimization problems and isbased on the mechanisms of natural selection and genetics. In Evolutionary Algorithm, Co-evolution is a natural choice for learning in problem domains where one agent’s behaviour is directly related to the behaviour of other agents. Co-evolution provides a framework to implement search heuristics that are more elaborate than those driving the exploration of the state space in c...

  14. Counterpunishment revisited: an evolutionary approach

    Wolff, Irenaeus

    2009-01-01

    Evolutionary game theory has shown that in environments characterised by a social-dilemma situation punishment may be an adaptive behaviour. Experimental evidence closely corresponds to this finding but yields contradictory results on the cooperation-enhancing effect of punishment if players are allowed to retaliate against their punishers. The present study sets out to examine the question of whether cooperation will still be part of an evolutionary stable strategy if we allow for counterpun...

  15. Freud: the first evolutionary psychologist?

    LeCroy, D

    2000-04-01

    An evolutionary perspective on attachment theory and psychoanalytic theory brings these two fields together in interesting ways. Application of the evolutionary principle of parent-offspring conflict to attachment theory suggests that attachment styles represent context-sensitive, evolved (adaptive) behaviors. In addition, an emphasis on offspring counter-strategies to adult reproductive strategies leads to consideration of attachment styles as overt manifestations of psychodynamic mediating processes, including the defense mechanisms of repression and reaction formation. PMID:10818628

  16. Evolutionary Explanations of Eating Disorders

    Igor Kardum; Asmir Gračanin; Jasna Hudek-Knežević

    2008-01-01

    This article reviews several most important evolutionary mechanisms that underlie eating disorders. The first part clarifies evolutionary foundations of mental disorders and various mechanisms leading to their development. In the second part selective pressures and evolved adaptations causing contemporary epidemic of obesity as well as differences in dietary regimes and life-style between modern humans and their ancestors are described. Concerning eating disorders, a number of current evoluti...

  17. Evolutionary economics and regional policy

    Lambooy, Jan G.; Boschma, Ron

    2001-01-01

    The principal objective of this paper is to formulate some possible links between evolutionary economics and regional policy, a topic that has not (yet) been covered by the literature. We firstly give a brief overview of some issues of regional policy, conceived as a strategy to influence the spatial matrix of economic development. Then, we outline what we take to be the essential arguments and components of evolutionary economics. More in particular, we focus attention on the economic founda...

  18. Behaviour Trees for Evolutionary Robotics

    Scheper, Kirk Y. W.; Tijmons, Sjoerd; de Visser, Coen C.; de Croon, Guido C. H. E.

    2014-01-01

    Evolutionary Robotics allows robots with limited sensors and processing to tackle complex tasks by means of sensory-motor coordination. In this paper we show the first application of the Behaviour Tree framework to a real robotic platform using the Evolutionary Robotics methodology. This framework is used to improve the intelligibility of the emergent robotic behaviour as compared to the traditional Neural Network formulation. As a result, the behaviour is easier to comprehend and manually ad...

  19. Evolutionary computation for trading systems

    Kaucic, Massimiliano

    2008-01-01

    Evolutionary computations, also called evolutionary algorithms, consist of several heuristics, which are able to solve optimization tasks by imitating some aspects of natural evolution. They may use different levels of abstraction, but they are always working on populations of possible solutions for a given task. The basic idea is that if only those individuals of a population which meet a certain selection criteria reproduce, while the remaining individuals die, the population wi...

  20. Evolutionary Algorithms and Dynamic Programming

    Doerr, Benjamin; Eremeev, Anton; Neumann, Frank; Theile, Madeleine; Thyssen, Christian

    2013-01-01

    Recently, it has been proven that evolutionary algorithms produce good results for a wide range of combinatorial optimization problems. Some of the considered problems are tackled by evolutionary algorithms that use a representation which enables them to construct solutions in a dynamic programming fashion. We take a general approach and relate the construction of such algorithms to the development of algorithms using dynamic programming techniques. Thereby, we give general guidelines on how ...

  1. Evolutionary Algorithms in Astronautic Applications

    Maiwald, Volker

    2010-01-01

    Evolutionary algorithms (EA) are a computation tool that utilizes biological principles found in the evolution theory. One major difference to other optimization methods is the fact that a large group of solutions is evaluated, not a single one. Combination of various solutions from such a group, called population, allows improvement of the solutions. Overall several terms in usage in the field of evolutionary algorithms have their origin in genetics or biology, especially the ...

  2. Evolutionary Algorithms for Reinforcement Learning

    Grefenstette, J. J.; Moriarty, D. E.; Schultz, A.C.

    2011-01-01

    There are two distinct approaches to solving reinforcement learning problems, namely, searching in value function space and searching in policy space. Temporal difference methods and evolutionary algorithms are well-known examples of these approaches. Kaelbling, Littman and Moore recently provided an informative survey of temporal difference methods. This article focuses on the application of evolutionary algorithms to the reinforcement learning problem, emphasizing alternative policy represe...

  3. Estimation of precipitation rates by measurements of {sup 36}Cl in the GRIP ice core with the PSI/ETH tandem accelerator

    Wagner, G.; Baumgartner, S.; Beer, J. [EAWAG, Duebendorf (Switzerland); Synal, H.A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Suter, M. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Within the European Greenland ice core project (GRIP) {sup 36}Cl AMS measurements have been performed on ice core samples from Summit (Greenland, 73{sup o}N, 37{sup o}W). Most data analysed so far are from the lower part of the ice core. The {sup 36}Cl concentration is well correlated with {delta}{sup 18}O, which is considered as a proxy for paleotemperatures. Assuming that the deposition rate of radionuclides is independent of {delta}{sup 18}O, {sup 36}Cl is used to estimate the relationship between accumulation and {delta}{sup 18}O. The results confirm that the rapid changes of {delta}{sup 18}O, the so-called Dansgaard-Oeschger events, are also reflected in the precipitation rate. (author) 1 fig., 3 refs.

  4. Is strong hydrogen bonding in the transition state enough to account for the observed rate acceleration in a mutant of papain?

    Zheng, Ya-Jun; Bruice, Thomas C.

    1997-01-01

    Nitriles are good inhibitors for the cysteine protease papain. However, a single amino acid mutation (Gln-19 → Glu-19) in the active site makes the mutant enzyme a good catalyst for nitrile hydrolysis. A theoretical approach was used to examine the differential transition state stabilization in the papain mutant relative to the wild-type enzyme. Based on this study, we concluded that strong hydrogen bonding in the transition state is responsible for the observed rate enhancement of 4 × 105.

  5. Particle acceleration

    Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.; Alissandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.; Ellison, D.

    1986-01-01

    Data is compiled from Solar Maximum Mission and Hinothori satellites, particle detectors in several satellites, ground based instruments, and balloon flights in order to answer fundamental questions relating to: (1) the requirements for the coronal magnetic field structure in the vicinity of the energization source; (2) the height (above the photosphere) of the energization source; (3) the time of energization; (4) transistion between coronal heating and flares; (5) evidence for purely thermal, purely nonthermal and hybrid type flares; (6) the time characteristics of the energization source; (7) whether every flare accelerates protons; (8) the location of the interaction site of the ions and relativistic electrons; (9) the energy spectra for ions and relativistic electrons; (10) the relationship between particles at the Sun and interplanetary space; (11) evidence for more than one acceleration mechanism; (12) whether there is single mechanism that will accelerate particles to all energies and also heat the plasma; and (13) how fast the existing mechanisms accelerate electrons up to several MeV and ions to 1 GeV.

  6. Accelerator design

    The feasibility of constructing a TeV region electron-positron linear collider in Japan is discussed. The design target of the collider is given as follows: Energy, 1 TeV + 1 TeV; luminosity, 1032-1033/cm2/s; total length, 25km; electric power, 250MW; energy dispersion, 1%-10%; the start of the first experiment, early 1990s. For realizing the above target, the following research and developmental works are necessary. (a) Development of an acceleration tube with short filling time and high shunt resistance. (b) Short pulse microwave source with high peak power. (c) High current, single bunch linac. (d) Beam dynamics. As for the acceleration tube, some possibility is considered: For example, the use of DAW (Disk and Washer) which is being developed for TRISTAN as a traveling-wave tube; and the Jungle Gym-type acceleration tube. As a promising candidate for the microwave source, the Lasertron has been studied. The total cost of the collider construction is estimated to be about 310 billion yen, of which 120 billion yen is for the tunnel and buildings, and 190 billion yen for the accelerator facilities. The operation cost is estimated to be about 3 billion yen per month. (Aoki, K.)

  7. Accelerator operations

    This section is concerned with the operation of both the tandem-linac system and the Dynamitron, two accelerators that are used for entirely different research. Developmental activities associated with the tandem and the Dynamitron are also treated here, but developmental activities associated with the superconducting linac are covered separately because this work is a program of technology development in its own right

  8. Advanced accelerators

    This report discusses the suitability of four novel particle acceleration technologies for multi-TeV particle physics machines: laser driven linear accelerators (linac), plasma beat-wave devices, plasma wakefield devices, and switched power and cavity wakefield linacs. The report begins with the derivation of beam parameters practical for multi-TeV devices. Electromagnetic field breakdown of materials is reviewed. The two-beam accelerator scheme for using a free electron laser as the driver is discussed. The options recommended and the conclusions reached reflect the importance of cost. We recommend that more effort be invested in achieving a self-consistent range of TeV accelerator design parameters. Beat-wave devices have promise for 1-100 GeV applications and, while not directly scalable to TeV designs, the current generation of ideas are encouraging for the TeV regime. In particular, surfatrons, finite-angle optical mixing devices, plasma grating accelerator, and the Raman forward cascade schemes all deserve more complete analysis. The exploitation of standard linac geometry operated in an unconventional mode is in a phase of rapid evolution. While conceptual projects abound, there are no complete designs. We recommend that a fraction of sponsored research be devoted to this approach. Wakefield devices offer a great deal of potential; trades among their benefits and constraints are derived and discussed herein. The study of field limitation processes has received inadequate attention; this limits experiment designers. The costs of future experiments are such that investment in understanding these processes is prudent. 34 refs., 12 figs., 3 tabs

  9. Heritable symbiosis: The advantages and perils of an evolutionary rabbit hole.

    Bennett, Gordon M; Moran, Nancy A

    2015-08-18

    Many eukaryotes have obligate associations with microorganisms that are transmitted directly between generations. A model for heritable symbiosis is the association of aphids, a clade of sap-feeding insects, and Buchnera aphidicola, a gammaproteobacterium that colonized an aphid ancestor 150 million years ago and persists in almost all 5,000 aphid species. Symbiont acquisition enables evolutionary and ecological expansion; aphids are one of many insect groups that would not exist without heritable symbiosis. Receiving less attention are potential negative ramifications of symbiotic alliances. In the short run, symbionts impose metabolic costs. Over evolutionary time, hosts evolve dependence beyond the original benefits of the symbiosis. Symbiotic partners enter into an evolutionary spiral that leads to irreversible codependence and associated risks. Host adaptations to symbiosis (e.g., immune-system modification) may impose vulnerabilities. Symbiont genomes also continuously accumulate deleterious mutations, limiting their beneficial contributions and environmental tolerance. Finally, the fitness interests of obligate heritable symbionts are distinct from those of their hosts, leading to selfish tendencies. Thus, genes underlying the host-symbiont interface are predicted to follow a coevolutionary arms race, as observed for genes governing host-pathogen interactions. On the macroevolutionary scale, the rapid evolution of interacting symbiont and host genes is predicted to accelerate host speciation rates by generating genetic incompatibilities. However, degeneration of symbiont genomes may ultimately limit the ecological range of host species, potentially increasing extinction risk. Recent results for the aphid-Buchnera symbiosis and related systems illustrate that, whereas heritable symbiosis can expand ecological range and spur diversification, it also presents potential perils. PMID:25713367

  10. Effects of Different Methods of Accelerated Germination on Germination Rate of Pinus sylvestris var .mongolica%不同催芽方式对樟子松发芽率的影响

    杨丽清

    2015-01-01

    In order to grasp the effects of different methods of accelerated germination on germination rate of Pinus sylvestris var .mongolica seeds ,the germination experiments were conducted at room temperature .Result shows that the germination rate of Pinus sylvestris var .mongolica is not the same by using different methods of acceler‐ated germination;among of which the effect is optimal by soaking 200 mg ▌L -1 GA3 ,the germination rate being 60% ,followed by 40 ℃ warm water soaking ,the germination rate being 57% .%为了解不同催芽方式对樟子松种子发芽率的影响,在室温下进行了发芽试验。结果表明,不同催芽方式樟子松种子发芽率不相同,其中200mg▌L-1赤霉素溶液浸种效果最好,发芽率达到60%;其次为40℃温水浸种,发芽率达到57%。

  11. A High-Fat Diet Containing Lard Accelerates Prostate Cancer Progression and Reduces Survival Rate in Mice: Possible Contribution of Adipose Tissue-Derived Cytokines

    Han Jin Cho

    2015-04-01

    Full Text Available To examine the effects of high-fat diet (HFD containing lard on prostate cancer development and progression and its underlying mechanisms, transgenic adenocarcinoma mouse prostate (TRAMP and TRAMP-C2 allograft models, as well as in vitro culture models, were employed. In TRAMP mice, HFD feeding increased the incidence of poorly differentiated carcinoma and decreased that of prostatic intraepithelial neoplasia in the dorsolateral lobes of the prostate, which was accompanied by increased expression of proteins associated with proliferation and angiogenesis. HFD feeding also led to increased metastasis and decreased survival rate in TRAMP mice. In the allograft model, HFD increased solid tumor growth, the expression of proteins related to proliferation/angiogenesis, the number of lipid vacuoles in tumor tissues, and levels of several cytokines in serum and adipose tissue. In vitro results revealed that adipose tissue-conditioned media from HFD-fed mice stimulated the proliferation and migration of prostate cancer cells and angiogenesis compared to those from control-diet-fed mice. These results indicate that the increase of adipose tissue-derived soluble factors by HFD feeding plays a role in the growth and metastasis of prostate cancer via endocrine and paracrine mechanisms. These results provide evidence that a HFD containing lard increases prostate cancer development and progression, thereby reducing the survival rate.

  12. Dielectric laser accelerators

    England, R. Joel; Noble, Robert J.; Bane, Karl; Dowell, David H.; Ng, Cho-Kuen; Spencer, James E.; Tantawi, Sami; Wu, Ziran; Byer, Robert L.; Peralta, Edgar; Soong, Ken; Chang, Chia-Ming; Montazeri, Behnam; Wolf, Stephen J.; Cowan, Benjamin; Dawson, Jay; Gai, Wei; Hommelhoff, Peter; Huang, Yen-Chieh; Jing, Chunguang; McGuinness, Christopher; Palmer, Robert B.; Naranjo, Brian; Rosenzweig, James; Travish, Gil; Mizrahi, Amit; Schachter, Levi; Sears, Christopher; Werner, Gregory R.; Yoder, Rodney B.

    2014-10-01

    The use of infrared lasers to power optical-scale lithographically fabricated particle accelerators is a developing area of research that has garnered increasing interest in recent years. The physics and technology of this approach is reviewed, which is referred to as dielectric laser acceleration (DLA). In the DLA scheme operating at typical laser pulse lengths of 0.1 to 1 ps, the laser damage fluences for robust dielectric materials correspond to peak surface electric fields in the GV /m regime. The corresponding accelerating field enhancement represents a potential reduction in active length of the accelerator between 1 and 2 orders of magnitude. Power sources for DLA-based accelerators (lasers) are less costly than microwave sources (klystrons) for equivalent average power levels due to wider availability and private sector investment. Because of the high laser-to-particle coupling efficiency, required pulse energies are consistent with tabletop microJoule class lasers. Combined with the very high (MHz) repetition rates these lasers can provide, the DLA approach appears promising for a variety of applications, including future high-energy physics colliders, compact light sources, and portable medical scanners and radiative therapy machines.

  13. Stochastic modeling of Lagrangian accelerations

    Reynolds, Andy

    2002-11-01

    It is shown how Sawford's second-order Lagrangian stochastic model (Phys. Fluids A 3, 1577-1586, 1991) for fluid-particle accelerations can be combined with a model for the evolution of the dissipation rate (Pope and Chen, Phys. Fluids A 2, 1437-1449, 1990) to produce a Lagrangian stochastic model that is consistent with both the measured distribution of Lagrangian accelerations (La Porta et al., Nature 409, 1017-1019, 2001) and Kolmogorov's similarity theory. The later condition is found not to be satisfied when a constant dissipation rate is employed and consistency with prescribed acceleration statistics is enforced through fulfilment of a well-mixed condition.

  14. MUON ACCELERATION

    BERG,S.J.

    2003-11-18

    One of the major motivations driving recent interest in FFAGs is their use for the cost-effective acceleration of muons. This paper summarizes the progress in this area that was achieved leading up to and at the FFAG workshop at KEK from July 7-12, 2003. Much of the relevant background and references are also given here, to give a context to the progress we have made.

  15. KEKB accelerator

    KEKB, the B-Factory at High Energy Accelerator Research Organization (KEK) recently achieved the luminosity of 1 x 1034 cm-2s-1. This luminosity is two orders higher than the world's level at 1990 when the design of KEKB started. This unprecedented result was made possible by KEKB's innovative design and technology in three aspects - beam focusing optics, high current storage, and beam - beam interaction. Now KEKB is leading the luminosity frontier of the colliders in the world. (author)

  16. Accelerating networks

    Evolving out-of-equilibrium networks have been under intense scrutiny recently. In many real-world settings the number of links added per new node is not constant but depends on the time at which the node is introduced in the system. This simple idea gives rise to the concept of accelerating networks, for which we review an existing definition and-after finding it somewhat constrictive-offer a new definition. The new definition provided here views network acceleration as a time dependent property of a given system as opposed to being a property of the specific algorithm applied to grow the network. The definition also covers both unweighted and weighted networks. As time-stamped network data becomes increasingly available, the proposed measures may be easily applied to such empirical datasets. As a simple case study we apply the concepts to study the evolution of three different instances of Wikipedia, namely, those in English, German, and Japanese, and find that the networks undergo different acceleration regimes in their evolution

  17. The major synthetic evolutionary transitions

    Solé, Ricard

    2016-01-01

    Evolution is marked by well-defined events involving profound innovations that are known as ‘major evolutionary transitions'. They involve the integration of autonomous elements into a new, higher-level organization whereby the former isolated units interact in novel ways, losing their original autonomy. All major transitions, which include the origin of life, cells, multicellular systems, societies or language (among other examples), took place millions of years ago. Are these transitions unique, rare events? Have they instead universal traits that make them almost inevitable when the right pieces are in place? Are there general laws of evolutionary innovation? In order to approach this problem under a novel perspective, we argue that a parallel class of evolutionary transitions can be explored involving the use of artificial evolutionary experiments where alternative paths to innovation can be explored. These ‘synthetic’ transitions include, for example, the artificial evolution of multicellular systems or the emergence of language in evolved communicating robots. These alternative scenarios could help us to understand the underlying laws that predate the rise of major innovations and the possibility for general laws of evolved complexity. Several key examples and theoretical approaches are summarized and future challenges are outlined. This article is part of the themed issue ‘The major synthetic evolutionary transitions’. PMID:27431528

  18. Evolutionary genetics of maternal effects.

    Wolf, Jason B; Wade, Michael J

    2016-04-01

    Maternal genetic effects (MGEs), where genes expressed by mothers affect the phenotype of their offspring, are important sources of phenotypic diversity in a myriad of organisms. We use a single-locus model to examine how MGEs contribute patterns of heritable and nonheritable variation and influence evolutionary dynamics in randomly mating and inbreeding populations. We elucidate the influence of MGEs by examining the offspring genotype-phenotype relationship, which determines how MGEs affect evolutionary dynamics in response to selection on offspring phenotypes. This approach reveals important results that are not apparent from classic quantitative genetic treatments of MGEs. We show that additive and dominance MGEs make different contributions to evolutionary dynamics and patterns of variation, which are differentially affected by inbreeding. Dominance MGEs make the offspring genotype-phenotype relationship frequency dependent, resulting in the appearance of negative frequency-dependent selection, while additive MGEs contribute a component of parent-of-origin dependent variation. Inbreeding amplifies the contribution of MGEs to the additive genetic variance and, therefore enhances their evolutionary response. Considering evolutionary dynamics of allele frequency change on an adaptive landscape, we show that this landscape differs from the mean fitness surface, and therefore, under some condition, fitness peaks can exist but not be "available" to the evolving population. PMID:26969266

  19. Structural symmetry in evolutionary games.

    McAvoy, Alex; Hauert, Christoph

    2015-10-01

    In evolutionary game theory, an important measure of a mutant trait (strategy) is its ability to invade and take over an otherwise-monomorphic population. Typically, one quantifies the success of a mutant strategy via the probability that a randomly occurring mutant will fixate in the population. However, in a structured population, this fixation probability may depend on where the mutant arises. Moreover, the fixation probability is just one quantity by which one can measure the success of a mutant; fixation time, for instance, is another. We define a notion of homogeneity for evolutionary games that captures what it means for two single-mutant states, i.e. two configurations of a single mutant in an otherwise-monomorphic population, to be 'evolutionarily equivalent' in the sense that all measures of evolutionary success are the same for both configurations. Using asymmetric games, we argue that the term 'homogeneous' should apply to the evolutionary process as a whole rather than to just the population structure. For evolutionary matrix games in graph-structured populations, we give precise conditions under which the resulting process is homogeneous. Finally, we show that asymmetric matrix games can be reduced to symmetric games if the population structure possesses a sufficient degree of symmetry. PMID:26423436

  20. The major synthetic evolutionary transitions.

    Solé, Ricard

    2016-08-19

    Evolution is marked by well-defined events involving profound innovations that are known as 'major evolutionary transitions'. They involve the integration of autonomous elements into a new, higher-level organization whereby the former isolated units interact in novel ways, losing their original autonomy. All major transitions, which include the origin of life, cells, multicellular systems, societies or language (among other examples), took place millions of years ago. Are these transitions unique, rare events? Have they instead universal traits that make them almost inevitable when the right pieces are in place? Are there general laws of evolutionary innovation? In order to approach this problem under a novel perspective, we argue that a parallel class of evolutionary transitions can be explored involving the use of artificial evolutionary experiments where alternative paths to innovation can be explored. These 'synthetic' transitions include, for example, the artificial evolution of multicellular systems or the emergence of language in evolved communicating robots. These alternative scenarios could help us to understand the underlying laws that predate the rise of major innovations and the possibility for general laws of evolved complexity. Several key examples and theoretical approaches are summarized and future challenges are outlined.This article is part of the themed issue 'The major synthetic evolutionary transitions'. PMID:27431528

  1. Evolutionary biology and life histories

    Brown, C. R.

