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Sample records for stringent genetic drift

  1. Biology undergraduates' misconceptions about genetic drift.

    Science.gov (United States)

    Andrews, T M; Price, R M; Mead, L S; McElhinny, T L; Thanukos, A; Perez, K E; Herreid, C F; Terry, D R; Lemons, P P

    2012-01-01

    This study explores biology undergraduates' misconceptions about genetic drift. We use qualitative and quantitative methods to describe students' definitions, identify common misconceptions, and examine differences before and after instruction on genetic drift. We identify and describe five overarching categories that include 16 distinct misconceptions about genetic drift. The accuracy of students' conceptions ranges considerably, from responses indicating only superficial, if any, knowledge of any aspect of evolution to responses indicating knowledge of genetic drift but confusion about the nuances of genetic drift. After instruction, a significantly greater number of responses indicate some knowledge of genetic drift (p = 0.005), but 74.6% of responses still contain at least one misconception. We conclude by presenting a framework that organizes how students' conceptions of genetic drift change with instruction. We also articulate three hypotheses regarding undergraduates' conceptions of evolution in general and genetic drift in particular. We propose that: 1) students begin with undeveloped conceptions of evolution that do not recognize different mechanisms of change; 2) students develop more complex, but still inaccurate, conceptual frameworks that reflect experience with vocabulary but still lack deep understanding; and 3) some new misconceptions about genetic drift emerge as students comprehend more about evolution.

  2. Biology Undergraduates’ Misconceptions about Genetic Drift

    Science.gov (United States)

    Andrews, T. M.; Price, R. M.; Mead, L. S.; McElhinny, T. L.; Thanukos, A.; Perez, K. E.; Herreid, C. F.; Terry, D. R.; Lemons, P. P.

    2012-01-01

    This study explores biology undergraduates’ misconceptions about genetic drift. We use qualitative and quantitative methods to describe students’ definitions, identify common misconceptions, and examine differences before and after instruction on genetic drift. We identify and describe five overarching categories that include 16 distinct misconceptions about genetic drift. The accuracy of students’ conceptions ranges considerably, from responses indicating only superficial, if any, knowledge of any aspect of evolution to responses indicating knowledge of genetic drift but confusion about the nuances of genetic drift. After instruction, a significantly greater number of responses indicate some knowledge of genetic drift (p = 0.005), but 74.6% of responses still contain at least one misconception. We conclude by presenting a framework that organizes how students’ conceptions of genetic drift change with instruction. We also articulate three hypotheses regarding undergraduates’ conceptions of evolution in general and genetic drift in particular. We propose that: 1) students begin with undeveloped conceptions of evolution that do not recognize different mechanisms of change; 2) students develop more complex, but still inaccurate, conceptual frameworks that reflect experience with vocabulary but still lack deep understanding; and 3) some new misconceptions about genetic drift emerge as students comprehend more about evolution. PMID:22949422

  3. The Genetic Drift Inventory: A Tool for Measuring What Advanced Undergraduates Have Mastered about Genetic Drift

    Science.gov (United States)

    Price, Rebecca M.; Andrews, Tessa C.; McElhinny, Teresa L.; Mead, Louise S.; Abraham, Joel K.; Thanukos, Anna; Perez, Kathryn E.

    2014-01-01

    Understanding genetic drift is crucial for a comprehensive understanding of biology, yet it is difficult to learn because it combines the conceptual challenges of both evolution and randomness. To help assess strategies for teaching genetic drift, we have developed and evaluated the Genetic Drift Inventory (GeDI), a concept inventory that measures…

  4. The genetic drift inventory: a tool for measuring what advanced undergraduates have mastered about genetic drift.

    Science.gov (United States)

    Price, Rebecca M; Andrews, Tessa C; McElhinny, Teresa L; Mead, Louise S; Abraham, Joel K; Thanukos, Anna; Perez, Kathryn E

    2014-01-01

    Understanding genetic drift is crucial for a comprehensive understanding of biology, yet it is difficult to learn because it combines the conceptual challenges of both evolution and randomness. To help assess strategies for teaching genetic drift, we have developed and evaluated the Genetic Drift Inventory (GeDI), a concept inventory that measures upper-division students' understanding of this concept. We used an iterative approach that included extensive interviews and field tests involving 1723 students across five different undergraduate campuses. The GeDI consists of 22 agree-disagree statements that assess four key concepts and six misconceptions. Student scores ranged from 4/22 to 22/22. Statements ranged in mean difficulty from 0.29 to 0.80 and in discrimination from 0.09 to 0.46. The internal consistency, as measured with Cronbach's alpha, ranged from 0.58 to 0.88 across five iterations. Test-retest analysis resulted in a coefficient of stability of 0.82. The true-false format means that the GeDI can test how well students grasp key concepts central to understanding genetic drift, while simultaneously testing for the presence of misconceptions that indicate an incomplete understanding of genetic drift. The insights gained from this testing will, over time, allow us to improve instruction about this key component of evolution.

  5. The Genetic Drift Inventory: A Tool for Measuring What Advanced Undergraduates Have Mastered about Genetic Drift

    Science.gov (United States)

    Price, Rebecca M.; Andrews, Tessa C.; McElhinny, Teresa L.; Mead, Louise S.; Abraham, Joel K.; Thanukos, Anna; Perez, Kathryn E.

    2014-01-01

    Understanding genetic drift is crucial for a comprehensive understanding of biology, yet it is difficult to learn because it combines the conceptual challenges of both evolution and randomness. To help assess strategies for teaching genetic drift, we have developed and evaluated the Genetic Drift Inventory (GeDI), a concept inventory that measures upper-division students’ understanding of this concept. We used an iterative approach that included extensive interviews and field tests involving 1723 students across five different undergraduate campuses. The GeDI consists of 22 agree–disagree statements that assess four key concepts and six misconceptions. Student scores ranged from 4/22 to 22/22. Statements ranged in mean difficulty from 0.29 to 0.80 and in discrimination from 0.09 to 0.46. The internal consistency, as measured with Cronbach's alpha, ranged from 0.58 to 0.88 across five iterations. Test–retest analysis resulted in a coefficient of stability of 0.82. The true–false format means that the GeDI can test how well students grasp key concepts central to understanding genetic drift, while simultaneously testing for the presence of misconceptions that indicate an incomplete understanding of genetic drift. The insights gained from this testing will, over time, allow us to improve instruction about this key component of evolution. PMID:24591505

  6. Genetic Drift Suppresses Bacterial Conjugation in Spatially Structured Populations

    Science.gov (United States)

    Freese, Peter D.; Korolev, Kirill S.; Jiménez, José I.; Chen, Irene A.

    2014-02-01

    Conjugation is the primary mechanism of horizontal gene transfer that spreads antibiotic resistance among bacteria. Although conjugation normally occurs in surface-associated growth (e.g., biofilms), it has been traditionally studied in well-mixed liquid cultures lacking spatial structure, which is known to affect many evolutionary and ecological processes. Here we visualize spatial patterns of gene transfer mediated by F plasmid conjugation in a colony of Escherichia coli growing on solid agar, and we develop a quantitative understanding by spatial extension of traditional mass-action models. We found that spatial structure suppresses conjugation in surface-associated growth because strong genetic drift leads to spatial isolation of donor and recipient cells, restricting conjugation to rare boundaries between donor and recipient strains. These results suggest that ecological strategies, such as enforcement of spatial structure and enhancement of genetic drift, could complement molecular strategies in slowing the spread of antibiotic resistance genes.

  7. [Exploration of the concept of genetic drift in genetics teaching of undergraduates].

    Science.gov (United States)

    Wang, Chun-ming

    2016-01-01

    Genetic drift is one of the difficulties in teaching genetics due to its randomness and probability which could easily cause conceptual misunderstanding. The “sampling error" in its definition is often misunderstood because of the research method of “sampling", which disturbs the results and causes the random changes in allele frequency. I analyzed and compared the definitions of genetic drift in domestic and international genetic textbooks, and found that the definitions containing “sampling error" are widely adopted but are interpreted correctly in only a few textbooks. Here, the history of research on genetic drift, i.e., the contributions of Wright, Fisher and Kimura, is introduced. Moreover, I particularly describe two representative articles recently published about genetic drift teaching of undergraduates, which point out that misconceptions are inevitable for undergraduates during the studying process and also provide a preliminary solution. Combined with my own teaching practice, I suggest that the definition of genetic drift containing “sampling error" can be adopted with further interpretation, i.e., “sampling error" is random sampling among gametes when generating the next generation of alleles which is equivalent to a random sampling of all gametes participating in mating in gamete pool and has no relationship with artificial sampling in general genetics studies. This article may provide some help in genetics teaching.

  8. Population differentiation in Pacific salmon: local adaptation, genetic drift, or the environment?

    Science.gov (United States)

    Adkison, Milo D.

    1995-01-01

    Morphological, behavioral, and life-history differences between Pacific salmon (Oncorhynchus spp.) populations are commonly thought to reflect local adaptation, and it is likewise common to assume that salmon populations separated by small distances are locally adapted. Two alternatives to local adaptation exist: random genetic differentiation owing to genetic drift and founder events, and genetic homogeneity among populations, in which differences reflect differential trait expression in differing environments. Population genetics theory and simulations suggest that both alternatives are possible. With selectively neutral alleles, genetic drift can result in random differentiation despite many strays per generation. Even weak selection can prevent genetic drift in stable populations; however, founder effects can result in random differentiation despite selective pressures. Overlapping generations reduce the potential for random differentiation. Genetic homogeneity can occur despite differences in selective regimes when straying rates are high. In sum, localized differences in selection should not always result in local adaptation. Local adaptation is favored when population sizes are large and stable, selection is consistent over large areas, selective diffeentials are large, and straying rates are neither too high nor too low. Consideration of alternatives to local adaptation would improve both biological research and salmon conservation efforts.

  9. The contributions of admixture and genetic drift to diversity among post-contact populations in the Americas.

    Science.gov (United States)

    Koehl, Anthony J; Long, Jeffrey C

    2018-02-01

    We present a model that partitions Nei's minimum genetic distance between admixed populations into components of admixture and genetic drift. We applied this model to 17 admixed populations in the Americas to examine how admixture and drift have contributed to the patterns of genetic diversity. We analyzed 618 short tandem repeat loci in 949 individuals from 49 population samples. Thirty-two samples serve as proxies for continental ancestors. Seventeen samples represent admixed populations: (4) African-American and (13) Latin American. We partition genetic distance, and then calculate fixation indices and principal coordinates to interpret our results. A computer simulation confirms that our method correctly estimates drift and admixture components of genetic distance when the assumptions of the model are met. The partition of genetic distance shows that both admixture and genetic drift contribute to patterns of genetic diversity. The admixture component of genetic distance provides evidence for two distinct axes of continental ancestry. However, the genetic distances show that ancestry contributes to only one axis of genetic differentiation. The genetic distances among the 13 Latin American populations in this analysis show contributions from both differences in ancestry and differences in genetic drift. By contrast, the genetic distances among the four African American populations in this analysis owe mostly to genetic drift because these groups have similar fractions of European and African ancestry. The genetic structure of admixed populations in the Americas reflects more than admixture. We show that the history of serial founder effects constrains the impact of admixture on allele frequencies to a single dimension. Genetic drift in the admixed populations imposed a new level of genetic structure onto that created by admixture. © 2017 Wiley Periodicals, Inc.

  10. The influence of genetic drift and selection on quantitative traits in a plant pathogenic fungus.

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    Stefansson, Tryggvi S; McDonald, Bruce A; Willi, Yvonne

    2014-01-01

    Genetic drift and selection are ubiquitous evolutionary forces acting to shape genetic variation in populations. While their relative importance has been well studied in plants and animals, less is known about their relative importance in fungal pathogens. Because agro-ecosystems are more homogeneous environments than natural ecosystems, stabilizing selection may play a stronger role than genetic drift or diversifying selection in shaping genetic variation among populations of fungal pathogens in agro-ecosystems. We tested this hypothesis by conducting a QST/FST analysis using agricultural populations of the barley pathogen Rhynchosporium commune. Population divergence for eight quantitative traits (QST) was compared with divergence at eight neutral microsatellite loci (FST) for 126 pathogen strains originating from nine globally distributed field populations to infer the effects of genetic drift and types of selection acting on each trait. Our analyses indicated that five of the eight traits had QST values significantly lower than FST, consistent with stabilizing selection, whereas one trait, growth under heat stress (22°C), showed evidence of diversifying selection and local adaptation (QST>FST). Estimates of heritability were high for all traits (means ranging between 0.55-0.84), and average heritability across traits was negatively correlated with microsatellite gene diversity. Some trait pairs were genetically correlated and there was significant evidence for a trade-off between spore size and spore number, and between melanization and growth under benign temperature. Our findings indicate that many ecologically and agriculturally important traits are under stabilizing selection in R. commune and that high within-population genetic variation is maintained for these traits.

  11. Genetic drift and mutational hazard in the evolution of salamander genomic gigantism.

    Science.gov (United States)

    Mohlhenrich, Erik Roger; Mueller, Rachel Lockridge

    2016-12-01

    Salamanders have the largest nuclear genomes among tetrapods and, excepting lungfishes, among vertebrates as a whole. Lynch and Conery (2003) have proposed the mutational-hazard hypothesis to explain variation in genome size and complexity. Under this hypothesis, noncoding DNA imposes a selective cost by increasing the target for degenerative mutations (i.e., the mutational hazard). Expansion of noncoding DNA, and thus genome size, is driven by increased levels of genetic drift and/or decreased mutation rates; the former determines the efficiency with which purifying selection can remove excess DNA, whereas the latter determines the level of mutational hazard. Here, we test the hypothesis that salamanders have experienced stronger long-term, persistent genetic drift than frogs, a related clade with more typically sized vertebrate genomes. To test this hypothesis, we compared dN/dS and Kr/Kc values of protein-coding genes between these clades. Our results do not support this hypothesis; we find that salamanders have not experienced stronger genetic drift than frogs. Additionally, we find evidence consistent with a lower nucleotide substitution rate in salamanders. This result, along with previous work showing lower rates of small deletion and ectopic recombination in salamanders, suggests that a lower mutational hazard may contribute to genomic gigantism in this clade. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  12. QUANTITATIVE GENETICS OF MORPHOLOGICAL DIFFERENTIATION IN PEROMYSCUS. II. ANALYSIS OF SELECTION AND DRIFT.

    Science.gov (United States)

    Lofsvold, David

    1988-01-01

    The hypothesis that the morphological divergence of local populations of Peromyscus is due to random genetic drift was evaluated by testing the proportionality of the among-locality covariance matrix, L, and the additive genetic covariance matrix, G. Overall, significant proportionality of L̂ and Ĝ was not observed, indicating the evolutionary divergence of local populations does not result from random genetic drift. The forces of selection needed to differentiate three taxa of Peromyscus were reconstructed to examine the divergence of species and subspecies. The selection gradients obtained illustrate the inadequacy of univariate analyses of selection by finding that some characters evolve in the direction opposite to the force of selection acting directly on them. A retrospective selection index was constructed using the estimated selection gradients, and truncation selection on this index was used to estimate the minimum selective mortality per generation required to produce the observed change. On any of the time scales used, the proportion of the population that would need to be culled was quite low, the greatest being of the same order of magnitude as the selective intensities observed in extant natural populations. Thus, entirely plausible intensities of directional natural selection can produce species-level differences in a period of time too short to be resolved in the fossil record. © 1988 The Society for the Study of Evolution.

  13. Genetic drift in hypervariable region 1 of the viral genome in persistent hepatitis C virus infection.

    OpenAIRE

    Kato, N; Ootsuyama, Y; Sekiya, H; Ohkoshi, S; Nakazawa, T; Hijikata, M; Shimotohno, K

    1994-01-01

    The hypervariable region 1 (HVR1) of the putative second envelope glycoprotein (gp70) of hepatitis C virus (HCV) contains a sequence-specific immunological B-cell epitope that induces the production of antibodies restricted to the specific viral isolate, and anti-HVR1 antibodies are involved in the genetic drift of HVR1 driven by immunoselection (N. Kato, H. Sekiya, Y. Ootsuyama, T. Nakazawa, M. Hijikata, S. Ohkoshi, and K. Shimotohno, J. Virol. 67:3923-3930, 1993). We further investigated th...

  14. Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra).

    Science.gov (United States)

    Velo-Antón, G; Zamudio, K R; Cordero-Rivera, A

    2012-04-01

    Continental islands offer an excellent opportunity to investigate adaptive processes and to time microevolutionary changes that precede macroevolutionary events. We performed a population genetic study of the fire salamander (Salamandra salamandra), a species that displays unique intraspecific diversity of reproductive strategies, to address the microevolutionary processes leading to phenotypic and genetic differentiation of island, coastal and interior populations. We used eight microsatellite markers to estimate genetic diversity, population structure and demographic parameters in viviparous insular populations and ovoviviparous coastal and interior populations. Our results show considerable genetic differentiation (F(ST) range: 0.06-0.27), and no clear signs of gene flow among populations, except between the large and admixed interior populations. We find no support for island colonization by rafting or intentional/accidental anthropogenic introductions, indicating that rising sea levels were responsible for isolation of the island populations approximately 9000 years ago. Our study provides evidence of rapid genetic differentiation between island and coastal populations, and rapid evolution of viviparity driven by climatic selective pressures on island populations, geographic isolation with genetic drift, or a combination of these factors. Studies of these viviparous island populations in early stages of divergence help us better understand the microevolutionary processes involved in rapid phenotypic shifts.

  15. Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

    Science.gov (United States)

    Velo-Antón, G; Zamudio, K R; Cordero-Rivera, A

    2012-01-01

    Continental islands offer an excellent opportunity to investigate adaptive processes and to time microevolutionary changes that precede macroevolutionary events. We performed a population genetic study of the fire salamander (Salamandra salamandra), a species that displays unique intraspecific diversity of reproductive strategies, to address the microevolutionary processes leading to phenotypic and genetic differentiation of island, coastal and interior populations. We used eight microsatellite markers to estimate genetic diversity, population structure and demographic parameters in viviparous insular populations and ovoviviparous coastal and interior populations. Our results show considerable genetic differentiation (FST range: 0.06–0.27), and no clear signs of gene flow among populations, except between the large and admixed interior populations. We find no support for island colonization by rafting or intentional/accidental anthropogenic introductions, indicating that rising sea levels were responsible for isolation of the island populations approximately 9000 years ago. Our study provides evidence of rapid genetic differentiation between island and coastal populations, and rapid evolution of viviparity driven by climatic selective pressures on island populations, geographic isolation with genetic drift, or a combination of these factors. Studies of these viviparous island populations in early stages of divergence help us better understand the microevolutionary processes involved in rapid phenotypic shifts. PMID:22086081

  16. Blue Tigers, Black Tapirs, & the Pied Raven of the Faroe Islands: Teaching Genetic Drift Using Real-Life Animal Examples

    Science.gov (United States)

    Robischon, Marcel

    2015-01-01

    Genetic drift is a concept of population genetics that is central to understanding evolutionary processes and aspects of conservation biology. It is frequently taught using rather abstract representations. I introduce three real-life zoological examples, based on historical and recent color morphs of tigers, tapirs, and ravens, that can complement…

  17. On theoretical models of gene expression evolution with random genetic drift and natural selection.

    Science.gov (United States)

    Ogasawara, Osamu; Okubo, Kousaku

    2009-11-20

    The relative contributions of natural selection and random genetic drift are a major source of debate in the study of gene expression evolution, which is hypothesized to serve as a bridge from molecular to phenotypic evolution. It has been suggested that the conflict between views is caused by the lack of a definite model of the neutral hypothesis, which can describe the long-run behavior of evolutionary change in mRNA abundance. Therefore previous studies have used inadequate analogies with the neutral prediction of other phenomena, such as amino acid or nucleotide sequence evolution, as the null hypothesis of their statistical inference. In this study, we introduced two novel theoretical models, one based on neutral drift and the other assuming natural selection, by focusing on a common property of the distribution of mRNA abundance among a variety of eukaryotic cells, which reflects the result of long-term evolution. Our results demonstrated that (1) our models can reproduce two independently found phenomena simultaneously: the time development of gene expression divergence and Zipf's law of the transcriptome; (2) cytological constraints can be explicitly formulated to describe long-term evolution; (3) the model assuming that natural selection optimized relative mRNA abundance was more consistent with previously published observations than the model of optimized absolute mRNA abundances. The models introduced in this study give a formulation of evolutionary change in the mRNA abundance of each gene as a stochastic process, on the basis of previously published observations. This model provides a foundation for interpreting observed data in studies of gene expression evolution, including identifying an adequate time scale for discriminating the effect of natural selection from that of random genetic drift of selectively neutral variations.

  18. Disentangling the roles of natural selection and genetic drift in shaping variation at MHC immunity genes.

    Science.gov (United States)

    Sutton, Jolene T; Nakagawa, Shinichi; Robertson, Bruce C; Jamieson, Ian G

    2011-11-01

    The major histocompatibility complex (MHC) forms an integral component of the vertebrate immune response and, due to strong selection pressures, is one of the most polymorphic regions of the entire genome. Despite over 15 years of research, empirical studies offer highly contradictory explanations of the relative roles of different evolutionary forces, selection and genetic drift, acting on MHC genes during population bottlenecks. Here, we take a meta-analytical approach to quantify the results of studies into the effects of bottlenecks on MHC polymorphism. We show that the consequences of selection acting on MHC loci prior to a bottleneck event, combined with drift during the bottleneck, will result in overall loss of MHC polymorphism that is ∼15% greater than loss of neutral genetic diversity. These results are counter to general expectations that selection should maintain MHC polymorphism, but do agree with the results of recent simulation models and at least two empirical studies. Notably, our results suggest that negative frequency-dependent selection could be more important than overdominance for maintaining high MHC polymorphism in pre-bottlenecked populations. © 2011 Blackwell Publishing Ltd.

  19. Comparing the effects of genetic drift and fluctuating selection on genotype frequency changes in the scarlet tiger moth.

    Science.gov (United States)

    O'Hara, R B

    2005-01-22

    One of the recurring arguments in evolutionary biology is whether evolution occurs principally through natural selection or through neutral processes such as genetic drift. A 60-year-long time series of changes in the genotype frequency of a colour polymorphism of the scarlet tiger moth, Callimorpha dominula, was used to compare the relative effects of genetic drift and variable natural selection. The analysis showed that most of the variation in frequency was the result of genetic drift. In addition, although selection was acting, mean fitness barely increased. This supports the 'Red Queen's hypothesis' that long-term improvements in fitness may not occur, because populations have to keep pace with changes in the environment.

  20. High functional diversity in Mycobacterium tuberculosis driven by genetic drift and human demography.

    Directory of Open Access Journals (Sweden)

    Ruth Hershberg

    2008-12-01

    Full Text Available Mycobacterium tuberculosis infects one third of the human world population and kills someone every 15 seconds. For more than a century, scientists and clinicians have been distinguishing between the human- and animal-adapted members of the M. tuberculosis complex (MTBC. However, all human-adapted strains of MTBC have traditionally been considered to be essentially identical. We surveyed sequence diversity within a global collection of strains belonging to MTBC using seven megabase pairs of DNA sequence data. We show that the members of MTBC affecting humans are more genetically diverse than generally assumed, and that this diversity can be linked to human demographic and migratory events. We further demonstrate that these organisms are under extremely reduced purifying selection and that, as a result of increased genetic drift, much of this genetic diversity is likely to have functional consequences. Our findings suggest that the current increases in human population, urbanization, and global travel, combined with the population genetic characteristics of M. tuberculosis described here, could contribute to the emergence and spread of drug-resistant tuberculosis.

  1. Genetic drift evolution under vaccination pressure among H5N1 Egyptian isolates

    Directory of Open Access Journals (Sweden)

    Afifi Manal A

    2011-06-01

    Egypt. Egyptian H5N1-AIVs are constantly undergoing genetic changes and reveal a complex pattern of drifts. These findings raise the concerns about the value of using influenza vaccines in correlation with the development of antigenic drift in influenza epidemics.

  2. The Role of Genetic Drift in Shaping Modern Human Cranial Evolution: A Test Using Microevolutionary Modeling

    Directory of Open Access Journals (Sweden)

    Heather F. Smith

    2011-01-01

    Full Text Available The means by which various microevolutionary processes have acted in the past to produce patterns of cranial variation that characterize modern humans is not thoroughly understood. Applying a microevolutionary framework, within- and among-population variance/covariance (V/CV structure was compared for several functional and developmental modules of the skull across a worldwide sample of modern humans. V/CV patterns in the basicranium, temporal bone, and face are proportional within and among groups, which is consistent with a hypothesis of neutral evolution; however, mandibular morphology deviated from this pattern. Degree of intergroup similarity in facial, temporal bone, and mandibular morphology is significantly correlated with geographic distance; however, much of the variance remains unexplained. These findings provide insight into the evolutionary history of modern human cranial variation by identifying signatures of genetic drift, gene flow, and migration and set the stage for inferences regarding selective pressures that early humans encountered since their initial migrations around the world.