    2004-06-01

    Full Text Available The demographic processes that drive the spread of populations through environments and in turn determine the abundance of organisms are the same demographic processes that drive the spread of genes through populations and in turn determine gene frequencies and fitness. Conceptually, marked similarities exist in the dynamic processes underlying population ecology and those underlying evolutionary biology. Central to an understanding of both disciplines is life history and its component demographic rates, such as survival, fecundity, and age of first breeding, and biologists from both fields have a vested interest in good analytical machinery for the estimation and analysis of these demographic rates. In the EURING conferences, we have been striving since the mid 1980s to promote a quantitative understanding of demographic rates through interdisciplinary collaboration between ecologists and statisticians. From the ecological side, the principal impetus has come from population biology, and in particular from wildlife biology, but the importance of good quantitative insights into demographic processes has long been recognized by a number of evolutionary biologists (e.g., Nichols & Kendall, 1995; Clobert, 1995; Cooch et al., 2002. In organizing this session, we have aimed to create a forum for those committed to gaining the best possible understanding of evolutionary processes through the application of modern quantitative methods for the collection and interpretation of data on marked animal populations. Here we present a short overview of the material presented in the session on evolutionary biology and life histories. In a plenary talk, Brown & Brown (2004 explored how mark–recapture methods have allowed a better understanding of the evolution of group–living and alternative reproductive tactics in colonial cliff swallows (Petrochelidon pyrrhonota. By estimating the number of transient birds passing through colonies of different sizes, they

  2. Eco-evolutionary dynamics of dispersal in spatially heterogeneous environments.

    Hanski, Ilkka; Mononen, Tommi

    2011-10-01

    Ecology Letters (2011) 14: 1025-1034 ABSTRACT: Evolutionary changes in natural populations are often so fast that the evolutionary dynamics may influence ecological population dynamics and vice versa. Here we construct an eco-evolutionary model for dispersal by combining a stochastic patch occupancy metapopulation model with a model for changes in the frequency of fast-dispersing individuals in local populations. We test the model using data on allelic variation in the gene phosphoglucose isomerase (Pgi), which is strongly associated with dispersal rate in the Glanville fritillary butterfly. Population-specific measures of immigration and extinction rates and the frequency of fast-dispersing individuals among the immigrants explained 40% of spatial variation in Pgi allele frequency among 97 local populations. The model clarifies the roles of founder events and gene flow in dispersal evolution and resolves a controversy in the literature about the consequences of habitat loss and fragmentation on the evolution of dispersal. PMID:21794053

  3. IDEA: Interactive Display for Evolutionary Analyses

    Carlton Jane M

    2008-12-01

    Full Text Available Abstract Background The availability of complete genomic sequences for hundreds of organisms promises to make obtaining genome-wide estimates of substitution rates, selective constraints and other molecular evolution variables of interest an increasingly important approach to addressing broad evolutionary questions. Two of the programs most widely used for this purpose are codeml and baseml, parts of the PAML (Phylogenetic Analysis by Maximum Likelihood suite. A significant drawback of these programs is their lack of a graphical user interface, which can limit their user base and considerably reduce their efficiency. Results We have developed IDEA (Interactive Display for Evolutionary Analyses, an intuitive graphical input and output interface which interacts with PHYLIP for phylogeny reconstruction and with codeml and baseml for molecular evolution analyses. IDEA's graphical input and visualization interfaces eliminate the need to edit and parse text input and output files, reducing the likelihood of errors and improving processing time. Further, its interactive output display gives the user immediate access to results. Finally, IDEA can process data in parallel on a local machine or computing grid, allowing genome-wide analyses to be completed quickly. Conclusion IDEA provides a graphical user interface that allows the user to follow a codeml or baseml analysis from parameter input through to the exploration of results. Novel options streamline the analysis process, and post-analysis visualization of phylogenies, evolutionary rates and selective constraint along protein sequences simplifies the interpretation of results. The integration of these functions into a single tool eliminates the need for lengthy data handling and parsing, significantly expediting access to global patterns in the data.

  4. Seismic-induced accelerations detected by two parallel gravity meters in continuous recording with a high sampling rate at Etna volcano

    P. Stefanelli

    2008-06-01

    Full Text Available We analyse a microgravity data set acquired from two spring LaCoste & Romberg gravity meters operated in parallel at the same site on Etna volcano (Italy for about two months (August – September 2005. The high sampling rate acquisition (2Hz allowed the correlation of short-lasting gravity fluctuations with seismic events. After characterizing the oscillation behavior of the meters, through the study of spectral content and the background noise level of both sequences, we recognized fluctuations in the gravity data, spanning a range of periods from 1 second to about 30 seconds dominated by components with a period of about 15 ÷ 25 seconds, during time intervals encompassing both local seismic events and large worldwide earthquakes. The data analyses demonstrate that observed earthquake-induced gravity fluctuations have some differences due to diverse spectral content of the earthquakes. When local seismic events which present high frequency content excite the meters, the correlation between the two gravity signals is poor (factor < 0.3. Vice versa, when large worldwide earthquakes occur and low frequency seismic waves dominate the ensuing seismic wavefield, the resonance frequencies of the meters are excited and they react according to more common features. In the latter case, the signals from the two instruments are strongly correlated to each other (up to 0.9. In this paper the behaviors of spring gravimeters in the frequency range of the disturbances produced by local and large worldwide earthquakes are presented and discussed.

  5. Thermal characterization of Li/sulfur, Li/ S-LiFePO4 and Li/S-LiV3O8 cells using Isothermal Micro-Calorimetry and Accelerating Rate Calorimetry

    Seo, Jeongwook; Sankarasubramanian, Shrihari; Kim, Chi-Su; Hovington, Pierre; Prakash, Jai; Zaghib, Karim

    2015-09-01

    The thermal behavior of three cathode materials for the lithium/sulfur (Li/S) cell, namely - sulfur, sulfur-LiFePO4 (S-LFP) composite and sulfur-LiV3O8 (S-LVO) composite was studied using Isothermal Micro-Calorimetry (IMC) at various discharge rates. A continuum model was used to calculate the reversible entropic heat and irreversible resistive heat generated over the discharge process and the model data was compared to the experimental data to elucidate contributions of reversible and irreversible heats to the overall heat generated during discharge. The reaction enthalpy (ΔHRx) was measured using IMC for each elementary reaction step and in combination with the calculated reversible entropic heat and irreversible resistive heat was fitted against the experimental total heat measurement. The model showed an excellent fit against the experimental data. Further, Accelerating Rate Calorimetry (ARC) was used to study the thermal safety of these three cells. The cell with the S-LVO composite cathode was found to have the highest onset temperature for thermal runaway and also the lowest maximum self-heat rate. Results of this study suggest that S-LVO composite is a promising electrode for Li/S cells.

  6. Neuronal boost to evolutionary dynamics

    de Vladar, Harold P.; Szathmáry, Eörs

    2015-01-01

    Standard evolutionary dynamics is limited by the constraints of the genetic system. A central message of evolutionary neurodynamics is that evolutionary dynamics in the brain can happen in a neuronal niche in real time, despite the fact that neurons do not reproduce. We show that Hebbian learning and structural synaptic plasticity broaden the capacity for informational replication and guided variability provided a neuronally plausible mechanism of replication is in place. The synergy between learning and selection is more efficient than the equivalent search by mutation selection. We also consider asymmetric landscapes and show that the learning weights become correlated with the fitness gradient. That is, the neuronal complexes learn the local properties of the fitness landscape, resulting in the generation of variability directed towards the direction of fitness increase, as if mutations in a genetic pool were drawn such that they would increase reproductive success. Evolution might thus be more efficient within evolved brains than among organisms out in the wild. PMID:26640653

  7. On accelerated clocks and the quantum theory

    It is shown that the locality hypothesis of relativity breaks down for large proper accelerations which are relevant to semiclassical phenomena. A general modification for the rate of accelerated clocks incorporating the effect of proper acceleration is thus proposed. Connection is made with Caianiello's quantum line element

  8. Discovery and Optimization of Materials Using Evolutionary Approaches.

    Le, Tu C; Winkler, David A

    2016-05-25

    Materials science is undergoing a revolution, generating valuable new materials such as flexible solar panels, biomaterials and printable tissues, new catalysts, polymers, and porous materials with unprecedented properties. However, the number of potentially accessible materials is immense. Artificial evolutionary methods such as genetic algorithms, which explore large, complex search spaces very efficiently, can be applied to the identification and optimization of novel materials more rapidly than by physical experiments alone. Machine learning models can augment experimental measurements of materials fitness to accelerate identification of useful and novel materials in vast materials composition or property spaces. This review discusses the problems of large materials spaces, the types of evolutionary algorithms employed to identify or optimize materials, and how materials can be represented mathematically as genomes, describes fitness landscapes and mutation operators commonly employed in materials evolution, and provides a comprehensive summary of published research on the use of evolutionary methods to generate new catalysts, phosphors, and a range of other materials. The review identifies the potential for evolutionary methods to revolutionize a wide range of manufacturing, medical, and materials based industries. PMID:27171499

  9. Accelerators and the Accelerator Community

    Malamud, Ernest; Sessler, Andrew

    2008-06-01

    In this paper, standing back--looking from afar--and adopting a historical perspective, the field of accelerator science is examined. How it grew, what are the forces that made it what it is, where it is now, and what it is likely to be in the future are the subjects explored. Clearly, a great deal of personal opinion is invoked in this process.

  10. Evolutionary optimization of optical antennas

    Feichtner, Thorsten; Kiunke, Markus; Hecht, Bert

    2012-01-01

    The design of nano-antennas is so far mainly inspired by radio-frequency technology. However, material properties and experimental settings need to be reconsidered at optical frequencies, which entails the need for alternative optimal antenna designs. Here a checkerboard-type, initially random array of gold cubes is subjected to evolutionary optimization. To illustrate the power of the approach we demonstrate that by optimizing the near-field intensity enhancement the evolutionary algorithm finds a new antenna geometry, essentially a split-ring/two-wire antenna hybrid which surpasses by far the performance of a conventional gap antenna by shifting the n=1 split-ring resonance into the optical regime.

  11. The evolutionary psychology of hunger.

    Al-Shawaf, Laith

    2016-10-01

    An evolutionary psychological perspective suggests that emotions can be understood as coordinating mechanisms whose job is to regulate various psychological and physiological programs in the service of solving an adaptive problem. This paper suggests that it may also be fruitful to approach hunger from this coordinating mechanism perspective. To this end, I put forward an evolutionary task analysis of hunger, generating novel a priori hypotheses about the coordinating effects of hunger on psychological processes such as perception, attention, categorization, and memory. This approach appears empirically fruitful in that it yields a bounty of testable new hypotheses. PMID:27328100

  12. Diversity-Guided Evolutionary Algorithms

    Ursem, Rasmus Kjær

    2002-01-01

    Population diversity is undoubtably a key issue in the performance of evolutionary algorithms. A common hypothesis is that high diversity is important to avoid premature convergence and to escape local optima. Various diversity measures have been used to analyze algorithms, but so far few...... algorithms have used a measure to guide the search. The diversity-guided evolutionary algorithm (DGEA) uses the wellknown distance-to-average-point measure to alternate between phases of exploration (mutation) and phases of exploitation (recombination and selection). The DGEA showed remarkable results...

  13. accelerating cavity

    On the inside of the cavitytThere is a layer of niobium. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment.

  14. Instability in evolutionary games.

    Zimo Yang

    Full Text Available BACKGROUND: Phenomena of instability are widely observed in many dissimilar systems, with punctuated equilibrium in biological evolution and economic crises being noticeable examples. Recent studies suggested that such instabilities, quantified by the abrupt changes of the composition of individuals, could result within the framework of a collection of individuals interacting through the prisoner's dilemma and incorporating three mechanisms: (i imitation and mutation, (ii preferred selection on successful individuals, and (iii networking effects. METHODOLOGY/PRINCIPAL FINDINGS: We study the importance of each mechanism using simplified models. The models are studied numerically and analytically via rate equations and mean-field approximation. It is shown that imitation and mutation alone can lead to the instability on the number of cooperators, and preferred selection modifies the instability in an asymmetric way. The co-evolution of network topology and game dynamics is not necessary to the occurrence of instability and the network topology is found to have almost no impact on instability if new links are added in a global manner. The results are valid in both the contexts of the snowdrift game and prisoner's dilemma. CONCLUSIONS/SIGNIFICANCE: The imitation and mutation mechanism, which gives a heterogeneous rate of change in the system's composition, is the dominating reason of the instability on the number of cooperators. The effects of payoffs and network topology are relatively insignificant. Our work refines the understanding on the driving forces of system instability.

  15. Marriage: an evolutionary perspective.

    Weisfeld, Glenn E; Weisfeld, Carol C

    2002-12-01

    Marriage is universal, and pair bonding is found in other species too with highly dependent young. So marriage functions as a reproductive social arrangement that traditionally involved the extended family. The sexes are not identical in their biological contributions to children's survival, so they seek somewhat different attributes in a mate. Men seek a young, attractive, sexually faithful bride. Women seek a man who is older, taller, and (as in many other species) socially dominant. Both sexes prefer a kind, healthy, attractive, similar mate who is emotionally attached to them. A spouse who fails to maintain sufficiently high mate value is vulnerable to divorce. Infertility and sexual dissatisfaction predict divorce, as does death of a child, but the more children, the stabler the marriage. Cross-cultural data suggest that cruel or subdominant men (e.g., poor providers) and unfaithful women are prone to divorce. Marriages in which the wife dominates the husband in economic contributions, nonverbal behavior, and decision making tend to be less satisfying. In societies in which wives are economically independent of husbands, divorce rates are high. As women's economic power has risen with industrialization, divorce rates have climbed. Economic and fitness considerations also help explain cultural differences in polygyny, age at marriage, arranged marriage, concern with the bride's sexual chastity, and marriage ceremonies. Other factors also affect marital dynamics, such as state subsidies to families, the sex ratio, and influence of the couple's parents. PMID:12496735

  16. Micro Evolutionary Processes and Adaptation

    SHADMANOV; R; K; RUBAN; I; N; VOROPAEVA; N; L; SHADMANOVA; A; R

    2008-01-01

    It would be well to note that in the absence of clear data about the formation of adaptation systems,or mechanisms of their occurrence,all that is recognized is the realization of the micro evolutionary processes.There is no well-defined connection between information exchange and formation of

  17. Evolutionary dynamics of mammalian karyotypes

    Carlo Alberto Redi

    2012-12-01

    Full Text Available This special volume of Cytogenetic and Genome Research (edited by Roscoe Stanyon, University of Florence and Alexander Graphodatsky, Siberian division of the Russian Academy of Sciences is dedicated to the fascinating long search of the forces behind the evolutionary dynamics of mammalian karyotypes, revealed after the hypotonic miracle of the 1950s....

  18. Evolutionary studies of the Gnetales

    Hou, Chen

    2016-01-01

    The Gnetales consist of three distinct genera, Ephedra, Gnetum and Welwitschia with considerable divergence among them regarding morphological, ecological and molecular characters. A longstanding debate of the similarity between the Gnetales and angiosperms and the unresolved seed plant phylogeny intrigues plant scientists to further investigate the evolutionary history of the Gnetales. The presented projects deal with interdisciplinary questions on proteomics, chloroplast genomes, phylogenet...

  19. The Challange of Evolutionary Learning.

    Banathy, Bela H.

    Emerging educational needs in the interdependent world of the Information Age are explored. The current global human predicament in the historical context of the evolution of human systems is examined. A description is given of a systems view of the current evolutionary stage and the new educational needs of the Information Age that can be derived…

  20. Evolutionary Psychology and Intelligence Research

    Kanazawa, Satoshi

    2010-01-01

    This article seeks to unify two subfields of psychology that have hitherto stood separately: evolutionary psychology and intelligence research/differential psychology. I suggest that general intelligence may simultaneously be an evolved adaptation and an individual-difference variable. Tooby and Cosmides's (1990a) notion of random quantitative…

  1. Evolutionary Perspective in Child Growth

    Ze’ev Hochberg

    2011-07-01

    Full Text Available Hereditary, environmental, and stochastic factors determine a child’s growth in his unique environment, but their relative contribution to the phenotypic outcome and the extent of stochastic programming that is required to alter human phenotypes is not known because few data are available. This is an attempt to use evolutionary life-history theory in understanding child growth in a broad evolutionary perspective, using the data and theory of evolutionary predictive adaptive growth-related strategies. Transitions from one life-history phase to the next have inherent adaptive plasticity in their timing. Humans evolved to withstand energy crises by decreasing their body size, and evolutionary short-term adaptations to energy crises utilize a plasticity that modifies the timing of transition from infancy into childhood, culminating in short stature in times of energy crisis. Transition to juvenility is part of a strategy of conversion from a period of total dependence on the family and tribe for provision and security to self-supply, and a degree of adaptive plasticity is provided and determines body composition. Transition to adolescence entails plasticity in adapting to energy resources, other environmental cues, and the social needs of the maturing adolescent to determine life-span and the period of fecundity and fertility. Fundamental questions are raised by a life-history approach to the unique growth pattern of each child in his given genetic background and current environment.

  2. Electron Accelerator Facilities

    Lecture presents main aspects of progress in development of industrial accelerators: adaptation of accelerators primary built for scientific experiments, electron energy and beam power increase in certain accelerator constructions, computer control system managing accelerator start-up, routine operation and technological process, maintenance (diagnostics), accelerator technology perfection (electrical efficiency, operation cost), compact and more efficient accelerator constructions, reliability improvement according to industrial standards, accelerators for MW power levels and accelerators tailored for specific use

  3. Spatial distribution of air kerma rate and impact of accelerating voltage on the quality of an ultra soft X-ray beam generated by a cold cathode tube in air

    Ultrasoft X-ray characteristic aluminum K alpha line (Al Kα with energy of 1.5 keV) is used in radiobiological experiments to study the effect of radiation on biological matter. A simple method to generate a continuous beam of those X-ray radiations is to bombarding an aluminum target with accelerated electrons using high voltage (HV). In this work, by varying the HV we study the characteristics of a photon beam generated by means of a cold cathode transmission X-ray tube. The anode is a thin (16 μm) aluminum foil supported by a copper grid. The spatial distribution of air kerma is measured using gafchromic films of HD-810 calibrated with a parallel plate free-air ionization chamber. We show that HV strongly modifies the energetic spectrum and air kerma rate as well as its uniformity and intensity in air. - Highlights: • We measured energy spectrum of X-ray beam. • We calibrate the Gafchromic films to measure air kerma of X-ray beam. • Spatial air kerma rate is determined and interpreted. • We define dimensions and position of future biological sample irradiation using Al Kα X-ray

  4. Accelerator system and method of accelerating particles

    Wirz, Richard E. (Inventor)

    2010-01-01

    An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

  5. Evolutionary traps and range shifts in a rapidly changing world.

    Hale, Robin; Morrongiello, John R; Swearer, Stephen E

    2016-06-01

    Humans are altering the environment at an unprecedented rate. Although behavioural plasticity has allowed many species to respond by shifting their ranges to more favourable conditions, these rapid environmental changes may cause 'evolutionary traps', whereby animals mistakenly prefer resources that reduce their fitness. The role of evolutionary traps in influencing the fitness consequences of range shifts remains largely unexplored. Here, we review these interactions by considering how climate change may trigger maladaptive developmental pathways or increase the probability of animals encountering traps. We highlight how traps could selectively remove some phenotypes and compromise population persistence. We conclude by highlighting emerging areas of research that would improve our understanding of when interactions between evolutionary traps and range shifts are likely to be most detrimental to animals. PMID:27330167

  6. An Evolutionary Framework for 3-SAT Problems

    Borgulya, István

    2003-01-01

    In this paper we present a new evolutionary framework for 3-SAT. This method can be divided into three stages, where each stage is an evolutionary algorithm. The first stage improves the quality of the initial population. The second stage improves the speed of the algorithm periodically generating new solutions. The 3rd stage is a hybrid evolutionary algorithm, which improves the solutions with a local search. The key points of our algorithm are the evolutionary framework and the mutation ope...

  7. From computers to cultivation: reconceptualizing evolutionary psychology

    Louise eBarrett; Thomas ePollet; Gert eStulp

    2014-01-01

    Does evolutionary theorizing have a role in psychology? This is a more contentious issue than one might imagine, given that as evolved creatures, the answer must surely be yes. The contested nature of evolutionary psychology lies not in our status as evolved beings, but in the extent to which evolutionary ideas add value to studies of human behaviour, and the rigour with which these ideas are tested. This, in turn, is linked to the framework in which particular evolutionary ideas are situated...

  8. From computers to cultivation: reconceptualizing evolutionary psychology

    Barrett, Louise; Pollet, Thomas V.; Stulp, Gert

    2014-01-01

    Does evolutionary theorizing have a role in psychology? This is a more contentious issue than one might imagine, given that, as evolved creatures, the answer must surely be yes. The contested nature of evolutionary psychology lies not in our status as evolved beings, but in the extent to which evolutionary ideas add value to studies of human behavior, and the rigor with which these ideas are tested. This, in turn, is linked to the framework in which particular evolutionary ideas are situated....

  9. Evolutionary Optimization in an Algorithmic Setting

    Burgin, Mark; Eberbach, Eugene

    2006-01-01

    Evolutionary processes proved very useful for solving optimization problems. In this work, we build a formalization of the notion of cooperation and competition of multiple systems working toward a common optimization goal of the population using evolutionary computation techniques. It is justified that evolutionary algorithms are more expressive than conventional recursive algorithms. Three subclasses of evolutionary algorithms are proposed here: bounded finite, unbounded finite and infinite...