  3. Elucidating the role of genetic drift and natural selection in cork oak differentiation regarding drought tolerance.

    Science.gov (United States)

    Ramírez-Valiente, J A; Lorenzo, Z; Soto, A; Valladares, F; Gil, L; Aranda, I

    2009-09-01

    Drought is the main selection agent in Mediterranean ecosystems and it has been suggested as an important evolutionary force responsible for population diversification in these types of environments. However, population divergence in quantitative traits can be driven by either natural selection, genetic drift or both. To investigate the roles of these forces on among-population divergence in ecophysiological traits related to drought tolerance (carbon isotope discrimination, specific leaf area, leaf size and leaf nitrogen content), we compared molecular and quantitative genetic differentiation in a common garden experiment including thirteen cork oak (Quercus suber L.) populations across a gradient of rainfall and temperature. Population differentiation for height, specific leaf area, leaf size and nitrogen leaf content measured during a dry year far exceeded the molecular differentiation measured by six nuclear microsatellites. Populations from dry-cool sites showed the lowest nitrogen leaf content and the smallest and thickest leaves contrasting with those from humid-warm sites. These results suggest (i) these traits are subjected to divergence selection and (ii) the genetic differences among populations are partly due to climate adaptation. By contrast, the low among-population divergence found in basal diameter, annual growth and carbon isotopic discrimination (a surrogate for water use efficiency) suggests low or no divergence selection for these traits. Among-population differentiation for neutral markers was not a good predictor for differentiation regarding the quantitative traits studied here, except for leaf size. The correlation observed between the genetic differentiation for leaf size and that for molecular markers was exclusively due to the association between leaf size and the microsatellite QpZAG46, which suggests a possible linkage between QpZAG46 and genes encoding for leaf size.

  4. Drift, selection, or migration? Processes affecting genetic differentiation and variation along a latitudinal gradient in an amphibian.

    Science.gov (United States)

    Cortázar-Chinarro, Maria; Lattenkamp, Ella Z; Meyer-Lucht, Yvonne; Luquet, Emilien; Laurila, Anssi; Höglund, Jacob

    2017-08-14

    Past events like fluctuations in population size and post-glacial colonization processes may influence the relative importance of genetic drift, migration and selection when determining the present day patterns of genetic variation. We disentangle how drift, selection and migration shape neutral and adaptive genetic variation in 12 moor frog populations along a 1700 km latitudinal gradient. We studied genetic differentiation and variation at a MHC exon II locus and a set of 18 microsatellites. Using outlier analyses, we identified the MHC II exon 2 (corresponding to the β-2 domain) locus and one microsatellite locus (RCO8640) to be subject to diversifying selection, while five microsatellite loci showed signals of stabilizing selection among populations. STRUCTURE and DAPC analyses on the neutral microsatellites assigned populations to a northern and a southern cluster, reflecting two different post-glacial colonization routes found in previous studies. Genetic variation overall was lower in the northern cluster. The signature of selection on MHC exon II was weaker in the northern cluster, possibly as a consequence of smaller and more fragmented populations. Our results show that historical demographic processes combined with selection and drift have led to a complex pattern of differentiation along the gradient where some loci are more divergent among populations than predicted from drift expectations due to diversifying selection, while other loci are more uniform among populations due to stabilizing selection. Importantly, both overall and MHC genetic variation are lower at northern latitudes. Due to lower evolutionary potential, the low genetic variation in northern populations may increase the risk of extinction when confronted with emerging pathogens and climate change.

  5. U-251 revisited: genetic drift and phenotypic consequences of long-term cultures of glioblastoma cells

    International Nuclear Information System (INIS)

    Torsvik, Anja; Stieber, Daniel; Enger, Per Øyvind; Golebiewska, Anna; Molven, Anders; Svendsen, Agnete; Westermark, Bengt; Niclou, Simone P; Olsen, Thale Kristin; Chekenya Enger, Martha; Bjerkvig, Rolf

    2014-01-01

    It is well known that in vitro subculture represents a selection pressure on cell lines, and over time this may result in a genetic drift in the cancer cells. In addition, long-term cultures harbor the risk of cross-contamination with other cell lines. The consequences may have major impact on experimental results obtained in various laboratories, where the cell lines no longer reflect the original tumors that they are supposed to represent. Much neglected in the scientific community is a close monitoring of cell cultures by regular phenotypic and genetic characterization. In this report, we present a thorough characterization of the commonly used glioblastoma (GBM) model U-251, which in numerous publications has been wrongly identified as U-373, due to an earlier cross-contamination. In this work, the original U-251 and three subclones of U-251, commonly referred to as U-251 or U-373, were analyzed with regard to their DNA profile, morphology, phenotypic expression, and growth pattern. By array comparative genomic hybridization (aCGH), we show that only the original low-passaged U-251 cells, established in the 1960s, maintain a DNA copy number resembling a typical GBM profile, whereas all long-term subclones lost the typical GBM profile. Also the long-term passaged subclones displayed variations in phenotypic marker expression and showed an increased growth rate in vitro and a more aggressive growth in vivo. Taken together, the variations in genotype and phenotype as well as differences in growth characteristics may explain different results reported in various laboratories related to the U-251 cell line

  6. Major histocompatibility complex variation in insular populations of the Egyptian vulture: inferences about the roles of genetic drift and selection.

    Science.gov (United States)

    Agudo, Rosa; Alcaide, Miguel; Rico, Ciro; Lemus, Jesus A; Blanco, Guillermo; Hiraldo, Fernando; Donázar, Jose A

    2011-06-01

    Insular populations have attracted the attention of evolutionary biologists because of their morphological and ecological peculiarities with respect to their mainland counterparts. Founder effects and genetic drift are known to distribute neutral genetic variability in these demes. However, elucidating whether these evolutionary forces have also shaped adaptive variation is crucial to evaluate the real impact of reduced genetic variation in small populations. Genes of the major histocompatibility complex (MHC) are classical examples of evolutionarily relevant loci because of their well-known role in pathogen confrontation and clearance. In this study, we aim to disentangle the partial roles of genetic drift and natural selection in the spatial distribution of MHC variation in insular populations. To this end, we integrate the study of neutral (22 microsatellites and one mtDNA locus) and MHC class II variation in one mainland (Iberia) and two insular populations (Fuerteventura and Menorca) of the endangered Egyptian vulture (Neophron percnopterus). Overall, the distribution of the frequencies of individual MHC alleles (n=17 alleles from two class II B loci) does not significantly depart from neutral expectations, which indicates a prominent role for genetic drift over selection. However, our results point towards an interesting co-evolution of gene duplicates that maintains different pairs of divergent alleles in strong linkage disequilibrium on islands. We hypothesize that the co-evolution of genes may counteract the loss of genetic diversity in insular demes, maximize antigen recognition capabilities when gene diversity is reduced, and promote the co-segregation of the most efficient allele combinations to cope with local pathogen communities. © 2011 Blackwell Publishing Ltd.

  7. Random genetic drift, natural selection, and noise in human cranial evolution.

    Science.gov (United States)

    Roseman, Charles C

    2016-08-01

    This study assesses the extent to which relationships among groups complicate comparative studies of adaptation in recent human cranial variation and the extent to which departures from neutral additive models of evolution hinder the reconstruction of population relationships among groups using cranial morphology. Using a maximum likelihood evolutionary model fitting approach and a mixed population genomic and cranial data set, I evaluate the relative fits of several widely used models of human cranial evolution. Moreover, I compare the goodness of fit of models of cranial evolution constrained by genomic variation to test hypotheses about population specific departures from neutrality. Models from population genomics are much better fits to cranial variation than are traditional models from comparative human biology. There is not enough evolutionary information in the cranium to reconstruct much of recent human evolution but the influence of population history on cranial variation is strong enough to cause comparative studies of adaptation serious difficulties. Deviations from a model of random genetic drift along a tree-like population history show the importance of environmental effects, gene flow, and/or natural selection on human cranial variation. Moreover, there is a strong signal of the effect of natural selection or an environmental factor on a group of humans from Siberia. The evolution of the human cranium is complex and no one evolutionary process has prevailed at the expense of all others. A holistic unification of phenome, genome, and environmental context, gives us a strong point of purchase on these problems, which is unavailable to any one traditional approach alone. Am J Phys Anthropol 160:582-592, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. Impact of antigenic and genetic drift on the serologic surveillance of H5N2 avian influenza viruses

    Directory of Open Access Journals (Sweden)

    Lucio Eduardo

    2010-12-01

    Full Text Available Abstract Background Serologic surveillance of Avian Influenza (AI viruses is carried out by the hemagglutination inhibition (HI test using reference reagents. This method is recommended by animal health organizations as a standard test to detect antigenic differences (subtypes between circulating influenza virus, vaccine- and/or reference- strains. However, significant discrepancies between reference antisera and field isolates have been observed during serosurveillance of influenza A viruses in pig and poultry farms. The objective of this study was to examine the effects of influenza virus genetic and antigenic drift on serologic testing using standard HI assays and reference reagents. Low pathogenic AI H5N2 viruses isolated in Mexico between 1994 and 2008 were used for phylogenetic analysis of AI hemagglutinin genes and for serologic testing using antisera produced with year-specific AI virus isolates. Results Phylogenetic analysis revealed significant divergence between early LPAI H5N2 viruses (1994 - 1998 and more recent virus field isolates (2002 - 2008. Results of the HI test were markedly influenced by the selection of the AI H5N2 virus (year of isolation used as reference antigen for the assay. These analyses indicate that LPAI H5N2 viruses in Mexico are constantly undergoing genetic drift and that serosurveillance of AI viruses is significantly influenced by the antigen or antisera used for the HI test. Conclusions Reference viral antigens and/or antisera need to be replaced constantly during surveillance of AI viruses to keep pace with the AI antigenic drift. This strategy should improve the estimation of antigenic differences between circulating AI viruses and the selection of suitable vaccine strains.

  9. The roles of genetic drift and natural selection in quantitative trait divergence along an altitudinal gradient in Arabidopsis thaliana.

    Science.gov (United States)

    Luo, Y; Widmer, A; Karrenberg, S

    2015-02-01

    Understanding how natural selection and genetic drift shape biological variation is a central topic in biology, yet our understanding of the agents of natural selection and their target traits is limited. We investigated to what extent selection along an altitudinal gradient or genetic drift contributed to variation in ecologically relevant traits in Arabidopsis thaliana. We collected seeds from 8 to 14 individuals from each of 14 A. thaliana populations originating from sites between 800 and 2700 m above sea level in the Swiss Alps. Seed families were grown with and without vernalization, corresponding to winter-annual and summer-annual life histories, respectively. We analyzed putatively neutral genetic divergence between these populations using 24 simple sequence repeat markers. We measured seven traits related to growth, phenology and leaf morphology that are rarely reported in A. thaliana and performed analyses of altitudinal clines, as well as overall QST-FST comparisons and correlation analyses among pair-wise QST, FST and altitude of origin differences. Multivariate analyses suggested adaptive differentiation along altitude in the entire suite of traits, particularly when expressed in the summer-annual life history. Of the individual traits, a decrease in rosette leaf number in the vegetative state and an increase in leaf succulence with increasing altitude could be attributed to adaptive divergence. Interestingly, these patterns relate well to common within- and between-species trends of smaller plant size and thicker leaves at high altitude. Our results thus offer exciting possibilities to unravel the underlying mechanisms for these conspicuous trends using the model species A. thaliana.

  10. Drifting to oblivion? Rapid genetic differentiation in an endangered lizard following habitat fragmentation and drought

    Science.gov (United States)

    Vandergast, Amy; Wood, Dustin A.; Thompson, Andrew R.; Fisher, Mark; Barrows, Cameron W.; Grant, Tyler J.

    2016-01-01

    Aim The frequency and severity of habitat alterations and disturbance are predicted to increase in upcoming decades, and understanding how disturbance affects population integrity is paramount for adaptive management. Although rarely is population genetic sampling conducted at multiple time points, pre- and post-disturbance comparisons may provide one of the clearest methods to measure these impacts. We examined how genetic properties of the federally threatened Coachella Valley fringe-toed lizard (Uma inornata) responded to severe drought and habitat fragmentation across its range. Location Coachella Valley, California, USA. Methods We used 11 microsatellites to examine population genetic structure and diversity in 1996 and 2008, before and after a historic drought. We used Bayesian assignment methods and F-statistics to estimate genetic structure. We compared allelic richness across years to measure loss of genetic diversity and employed approximate Bayesian computing methods and heterozygote excess tests to explore the recent demographic history of populations. Finally, we compared effective population size across years and to abundance estimates to determine whether diversity remained low despite post-drought recovery. Results Genetic structure increased between sampling periods, likely as a result of population declines during the historic drought of the late 1990s–early 2000s, and habitat loss and fragmentation that precluded post-drought genetic rescue. Simulations supported recent demographic declines in 3 of 4 main preserves, and in one preserve, we detected significant loss of allelic richness. Effective population sizes were generally low across the range, with estimates ≤100 in most sites. Main conclusions Fragmentation and drought appear to have acted synergistically to induce genetic change over a short time frame. Progressive deterioration of connectivity, low Ne and measurable loss of genetic diversity suggest that conservation efforts have

  11. Swimming against the current: genetic structure, host mobility and the drift paradox in trematode parasites

    Czech Academy of Sciences Publication Activity Database

    Blasco-Costa, Maria Isabel; Waters, J. M.; Poulin, R.

    2012-01-01

    Roč. 21, č. 1 (2012), s. 207-217 ISSN 0962-1083 Institutional support: RVO:60077344 Keywords : freshwater * genetic diversity loss * linear ecosystems * population genetic structure Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 6.275, year: 2012 http://onlinelibrary.wiley.com/doi/10.1111/j.1365-294X.2011.05374.x/pdf

  12. Genetic drift of HA and NA in Danish swine influenza virus from the period 2003-2012

    DEFF Research Database (Denmark)

    Fobian, Kristina; Breum, Solvej Østergaard; Hjulsager, Charlotte Kristiane

    2012-01-01

    . Currently at least three influenza A subtypes (H1N1, H1N2 and H3N2) are endemic in the Danish swine population, and since 2010 the pandemic virus (H1N1pdm09) have also frequently been detected. The focus in this study will be on H1N1 and H1N2, since the prevalence of H3N2 have declined over the past years......-titers obtained by testing against a panel of reference swine influenza virus antisera are used for antigenic cartography. Preliminary phylogenetic analyses indicate a higher degree of drift for H1 genes than N1 genes. The antigenic and genetic characterization of the swine influenza virus isolates in this study...

  13. Balancing selection, random genetic drift, and genetic variation at the major histocompatibility complex in two wild populations of guppies (Poecilia reticulata).

    Science.gov (United States)

    Van Oosterhout, Cock; Joyce, Domino A; Cummings, Stephen M; Blais, Jonatan; Barson, Nicola J; Ramnarine, Indar W; Mohammed, Ryan S; Persad, Nadia; Cable, Joanne

    2006-12-01

    Our understanding of the evolution of genes of the major histocompatibility complex (MHC) is rapidly increasing, but there are still enigmatic questions remaining, particularly regarding the maintenance of high levels of MHC polymorphisms in small, isolated populations. Here, we analyze the genetic variation at eight microsatellite loci and sequence variation at exon 2 of the MHC class IIB (DAB) genes in two wild populations of the Trinidadian guppy, Poecilia reticulata. We compare the genetic variation of a small (Ne, 100) and relatively isolated upland population to that of its much larger (Ne approximately 2400) downstream counterpart. As predicted, microsatellite diversity in the upland population is significantly lower and highly differentiated from the population further downstream. Surprisingly, however, these guppy populations are not differentiated by MHC genetic variation and show very similar levels of allelic richness. Computer simulations indicate that the observed level of genetic variation can be maintained with overdominant selection acting at three DAB loci. The selection coefficients differ dramatically between the upland (s > or = 0.2) and lowland (s guppies in the upland habitat, which has resulted in high levels of MHC diversity being maintained in this population despite considerable genetic drift.

  14. Balancing selection and genetic drift create unusual patterns of MHCII variation in Galapagos mockingbirds

    Czech Academy of Sciences Publication Activity Database

    Vlček, Jakub; Hoeck, P. E. A.; Keller, L. F.; Wayhart, J. P.; Dolinová, I.; Štefka, Jan

    2016-01-01

    Roč. 25, č. 19 (2016), s. 4757-4772 ISSN 0962-1083 R&D Projects: GA ČR GPP506/12/P529 Institutional support: RVO:60077344 Keywords : major histocompatibility complex * Mimus * genetic diversity * population size * trans-species polymorphism Subject RIV: EG - Zoology Impact factor: 6.086, year: 2016

  15. Population genetics of drifting (Calanus spp.) and resident (Acartia clausi) plankton in Norwegian fjords

    Digital Repository Service at National Institute of Oceanography (India)

    Bucklin, A.; Kaartvedt, S.; Guarnieri, M.; Goswami, U.

    of Calanus co-occurred in significantly different proportions in the fjords. Based on a 350 base-pair region of mitochondrial 16S rRNA, Calanus spp. varied in molecular genetic diversity, with the highest values for C. helgolandicus. There was no evidence...

  16. Combining hydrodynamic modelling with genetics: can passive larval drift shape the genetic structure of Baltic Mytilus populations?

    Science.gov (United States)

    Stuckas, Heiko; Knöbel, Loreen; Schade, Hanna; Breusing, Corinna; Hinrichsen, Hans-Harald; Bartel, Manuela; Langguth, Klaudia; Melzner, Frank

    2017-05-01

    While secondary contact between Mytilus edulis and Mytilus trossulus in North America results in mosaic hybrid zone formation, both species form a hybrid swarm in the Baltic. Despite pervasive gene flow, Baltic Mytilus species maintain substantial genetic and phenotypic differentiation. Exploring mechanisms underlying the contrasting genetic composition in Baltic Mytilus species will allow insights into processes such as speciation or adaptation to extremely low salinity. Previous studies in the Baltic indicated that only weak interspecific reproductive barriers exist and discussed the putative role of adaptation to environmental conditions. Using a combination of hydrodynamic modelling and multilocus genotyping, we investigate how oceanographic conditions influence passive larval dispersal and hybrid swarm formation in the Baltic. By combining our analyses with previous knowledge, we show a genetic transition of Baltic Mytilus species along longitude 12°-13°E, that is a virtual line between Malmö (Sweden) and Stralsund (Germany). Although larval transport only occurs over short distances (10-30 km), limited larval dispersal could not explain the position of this genetic transition zone. Instead, the genetic transition zone is located at the area of maximum salinity change (15-10 psu). Thus, we argue that selection results in weak reproductive barriers and local adaptation. This scenario could maintain genetic and phenotypic differences between Baltic Mytilus species despite pervasive introgressive hybridization. © 2017 John Wiley & Sons Ltd.

  17. Genetic drift outweighs natural selection at toll-like receptor (TLR) immunity loci in a re-introduced population of a threatened species.

    Science.gov (United States)

    Grueber, Catherine E; Wallis, Graham P; Jamieson, Ian G

    2013-09-01

    During population establishment, genetic drift can be the key driver of changes in genetic diversity, particularly while the population is small. However, natural selection can also play a role in shaping diversity at functionally important loci. We used a well-studied, re-introduced population of the threatened Stewart Island robin (N = 722 pedigreed individuals) to determine whether selection shaped genetic diversity at innate immunity toll-like receptor (TLR) genes, over a 9-year period of population growth following establishment with 12 genetic founders. We found no evidence for selection operating with respect to TLR diversity on first-year overwinter survival for the majority of loci, genotypes and alleles studied. However, survival of individuals with TLR4BE genotype was significantly improved: these birds were less than half as likely to die prior to maturity compared with all other TLR4 genotypes. Furthermore, the population frequency of this genotype, at a two-fold excess over Hardy-Weinberg expectation, was increased by nonrandom mating. Near-complete sampling and full pedigree and reproductive data enabled us to eliminate other potential causes of these patterns including inbreeding, year effects, density dependence, selection on animals at earlier life history stages or genome-level association of the TLR4E allele with 'good genes'. However, comparison of observed levels of gene diversity to predictions under simulated genetic drift revealed results consistent with neutral expectations for all loci, including TLR4. Although selection favoured TLR4BE heterozygotes in this population, these effects were insufficient to outweigh genetic drift. This is the first empirical study to show that genetic drift can overwhelm natural selection in a wild population immediately following establishment. © 2013 John Wiley & Sons Ltd.

  18. Genetic drift. The real tiger mother: from the clinical geneticist's perspective.

    Science.gov (United States)

    Shur, Natasha

    2011-09-01

    The Battle Hymn of the Tiger Mother by Amy Chua raises questions about motherhood and what is admirable. Chua promotes strict, Old World, uncompromising values stressing academic performance above all, insisting on drilling and practice, and instilling respect for authority. As clinical geneticists, we meet an entirely different type of mother than Chua, the clinical genetics mother who fights illnesses, schools, hospital policies, and insurance companies. She battles not against her child but for her child. With brilliance and resilience, she creates a child-centered world. The stories of four clinical genetics mothers rally us to reject extreme parenting and appreciate the simple joys of childhood. Copyright © 2011 Wiley-Liss, Inc.

  19. Tempest in a tea pot: How did the public conversation on genetically modified crops drift so far from the facts?

    Science.gov (United States)

    Goldstein, Daniel A

    2014-06-01

    The debate over genetically modified (GM) crops has raged in Europe since 1996, but had barely risen above a whisper in the USA until recent labeling debates raised public attention. This article will explain GM crops and traits discuss safety assessment provide a view on safety from authoritative organizations discuss selected issues of current debate, and provide the author's perspective as to why the public debate has drifted so far from scientific reality. The economic and environmental benefits of GM crops are beyond scope, but references are provided. GM food and feed undergo comprehensive assessments using recognized approaches to assure they are as safe as the conventional congener. Issues of food safety and nutrition, unrelated to the GM process, may arise when GM foods display novel components or composition. Unanticipated genetic effects in GM crops appear to be limited in contrast to existing variations among conventional varieties resulting from breeding, mutation, and natural mobile genetic elements. Allergenic potential is assessed when selecting genes for introduction into GM crops and remains a theoretical risk to date. Emerging weed and insect resistance is not unique to GM technology and will require the use of integrated pest management/best practices for pest control. Gene flow from GM crops to wild relatives is limited by existing biological barriers but can at time be a relevant consideration in gene selection and planting practices. Insect-resistant GM crops have significantly reduced use of chemical insecticides and appear to have reduced the incidence of pesticide poisoning in areas where small scale farming and hand application are common. Changes in herbicide patterns are more complex and are evolving over time in response to weed resistance management needs. Recent public debate is driven by a combination of unfounded allegations about the technology and purveyors, pseudoscience, and attempts to apply a strict precautionary principle.

  20. Purifying selection and genetic drift shaped Pleistocene evolution of the mitochondrial genome in an endangered Australian freshwater fish.

    Science.gov (United States)

    Pavlova, A; Gan, H M; Lee, Y P; Austin, C M; Gilligan, D M; Lintermans, M; Sunnucks, P

    2017-05-01

    Genetic variation in mitochondrial genes could underlie metabolic adaptations because mitochondrially encoded proteins are directly involved in a pathway supplying energy to metabolism. Macquarie perch from river basins exposed to different climates differ in size and growth rate, suggesting potential presence of adaptive metabolic differences. We used complete mitochondrial genome sequences to build a phylogeny, estimate lineage divergence times and identify signatures of purifying and positive selection acting on mitochondrial genes for 25 Macquarie perch from three basins: Murray-Darling Basin (MDB), Hawkesbury-Nepean Basin (HNB) and Shoalhaven Basin (SB). Phylogenetic analysis resolved basin-level clades, supporting incipient speciation previously inferred from differentiation in allozymes, microsatellites and mitochondrial control region. The estimated time of lineage divergence suggested an early- to mid-Pleistocene split between SB and the common ancestor of HNB+MDB, followed by mid-to-late Pleistocene splitting between HNB and MDB. These divergence estimates are more recent than previous ones. Our analyses suggested that evolutionary drivers differed between inland MDB and coastal HNB. In the cooler and more climatically variable MDB, mitogenomes evolved under strong purifying selection, whereas in the warmer and more climatically stable HNB, purifying selection was relaxed. Evidence for relaxed selection in the HNB includes elevated transfer RNA and 16S ribosomal RNA polymorphism, presence of potentially mildly deleterious mutations and a codon (ATP6 113 ) displaying signatures of positive selection (ratio of nonsynonymous to synonymous substitution rates (dN/dS) >1, radical change of an amino-acid property and phylogenetic conservation across the Percichthyidae). In addition, the difference could be because of stronger genetic drift in the smaller and historically more subdivided HNB with low per-population effective population sizes.

  1. Gene flow and genetic drift contribute to high genetic diversity with low phylogeographical structure in European hoopoes (Upupa epops).