  10. OPTIMISED RANDOM MUTATIONS FOR EVOLUTIONARY ALGORITHMS

    Sean McGerty; Frank Moisiadis

    2014-01-01

    To demonstrate our approaches we will use Sudoku puzzles, which are an excellent test bed for evolutionary algorithms. The puzzles are accessible enough for people to enjoy. However the more complex puzzles require thousands of iterations before an evolutionary algorithm finds a solution. If we were attempting to compare evolutionary algorithms we could count their iterations to solution as an indicator of relative efficiency. Evolutionary algorithms however include a process of r...

  11. Analyzing Nonstationary Random Response of a SDOF System under the Evolutionary Random Excitation by Wavelet Transform

    LI Fang-bing; ZHANG Tian-shu

    2006-01-01

    For evolutionary random excitations, a general method of analyzing nonstationary random responses of systems was presented in this paper. Firstly, for the evolutionary random excitation model, the evolutionary power spectrum density function (EPSD) of a random excitation was given by wavelet transform. Based on the EPSD, the nonstationary responses of a SDOF system subjected to evolutionary random excitations were studied. The application and validity of presented method were illustrated by numerical examples. In numerical examples, the recently developed stochastic models for EI Contro (1934) and Mexico City (1985) earthquakes which preserve the nonstationary evolutions of amplitude and frequency content of ground accelerations were used as excitations. The nonstationary random mean-square responses of a SDOF system under these two excitations were evaluated and compared with simulated results.

  12. Accelerated GLAS exposure station

    The Geoscience Laser Altimeter System (GLAS) is being developed by NASA/GSFC to measure the dynamics of the ice sheet mass balance, land, and cloud and atmospheric properties. An instrument altimetric resolution of 10 cm per shot is required. The laser transmitter will be a diode pumped, Q-switched, Nd:YAG laser producing 1064 nm, 100 mJ, 4 ns pulses at 40 Hz repetition rate in a TEM∞ mode. A minimum lifetime goal of 2 billion shots is required per laser transmitter. The performance of the GLAS laser can be limited by physical damage to the optical components caused by the interaction of intense laser energy with the optical coatings and substrates. Very little data exists describing the effects of long duration laser exposure, of 4 ns pulses, on an optical component. An Accelerated GLAS Exposure Station (AGES) is being developed which will autonomously operate and monitor the GLAS laser at an accelerated rate of 500 Hz. The effects of a large number of laser shots will be recorded. Parameters to be monitored include: laser power, pulsewidth, beam size, laser diode drive current and power, Q-switch drive voltage, temperature, and humidity. For comparison, one set of AGES-sister optical components will be used in the non-accelerated GLAS laser and another will be evaluated by a commercial optical damage test facility

  13. The citation field of evolutionary economics

    Dolfsma, Wilfred; Leydesdorff, Loet

    2010-01-01

    Evolutionary economics has developed into an academic field of its own, institutionalized around, amongst others, the Journal of Evolutionary Economics (JEE). This paper analyzes the way and extent to which evolutionary economics has become an interdisciplinary journal, as its aim was: a journal tha

  14. On the Analysis of Evolutionary Algorithms

    Jansen, Thomas; Wegener, Ingo

    2001-01-01

    There is a lot of experimental evidence that crossover is, for some functions, an essential operator of evolutionary algorithms. Nevertheless, it was an open problem to prove for some function that an evolutionary algorithm using crossover is essentially more efficient than evolutionary algorithms without crossover. In this paper, such an example is presented and its properties are proved.

  15. Advanced medical accelerator design

    This report describes the design of an advanced medical facility dedicated to charged particle radiotherapy and other biomedical applications of relativistic heavy ions. Project status is reviewed and some technical aspects discussed. Clinical standards of reliability are regarded as essential features of this facility. Particular emphasis is therefore placed on the control system and on the use of technology which will maximize operational efficiency. The accelerator will produce a variety of heavy ion beams from helium to argon with intensities sufficient to provide delivered dose rates of several hundred rad/minute over large, uniform fields. The technical components consist of a linac injector with multiple PIG ion sources, a synchrotron and a versatile beam delivery system. An overview is given of both design philosophy and selected accelerator subsystems. Finally, a plan of the facility is described

  16. Schroedinger operators and evolutionary strategies

    First we introduce a simple model for the description of evolutionary algorithms, which is based on 2nd order partial differential equations for the distribution function of the individuals. Then we turn to the properties of Boltzmann's and Darwin's strategy. the next chapter is dedicated to the mathematical properties of Schroedinger operators. Both statements on the spectral density and their reproducibility during the simulation are summarized. The remaining of this chapter are dedicated to the analysis of the kernel as well as the dependence of the Schroedinger operator on the potential. As conclusion from the results of this chapter we obtain the classification of the strategies in dependence of the fitness. We obtain the classification of the evolutionary strategies, which are described by a 2nd order partial differential equation, in relation to their solution behaviour. Thereafter we are employed with the variation of the mutation distribution

  17. Evolutionary model of stock markets

    Kaldasch, Joachim

    2014-12-01

    The paper presents an evolutionary economic model for the price evolution of stocks. Treating a stock market as a self-organized system governed by a fast purchase process and slow variations of demand and supply the model suggests that the short term price distribution has the form a logistic (Laplace) distribution. The long term return can be described by Laplace-Gaussian mixture distributions. The long term mean price evolution is governed by a Walrus equation, which can be transformed into a replicator equation. This allows quantifying the evolutionary price competition between stocks. The theory suggests that stock prices scaled by the price over all stocks can be used to investigate long-term trends in a Fisher-Pry plot. The price competition that follows from the model is illustrated by examining the empirical long-term price trends of two stocks.

  18. The evolutionary origins of hierarchy

    Mengistu, Henok; Huizinga, Joost; Mouret, Jean-Baptiste; Clune, Jeff

    2015-01-01

    Hierarchical organization -- the recursive composition of sub-modules -- is ubiquitous in biological networks, including neural, metabolic, ecological, and genetic regulatory networks, and in human-made systems, such as large organizations and the Internet. To date, most research on hierarchy in networks has been limited to quantifying this property. However, an open, important question in evolutionary biology is why hierarchical organization evolves in the first place. It has recently been s...

  19. Lesbian tomboys and "evolutionary butch".

    Zevy, Lee

    2004-01-01

    ABSTRACT Lesbian tomboy development occurs within a psychosexual experiential field on a continuum from childhood gender dissonance to evolutionary butch in adulthood. Through the process of integrating gender development, sexual orientation, and identity development, tomboy lesbians learn how to maintain a sense of self and organize desire within a complicated familial/socio/cultural/context. Traversing these complications usually brings adolescent and adult lesbians into therapy where they need clinicians who understand this unique course of development. PMID:24820882

  20. Evolutionary Bits'n'Spikes

    D. Floreano; Schoeni, N.; Caprari, G.; Blynel, J.; Standish, R. K.; Beadau, M. A.; Abbass, H. A.

    2002-01-01

    We describe a model and implementation of evolutionary spiking neurons for embedded microcontrollers with few bytes of memory and very low power consumption. The approach is tested with an autonomous microrobot of less than 1 in^3 that evolves the ability to move in a small maze without human intervention and external computers. Considering the very large diffusion, small size, and low cost of embedded microcontrollers, the approach described here could find its way in several intelligent dev...

  1. Evolutionary potential games on lattices

    Szabo, Gyorgy; Borsos, Istvan

    2015-01-01

    Game theory provides a general mathematical background to study the effect of pair interactions and evolutionary rules on the macroscopic behavior of multi-player games where players with a finite number of strategies may represent a wide scale of biological objects, human individuals, or even their associations. In these systems the interactions are characterized by matrices that can be decomposed into elementary matrices (games) and classified into four types. The concept of decomposition h...

  2. Mutualism, Parasitism, and Evolutionary Adaptation

    Watson, Richard A.; Reil, Torsten; Pollack, Jordan B.

    2000-01-01

    Our investigations concern the role of symbiosis as an enabling mechanism in evolutionary adaptation. Previous work has illustrated how the formation of mutualist groups can guide genetic variation so as to enable the evolution of ultimately independent organisms that would otherwise be unobtainable. The new experiments reported here show that this effect applies not just in genetically related organisms but may also occur from symbiosis between distinct species. In addition, a new detail is ...

  3. Evolutionary robotics – A review

    Dilip Kumar Pratihar

    2003-12-01

    In evolutionary robotics, a suitable robot control system is developed automatically through evolution due to the interactions between the robot and its environment. It is a complicated task, as the robot and the environment constitute a highly dynamical system. Several methods have been tried by various investigators to solve this problem. This paper provides a survey on some of these important studies carried out in the recent past.

  4. Evolutionary biology and life histories

    Brown, C R; Thomson, D. L.

    2004-01-01

    The demographic processes that drive the spread of populations through environments and in turn determine the abundance of organisms are the same demographic processes that drive the spread of genes through populations and in turn determine gene frequencies and fitness. Conceptually, marked similarities exist in the dynamic processes underlying population ecology and those underlying evolutionary biology. Central to an understanding of both disciplines is life history and its component demogr...

  5. On evolutionary spatial heterogeneous games

    Fort, H.

    2008-03-01

    How cooperation between self-interested individuals evolve is a crucial problem, both in biology and in social sciences, that is far from being well understood. Evolutionary game theory is a useful approach to this issue. The simplest model to take into account the spatial dimension in evolutionary games is in terms of cellular automata with just a one-parameter payoff matrix. Here, the effects of spatial heterogeneities of the environment and/or asymmetries in the interactions among the individuals are analysed through different extensions of this model. Instead of using the same universal payoff matrix, bimatrix games in which each cell at site ( i, j) has its own different ‘temptation to defect’ parameter T(i,j) are considered. First, the case in which these individual payoffs are constant in time is studied. Second, an evolving evolutionary spatial game such that T=T(i,j;t), i.e. besides depending on the position evolves (by natural selection), is used to explore the combination of spatial heterogeneity and natural selection of payoff matrices.

  6. Testing evolutionary convergence on Europa

    A major objective in solar system exploration is the insertion of appropriate biology-oriented experiments in future missions. We discuss various reasons for suggesting that this type of research be considered a high priority for feasibility studies and, subsequently, for technological development of appropriate melters and submersibles. Based on numerous examples, we argue in favour of the assumption that Darwin's theory is valid for the evolution of life anywhere in the universe. We have suggested how to obtain preliminary insights into the question of the distribution of life in the universe. Universal evolution of intelligent behaviour is at the end of an evolutionary pathway, in which evolution of ion channels in the membrane of microorganisms occurs in its early stages. Further, we have argued that a preliminary test of this conjecture is feasible with experiments on the Europan surface or ocean, involving evolutionary biosignatures (ion channels). This aspect of the exploration for life in the solar system should be viewed as a complement to the astronomical approach for the search of evidence of the later stages of the evolutionary pathways towards intelligent behaviour. (author)

  7. DOE-HEP Final Report for 2013-2016: Studies of plasma wakefields for high repetition-rate plasma collider, and Theoretical study of laser-plasma proton and ion acceleration

    Katsouleas, Thomas C. [Duke Univ., Durham, NC (United States). Dept. of Electrical and Computer Engineering; Sahai, Aakash A. [Imperial College, London (United Kingdom). Dept. of Physics

    2016-08-08

    There were two goals for this funded project: 1. Studies of plasma wakefields for high repetition-rate plasma collider, and 2. Theoretical study of laser-plasma proton and ion acceleration. For goal 1, an analytical model was developed to determine the ion-motion resulting from the interaction of non-linear “blow-out” wakefields excited by beam-plasma and laser-plasma interactions. This is key to understanding the state of the plasma at timescales of 1 picosecond to a few 10s of picoseconds behind the driver-energy pulse. More information can be found in the document. For goal 2, we analytically and computationally analyzed the longitudinal instabilities of the laser-plasma interactions at the critical layer. Specifically, the process of “Doppler-shifted Ponderomotive bunching” is significant to eliminate the very high-energy spread and understand the importance of chirping the laser pulse frequency. We intend to publish the results of the mixing process in 2-D. We intend to publish Chirp-induced transparency. More information can be found in the document.

  8. An Evolutionary Perspective on the Crabtree Effect

    Thomas ePfeiffer

    2014-10-01

    Full Text Available The capability to ferment sugars into ethanol is a key metabolic trait of yeasts. Crabtree-positive yeasts use fermentation even in the presence of oxygen, where they could, in principle, rely on the respiration pathway. This is surprising because fermentation has a much lower ATP yield than respiration (2 ATP vs. approximately 18 ATP per glucose. While genetic events in the evolution of the Crabtree effect have been identified, the selective advantages provided by this trait remain controversial. In this review we analyse explanations for the emergence of the Crabtree effect from an evolutionary and game-theoretical perspective. We argue that an increased rate of ATP production is likely the most important factor behind the emergence of the Crabtree effect.

  9. Human mortality improvement in evolutionary context

    Burger, Oskar; Baudisch, Annette; Vaupel, James W

    2012-01-01

    human mortality has decreased so substantially that the difference between hunter-gatherers and today's lowest mortality populations is greater than the difference between hunter-gatherers and wild chimpanzees. The bulk of this mortality reduction has occurred since 1900 and has been experienced by only......Life expectancy is increasing in most countries and has exceeded 80 in several, as low-mortality nations continue to make progress in averting deaths. The health and economic implications of mortality reduction have been given substantial attention, but the observed malleability of human mortality...... has not been placed in a broad evolutionary context. We quantify the rate and amount of mortality reduction by comparing a variety of human populations to the evolved human mortality profile, here estimated as the average mortality pattern for ethnographically observed hunter-gatherers. We show that...

  10. Objective and Longitudinal Assessment of Dermatitis After Postoperative Accelerated Partial Breast Irradiation Using High-Dose-Rate Interstitial Brachytherapy in Patients With Breast Cancer Treated With Breast Conserving Therapy: Reduction of Moisture Deterioration by APBI

    Tanaka, Eiichi [Department of Radiation Oncology, National Hospital Organization, Osaka National Hospital, Osaka (Japan); Yamazaki, Hideya, E-mail: hideya10@hotmail.com [Department of Radiology, Kyoto Prefectural University of Medicine, Kyoto (Japan); Yoshida, Ken; Takenaka, Tadashi [Department of Radiation Oncology, National Hospital Organization, Osaka National Hospital, Osaka (Japan); Masuda, Norikazu [Department of Surgery and Breast Oncology, National Hospital Organization, Osaka National Hospital, Osaka (Japan); Kotsuma, Tadayuki; Yoshioka, Yasuo; Inoue, Takehiro [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita (Japan)

    2011-11-15

    Purpose: To objectively evaluate the radiation dermatitis caused by accelerated partial breast irradiation (APBI) using high-dose-rate interstitial brachytherapy. Patients and Methods: The skin color and moisture changes were examined using a newly installed spectrophotometer and corneometer in 22 patients who had undergone APBI using open cavity implant high-dose-rate interstitial brachytherapy (36 Gy in six fractions) and compared with the corresponding values for 44 patients in an external beam radiotherapy (EBRT) control group (50-60 Gy in 25-30 fractions within 5-6 weeks) after breast conserving surgery. Results: All values changed significantly as a result of APBI. The extent of elevation in a Asterisk-Operator (reddish) and reduction in L Asterisk-Operator (black) values caused by APBI were similar to those for EBRT, with slightly delayed recovery for 6-12 months after treatment owing to the surgical procedure. In contrast, only APBI caused a change in the b Asterisk-Operator values, and EBRT did not, demonstrating that the reduction in b Asterisk-Operator values (yellowish) depends largely on the surgical procedure. The changes in moisture were less severe after APBI than after EBRT, and the recovery was more rapid. The toxicity assessment using the Common Toxicity Criteria, version 3, showed that all dermatitis caused by APBI was Grade 2 or less. Conclusion: An objective analysis can quantify the effects of APBI procedures on color and moisture cosmesis. The radiation dermatitis caused by APBI using the present schedule showed an equivalent effect on skin color and a less severe effect on moisture than the effects caused by standard EBRT.

  11. Objective and Longitudinal Assessment of Dermatitis After Postoperative Accelerated Partial Breast Irradiation Using High-Dose-Rate Interstitial Brachytherapy in Patients With Breast Cancer Treated With Breast Conserving Therapy: Reduction of Moisture Deterioration by APBI

    Purpose: To objectively evaluate the radiation dermatitis caused by accelerated partial breast irradiation (APBI) using high-dose-rate interstitial brachytherapy. Patients and Methods: The skin color and moisture changes were examined using a newly installed spectrophotometer and corneometer in 22 patients who had undergone APBI using open cavity implant high-dose-rate interstitial brachytherapy (36 Gy in six fractions) and compared with the corresponding values for 44 patients in an external beam radiotherapy (EBRT) control group (50–60 Gy in 25–30 fractions within 5–6 weeks) after breast conserving surgery. Results: All values changed significantly as a result of APBI. The extent of elevation in a∗ (reddish) and reduction in L∗ (black) values caused by APBI were similar to those for EBRT, with slightly delayed recovery for 6–12 months after treatment owing to the surgical procedure. In contrast, only APBI caused a change in the b∗ values, and EBRT did not, demonstrating that the reduction in b∗ values (yellowish) depends largely on the surgical procedure. The changes in moisture were less severe after APBI than after EBRT, and the recovery was more rapid. The toxicity assessment using the Common Toxicity Criteria, version 3, showed that all dermatitis caused by APBI was Grade 2 or less. Conclusion: An objective analysis can quantify the effects of APBI procedures on color and moisture cosmesis. The radiation dermatitis caused by APBI using the present schedule showed an equivalent effect on skin color and a less severe effect on moisture than the effects caused by standard EBRT.

  12. Application of electron accelerator worldwide

    Electron accelerator is an important radiation source for radiation technology, which covers broad fields such as industry, health care, food and environmental protection. There are about 1,000 electron accelerators for radiation processing worldwide. Electron accelerator has advantage over Co-60 irradiator in term of high dose rate and power, assurance of safety, and higher economic performance at larger volume of irradiation. Accelerator generating higher energy in the range of 10 MeV and high power electron beam is now commercially available. There is a trend to use high-energy electron accelerator replacing Co-60 in case of large through-put of medical products. Irradiated foods, in particular species, are on the commercial market in 35 countries. Electron accelerator is used efficiently and economically for production of new or modified polymeric materials through radiation-induced cross-linking, grafting and polymerization reaction. Another important application of electron beam is the curing of surface coatings in the manufacture of products. Electron accelerators of large capacity are used for cleaning exhaust gases in industrial scale. Economic feasibility studies of this electron beam process have shown that this technology is more cost effective than the conventional process. It should be noted that the conventional limestone process produce gypsum as a by-product, which cannot be used in some countries. By contrast, the by-product of the electron beam process is a valuable fertilizer. (Y. Tanaka)

  13. PROTON ACCELERATION AT OBLIQUE SHOCKS

    Acceleration at the shock waves propagating oblique to the magnetic field is studied using a recently developed theoretical/numerical model. The model assumes that resonant hydromagnetic wave-particle interaction is the most important physical mechanism relevant to motion and acceleration of particles as well as to excitation and damping of waves. The treatment of plasma and waves is self-consistent and time dependent. The model uses conservation laws and resonance conditions to find where waves will be generated or damped, and hence particles will be pitch-angle-scattered. The total distribution is included in the model and neither introduction of separate population of seed particles nor some ad hoc escape rate of accelerated particles is needed. Results of the study show agreement with diffusive shock acceleration models in the prediction of power spectra for accelerated particles in the upstream region. However, they also reveal the presence of spectral break in the high-energy part of the spectra. The role of the second-order Fermi-like acceleration at the initial stage of the acceleration is discussed. The test case used in the paper is based on ISEE-3 data collected for the shock of 1978 November 12.

  14. Proton Acceleration at Oblique Shocks

    Galinsky, V. L.; Shevchenko, V. I.

    2011-06-01

    Acceleration at the shock waves propagating oblique to the magnetic field is studied using a recently developed theoretical/numerical model. The model assumes that resonant hydromagnetic wave-particle interaction is the most important physical mechanism relevant to motion and acceleration of particles as well as to excitation and damping of waves. The treatment of plasma and waves is self-consistent and time dependent. The model uses conservation laws and resonance conditions to find where waves will be generated or damped, and hence particles will be pitch-angle-scattered. The total distribution is included in the model and neither introduction of separate population of seed particles nor some ad hoc escape rate of accelerated particles is needed. Results of the study show agreement with diffusive shock acceleration models in the prediction of power spectra for accelerated particles in the upstream region. However, they also reveal the presence of spectral break in the high-energy part of the spectra. The role of the second-order Fermi-like acceleration at the initial stage of the acceleration is discussed. The test case used in the paper is based on ISEE-3 data collected for the shock of 1978 November 12.

  15. Top predators induce the evolutionary diversification of intermediate predator species.

    Zu, Jian; Yuan, Bo; Du, Jianqiang

    2015-12-21

    We analyze the evolutionary branching phenomenon of intermediate predator species in a tritrophic food chain model by using adaptive dynamics theory. Specifically, we consider the adaptive diversification of an intermediate predator species that feeds on a prey species and is fed upon by a top predator species. We assume that the intermediate predator׳s ability to forage on the prey can adaptively improve, but this comes at the cost of decreased defense ability against the top predator. First, we identify the general properties of trade-off relationships that lead to a continuously stable strategy or to evolutionary branching in the intermediate predator species. We find that if there is an accelerating cost near the singular strategy, then that strategy is continuously stable. In contrast, if there is a mildly decelerating cost near the singular strategy, then that strategy may be an evolutionary branching point. Second, we find that after branching has occurred, depending on the specific shape and strength of the trade-off relationship, the intermediate predator species may reach an evolutionarily stable dimorphism or one of the two resultant predator lineages goes extinct. PMID:26431773

  16. 3D RNA and Functional Interactions from Evolutionary Couplings.

    Weinreb, Caleb; Riesselman, Adam J; Ingraham, John B; Gross, Torsten; Sander, Chris; Marks, Debora S

    2016-05-01

    Non-coding RNAs are ubiquitous, but the discovery of new RNA gene sequences far outpaces the research on the structure and functional interactions of these RNA gene sequences. We mine the evolutionary sequence record to derive precise information about the function and structure of RNAs and RNA-protein complexes. As in protein structure prediction, we use maximum entropy global probability models of sequence co-variation to infer evolutionarily constrained nucleotide-nucleotide interactions within RNA molecules and nucleotide-amino acid interactions in RNA-protein complexes. The predicted contacts allow all-atom blinded 3D structure prediction at good accuracy for several known RNA structures and RNA-protein complexes. For unknown structures, we predict contacts in 160 non-coding RNA families. Beyond 3D structure prediction, evolutionary couplings help identify important functional interactions-e.g., at switch points in riboswitches and at a complex nucleation site in HIV. Aided by increasing sequence accumulation, evolutionary coupling analysis can accelerate the discovery of functional interactions and 3D structures involving RNA. PMID:27087444

  17. Pulsed DC accelerator for laser wakefield accelerator

    For the acceleration of ultra-short, high-brightness electron bunches, a pulsed DC accelerator was constructed. The pulser produced megavolt pulses of 1 ns duration in a vacuum diode. Results are presented from field emission of electrons in the diode. The results indicate that the accelerating gradient in the diode is approximately 1.5 GV/m

  18. Extinction Events Can Accelerate Evolution

    Lehman, Joel; Miikkulainen, Risto

    2015-01-01

    Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate...... evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending...... computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific in the...

  19. Linear Accelerator (LINAC)

    ... News Physician Resources Professions Site Index A-Z Linear Accelerator A linear accelerator (LINAC) customizes high energy x-rays to ... ensured? What is this equipment used for? A linear accelerator (LINAC) is the device most commonly used ...

  20. Terahertz-driven linear electron acceleration

    Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.

    2015-10-01

    The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30-50 MeV m-1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. These ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.

  1. Evolutionary Origin of the Proepicardium

    Elena Cano

    2013-05-01

    Full Text Available The embryonic epicardium and the cardiac mesenchyme derived from it are critical to heart development. The embryonic epicardium arises from an extracardiac progenitor tissue called the proepicardium, a proliferation of coelomic cells located at the limit between the liver and the sinus venosus. A proepicardium has not been described in invertebrates, and the evolutionary origin of this structure in vertebrates is unknown. We herein suggest that the proepicardium might be regarded as an evolutionary derivative from an ancient pronephric external glomerulus that has lost its excretory role. In fact, we previously described that the epicardium arises by cell migration from the primordia of the right pronephric external glomerulus in a representative of the most primitive vertebrate lineage, the lamprey Petromyzon marinus. In this review, we emphasize the striking similarities between the gene expression profiles of the proepicardium and the developing kidneys, as well as the parallelisms in the signaling mechanisms involved in both cases. We show some preliminary evidence about the existence of an inhibitory mechanism blocking glomerular differentiation in the proepicardium. We speculate as to the possibility that this developmental link between heart and kidney can be revealing a phylogenetically deeper association, supported by the existence of a heart-kidney complex in Hemichordates. Finally, we suggest that primitive hematopoiesis could be related with this heart-kidney complex, thus accounting for the current anatomical association of the hematopoietic stem cells with an aorta-gonad-mesonephros area. In summary, we think that our hypothesis can provide new perspectives on the evolutionary origin of the vertebrate heart.

  2. Steps Towards an Evolutionary Physics

    Tiezzi, E

    2006-01-01

    If thermodynamics is to physics as logic is to philosophy, recent theoretical advancements lend new coherence to the marvel and dynamism of life on Earth. Enzo Tiezzi's "Steps Towards an Evolutionary Physics" is a primer and guide, to those who would to stand on the shoulders of giants to attain this view: Heisenberg, Planck, Bateson, Varela, and Prigogine as well as notable contemporary scientists. The adventure of such a free and enquiring spirit thrives not so much on answers as on new questions. The book offers a new gestalt on the uncertainty principle and concept of probability. A wide r

  3. Evolutionary Optimization The UGP Toolkit

    Sanchez, Ernesto; Squillero, Giovanni

    2011-01-01

    This book describes an award-winning evolutionary algorithm that outperformed experts and conventional heuristics in solving several industrial problems. It presents a discussion of the theoretical and practical aspects that enabled I GP (MicroGP) to autonomously find the optimal solution of hard problems, handling highly structured data, such as full-fledged assembly programs, with functions and interrupt handlers. For a practitioner, I GP is simply a versatile optimizer to tackle most problems with limited setup effort. The book is valuable for all who require heuristic problem-solving metho

  4. Micro Evolutionary Processes and Adaptation

    SHADMANOV R K; RUBAN I N; VOROPAEVA N L; SHADMANOVA A R

    2008-01-01

    @@ It would be well to note that in the absence of clear data about the formation of adaptation systems,or mechanisms of their occurrence,all that is recognized is the realization of the micro evolutionary processes.There is no well-defined connection between information exchange and formation of adaptation systems.Obviously,it occurs because mechanisms and systems reacting to any external actions are not considered from the point of view of "coexistence" of dynamic and static processes and structures.

  5. Evolutionary robotics: model or design?

    Trianni, Vito

    2014-01-01

    In this paper, I review recent work in evolutionary robotics (ER), and discuss the perspectives and future directions of the field. First, I propose to draw a crisp distinction between studies that exploit ER as a design methodology on the one hand, and studies that instead use ER as a modeling tool to better understand phenomena observed in biology. Such a distinction is not always that obvious in the literature, however. It is my conviction that ER would profit from an explicit commitment t...

  6. Multidimensional extended spatial evolutionary games.

    Krześlak, Michał; Świerniak, Andrzej

    2016-02-01

    The goal of this paper is to study the classical hawk-dove model using mixed spatial evolutionary games (MSEG). In these games, played on a lattice, an additional spatial layer is introduced for dependence on more complex parameters and simulation of changes in the environment. Furthermore, diverse polymorphic equilibrium points dependent on cell reproduction, model parameters, and their simulation are discussed. Our analysis demonstrates the sensitivity properties of MSEGs and possibilities for further development. We discuss applications of MSEGs, particularly algorithms for modelling cell interactions during the development of tumours. PMID:26318169

  7. Improving DNA Computing Using Evolutionary Techniques

    Godar J. Ibrahim

    2016-03-01

    Full Text Available the field of DNA Computing has attracted many biologists and computer scientists as it has a biological interface, small size and substantial parallelism. DNA computing depends on DNA molecules’ biochemical reactions which they can randomly anneal and they might accidentally cause improper or unattractive computations. This will inspire opportunities to use evolutionary computation via DNA. Evolutionary Computation emphasizes on probabilistic search and optimization methods which are mimicking the organic evolution models. The research work aims at offering a simulated evolutionary DNA computing model which incorporates DNA computing with an evolutionary algorithm. This evolutionary approach provides the likelihood for increasing dimensionality through replacing the typical filtering method by an evolutionary one. Thus, via iteratively increasing and recombination a population of strands, eliminating incorrect solutions from the population, and choosing the best solutions via gel electrophoresis, an optimal or near-optimal solution can be evolved rather than extracted from the initial population.

  8. The emerging empirics of evolutionary economic geography

    Boschma, RA; Frenken, K Koen

    2010-01-01

    Following last decade’s programmatic papers on Evolutionary Economic Geography, we report on recent empirical advances and how this empirical work can be positioned vis-à-vis other strands of research in economic geography. First, we review studies on the path dependent nature of clustering, and how the evolutionary perspective relates to that of New Economic Geography. Second, we discuss research on agglomeration externalities in Regional Science, and how Evolutionary Economic Geography cont...

  9. EVOLUTIONARY THEORY AND THE MARKET COMPETITION

    Nicoleta SIRGHI

    2014-01-01

    Evolutionary theory study of processes that transform economy for firms, institutions, industries, employment, production, trade and growth within, through the actions of diverse agents from experience and interactions, using evolutionary methodology. Evolutionary theory analyses the unleashing of a process of technological and institutional innovation by generating and testing a diversity of ideas which discover and accumulate more survival value for the costs incurred than competing alterna...

  10. The Citation Field of Evolutionary Economics

    Dolfsma, Wilfred; Leydesdorff, Loet

    2010-01-01

    Evolutionary economics has developed into an academic field of its own, institutionalized around, amongst others, the Journal of Evolutionary Economics (JEE). This paper analyzes the way and extent to which evolutionary economics has become an interdisciplinary journal, as its aim was: a journal that is indispensable in the exchange of expert knowledge on topics and using approaches that relate naturally with it. Analyzing citation data for the relevant academic field for the Journal of Evolu...

  11. Evolutionary robotics: what, why, and where to

    Doncieux, Stephane; Bredeche, Nicolas; Mouret, Jean-Baptiste; Eiben, Agoston E. (Gusz)

    2015-01-01

    Evolutionary robotics applies the selection, variation, and heredity principles of natural evolution to the design of robots with embodied intelligence. It can be considered as a subfield of robotics that aims to create more robust and adaptive robots. A pivotal feature of the evolutionary approach is that it considers the whole robot at once, and enables the exploitation of robot features in a holistic manner. Evolutionary robotics can also be seen as an innovative approach to the study of e...

  12. Regional systems of innovation: an evolutionary perspective

    Cooke, P.; M G Uranga; G Etxebarria

    1998-01-01

    The authors develop the concept of regional systems of innovation and relate it to preexisting research on national systems of innovation. They argue that work conducted in the 'new regional science' field is complementary to systems of innovation approaches. They seek to link new regional work to evolutionary economics, and argue for the development of evolutionary regional science. Common elements of interest to evolutionary innovation research and new regional science are important in unde...

  13. DC operating point analysis using evolutionary computing

    Crutchley, DA; Zwolinski, M.

    2004-01-01

    This paper discusses and evaluates a new approach to operating point analysis based on evolutionary computing (EC). EC can find multiple solutions to a problem by using a parallel search through a population. At the operating point(s) of a circuit the overall error has a minimum value. Therefore, we use an Evolutionary Algorithm (EA) to search the solution space to find these minima. Various evolutionary algorithms are described. Several such algorithms have been implemented in a full circuit...

  14. Comparison Study Of Multiobjective Evolutionary Algorithms

    Syomkin, A. M.

    2004-01-01

    Many real-world problems involve two types of difficulties: 1) multiple, conflicting objectives and 2) a highly complex search space. Efficient evolutionary strategies have been developed to deal with both difficulties. Evolutionary algorithms possess several characteristics such as parallelism and robustness that make them preferable to classical optimization methods. In the presented paper I conducted comparison studies among the well-known evolutionary algorithms based on NP-hard 0-1 multi...

  15. Evolutionary Algorithms for the Unit Commitment Problem

    UYAR, A. Şima; Türkay, Belgin

    2008-01-01

    This paper compares three evolutionary computation techniques, namely Steady-State Genetic Algorithms, Evolutionary Strategies and Differential Evolution for the Unit Commitment Problem. The comparison is based on a set of experiments conducted on benchmark datasets as well as on real-world data obtained from the Turkish Interconnected Power System. The results of two state-of-the-art evolutionary approaches, namely a Generational Genetic Algorithm and a Memetic Algorithm for the same...

  16. Evolutionary potential games on lattices

    Szabó, György; Borsos, István

    2016-04-01

    Game theory provides a general mathematical background to study the effect of pair interactions and evolutionary rules on the macroscopic behavior of multi-player games where players with a finite number of strategies may represent a wide scale of biological objects, human individuals, or even their associations. In these systems the interactions are characterized by matrices that can be decomposed into elementary matrices (games) and classified into four types. The concept of decomposition helps the identification of potential games and also the evaluation of the potential that plays a crucial role in the determination of the preferred Nash equilibrium, and defines the Boltzmann distribution towards which these systems evolve for suitable types of dynamical rules. This survey draws parallel between the potential games and the kinetic Ising type models which are investigated for a wide scale of connectivity structures. We discuss briefly the applicability of the tools and concepts of statistical physics and thermodynamics. Additionally the general features of ordering phenomena, phase transitions and slow relaxations are outlined and applied to evolutionary games. The discussion extends to games with three or more strategies. Finally we discuss what happens when the system is weakly driven out of the "equilibrium state" by adding non-potential components representing games of cyclic dominance.

  17. Evolutionary development of tensegrity structures.

    Lobo, Daniel; Vico, Francisco J

    2010-09-01

    Contributions from the emerging fields of molecular genetics and evo-devo (evolutionary developmental biology) are greatly benefiting the field of evolutionary computation, initiating a promise of renewal in the traditional methodology. While direct encoding has constituted a dominant paradigm, indirect ways to encode the solutions have been reported, yet little attention has been paid to the benefits of the proposed methods to real problems. In this work, we study the biological properties that emerge by means of using indirect encodings in the context of form-finding problems. A novel indirect encoding model for artificial development has been defined and applied to an engineering structural-design problem, specifically to the discovery of tensegrity structures. This model has been compared with a direct encoding scheme. While the direct encoding performs similarly well to the proposed method, indirect-based results typically outperform the direct-based results in aspects not directly linked to the nature of the problem itself, but to the emergence of properties found in biological organisms, like organicity, generalization capacity, or modularity aspects which are highly valuable in engineering. PMID:20619314

  18. Evolutionary epistemology a multiparadigm program

    Pinxten, Rik

    1987-01-01

    This volume has its already distant origin in an inter­national conference on Evolutionary Epistemology the editors organized at the University of Ghent in November 1984. This conference aimed to follow up the endeavor started at the ERISS (Epistemologically Relevant Internalist Sociology of Science) conference organized by Don Campbell and Alex Rosen­ berg at Cazenovia Lake, New York, in June 1981, whilst in­ jecting the gist of certain current continental intellectual developments into a debate whose focus, we thought, was in danger of being narrowed too much, considering the still underdeveloped state of affairs in the field. Broadly speaking, evolutionary epistemology today con­ sists of two interrelated, yet qualitatively distinct inves­ tigative efforts. Both are drawing on Darwinian concepts, which may explain why many people have failed to discriminate them. One is the study of the evolution of the cognitive apparatus of living organisms, which is first and foremost the province of biologists and...

  19. The Evolutionary Puzzle of Suicide

    Henri-Jean Aubin

    2013-12-01

    Full Text Available Mechanisms of self-destruction are difficult to reconcile with evolution’s first rule of thumb: survive and reproduce. However, evolutionary success ultimately depends on inclusive fitness. The altruistic suicide hypothesis posits that the presence of low reproductive potential and burdensomeness toward kin can increase the inclusive fitness payoff of self-removal. The bargaining hypothesis assumes that suicide attempts could function as an honest signal of need. The payoff may be positive if the suicidal person has a low reproductive potential. The parasite manipulation hypothesis is founded on the rodent—Toxoplasma gondii host-parasite model, in which the parasite induces a “suicidal” feline attraction that allows the parasite to complete its life cycle. Interestingly, latent infection by T. gondii has been shown to cause behavioral alterations in humans, including increased suicide attempts. Finally, we discuss how suicide risk factors can be understood as nonadaptive byproducts of evolved mechanisms that malfunction. Although most of the mechanisms proposed in this article are largely speculative, the hypotheses that we raise accept self-destructive behavior within the framework of evolutionary theory.

  20. Particle acceleration by combined diffusive shock acceleration and downstream multiple magnetic island acceleration

    Zank, G. P.; Hunana, P.; Mostafavi, P.; le Roux, J. A.; Li, Gang; Webb, G. M.; Khabarova, O.

    2015-09-01

    As a consequence of the evolutionary conditions [28; 29], shock waves can generate high levels of downstream vortical turbulence. Simulations [32-34] and observations [30; 31] support the idea that downstream magnetic islands (also called plasmoids or flux ropes) result from the interaction of shocks with upstream turbulence. Zank et al. [18] speculated that a combination of diffusive shock acceleration (DSA) and downstream reconnection-related effects associated with the dynamical evolution of a “sea of magnetic islands” would result in the energization of charged particles. Here, we utilize the transport theory [18; 19] for charged particles propagating diffusively in a turbulent region filled with contracting and reconnecting plasmoids and small-scale current sheets to investigate a combined DSA and downstream multiple magnetic island charged particle acceleration mechanism. We consider separately the effects of the anti-reconnection electric field that is a consequence of magnetic island merging [17], and magnetic island contraction [14]. For the merging plasmoid reconnection- induced electric field only, we find i) that the particle spectrum is a power law in particle speed, flatter than that derived from conventional DSA theory, and ii) that the solution is constant downstream of the shock. For downstream plasmoid contraction only, we find that i) the accelerated particle spectrum is a power law in particle speed, flatter than that derived from conventional DSA theory; ii) for a given energy, the particle intensity peaks downstream of the shock, and the peak location occurs further downstream of the shock with increasing particle energy, and iii) the particle intensity amplification for a particular particle energy, f(x, c/c0)/f(0, c/c0), is not 1, as predicted by DSA theory, but increases with increasing particle energy. These predictions can be tested against observations of electrons and ions accelerated at interplanetary shocks and the heliospheric

  1. Functional Sites Induce Long-Range Evolutionary Constraints in Enzymes

    Jack, Benjamin R.; Meyer, Austin G.; Echave, Julian; Wilke, Claus O.

    2016-01-01

    Functional residues in proteins tend to be highly conserved over evolutionary time. However, to what extent functional sites impose evolutionary constraints on nearby or even more distant residues is not known. Here, we report pervasive conservation gradients toward catalytic residues in a dataset of 524 distinct enzymes: evolutionary conservation decreases approximately linearly with increasing distance to the nearest catalytic residue in the protein structure. This trend encompasses, on average, 80% of the residues in any enzyme, and it is independent of known structural constraints on protein evolution such as residue packing or solvent accessibility. Further, the trend exists in both monomeric and multimeric enzymes and irrespective of enzyme size and/or location of the active site in the enzyme structure. By contrast, sites in protein–protein interfaces, unlike catalytic residues, are only weakly conserved and induce only minor rate gradients. In aggregate, these observations show that functional sites, and in particular catalytic residues, induce long-range evolutionary constraints in enzymes. PMID:27138088

  2. Evolutionary reduction of developmental plasticity in desert spadefoot toads

    Kulkarni, S.R.; Gómez-Mestre, Iván; Moskalik, C.L.; Storz, B.L.; Buchholz, D.R.

    2011-01-01

    Organisms vary their rates of growth and development in response to environmental inputs. Such developmental plasticity may be adaptive and positively correlate with environmental heterogeneity. However, the evolution of developmental plasticity among closely related taxa is not well understood. To determine the evolutionary pattern of plasticity, we compared plasticity in time to and size at metamorphosis in response to water desiccation in tadpoles among spadefoot species that differ in bre...

  3. Evolutionary Autonomous Health Monitoring System (EAHMS) Project

    National Aeronautics and Space Administration — For supporting NASA's Robotics, Tele-Robotics and Autonomous Systems Roadmap, we are proposing the "Evolutionary Autonomous Health Monitoring System" (EAHMS) for...

  4. Evolutionary Pathways for Asteroid Satellites

    Jacobson, Seth Andrew

    2015-08-01

    The YORP-induced rotational fission hypothesis is a proposed mechanism for the creation of small asteroid binaries, which make up approximately 1/6-th of the near-Earth asteroid and small Main Belt asteroid populations. The YORP effect is a radiative torque that rotationally accelerates asteroids on timescales of thousands to millions of years. As asteroids rotationally accelerate, centrifugal accelerations on material within the body can match gravitational accelerations holding that material in place. When this occurs, that material goes into orbit. Once in orbit that material coalesces into a companion that undergoes continued dynamical evolution.Observations with radar, photometric and direct imaging techniques reveal a diverse array of small asteroid satellites. These systems can be sorted into a number of morphologies according to size, multiplicity of members, dynamical orbit and spin states, and member shapes. For instance, singly synchronous binaries have short separation distances between the two members, rapidly rotating oblate primary members, and tidally locked prolate secondary members. Other confirmed binary morphologies include doubly synchronous, tight asynchronous and wide asynchronous binaries. Related to these binary morphologies are unbound paired asteroid systems and bi-lobate contact binaries.A critical test for the YORP-induced rotational fission hypothesis is whether the binary asteroids produced evolve to the observed binary and related systems. In this talk I will review how this evolution is believed to occur according to gravitational dynamics, mutual body tides and the binary YORP effect.

  5. Calorimetry at industrial electron accelerators

    Miller, Arne; Kovacs, A.

    Calorimetry is a convenient way to measure doses at industrial electron accelerators, where high absorbed doses (1-100 kGy) are delivered at dose rates of 102-105 Gy s-1 or even higher. Water calorimeters have been used for this purpose for several years, but recently other materials such as...

  6. Calorimetry at industrial electron accelerators

    Miller, Arne; Kovacs, A.

    1985-01-01

    Calorimetry is a convenient way to measure doses at industrial electron accelerators, where high absorbed doses (1-100 kGy) are delivered at dose rates of 102-105 Gy s-1 or even higher. Water calorimeters have been used for this purpose for several years, but recently other materials such as...

  7. Application of Plasma Waveguides to High Energy Accelerators

    Milchberg, Howard [Univ. of Maryland, College Park, MD (United States)

    2016-07-01

    This grant supported basic experimental, theoretical and computer simulation research into developing a compact, high pulse repetition rate laser accelerator using the direct laser acceleration mechanism in plasma-based slow wave structures.

  8. Evolutionary Status of Dwarf ``Transition'' Galaxies

    Knezek, Patricia M.; Sembach, Kenneth R.; Gallagher, John S., III

    1999-03-01

    We present deep B-band, R-band, and Hα imaging of three dwarf galaxies: NGC 3377A, NGC 4286, and IC 3475. Based on previous broadband imaging and H I studies, these mixed morphology galaxies have been proposed to be, respectively, a gas-rich low surface brightness Im dwarf, a nucleated dwarf that has lost most of its gas and is in transition from Im to dS0, N, and the prototypical example of a gas-poor ``huge low surface brightness'' early-type galaxy. From the combination of our broadband and Hα imaging with the published information on the neutral gas content of these three galaxies, we find that (1) NGC 3377A is a dwarf spiral, similar to those found by Schombert and coworkers and Matthews & Gallagher; (2) both NGC 3377A and NGC 4286 have comparable amounts of ongoing star formation, as indicated by their Hα emission, while IC 3475 has no detected H II regions to a very low limit; (3) the global star formation rates are at least a factor of 20 below those of 30 Doradus for NGC 3377A and NGC 4286; (4) while the amount of star formation is comparable, the distribution of star-forming regions is very different between NGC 3377A and NGC 4286, with Hα emission scattered over most of the optical face of NGC 3377A and all contained within the inner half of the optical disk of NGC 4286; (5) given their current star formation rates and gas contents, both NGC 3377A and NGC 4286 can continue to form stars for more than a Hubble time; (6) both NGC 3377A and NGC 4286 have integrated total B-R colors that are redder than the integrated total B-R color for IC 3475 and thus it is unlikely that either galaxy will ever evolve into an IC 3475 counterpart; and (7) IC 3475 is too blue to be a dE. We thus conclude that we have not identified potential precursors to galaxies such as IC 3475, and unless significant changes occur in the star formation rates, neither NGC 3377A nor NGC 4286 will evolve into a dwarf elliptical or dwarf spheroidal within a Hubble time. Furthermore

  9. Support for the evolutionary speed hypothesis from intraspecific population genetic data in the non-biting midge Chironomus riparius.