    Science.gov (United States)

    Wang, Erjia; Van Wijk, Rien E; Braun, Markus Santhosh; Wink, Michael

    2017-08-01

    The Hoopoe (Upupa epops epops) breeds widely in Eurasia and most populations migrate to Africa during the boreal winter. To date, data regarding its phylogeography in Europe are missing. In this study, we investigated the phylogeography and population genetics of Hoopoes by means of mitochondrial DNA (mtDNA) sequencing as well as microsatellite genotyping. Our analyses revealed 32 haplotypes in the cytochrome c oxidase subunit I (COI) (269 individuals) and 50 haplotypes in cytochrome b (cyt b) (233 individuals). Analyses of mtDNA clearly demonstrated that the bulk of variance (98.23%) could be attributed to inner-population variance. Thus, the low frequency single nucleotide substitutions resulted in "star-like" haplotype networks without define geographical structure. Hoopoes clearly experienced a bottleneck followed by sudden expansion, as was also apparent from tests on the unimodal mismatch, Bayesian skyline plot, significant negative neutrality tests as well as bottleneck signals. These tests pointed to strong demographic fluctuations in the hoopoe populations. GENELAND, DAPC and STRUCTURE analyses of microsatellites along with their corresponding Fst values suggested that current genetic restriction separates birds from Armenia from the remaining populations. Except for hoopoes from Armenia, all the European populations exhibited an admixed phylogeographic pattern. We conclude that this genetic panmixia might be a consequence of a combination of historical events (e.g. repeated colonizations and retreatments from northern habitats during the Pleistocene and a sudden postglacial expansion) and current processes (e.g. long-distance migration, immigration or population recruitments). Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Exact Markov chain and approximate diffusion solution for haploid genetic drift with one-way mutation.

    Science.gov (United States)

    Hössjer, Ola; Tyvand, Peder A; Miloh, Touvia

    2016-02-01

    The classical Kimura solution of the diffusion equation is investigated for a haploid random mating (Wright-Fisher) model, with one-way mutations and initial-value specified by the founder population. The validity of the transient diffusion solution is checked by exact Markov chain computations, using a Jordan decomposition of the transition matrix. The conclusion is that the one-way diffusion model mostly works well, although the rate of convergence depends on the initial allele frequency and the mutation rate. The diffusion approximation is poor for mutation rates so low that the non-fixation boundary is regular. When this happens we perturb the diffusion solution around the non-fixation boundary and obtain a more accurate approximation that takes quasi-fixation of the mutant allele into account. The main application is to quantify how fast a specific genetic variant of the infinite alleles model is lost. We also discuss extensions of the quasi-fixation approach to other models with small mutation rates. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Addressing the Externalities from Genetically Modified Pollen Drift on a Heterogeneous Landscape

    Directory of Open Access Journals (Sweden)

    Mattia C. Mancini

    2016-10-01

    Full Text Available Genetically modified (GM crops have single or multiple genes introduced to obtain crop characteristics that cannot be obtained through conventional breeding. Pollen mediated gene flow from GM to non-GM crops causes some crops planted as non-GM to become GM, and this imposes economic losses on farmers who planted a non-GM crop but then have to sell the harvest on a GM market. The economic losses that result when both crops are grown together depend on the institutional arrangements and the type of property rights in place. We analyze how the spatial heterogeneity of a farmer’s fields affects the land allocation between buffers, the GM, and the non-GM crop based on cross-pollination and initial assignment of property rights. Greater spatial heterogeneity reduces the possibility of coexistence of crops on the landscape and increases the economic losses. Buffer zones enforced to reduce cross-pollination result in less coexistence on heterogeneous landscapes.

  4. Genetic and antigenic drift of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in a closed population evaluated by full genome sequencing

    DEFF Research Database (Denmark)

    Kvisgaard, Lise Kirstine; Hjulsager, Charlotte Kristiane; Larsen, Lars Erik

    of circulating PRRS viruses in Danish pigs and to investigate the genetic drift of the virus in a closed population with very limited introductions of new animals. The study included phylogenetic analysis of full genome sequences of eight Type 1 and nine Type 2 PRRS viruses, including the very first Danish......Porcine Reproductive and Respiratory Syndrome (PRRS) viruses are divided into two major genotypes (Type 1 and Type 2) based on their genetic diversity. Type 1 PRRSV is further divided into at least 3 subtypes, but until now only subtype 1 has been detected in Western Europe and North America. Both...... isolated Type 1 virus and the very first Danish Type 2 PRRS virus isolated from a non-vaccinated pig herd. Furthermore, by sequencing ORF5 and ORF7 of 43 Type 1 and 57 Type 2 viruses isolated between 2003 and 2013, the level of genetic diversity was assessed. The results showed a very high genetic...

  5. Changes in genetically drifted H3N2 influenza A viruses and vaccine effectiveness in adults 65 years and older during the 2016/17 season in Denmark

    DEFF Research Database (Denmark)

    Trebbien, Ramona; Fischer, Thea K; Krause, Tyra Grove

    2017-01-01

    BACKGROUND: In Denmark, influenza A virus of the subtype H3N2 has been dominating the 2016/17 season, as in most countries of the Northern Hemisphere. OBJECTIVES: This study was conducted as part of the Danish seasonal influenza surveillance programme to genetically characterize circulating H3N2...... viruses and determine the seasonal vaccine effectiveness (VE) overall in the Danish population and further on the virus cluster level. STUDY DESIGN: Influenza virus positive samples submitted for the national surveillance programme were genetically characterized by sequencing. VE estimates against...... influenza A and the circulating virus clusters were determined in patients above 65 years using the test-negative case-control design. RESULTS: The genetic characterization revealed several genetically drifted viruses, which could be divided into four main clusters by the defining amino acid substitutions...

  6. Time-Sampled Population Sequencing Reveals the Interplay of Selection and Genetic Drift in Experimental Evolution ofPotato Virus Y.

    Science.gov (United States)

    Kutnjak, Denis; Elena, Santiago F; Ravnikar, Maja

    2017-08-15

    RNA viruses are one of the fastest-evolving biological entities. Within their hosts, they exist as genetically diverse populations (i.e., viral mutant swarms), which are sculpted by different evolutionary mechanisms, such as mutation, natural selection, and genetic drift, and also the interactions between genetic variants within the mutant swarms. To elucidate the mechanisms that modulate the population diversity of an important plant-pathogenic virus, we performed evolution experiments with Potato virus Y (PVY) in potato genotypes that differ in their defense response against the virus. Using deep sequencing of small RNAs, we followed the temporal dynamics of standing and newly generated variations in the evolving viral lineages. A time-sampled approach allowed us to (i) reconstruct theoretical haplotypes in the starting population by using clustering of single nucleotide polymorphisms' trajectories and (ii) use quantitative population genetics approaches to estimate the contribution of selection and genetic drift, and their interplay, to the evolution of the virus. We detected imprints of strong selective sweeps and narrow genetic bottlenecks, followed by the shift in frequency of selected haplotypes. Comparison of patterns of viral evolution in differently susceptible host genotypes indicated possible diversifying evolution of PVY in the less-susceptible host (efficient in the accumulation of salicylic acid). IMPORTANCE High diversity of within-host populations of RNA viruses is an important aspect of their biology, since they represent a reservoir of genetic variants, which can enable quick adaptation of viruses to a changing environment. This study focuses on an important plant virus, Potato virus Y , and describes, at high resolution, temporal changes in the structure of viral populations within different potato genotypes. A novel and easy-to-implement computational approach was established to cluster single nucleotide polymorphisms into viral haplotypes from

  7. Genetic drift vs. natural selection in a long-term small isolated population: major histocompatibility complex class II variation in the Gulf of California endemic porpoise (Phocoena sinus).

    Science.gov (United States)

    Munguia-Vega, Adrian; Esquer-Garrigos, Yareli; Rojas-Bracho, Lorenzo; Vazquez-Juarez, Ricardo; Castro-Prieto, Aines; Flores-Ramirez, Sergio

    2007-10-01

    Although many studies confirm long-term small isolated populations (e.g. island endemics) commonly sustain low neutral genetic variation as a result of genetic drift, it is less clear how selection on adaptive or detrimental genes interplay with random forces. We investigated sequence variation at two major histocompatibility complex (Mhc) class II loci on a porpoise endemic to the upper Gulf of California, México (Phocoena sinus, or vaquita). Its unique declining population is estimated around 500 individuals. Single-strand conformation polymorphism analysis revealed one putative functional allele fixed at the locus DQB (n = 25). At the DRB locus, we found two presumed functional alleles (n = 29), differing by a single nonsynonymous nucleotide substitution that could increase the stability at the dimer interface of alphabeta-heterodimers on heterozygous individuals. Identical trans-specific DQB1 and DRB1 alleles were identified between P. sinus and its closest relative, the Burmeister's porpoise (Phocoena spinipinnis). Comparison with studies on four island endemic mammals suggests fixation of one allele, due to genetic drift, commonly occurs at the DQA or DQB loci (effectively neutral). Similarly, deleterious alleles of small effect are also effectively neutral and can become fixed; a high frequency of anatomical malformations on vaquita gave empirical support to this prediction. In contrast, retention of low but functional polymorphism at the DRB locus was consistent with higher selection intensity. These observations indicated natural selection could maintain (and likely also purge) some crucial alleles even in the face of strong and prolonged genetic drift and inbreeding, suggesting long-term small populations should display low inbreeding depression. Low levels of Mhc variation warn about a high susceptibility to novel pathogens and diseases in vaquita.

  8. Stokes drift

    Science.gov (United States)

    van den Bremer, T. S.; Breivik, Ø.

    2017-12-01

    During its periodic motion, a particle floating at the free surface of a water wave experiences a net drift velocity in the direction of wave propagation, known as the Stokes drift (Stokes 1847 Trans. Camb. Philos. Soc. 8, 441-455). More generally, the Stokes drift velocity is the difference between the average Lagrangian flow velocity of a fluid parcel and the average Eulerian flow velocity of the fluid. This paper reviews progress in fundamental and applied research on the induced mean flow associated with surface gravity waves since the first description of the Stokes drift, now 170 years ago. After briefly reviewing the fundamental physical processes, most of which have been established for decades, the review addresses progress in laboratory and field observations of the Stokes drift. Despite more than a century of experimental studies, laboratory studies of the mean circulation set up by waves in a laboratory flume remain somewhat contentious. In the field, rapid advances are expected due to increasingly small and cheap sensors and transmitters, making widespread use of small surface-following drifters possible. We also discuss remote sensing of the Stokes drift from high-frequency radar. Finally, the paper discusses the three main areas of application of the Stokes drift: in the coastal zone, in Eulerian models of the upper ocean layer and in the modelling of tracer transport, such as oil and plastic pollution. Future climate models will probably involve full coupling of ocean and atmosphere systems, in which the wave model provides consistent forcing on the ocean surface boundary layer. Together with the advent of new space-borne instruments that can measure surface Stokes drift, such models hold the promise of quantifying the impact of wave effects on the global atmosphere-ocean system and hopefully contribute to improved climate projections. This article is part of the theme issue 'Nonlinear water waves'.

  9. Genetic drift and selection effects of modified recurrent full-sib selection programs in two F2 populations of European flint maize.

    Science.gov (United States)

    Flachenecker, C; Frisch, M; Falke, K C; Melchinger, A E

    2006-10-01

    Selection response of a modified recurrent full-sib (FS) selection scheme conducted in two European flint F(2) maize (Zea mays L.) populations was re-evaluated. Our objectives were to (1) determine the selection response for per se and testcross performance in both populations and (2) separate genetic effects due to selection from those due to random genetic drift. Modified recurrent FS selection was conducted at three locations using an effective population size N(e) = 32 and a selection rate of 25% for a selection index, based on grain yield and grain moisture. Recombination was performed according to a pseudo-factorial mating scheme. Selection response was assessed using a population diallel including the source population and advanced selection cycles, as well as testcrosses with unrelated inbred line testers and the parental F(1) generation. Selection response per cycle was significant for grain yield and grain moisture in both populations. Effects of random genetic drift caused only a small reduction in the selection response. No significant selection response was observed for testcrosses, suggesting that for heterotic traits, such as grain yield, a high frequency of favorable alleles in the elite tester masked the effects of genes segregating in the populations. We conclude that our modified recurrent FS selection is an alternative to other commonly applied intrapopulation recurrent selection schemes, and some of its features may also be useful for increasing the efficiency of interpopulation recurrent selection programs.

  10. Influence of Genetic Drift of Restoring Gene (Rf on Seed Purity of Yuetai A, a Honglian-Type Cytoplasmic Male Sterile Line in Hybrid Rice

    Directory of Open Access Journals (Sweden)

    Ji-feng Wang

    2008-06-01

    Full Text Available The seed samples of Yuetai A, a Honglian (HL type cytoplasmic male sterile (CMS line in hybrid rice were investigated to assess the seed purity and to analyze the cause of off-type plants by imitating the biological contaminant to Yuetai A in Nanjing, Jiangsu Province and Lingshui, Hainan Province during 2004–2006. The seed impurity of Yuetai A mainly resulted from the genetic drift of restoring fertility gene (Rf after biological contamination but not from its sterility unstability. All of the ten maintainer lines, five restorer lines and three thermo-sensitive genic male sterile lines used in the study could pollinate Yuetai A and Yuetai B to produce F1 plants, directly or indirectly resulting in Rf-gene drifting into Yuetai A and generating ‘iso-cytoplasm restoring-generations’. Furthermore, high outcrossing rate and similar heading date of Yuetai A with many varieties used in rice production might easily result in the biological contamination. After removing all plants with Rf-gene mixed in Yuetai A and preventing Rf-gene drifting into Yuetai A, the seed purity of Yuetai A and Yuetai B had been raised to 100%.

  11. Reducing Pesticide Drift

    Science.gov (United States)

    Provides information about pesticide spray drift, including problems associated with drift, managing risks from drift and the voluntary Drift Reduction Technology program that seeks to reduce spray drift through improved spray equipment design.

  12. Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity.

    Directory of Open Access Journals (Sweden)

    Stephen R Doyle

    2017-07-01

    drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations.

  13. The Effects of Both Recent and Long-Term Selection and Genetic Drift Are Readily Evident in North American Barley Breeding Populations

    Directory of Open Access Journals (Sweden)

    Ana M. Poets

    2016-03-01

    Full Text Available Barley was introduced to North America ∼400 yr ago but adaptation to modern production environments is more recent. Comparisons of allele frequencies among growth habits and spike (inflorescence types in North America indicate that significant genetic differentiation has accumulated in a relatively short evolutionary time span. Allele frequency differentiation is greatest among barley with two-row vs. six-row spikes, followed by spring vs. winter growth habit. Large changes in allele frequency among breeding programs suggest a major contribution of genetic drift and linked selection on genetic variation. Despite this, comparisons of 3613 modern North American cultivated barley breeding lines that differ for spike-type and growth habit permit the discovery of 142 single nucleotide polymorphism (SNP outliers putatively linked to targets of selection. For example, SNPs within the Cbf4, Ppd-H1, and Vrn-H1 loci, which have previously been associated with agronomically adaptive phenotypes, are identified as outliers. Analysis of extended haplotype sharing identifies genomic regions shared within and among breeding populations, suggestive of a number of genomic regions subject to recent selection. Finally, we are able to identify recent bouts of gene flow between breeding populations that could point to the sharing of agronomically adaptive variation. These results are supported by pedigrees and breeders’ understanding of germplasm sharing.

  14. Ultra-low mass drift chambers

    International Nuclear Information System (INIS)

    Assiro, R.; Cappelli, L.; Cascella, M.; De Lorenzis, L.; Grancagnolo, F.; Ignatov, F.; L'Erario, A.; Maffezzoli, A.; Miccoli, A.; Onorato, G.; Perillo, M.; Piacentino, G.; Rella, S.; Rossetti, F.; Spedicato, M.; Tassielli, G.

    2013-01-01

    We present a novel low mass drift chamber concept, developed in order to fulfill the stringent requirements imposed by the experiments for extremely rare processes, which require high resolutions (order of 100–200 keV/c) for particle momenta in a range (50–100 MeV/c) totally dominated by the multiple scattering contribution. We describe a geometry optimization procedure and a new wiring strategy with a feed-through-less wire anchoring system developed and tested on a drift chamber prototype under completion at INFN-Lecce

  15. The effect of increasingly stringent diagnostic criteria on sex ...

    African Journals Online (AJOL)

    Sex differences in premorbid function and symptomatology were examined as increasingly stringent criteria for schizophrenia were applied to 182 male and 139 female . psychotic patients. The male/female ratio rose from 1.6 among those meeting the CATEGO 'broad' criteria for schizophrenia to 3.7 among those satisfying ...

  16. Can small wildlife conservancies maintain genetically stable populations of large mammals? Evidence for increased genetic drift in geographically restricted populations of Cape buffalo in East Africa

    DEFF Research Database (Denmark)

    Heller, R; Okello, J B A; Siegismund, H

    2010-01-01

    populations, the level of genetic differentiation found here is comparable to that among pan-African populations. Overall, correlations between conservancy area and indices of genetic diversity suggest buffalo populations inhabiting small parks are showing signs of genetic erosion, stressing the need for more......The Cape buffalo (Syncerus caffer caffer) is one of the dominant and most widespread herbivores in sub-Saharan Africa. High levels of genetic diversity and exceptionally low levels of population differentiation have been found in the Cape buffalo compared to other African savannah ungulates...... active management of such populations. Our findings raise concerns about the future of other African savannah ungulates with lower population sizes and inferior dispersal capabilities compared with the buffalo....

  17. Circuitry linking the Csr and stringent response global regulatory systems.

    Science.gov (United States)

    Edwards, Adrianne N; Patterson-Fortin, Laura M; Vakulskas, Christopher A; Mercante, Jeffrey W; Potrykus, Katarzyna; Vinella, Daniel; Camacho, Martha I; Fields, Joshua A; Thompson, Stuart A; Georgellis, Dimitris; Cashel, Michael; Babitzke, Paul; Romeo, Tony

    2011-06-01

    CsrA protein regulates important cellular processes by binding to target mRNAs and altering their translation and/or stability. In Escherichia coli, CsrA binds to sRNAs, CsrB and CsrC, which sequester CsrA and antagonize its activity. Here, mRNAs for relA, spoT and dksA of the stringent response system were found among 721 different transcripts that copurified with CsrA. Many of the transcripts that copurified with CsrA were previously determined to respond to ppGpp and/or DksA. We examined multiple regulatory interactions between the Csr and stringent response systems. Most importantly, DksA and ppGpp robustly activated csrB/C transcription (10-fold), while they modestly activated csrA expression. We propose that CsrA-mediated regulation is relieved during the stringent response. Gel shift assays confirmed high affinity binding of CsrA to relA mRNA leader and weaker interactions with dksA and spoT. Reporter fusions, qRT-PCR and immunoblotting showed that CsrA repressed relA expression, and (p)ppGpp accumulation during stringent response was enhanced in a csrA mutant. CsrA had modest to negligible effects on dksA and spoT expression. Transcription of dksA was negatively autoregulated via a feedback loop that tended to mask CsrA effects. We propose that the Csr system fine-tunes the stringent response and discuss biological implications of the composite circuitry. © Published 2011. This article is a US Government work and is in the public domain in the USA.

  18. Evidence of genetic drift and reassortment in infectious bursal disease virus and emergence of outbreaks in poultry farms in India.

    Science.gov (United States)

    Patel, Amrutlal K; Pandey, Vinod C; Pal, Joy K

    2016-06-01

    Recurrent outbreaks of infectious bursal disease (IBD) have become a burning problem to the poultry industry worldwide. Here, we performed genetic analysis of IBD virus (IBDV) field isolates from recent outbreaks in various poultry farms in India. The sequence analysis of IBDV VP2 hypervariable region revealed amino acid pattern similar to that of very virulent (222A, 242I, 253Q, 256I, 272I, 279D, 284A, 294I, 299S and 330S) and intermediate plus virulent (222A, 242I, 253Q, 256I, 272T, 279N, 284A, 294I, 299S and 330S) type whereas analysis of VP1 revealed presence of sequence similar to that of very virulent (61I, 145T) and unique (61I, 141I, 143D, 145S) type in field isolates. Among the eight field isolates, two isolates contained very virulent type VP2 and unique type VP1, three contained intermediate plus virulent type VP2 and unique type VP1 whereas five contained both VP2 and VP1 of very virulent type. The phylogenetic analysis based on VP2 nucleotide sequence showed clustering of all eight isolates close to known very virulent strains whereas based on VP1, five isolates formed unique cluster and three isolates were placed close to very virulent strains. The isolates forming unique VP1 cluster showed highest similarity with classical virulent IBDVs suggesting their possible evolution from segment B of non-very virulent IBDVs. Interestingly, these five isolates were responsible for outbreaks in four different farms located at three different geographic locations in India. These observations indicates genetic reassortment between segment A and segment B from co-infecting IBDV strains leading to emergence of very virulent strains and their widespread prevalence in Indian poultry farms. The presence of 272I and 279D in VP2 protein of five field isolates may explain possible cause of Gumboro intermediate plus vaccine failure in prevention of the outbreaks. However, mortality caused by other three strains which are antigenically similar to VP1 of intermediate plus

  19. Analyses of historical and current populations of black grouse in Central Europe reveal strong effects of genetic drift and loss of genetic diversity

    NARCIS (Netherlands)

    Segelbacher, G.; Strand, T.M.; Quintela, M.; Axelsson, T.; Jansman, H.A.H.; Koelewijn, H.P.; Hoglund, J.

    2014-01-01

    Black grouse (Tetrao tetrix) in Central Europe have undergone a severe contraction of their range in recent decades with only a few small isolated remaining populations. Here we compare genetic diversity of two contemporary isolated populations (Sallandse Heuvelrug, Netherlands and Luneburger Heide,

  20. Is ionizing radiation regulated more stringently than chemical carcinogens

    International Nuclear Information System (INIS)

    Travis, C.C.; Pack, S.R.; Hattemer-Frey, H.A.

    1989-01-01

    It is widely believed that United States government agencies regulate exposure to ionizing radiation more stringently than exposure to chemical carcinogens. It is difficult to verify this perception, however, because chemical carcinogens and ionizing radiation are regulated using vastly different strategies. Chemical carcinogens are generally regulated individually. Regulators consider the risk of exposure to one chemical rather than the cumulative radiation exposure from all sources. Moreover, standards for chemical carcinogens are generally set in terms of quantities released or resultant environmental concentrations, while standards for ionizing radiation are set in terms of dose to the human body. Since chemicals and ionizing radiation cannot be compared on the basis of equal dose to the exposed individual, standards regulating chemicals and ionizing radiation cannot be compared directly. It is feasible, however, to compare the two sets of standards on the basis of equal risk to the exposed individual, assuming that standards for chemicals and ionizing radiation are equivalent if estimated risk levels are equitable. This paper compares risk levels associated with current standards for ionizing radiation and chemical carcinogens. The authors do not attempt to determine whether either type of risk is regulated too stringently or not stringently enough but endeavor only to ascertain if ionizing radiation is actually regulated more strictly than chemical carcinogens

  1. Simultaneous Estimation of Mixing Rates and Genetic Drift Under Successive Sampling of Genetic Markers With Application to the Mud Crab (Scylla paramamosain) in Japan

    OpenAIRE

    Kitakado, Toshihide; Kitada, Shuichi; Obata, Yasuhiro; Kishino, Hirohisa

    2006-01-01

    In stock enhancement programs, it is important to assess mixing rates of released individuals in stocks. For this purpose, genetic stock identification has been applied. The allele frequencies in a composite population are expressed as a mixture of the allele frequencies in the natural and released populations. The estimation of mixing rates is possible, under successive sampling from the composite population, on the basis of temporal changes in allele frequencies. The allele frequencies in t...

  2. Drift chamber detectors

    International Nuclear Information System (INIS)

    Duran, I.; Martinez Laso, L.

    1989-01-01

    A review of High Energy Physics detectors based on drift chambers is presented. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysied, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author)

  3. Drift Chambers detectors

    International Nuclear Information System (INIS)

    Duran, I.; Martinez laso, L.

    1989-01-01

    We present here a review of High Energy Physics detectors based on drift chambers. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysed, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author) 115 refs

  4. Flight Hardware Packaging Design for Stringent EMC Radiated Emission Requirements

    Science.gov (United States)

    Lortz, Charlene L.; Huang, Chi-Chien N.; Ravich, Joshua A.; Steiner, Carl N.

    2013-01-01

    This packaging design approach can help heritage hardware meet a flight project's stringent EMC radiated emissions requirement. The approach requires only minor modifications to a hardware's chassis and mainly concentrates on its connector interfaces. The solution is to raise the surface area where the connector is mounted by a few millimeters using a pedestal, and then wrapping with conductive tape from the cable backshell down to the surface-mounted connector. This design approach has been applied to JPL flight project subsystems. The EMC radiated emissions requirements for flight projects can vary from benign to mission critical. If the project's EMC requirements are stringent, the best approach to meet EMC requirements would be to design an EMC control program for the project early on and implement EMC design techniques starting with the circuit board layout. This is the ideal scenario for hardware that is built from scratch. Implementation of EMC radiated emissions mitigation techniques can mature as the design progresses, with minimal impact to the design cycle. The real challenge exists for hardware that is planned to be flown following a built-to-print approach, in which heritage hardware from a past project with a different set of requirements is expected to perform satisfactorily for a new project. With acceptance of heritage, the design would already be established (circuit board layout and components have already been pre-determined), and hence any radiated emissions mitigation techniques would only be applicable at the packaging level. The key is to take a heritage design with its known radiated emissions spectrum and repackage, or modify its chassis design so that it would have a better chance of meeting the new project s radiated emissions requirements.