    Oppold, Ann-Marie; Pedrosa, João A M; Bálint, Miklós; Diogo, João B; Ilkova, Julia; Pestana, João L T; Pfenninger, Markus

    2016-02-24

    The evolutionary speed hypothesis (ESH) proposes a causal mechanism for the latitudinal diversity gradient. The central idea of the ESH is that warmer temperatures lead to shorter generation times and increased mutation rates. On an absolute time scale, both should lead to an acceleration of selection and drift. Based on the ESH, we developed predictions regarding the distribution of intraspecific genetic diversity: populations of ectothermic species with more generations per year owing to warmer ambient temperatures should be more differentiated from each other, accumulate more mutations and show evidence for increased mutation rates compared with populations in colder regions. We used the multivoltine insect species Chironomus riparius to test these predictions with cytochrome oxidase I (COI) sequence data and found that populations from warmer regions are indeed significantly more differentiated and have significantly more derived haplotypes than populations from colder regions. We also found a significant correlation of the annual mean temperature with the population mutation parameter θ that serves as a proxy for the per generation mutation rate under certain assumptions. This pattern could be corroborated with two nuclear loci. Overall, our results support the ESH and indicate that the thermal regime experienced may be crucially driving the evolution of ectotherms and may thus ultimately govern their speciation rate. PMID:26888029

  10. Positive selection, relaxation, and acceleration in the evolution of the human and chimp genome.

    Leonardo Arbiza

    2006-04-01

    Full Text Available For years evolutionary biologists have been interested in searching for the genetic bases underlying humanness. Recent efforts at a large or a complete genomic scale have been conducted to search for positively selected genes in human and in chimp. However, recently developed methods allowing for a more sensitive and controlled approach in the detection of positive selection can be employed. Here, using 13,198 genes, we have deduced the sets of genes involved in rate acceleration, positive selection, and relaxation of selective constraints in human, in chimp, and in their ancestral lineage since the divergence from murids. Significant deviations from the strict molecular clock were observed in 469 human and in 651 chimp genes. The more stringent branch-site test of positive selection detected 108 human and 577 chimp positively selected genes. An important proportion of the positively selected genes did not show a significant acceleration in rates, and similarly, many of the accelerated genes did not show significant signals of positive selection. Functional differentiation of genes under rate acceleration, positive selection, and relaxation was not statistically significant between human and chimp with the exception of terms related to G-protein coupled receptors and sensory perception. Both of these were over-represented under relaxation in human in relation to chimp. Comparing differences between derived and ancestral lineages, a more conspicuous change in trends seems to have favored positive selection in the human lineage. Since most of the positively selected genes are different under the same functional categories between these species, we suggest that the individual roles of the alternative positively selected genes may be an important factor underlying biological differences between these species.

  11. Scalable computing for evolutionary genomics.

    Prins, Pjotr; Belhachemi, Dominique; Möller, Steffen; Smant, Geert

    2012-01-01

    Genomic data analysis in evolutionary biology is becoming so computationally intensive that analysis of multiple hypotheses and scenarios takes too long on a single desktop computer. In this chapter, we discuss techniques for scaling computations through parallelization of calculations, after giving a quick overview of advanced programming techniques. Unfortunately, parallel programming is difficult and requires special software design. The alternative, especially attractive for legacy software, is to introduce poor man's parallelization by running whole programs in parallel as separate processes, using job schedulers. Such pipelines are often deployed on bioinformatics computer clusters. Recent advances in PC virtualization have made it possible to run a full computer operating system, with all of its installed software, on top of another operating system, inside a "box," or virtual machine (VM). Such a VM can flexibly be deployed on multiple computers, in a local network, e.g., on existing desktop PCs, and even in the Cloud, to create a "virtual" computer cluster. Many bioinformatics applications in evolutionary biology can be run in parallel, running processes in one or more VMs. Here, we show how a ready-made bioinformatics VM image, named BioNode, effectively creates a computing cluster, and pipeline, in a few steps. This allows researchers to scale-up computations from their desktop, using available hardware, anytime it is required. BioNode is based on Debian Linux and can run on networked PCs and in the Cloud. Over 200 bioinformatics and statistical software packages, of interest to evolutionary biology, are included, such as PAML, Muscle, MAFFT, MrBayes, and BLAST. Most of these software packages are maintained through the Debian Med project. In addition, BioNode contains convenient configuration scripts for parallelizing bioinformatics software. Where Debian Med encourages packaging free and open source bioinformatics software through one central project

  12. Eco-evolutionary dynamics, coding structure and the information threshold

    Hogeweg Paulien

    2010-11-01

    Full Text Available Abstract Background The amount of information that can be maintained in an evolutionary system of replicators is limited by genome length, the number of errors during replication (mutation rate and various external factors that influence the selection pressure. To date, this phenomenon, known as the information threshold, has been studied (both genotypically and phenotypically in a constant environment and with respect to maintenance (as opposed to accumulation of information. Here we take a broader perspective on this problem by studying the accumulation of information in an ecosystem, given an evolvable coding structure. Moreover, our setup allows for individual based as well as ecosystem based solutions. That is, all functions can be performed by individual replicators, or complementing functions can be performed by different replicators. In this setup, where both the ecosystem and the individual genomes can evolve their structure, we study how populations cope with high mutation rates and accordingly how the information threshold might be alleviated. Results We observe that the first response to increased mutation rates is a change in coding structure. At moderate mutation rates evolution leads to longer genomes with a higher diversity than at high mutation rates. Thus, counter-intuitively, at higher mutation rates diversity is reduced and the efficacy of the evolutionary process is decreased. Therefore, moderate mutation rates allow for more degrees of freedom in exploring genotype space during the evolutionary trajectory, facilitating the emergence of solutions. When an individual based solution cannot be attained due to high mutation rates, spatial structuring of the ecosystem can accommodate the evolution of ecosystem based solutions. Conclusions We conclude that the evolutionary freedom (eg. the number of genotypes that can be reached by evolution is increasingly restricted by higher mutation rates. In the case of such severe mutation

  13. An Allele Real-Coded Quantum Evolutionary Algorithm Based on Hybrid Updating Strategy

    Yu-Xian Zhang

    2016-01-01

    Full Text Available For improving convergence rate and preventing prematurity in quantum evolutionary algorithm, an allele real-coded quantum evolutionary algorithm based on hybrid updating strategy is presented. The real variables are coded with probability superposition of allele. A hybrid updating strategy balancing the global search and local search is presented in which the superior allele is defined. On the basis of superior allele and inferior allele, a guided evolutionary process as well as updating allele with variable scale contraction is adopted. And Hε gate is introduced to prevent prematurity. Furthermore, the global convergence of proposed algorithm is proved by Markov chain. Finally, the proposed algorithm is compared with genetic algorithm, quantum evolutionary algorithm, and double chains quantum genetic algorithm in solving continuous optimization problem, and the experimental results verify the advantages on convergence rate and search accuracy.

  14. An Allele Real-Coded Quantum Evolutionary Algorithm Based on Hybrid Updating Strategy.

    Zhang, Yu-Xian; Qian, Xiao-Yi; Peng, Hui-Deng; Wang, Jian-Hui

    2016-01-01

    For improving convergence rate and preventing prematurity in quantum evolutionary algorithm, an allele real-coded quantum evolutionary algorithm based on hybrid updating strategy is presented. The real variables are coded with probability superposition of allele. A hybrid updating strategy balancing the global search and local search is presented in which the superior allele is defined. On the basis of superior allele and inferior allele, a guided evolutionary process as well as updating allele with variable scale contraction is adopted. And H ε gate is introduced to prevent prematurity. Furthermore, the global convergence of proposed algorithm is proved by Markov chain. Finally, the proposed algorithm is compared with genetic algorithm, quantum evolutionary algorithm, and double chains quantum genetic algorithm in solving continuous optimization problem, and the experimental results verify the advantages on convergence rate and search accuracy. PMID:27057159

  15. Acceleration without Horizons

    Doria, Alaric; Munoz, Gerardo

    2015-01-01

    We derive the metric of an accelerating observer moving with non-constant proper acceleration in flat spacetime. With the exception of a limiting case representing a Rindler observer, there are no horizons. In our solution, observers can accelerate to any desired terminal speed $v_{\\infty} < c$. The motion of the accelerating observer is completely determined by the distance of closest approach and terminal velocity or, equivalently, by an acceleration parameter and terminal velocity.

  16. Markov Networks in Evolutionary Computation

    Shakya, Siddhartha

    2012-01-01

    Markov networks and other probabilistic graphical modes have recently received an upsurge in attention from Evolutionary computation community, particularly in the area of Estimation of distribution algorithms (EDAs).  EDAs have arisen as one of the most successful experiences in the application of machine learning methods in optimization, mainly due to their efficiency to solve complex real-world optimization problems and their suitability for theoretical analysis. This book focuses on the different steps involved in the conception, implementation and application of EDAs that use Markov networks, and undirected models in general. It can serve as a general introduction to EDAs but covers also an important current void in the study of these algorithms by explaining the specificities and benefits of modeling optimization problems by means of undirected probabilistic models. All major developments to date in the progressive introduction of Markov networks based EDAs are reviewed in the book. Hot current researc...

  17. Evolutionary Subnetworks in Complex Systems

    Li, Menghui; Lai, Choy-Heng

    2009-01-01

    Links in a practical network may have different functions, which makes the original network a combination of some functional subnetworks. Here, by a model of coupled oscillators, we investigate how such functional subnetworks are evolved and developed according to the network structure and dynamics. In particular, we study the case of evolutionary clustered networks in which the function of each link (either attractive or repulsive coupling) is updated by the local dynamics. It is found that, during the process of system evolution, the network is gradually stabilized into a particular form in which the attractive (repulsive) subnetwork consists only the intralinks (interlinks). Based on the properties of subnetwork evolution, we also propose a new algorithm for network partition which is distinguished by the convenient operation and fast computing speed.

  18. Evolutionary advantages of adaptive rewarding

    Szolnoki, Attila

    2012-01-01

    Our wellbeing depends as much on our personal success, as it does on the success of our society. The realization of this fact makes cooperation a very much needed trait. Experiments have shown that rewards can elevate our readiness to cooperate, but since giving a reward inevitably entails paying a cost for it, the emergence and stability of such behavior remain elusive. Here we show that allowing for the act of rewarding to self-organize in dependence on the success of cooperation creates several evolutionary advantages that instill new ways through which collaborative efforts are promoted. Ranging from indirect territorial battle to the spontaneous emergence and destruction of coexistence, phase diagrams and the underlying spatial patterns reveal fascinatingly reach social dynamics that explains why this costly behavior has evolved and persevered. Comparisons with adaptive punishment, however, uncover an Achilles heel of adaptive rewarding that is due to over-aggression, which in turn hinders optimal utiliz...

  19. Evolutionary Games and Social Conventions

    Hansen, Pelle Guldborg

    2007-01-01

    which any theory of convention must revolve. In response, the so-called evolutionary turn has developed. While retaining the broad framework, in which games are described in terms of strategies and payoffs, this marks a transition from the classical assumptions of perfect rationality and common......Some thirty years ago Lewis published his Convention: A Philosophical Study (Lewis, 2002). This laid the foundation for a game-theoretic approach to social conventions, but became more famously known for its seminal analysis of common knowledge; the concept receiving its canonical analysis in...... Aumann (1976) and which, together with the assumptions of perfect rationality, came to be defining of classical game theory. However, classical game theory is currently undergoing severe crisis as a tool for exploring social phenomena; a crisis emerging from the problem of equilibrium selection around...

  20. Evolutionary origin of cardiac malformations.

    Taussig, H B

    1988-10-01

    The author has proposed in previous publications that isolated cardiac malformations have an evolutionary origin. This is partly supported by the fact that isolated cardiac malformations found in humans occur also in other placental mammals as well as in birds. External gross examination of the heart in just over 5,000 birds was carried out during a 3 year period. Anomalies included one instance of duplicate hearts, two specimens in which no heart could be identified and in a fourth, a yellow-rumped warbler, the heart lay in the neck outside of the thoracic cavity. Published reports of similar occurrences of an ectopically placed heart concern birds, cattle and humans. The fact that various species of both placental mammals and birds show evidence of heritability for heart defects, and that these species cannot interbreed, combined with the fact that birds and mammals have many similar malformations, points to either a common external causative factor or a common origin. Genes that code the malformed heart must be transmitted with that part of the genetic makeup common to all birds and mammals. Malformations caused by teratogens produce widespread organ injury to a potentially normal embryo whereas the evolutionary malformation is an organ-specific anomaly in an otherwise normal mammal or bird and occurs in widely separated species. The implications of this theory are important for parents of children with an isolated congenital heart defect who may have ingested one or another drug or chemical or have been exposed to toxins or infectious agents before or after conception of the affected offspring. PMID:3047192

  1. Evolutionary primacy of sodium bioenergetics

    Wolf Yuri I

    2008-04-01

    Full Text Available Abstract Background The F- and V-type ATPases are rotary molecular machines that couple translocation of protons or sodium ions across the membrane to the synthesis or hydrolysis of ATP. Both the F-type (found in most bacteria and eukaryotic mitochondria and chloroplasts and V-type (found in archaea, some bacteria, and eukaryotic vacuoles ATPases can translocate either protons or sodium ions. The prevalent proton-dependent ATPases are generally viewed as the primary form of the enzyme whereas the sodium-translocating ATPases of some prokaryotes are usually construed as an exotic adaptation to survival in extreme environments. Results We combine structural and phylogenetic analyses to clarify the evolutionary relation between the proton- and sodium-translocating ATPases. A comparison of the structures of the membrane-embedded oligomeric proteolipid rings of sodium-dependent F- and V-ATPases reveals nearly identical sets of amino acids involved in sodium binding. We show that the sodium-dependent ATPases are scattered among proton-dependent ATPases in both the F- and the V-branches of the phylogenetic tree. Conclusion Barring convergent emergence of the same set of ligands in several lineages, these findings indicate that the use of sodium gradient for ATP synthesis is the ancestral modality of membrane bioenergetics. Thus, a primitive, sodium-impermeable but proton-permeable cell membrane that harboured a set of sodium-transporting enzymes appears to have been the evolutionary predecessor of the more structurally demanding proton-tight membranes. The use of proton as the coupling ion appears to be a later innovation that emerged on several independent occasions. Reviewers This article was reviewed by J. Peter Gogarten, Martijn A. Huynen, and Igor B. Zhulin. For the full reviews, please go to the Reviewers' comments section.

  2. Evolutionary design assistants for architecture

    N. Onur Sönmez

    2015-04-01

    Full Text Available In its parallel pursuit of an increased competitivity for design offices and more pleasurable and easier workflows for designers, artificial design intelligence is a technical, intellectual, and political challenge. While human-machine cooperation has become commonplace through Computer Aided Design (CAD tools, a more improved collaboration and better support appear possible only through an endeavor into a kind of artificial design intelligence, which is more sensitive to the human perception of affairs.Considered as part of the broader Computational Design studies, the research program of this quest can be called Artificial / Autonomous / Automated Design (AD. The current available level of Artificial Intelligence (AI for design is limited and a viable aim for current AD would be to develop design assistants that are capable of producing drafts for various design tasks. Thus, the overall aim of this thesis is the development of approaches, techniques, and tools towards artificial design assistants that offer a capability for generating drafts for sub-tasks within design processes. The main technology explored for this aim is Evolutionary Computation (EC, and the target design domain is architecture. The two connected research questions of the study concern, first, the investigation of the ways to develop an architectural design assistant, and secondly, the utilization of EC for the development of such assistants.While developing approaches, techniques, and computational tools for such an assistant, the study also carries out a broad theoretical investigation into the main problems, challenges, and requirements towards such assistants on a rather overall level. Therefore, the research is shaped as a parallel investigation of three main threads interwoven along several levels, moving from a more general level to specific applications. The three research threads comprise, first, theoretical discussions and speculations with regard to both existing

  3. Technology of magnetically driven accelerators

    The marriage of Induction Linac technology with Nonlinear Magnetic Modulators has produced some unique capabilities. It appears possible to produce electron beams with average currents measured in amperes, at gradients exceeding 1 MeV/meter, and with power efficiencies approaching 50%. A 2 MeV, 5 kA electron accelerator has been constructed at the Lawrence Livermore National Laboratory (LLNL) to demonstrate these concepts and to provide a test facility for high brightness sources. The pulse drive for the accelerator is based on state-of-the-art magnetic pulse compressors with very high peak power capability, repetition rates exceeding a kilohertz and excellent reliability. 8 figs., 1 tab

  4. Radiation Transfer of Models of Massive Star Formation. III. The Evolutionary Sequence

    Zhang, Yichen; Tan, Jonathan C.; Hosokawa, Takashi

    2013-01-01

    We present radiation transfer (RT) simulations of evolutionary sequences of massive protostars forming from massive dense cores in environments of high surface densities. The protostellar evolution is calculated with a detailed multi-zone model, with the accretion rate regulated by feedback from an evolving disk-wind outflow cavity. Disk and envelope evolutions are calculated self-consistently. In this framework, an evolutionary track is determined by three environmental initial conditions: t...

  5. Information Geometry and Evolutionary Game Theory

    Harper, Marc

    2009-01-01

    The Shahshahani geometry of evolutionary game theory is realized as the information geometry of the simplex, deriving from the Fisher information metric of the manifold of categorical probability distributions. Some essential concepts in evolutionary game theory are realized information-theoretically. Results are extended to the Lotka-Volterra equation and to multiple population systems.

  6. Handbook of differential equations evolutionary equations

    Dafermos, CM

    2008-01-01

    The material collected in this volume discusses the present as well as expected future directions of development of the field with particular emphasis on applications. The seven survey articles present different topics in Evolutionary PDE's, written by leading experts.- Review of new results in the area- Continuation of previous volumes in the handbook series covering Evolutionary PDEs- Written by leading experts

  7. On the Evolutionary Stability of Bargaining Inefficiency

    Poulsen, Anders

    This paper investigates whether 'tough' bargaining behavior, which gives rise to inefficiency, can be evolutionary stable. We show that in a two-stage Nash Demand Game tough behavior survives. Indeed, almost all the surplus may be wasted. We also study the Ultimatum Game. Here evolutionary...

  8. Algorithmic Mechanism Design of Evolutionary Computation.

    Pei, Yan

    2015-01-01

    We consider algorithmic design, enhancement, and improvement of evolutionary computation as a mechanism design problem. All individuals or several groups of individuals can be considered as self-interested agents. The individuals in evolutionary computation can manipulate parameter settings and operations by satisfying their own preferences, which are defined by an evolutionary computation algorithm designer, rather than by following a fixed algorithm rule. Evolutionary computation algorithm designers or self-adaptive methods should construct proper rules and mechanisms for all agents (individuals) to conduct their evolution behaviour correctly in order to definitely achieve the desired and preset objective(s). As a case study, we propose a formal framework on parameter setting, strategy selection, and algorithmic design of evolutionary computation by considering the Nash strategy equilibrium of a mechanism design in the search process. The evaluation results present the efficiency of the framework. This primary principle can be implemented in any evolutionary computation algorithm that needs to consider strategy selection issues in its optimization process. The final objective of our work is to solve evolutionary computation design as an algorithmic mechanism design problem and establish its fundamental aspect by taking this perspective. This paper is the first step towards achieving this objective by implementing a strategy equilibrium solution (such as Nash equilibrium) in evolutionary computation algorithm. PMID:26257777

  9. On Economic Applications of Evolutionary Game Theory

    Daniel Friedman

    2010-01-01

    Evolutionary games have considerable unrealized potential for modeling substantive economic issues. They promise richer predictions than orthodox game models but often require more extensive specifications. This paper exposits the specification of evolutionary game models and classifies the possible asymptotic behavior for one and two dimensional models.

  10. Oversimplifying Evolutionary Psychology Leads to Explanatory Gaps

    Tate, Chuck; Ledbetter, Jay N.

    2010-01-01

    Comments on Evolutionary psychology: Controversies, questions, prospects, and limitations by Confer et al. They argued that SST cannot explain the existence of either homosexuality or suicide within the human species. We contend that a sufficiently nuanced evolutionary position has no difficulties explaining either phenomenon. Also in this…

  11. 08051 Executive Summary -- Theory of Evolutionary Algorithms

    Arnold, Dirk V.; Auger, Anne; Rowe, Jonathan E.; Witt, Carsten

    2008-01-01

    The 2008 Dagstuhl Seminar "Theory of Evolutionary Algorithms" was the fifth in a firmly established series of biannual events. In the week from Jan. 27, 2008 to Feb. 1, 2008, 47 researchers from nine countries discussed their recent work and trends in evolutionary computation.

  12. Generalized Evolutionary Algorithm based on Tsallis Statistics

    Dukkipati, Ambedkar; Murty, M. Narasimha; Bhatnagar, Shalabh

    2004-01-01

    Generalized evolutionary algorithm based on Tsallis canonical distribution is proposed. The algorithm uses Tsallis generalized canonical distribution to weigh the configurations for `selection' instead of Gibbs-Boltzmann distribution. Our simulation results show that for an appropriate choice of non-extensive index that is offered by Tsallis statistics, evolutionary algorithms based on this generalization outperform algorithms based on Gibbs-Boltzmann distribution.

  13. The Citation Field of Evolutionary Economics

    Dolfsma, Wilfred

    2010-01-01

    Evolutionary economics has developed into an academic field of its own, institutionalized around, amongst others, the Journal of Evolutionary Economics (JEE). This paper analyzes the way and extent to which evolutionary economics has become an interdisciplinary journal, as its aim was: a journal that is indispensable in the exchange of expert knowledge on topics and using approaches that relate naturally with it. Analyzing citation data for the relevant academic field for the Journal of Evolutionary Economics, we use insights from scientometrics and social network analysis to find that, indeed, the JEE is a central player in this interdisciplinary field aiming mostly at understanding technological and regional dynamics. It does not, however, link firmly with the natural sciences (including biology) nor to management sciences, entrepreneurship, and organization studies. Another journal that could be perceived to have evolutionary acumen, the Journal of Economic Issues, does relate to heterodox economics journa...

  14. Evolutionary Psychiatry and Nosology: Prospects and Limitations

    Luc Faucher

    2012-11-01

    Full Text Available In this paper, I explain why evolutionary psychiatry is not where the next revolution in psychiatry will come from. I will proceed as follows. Firstly, I will review some of the problems commonly attributed to current nosologies, more specifically to the DSM. One of these problems is the lack of a clear and consensual definition of mental disorder; I will then examine specific attempts to spell out such a definition that use the evolutionary framework. One definition that deserves particular attention (for a number of reasons that I will mention later, is one put forward by Jerome Wakefield. Despite my sympathy for his position, I must indicate a few reasons why I think his attempt might not be able to resolve the problems related to current nosologies. I suggest that it might be wiser for an evolutionary psychiatrist to adopt the more integrative framework of “treatable conditions” (Cosmides and Tooby, 1999. As it is thought that an evolutionary approach can contribute to transforming the way we look at mental disorders, I will provide the reader with a brief sketch of the basic tenets of evolutionary psychology. The picture of the architecture of the human mind that emerges from evolutionary psychology is thought by some to be the crucial backdrop to identifying specific mental disorders and distinguishing them from normal conditions. I will also provide two examples of how evolutionary thinking is supposed to change our thinking about some disorders. Using the case of depression, I will then show what kind of problems evolutionary explanations of particular psychopathologies encounter. In conclusion, I will evaluate where evolutionary thinking leaves us in regard to what I identify as the main problems of our current nosologies. I’ll then argue that the prospects of evolutionary psychiatry are not good.

  15. Evolutionary model of the growth and size of firms

    Kaldasch, Joachim

    2012-07-01

    The key idea of this model is that firms are the result of an evolutionary process. Based on demand and supply considerations the evolutionary model presented here derives explicitly Gibrat's law of proportionate effects as the result of the competition between products. Applying a preferential attachment mechanism for firms, the theory allows to establish the size distribution of products and firms. Also established are the growth rate and price distribution of consumer goods. Taking into account the characteristic property of human activities to occur in bursts, the model allows also an explanation of the size-variance relationship of the growth rate distribution of products and firms. Further the product life cycle, the learning (experience) curve and the market size in terms of the mean number of firms that can survive in a market are derived. The model also suggests the existence of an invariant of a market as the ratio of total profit to total revenue. The relationship between a neo-classic and an evolutionary view of a market is discussed. The comparison with empirical investigations suggests that the theory is able to describe the main stylized facts concerning the size and growth of firms.

  16. Agricultural management affects evolutionary processes in a migratory songbird

    Perlut, N.G.; Freeman-Gallant, C. R.; Strong, A.M.; Donovan, T.M.; Kilpatrick, C.W.; Zalik, N.J.

    2008-01-01

    Hay harvests have detrimental ecological effects on breeding songbirds, as harvesting results in nest failure. Importantly, whether harvesting also affects evolutionary processes is not known. We explored how hay harvest affected social and genetic mating patterns, and thus, the overall opportunity for sexual selection and evolutionary processes for a ground-nesting songbird, the Savannah sparrow (Passerculus sandwichensis). On an unharvested field, 55% of females were in polygynous associations, and social polygyny was associated with greater rates of extra-pair paternity (EPP). In this treatment, synchrony explained variation in EPP rates, as broods by more synchronous females had more EPP than broods by asynchronous females. In contrast, on a harvested field, simultaneous nest failure caused by haying dramatically decreased the overall incidence of EPP by increasing the occurrence of social monogamy and, apparently, the ability of polygynous males to maintain paternity in their own nests. Despite increased social and genetic monogamy, these haying-mediated changes in mating systems resulted in greater than twofold increase in the opportunity for sexual selection. This effect arose, in part, from a 30% increase in the variance associated with within-pair fertilization success, relative to the unharvested field. This effect was caused by a notable increase (+110%) in variance associated with the quality of social mates following simultaneous nest failure. Because up to 40% of regional habitat is harvested by early June, these data may demonstrate a strong population-level effect on mating systems, sexual selection, and consequently, evolutionary processes. ?? 2008 The Authors.

  17. Virtual gap dielectric wall accelerator

    Caporaso, George James; Chen, Yu-Jiuan; Nelson, Scott; Sullivan, Jim; Hawkins, Steven A

    2013-11-05

    A virtual, moving accelerating gap is formed along an insulating tube in a dielectric wall accelerator (DWA) by locally controlling the conductivity of the tube. Localized voltage concentration is thus achieved by sequential activation of a variable resistive tube or stalk down the axis of an inductive voltage adder, producing a "virtual" traveling wave along the tube. The tube conductivity can be controlled at a desired location, which can be moved at a desired rate, by light illumination, or by photoconductive switches, or by other means. As a result, an impressed voltage along the tube appears predominantly over a local region, the virtual gap. By making the length of the tube large in comparison to the virtual gap length, the effective gain of the accelerator can be made very large.

  18. Intelligent control system for the KEK digital accelerator

    Studies are being conducted to develop a digital accelerator capable of accelerating ions with any charge state, based on the concept of the induction synchrotron. The digital accelerator is a modification of the KEK 500 MeV booster which employs induction acceleration. The digital accelerator is operated at a repetition rate of 10 Hz. The accelerating pulse voltage is dynamically varied from 0 V to 2.4 kV. A novel technique combining the pulse trigger control and intermittent operation of multi-acceleration cells is developed. The acceleration scheme of the digital accelerator is verified by using computer simulations and it is demonstrated at our test facility by using a beam simulator to mimic a circulating beam-bunch signal in the KEK digital accelerator.

  19. High intensity hadron accelerators

    In this paper we give an introductory discussion of high intensity hadron accelerators with special emphasis on the high intensity feature. The topics selected for this discussion are: Types of acclerator - The principal actions of an accelerator are to confine and to accelerate a particle beam. Focusing - This is a discussion of the confinement of single particles. Intensity limitations - These are related to confinement of intense beams of particles. Power economics - Considerations related to acceleration of intense beams of particles. Heavy ion kinematics - The adaptation of accelerators to accelerate all types of heavy ions

  20. The direction of acceleration

    Wilhelm, Thomas; Burde, Jan-Philipp; Lück, Stephan

    2015-11-01

    Acceleration is a physical quantity that is difficult to understand and hence its complexity is often erroneously simplified. Many students think of acceleration as equivalent to velocity, a ˜ v. For others, acceleration is a scalar quantity, which describes the change in speed Δ|v| or Δ|v|/Δt (as opposed to the change in velocity). The main difficulty with the concept of acceleration therefore lies in developing a correct understanding of its direction. The free iOS app AccelVisu supports students in acquiring a correct conception of acceleration by showing acceleration arrows directly at moving objects.

  1. Evolutionary multiobjective optimization of the multi-location transshipment problem

    Belgasmi, Nabil; Ghédira, Khaled; 10.1007/s12351-008-0015-5

    2011-01-01

    We consider a multi-location inventory system where inventory choices at each location are centrally coordinated. Lateral transshipments are allowed as recourse actions within the same echelon in the inventory system to reduce costs and improve service level. However, this transshipment process usually causes undesirable lead times. In this paper, we propose a multiobjective model of the multi-location transshipment problem which addresses optimizing three conflicting objectives: (1) minimizing the aggregate expected cost, (2) maximizing the expected fill rate, and (3) minimizing the expected transshipment lead times. We apply an evolutionary multiobjective optimization approach using the strength Pareto evolutionary algorithm (SPEA2), to approximate the optimal Pareto front. Simulation with a wide choice of model parameters shows the different trades-off between the conflicting objectives.

  2. Genetic Evolutionary Approach for Cutting Forces Prediction in Hard Milling

    Taylan, Fatih; Kayacan, Cengiz

    2011-11-01

    Hard milling is a very common used machining procedure in the last years. Therefore the prediction of cutting forces is important. The paper deals with this prediction using genetic evolutionary programming (GEP) approach to set mathematical expression for out cutting forces. In this study, face milling was performed using DIN1.2842 (90MnCrV8) cold work tool steel, with a hardness of 61 HRC. Experimental parameters were selected using stability measurements and simulations. In the hard milling experiments, cutting force data in a total of three axes were collected. Feed direction (Fx) and tangential direction (Fy) cutting forces generated using genetic evolutionary programming were modelled. Cutting speed and feed rate values were treated as inputs in the models, and average cutting force values as output. Mathematical expressions were created to predict average Fxand Fy forces that can be generated in hard material milling.

  3. Spatial electric load forecasting using an evolutionary heuristic

    E. M. Carreno

    2010-08-01

    Full Text Available A method for spatial electric load forecasting using elements from evolutionary algorithms is presented. The method uses concepts from knowledge extraction algorithms and linguistic rules' representation to characterize the preferences for land use into a spatial database. The future land use preferences in undeveloped zones in the electrical utility service area are determined using an evolutionary heuristic, which considers a stochastic behavior by crossing over similar rules. The method considers development of new zones and also redevelopment of existing ones. The results are presented in future preference maps. The tests in a real system from a midsized city show a high rate of success when results are compared with information gathered from the utility planning department. The most important features of this method are the need for few data and the simplicity of the algorithm, allowing for future scalability.

  4. Inflated impact factors? The true impact of evolutionary papers in non-evolutionary journals.

    Postma, Erik

    2007-01-01

    Amongst the numerous problems associated with the use of impact factors as a measure of quality are the systematic differences in impact factors that exist among scientific fields. While in theory this can be circumvented by limiting comparisons to journals within the same field, for a diverse and multidisciplinary field like evolutionary biology, in which the majority of papers are published in journals that publish both evolutionary and non-evolutionary papers, this is impossible. However, a journal's overall impact factor may well be a poor predictor for the impact of its evolutionary papers. The extremely high impact factors of some multidisciplinary journals, for example, are by many believed to be driven mostly by publications from other fields. Despite plenty of speculation, however, we know as yet very little about the true impact of evolutionary papers in journals not specifically classified as evolutionary. Here I present, for a wide range of journals, an analysis of the number of evolutionary papers they publish and their average impact. I show that there are large differences in impact among evolutionary and non-evolutionary papers within journals; while the impact of evolutionary papers published in multidisciplinary journals is substantially overestimated by their overall impact factor, the impact of evolutionary papers in many of the more specialized, non-evolutionary journals is significantly underestimated. This suggests that, for evolutionary biologists, publishing in high-impact multidisciplinary journals should not receive as much weight as it does now, while evolutionary papers in more narrowly defined journals are currently undervalued. Importantly, however, their ranking remains largely unaffected. While journal impact factors may thus indeed provide a meaningful qualitative measure of impact, a fair quantitative comparison requires a more sophisticated journal classification system, together with multiple field-specific impact statistics per

  5. Inflated impact factors? The true impact of evolutionary papers in non-evolutionary journals.

    Erik Postma

    Full Text Available Amongst the numerous problems associated with the use of impact factors as a measure of quality are the systematic differences in impact factors that exist among scientific fields. While in theory this can be circumvented by limiting comparisons to journals within the same field, for a diverse and multidisciplinary field like evolutionary biology, in which the majority of papers are published in journals that publish both evolutionary and non-evolutionary papers, this is impossible. However, a journal's overall impact factor may well be a poor predictor for the impact of its evolutionary papers. The extremely high impact factors of some multidisciplinary journals, for example, are by many believed to be driven mostly by publications from other fields. Despite plenty of speculation, however, we know as yet very little about the true impact of evolutionary papers in journals not specifically classified as evolutionary. Here I present, for a wide range of journals, an analysis of the number of evolutionary papers they publish and their average impact. I show that there are large differences in impact among evolutionary and non-evolutionary papers within journals; while the impact of evolutionary papers published in multidisciplinary journals is substantially overestimated by their overall impact factor, the impact of evolutionary papers in many of the more specialized, non-evolutionary journals is significantly underestimated. This suggests that, for evolutionary biologists, publishing in high-impact multidisciplinary journals should not receive as much weight as it does now, while evolutionary papers in more narrowly defined journals are currently undervalued. Importantly, however, their ranking remains largely unaffected. While journal impact factors may thus indeed provide a meaningful qualitative measure of impact, a fair quantitative comparison requires a more sophisticated journal classification system, together with multiple field

  6. 2014 CERN Accelerator Schools: Plasma Wake Acceleration

    2014-01-01

    A specialised school on Plasma Wake Acceleration will be held at CERN, Switzerland from 23-29 November, 2014.   This course will be of interest to staff and students in accelerator laboratories, university departments and companies working in or having an interest in the field of new acceleration techniques. Following introductory lectures on plasma and laser physics, the course will cover the different components of a plasma wake accelerator and plasma beam systems. An overview of the experimental studies, diagnostic tools and state of the art wake acceleration facilities, both present and planned, will complement the theoretical part. Topical seminars and a visit of CERN will complete the programme. Further information can be found at: http://cas.web.cern.ch/cas/PlasmaWake2014/CERN-advert.html http://indico.cern.ch/event/285444/

  7. Accelerator vacuum system elements

    Some elements of vacuum systems are investigated. Considerable attention has been given to the investigation into peculiarities in pumping out of a ionoguide for transportation of an accelerated charged particles beam the spread of which often attains a considerable length. The number of pumps over the ionoguide length is experimentally determined. It is shown that as a result of ionoguide warm-up the pumping out time is considerably reduced maximum permissible pressure is decreased by two orders and lesser rate of pump pumping out is required. The investigations have shown that when operating the ionoguide there is no necessity in setting up seals between the ionoguide and magnetodischarged pump. The causes of the phenomenon in which the pressure near the pump is greater than in the end of the ionoguide, are impurities carried in by the pump into the ionoguide volume and the pumping out capacity of the pressure converter

  8. Electron accelerators for radiation sterilization

    Industrial radiation processes using high power electron accelerators are attractive because the throughput rates are very high and the treatment costs per unit of product are often competitive with more conventional chemical processes. The utilization of energy in e-beam processing is more efficient than typical thermal processing. The use of volatiles or toxic chemicals can be avoided. Strict temperature or moisture controls may not be needed. Irradiated materials are usable immediately after processing. These capabilities are unique in that beneficial changes can be induced rapidly in solid materials and preformed products. In recent years, e-beam accelerators have emerged as the preferred alternative for industrial processing as they offer advantages over isotope radiation sources, such as (a) increased public acceptance since the storage, transport and disposal of radioactive material is not an issue; (b) the ability to hook up with the manufacturing process for in-line processing; (c) higher dose rates resulting in high throughputs. During the 1980s and 1990s, accelerator manufacturers dramatically increased the beam power available for high energy equipment. This effort was directed primarily at meeting the demands of the sterilization industry. During this era, the perception that bigger (higher power, higher energy) was always better prevailed, since the operating and capital costs of accelerators did not increase with power and energy as fast as the throughput. High power was needed to maintain low unit costs for the treatment. During the late 1980s and early 1990s, advances in e-beam technology produced new high energy, high power e-beam accelerators suitable for use in sterilization on an industrial scale. These newer designs achieved high levels of reliability and proved to be competitive with gamma sterilization by 60Co and fumigation with EtO. In parallel, technological advances towards 'miniaturization' of accelerators also made it possible to

  9. Evaluation of the environmental equivalent dose rate using area monitors for neutrons in clinical linear accelerators; Avaliacao da taxa de equivalente de dose ambiente utilizando monitores de area para neutrons em aceleradores lineares clinicos

    Salgado, Ana Paula; Pereira, Walsan Wagner; Patrao, Karla C. de Souza; Fonseca, Evaldo S. da, E-mail: asalgado@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Batista, Delano V.S. [Instituto Nacional do Cancer (INCa), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The Neutron Laboratory of the Radioprotection and Dosimetry Institute - IRD/CNEN, Rio de Janeiro, Brazil, initiated studies on the process of calibration of neutron area monitors and the results of the measurements performed at radiotherapy treatment rooms, containing clinical accelerators

  10. San Francisco Accelerator Conference

    'Where are today's challenges in accelerator physics?' was the theme of the open session at the San Francisco meeting, the largest ever gathering of accelerator physicists and engineers

  11. Dielectric Laser Acceleration

    England, R. Joel; Noble, Robert J.; Wu, Ziran; Qi, Minghao

    2013-01-01

    We describe recent advances in the study of particle acceleration using dielectric near-field structures driven by infrared lasers, which we refer to as Dielectric Laser Accelerators. Implications for high energy physics and other applications are discussed.

  12. Standing wave linear accelerator

    Consideration is being given to standing wave linear accelerator containing generator, phase shifter, two accelerating resonator sections, charged particle injector and waveguide bridge. Its first arm is oined up with generator via the phase shifter, the second and the third ones-with accelerating sections and the fourth one - with HF-power absorber. HF-power absorber represents a section of circular diaphragmatic wavequide with transformer with input wave and intrawaveguide output load located between injector and the first accelerating section. The section possesses holes in side walls lying on accelerator axis. The distances between centers of the last cell of the fast accelerating section and the first cell of the second accelerating sectiOn equal (2n+3)lambda/4, where n=1, 2, 3..., lambda - wave length of generator. The suggested system enables to improve by one order spectral characteristics of accelerators as compared to the prototype in which magnetrons are used as generator

  13. Improved plasma accelerator

    Cheng, D. Y.

    1971-01-01

    Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

  14. High Energy Particle Accelerators

    Audio Productions, Inc, New York

    1960-01-01

    Film about the different particle accelerators in the US. Nuclear research in the US has developed into a broad and well-balanced program.Tour of accelerator installations, accelerator development work now in progress and a number of typical experiments with high energy particles. Brookhaven, Cosmotron. Univ. Calif. Berkeley, Bevatron. Anti-proton experiment. Negative k meson experiment. Bubble chambers. A section on an electron accelerator. Projection of new accelerators. Princeton/Penn. build proton synchrotron. Argonne National Lab. Brookhaven, PS construction. Cambridge Electron Accelerator; Harvard/MIT. SLAC studying a linear accelerator. Other research at Madison, Wisconsin, Fixed Field Alternate Gradient Focusing. (FFAG) Oakridge, Tenn., cyclotron. Two-beam machine. Comments : Interesting overview of high energy particle accelerators installations in the US in these early years. .

  15. Evolutionary genomics of animal personality.

    van Oers, Kees; Mueller, Jakob C

    2010-12-27

    Research on animal personality can be approached from both a phenotypic and a genetic perspective. While using a phenotypic approach one can measure present selection on personality traits and their combinations. However, this approach cannot reconstruct the historical trajectory that was taken by evolution. Therefore, it is essential for our understanding of the causes and consequences of personality diversity to link phenotypic variation in personality traits with polymorphisms in genomic regions that code for this trait variation. Identifying genes or genome regions that underlie personality traits will open exciting possibilities to study natural selection at the molecular level, gene-gene and gene-environment interactions, pleiotropic effects and how gene expression shapes personality phenotypes. In this paper, we will discuss how genome information revealed by already established approaches and some more recent techniques such as high-throughput sequencing of genomic regions in a large number of individuals can be used to infer micro-evolutionary processes, historical selection and finally the maintenance of personality trait variation. We will do this by reviewing recent advances in molecular genetics of animal personality, but will also use advanced human personality studies as case studies of how molecular information may be used in animal personality research in the near future. PMID:21078651

  16. Evolutionary advantages of adaptive rewarding

    Our well-being depends on both our personal success and the success of our society. The realization of this fact makes cooperation an essential trait. Experiments have shown that rewards can elevate our readiness to cooperate, but since giving a reward inevitably entails paying a cost for it, the emergence and stability of such behavior remains elusive. Here we show that allowing for the act of rewarding to self-organize in dependence on the success of cooperation creates several evolutionary advantages that instill new ways through which collaborative efforts are promoted. Ranging from indirect territorial battle to the spontaneous emergence and destruction of coexistence, phase diagrams and the underlying spatial patterns reveal fascinatingly rich social dynamics that explain why this costly behavior has evolved and persevered. Comparisons with adaptive punishment, however, uncover an Achilles heel of adaptive rewarding, coming from over-aggression, which in turn hinders optimal utilization of network reciprocity. This may explain why, despite its success, rewarding is not as firmly embedded into our societal organization as punishment. (paper)

  17. Evolutionary dynamics of group fairness.

    Santos, Fernando P; Santos, Francisco C; Paiva, Ana; Pacheco, Jorge M

    2015-08-01

    The emergence and impact of fairness is commonly studied in the context of 2-person games, notably the Ultimatum Game. Often, however, humans face problems of collective action involving more than two individuals where fairness is known to play a very important role, and whose dynamics cannot be inferred from what is known from 2-person games. Here, we propose a generalization of the Ultimatum Game for an arbitrary number of players--the Multiplayer Ultimatum Game. Proposals are made to a group of responders who must individually reject or accept the proposal. If the total number of individual acceptances stands below a given threshold, the offer will be rejected; otherwise, the offer will be accepted, and equally shared by all responders. We investigate the evolution of fairness in populations of individuals by means of evolutionary game theory, providing both analytical insights and results from numerical simulations. We show how imposing stringent consensuses significantly increases the value of the proposals, leading to fairer outcomes and more tolerant players. Furthermore, we show how stochastic effects--such as imitation errors and/or errors when assessing the fitness of others--may further enhance the overall success in reaching fair collective action. PMID:25936348

  18. Maximal Acceleration Is Nonrotating

    Page, Don N.

    1997-01-01

    In a stationary axisymmetric spacetime, the angular velocity of a stationary observer that Fermi-Walker transports its acceleration vector is also the angular velocity that locally extremizes the magnitude of the acceleration of such an observer, and conversely if the spacetime is also symmetric under reversing both t and phi together. Thus a congruence of Nonrotating Acceleration Worldlines (NAW) is equivalent to a Stationary Congruence Accelerating Locally Extremely (SCALE). These congruenc...