  5. Comparison of urine iodine/creatinine ratio between patients following stringent and less stringent low iodine diet for radioiodine remnant ablation of thyroid cancer

    International Nuclear Information System (INIS)

    Roh, Jee Ho; Kim, Byung Il; Ha, Ji Su; Chang, Sei Joong; Shin, Hye Young; Choi, Joon Hyuk; Kim, Do Min; Kim, Chong Soon

    2006-01-01

    A low iodine diet (LID) for 1 ∼ 2 weeks is recommended for patients who undergoing radioiodine remnant ablation. However, the LID educations for patients are different among centers because there is no concrete recommendation for protocol of LID. In this investigation, we compared two representative types of LID protocols performed in several centers in Korea using urine iodine to creatinine tatio (urine I/Cr). From 2006, April to June, patients referred to our center for radioiodine remnant ablation of thyroid cancer from several local hospitals which had different LID protocols were included. We divided into two groups, stringent LID for 1 week and less stringent LID for 2 weeks, then measured their urine I/Cr ratio with spot urine when patients were admitted to the hospital. Total 27 patients were included in this investigation (M:F = 1:26; 13 in one-week stringent LID; 14 in two-week less stringent LID). Average of urine I/Cr ratio was 127.87 ± 78.52 μ g/g in stringent LID for 1 week, and 289.75 ± 188.24 μ g/g in less stringent LID for 2 weeks. It was significantly lower in stringent LID for 1 week group (ρ = 0.008). The number of patients whose urine I/Cr ratios were below 100 μ g/g was 6 of 13 in stringent LID for 1 week group, and 3 of 14 in less stringent LID for 2 weeks group. Stringent LID for 1 week resulted in better urinary I/Cr ratio in our investigation compared with the other protocol. However it still resulted in plenty of inadequate range of I/Cr ratio, so more stringent protocol such as stringent LID for 2 weeks is expected more desirable

  6. Dike/Drift Interactions

    International Nuclear Information System (INIS)

    Gaffiney, E.

    2004-01-01

    This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1)

  7. Dike/Drift Interactions

    Energy Technology Data Exchange (ETDEWEB)

    E. Gaffiney

    2004-11-23

    This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1).

  8. The Drift Burst Hypothesis

    OpenAIRE

    Christensen, Kim; Oomen, Roel; Renò, Roberto

    2016-01-01

    The Drift Burst Hypothesis postulates the existence of short-lived locally explosive trends in the price paths of financial assets. The recent US equity and Treasury flash crashes can be viewed as two high profile manifestations of such dynamics, but we argue that drift bursts of varying magnitude are an expected and regular occurrence in financial markets that can arise through established mechanisms such as feedback trading. At a theoretical level, we show how to build drift bursts into the...

  9. Dike/Drift Interactions

    Energy Technology Data Exchange (ETDEWEB)

    E.S. Gaffney

    2003-10-08

    This report documents the model of events associated with a potential intrusion of magma from a volcanic dike into a drift or drifts in the Yucca Mountain Nuclear Waste Repository. The following topics are included in this report: (1) A discussion of dike propagation, which provides the basis for describing the path that a representative dike, or swarm of dikes, would follow during an event. (2) A discussion of magma flow, which evaluates the interaction at the junction of the propagating dike with the drift and the movement of magmatic products into and down drifts and, potentially, through a drift to the surface by way of access drift or a secondary dike opened up along the drift. (3) A discussion of gas flow and conductive cooling of a magma-filled drift, describing how an adjacent drift that has not been intersected by a dike could be affected by post-intrusion phenomena. Note that a gas flow analysis is also addressed in ''Igneous Intrusion Impacts on Waste Form and Waste Packages'' (BSC 2003 [DIRS 161810]), and those results are consistent with the results presented in this report.

  10. Role of the Stringent Stress Response in the Antibiotic Resistance Phenotype of Methicillin-Resistant Staphylococcus aureus.

    Science.gov (United States)

    Aedo, Sandra; Tomasz, Alexander

    2016-04-01

    Resistance to beta-lactam antibiotics in methicillin-resistantStaphylococcus aureus(MRSA) requires the presence of an acquired genetic determinant,mecAormecC, which encode penicillin-binding protein PBP2A or PBP2A', respectively. Although all MRSA strains share a mechanism of resistance, the phenotypic expression of beta-lactam resistance shows considerable strain-to-strain variation. The stringent stress response, a stress response that results from nutrient limitation, was shown to play a key role in determining the resistance level of an MRSA strain. In the present study, we validated the impact of the stringent stress response on transcription and translation ofmecAin the MRSA clinical isolate strain N315, which also carries known regulatory genes (mecI/mecR1/mecR2andblaI/blaR1) formecAtranscription. We showed that the impact of the stringent stress response on the resistance level may be restricted to beta-lactam resistance based on a "foreign" determinant such asmecA, as opposed to resistance based on mutations in the nativeS. aureusdeterminantpbpB(encoding PBP2). Our observations demonstrate that high-level resistance mediated by the stringent stress response follows the current model of beta-lactam resistance in which the native PBP2 protein is also essential for expression of the resistance phenotype. We also show that theStaphylococcus sciuri pbpDgene (also calledmecAI), the putative evolutionary precursor ofmecA, confers oxacillin resistance in anS. aureusstrain, generating a heterogeneous phenotype that can be converted to high and homogenous resistance by induction of the stringent stress response in the bacteria. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  11. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dwayne C. Kicker

    2001-09-28

    A statistical description of the probable block sizes formed by fractures around the emplacement drifts has been developed for each of the lithologic units of the repository host horizon. A range of drift orientations with the drift azimuth varied in 15{sup o} increments has been considered in the static analysis. For the quasi-static seismic analysis, and the time-dependent and thermal effects analysis, two drift orientations have been considered: a drift azimuth of 105{sup o} and the current emplacement drift azimuth of 75{sup o}. The change in drift profile resulting from progressive deterioration of the emplacement drifts has been assessed both with and without backfill. Drift profiles have been determined for four different time increments, including static (i.e., upon excavation), 200 years, 2,000 years, and 10,000 years. The effect of seismic events on rock fall has been analyzed. Block size distributions and drift profiles have been determined for three seismic levels, including a 1,000-year event, a 5,000-year event, and a 10,000-year event. Data developed in this modeling and analysis activity have been entered into the TDMS (DTN: MO0109RDDAAMRR.003). The following conclusions have resulted from this drift degradation analysis: (1) The available fracture data are suitable for supporting a detailed key block analysis of the repository host horizon rock mass. The available data from the north-south Main Drift and the east-west Cross Drift provide a sufficient representative fracture sample of the repository emplacement drift horizon. However, the Tptpln fracture data are only available from a relatively small section of the Cross Drift, resulting in a smaller fracture sample size compared to the other lithologic units. This results in a lower degree of confidence that the key block data based on the Tptpln data set is actually representative of the overall Tptpln key block population. (2) The seismic effect on the rock fall size distribution for all events

  12. Bulk development and stringent selection of microsatellite markers in the western flower thrips Frankliniella occidentalis.

    Science.gov (United States)

    Cao, Li-Jun; Li, Ze-Min; Wang, Ze-Hua; Zhu, Liang; Gong, Ya-Jun; Chen, Min; Wei, Shu-Jun

    2016-05-20

    Recent improvements in next-generation sequencing technologies have enabled investigation of microsatellites on a genome-wide scale. Faced with a huge amount of candidates, the use of appropriate marker selection criteria is crucial. Here, we used the western flower thrips Frankliniella occidentalis for an empirical microsatellite survey and validation; 132,251 candidate microsatellites were identified, 92,102 of which were perfect. Dinucleotides were the most abundant category, while (AG)n was the most abundant motif. Sixty primer pairs were designed and validated in two natural populations, of which 30 loci were polymorphic, stable, and repeatable, but not all in Hardy-Weinberg equilibrium (HWE) and linkage equilibrium. Four marker panels were constructed to understand effect of marker selection on population genetic analyses: (i) only accept loci with single nucleotide insertions (SNI); (ii) only accept the most polymorphic loci (MP); (iii) only accept loci that did not deviate from HWE, did not show SNIs, and had unambiguous peaks (SS) and (iv) all developed markers (ALL). Although the MP panel resulted in microsatellites of highest genetic diversity followed by the SNI, the SS performed best in individual assignment. Our study proposes stringent criteria for selection of microsatellites from a large-scale number of genomic candidates for population genetic studies.

  13. Modeling concept drift

    DEFF Research Database (Denmark)

    Borchani, Hanen; Martinez, Ana Maria; Masegosa, Andrés R.

    2015-01-01

    An often used approach for detecting and adapting to concept drift when doing classification is to treat the data as i.i.d. and use changes in classification accuracy as an indication of concept drift. In this paper, we take a different perspective and propose a framework, based on probabilistic...

  14. Abstraction of Drift Seepage

    Energy Technology Data Exchange (ETDEWEB)

    J.T. Birkholzer

    2004-11-01

    This model report documents the abstraction of drift seepage, conducted to provide seepage-relevant parameters and their probability distributions for use in Total System Performance Assessment for License Application (TSPA-LA). Drift seepage refers to the flow of liquid water into waste emplacement drifts. Water that seeps into drifts may contact waste packages and potentially mobilize radionuclides, and may result in advective transport of radionuclides through breached waste packages [''Risk Information to Support Prioritization of Performance Assessment Models'' (BSC 2003 [DIRS 168796], Section 3.3.2)]. The unsaturated rock layers overlying and hosting the repository form a natural barrier that reduces the amount of water entering emplacement drifts by natural subsurface processes. For example, drift seepage is limited by the capillary barrier forming at the drift crown, which decreases or even eliminates water flow from the unsaturated fractured rock into the drift. During the first few hundred years after waste emplacement, when above-boiling rock temperatures will develop as a result of heat generated by the decay of the radioactive waste, vaporization of percolation water is an additional factor limiting seepage. Estimating the effectiveness of these natural barrier capabilities and predicting the amount of seepage into drifts is an important aspect of assessing the performance of the repository. The TSPA-LA therefore includes a seepage component that calculates the amount of seepage into drifts [''Total System Performance Assessment (TSPA) Model/Analysis for the License Application'' (BSC 2004 [DIRS 168504], Section 6.3.3.1)]. The TSPA-LA calculation is performed with a probabilistic approach that accounts for the spatial and temporal variability and inherent uncertainty of seepage-relevant properties and processes. Results are used for subsequent TSPA-LA components that may handle, for example, waste package

  15. Abstraction of Drift Seepage

    International Nuclear Information System (INIS)

    J.T. Birkholzer

    2004-01-01

    This model report documents the abstraction of drift seepage, conducted to provide seepage-relevant parameters and their probability distributions for use in Total System Performance Assessment for License Application (TSPA-LA). Drift seepage refers to the flow of liquid water into waste emplacement drifts. Water that seeps into drifts may contact waste packages and potentially mobilize radionuclides, and may result in advective transport of radionuclides through breached waste packages [''Risk Information to Support Prioritization of Performance Assessment Models'' (BSC 2003 [DIRS 168796], Section 3.3.2)]. The unsaturated rock layers overlying and hosting the repository form a natural barrier that reduces the amount of water entering emplacement drifts by natural subsurface processes. For example, drift seepage is limited by the capillary barrier forming at the drift crown, which decreases or even eliminates water flow from the unsaturated fractured rock into the drift. During the first few hundred years after waste emplacement, when above-boiling rock temperatures will develop as a result of heat generated by the decay of the radioactive waste, vaporization of percolation water is an additional factor limiting seepage. Estimating the effectiveness of these natural barrier capabilities and predicting the amount of seepage into drifts is an important aspect of assessing the performance of the repository. The TSPA-LA therefore includes a seepage component that calculates the amount of seepage into drifts [''Total System Performance Assessment (TSPA) Model/Analysis for the License Application'' (BSC 2004 [DIRS 168504], Section 6.3.3.1)]. The TSPA-LA calculation is performed with a probabilistic approach that accounts for the spatial and temporal variability and inherent uncertainty of seepage-relevant properties and processes. Results are used for subsequent TSPA-LA components that may handle, for example, waste package corrosion or radionuclide transport

  16. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    G.H. Nieder-Westermann

    2005-01-01

    The outputs from the drift degradation analysis support scientific analyses, models, and design calculations, including the following: (1) Abstraction of Drift Seepage; (2) Seismic Consequence Abstraction; (3) Structural Stability of a Drip Shield Under Quasi-Static Pressure; and (4) Drip Shield Structural Response to Rock Fall. This report has been developed in accordance with ''Technical Work Plan for: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The drift degradation analysis includes the development and validation of rockfall models that approximate phenomenon associated with various components of rock mass behavior anticipated within the repository horizon. Two drift degradation rockfall models have been developed: the rockfall model for nonlithophysal rock and the rockfall model for lithophysal rock. These models reflect the two distinct types of tuffaceous rock at Yucca Mountain. The output of this modeling and analysis activity documents the expected drift deterioration for drifts constructed in accordance with the repository layout configuration (BSC 2004 [DIRS 172801])

  17. Drift in Diffusion Gradients

    Directory of Open Access Journals (Sweden)

    Fabio Marchesoni

    2013-08-01

    Full Text Available The longstanding problem of Brownian transport in a heterogeneous quasi one-dimensional medium with space-dependent self-diffusion coefficient is addressed in the overdamped (zero mass limit. A satisfactory mesoscopic description is obtained in the Langevin equation formalism by introducing an appropriate drift term, which depends on the system macroscopic observables, namely the diffuser concentration and current. The drift term is related to the microscopic properties of the medium. The paradoxical existence of a finite drift at zero current suggests the possibility of designing a Maxwell demon operating between two equilibrium reservoirs at the same temperature.

  18. The Drift Burst Hypothesis

    DEFF Research Database (Denmark)

    Christensen, Kim; Oomen, Roel; Renò, Roberto

    . We then develop a non-parametric test statistic that allows for the identification of drift bursts from noisy high-frequency data. We apply this methodology to a comprehensive set of tick data and show that drift bursts form an integral part of the price dynamics across equities, fixed income......, currencies and commodities. We find that the majority of identified drift bursts are accompanied by strong price reversals and these can therefore be regarded as “flash crashes” that span brief periods of severe market disruption without any material longer term price impacts....

  19. Adaptation to fluctuating temperatures in an RNA virus is driven by the most stringent selective pressure.

    Directory of Open Access Journals (Sweden)

    María Arribas

    Full Text Available The frequency of change in the selective pressures is one of the main factors driving evolution. It is generally accepted that constant environments select specialist organisms whereas changing environments favour generalists. The particular outcome achieved in either case also depends on the relative strength of the selective pressures and on the fitness costs of mutations across environments. RNA viruses are characterized by their high genetic diversity, which provides fast adaptation to environmental changes and helps them evade most antiviral treatments. Therefore, the study of the adaptive possibilities of RNA viruses is highly relevant for both basic and applied research. In this study we have evolved an RNA virus, the bacteriophage Qβ, under three different temperatures that either were kept constant or alternated periodically. The populations obtained were analyzed at the phenotypic and the genotypic level to characterize the evolutionary process followed by the virus in each case and the amount of convergent genetic changes attained. Finally, we also investigated the influence of the pre-existent genetic diversity on adaptation to high temperature. The main conclusions that arise from our results are: i under periodically changing temperature conditions, evolution of bacteriophage Qβ is driven by the most stringent selective pressure, ii there is a high degree of evolutionary convergence between replicated populations and also among populations evolved at different temperatures, iii there are mutations specific of a particular condition, and iv adaptation to high temperatures in populations differing in their pre-existent genetic diversity takes place through the selection of a common set of mutations.

  20. Continental drift before 1900.

    Science.gov (United States)

    Rupke, N A

    1970-07-25

    The idea that Francis Bacon and other seventeenth and eighteenth century thinkers first conceived the notion of continental drift does not stand up to close scrutiny. The few authors who expressed the idea viewed the process as a catastrophic event.

  1. Imprints from genetic drift and mutation imply relative divergence times across marine transition zones in a Pan European small pelagic fish (Sprattus sprattus)

    DEFF Research Database (Denmark)

    Limborg, Morten; Hanel, R.; Debes, P.

    2012-01-01

    Geographic distributions of most temperate marine fishes are affected by postglacial recolonisation events, which have left complex genetic imprints on populations of marine species. This study investigated population structure and demographic history of European sprat (Sprattus sprattus L.) by c...

  2. Drift Scale THM Model

    Energy Technology Data Exchange (ETDEWEB)

    J. Rutqvist

    2004-10-07

    This model report documents the drift scale coupled thermal-hydrological-mechanical (THM) processes model development and presents simulations of the THM behavior in fractured rock close to emplacement drifts. The modeling and analyses are used to evaluate the impact of THM processes on permeability and flow in the near-field of the emplacement drifts. The results from this report are used to assess the importance of THM processes on seepage and support in the model reports ''Seepage Model for PA Including Drift Collapse'' and ''Abstraction of Drift Seepage'', and to support arguments for exclusion of features, events, and processes (FEPs) in the analysis reports ''Features, Events, and Processes in Unsaturated Zone Flow and Transport and Features, Events, and Processes: Disruptive Events''. The total system performance assessment (TSPA) calculations do not use any output from this report. Specifically, the coupled THM process model is applied to simulate the impact of THM processes on hydrologic properties (permeability and capillary strength) and flow in the near-field rock around a heat-releasing emplacement drift. The heat generated by the decay of radioactive waste results in elevated rock temperatures for thousands of years after waste emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, resulting in water redistribution and altered flow paths. These temperatures will also cause thermal expansion of the rock, with the potential of opening or closing fractures and thus changing fracture permeability in the near-field. Understanding the THM coupled processes is important for the performance of the repository because the thermally induced permeability changes potentially effect the magnitude and spatial distribution of percolation flux in the vicinity of the drift, and hence the seepage of water into the drift. This is important because

  3. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    D. Kicker

    2004-01-01

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal stress. (3) The DRKBA

  4. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. Kicker

    2004-09-16

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

  5. The Stringent Response Promotes Antibiotic Resistance Dissemination by Regulating Integron Integrase Expression in Biofilms

    Directory of Open Access Journals (Sweden)

    Emilie Strugeon

    2016-08-01

    Full Text Available Class 1 integrons are genetic systems that enable bacteria to capture and express gene cassettes. These integrons, when isolated in clinical contexts, most often carry antibiotic resistance gene cassettes. They play a major role in the dissemination of antibiotic resistance among Gram-negative bacteria. The key element of integrons is the integrase, which allows gene cassettes to be acquired and shuffled. Planktonic culture experiments have shown that integrase expression is regulated by the bacterial SOS response. In natural settings, however, bacteria generally live in biofilms, which are characterized by strong antibiotic resilience and by increased expression of stress-related genes. Here, we report that under biofilm conditions, the stringent response, which is induced upon starvation, (i increases basal integrase and SOS regulon gene expression via induction of the SOS response and (ii exerts biofilm-specific regulation of the integrase via the Lon protease. This indicates that biofilm environments favor integron-mediated acquisition of antibiotic resistance and other adaptive functions encoded by gene cassettes.

  6. Nonlinear drift tearing mode

    International Nuclear Information System (INIS)

    Zelenyj, L.M.; Kuznetsova, M.M.

    1989-01-01

    Nonlinear study of magnetic perturbation development under single-mode conditions in collision-free plasma in configurations with the magnetic field shear is investigated. Results are obtained with regard of transverse component of electrical field and its effect on ion dynamics within wide range of ion Larmor radius value and values of magnetic field shear. Increments of nonlinear drift tearing mode are obtained and it is shown that excitation drastic conditions of even linearly stable modes are possible. Mechanism of instability nonlinear stabilization is considered and the value of magnetic island at the saturation threshold is estimeted. Energy of nonlinear drift tearing mode is discussed

  7. The episode of genetic drift defining the migration of humans out of Africa is derived from a large east African population size.

    Science.gov (United States)

    Elhassan, Nuha; Gebremeskel, Eyoab Iyasu; Elnour, Mohamed Ali; Isabirye, Dan; Okello, John; Hussien, Ayman; Kwiatksowski, Dominic; Hirbo, Jibril; Tishkoff, Sara; Ibrahim, Muntaser E

    2014-01-01

    Human genetic variation particularly in Africa is still poorly understood. This is despite a consensus on the large African effective population size compared to populations from other continents. Based on sequencing of the mitochondrial Cytochrome C Oxidase subunit II (MT-CO2), and genome wide microsatellite data we observe evidence suggesting the effective size (Ne) of humans to be larger than the current estimates, with a foci of increased genetic diversity in east Africa, and a population size of east Africans being at least 2-6 fold larger than other populations. Both phylogenetic and network analysis indicate that east Africans possess more ancestral lineages in comparison to various continental populations placing them at the root of the human evolutionary tree. Our results also affirm east Africa as the likely spot from which migration towards Asia has taken place. The study reflects the spectacular level of sequence variation within east Africans in comparison to the global sample, and appeals for further studies that may contribute towards filling the existing gaps in the database. The implication of these data to current genomic research, as well as the need to carry out defined studies of human genetic variation that includes more African populations; particularly east Africans is paramount.

  8. The episode of genetic drift defining the migration of humans out of Africa is derived from a large east African population size.

    Directory of Open Access Journals (Sweden)

    Nuha Elhassan

    Full Text Available Human genetic variation particularly in Africa is still poorly understood. This is despite a consensus on the large African effective population size compared to populations from other continents. Based on sequencing of the mitochondrial Cytochrome C Oxidase subunit II (MT-CO2, and genome wide microsatellite data we observe evidence suggesting the effective size (Ne of humans to be larger than the current estimates, with a foci of increased genetic diversity in east Africa, and a population size of east Africans being at least 2-6 fold larger than other populations. Both phylogenetic and network analysis indicate that east Africans possess more ancestral lineages in comparison to various continental populations placing them at the root of the human evolutionary tree. Our results also affirm east Africa as the likely spot from which migration towards Asia has taken place. The study reflects the spectacular level of sequence variation within east Africans in comparison to the global sample, and appeals for further studies that may contribute towards filling the existing gaps in the database. The implication of these data to current genomic research, as well as the need to carry out defined studies of human genetic variation that includes more African populations; particularly east Africans is paramount.

  9. Large planar drift chambers

    CERN Document Server

    Marel, Gérard; Bréhin, S; Devaux, B; Diamant-Berger, Alain M; Leschevin, C; Maillard, J; Malbequi, Y; Martin, H; Patoux, A; Pelle, J; Plancoulaine, J; Tarte, Gérard; Turlay, René

    1977-01-01

    The authors describe 14 m/sup 2/ hexagonal planar drift chambers designed for the neutrino experiment of the CERN-Dortmund-Heidelberg- Saclay Collaboration. Details on mechanical construction, electronic read-out, results on efficiency and accuracy are presented. (6 refs).

  10. IN DRIFT CORROSION PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    D.M. Jolley

    1999-12-02

    As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.

  11. Negative Drift in Populations

    DEFF Research Database (Denmark)

    Lehre, Per Kristian

    2011-01-01

    An important step in gaining a better understanding of the stochastic dynamics of evolving populations, is the development of appropriate analytical tools. We present a new drift theorem for populations that allows properties of their long-term behaviour, e.g. the runtime of evolutionary algorithms...

  12. The KLOE drift chamber

    International Nuclear Information System (INIS)

    Ferrari, A.

    2002-01-01

    The design and construction of the large drift chamber of the KLOE experiment is presented. The track reconstruction is described, together with the calibration method and the monitoring systems. The stability of operation and the performance are studied with samples of e + e - , K S K L and K + K - events

  13. Decreased serologic response in vaccinated military recruits during 2011 correspond to genetic drift in concurrent circulating pandemic A/H1N1 viruses.

    Directory of Open Access Journals (Sweden)

    Dennis J Faix

    Full Text Available Population-based febrile respiratory illness surveillance conducted by the Department of Defense contributes to an estimate of vaccine effectiveness. Between January and March 2011, 64 cases of 2009 A/H1N1 (pH1N1, including one fatality, were confirmed in immunized recruits at Fort Jackson, South Carolina, suggesting insufficient efficacy for the pH1N1 component of the live attenuated influenza vaccine (LAIV.To test serologic protection, serum samples were collected at least 30 days post-vaccination from recruits at Fort Jackson (LAIV, Parris Island (LAIV and trivalent inactivated vaccine [TIV] at Cape May, New Jersey (TIV and responses measured against pre-vaccination sera. A subset of 78 LAIV and 64 TIV sera pairs from recruits who reported neither influenza vaccination in the prior year nor fever during training were tested by microneutralization (MN and hemagglutination inhibition (HI assays. MN results demonstrated that seroconversion in paired sera was greater in those who received TIV versus LAIV (74% and 37%. Additionally, the fold change associated with TIV vaccination was significantly different between circulating (2011 versus the vaccine strain (2009 of pH1N1 viruses (ANOVA p value = 0.0006. HI analyses revealed similar trends. Surface plasmon resonance (SPR analysis revealed that the quantity, IgG/IgM ratios, and affinity of anti-HA antibodies were significantly greater in TIV vaccinees. Finally, sequence analysis of the HA1 gene in concurrent circulating 2011 pH1N1 isolates from Fort Jackson exhibited modest amino acid divergence from the vaccine strain.Among military recruits in 2011, serum antibody response differed by vaccine type (LAIV vs. TIV and pH1N1 virus year (2009 vs. 2011. We hypothesize that antigen drift in circulating pH1N1 viruses contributed to reduce vaccine effectiveness at Fort Jackson. Our findings have wider implications regarding vaccine protection from circulating pH1N1 viruses in 2011-2012.