  19. Accelerators at school

    Latest subject covered by the CERN Accelerator School was 'Applied Geodesy of Particle Accelerators', which attracted an impressive number of outside participants to CERN for a week in April. Since the forerunners of today's particle accelerators were demonstrated over 50 years ago, the positioning of accelerator components has progressed from the laboratory bench-top to tunnels tens of kilometres long. Despite this phenomenal growth in size, sub-millimetre accuracy is still required

  20. A Solid state accelerator

    We present a solid state accelerator concept utilizing particle acceleration along crystal channels by longitudinal electron plasma waves in a metal. Acceleration gradients of order 100 GV/cm are theoretically possible, but channeling radiation limits the maximum attainable energy to 105 TeV for protons. Beam dechanneling due to multiple scattering is substantially reduced by the high acceleration gradient. Plasma wave dissipation and generation in metals are also discussed

  1. Superconducting accelerator technology

    Modern and future accelerators for high energy and nuclear physics rely increasingly on superconducting components to achieve the required magnetic fields and accelerating fields. This paper presents a practical overview of the phenomenon of superconductivity, and describes the design issues and solutions associated with superconducting magnets and superconducting rf acceleration structures. Further development and application of superconducting components promises increased accelerator performance at reduced electric power cost

  2. Applications of particle accelerators

    Particle accelerators are now widely used in a variety of applications for scientific research, applied physics, medicine, industrial processing, while possible utilisation in power engineering is envisaged. Earlier presentations of this subject, given at previous CERN Accelerator School sessions have been updated with papers contributed to the first European Conference on Accelerators in Applied Research and Technology (ECAART) held in September 1989 in Frankfurt and to the Second European Particle Accelerator Conference in Nice in June 1990. (orig.)

  3. Accelerator development in BARC

    Charged particle accelerators have played crucial role in the field of both basic and applied sciences. This has been possible because the accelerators have been extensively utilized from unraveling the secrets of nature to diverse applications such as implantation, material modification, medical diagnostics and therapy, nuclear energy and clean air and water. The development of accelerators in BARC can be categorized in two broad categories namely proton and heavy ion based accelerators and electron based accelerators. The heavy ion accelerators with sufficiently high energies are currently being used for conducting frontline nuclear and allied research whereas the electron accelerators are being routinely used for various industrial applications. Recently, there is a strong interest for developing the high energy and high intensity accelerators due to their possibility of effective utilization towards concept of energy amplification (Accelerator Driven System), incineration nuclear waste and transmutation. This talk will discuss details of the accelerator development program in BARC with particular emphasis on the recent development at Low Energy High Intensity Proton Accelerator (LEHIPA) Facility in Ion Accelerator Development Division, BARC. (author)

  4. Far field acceleration

    Far fields are propagating electromagnetic waves far from their source, boundary surfaces, and free charges. The general principles governing the acceleration of charged particles by far fields are reviewed. A survey of proposed field configurations is given. The two most important schemes, Inverse Cerenkov acceleration and Inverse free electron laser acceleration, are discussed in detail

  5. The CERN Accelerator School

    2016-01-01

    Introduction to accelerator physics The CERN Accelerator School: Introduction to Accelerator Physics, which should have taken place in Istanbul, Turkey, later this year has now been relocated to Budapest, Hungary.  Further details regarding the new hotel and dates will be made available as soon as possible on a new Indico site at the end of May.

  6. Accelerators and Dinosaurs

    Turner, Michael Stanley

    2003-01-01

    Using naturally occuring particles on which to research might have made accelerators become extinct. But in fact, results from astrophysics have made accelerator physics even more important. Not only are accelerators used in hospitals but they are also being used to understand nature's inner workings by searching for Higgs bosons, CP violation, neutrino mass and dark matter (2 pages)

  7. Acceleration: It's Elementary

    Willis, Mariam

    2012-01-01

    Acceleration is one tool for providing high-ability students the opportunity to learn something new every day. Some people talk about acceleration as taking a student out of step. In actuality, what one is doing is putting a student in step with the right curriculum. Whole-grade acceleration, also called grade-skipping, usually happens between…

  8. The Accelerator Reliability Forum

    Lüdeke, Andreas; Giachino, R

    2014-01-01

    A high reliability is a very important goal for most particle accelerators. The biennial Accelerator Reliability Workshop covers topics related to the design and operation of particle accelerators with a high reliability. In order to optimize the over-all reliability of an accelerator one needs to gather information on the reliability of many different subsystems. While a biennial workshop can serve as a platform for the exchange of such information, the authors aimed to provide a further channel to allow for a more timely communication: the Particle Accelerator Reliability Forum [1]. This contribution will describe the forum and advertise it’s usage in the community.

  9. Preliminary simulation of implants breast through the accelerated partial irradiation technique: coverage rates and homogeneity; Simulacion previa de implates de mama mediante la tecnica de irradiacion parcial acelerada: indices de cubrimiento y homegeneidad

    Moral Sanchez, S. C.; Paula Carranza, B. de; Erzibengoa, M.; Bragado Alvarez, L.; Guisasola Berasetegui, A.

    2013-07-01

    In this work we present and evaluate the process of pre-simulation we have drawn up when it comes to treatments of accelerated partial irradiation of breast. Previous simulation that we will allow you to have greater control over the location of catheters with respect to the area to radiate. The goodness of this procedure is evaluated through representative quality indexes of the implant. (Author)

  10. Robust optimization : formulation, kriging and evolutionary approaches

    Le Riche, Rodolphe

    2014-01-01

    This is a two hours class on robust optimization. It starts with motivations and formulations for robust optimization, and then focuses on approaches based 1) on kriging 2) on evolutionary computation as complementary alternatives.

  11. Evolutionary origins of leadership and followership.

    Van Vugt, Mark

    2006-01-01

    Drawing upon evolutionary logic, leadership is reconceptualized in terms of the outcome of strategic interactions among individuals who are following different, yet complementary, decision rules to solve recurrent coordination problems. This article uses the vast psychological literature on leadership as a database to test several evolutionary hypotheses about the origins of leadership and followership in humans. As expected, leadership correlates with initiative taking, trait measures of intelligence, specific task competencies, and several indicators of generosity. The review finds no link between leadership and dominance. The evolutionary analysis accounts for reliable age, health, and sex differences in leadership emergence. In general, evolutionary theory provides a useful, integrative framework for studying leader-follower relationships and generates various novel research hypotheses. PMID:17201593

  12. A Hybrid Chaotic Quantum Evolutionary Algorithm

    Cai, Y.; Zhang, M.; Cai, H.

    2010-01-01

    A hybrid chaotic quantum evolutionary algorithm is proposed to reduce amount of computation, speed up convergence and restrain premature phenomena of quantum evolutionary algorithm. The proposed algorithm adopts the chaotic initialization method to generate initial population which will form...... a perfect distribution in feasible solution space in advantage of randomicity and non-repetitive ergodicity of chaos, the simple quantum rotation gate to update non-optimal individuals of population to reduce amount of computation, and the hybrid chaotic search strategy to speed up its convergence...... and enhance the global search ability. A large number of tests show that the proposed algorithm has higher convergence speed and better optimizing ability than quantum evolutionary algorithm, real-coded quantum evolutionary algorithm and hybrid quantum genetic algorithm. Tests also show that when chaos...

  13. Still doing evolutionary algorithms with Perl

    Guervos, Juan J Merelo

    2009-01-01

    Algorithm::Evolutionary (A::E from now on) was introduced in 2002, after a talk in YAPC::EU in Munich. 7 years later, A::E is in its 0.67 version (past its "number of the beast" 0.666), and has been used extensively, to the point of being the foundation of much of the (computer) science being done by our research group (and, admittedly, not many others). All is not done, however; now A::E is being integrated with POE so that evolutionary algorithms (EAs) can be combined with all kinds of servers and used in client, servers, and anything in between. In this companion to the talk I will explain what evolutionary algorithms are, what they are being used for, how to do them with Perl (using these or other fine modules found in CPAN) and what evolutionary algorithms can do for Perl at large.

  14. Evolutionary Topology Optimization for Heat Conduction Fields

    LI Jiachun; YE Bangyan; TANG Yong; GUAN Qiming; YANG Xudong

    2006-01-01

    An effective evolutionary method for solving the structural topology design problems of heat conductive fields is presented in this paper. The topology optimization model based on minimizing the heat transport potential capacity dissipation of heat conductive field is then established and the corresponding sensitivity of objective function is derived to determine which elements would be removed of the heat conductive field for having the increment of the objective heat transport potential capacity dissipation minimized. A Filtering technique is employed in sensitivity field to eliminate numerical instabilities in the evolutionary procedure. Numerical examples are presented to demonstrate the validity and the engineering applicability of the evolutionary method by contrast with SIMP method, meanwhile we can come to a conclusion that higher speed of convergence and clearer optimal topology distribution without intermediate elements can be attained by using evolutionary strategy, with the results laying a reliable foundation for the subsequent shape and size optimizations in thermal engineering.

  15. Scheduling Earth Observing Satellites with Evolutionary Algorithms

    Globus, Al; Crawford, James; Lohn, Jason; Pryor, Anna

    2003-01-01

    We hypothesize that evolutionary algorithms can effectively schedule coordinated fleets of Earth observing satellites. The constraints are complex and the bottlenecks are not well understood, a condition where evolutionary algorithms are often effective. This is, in part, because evolutionary algorithms require only that one can represent solutions, modify solutions, and evaluate solution fitness. To test the hypothesis we have developed a representative set of problems, produced optimization software (in Java) to solve them, and run experiments comparing techniques. This paper presents initial results of a comparison of several evolutionary and other optimization techniques; namely the genetic algorithm, simulated annealing, squeaky wheel optimization, and stochastic hill climbing. We also compare separate satellite vs. integrated scheduling of a two satellite constellation. While the results are not definitive, tests to date suggest that simulated annealing is the best search technique and integrated scheduling is superior.

  16. Direct Laser Acceleration in Laser Wakefield Accelerators

    Shaw, Jessica

    2016-01-01

    In this dissertation, the direct laser acceleration (DLA) of ionization-injected electrons in a laser wakefield accelerator (LWFA) operating in the quasi-blowout regime has been investigated through experiment and simulation. In the blowout regime of LWFA, the radiation pressure of an intense laser pulse can push a majority of the plasma electrons out and around the main body of the pulse. The expelled plasma electrons feel the electrostatic field of the relatively-stationary ions and are t...

  17. The evolutionary genetics of canalization.

    Flatt, Thomas

    2005-09-01

    Evolutionary genetics has recently made enormous progress in understanding how genetic variation maps into phenotypic variation. However why some traits are phenotypically invariant despite apparent genetic and environmental changes has remained a major puzzle. In the 1940s, Conrad Hal Waddington coined the concept and term "canalization" to describe the robustness of phenotypes to perturbation; a similar concept was proposed by Waddington's contemporary Ivan Ivanovich Schmalhausen. This paper reviews what has been learned about canalization since Waddington. Canalization implies that a genotype's phenotype remains relatively invariant when individuals of a particular genotype are exposed to different environments (environmental canalization) or when individuals of the same single- or multilocus genotype differ in their genetic background (genetic canalization). Consequently, genetic canalization can be viewed as a particular kind of epistasis, and environmental canalization and phenotypic plasticity are two aspects of the same phenomenon. Canalization results in the accumulation of phenotypically cryptic genetic variation, which can be released after a "decanalizing" event. Thus, canalized genotypes maintain a cryptic potential for expressing particular phenotypes, which are only uncovered under particular decanalizing environmental or genetic conditions. Selection may then act on this newly released genetic variation. The accumulation of cryptic genetic variation by canalization may therefore increase evolvability at the population level by leading to phenotypic diversification under decanalizing conditions. On the other hand, under canalizing conditions, a major part of the segregating genetic variation may remain phenotypically cryptic; canalization may therefore, at least temporarily, constrain phenotypic evolution. Mechanistically, canalization can be understood in terms of transmission patterns, such as epistasis, pleiotropy, and genotype by environment

  18. Wolbachia versus dengue: Evolutionary forecasts.

    Bull, James J; Turelli, Michael

    2013-01-01

    A novel form of biological control is being applied to the dengue virus. The agent is the maternally transmitted bacterium Wolbachia, naturally absent from the main dengue vector, the mosquito Aedes aegypti. Three Wolbachia-based control strategies have been proposed. One is suppression of mosquito populations by large-scale releases of males incompatible with native females; this intervention requires ongoing releases. The other interventions transform wild mosquito populations with Wolbachia that spread via the frequency-dependent fitness advantage of Wolbachia-infected females; those interventions potentially require just a single, local release for area-wide disease control. One of these latter strategies uses Wolbachia that shortens mosquito life, indirectly preventing viral maturation/transmission. The other strategy uses Wolbachia that block viral transmission. All interventions can be undermined by viral, bacterial or mosquito evolution; viral virulence in humans may also evolve. We examine existing theory, experiments and comparative evidence to motivate predictions about evolutionary outcomes. (i) The life-shortening strategy seems the most likely to be thwarted by evolution. (ii) Mosquito suppression has a reasonable chance of working locally, at least in the short term, but long-term success over large areas is challenging. (iii) Dengue blocking faces strong selection for viral resistance but may well persist indefinitely at some level. Virulence evolution is not mathematically predictable, but comparative data provide no precedent for Wolbachia increasing dengue virulence. On balance, our analysis suggests that the considerable possible benefits of these technologies outweigh the known negatives, but the actual risk is largely unknown. PMID:24481199

  19. Evolutionary Design of Controlled Structures

    Masters, Brett P.; Crawley, Edward F.

    1997-01-01

    Basic physical concepts of structural delay and transmissibility are provided for simple rod and beam structures. Investigations show the sensitivity of these concepts to differing controlled-structures variables, and to rational system modeling effects. An evolutionary controls/structures design method is developed. The basis of the method is an accurate model formulation for dynamic compensator optimization and Genetic Algorithm based updating of sensor/actuator placement and structural attributes. One and three dimensional examples from the literature are used to validate the method. Frequency domain interpretation of these controlled structure systems provide physical insight as to how the objective is optimized and consequently what is important in the objective. Several disturbance rejection type controls-structures systems are optimized for a stellar interferometer spacecraft application. The interferometric designs include closed loop tracking optics. Designs are generated for differing structural aspect ratios, differing disturbance attributes, and differing sensor selections. Physical limitations in achieving performance are given in terms of average system transfer function gains and system phase loss. A spacecraft-like optical interferometry system is investigated experimentally over several different optimized controlled structures configurations. Configurations represent common and not-so-common approaches to mitigating pathlength errors induced by disturbances of two different spectra. Results show that an optimized controlled structure for low frequency broadband disturbances achieves modest performance gains over a mass equivalent regular structure, while an optimized structure for high frequency narrow band disturbances is four times better in terms of root-mean-square pathlength. These results are predictable given the nature of the physical system and the optimization design variables. Fundamental limits on controlled performance are discussed

  20. Evolutionary dynamics in a simple model of self-assembly

    Johnston, Iain G.; Ahnert, Sebastian E.; Doye, Jonathan P. K.; Louis, Ard A.

    2011-06-01

    We investigate the evolutionary dynamics of an idealized model for the robust self-assembly of two-dimensional structures called polyominoes. The model includes rules that encode interactions between sets of square tiles that drive the self-assembly process. The relationship between the model’s rule set and its resulting self-assembled structure can be viewed as a genotype-phenotype map and incorporated into a genetic algorithm. The rule sets evolve under selection for specified target structures. The corresponding complex fitness landscape generates rich evolutionary dynamics as a function of parameters such as the population size, search space size, mutation rate, and method of recombination. Furthermore, these systems are simple enough that in some cases the associated model genome space can be completely characterized, shedding light on how the evolutionary dynamics depends on the detailed structure of the fitness landscape. Finally, we apply the model to study the emergence of the preference for dihedral over cyclic symmetry observed for homomeric protein tetramers.

  1. On the evolutionary stage of the interacting binary AU Mon

    Mennickent, R E

    2014-01-01

    We present a study of the evolutionary stage of the interacting binary and Double Periodic Variable AU Monocerotis. A multi-parametric Chi2 minimization is made between the observed parameters and those predicted by the grid of non-conservative and conservative evolutionary models by Van Rensbergen et al., finding the model that best represents the current stellar and system parameters. According to this model, the system started with initial masses 4 M_sun and 3.6 M_sun and orbital period 3.0 days, 196 million years ago, and at present undergoes a Case-B mass-exchange episode. This evolutionary stage is consistent with the reported existence of a circumprimary accretion disk. However, the implied high mass transfer rate contrasts with the absence of significant orbital period change if the mass exchange is conservative. We show that this can occur if the system has recently entered in a non-conservative stage of mass transfer and the efficiency of mass and angular momentum loss satisfy certain conditions.

  2. Evolutionary algorithms, simulated annealing, and Tabu search: a comparative study

    Youssef, Habib; Sait, Sadiq M.; Adiche, Hakim

    1998-10-01

    Evolutionary algorithms, simulated annealing (SA), and Tabu Search (TS) are general iterative algorithms for combinatorial optimization. The term evolutionary algorithm is used to refer to any probabilistic algorithm whose design is inspired by evolutionary mechanisms found in biological species. Most widely known algorithms of this category are Genetic Algorithms (GA). GA, SA, and TS have been found to be very effective and robust in solving numerous problems from a wide range of application domains.Furthermore, they are even suitable for ill-posed problems where some of the parameters are not known before hand. These properties are lacking in all traditional optimization techniques. In this paper we perform a comparative study among GA, SA, and TS. These algorithms have many similarities, but they also possess distinctive features, mainly in their strategies for searching the solution state space. the three heuristics are applied on the same optimization problem and compared with respect to (1) quality of the best solution identified by each heuristic, (2) progress of the search from initial solution(s) until stopping criteria are met, (3) the progress of the cost of the best solution as a function of time, and (4) the number of solutions found at successive intervals of the cost function. The benchmark problem was is the floorplanning of very large scale integrated circuits. This is a hard multi-criteria optimization problem. Fuzzy logic is used to combine all objective criteria into a single fuzzy evaluation function, which is then used to rate competing solutions.

  3. Evolutionary and Functional Relationships in the Truncated Hemoglobin Family.

    Bustamante, Juan P; Radusky, Leandro; Boechi, Leonardo; Estrin, Darío A; Ten Have, Arjen; Martí, Marcelo A

    2016-01-01

    Predicting function from sequence is an important goal in current biological research, and although, broad functional assignment is possible when a protein is assigned to a family, predicting functional specificity with accuracy is not straightforward. If function is provided by key structural properties and the relevant properties can be computed using the sequence as the starting point, it should in principle be possible to predict function in detail. The truncated hemoglobin family presents an interesting benchmark study due to their ubiquity, sequence diversity in the context of a conserved fold and the number of characterized members. Their functions are tightly related to O2 affinity and reactivity, as determined by the association and dissociation rate constants, both of which can be predicted and analyzed using in-silico based tools. In the present work we have applied a strategy, which combines homology modeling with molecular based energy calculations, to predict and analyze function of all known truncated hemoglobins in an evolutionary context. Our results show that truncated hemoglobins present conserved family features, but that its structure is flexible enough to allow the switch from high to low affinity in a few evolutionary steps. Most proteins display moderate to high oxygen affinities and multiple ligand migration paths, which, besides some minor trends, show heterogeneous distributions throughout the phylogenetic tree, again suggesting fast functional adaptation. Our data not only deepens our comprehension of the structural basis governing ligand affinity, but they also highlight some interesting functional evolutionary trends. PMID:26788940

  4. Evolutionary fingerprints in genome-scale networks

    Schütte, Moritz

    2012-01-01

    Mathematical modeling of biological phenomena has experienced increasing interest since new high-throughput technologies give access to growing amounts of molecular data. These modeling approaches are especially able to test hypotheses which are not yet experimentally accessible or guide an experimental setup. One particular attempt investigates the evolutionary dynamics responsible for today's composition of organisms. Computer simulations either propose an evolutionary mechanism and thus re...

  5. An evolutionary advantage for extravagant honesty

    Bullock, Seth

    2011-01-01

    A game-theoretic model of handicap signalling over a pair of signalling channels is introduced in order to determine when one channel has an evolutionary advantage over the other. The stability conditions for honest handicap signalling are presented for a single channel and are shown to conform with the results of prior handicap signalling models. Evolutionary simulations are then used to show that, for a two-channel system in which honest signalling is possible on both channels, the channel ...

  6. The evolutionary neuroscience of tool making

    Stout, D.; Chaminade, T.

    2007-01-01

    The appearance of the first intentionally modified stone tools over 2.5 million years ago marked a watershed in human evolutionary history, expanding the human adaptive niche and initiating a trend of technological elaboration that continues to the present day. However, the cognitive foundations of this behavioral revolution remain controversial, as do its implications for the nature and evolution of modern human technological abilities. Here we shed new light on the neural and evolutionary f...

  7. Epigenetic catalysis in an evolutionary context

    Wallace, Dr. Rodrick

    2009-01-01

    Recent work by Ciliberti et al. finds the spinglass model of regulatory gene networks adapted from neural network studies to have a single giant connected component in a metanetwork space of interaction matrices, permitting only gradual evolutionary transition, in conflict with empirical studies of development in sea urchin species that found evidence for punctuated equilibrium evolutionary transition. Shifting perspective from the highly parallel matrix space to the grammar/syntax of the tim...

  8. Improving DNA Computing Using Evolutionary Techniques

    Godar J. Ibrahim; Tarik A. Rashid; Ahmed T. Sadiq

    2016-01-01

    the field of DNA Computing has attracted many biologists and computer scientists as it has a biological interface, small size and substantial parallelism. DNA computing depends on DNA molecules’ biochemical reactions which they can randomly anneal and they might accidentally cause improper or unattractive computations. This will inspire opportunities to use evolutionary computation via DNA. Evolutionary Computation emphasizes on probabilistic search and optimization methods which are mimickin...