  14. Dike Propagation Near Drifts

    Energy Technology Data Exchange (ETDEWEB)

    NA

    2002-03-04

    The purpose of this Analysis and Model Report (AMR) supporting the Site Recommendation/License Application (SR/LA) for the Yucca Mountain Project is the development of elementary analyses of the interactions of a hypothetical dike with a repository drift (i.e., tunnel) and with the drift contents at the potential Yucca Mountain repository. This effort is intended to support the analysis of disruptive events for Total System Performance Assessment (TSPA). This AMR supports the Process Model Report (PMR) on disruptive events (CRWMS M&O 2000a). This purpose is documented in the development plan (DP) ''Coordinate Modeling of Dike Propagation Near Drifts Consequences for TSPA-SR/LA'' (CRWMS M&O 2000b). Evaluation of that Development Plan and the work to be conducted to prepare Interim Change Notice (ICN) 1 of this report, which now includes the design option of ''Open'' drifts, indicated that no revision to that DP was needed. These analyses are intended to provide reasonable bounds for a number of expected effects: (1) Temperature changes to the waste package from exposure to magma; (2) The gas flow available to degrade waste containers during the intrusion; (3) Movement of the waste package as it is displaced by the gas, pyroclasts and magma from the intruding dike (the number of packages damaged); (4) Movement of the backfill (Backfill is treated here as a design option); (5) The nature of the mechanics of the dike/drift interaction. These analyses serve two objectives: to provide preliminary analyses needed to support evaluation of the consequences of an intrusive event and to provide a basis for addressing some of the concerns of the Nuclear Regulatory Commission (NRC) expressed in the Igneous Activity Issue Resolution Status Report.

  15. Dike Propagation Near Drifts

    International Nuclear Information System (INIS)

    2002-01-01

    The purpose of this Analysis and Model Report (AMR) supporting the Site Recommendation/License Application (SR/LA) for the Yucca Mountain Project is the development of elementary analyses of the interactions of a hypothetical dike with a repository drift (i.e., tunnel) and with the drift contents at the potential Yucca Mountain repository. This effort is intended to support the analysis of disruptive events for Total System Performance Assessment (TSPA). This AMR supports the Process Model Report (PMR) on disruptive events (CRWMS M and O 2000a). This purpose is documented in the development plan (DP) ''Coordinate Modeling of Dike Propagation Near Drifts Consequences for TSPA-SR/LA'' (CRWMS M and O 2000b). Evaluation of that Development Plan and the work to be conducted to prepare Interim Change Notice (ICN) 1 of this report, which now includes the design option of ''Open'' drifts, indicated that no revision to that DP was needed. These analyses are intended to provide reasonable bounds for a number of expected effects: (1) Temperature changes to the waste package from exposure to magma; (2) The gas flow available to degrade waste containers during the intrusion; (3) Movement of the waste package as it is displaced by the gas, pyroclasts and magma from the intruding dike (the number of packages damaged); (4) Movement of the backfill (Backfill is treated here as a design option); (5) The nature of the mechanics of the dike/drift interaction. These analyses serve two objectives: to provide preliminary analyses needed to support evaluation of the consequences of an intrusive event and to provide a basis for addressing some of the concerns of the Nuclear Regulatory Commission (NRC) expressed in the Igneous Activity Issue Resolution Status Report

  16. Style drift in private equity

    NARCIS (Netherlands)

    Cumming, D.; Fleming, G.; Schwienbacher, A.

    2009-01-01

    We introduce the concept of style drift to private equity investment. We present theory and evidence pertaining to style drifts in terms of a fund manager's stated focus on particular stages of entrepreneurial development. We develop a model that derives conditions under which style drifts are less

  17. Diogene pictorial drift chamber

    International Nuclear Information System (INIS)

    Gosset, J.

    1984-01-01

    A pictorial drift chamber, called DIOGENE, has been installed at Saturne in order to study central collisions of high energy heavy ions. It has been adapted from the JADE internal detector, with two major differences to be taken into account. First, the center-of-mass of these collisions is not identical to the laboratory reference frame. Second, the energy loss and the momentum ranges of the particles to be detected are different from the ones in JADE. It was also tried to keep the cost as small as possible, hence the choice of minimum size and minimum number of sensitive wires. Moreover the wire planes are shifted from the beam axis: this trick helps very much to quickly reject the bad tracks caused by the ambiguity of measuring drift distances (positive or negative) through times (always positive)

  18. Laboratory Course on Drift Chambers

    International Nuclear Information System (INIS)

    Garcia-Ferreira, Ix-B.; Garcia-Herrera, J.; Villasenor, L.

    2006-01-01

    Drift chambers play an important role in particle physics experiments as tracking detectors. We started this laboratory course with a brief review of the theoretical background and then moved on to the the experimental setup which consisted of a single-sided, single-cell drift chamber. We also used a plastic scintillator paddle, standard P-10 gas mixture (90% Ar, 10% CH4) and a collimated 90Sr source. During the laboratory session the students performend measurements of the following quantities: a) drift velocities and their variations as function of the drift field; b) gas gains and c) diffusion of electrons as they drifted in the gas

  19. The mechanism of heterogeneous beta-lactam resistance in MRSA: key role of the stringent stress response.

    Directory of Open Access Journals (Sweden)

    Choonkeun Kim

    Full Text Available All methicillin resistant S. aureus (MRSA strains carry an acquired genetic determinant--mecA or mecC--which encode for a low affinity penicillin binding protein -PBP2A or PBP2A'--that can continue the catalysis of peptidoglycan transpeptidation in the presence of high concentrations of beta-lactam antibiotics which would inhibit the native PBPs normally involved with the synthesis of staphylococcal cell wall peptidoglycan. In contrast to this common genetic and biochemical mechanism carried by all MRSA strains, the level of beta-lactam antibiotic resistance shows a very wide strain to strain variation, the mechanism of which has remained poorly understood. The overwhelming majority of MRSA strains produce a unique--heterogeneous--phenotype in which the great majority of the bacteria exhibit very poor resistance often close to the MIC value of susceptible S. aureus strains. However, cultures of such heterogeneously resistant MRSA strains also contain subpopulations of bacteria with extremely high beta-lactam MIC values and the resistance level and frequency of the highly resistant cells in such strain is a characteristic of the particular MRSA clone. In the study described in this communication, we used a variety of experimental models to understand the mechanism of heterogeneous beta-lactam resistance. Methicillin-susceptible S. aureus (MSSA that received the mecA determinant in the laboratory either on a plasmid or in the form of a chromosomal SCCmec cassette, generated heterogeneously resistant cultures and the highly resistant subpopulations that emerged in these models had increased levels of PBP2A and were composed of bacteria in which the stringent stress response was induced. Each of the major heterogeneously resistant clones of MRSA clinical isolates could be converted to express high level and homogeneous resistance if the growth medium contained an inducer of the stringent stress response.

  20. Rapid Curtailing of the Stringent Response by Toxin-Antitoxin Encoded mRNases

    DEFF Research Database (Denmark)

    Tian, Chengzhe; Roghanian, Mohammad; Jørgensen, Mikkel Girke

    2016-01-01

    Escherichia coli regulates its metabolism to adapt to changes in the environment, in particular to stressful downshifts in nutrient quality. Such shifts elicit the so-called stringent response coordinated by the alarmone guanosine tetra- and pentaphosphate [(p)ppGpp]. At sudden amino-acid (aa......RNase-encoding TA modules present in the wt strain. This observation suggested that toxins are part of the negative feedback to control the (p)ppGpp level during early stringent response. We built a ribosome trafficking model to evaluate the fold of increase in the RelA activity just after the onset of aa...... %. IMPORTANCE: The early stringent response elicited by amino-acid starvation is controlled by a sharp increase of the cellular (p)ppGpp level. Toxin-antitoxin encoded mRNases are activated by (p)ppGpp through enhanced degradation of antitoxins. The present work shows that this activation happens at a very...

  1. Drifting black aurorae?

    International Nuclear Information System (INIS)

    Schoute-Vanneck, H.; Scourfield, M.W.J.; Nielsen, E.

    1990-01-01

    Characteristics of eastward drifting forms, previously described in the literature as black aurorae, have been identified in low-light level TV camera data. The TV field of view was within the field of view of STARE and that of an all-sky camera. On the basis of these observations the authors propose that these auroral forms are a manifestation of folds or waves on the borders of auroral bands propagating along the dark regions between neighboring auroral bands. Conditions under which the folds or waves occur are compatible with their formation by the Kelvin-Helmholtz electrostatic instability

  2. ABSTRACTION OF DRIFT SEEPAGE

    International Nuclear Information System (INIS)

    Wilson, Michael L.

    2001-01-01

    Drift seepage refers to flow of liquid water into repository emplacement drifts, where it can potentially contribute to degradation of the engineered systems and release and transport of radionuclides within the drifts. Because of these important effects, seepage into emplacement drifts is listed as a ''principal factor for the postclosure safety case'' in the screening criteria for grading of data in Attachment 1 of AP-3.15Q, Rev. 2, ''Managing Technical Product Inputs''. Abstraction refers to distillation of the essential components of a process model into a form suitable for use in total-system performance assessment (TSPA). Thus, the purpose of this analysis/model is to put the information generated by the seepage process modeling in a form appropriate for use in the TSPA for the Site Recommendation. This report also supports the Unsaturated-Zone Flow and Transport Process Model Report. The scope of the work is discussed below. This analysis/model is governed by the ''Technical Work Plan for Unsaturated Zone Flow and Transport Process Model Report'' (CRWMS MandO 2000a). Details of this activity are in Addendum A of the technical work plan. The original Work Direction and Planning Document is included as Attachment 7 of Addendum A. Note that the Work Direction and Planning Document contains tasks identified for both Performance Assessment Operations (PAO) and Natural Environment Program Operations (NEPO). Only the PAO tasks are documented here. The planning for the NEPO activities is now in Addendum D of the same technical work plan and the work is documented in a separate report (CRWMS MandO 2000b). The Project has been reorganized since the document was written. The responsible organizations in the new structure are the Performance Assessment Department and the Unsaturated Zone Department, respectively. The work plan for the seepage abstraction calls for determining an appropriate abstraction methodology, determining uncertainties in seepage, and providing

  3. Phylogenetic analysis of proteins involved in the stringent response in plant cells.

    Science.gov (United States)

    Ito, Doshun; Ihara, Yuta; Nishihara, Hidenori; Masuda, Shinji

    2017-07-01

    The nucleotide (p)ppGpp is a second messenger that controls the stringent response in bacteria. The stringent response modifies expression of a large number of genes and metabolic processes and allows bacteria to survive under fluctuating environmental conditions. Recent genome sequencing analyses have revealed that genes responsible for the stringent response are also found in plants. These include (p)ppGpp synthases and hydrolases, RelA/SpoT homologs (RSHs), and the pppGpp-specific phosphatase GppA/Ppx. However, phylogenetic relationship between enzymes involved in bacterial and plant stringent responses is as yet generally unclear. Here, we investigated the origin and evolution of genes involved in the stringent response in plants. Phylogenetic analysis and primary structures of RSH homologs from different plant phyla (including Embryophyta, Charophyta, Chlorophyta, Rhodophyta and Glaucophyta) indicate that RSH gene families were introduced into plant cells by at least two independent lateral gene transfers from the bacterial Deinococcus-Thermus phylum and an unidentified bacterial phylum; alternatively, they were introduced into a proto-plant cell by a lateral gene transfer from the endosymbiotic cyanobacterium followed by gene loss of an ancestral RSH gene in the cyanobacterial linage. Phylogenetic analysis of gppA/ppx families indicated that plant gppA/ppx homologs form an individual cluster in the phylogenetic tree, and show a sister relationship with some bacterial gppA/ppx homologs. Although RSHs contain a plastidial transit peptide at the N terminus, GppA/Ppx homologs do not, suggesting that plant GppA/Ppx homologs function in the cytosol. These results reveal that a proto-plant cell obtained genes for the stringent response by lateral gene transfer events from different bacterial phyla and have utilized them to control metabolism in plastids and the cytosol.

  4. The CLEO III drift chamber

    CERN Document Server

    Peterson, D; Briere, R A; Chen, G; Cronin-Hennessy, D; Csorna, S; Dickson, M; Dombrowski, S V; Ecklund, K M; Lyon, A; Marka, S; Meyer, T O; Patterson, J R; Sadoff, A; Thies, P; Thorndike, E H; Urner, D

    2002-01-01

    The CLEO group at the Cornell Electron Storage Ring has constructed and commissioned a new central drift chamber. With 9796 cells arranged in 47 layers ranging in radius from 13.2 to 79 cm, the new drift chamber has a smaller outer radius and fewer wires than the drift chamber it replaces, but allows the CLEO tracking system to have improved momentum resolution. Reduced scattering material in the chamber gas and in the inner skin separating the drift chamber from the silicon vertex detector provides a reduction of the multiple scattering component of the momentum resolution and an extension of the usable measurement length into the silicon. Momentum resolution is further improved through quality control in wire positioning and symmetry of the electric fields in the drift cells which have provided a reduction in the spatial resolution to 88 mu m (averaged over the full drift range).

  5. Electronics for proportional drift tubes

    International Nuclear Information System (INIS)

    Fremont, G.; Friend, B.; Mess, K.H.; Schmidt-Parzefall, W.; Tarle, J.C.; Verweij, H.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration); Geske, K.; Riege, H.; Schuett, J.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration); Semenov, Y.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration)

    1980-01-01

    An electronic system for the read-out of a large number of proportional drift tubes (16,000) has been designed. This system measures deposited charge and drift-time of the charge of a particle traversing a proportional drift tube. A second event can be accepted during the read-out of the system. Up to 40 typical events can be collected and buffered before a data transfer to a computer is necessary. (orig.)

  6. The stringent response regulates adaptation to darkness in the cyanobacterium Synechococcus elongatus.

    Science.gov (United States)

    Hood, Rachel D; Higgins, Sean A; Flamholz, Avi; Nichols, Robert J; Savage, David F

    2016-08-16

    The cyanobacterium Synechococcus elongatus relies upon photosynthesis to drive metabolism and growth. During darkness, Synechococcus stops growing, derives energy from its glycogen stores, and greatly decreases rates of macromolecular synthesis via unknown mechanisms. Here, we show that the stringent response, a stress response pathway whose genes are conserved across bacteria and plant plastids, contributes to this dark adaptation. Levels of the stringent response alarmone guanosine 3'-diphosphate 5'-diphosphate (ppGpp) rise after a shift from light to dark, indicating that darkness triggers the same response in cyanobacteria as starvation in heterotrophic bacteria. High levels of ppGpp are sufficient to stop growth and dramatically alter many aspects of cellular physiology, including levels of photosynthetic pigments and polyphosphate, DNA content, and the rate of translation. Cells unable to synthesize ppGpp display pronounced growth defects after exposure to darkness. The stringent response regulates expression of a number of genes in Synechococcus, including ribosomal hibernation promoting factor (hpf), which causes ribosomes to dimerize in the dark and may contribute to decreased translation. Although the metabolism of Synechococcus differentiates it from other model bacterial systems, the logic of the stringent response remains remarkably conserved, while at the same time having adapted to the unique stresses of the photosynthetic lifestyle.

  7. Structural characterization of the stringent response related exopolyphosphatase/guanosine pentaphosphate phosphohydrolase protein family

    DEFF Research Database (Denmark)

    Kristensen, Ole; Laurberg, Martin; Liljas, Anders

    2004-01-01

    Exopolyphosphatase/guanosine pentaphosphate phosphohydrolase (PPX/GPPA) enzymes play central roles in the bacterial stringent response induced by starvation. The high-resolution crystal structure of the putative Aquifex aeolicus PPX/GPPA phosphatase from the actin-like ATPase domain superfamily h...

  8. The KLOE drift chamber

    CERN Document Server

    Adinolfi, M; Ambrosino, F; Andryakov, A; Antonelli, A; Antonelli, M; Anulli, F; Bacci, C; Bankamp, A; Barbiellini, G; Bellini, F; Bencivenni, G; Bertolucci, Sergio; Bini, C; Bloise, C; Bocci, V; Bossi, F; Branchini, P; Bulychjov, S A; Cabibbo, G; Calcaterra, A; Caloi, R; Campana, P; Capon, G; Carboni, G; Cardini, A; Casarsa, M; Cataldi, G; Ceradini, F; Cervelli, F; Cevenini, F; Chiefari, G; Ciambrone, P; Conetti, S; Conticelli, S; Lucia, E D; Robertis, G D; Sangro, R D; Simone, P D; Zorzi, G D; Dell'Agnello, S; Denig, A; Domenico, A D; Donato, C D; Falco, S D; Doria, A; Drago, E; Elia, V; Erriquez, O; Farilla, A; Felici, G; Ferrari, A; Ferrer, M L; Finocchiaro, G; Forti, C; Franceschi, A; Franzini, P; Gao, M L; Gatti, C; Gauzzi, P; Giovannella, S; Golovatyuk, V; Gorini, E; Grancagnolo, F; Grandegger, W; Graziani, E; Guarnaccia, P; Von Hagel, U; Han, H G; Han, S W; Huang, X; Incagli, M; Ingrosso, L; Jang, Y Y; Kim, W; Kluge, W; Kulikov, V; Lacava, F; Lanfranchi, G; Lee-Franzini, J; Lomtadze, F; Luisi, C; Mao Chen Sheng; Martemyanov, M; Matsyuk, M; Mei, W; Merola, L; Messi, R; Miscetti, S; Moalem, A; Moccia, S; Moulson, M; Müller, S; Murtas, F; Napolitano, M; Nedosekin, A; Panareo, M; Pacciani, L; Pagès, P; Palutan, M; Paoluzi, L; Pasqualucci, E; Passalacqua, L; Passaseo, M; Passeri, A; Patera, V; Petrolo, E; Petrucci, Guido; Picca, D; Pirozzi, G; Pistillo, C; Pollack, M; Pontecorvo, L; Primavera, M; Ruggieri, F; Santangelo, P; Santovetti, E; Saracino, G; Schamberger, R D; Schwick, C; Sciascia, B; Sciubba, A; Scuri, F; Sfiligoi, I; Shan, J; Silano, P; Spadaro, T; Spagnolo, S; Spiriti, E; Stanescu, C; Tong, G L; Tortora, L; Valente, E; Valente, P; Valeriani, B; Venanzoni, G; Veneziano, Stefano; Wu, Y; Xie, Y G; Zhao, P P; Zhou, Y

    2001-01-01

    The tracking detector of the KLOE experiment is 4 m diameter, 3.3 m length drift chamber, designed to contain a large fraction of the decays of low-energy K sub L produced at the Frascati DAPHINE phi-factory. The chamber is made by a thin carbon fiber structure and operated with a helium-based gas mixture in order to minimise conversion of low-energy photons and multiple scattering inside the sensitive volume. The tracking information is provided by 58 layers of stereo wires defing 12,582 cells, 2x2 cm sup 2 in size in the 12 innermost layers and 3x3 cm sup 2 in the outer ones. Details of the chamber design, calibration procedure and tracking performances are presented.

  9. The KLOE drift chamber

    International Nuclear Information System (INIS)

    Adinolfi, M.; Aloisio, A.; Ambrosino, F.; Andryakov, A.; Antonelli, A.; Antonelli, M.; Anulli, F.; Bacci, C.; Bankamp, A.; Barbiellini, G.; Bellini, F.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S.A.; Cabibbo, G.; Calcaterra, A.; Caloi, R.; Campana, P.; Capon, G.; Carboni, G.; Cardini, A.; Casarsa, M.; Cataldi, G.; Ceradini, F.; Cervelli, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; Conticelli, S.; Lucia, E. De; Robertis, G. De; Sangro, R. De; Simone, P. De; Zorzi, G. De; Dell'Agnello, S.; Denig, A.; Domenico, A. Di; Donato, C. Di; Falco, S. Di; Doria, A.; Drago, E.; Elia, V.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M.L.; Finocchiaro, G.; Forti, C.; Franceschi, A.; Franzini, P.; Gao, M.L.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Golovatyuk, V.; Gorini, E.; Grancagnolo, F.; Grandegger, W.; Graziani, E.; Guarnaccia, P.; Hagel, U.V.; Han, H.G.; Han, S.W.; Huang, X.; Incagli, M.; Ingrosso, L.; Jang, Y.Y.; Kim, W.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Lomtadze, F.; Luisi, C.; Mao, C.S.; Martemianov, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moalem, A.; Moccia, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nedosekin, A.; Panareo, M.; Pacciani, L.; Pages, P.; Palutan, M.; Paoluzi, L.; Pasqualucci, E.; Passalacqua, L.; Passaseo, M.; Passeri, A.; Patera, V.; Petrolo, E.; Petrucci, G.; Picca, D.; Pirozzi, G.; Pistillo, C.; Pollack, M.; Pontecorvo, L.; Primavera, M.; Ruggieri, F.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R.D.; Schwick, C.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Shan, J.; Silano, P.; Spadaro, T.; Spagnolo, S.; Spiriti, E.; Stanescu, C.; Tong, G.L.; Tortora, L.; Valente, E.; Valente, P.; Valeriani, B.; Venanzoni, G.; Veneziano, S.; Wu, Y.; Xie, Y.G.; Zhao, P.P.; Zhou, Y.

    2001-01-01

    The tracking detector of the KLOE experiment is 4 m diameter, 3.3 m length drift chamber, designed to contain a large fraction of the decays of low-energy K L produced at the Frascati DAPHINE phi-factory. The chamber is made by a thin carbon fiber structure and operated with a helium-based gas mixture in order to minimise conversion of low-energy photons and multiple scattering inside the sensitive volume. The tracking information is provided by 58 layers of stereo wires defing 12,582 cells, 2x2 cm 2 in size in the 12 innermost layers and 3x3 cm 2 in the outer ones. Details of the chamber design, calibration procedure and tracking performances are presented

  10. Progress in semiconductor drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Walton, J.; Gatti, E.

    1985-01-01

    Progress in testing semiconductor drift detectors is reported. Generally better position and energy resolutions were obtained than resolutions published previously. The improvement is mostly due to new electronics better matched to different detectors. It is shown that semiconductor drift detectors are becoming versatile and reliable detectors for position and energy measurements

  11. Nonlinear theory of drift instability

    International Nuclear Information System (INIS)

    Hatori, T.

    1981-01-01

    In this chapter, we review recent works on the analytical and numerical analysis for the nonlinear evolution of drift instabilities. Only the case of a coherent wave is considered. Contributions to the turbulence theory for drift instabilities are already presented in Chapter 4. (author)

  12. CTF Void Drift Validation Study

    Energy Technology Data Exchange (ETDEWEB)

    Salko, Robert K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gosdin, Chris [Pennsylvania State Univ., University Park, PA (United States); Avramova, Maria N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gergar, Marcus [Pennsylvania State Univ., University Park, PA (United States)

    2015-10-26

    This milestone report is a summary of work performed in support of expansion of the validation and verification (V&V) matrix for the thermal-hydraulic subchannel code, CTF. The focus of this study is on validating the void drift modeling capabilities of CTF and verifying the supporting models that impact the void drift phenomenon. CTF uses a simple turbulent-diffusion approximation to model lateral cross-flow due to turbulent mixing and void drift. The void drift component of the model is based on the Lahey and Moody model. The models are a function of two-phase mass, momentum, and energy distribution in the system; therefore, it is necessary to correctly model the ow distribution in rod bundle geometry as a first step to correctly calculating the void distribution due to void drift.

  13. Global gene expression during stringent response in Corynebacterium glutamicum in presence and absence of the rel gene encoding (pppGpp synthase

    Directory of Open Access Journals (Sweden)

    Kalinowski Jörn

    2006-09-01

    Full Text Available Background The stringent response is the initial reaction of microorganisms to nutritional stress. During stringent response the small nucleotides (pppGpp act as global regulators and reprogram bacterial transcription. In this work, the genetic network controlled by the stringent response was characterized in the amino acid-producing Corynebacterium glutamicum. Results The transcriptome of a C. glutamicum rel gene deletion mutant, unable to synthesize (pppGpp and to induce the stringent response, was compared with that of its rel-proficient parent strain by microarray analysis. A total of 357 genes were found to be transcribed differentially in the rel-deficient mutant strain. In a second experiment, the stringent response was induced by addition of DL-serine hydroxamate (SHX in early exponential growth phase. The time point of the maximal effect on transcription was determined by real-time RT-PCR using the histidine and serine biosynthetic genes. Transcription of all of these genes reached a maximum at 10 minutes after SHX addition. Microarray experiments were performed comparing the transcriptomes of SHX-induced cultures of the rel-proficient strain and the rel mutant. The differentially expressed genes were grouped into three classes. Class A comprises genes which are differentially regulated only in the presence of an intact rel gene. This class includes the non-essential sigma factor gene sigB which was upregulated and a large number of genes involved in nitrogen metabolism which were downregulated. Class B comprises genes which were differentially regulated in response to SHX in both strains, independent of the rel gene. A large number of genes encoding ribosomal proteins fall into this class, all being downregulated. Class C comprises genes which were differentially regulated in response to SHX only in the rel mutant. This class includes genes encoding putative stress proteins and global transcriptional regulators that might be

  14. Pulsed Drift Tube Accelerator

    International Nuclear Information System (INIS)

    Faltens, A.

    2004-01-01

    The pulsed drift-tube accelerator (DTA) concept was revived by Joe Kwan and John Staples and is being considered for the HEDP/WDM application. It could be used to reach the full energy or as an intermediate accelerator between the diode and a high gradient accelerator such as multi-beam r.f. In the earliest LBNL HIF proposals and conceptual drivers it was used as an extended injector to reach energies where an induction linac with magnetic quadrupoles is the best choice. For HEDP, because of the very short pulse duration, the DTA could provide an acceleration rate of about 1MV/m. This note is divided into two parts: the first, a design based on existing experience; the second, an optimistic extrapolation. The first accelerates 16 parallel K + beams at a constant line charge density of 0.25(micro) C/m per beam to 10 MeV; the second uses a stripper and charge selector at around 4MeV followed by further acceleration to reach 40 MeV. Both benefit from more compact sources than the present 2MV injector source, although that beam is the basis of the first design and is a viable option. A pulsed drift-tube accelerator was the first major HIF experiment at LBNL. It was designed to produce a 2(micro)s rectangular 1 Ampere C s + beam at 2MeV. It ran comfortably at 1.6MeV for several years, then at lower voltages and currents for other experiments, and remnants of that experiment are in use in present experiments, still running 25 years later. The 1A current, completely equivalent to 1.8A K + , was chosen to be intermediate between the beamlets appropriate for a multi-beam accelerator, and a single beam of, say, 10A, at injection energies. The original driver scenarios using one large beam on each side of the reactor rapidly fell out of favor because of the very high transverse and longitudinal fields from the beam space charge, circa 1MV/cm and 250 kV/cm respectively, near the chamber and because of aberrations in focusing a large diameter beam down to a 1mm radius spot at a

  15. Drifting oscillations in axion monodromy

    International Nuclear Information System (INIS)

    Flauger, Raphael; Westphal, Alexander

    2014-12-01

    We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.

  16. Drifting oscillations in axion monodromy

    Energy Technology Data Exchange (ETDEWEB)

    Flauger, Raphael [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); McAllister, Liam [Department of Physics, Cornell University, Ithaca, NY 14853 (United States); Silverstein, Eva [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305 (United States); Westphal, Alexander, E-mail: flauger@physics.ucsd.edu, E-mail: mcallister@cornell.edu, E-mail: evas@stanford.edu, E-mail: alexander.westphal@desy.de [Theory Group, Deutsches Elektronen-Synchrotron DESY, D-22603 Hamburg (Germany)

    2017-10-01

    We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.

  17. The controlled-drift detector

    CERN Document Server

    Castoldi, A; Guazzoni, C; Longoni, A; Rehak, P; Strüder, L

    2000-01-01

    A new position-sensing X-ray detector is presented. The novel device is called Controlled-Drift Detector (CDD). The detector is fully depleted and is operated by switching between integration and drift modes. The relevant details of the detector design are discussed. A complete experimental characterization of the fast readout of the integrated signal charges achievable with static drift fields in the range 100-400 V/cm has been carried out. Preliminary measurements to evaluate the charge-handling capacity are also shown. The CDD can provide unambiguous two-dimensional position measurement, high-resolution X-ray spectroscopy and time resolution below 1 ms.

  18. The controlled-drift detector

    Energy Technology Data Exchange (ETDEWEB)

    Castoldi, A. E-mail: andrea.castoldi@polimi.it; Gatti, E.; Guazzoni, C.; Longoni, A.; Rehak, P.; Strueder, L

    2000-01-11

    A new position-sensing X-ray detector is presented. The novel device is called Controlled-Drift Detector (CDD). The detector is fully depleted and is operated by switching between integration and drift modes. The relevant details of the detector design are discussed. A complete experimental characterization of the fast readout of the integrated signal charges achievable with static drift fields in the range 100-400 V/cm has been carried out. Preliminary measurements to evaluate the charge-handling capacity are also shown. The CDD can provide unambiguous two-dimensional position measurement, high-resolution X-ray spectroscopy and time resolution below 1 ms.

  19. Drift tubes of Linac 2

    CERN Multimedia

    Photographic Service

    1977-01-01

    Being redied for installation, those at the right are for tank 1, those on the left for tank 2. Contrary to Linac 1, which had drift-tubes supported on stems, here the tubes are suspended, for better mechanical stability.

  20. The Stringent Response Induced by Phosphate Limitation Promotes Purine Salvage in Agrobacterium fabrum.

    Science.gov (United States)

    Sivapragasam, Smitha; Deochand, Dinesh K; Meariman, Jacob K; Grove, Anne

    2017-10-31

    Agrobacterium fabrum induces tumor growth in susceptible plant species. The upregulation of virulence genes that occurs when the bacterium senses plant-derived compounds is enhanced by acidic pH and limiting inorganic phosphate. Nutrient starvation may also trigger the stringent response, and purine salvage is among the pathways expected to be favored under such conditions. We show here that phosphate limitation induces the stringent response, as evidenced by production of (p)ppGpp, and that the xdhCSML operon encoding the purine salvage enzyme xanthine dehydrogenase is upregulated ∼15-fold. The xdhCSML operon is under control of the TetR family transcription factor XdhR; direct binding of ppGpp to XdhR attenuates DNA binding, and the enhanced xdhCSML expression correlates with increased cellular levels of (p)ppGpp. Xanthine dehydrogenase may also divert purines away from salvage pathways to form urate, the ligand for the transcription factor PecS, which in the plant pathogen Dickeya dadantii is a key regulator of virulence gene expression. However, urate levels remain low under conditions that produce increased levels of xdhCSML expression, and neither acidic pH nor limiting phosphate results in induction of genes under control of PecS. Instead, expression of such genes is induced only by externally supplemented urate. Taken together, our data indicate that purine salvage is favored during the stringent response induced by phosphate starvation, suggesting that control of this pathway may constitute a novel approach to modulating virulence. Because bacterial purine catabolism appears to be unaffected, as evidenced by the absence of urate accumulation, we further propose that the PecS regulon is induced by only host-derived urate.

  1. The Drifting Star

    Science.gov (United States)

    2008-04-01

    By studying in great detail the 'ringing' of a planet-harbouring star, a team of astronomers using ESO's 3.6-m telescope have shown that it must have drifted away from the metal-rich Hyades cluster. This discovery has implications for theories of star and planet formation, and for the dynamics of our Milky Way. ESO PR Photo 09a/08 ESO PR Photo 09a/08 Iota Horologii The yellow-orange star Iota Horologii, located 56 light-years away towards the southern Horologium ("The Clock") constellation, belongs to the so-called "Hyades stream", a large number of stars that move in the same direction. Previously, astronomers using an ESO telescope had shown that the star harbours a planet, more than 2 times as large as Jupiter and orbiting in 320 days (ESO 12/99). But until now, all studies were unable to pinpoint the exact characteristics of the star, and hence to understand its origin. A team of astronomers, led by Sylvie Vauclair from the University of Toulouse, France, therefore decided to use the technique of 'asteroseismology' to unlock the star's secrets. "In the same way as geologists monitor how seismic waves generated by earthquakes propagate through the Earth and learn about the inner structure of our planet, it is possible to study sound waves running through a star, which forms a sort of large, spherical bell," says Vauclair. The 'ringing' from this giant musical instrument provides astronomers with plenty of information about the physical conditions in the star's interior. And to 'listen to the music', the astronomers used one of the best instruments available. The observations were conducted in November 2006 during 8 consecutive nights with the state-of-the-art HARPS spectrograph mounted on the ESO 3.6-m telescope at La Silla. Up to 25 'notes' could be identified in the unique dataset, most of them corresponding to waves having a period of about 6.5 minutes. These observations allowed the astronomers to obtain a very precise portrait of Iota Horologii: its

  2. An exponential integrator for the drift-kinetic model

    Science.gov (United States)

    Crouseilles, Nicolas; Einkemmer, Lukas; Prugger, Martina

    2018-03-01

    We propose an exponential integrator for the drift-kinetic equation in cylindrical geometry. This approach removes the CFL condition from the linear part of the system (which is often the most stringent requirement in practice) and treats the remainder explicitly using Arakawa's finite difference scheme. The present approach is mass conservative, up to machine precision, and significantly reduces the computational effort per time step. In addition, we demonstrate the efficiency of our method by performing numerical simulations in the context of the ion temperature gradient instability. In particular, we find that our numerical method can take time steps comparable to what has been reported in the literature for the (predominantly used) splitting approach. In addition, the proposed numerical method has significant advantages with respect to conservation of energy and efficient higher order methods can be obtained easily. We demonstrate this by investigating the performance of a fourth order implementation.

  3. Characteristic parameters of drift chambers calculation

    International Nuclear Information System (INIS)

    Duran, I.; Martinez-Laso, L.

    1989-01-01

    We present here the methods we used to analyse the characteristic parameters of drift chambers. The algorithms to calculate the electric potential in any point for any drift chamber geometry are presented. We include the description of the programs used to calculate the electric field, the drift paths, the drift velocity and the drift time. The results and the errors are discussed. (Author) 7 refs

  4. In-Drift Microbial Communities

    International Nuclear Information System (INIS)

    Jolley, D.

    2000-01-01

    As directed by written work direction (CRWMS M and O 1999f), Performance Assessment (PA) developed a model for microbial communities in the engineered barrier system (EBS) as documented here. The purpose of this model is to assist Performance Assessment and its Engineered Barrier Performance Section in modeling the geochemical environment within a potential repository drift for TSPA-SR/LA, thus allowing PA to provide a more detailed and complete near-field geochemical model and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). This model and its predecessor (the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document, CRWMS M and O 1998a) was developed to respond to the applicable KTIs. Additionally, because of the previous development of the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a), the M and O was effectively able to resolve a previous KTI concern regarding the effects of microbial processes on seepage and flow (NRC 1998). This document supercedes the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a). This document provides the conceptual framework of the revised in-drift microbial communities model to be used in subsequent performance assessment (PA) analyses

  5. In-Drift Microbial Communities

    Energy Technology Data Exchange (ETDEWEB)

    D. Jolley

    2000-11-09

    As directed by written work direction (CRWMS M and O 1999f), Performance Assessment (PA) developed a model for microbial communities in the engineered barrier system (EBS) as documented here. The purpose of this model is to assist Performance Assessment and its Engineered Barrier Performance Section in modeling the geochemical environment within a potential repository drift for TSPA-SR/LA, thus allowing PA to provide a more detailed and complete near-field geochemical model and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). This model and its predecessor (the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document, CRWMS M and O 1998a) was developed to respond to the applicable KTIs. Additionally, because of the previous development of the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a), the M and O was effectively able to resolve a previous KTI concern regarding the effects of microbial processes on seepage and flow (NRC 1998). This document supercedes the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a). This document provides the conceptual framework of the revised in-drift microbial communities model to be used in subsequent performance assessment (PA) analyses.

  6. The CLAS drift chamber system

    CERN Document Server

    Mestayer, M D; Asavapibhop, B; Barbosa, F J; Bonneau, P; Christo, S B; Dodge, G E; Dooling, T; Duncan, W S; Dytman, S A; Feuerbach, R; Gilfoyle, G P; Gyurjyan, V; Hicks, K H; Hicks, R S; Hyde-Wright, C E; Jacobs, G; Klein, A; Klein, F J; Kossov, M; Kuhn, S E; Magahiz, R A; Major, R W; Martin, C; McGuckin, T; McNabb, J; Miskimen, R A; Müller, J A; Niczyporuk, B B; O'Meara, J E; Qin, L M; Raue, B A; Robb, J; Roudot, F; Schumacher, R A; Tedeschi, D J; Thompson, R A; Tilles, D; Tuzel, W; Vansyoc, K; Vineyard, M F; Weinstein, L B; Wilkin, G R; Yegneswaran, A; Yun, J

    2000-01-01

    Experimental Hall B at Jefferson Laboratory houses the CEBAF Large Acceptance Spectrometer, the magnetic field of which is produced by a superconducting toroid. The six coils of this toroid divide the detector azimuthally into six sectors, each of which contains three large multi-layer drift chambers for tracking charged particles produced from a fixed target on the toroidal axis. Within the 18 drift chambers are a total of 35,148 individually instrumented hexagonal drift cells. The novel geometry of these chambers provides for good tracking resolution and efficiency, along with large acceptance. The design and construction challenges posed by these large-scale detectors are described, and detailed results are presented from in-beam measurements.

  7. Drift tubes of Linac 2

    CERN Multimedia

    CERN PhotoLab

    1977-01-01

    With the advent of the 800 MeV PS Booster in 1972, the original injector of the PS, a 50 MeV Alvarez-type proton linac, had reached its limits, in terms of intensity and stability. In 1973 one therefore decided to build a new linac (Linac 2), also with a drift-tube Alvarez structure and an energy of 50 MeV. It had a new Cockcroft-Walton preinjector with 750 keV, instead of the previous one with 500 keV. Linac 2 was put into service in 1980. The old Linac 1 was then used for the study of, and later operation with, various types of ions. This picture shows Linac 2 drift-tubes, suspended on stems coming from the top, in contrast to Linac 1, where the drift-tubes stood on stems coming from the bottom.

  8. Collisional drift fluid equations and implications for drift waves

    International Nuclear Information System (INIS)

    Pfirsch, Dieter; Correa-Restrepo, Dario

    1996-01-01

    The usual theoretical description of drift-wave turbulence (considered to be one possible cause of anomalous transport in a plasma), e.g. the Hasegawa-Wakatani theory, makes use of various approximations, the effects of which are extremely difficult to assess. This concerns in particular the conservation laws for energy and momentum. The latter law is important in relation to charge separation and the resulting electric fields, which are possibly related to the L-H transition. Energy conservation is crucial to the stability behaviour, it will be discussed by means of an example. New collisional multi-species drift-fluid equations were derived by a new method which yields, in a transparent way, conservation of energy and total angular momentum and the law for energy dissipation. Both electrostatic and electromagnetic field variations are considered. The only restriction involved is the validity of the drift approximation; in particular, there are no assumptions restricting the geometry of the system. The method is based primarily on a Lagrangian for dissipationless fluids in the drift approximation with isotropic pressures. The dissipative terms are introduced by adding corresponding terms to the ideal equations of motion and of the pressures. The equations of motion, of course, no longer result from a Lagrangian via Hamilton's principle. However, their relation to the ideal equations also implies a relation to the ideal Lagrangian, which can be used to advantage. Instead of introducing heat conduction one can also assume isothermal behaviour, e.g. T v (x) = constant. Assumptions of this kind are often made in the literature. The new method of introducing dissipation is not restricted to the present kind of theory; it can equally well be applied to theories such as multi-fluid theories without using the drift approximation of the present paper. (author)

  9. Modeling and optimizing of the random atomic spin gyroscope drift based on the atomic spin gyroscope

    Energy Technology Data Exchange (ETDEWEB)

    Quan, Wei; Lv, Lin, E-mail: lvlinlch1990@163.com; Liu, Baiqi [School of Instrument Science and Opto-Electronics Engineering, Beihang University, Beijing 100191 (China)

    2014-11-15

    In order to improve the atom spin gyroscope's operational accuracy and compensate the random error caused by the nonlinear and weak-stability characteristic of the random atomic spin gyroscope (ASG) drift, the hybrid random drift error model based on autoregressive (AR) and genetic programming (GP) + genetic algorithm (GA) technique is established. The time series of random ASG drift is taken as the study object. The time series of random ASG drift is acquired by analyzing and preprocessing the measured data of ASG. The linear section model is established based on AR technique. After that, the nonlinear section model is built based on GP technique and GA is used to optimize the coefficients of the mathematic expression acquired by GP in order to obtain a more accurate model. The simulation result indicates that this hybrid model can effectively reflect the characteristics of the ASG's random drift. The square error of the ASG's random drift is reduced by 92.40%. Comparing with the AR technique and the GP + GA technique, the random drift is reduced by 9.34% and 5.06%, respectively. The hybrid modeling method can effectively compensate the ASG's random drift and improve the stability of the system.

  10. Review of semiconductor drift detectors

    Science.gov (United States)

    Gatti, Emilio; Rehak, Pavel

    2005-04-01

    A short review of semiconductor drift detectors is given. The emphasis is given to detectors intended for tracking of fast charged particles for experiments in particle physics and high energy heavy-ion physics. The use and performance of this kind of detector in past, present and future experiments is described together with the experience learned during the design, production and data taking phases.

  11. Job satisfaction and preference drift.

    NARCIS (Netherlands)

    Maassen van den Brink, H.; Groot, W.J.N.

    1999-01-01

    Most empirical studies do not find that higher wages lead to more job satisfaction. In this paper we argue that the insignificant effect of wages on job satisfaction is due to preference drift. We adapt the standard ordered response model to allow for preference shifts. The empirical results support

  12. The Continental Drift Convection Cell

    Science.gov (United States)

    Whitehead, J. A.; Behn, M. D.

    2014-12-01

    Continents on Earth periodically assemble to form supercontinents, and then break up again into smaller continental blocks (the Wilson Cycle). Highly developed but realistic numerical models cannot resolve if continents respond passively to mantle convection or whether they modulate flow. Our simplified numerical model addresses this problem: A thermally insulating continent floats on a stress-free surface for infinite Prandtl number cellular convection with constant material properties in a chamber 8 times longer than its depth. The continent moves back and forth across the chamber driven by a "continental drift convection cell" of a form not previously described. Subduction exists at the upstream end with cold slabs dipping at an angle beneath the moving continent. Fluid moves with the continent in the upper region of this cell with return flow near the bottom. Many continent/subduction regions on Earth have these features. The drifting cell enhances vertical heat transport by approximately 30% compared to a fixed continent, especially at the core-mantle boundary, and significantly decreases lateral mantle temperature differences. However, continent drift or fixity has smaller effects on profiles of horizontally averaged temperature. Although calculations are done at Rayleigh numbers lower than expected for Earth's mantle (2x105 and 106), the drift speed extrapolates to reasonable Wilson Cycle speeds for larger Ra.

  13. First results from the DRIFT-1 detector

    International Nuclear Information System (INIS)

    Ayad, R.; Kirkpatrick, J.; Lawson, T.B.; Martoff, C.J.; Morgan, B.; Paling, S.M.; Snowden-Ifft, D.P.; Spooner, N.J.C.

    2003-01-01

    DRIFT-I is the world's first WIMP dark matter detector with sensitivity to the direction of nuclear recoils. This article discusses the DRIFT-I detector, and presents some preliminary data from underground engineering runs

  14. Drift Chambers detectors; Detectores de deriva

    Energy Technology Data Exchange (ETDEWEB)

    Duran, I.; Martinez laso, L.

    1989-07-01

    We present here a review of High Energy Physics detectors based on drift chambers. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysed, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author) 115 refs.

  15. Air Quality and Health Benefits of China's Recent Stringent Environmental Policy

    Science.gov (United States)

    Zheng, Y.; Xue, T.; Zhang, Q.; Geng, G.; He, K.

    2016-12-01

    Aggressive emission control measures were taken by China's central and local governments after the promulgation of the "Air Pollution Prevention and Control Action Plan" in 2013. We evaluated the air quality and health benefits of this ever most stringent air pollution control policy during 2013-2015 by utilizing a two-stage data fusion model and newly-developed cause-specific integrated exposure-response functions (IER) developed for the Global Burden of Disease (GBD). The two-stage data fusion model predicts spatiotemporal continuous PM2.5 (particulate matter with aerodynamic diameter less than 2.5 µm) concentrations by integrating satellite-derived aerosol optical depth (AOD) measurements, PM2.5 concentrations from measurement and air quality model, and other ancillary information. During the years of analysis, PM2.5 concentration dropped significantly on national average and over heavily polluted regions as identified by Mann-Kendall analysis. The national PM2.5-attributable mortality decreased by 72.8 (95% CI: 59.4, 85.2) thousand (6%) from 1.23 (95% CI: 1.06, 1.39) million in 2013 to 1.15 (95% CI: 0.98, 1.31) million in 2015 due to considerable reduction (i.e. 18%) of population-weighted PM2.5 from 61.4 to 50.5 µg/m3. Meteorological variations between 2013 and 2015 were estimated to raise the PM2.5 levels by 0.24 µg/m3 and national mortality by 2.1 (95% CI: 1.6, 2.6) thousand through sensitivity tests, which implies the dominant role of anthropogenic impacts on PM2.5 abatement and attributable mortality reduction. Our study affirms the effectiveness of China's recent air quality policy, however, due to the possible supralinear shape of C-R functions, health benefits induced by air quality improvement in these years are limited. We therefore appeal for continuous implementation of current policies and further stringent measures from both air quality improvement and public health protection perspectives.

  16. A Pascalian lateral drift sensor

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, H., E-mail: hendrik.jansen@desy.de

    2016-09-21

    A novel concept of a layer-wise produced semiconductor sensor for precise particle tracking is proposed herein. In contrast to common semiconductor sensors, local regions with increased doping concentration deep in the bulk termed charge guides increase the lateral drift of free charges on their way to the read-out electrode. This lateral drift enables charge sharing independent of the incident position of the traversing particle. With a regular grid of charge guides the lateral charge distribution resembles a normalised Pascal's triangle for particles that are stopped in depths lower than the depth of the first layer of the charge guides. For minimum ionising particles a sum of binomial distributions describes the lateral charge distribution. This concept decouples the achievable sensor resolution from the pitch size as the characteristic length is replaced by the lateral distance of the charge guides.

  17. Nonlinear evolution of drift instabilities

    International Nuclear Information System (INIS)

    Lee, W.W.; Krommes, J.A.; Oberman, C.R.; Smith, R.A.

    1984-01-01

    The nonlinear evolution of collisionless drift instabilities in a shear-free magnetic field has been studied by means of gyrokinetic particle simulation as well as numerical integration of model mode-coupling equations. The purpose of the investigation is to identify relevant nonlinear mechanisms responsible for the steady-state drift wave fluctuations. It is found that the saturation of the instability is mainly caused by the nonlinear E x B convection of the resonant electrons and their associated velocity space nonlinearity. The latter also induces energy exchange between the competing modes, which, in turn, gives rise to enhanced diffusion. The nonlinear E x B convection of the ions, which contributes to the nonlinear frequency shift, is also an important ingredient for the saturation

  18. ATLAS Muon Drift Tube Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Arai, Y [KEK, High Energy Accelerator Research Organisation, Tsukuba (Japan); Ball, B; Chapman, J W; Dai, T; Ferretti, C; Gregory, J [University of Michigan, Department of Physics, Ann Arbor, MI (United States); Beretta, M [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Boterenbrood, H; Jansweijer, P P M [Nikhef National Institute for Subatomic Physics, Amsterdam (Netherlands); Brandenburg, G W; Fries, T; Costa, J Guimaraes da; Harder, S; Huth, J [Harvard University, Laboratory for Particle Physics and Cosmology, Cambridge, MA (United States); Ceradini, F [INFN Roma Tre and Universita Roma Tre, Dipartimento di Fisica, Roma (Italy); Hazen, E [Boston University, Physics Department, Boston, MA (United States); Kirsch, L E [Brandeis University, Department of Physics, Waltham, MA (United States); Koenig, A C [Radboud University Nijmegen/Nikhef, Dept. of Exp. High Energy Physics, Nijmegen (Netherlands); Lanza, A [INFN Pavia, Pavia (Italy); Mikenberg, G [Weizmann Institute of Science, Department of Particle Physics, Rehovot (Israel)], E-mail: brandenburg@physics.harvard.edu (and others)

    2008-09-15

    This paper describes the electronics used for the ATLAS monitored drift tube (MDT) chambers. These chambers are the main component of the precision tracking system in the ATLAS muon spectrometer. The MDT detector system consists of 1,150 chambers containing a total of 354,000 drift tubes. It is capable of measuring the sagitta of muon tracks to an accuracy of 60 {mu}m, which corresponds to a momentum accuracy of about 10% at p{sub T}= 1 TeV. The design and performance of the MDT readout electronics as well as the electronics for controlling, monitoring and powering the detector will be discussed. These electronics have been extensively tested under simulated running conditions and have undergone radiation testing certifying them for more than 10 years of LHC operation. They are now installed on the ATLAS detector and are operating during cosmic ray commissioning runs.

  19. ATLAS Muon Drift Tube Electronics

    CERN Document Server

    Arai, Y; Beretta, M; Boterenbrood, H; Brandenburg, G W; Ceradini, F; Chapman, J W; Dai, T; Ferretti, C; Fries, T; Gregory, J; Guimarães da Costa, J; Harder, S; Hazen, E; Huth, J; Jansweijer, P P M; Kirsch, L E; König, A C; Lanza, A; Mikenberg, G; Oliver, J; Posch, C; Richter, R; Riegler, W; Spiriti, E; Taylor, F E; Vermeulen, J; Wadsworth, B; Wijnen, T A M

    2008-01-01

    This paper describes the electronics used for the ATLAS monitored drift tube (MDT) chambers. These chambers are the main component of the precision tracking system in the ATLAS muon spectrometer. The MDT detector system consists of 1,150 chambers containing a total of 354,000 drift tubes. It is capable of measuring the sagitta of muon tracks to an accuracy of 60 microns, which corresponds to a momentum accuracy of about 10% at pT = 1 TeV. The design and performance of the MDT readout electronics as well as the electronics for controlling, monitoring and powering the detector will be discussed. These electronics have been extensively tested under simulated running conditions and have undergone radiation testing certifying them for more than 10 years of LHC operation. They are now installed on the ATLAS detector and are operating during cosmic ray commissioning runs.