  9. Surrogate model selection for evolutionary multiobjective optimization

    Pilát, M.; Neruda, Roman

    Piscataway : IEEE CS, 2013, s. 1860-1867. ISBN 978-1-4799-0453-2. [CEC 2013. IEEE Congress on Evolutionary Computation. Cancún (MX), 20.06.2013-23.06.2013] R&D Projects: GA ČR GAP202/11/1368 Grant ostatní: GA UK(CZ) 345511 Institutional support: RVO:67985807 Keywords : multiobjective optimization * evolutionary algorithm * meta-model * model selection Subject RIV: IN - Informatics, Computer Science

  10. The Evolutionary Robustness of Forgiveness and Cooperation

    Bó, Pedro Dal

    2012-01-01

    We study the evolutionary robustness of strategies in infinitely repeated prisoners' dilemma games in which players make mistakes with a small probability and are patient. The evolutionary process we consider is given by the replicator dynamics. We show that there are strategies with a uniformly large basin of attraction independently of the size of the population. Moreover, we show that those strategies forgive defections and, assuming that they are symmetric, they cooperate.

  11. The evolutionary position of turtles revised

    Zardoya, Rafael; Meyer, Axel

    2001-01-01

    Consensus on the evolutionary position of turtles within the amniote phylogeny has eluded evolutionary biologists for more than a century. This phylogenetic problem has remained unsolved partly because turtles have such a unique morphology that only few characters can be used to link them with any other group of amniotes. Among the many alternative hypotheses that have been postulated to explain the origin and phylogenetic relationships of turtles, a general agreement among paleontologists em...

  12. Global Optimization with Hybrid Evolutionary Computation

    Bashir, Hassan Abdullahi

    2014-01-01

    An investigation has been made into hybrid systems which include stochastic and deterministic optimization. This thesis aims to provide new and relevant insights into the design of the nature-inspired hybrid optimization paradigms. It combines evolutionary and gradient-based methods. These hybrid evolutionary methods yield improved performance when applied to complex global optimization tasks and recent research has shown many of such hybridization policies.The thesis has three broad contribu...

  13. R. A. Fisher and Evolutionary Theory

    Karlin, Samuel

    1992-01-01

    R. A. Fisher, apart from his fundamental contributions to statistical science, fostered many developments of theoretical evolutionary science. In commemoration of Fisher's birth centenary (1991), this paper highlights several of Fisher's interests in evolutionary processes. These include the "Fundamental Theorem of Natural Selection," studies on the phenomenon of an even sex ratio in natural populations, the "runaway process" of sexual selection and models of polygenic inheritance. Some histo...

  14. Toward an Evolutionary Theory of Production

    Winter, Sidney G.

    2002-01-01

    Production theory in the neoclassical tradition is strong on Abstract generality. Its high level of Abstraction tends to impede understanding of technological change, partly because its perspective on production differs so much from those of engineers, managers and technologists. A more grounded approach is needed for evolutionary economics, since evolutionary thinking sees questions of production as tightly and reciprocally connected with questions of coordination, incentives, and organizati...

  15. An evolutionary basis for pollination ecology

    Willemstein, S.C.

    1987-01-01

    In the introduction and chapter 2 the incentives and way of reasoning are given for the description of an evolutionary basis of pollination ecology. Starting from the until recently rather anecdotical character of the study of pollination ecology as a whole, and in the absence of large-scale correlations of flowerecologically important character states with angiosperm and insect phylogeny (in the sense of Hennig, 1966), an attempt is made to derive directed evolutionary lines (transformation ...

  16. The evolutionary biology of child health

    Crespi, Bernard

    2011-01-01

    I apply evolutionary perspectives and conceptual tools to analyse central issues underlying child health, with emphases on the roles of human-specific adaptations and genomic conflicts in physical growth and development. Evidence from comparative primatology, anthropology, physiology and human disorders indicates that child health risks have evolved in the context of evolutionary changes, along the human lineage, affecting the timing, growth-differentiation phenotypes and adaptive significanc...

  17. Stellar evolutionary models: uncertainties and systematics

    Cassisi, S.

    2005-01-01

    In this last decade, our knowledge of evolutionary and structural properties of stars of different mass and chemical composition is significantly improved. This result has been achieved as a consequence of our improved capability in understanding and describing the physical behavior of stellar matter in the different thermal regimes characteristic of the different stellar mass ranges and/or evolutionary stages. This notwithstanding, current generation of stellar models is still affected by si...

  18. Hybrid evolutionary algorithms to solve scheduling problems

    Minetti, Gabriela F.; Salto, Carolina; Bermúdez, Carlos; Fernandez, Natalia; Alfonso, Hugo; Gallard, Raúl Hector

    2002-01-01

    The choice of a search algorithm can play a vital role in the success of a scheduling application. Evolutionary algorithms (EAs) can be used to solve this kind of combinatorial optimization problems. Compared to conventional heuristics (CH) and local search techniques (LS), EAs are not well suited for fine-tuninf those structures, which are very close to optimal solutions. Therefore, in complex problems, it is essential to build hybrid evolutionary algorithms (HEA) by incorporating CH and/or ...

  19. Ecology and Evolutionary Biology of Arabidopsis

    Pigliucci, Massimo

    2002-01-01

    Arabidopsis thaliana is now widely used as a model system in molecular and developmental biology, as well as in physiology and cell biology. However, ecologists and evolutionary biologists have turned their attention to the mouse ear cress only much more recently and almost reluctantly. The reason for this is the perception that A. thaliana is not particularly interesting ecologically and that it represents an oddity from an evolutionary standpoint. While there is some truth in both these att...

  20. An Evolutionary Account of Technological Development

    Faghihian, Mehrdad

    2015-01-01

    If 'nothing in biology makes sense except in the light of evolution' (Theodosius Dobzhansky, 1973) , then, does nothing in technology make sense except in the light of evolution? This study will seek to construct an evolutionary account of technological development. To this end, it will consider and analyse a variety of theoretical proposals. In this thesis I will survey existing evolutionary accounts found in socio-cultural and engineering sciences, and will evaluate how these theories ...

  1. Evolutionary Music Composition: A Quantitative Approach

    Jensen, Johannes Høydahl

    2011-01-01

    Artificial Evolution has shown great potential in the musical domain. One task in which Evolutionary techniques have shown special promise is in the automatic creation or composition of music. However, a major challenge faced when constructing evolutionary music composition systems is finding a suitable fitness function.Several approaches to fitness have been tried. The most common is interactive evaluation. However, major efficiency challenges with such an approach have inspired the search f...

  2. Derivation of evolutionary payoffs from observable behavior

    Feigel, Alexander; Englander, Avraham; Engel, Assaf

    2008-01-01

    Interpretation of animal behavior, especially as cooperative or selfish, is a challenge for evolutionary theory. Strategy of a competition should follow from corresponding Darwinian payoffs for the available behavioral options. The payoffs and decision making processes, however, are difficult to observe and quantify. Here we present a general method for the derivation of evolutionary payoffs from observable statistics of interactions. The method is applied to combat of male bowl and doily spi...

  3. BEAST: Bayesian evolutionary analysis by sampling trees

    Drummond Alexei J; Rambaut Andrew

    2007-01-01

    Abstract Background The evolutionary analysis of molecular sequence variation is a statistical enterprise. This is reflected in the increased use of probabilistic models for phylogenetic inference, multiple sequence alignment, and molecular population genetics. Here we present BEAST: a fast, flexible software architecture for Bayesian analysis of molecular sequences related by an evolutionary tree. A large number of popular stochastic models of sequence evolution are provided and tree-based m...

  4. BEAST: Bayesian evolutionary analysis by sampling trees

    Drummond, Alexei J.; Rambaut, Andrew

    2007-01-01

    Background: The evolutionary analysis of molecular sequence variation is a statistical enterprise. This is reflected in the increased use of probabilistic models for phylogenetic inference, multiple sequence alignment, and molecular population genetics. Here we present BEAST: a fast, flexible software architecture for Bayesian analysis of molecular sequences related by an evolutionary tree. A large number of popular stochastic models of sequence evolution are provided and tree-based models su...

  5. Evolutionary Ecology Models of Weed Life History

    Dekker, Jack

    2014-01-01

    The limitations of demographic models as well as the opportunities of evolutionary models are reviewed. Flaws associated with demographic models include the confounding effects of plant architecture, representation of heterogeneous individuals in populations, and changes in deme membership confounding covariance structure. Trait-based evolutionary models include FoxPatch which represents weedy Setaria spp. seed behavior with explicit life history process prediction rules and algorithms.

  6. Evolutionary freezing in a competitive population

    Johnson, N F; Leonard, D. J. T.; Hui, P. M.; T. S. Lo(Dept. of Chemical Physics, The Weizmann Institute of Science, Rehovot, Israel)

    1999-01-01

    We show that evolution in a population of adaptive agents, repeatedly competing for a limited resource, can come to an abrupt halt. This transition from evolutionary to non-evolutionary behavior arises as the global resource level is changed, and is reminiscent of a phase transition to a frozen state. Its origin lies in the inductive decision-making of the agents, the limited global information that they possess and the dynamical feedback inherent in the system.

  7. Evolutionary Minority Games: the benefits of imitation

    Metzler, Richard; Horn, Christian

    2002-01-01

    In the original Evolutionary Minority Game, a segregation into two populations with opposing preferences is observed under many circumstances. We show that this segregation becomes more pronounced and more robust if the dynamics are changed slightly, such that strategies with above-average fitness become more frequent. Similar effects occur also for a generalization of the EMG to more than two choices, and for evolutionary dynamics of a different stochastic strategy for the Minority Game.

  8. Stochastic evolutionary dynamics of direct reciprocity

    Lorens A. Imhof; Nowak, Martin A.

    2009-01-01

    Evolutionary game theory is the study of frequency-dependent selection. The success of an individual depends on the frequencies of strategies that are used in the population. We propose a new model for studying evolutionary dynamics in games with a continuous strategy space. The population size is finite. All members of the population use the same strategy. A mutant strategy is chosen from some distribution over the strategy space. The fixation probability of the mutant strategy in the reside...

  9. Evolutionary principles and their practical application

    Hendry, A. P.; Kinnison, M. T.; Heino, M.;

    2011-01-01

    Evolutionary principles are now routinely incorporated into medicine and agriculture. Examples include the design of treatments that slow the evolution of resistance by weeds, pests, and pathogens, and the design of breeding programs that maximize crop yield or quality. Evolutionary principles are...... also increasingly incorporated into conservation biology, natural resource management, and environmental science. Examples include the protection of small and isolated populations from inbreeding depression, the identification of key traits involved in adaptation to climate change, the design of...

  10. GALAXY DOWNSIZING EVIDENCED BY HYBRID EVOLUTIONARY TRACKS

    The stellar-dark halo mass relation of galaxies at different redshifts, Ms(Mh, z), encloses relevant features concerning their physical processes and evolution. This sequence of relations, defined in the range 0 s) and theoretical (Mh) ingredients. As a result of our approach, a unified picture of stellar and halo mass buildup, population migration, and downsizing of galaxies as a function of mass is presented. The inferred average Ms growth histories (GHETs) of the highest and lowest mass galaxies are definitively quite different from the average MAHs, Mh(z), of the corresponding dark halos. Depending on how a given Mh(z) compares with the mass at which the Ms-to-Mh ratio curve peaks at the epoch z, Mhp(z), two evolutionary phases are evidenced: (1) galaxies in an active regime of Ms growth when Mh hp and (2) galaxies in a quiescent or passive regime when Mh>Mhp. The typical Ms at which galaxies transit from the active (star-forming) to the quiescent regime, Mtran, increases with z, log(Mtran/Msun) ∼10.30 + 0.55z, making evident a population downsizing phenomenon. This result agrees with independent observational determinations based on the evolution of the galaxy stellar mass function decomposition into blue and red galaxy populations. The specific star formation rate (SSFR) predicted from the derivative of the GHET is consistent with direct measures of the SSFR for galaxies at different redshifts, though both sets of observational inferences are independent. The average GHETs of galaxies smaller than Mtran at z = 0 (Ms ∼1010.3 Msun, Mh ∼1011.8 Msun) did not reach the quiescent regime, and for them, the lower the mass, the faster the later Ms growth rate (downsizing in SSFR). The GHETs allow us to predict the transition rate in the number density of active to passive population; the predicted values agree with direct estimates of the growth rate in the number density for the (massive) red population up to z ∼ 1. We show that ΛCDM-based models of disk

  11. Assessment of student conceptions of evolutionary trees

    Blacquiere, Luke

    Biologists use evolutionary trees to depict hypotheses about the relationships among taxa. Trees possess lines that represent lineages, internal nodes that represent where lineages become evolutionarily isolated from one another and terminal nodes that represent the taxa under consideration. Interpreting a tree (i.e., "tree-thinking") is an important skill for biologists yet many students struggle when reading evolutionary trees. Common documented misconceptions include using morphological similarity, internal node counting or terminal node proximity, instead of identifying the internal node that represents a most recent common ancestor (MRCA), to determine relationships among taxa. I developed an instrument to assess whether students were using common ancestry or another, non-scientific, strategy to determine relationships among taxa. The study is the first to explicitly test hypotheses about how students approach reading evolutionary trees. To test the hypotheses an instrument was developed. The instrument is the first reliable and valid assessment testing student understanding of how to use most recent common ancestor to interpret evolutionary relationships in tree diagrams. Instructors can use the instrument as a diagnostic tool enabling them to help students learn this challenging concept. This study shows that, contrary to the assertion that students hold misconceptions about evolutionary trees made in the literature, students do not consistently use erroneous strategies when interpreting trees. This study suggests that a constructivist perspective of cognitive structure describes students' conception of evolutionary trees more closely than a misconception perspective.

  12. Evolutionary cell biology: two origins, one objective.

    Lynch, Michael; Field, Mark C; Goodson, Holly V; Malik, Harmit S; Pereira-Leal, José B; Roos, David S; Turkewitz, Aaron P; Sazer, Shelley

    2014-12-01

    All aspects of biological diversification ultimately trace to evolutionary modifications at the cellular level. This central role of cells frames the basic questions as to how cells work and how cells come to be the way they are. Although these two lines of inquiry lie respectively within the traditional provenance of cell biology and evolutionary biology, a comprehensive synthesis of evolutionary and cell-biological thinking is lacking. We define evolutionary cell biology as the fusion of these two eponymous fields with the theoretical and quantitative branches of biochemistry, biophysics, and population genetics. The key goals are to develop a mechanistic understanding of general evolutionary processes, while specifically infusing cell biology with an evolutionary perspective. The full development of this interdisciplinary field has the potential to solve numerous problems in diverse areas of biology, including the degree to which selection, effectively neutral processes, historical contingencies, and/or constraints at the chemical and biophysical levels dictate patterns of variation for intracellular features. These problems can now be examined at both the within- and among-species levels, with single-cell methodologies even allowing quantification of variation within genotypes. Some results from this emerging field have already had a substantial impact on cell biology, and future findings will significantly influence applications in agriculture, medicine, environmental science, and synthetic biology. PMID:25404324

  13. Accelerator optimization using a network control and acquisition system

    Accelerator optimization requires detailed study of many parameters, indicating the need for remote control and automated data acquisition systems. A control and data acquisition system based on a network of commodity PCs and applications with standards based inter-application communication is being built for the l'OASIS accelerator facility. This system allows synchronous acquisition of data at high (> 1 Hz) rates and remote control of the accelerator at low cost, allowing detailed study of the acceleration process

  14. Evolutionary model of an anonymous consumer durable market

    Kaldasch, Joachim

    2011-07-01

    An analytic model is presented that considers the evolution of a market of durable goods. The model suggests that after introduction goods spread always according to a Bass diffusion. However, this phase will be followed by a diffusion process for durable consumer goods governed by a variation-selection-reproduction mechanism and the growth dynamics can be described by a replicator equation. The theory suggests that products play the role of species in biological evolutionary models. It implies that the evolution of man-made products can be arranged into an evolutionary tree. The model suggests that each product can be characterized by its product fitness. The fitness space contains elements of both sites of the market, supply and demand. The unit sales of products with a higher product fitness compared to the mean fitness increase. Durables with a constant fitness advantage replace other goods according to a logistic law. The model predicts in particular that the mean price exhibits an exponential decrease over a long time period for durable goods. The evolutionary diffusion process is directly related to this price decline and is governed by Gompertz equation. Therefore it is denoted as Gompertz diffusion. Describing the aggregate sales as the sum of first, multiple and replacement purchase the product life cycle can be derived. Replacement purchase causes periodic variations of the sales determined by the finite lifetime of the good (Juglar cycles). The model suggests that both, Bass- and Gompertz diffusion may contribute to the product life cycle of a consumer durable. The theory contains the standard equilibrium view of a market as a special case. It depends on the time scale, whether an equilibrium or evolutionary description is more appropriate. The evolutionary framework is used to derive also the size, growth rate and price distribution of manufacturing business units. It predicts that the size distribution of the business units (products) is lognormal

  15. The future of particle accelerators

    Plasma-based accelerators are developing as credible, and compact, accelerators for the future. We review the status and prospects for electron and proton accelerators using laser Wakefield acceleration. (author)

  16. The Exercise–Affect–Adherence Pathway: An Evolutionary Perspective

    Lee, Harold H.; Emerson, Jessica A.; Williams, David M.

    2016-01-01

    The low rates of regular exercise and overall physical activity (PA) in the general population represent a significant public health challenge. Previous research suggests that, for many people, exercise leads to a negative affective response and, in turn, reduced likelihood of future exercise. The purpose of this paper is to examine this exercise–affect–adherence relationship from an evolutionary perspective. Specifically, we argue that low rates of physical exercise in the general population are a function of the evolved human tendency to avoid unnecessary physical exertion. This innate tendency evolved because it allowed our evolutionary ancestors to conserve energy for physical activities that had immediate adaptive utility such as pursuing prey, escaping predators, and engaging in social and reproductive behaviors. The commonly observed negative affective response to exercise is an evolved proximate psychological mechanism through which humans avoid unnecessary energy expenditure. The fact that the human tendencies toward negative affective response to and avoidance of unnecessary physical activities are innate does not mean that they are unchangeable. Indeed, it is only because of human-engineered changes in our environmental conditions (i.e., it is no longer necessary for us to work for our food) that our predisposition to avoid unnecessary physical exertion has become a liability. Thus, it is well within our capabilities to reengineer our environments to once again make PA necessary or, at least, to serve an immediate functional purpose. We propose a two-pronged approach to PA promotion based on this evolutionary functional perspective: first, to promote exercise and other physical activities that are perceived to have an immediate purpose, and second, to instill greater perceived purpose for a wider range of physical activities. We posit that these strategies are more likely to result in more positive (or less negative) affective responses to exercise

  17. Quantifying the Determinants of Evolutionary Dynamics Leading to Drug Resistance.

    Guillaume Chevereau

    Full Text Available The emergence of drug resistant pathogens is a serious public health problem. It is a long-standing goal to predict rates of resistance evolution and design optimal treatment strategies accordingly. To this end, it is crucial to reveal the underlying causes of drug-specific differences in the evolutionary dynamics leading to resistance. However, it remains largely unknown why the rates of resistance evolution via spontaneous mutations and the diversity of mutational paths vary substantially between drugs. Here we comprehensively quantify the distribution of fitness effects (DFE of mutations, a key determinant of evolutionary dynamics, in the presence of eight antibiotics representing the main modes of action. Using precise high-throughput fitness measurements for genome-wide Escherichia coli gene deletion strains, we find that the width of the DFE varies dramatically between antibiotics and, contrary to conventional wisdom, for some drugs the DFE width is lower than in the absence of stress. We show that this previously underappreciated divergence in DFE width among antibiotics is largely caused by their distinct drug-specific dose-response characteristics. Unlike the DFE, the magnitude of the changes in tolerated drug concentration resulting from genome-wide mutations is similar for most drugs but exceptionally small for the antibiotic nitrofurantoin, i.e., mutations generally have considerably smaller resistance effects for nitrofurantoin than for other drugs. A population genetics model predicts that resistance evolution for drugs with this property is severely limited and confined to reproducible mutational paths. We tested this prediction in laboratory evolution experiments using the "morbidostat", a device for evolving bacteria in well-controlled drug environments. Nitrofurantoin resistance indeed evolved extremely slowly via reproducible mutations-an almost paradoxical behavior since this drug causes DNA damage and increases the mutation

  18. Evolutionary Economics, Endogenous Growth Models, and Resource-Advantage Theory

    Shelby D. Hunt

    1997-01-01

    The gap between evolutionary and neoclassical economics remains large. This article proposed that the gap can be narrowed by evolutionary economies developing process theories that can provide evolutionary theoretical foundations for formal models in the neoclassical equilibrium tradition. This article argues that a process of competitions labeled "resource-advantage theory," can provide an evolutionary, theoretical foundation for formal models of endogenous economic growth.

  19. On the structure of acceleration in turbulence

    Liberzon, A.; Lüthi, B.; Holzner, M.; Ott, Søren; Berg, Jacob; Mann, Jakob

    2012-01-01

    Acceleration and spatial velocity gradients are obtained simultaneously in an isotropic turbulent flow via three dimensional particle tracking velocimetry. We observe two distinct populations of intense acceleration events: one in flow regions of strong strain and another in regions of strong...... vorticity. Geometrical alignments with respect to vorticity vector and to the strain eigenvectors, curvature of Lagrangian trajectories and of streamlines for total acceleration, and for its convective part, , are studied in detail. We discriminate the alignment features of total and convective acceleration...... statistics, which are genuine features of turbulent nature from those of kinematic nature. We find pronounced alignment of acceleration with vorticity. Similarly, and especially are predominantly aligned at 45°with the most stretching and compressing eigenvectors of the rate of the strain tensor, , and...

  20. Particle-accelerator decommissioning

    Generic considerations involved in decommissioning particle accelerators are examined. There are presently several hundred accelerators operating in the United States that can produce material containing nonnegligible residual radioactivity. Residual radioactivity after final shutdown is generally short-lived induced activity and is localized in hot spots around the beam line. The decommissioning options addressed are mothballing, entombment, dismantlement with interim storage, and dismantlement with disposal. The recycle of components or entire accelerators following dismantlement is a definite possibility and has occurred in the past. Accelerator components can be recycled either immediately at accelerator shutdown or following a period of storage, depending on the nature of induced activation. Considerations of cost, radioactive waste, and radiological health are presented for four prototypic accelerators. Prototypes considered range from small accelerators having minimal amounts of radioactive mmaterial to a very large accelerator having massive components containing nonnegligible amounts of induced activation. Archival information on past decommissionings is presented, and recommendations concerning regulations and accelerator design that will aid in the decommissioning of an accelerator are given