  20. Diffusion approximations for one-locus multi-allele kin selection, mutation and random drift in group-structured populations: a unifying approach to selection models in population genetics.

    Science.gov (United States)

    Lessard, Sabin

    2009-11-01

    Diffusion approximations are ascertained from a two-time-scale argument in the case of a group-structured diploid population with scaled viability parameters depending on the individual genotype and the group type at a single multi-allelic locus under recurrent mutation, and applied to the case of random pairwise interactions within groups. The main step consists in proving global and uniform convergence of the distribution of the group types in an infinite population in the absence of selection and mutation, using a coalescent approach. An inclusive fitness formulation with coefficient of relatedness between a focal individual J affecting the reproductive success of an individual I, defined as the expected fraction of genes in I that are identical by descent to one or more genes in J in a neutral infinite population, given that J is allozygous or autozygous, yields the correct selection drift functions. These are analogous to the selection drift functions obtained with pure viability selection in a population with inbreeding. They give the changes of the allele frequencies in an infinite population without mutation that correspond to the replicator equation with fitness matrix expressed as a linear combination of a symmetric matrix for allozygous individuals and a rank-one matrix for autozygous individuals. In the case of no inbreeding, the mean inclusive fitness is a strict Lyapunov function with respect to this deterministic dynamics. Connections are made between dispersal with exact replacement (proportional dispersal), uniform dispersal, and local extinction and recolonization. The timing of dispersal (before or after selection, before or after mating) is shown to have an effect on group competition and the effective population size.

  1. Genetics

    Science.gov (United States)

    ... Likelihood of getting certain diseases Mental abilities Natural talents An abnormal trait (anomaly) that is passed down ... one of them has a genetic disorder. Information Human beings have cells with 46 chromosomes . These consist ...

  2. Journal of Genetics | News

    Indian Academy of Sciences (India)

    We analysed the relative roles of selection and genetic drift in maintaining genetic variation in laboratory populations of Drosophila. We suggest that rare, favourable genetic variants in our laboratory populations have a high chance of being lost if their fitness effect is weak, e.g. 1% or less. However, if the fitness effect of this ...

  3. Does dishonesty really invite third-party punishment? Results of a more stringent test.

    Science.gov (United States)

    Konishi, Naoki; Ohtsubo, Yohsuke

    2015-05-01

    Many experiments have demonstrated that people are willing to incur cost to punish norm violators even when they are not directly harmed by the violation. Such altruistic third-party punishment is often considered an evolutionary underpinning of large-scale human cooperation. However, some scholars argue that previously demonstrated altruistic third-party punishment against fairness-norm violations may be an experimental artefact. For example, envy-driven retaliatory behaviour (i.e. spite) towards better-off unfair game players may be misidentified as altruistic punishment. Indeed, a recent experiment demonstrated that participants ceased to inflict third-party punishment against an unfair player once a series of key methodological problems were systematically controlled for. Noticing that a previous finding regarding apparently altruistic third-party punishment against honesty-norm violations may have been subject to methodological issues, we used a different and what we consider to be a more sound design to evaluate these findings. Third-party punishment against dishonest players withstood this more stringent test. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  4. Emission reductions in transition economies: A result of output contraction or more stringent environmental policy?

    Energy Technology Data Exchange (ETDEWEB)

    Zugravu, N.; Millock, K. [University Paris 1 Pantheon-Sorbonne (France); Duchene, G. [University Paris 12, Creteil (France)

    2007-07-01

    Countries in Central and Eastern Europe significantly reduced their CO{sub 2} emissions between 1996 and 2001. Was this emission reduction just the fortuitous result of the major economic transformation undergone by those countries in the transition away from a centralized plan economy? Or is the emission reduction rather a result of more stringent environmental policy? The objective of the article is to answer this question through a model of the relation between environmental quality and enforcement, on the one hand, and environmental quality and economic growth, on the other hand. The authors develop structural equations for the demand (emissions) and supply (environmental stringency) of pollution. The supply equation takes into account the institutional quality of the country (control of corruption and political stability) as well as consumer preferences for environmental quality, as proxied by per capita revenue and unemployment. The system is estimated by three stage least squares on a sample of three groups of countries for comparative analysis: Central and Eastern European countries, Western European countries, and emerging economies. The results indicate that, all else equal, the scale effect on its own would have increased industrial CO{sub 2} emissions in the Central and Eastern European countries in the sample by 44.6% between 1996 and 2001. The composition effect accounted for a corresponding reduction in emissions by 16%. The technique effect had the largest marginal impact, corresponding to a 37.4% reduction in emissions.

  5. Genetics

    International Nuclear Information System (INIS)

    Hubitschek, H.E.

    1975-01-01

    Progress is reported on the following research projects: genetic effects of high LET radiations; genetic regulation, alteration, and repair; chromosome replication and the division cycle of Escherichia coli; effects of radioisotope decay in the DNA of microorganisms; initiation and termination of DNA replication in Bacillus subtilis; mutagenesis in mouse myeloma cells; lethal and mutagenic effects of near-uv radiation; effect of 8-methoxypsoralen on photodynamic lethality and mutagenicity in Escherichia coli; DNA repair of the lethal effects of far-uv; and near uv irradiation of bacterial cells

  6. The rapidly evolving centromere-specific histone has stringent functional requirements in Arabidopsis thaliana.

    Science.gov (United States)

    Ravi, Maruthachalam; Kwong, Pak N; Menorca, Ron M G; Valencia, Joel T; Ramahi, Joseph S; Stewart, Jodi L; Tran, Robert K; Sundaresan, Venkatesan; Comai, Luca; Chan, Simon W-L

    2010-10-01

    Centromeres control chromosome inheritance in eukaryotes, yet their DNA structure and primary sequence are hypervariable. Most animals and plants have megabases of tandem repeats at their centromeres, unlike yeast with unique centromere sequences. Centromere function requires the centromere-specific histone CENH3 (CENP-A in human), which replaces histone H3 in centromeric nucleosomes. CENH3 evolves rapidly, particularly in its N-terminal tail domain. A portion of the CENH3 histone-fold domain, the CENP-A targeting domain (CATD), has been previously shown to confer kinetochore localization and centromere function when swapped into human H3. Furthermore, CENP-A in human cells can be functionally replaced by CENH3 from distantly related organisms including Saccharomyces cerevisiae. We have used cenh3-1 (a null mutant in Arabidopsis thaliana) to replace endogenous CENH3 with GFP-tagged variants. A H3.3 tail domain-CENH3 histone-fold domain chimera rescued viability of cenh3-1, but CENH3's lacking a tail domain were nonfunctional. In contrast to human results, H3 containing the A. thaliana CATD cannot complement cenh3-1. GFP-CENH3 from the sister species A. arenosa functionally replaces A. thaliana CENH3. GFP-CENH3 from the close relative Brassica rapa was targeted to centromeres, but did not complement cenh3-1, indicating that kinetochore localization and centromere function can be uncoupled. We conclude that CENH3 function in A. thaliana, an organism with large tandem repeat centromeres, has stringent requirements for functional complementation in mitosis.

  7. Genetics

    DEFF Research Database (Denmark)

    Christensen, Kaare; McGue, Matt

    2016-01-01

    The sequenced genomes of individuals aged ≥80 years, who were highly educated, self-referred volunteers and with no self-reported chronic diseases were compared to young controls. In these data, healthy ageing is a distinct phenotype from exceptional longevity and genetic factors that protect...

  8. Kinetic theory of drift waves

    International Nuclear Information System (INIS)

    Vlad, G.

    1988-01-01

    The linear stability of the electrostatic drift waves in slab geometry has been studied analytically and numerically. The effects of magnetic field with shear, of the finite Larmor radius, of an electron streaming, of a temperature gradient and of collisions have been retained. The analytical solution has been obtained using the matched asymptotic expansion technique, and an expression for the critical streaming parameter has been derived. Finally, assuming that the transport in the Reversed Field Pinches is dominated by this instability, a scaling law for the temperature in such machine is derived

  9. Drift vortices in continuous media

    International Nuclear Information System (INIS)

    Chernousenko, V.M.; Chernenko, I.V.; Chernyshenko, S.V.

    1989-01-01

    The work is devoted to investigation into the problems of large-scale cortex drift and generation in continuous media based on the solution of notably non-linear differential equations. Using the capability of the modern computer technique it is possible to consider a series of cases with regard to medium viscosity and its inhomogeneity and with regard to three-dimensional vortex nature. Based on the solutions obtained the large-scale steady-state vortex generation processes are considered. The results can be used when studying non-linear phenomena in plasma and processes of substance and energy transfer in non-equilibrium media. 16 refs.; 5 figs

  10. Drift waves in a stellarator

    International Nuclear Information System (INIS)

    Bhattacharjee, A.; Sedlak, J.E.; Similon, P.L.; Rosenbluth, M.N.; Ross, D.W.

    1982-11-01

    We investigate the eigenmode structure of drift waves in a straight stellarator using the ballooning mode formalism. The electrons are assumed to be adiabatic and the ions constitute a cold, magnetized fluid. The effective potential has an overall parabolic envelope but is modulated strongly by helical ripples along B. We have found two classes of solutions: those that are strongly localized in local helical wells, and those that are weakly localized and have broad spatial extent. The weakly localized modes decay spatially due to the existence of Mathieu resonances between the periods of the eigenfunction and the effective potential

  11. Managing Capacity by Drift Control

    OpenAIRE

    Ormeci Matoglu, Melda; Vande Vate, John

    2009-01-01

    We model the problem of managing capacity in a build-to-order environment as a Brownian drift control problem and seek a policy that minimizes the long-term average cost. We assume the controller can, at some cost, shift the processing rate among a finite set of alternatives by, for example, adding or removing staff, increasing or reducing the number of shifts or opening or closing production lines. The controller incurs a cost for capacity per unit time and a delay cost that reflects th...

  12. Experimental work on drift chambers

    International Nuclear Information System (INIS)

    Alcaraz, J.; Duran, I.; Gonzalez, E.; Martinez-Laso, L.; Olmos, P.

    1989-01-01

    An experimental work made on drift chambers is described in two chapters. In the firt chapter we present the description of the experimental installation used, as well as some details on the data adquisition systems and the characteristics on three ways used for calibration proposes (cosmic muons, β radiation and test beam using SPS at CERN facilities). The second chapter describes the defferent prototypes studied. The experimental set up and the analysis are given. Some results are discussed. The magnetic field effect is also studied. (Author)

  13. Spiral biasing adaptor for use in Si drift detectors and Si drift detector arrays

    Science.gov (United States)

    Li, Zheng; Chen, Wei

    2016-07-05

    A drift detector array, preferably a silicon drift detector (SDD) array, that uses a low current biasing adaptor is disclosed. The biasing adaptor is customizable for any desired geometry of the drift detector single cell with minimum drift time of carriers. The biasing adaptor has spiral shaped ion-implants that generate the desired voltage profile. The biasing adaptor can be processed on the same wafer as the drift detector array and only one biasing adaptor chip/side is needed for one drift detector array to generate the voltage profiles on the front side and back side of the detector array.

  14. Limits to Drift Chamber Resolution

    CERN Document Server

    Riegler, Werner

    1998-01-01

    ATLAS (A Large Toroidal LHC Apparatus) will be a general-purpose experiment at the Large Hadron Collider that will be operational at CERN in the year 2004. The ATLAS muon spectrometer aims for a momentum resolution of 10% for a transverse momentum of pT=1TeV. The precision tracking devices in the muon system will be high pressure drift tubes (MDTs) with a single wire resolution of 1100 chambers covering an area of ≈ 2500m2. The high counting rates in the spectrometer as well as the aim for excellent spatial resolution and high efficiency put severe constraints on the MDT operating parameters. This work describes a detailed study of all the resolution limiting factors in the ATLAS environment. A ’full chain’ simulation of the MDT response to photons and charged particles as well as quantitative comparisons with measurements was performed. The good agreement between simulation and measurements resulted in a profound understanding of the drift chamber processes and the individual contributions to the spat...

  15. Investigations of SPS orbit drifts

    CERN Document Server

    Drøsdal, L; Cornelis, K; Goddard, B; Kain, V; Meddahi, M; Wenninger, J; Gianfelice-Wendt, E

    2014-01-01

    The LHC is filled from the last pre-injector, the Super Proton Synchrotron (SPS), via two 3 km long transfer lines, TI 2 and TI 8. Over the LHC injection processes, a drift of the beam trajectories has been observed in TI 2 and TI 8, requiring regular correction of the trajectories, in order to ensure clean injection into the LHC. Investigations of the trajectory variations in the transfer lines showed that the main source of short term trajectory drifts are current variations of the SPS extraction septa (MSE). The stability of the power converters has been improved, but the variations are still present and further improvements are being investigated. The stability over a longer period of time cannot be explained by this source alone. The analysis of trajectory variations shows that there are also slow variations in the SPS closed orbit at extraction. A set of SPS orbit measurements has been saved and analysed. These observations will be used together with simulations and observed field errors to locate the s...

  16. Drift-time measurement electronics

    International Nuclear Information System (INIS)

    Pernicka, M.

    1978-01-01

    The aim of the construction was to improve the time resolution without using the facility of time stretching, to have a fast read-out possibility, and to be still cheaper in price in comparison to other systems. A possibility was thus foreseen for using the firm Fairchild. These integrated circuits (IC) have, for example, a propagation delay of 0.75 ns for a gate. One can expect therefore less time jitter and less time difference between the different inputs. Furthermore this IC offers a greater flexibility and therefore the number of ICs decreases and distances become smaller. Working with clock frequencies up to 166.6 MHz is easily possible without running into timing problems. On the other hand, to make full use of the advantages of this IC, it was necessary to build the print as a multilayer. The only risk could be in the use of a completely new product. A further aim was to build for this system a second type of drift-time module with a short time range for measuring drift time and pulse length in rotated multiwire proportional chambers. A brief outline of the specifications of the different modules is given in table 1. (Auth.)

  17. Oscilação genética em populações submetidas a métodos de seleção tradicionais e associados a marcadores moleculares Genetic drift in populations under traditional and marker assisted selection

    Directory of Open Access Journals (Sweden)

    Paulo Luiz Souza Carneiro

    2006-02-01

    Full Text Available Com o objetivo de avaliar o efeito da oscilação genética em populações sob seleção com diferentes tamanhos efetivos, foram simulados dados utilizando-se o programa GENESYS. A seleção foi praticada durante 20 gerações consecutivas, com base na seleção individual (SI e nos valores genéticos preditos pelo BLUP Clássico (BLUP e pelo BLUP Marcadores (BLUPM, com 30 repetições. A matriz de similaridade adotada no BLUP Marcadores foi obtida utilizando-se 100 marcadores moleculares do tipo microssatélite, por meio de um coeficiente de similaridade correspondente à distância euclidiana média para dados quantitativos. Foram simuladas seis populações de seleção, correspondendo a dois tamanhos efetivos (18,18 e 66,66 e três sistemas de acasalamento dos reprodutores selecionados (reprodutores acasalados ao acaso, exclusão de irmãos completos e exclusão de irmãos completos e meio-irmãos. O parâmetro avaliado foi o valor fenotípico médio. Observou-se grande variação nos valores fenotípicos obtidos pelos métodos, em razão da oscilação genética, principalmente para a seleção baseada nos valores genéticos preditos pelo BLUP e BLUPM e para as populações com tamanho efetivo menor (18,18. Os resultados sugerem que, em programas de melhoramento que utilizam pequenas populações sob seleção, os resultados podem ser influenciados pela oscilação genética, podendo apresentar grandes variações nos ganhos genéticos.The effect of genetic drift in populations under selection with different effective sizes was evaluated using data simulated by the GENESYS program. Selection was applied during 20 generations based on Individual selection (IS using breeding values predicted by classical best linear unbiased prediction (BLUP and BLUP associated with molecular markers (BLUPM. The similarity matrix used in BLUPM was obtained by simulation of 100 micro-satellites markers (simple sequence repeats using a similarity coefficient

  18. Stringently Defined Otitis Prone Children Demonstrate Deficient Naturally Induced Mucosal Antibody Response to Moraxella catarrhalis Proteins

    Directory of Open Access Journals (Sweden)

    Dabin Ren

    2017-08-01

    Full Text Available Moraxella catarrhalis (Mcat is a prominent mucosal pathogen causing acute otitis media (AOM. We studied Mcat nasopharyngeal (NP colonization, AOM frequency and mucosal antibody responses to four vaccine candidate Mcat proteins: outer membrane protein (OMP CD, oligopeptide permease (Opp A, hemagglutinin (Hag, and Pilin A clade 2 (PilA2 from stringently defined otitis prone (sOP children, who experience the greatest burden of disease, compared to non-otitis prone (NOP children. sOP children had higher NP colonization of Mcat (30 vs. 22%, P = 0.0003 and Mcat-caused AOM rates (49 vs. 24%, P < 0.0001 than NOP children. Natural acquisition of mucosal antibodies to Mcat proteins OMP CD (IgG, P < 0.0001, OppA (IgG, P = 0.018, Hag (IgG and IgA, both P < 0.0001, and PilA2 (IgA, P < 0.0001 was lower in sOP than NOP children. Higher levels of mucosal IgG to Hag (P = 0.039 and PilA2 (P = 0.0076, and IgA to OMP CD (P = 0.010, OppA (P = 0.030, and PilA2 (P = 0.043 were associated with lower carriage of Mcat in NOP but not sOP children. Higher levels of mucosal IgG to OMP CD (P = 0.0070 and Hag (P = 0.0003, and IgA to Hag (P = 0.0067 at asymptomatic colonization than those at onset of AOM were associated with significantly lower rate of Mcat NP colonization progressing to AOM in NOP compared to sOP children (3 vs. 26%, P < 0.0001. In conclusion, sOP children had a diminished mucosal antibody response to Mcat proteins, which was associated with higher frequencies of asymptomatic NP colonization and NP colonization progressing to Mcat-caused AOM. Enhancing Mcat antigen-specific mucosal immune responses to levels higher than achieved by natural exposure will be necessary to prevent AOM in sOP children.

  19. Electron injection in semiconductor drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.; Longoni, A.; Sampietro, M.; Castoldi, A.; Vacchi, A.

    1990-01-01

    The paper reports the first successful results of a simple MOS structure to inject electrons at a given position in Silicon Drift Detectors. The structure allows on-line calibration of the drift velocity of electrons within the detector. The calibration is a practical method to trace the temperature dependence of the electron mobility. Several of these injection structures can be implemented in silicon drift detectors without additional steps in the fabrication process

  20. The large cylindrical drift chamber of TASSO

    International Nuclear Information System (INIS)

    Boerner, H.; Fischer, H.M.; Hartmann, H.; Loehr, B.; Wollstadt, M.; Fohrmann, R.; Schmueser, P.; Cassel, D.G.; Koetz, U.; Kowalski, H.

    1980-03-01

    We have built and operated a large cylindrical drift chamber for the TASSO experiment at the DESY storage ring, PETRA. The chamber has a length of 3.5 m, a diameter of 2.5 m, and a total of 2340 drift cells. The cells are arranged in 15 concentric layers such that tracks can be reconstructed in three dimensions. A spatial resolution of 220 μm has been achieved for tracks of normal incidence on the drift cells. (orig.)

  1. Drift chamber tracking with neural networks

    International Nuclear Information System (INIS)

    Lindsey, C.S.; Denby, B.; Haggerty, H.

    1992-10-01

    We discuss drift chamber tracking with a commercial log VLSI neural network chip. Voltages proportional to the drift times in a 4-layer drift chamber were presented to the Intel ETANN chip. The network was trained to provide the intercept and slope of straight tracks traversing the chamber. The outputs were recorded and later compared off line to conventional track fits. Two types of network architectures were studied. Applications of neural network tracking to high energy physics detector triggers is discussed

  2. Electron drift time in silicon drift detectors: A technique for high precision measurement of electron drift mobility

    International Nuclear Information System (INIS)

    Castoldi, A.; Rehak, P.

    1995-01-01

    This paper presents a precise absolute measurement of the drift velocity and mobility of electrons in high resistivity silicon at room temperature. The electron velocity is obtained from the differential measurement of the drift time of an electron cloud in a silicon drift detector. The main features of the transport scheme of this class of detectors are: the high uniformity of the electron motion, the transport of the signal electrons entirely contained in the high-purity bulk, the low noise timing due to the very small anode capacitance (typical value 100 fF), and the possibility to measure different drift distances, up to the wafer diameter, in the same semiconductor sample. These features make the silicon drift detector an optimal device for high precision measurements of carrier drift properties. The electron drift velocity and mobility in a 10 kΩ cm NTD n-type silicon wafer have been measured as a function of the electric field in the range of possible operation of a typical drift detector (167--633 V/cm). The electron ohmic mobility is found to be 1394 cm 2 /V s. The measurement precision is better than 1%. copyright 1995 American Institute of Physics

  3. Seepage Model for PA Including Drift Collapse

    International Nuclear Information System (INIS)

    Li, G.; Tsang, C.

    2000-01-01

    The purpose of this Analysis/Model Report (AMR) is to document the predictions and analysis performed using the Seepage Model for Performance Assessment (PA) and the Disturbed Drift Seepage Submodel for both the Topopah Spring middle nonlithophysal and lower lithophysal lithostratigraphic units at Yucca Mountain. These results will be used by PA to develop the probability distribution of water seepage into waste-emplacement drifts at Yucca Mountain, Nevada, as part of the evaluation of the long term performance of the potential repository. This AMR is in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (CRWMS M andO 2000 [153447]). This purpose is accomplished by performing numerical simulations with stochastic representations of hydrological properties, using the Seepage Model for PA, and evaluating the effects of an alternative drift geometry representing a partially collapsed drift using the Disturbed Drift Seepage Submodel. Seepage of water into waste-emplacement drifts is considered one of the principal factors having the greatest impact of long-term safety of the repository system (CRWMS M andO 2000 [153225], Table 4-1). This AMR supports the analysis and simulation that are used by PA to develop the probability distribution of water seepage into drift, and is therefore a model of primary (Level 1) importance (AP-3.15Q, ''Managing Technical Product Inputs''). The intended purpose of the Seepage Model for PA is to support: (1) PA; (2) Abstraction of Drift-Scale Seepage; and (3) Unsaturated Zone (UZ) Flow and Transport Process Model Report (PMR). Seepage into drifts is evaluated by applying numerical models with stochastic representations of hydrological properties and performing flow simulations with multiple realizations of the permeability field around the drift. The Seepage Model for PA uses the distribution of permeabilities derived from air injection testing in niches and in the cross drift to

  4. Silicon drift detectors with the drift field induced by pureB-coated trenches

    NARCIS (Netherlands)

    Nanver, Lis Karen; Kneževi´c, Tihomir; Suligoj, Tomislav

    2016-01-01

    Junction formation in deep trenches is proposed as a new means of creating a built-in drift field in silicon drift detectors (SDDs). The potential performance of this trenched drift detector (TDD) was investigated analytically and through simulations, and compared to simulations of conventional

  5. Clumps in drift wave turbulence

    DEFF Research Database (Denmark)

    Pecseli, H. L.; Mikkelsen, Torben

    1986-01-01

    In a statistical analysis pair correlation of particles is eventually destroyed by small scale fluctuations giving rise to relative particle diffusion. However, in any one given realization of the statistical ensemble particles may remain correlated in certain regions of space. A perfectly frozen......, two-dimensional random flow serves as a particularly simple illustration. For this case particles can be trapped for all times in a local vortex (macro-clump). A small test-cloud of particles (micro-clump) chosen arbitrarily in a realization will on the other hand expand on average. A formulation...... is proposed in terms of conditional eddies, in order to discriminate turbulent flows where macro-clumps may be observed. The analysis is illustrated by results from experimental investigations of strongly turbulent, resistive drift-wave fluctuations. The related problem for electrostatic turbulence...

  6. Autoresonant control of drift waves

    DEFF Research Database (Denmark)

    Shagalov, A.G.; Rasmussen, Jens Juul; Naulin, Volker

    2017-01-01

    The control of nonlinear drift waves in a magnetized plasmas column has been investigated. The studies are based on the Hasegawa–Mima model, which is solved on a disk domain with radial inhomogeneity of the plasma density. The system is forced by a rotating potential with varying frequency defined...... on the boundary. To excite and control the waves we apply the autoresonant effect, taking place when the amplitude of the forcing exceeds a threshold value and the waves are phase-locked with the forcing. We demonstrate that the autoresonant approach is applicable for excitation of a range of steady nonlinear...... waves of the lowest azimuthal mode numbers and for controlling their amplitudes and phases. We also demonstrate the excitation of zonal flows (m = 0 modes), which are controlled via the forced modes....

  7. Single wire drift chamber design

    Energy Technology Data Exchange (ETDEWEB)

    Krider, J.

    1987-03-30

    This report summarizes the design and prototype tests of single wire drift chambers to be used in Fermilab test beam lines. The goal is to build simple, reliable detectors which require a minimum of electronics. Spatial resolution should match the 300 ..mu..m rms resolution of the 1 mm proportional chambers that they will replace. The detectors will be used in beams with particle rates up to 20 KHz. Single track efficiency should be at least 99%. The first application will be in the MT beamline, which has been designed for calibration of CDF detectors. A set of four x-y modules will be used to track and measure the momentum of beam particles.

  8. Direct-to-physician and direct-to-consumer advertising: Time to have stringent regulations.

    Science.gov (United States)

    Kannan, S; Gowri, S; Tyagi, V; Kohli, S; Jain, R; Kapil, P; Bhardwaj, A

    2015-01-01

    the opinion regarding DTCA, 69.9% physicians had a patient discussing DTCA that was clinically inappropriate. One hundred (64.5%) out of 155 physicians opined that DTCA encourage patients to attend physicians regarding preventive healthcare. On the contrary, 82/155 (52.9%) physicians felt that DTCA would damage the same. Similarly, 69 out of the total 100 patients felt that drug advertisements aid them to have better discussions with their treating physicians. Surprisingly, a large majority (91/100) were of the opinion that only safe drugs are allowed to be advertised. To conclude, from the findings of this study both the physicians and patients should be cautious and not overzealous while dealing with drug advertisements or promotional literature. More stringent scrutiny and issue of WLs or blacklisting of indulging pharmaceutical companies are mandatory by the regulatory agency to contain the same.

  9. Peering beyond the horizon with standard sirens and redshift drift

    Science.gov (United States)

    Jimenez, Raul; Raccanelli, Alvise; Verde, Licia; Matarrese, Sabino

    2018-04-01

    An interesting test on the nature of the Universe is to measure the global spatial curvature of the metric in a model independent way, at a level of |Ωk|<10‑4, or, if possible, at the cosmic variance level of the amplitude of the CMB fluctuations |Ωk|≈10‑5. A limit of |Ωk|<10‑4 would yield stringent tests on several models of inflation. Further, improving the constraint by an order of magnitude would help in reducing "model confusion" in standard parameter estimation. Moreover, if the curvature is measured to be at the value of the amplitude of the CMB fluctuations, it would offer a powerful test on the inflationary paradigm and would indicate that our Universe must be significantly larger than the current horizon. On the contrary, in the context of standard inflation, measuring a value above CMB fluctuations will lead us to conclude that the Universe is not much larger than the current observed horizon; this can also be interpreted as the presence of large fluctuations outside the horizon. However, it has proven difficult, so far, to find observables that can achieve such level of accuracy, and, most of all, be model-independent. Here we propose a method that can in principle achieve that; this is done by making minimal assumptions and using distance probes that are cosmology-independent: gravitational waves, redshift drift and cosmic chronometers. We discuss what kind of observations are needed in principle to achieve the desired accuracy.

  10. Evolution: drift will tear us apart.

    Science.gov (United States)

    Maderspacher, Florian

    2012-11-06

    That the widely scattered geographical distribution of some animals could be due to continental drift is a neat idea. Now, cave animals provide evidence for extreme long-term persistence on continents drifting apart. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Suppressing drift chamber diffusion without magnetic field

    International Nuclear Information System (INIS)

    Martoff, C.J.; Snowden-Ifft, D.P.; Ohnuki, T.; Spooner, N.; Lehner, M.

    2000-01-01

    The spatial resolution in drift chamber detectors for ionizing radiation is limited by diffusion of the primary electrons. A strong magnetic field along the drift direction is often applied (Fancher et al., Nucl. Instr. and Meth. A 161 (1979) 383) because it suppresses the transverse diffusion, improving the resolution but at considerable increase in cost and complexity. Here we show that transverse track diffusion can be strongly suppressed without any magnetic field. This is achieved by using a gas additive which reversibly captures primary ionization electrons, forming negative ions. The ions drift with thermal energies even at very high drift fields and low pressures (E/P=28.5 V/cm torr), and the diffusion decreases with increasing drift field. Upon arrival at the avalanche region of the chamber the negative ions are efficiently stripped and ordinary avalanche gain is obtained. Using this technique, r.m.s. transverse diffusion less than 200 μm has been achieved over a 15 cm drift path at 40 torr with zero magnetic field. The method can provide high spatial resolution in detectors with long drift distances and zero magnetic field. Negative ion drift chambers would be particularly useful at low pressures and in situations such as space-based or underground experiments where detector size scaleability is important and cost, space, or power constraints preclude the use of a magnetic field

  12. Energy drift in reversible time integration

    International Nuclear Information System (INIS)

    McLachlan, R I; Perlmutter, M

    2004-01-01

    Energy drift is commonly observed in reversible integrations of systems of molecular dynamics. We show that this drift can be modelled as a diffusion and that the typical energy error after time T is O(√T). (letter to the editor)

  13. Iceberg drift modelling in the Barents Sea

    Science.gov (United States)

    Panasenkova, Irina; Gusev, Anatoly; Fomin, Vladimir; Diansky, Nikolay; Korshenko, Evgeniya; Marchenko, Aleksey

    2017-04-01

    Iceberg drift model is developed in the N.N.Zubov State Oceanographic Institute (SOI) of the Roshydromet. The model is forced by atmospheric reanalysis data from the Weather Research and Forecasting model (WRF) and by ocean and sea ice data from the Institute of Numerical Mathematics Ocean Model (INMOM). The iceberg drift model is validated using observations of iceberg drift trajectory obtained during the annual expedition of RV Lance in the beginning of May 2009 in the Barents Sea. Field data collected in this expedition are also used for the modelling of iceberg drift. Verification tests with hindcast data from selected atmospheric and oceanic models and data from field studies were carried out to compare model predictions with field observations. Two different approaches are used to simulate iceberg drift. The first approach is a variation of wind and water drag coefficients in order to simulate the observed iceberg drift trajectory. High uncertainties in environmental driving forces and in iceberg shape and mass resulted in using ensemble forecast technique, which is the second approach to simulate the iceberg trajectory. The presented iceberg drift model shows a good capability of reproducing the observed iceberg drift.

  14. The high momentum spectrometer drift chambers

    Science.gov (United States)

    Abbott, D.; Baker, O. K.; Beaufait, J.; Bennett, C.; Bryant, E.; Carlini, R.; Kross, B.; McCauley, A.; Naing, W.; Shin, T.; Vulcan, W.

    1992-12-01

    The High Momentum Spectrometer in Hall C will use planar drift chambers for charged particle track reconstruction. The chambers are constructed using well understood technology and a conventional gas mixture. Two (plus one spare) drift chambers will be constructed for this spectrometers. Each chamber will contain 6 planes of readout channels. This paper describes the chamber design and gas handling system used.

  15. Vaccination and antigenic drift in influenza.

    Science.gov (United States)

    Boni, Maciej F

    2008-07-18

    The relationship between influenza antigenic drift and vaccination lies at the intersection of evolutionary biology and public health, and it must be viewed and analyzed in both contexts simultaneously. In this paper, 1 review what is known about the effects of antigenic drift on vaccination and the effects of vaccination on antigenic drift, and I suggest some simple ways to detect the presence of antigenic drift in seasonal influenza data. If antigenic drift occurs on the time scale of a single influenza season, it may be associated with the presence of herd immunity at the beginning of the season and may indicate a need to monitor for vaccine updates at the end of the season. The relationship between antigenic drift and vaccination must also be viewed in the context of the global circulation of influenza strains and the seeding of local and regional epidemics. In the data sets I consider--from New Zealand, New York, and France--antigenic drift can be statistically detected during some seasons, and seeding of epidemics appears to be endogenous sometimes and exogenous at other times. Improved detection of short-term antigenic drift and epidemic seeding would significantly benefit influenza monitoring efforts and vaccine selection.

  16. FIELD INVESTIGATION OF THE DRIFT SHADOW

    International Nuclear Information System (INIS)

    G.W. Su; T.J. Kneafsey

    2006-01-01

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rock mass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming the existence of the drift shadow have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow--and the corresponding hydrological process at the Hazel-Atlas silica-sand mine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rock mass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content using a gravimetric technique, as well as analyzed for chemistry. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift

  17. A stringently controlled expression system for analysing lateral gene transfer between bacteria.

    Science.gov (United States)

    Jaenecke, S; de Lorenzo, V; Timmis, K N; Díaz, E

    1996-07-01

    The lateral transfer of genetic information among microorganisms is a major force driving the outstanding adaptability of microbial communities to environmental changes. Until now little information has been obtained on gene transfer in natural ecosystems. We present here a genetic circuit for detecting and quantifying horizontal gene transfer from a defined donor microorganism to recipient organisms in the absence of selection for a recipient-specific phenotype. The system consists of an engineered lacZ (encoding beta-galactosidase) reporter gene whose expression is controlled by a synthetic regulatory element based on a fusion between the Pr promoter-operator from lambda bacteriophage and the 5' non-coding leader region of the inp gene encoding the IS 10 transposase function. Expression of this reporter cassette in the recombinant microorganism is completely shut down by two chromosomally encoded trans-acting repressors working at the level of transcription (the Cl-EK117 protein from the lambda phage), and at the level of translation (the antisense RNA-OUT of the IS 10 element). When the reporter element is transferred to a different host by any mechanism, it escapes repression and becomes expressed. The system was validated with Pseudo-monas putida, and conjugational transfer frequencies of the reporter element as low as 10(-6) were detected. The modular design and broad host range of the genetic circuit, in combination with biomarkers which permit real-time in situ detection, will facilitate the monitor-ing of gene flow in a non-disruptive manner within the environment.

  18. Dissipative drift instability in dusty plasma

    Directory of Open Access Journals (Sweden)

    Nilakshi Das

    2012-03-01

    Full Text Available An investigation has been done on the very low-frequency electrostatic drift waves in a collisional dusty plasma. The dust density gradient is taken perpendicular to the magnetic field B0⃗, which causes the drift wave. In this case, low-frequency drift instabilities can be driven by E1⃗×B0⃗ and diamagnetic drifts, where E1⃗ is the perturbed electric field. Dust charge fluctuation is also taken into consideration for our study. The dust- neutral and ion-neutral collision terms have been included in equations of motion. It is seen that the low-frequency drift instability gets damped in such a system. Both dust charging and collision of plasma particles with the neutrals may be responsible for the damping of the wave. Both analytical and numerical techniques have been used while developing the theory.

  19. Role of drifts in diffusive shock acceleration

    International Nuclear Information System (INIS)

    Decker, R.B.

    1988-01-01

    The role played by shock-associated drifts during the diffusive acceleration of charged particles at collisionless MHD shocks is evaluated. In the rest frame of the shock, the total energy gained by a particle is shown to result from two coupled acceleration mechanisms, the usual first-order Fermi mechanism and the drift mechanism. When averaged over a distribution of particles, the ratio of the drift-associated energy gain to the total energy is found to be independent of the total energy at a given theta1 (the angle between the shock normal and the unperturbed upstream magnetic field) in agreement with theoretical predictions. No evidence is found for drift-associated deceleration, suggesting that drifts always augment acceleration. 35 references

  20. Drift velocity and pressure monitoring of the CMS muon drift chambers

    CERN Document Server

    Sonnenschein, Lars

    2011-01-01

    The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented. Another important parameter to be monitored is the pressure inside the muon drift tube chambers. The differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest drift velocity monitoring results are discussed.

  1. Drift velocity and pressure monitoring of the CMS muon drift chambers

    CERN Document Server

    Sonnenschein, Lars

    2010-01-01

    The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented. Another important parameter to be monitored is the pressure inside the muon drift tube chambers because the drift velocity depends on it. Furthermore the differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest pressure monitoring results are discussed.

  2. Field investigation of the drift shadow

    International Nuclear Information System (INIS)

    Su, Grace W.; Kneafsey, Timothy J.; Ghezzehei, Teamrat A.; Marshall, Brian D.; Cook, Paul J.

    2005-01-01

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rockmass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming its existence have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow and the corresponding hydrological process at the Hazel-Atlas silica-sandmine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine Formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rockmass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content and chemical constituents. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift. Tensiometers, electrical resistance probes, neutron probes, and ground

  3. Synthetic Peptides to Target Stringent Response-Controlled Virulence in a Pseudomonas aeruginosa Murine Cutaneous Infection Model

    Directory of Open Access Journals (Sweden)

    Daniel Pletzer

    2017-09-01

    Full Text Available Microorganisms continuously monitor their surroundings and adaptively respond to environmental cues. One way to cope with various stress-related situations is through the activation of the stringent stress response pathway. In Pseudomonas aeruginosa this pathway is controlled and coordinated by the activity of the RelA and SpoT enzymes that metabolize the small nucleotide secondary messenger molecule (pppGpp. Intracellular ppGpp concentrations are crucial in mediating adaptive responses and virulence. Targeting this cellular stress response has recently been the focus of an alternative approach to fight antibiotic resistant bacteria. Here, we examined the role of the stringent response in the virulence of P. aeruginosa PAO1 and the Liverpool epidemic strain LESB58. A ΔrelA/ΔspoT double mutant showed decreased cytotoxicity toward human epithelial cells, exhibited reduced hemolytic activity, and caused down-regulation of the expression of the alkaline protease aprA gene in stringent response mutants grown on blood agar plates. Promoter fusions of relA or spoT to a bioluminescence reporter gene revealed that both genes were expressed during the formation of cutaneous abscesses in mice. Intriguingly, virulence was attenuated in vivo by the ΔrelA/ΔspoT double mutant, but not the relA mutant nor the ΔrelA/ΔspoT complemented with either gene. Treatment of a cutaneous P. aeruginosa PAO1 infection with anti-biofilm peptides increased animal welfare, decreased dermonecrotic lesion sizes, and reduced bacterial numbers recovered from abscesses, resembling the phenotype of the ΔrelA/ΔspoT infection. It was previously demonstrated by our lab that ppGpp could be targeted by synthetic peptides; here we demonstrated that spoT promoter activity was suppressed during cutaneous abscess formation by treatment with peptides DJK-5 and 1018, and that a peptide-treated relA complemented stringent response double mutant strain exhibited reduced peptide

  4. The relative role of drift and selection in shaping the human skull.

    Science.gov (United States)

    Betti, Lia; Balloux, François; Hanihara, Tsunehiko; Manica, Andrea

    2010-01-01

    Human populations across the world vary greatly in cranial morphology. It is highly debated to what extent this variability has accumulated through neutral processes (genetic drift) or through natural selection driven by climate. By taking advantage of recent work showing that geographic distance along landmasses is an excellent proxy for neutral genetic differentiation, we quantify the relative role of drift versus selection in an exceptionally large dataset of human skulls. We show that neutral processes have been much more important than climate in shaping the human cranium. We further demonstrate that a large proportion of the signal for natural selection comes from populations from extremely cold regions. More generally, we show that, if drift is not explicitly accounted for, the effect of natural selection can be greatly overestimated.

  5. Low genetic diversity and high genetic differentiation among ...

    African Journals Online (AJOL)

    Possible reasons for the high population genetic differentiation and the low levels of genetic variation within populations are inbreeding and genetic drift. Of a total of 26 known populations, 14 are now extinct, five during the course of this study. Action to prevent complete extinction of the species is therefore urgent.

  6. Drift-modeling and monitoring comparisons

    International Nuclear Information System (INIS)

    Chen, N.C.J.; Hanna, S.R.

    1977-01-01

    Congress is looking into the conglomeration of nuclear reactors into energy centers of limited area. Drift from cooling towers can corrode and damage structures in the immediate vicinity of the towers, cause a public nuisance if located near parking lots or high-density traffic areas, and endanger local vegetation. The estimation of salt deposition has relied primarily on predictions from a variety of models, with very few direct measurements. One of the major efforts in our program is to evaluate the assumptions, limitations, and applicabilities of various analytical models for drift deposition prediction. Several drift deposition models are compared using a set of standard input conditions. The predicted maximum drift deposition differs by two orders of magnitude, and the downwind locations of the maximum differ by one order of magnitude. The discrepancies are attributed mainly to different assumptions in the models regarding the initial effective height of the droplets. Current programs in which drift characteristics at the tower mouth and drift deposition downwind of the tower are being measured are summarized. At the present time, drift deposition measurements, sufficiently comprehensive for model verifications, are unavailable. Hopefully, the Chalk Point Program will satisfy this need

  7. Numerical analysis of nonlinear collisional drift instability

    Energy Technology Data Exchange (ETDEWEB)

    Nishi-kawa, K.I.; Hatori, T.; Terashima, Y.

    1978-04-01

    The nonlinear evolution of collisional drift wave instability is studied numerically. Model equations of quasilinear type are used which describe the modification of background density and the amplitude of unstable drift wave. Their solutions are classified according to the value of a parameter (n) which is proportional to the ratio of ion viscous damping to linear growth rate. In the vicinity of marginal stability, the unstable drift waves are shown to be saturated by flattening of the background density. An N decreases further, periodic and later aperiodic solutions are obtained. The wave associated diffusion coefficient is obtained numerically as a function of N and found to be much less than the usual estimate.

  8. Nonlinear Gyrokinetic Theory With Polarization Drift

    International Nuclear Information System (INIS)

    Wang, L.; Hahm, T.S.

    2010-01-01

    A set of the electrostatic toroidal gyrokinetic Vlasov equation and the Poisson equation, which explicitly includes the polarization drift, is derived systematically by using Lie-transform method. The polarization drift is introduced in the gyrocenter equations of motion, and the corresponding polarization density is derived. Contrary to the wide-spread expectation, the inclusion of the polarization drift in the gyrocenter equations of motion does not affect the expression for the polarization density significantly. This is due to modification of the gyrocenter phase-space volume caused by the electrostatic potential [T. S. Hahm, Phys. Plasmas 3, 4658 (1996)].

  9. Heuristic Drift Elimination for Personnel Tracking Systems

    Science.gov (United States)

    Borenstein, Johann; Ojeda, Lauro

    This paper pertains to the reduction of the effects of measurement errors in rate gyros used for tracking, recording, or monitoring the position of persons walking indoors. In such applications, bias drift and other gyro errors can degrade accuracy within minutes. To overcome this problem we developed the Heuristic Drift Elimination (HDE) method, that effectively corrects bias drift and other slow-changing errors. HDE works by making assumptions about walking in structured, indoor environments. The paper explains the heuristic assumptions and the HDE method, and shows experimental results. In typical applications, HDE maintains near-zero heading errors in walks of unlimited duration.

  10. Pixelated CdZnTe drift detectors

    DEFF Research Database (Denmark)

    Kuvvetli, Irfan; Budtz-Jørgensen, Carl

    2005-01-01

    A technique, the so-called Drift Strip Method (DSM), for improving the CdZnTe detector energy response to hard X-rays and gamma-rays was applied as a pixel geometry. First tests have confirmed that this detector type provides excellent energy resolution and imaging performance. We specifically...... report on the performance of 3 mm thick prototype CZT drift pixel detectors fabricated using material from eV-products. We discuss issues associated with detector module performance. Characterization results obtained from several prototype drift pixel detectors are presented. Results of position...

  11. Drift of continental rafts with asymmetric heating.

    Science.gov (United States)

    Knopoff, L; Poehls, K A; Smith, R C

    1972-06-02

    A laboratory model of a lithospheric raft is propelled through a viscous asthenospheric layer with constant velocity of scaled magnitude appropriate to continental drift. The propulsion is due to differential heat concentration in the model oceanic and continental crusts.

  12. Drift and Behavior of E. coli Cells

    Science.gov (United States)

    Micali, Gabriele; Colin, Rémy; Sourjik, Victor; Endres, Robert G.

    2017-12-01

    Chemotaxis of the bacterium Escherichia coli is well understood in shallow chemical gradients, but its swimming behavior remains difficult to interpret in steep gradients. By focusing on single-cell trajectories from simulations, we investigated the dependence of the chemotactic drift velocity on attractant concentration in an exponential gradient. While maxima of the average drift velocity can be interpreted within analytical linear-response theory of chemotaxis in shallow gradients, limits in drift due to steep gradients and finite number of receptor-methylation sites for adaptation go beyond perturbation theory. For instance, we found a surprising pinning of the cells to the concentration in the gradient at which cells run out of methylation sites. To validate the positions of maximal drift, we recorded single-cell trajectories in carefully designed chemical gradients using microfluidics.

  13. CROSS DRIFT ALCOVE/NICHE UTILITIES ANALYSIS

    International Nuclear Information System (INIS)

    S. Goodin

    1999-01-01

    The purpose of this analysis is to provide the design basis and general arrangement requirements of the non-potable water, waste water, compressed air and ventilation (post excavation) utilities required in support of the Cross Drift alcoves and niches

  14. Stabilization Strategies for Drift Tube Linacs

    CERN Document Server

    AUTHOR|(CDS)2085420; Lamehi Rashti, Mohammad

    The average axial electric fields in drift tube linac cavities are known to be sensitive with respect to the perturbation errors. Postcoupler is a powerful stabilizer devices that is used to reduce this sensitivity of average axial field. Postcouplers are the cylindrical rod which is extended from cavity wall toward the drift tube without touching the drift tube surface. Postcouplers need to be adjusted to the right length to stabilize the average axial field. Although postcouplers are used successfully in many projects, there is no straightforward procedure for postcouplers adjustment and it has been done almost based on trial and errors. In this thesis, the physics and characteristics of postcouplers has been studied by using an equivalent circuit model and 3D finite element method calculations. Finally, a straightforward and accurate method to adjust postcouplers has been concluded. The method has been verified by using experimental measurements on CERN Linac4 drift tube linac cavities.

  15. SEEPAGE MODEL FOR PA INCLUDING DRIFT COLLAPSE

    International Nuclear Information System (INIS)

    C. Tsang

    2004-01-01

    The purpose of this report is to document the predictions and analyses performed using the seepage model for performance assessment (SMPA) for both the Topopah Spring middle nonlithophysal (Tptpmn) and lower lithophysal (Tptpll) lithostratigraphic units at Yucca Mountain, Nevada. Look-up tables of seepage flow rates into a drift (and their uncertainty) are generated by performing numerical simulations with the seepage model for many combinations of the three most important seepage-relevant parameters: the fracture permeability, the capillary-strength parameter 1/a, and the percolation flux. The percolation flux values chosen take into account flow focusing effects, which are evaluated based on a flow-focusing model. Moreover, multiple realizations of the underlying stochastic permeability field are conducted. Selected sensitivity studies are performed, including the effects of an alternative drift geometry representing a partially collapsed drift from an independent drift-degradation analysis (BSC 2004 [DIRS 166107]). The intended purpose of the seepage model is to provide results of drift-scale seepage rates under a series of parameters and scenarios in support of the Total System Performance Assessment for License Application (TSPA-LA). The SMPA is intended for the evaluation of drift-scale seepage rates under the full range of parameter values for three parameters found to be key (fracture permeability, the van Genuchten 1/a parameter, and percolation flux) and drift degradation shape scenarios in support of the TSPA-LA during the period of compliance for postclosure performance [Technical Work Plan for: Performance Assessment Unsaturated Zone (BSC 2002 [DIRS 160819], Section I-4-2-1)]. The flow-focusing model in the Topopah Spring welded (TSw) unit is intended to provide an estimate of flow focusing factors (FFFs) that (1) bridge the gap between the mountain-scale and drift-scale models, and (2) account for variability in local percolation flux due to

  16. Neutron recoils in the DRIFT detector

    International Nuclear Information System (INIS)

    Snowden-Ifft, D.P.; Ohnuki, T.; Rykoff, E.S.; Martoff, C.J.

    2003-01-01

    The Directional Recoil Identification From Tracks (DRIFT) project is an endeavor to build and operate a low pressure negative ion TPC to search for weakly interacting massive particles thought to make up the dark matter in our Galaxy. This paper will focus on a neutron exposure of a small DRIFT prototype, a Monte Carlo to simulate these events, and the derivation of the range and ionization as a function of energy for Sulfur and Carbon recoils in CS 2 gas

  17. Drift waves in a weakly ionized plasma

    DEFF Research Database (Denmark)

    Popovic, M.; Melchior, H.

    1968-01-01

    A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated.......A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated....

  18. Strange Attractors in Drift Wave Turbulence

    International Nuclear Information System (INIS)

    Lewandowski, J.L.V.

    2003-01-01

    A multi-grid part-in-cell algorithm for a shearless slab drift wave model with kinetic electrons is presented. The algorithm, which is based on an exact separation of adiabatic and nonadiabatic electron responses, is used to investigate the presence of strange attractors in drift wave turbulence. Although the simulation model has a large number of degrees of freedom, it is found that the strange attractor is low-dimensional and that it is strongly affected by dissipative (collisional) effects

  19. Status of the KEDR drift chamber

    CERN Document Server

    Baru, S E; Blinov, V E; Groshev, V R; Kolachev, G M; Minakov, G D; Onuchin, A P; Popkov, I N; Savinov, G A; Shamov, A G; Shusharo, A I; Talyshev, A A; Todyshev, K Y; Yushkov, A N

    2002-01-01

    The 1 m long and 1 m outer diameter chamber consists of 42 layers. The chamber is based on a jet type cells with drift distance of 30 mm. The measurements of the spatial and dE/dx resolution were performed with DME gas with the cosmic particles. The resolution averaged over the drift distance is equal to 110 mu m while dE/dx resolution is 8.2%.

  20. Effects of Fault Displacement on Emplacement Drifts

    International Nuclear Information System (INIS)

    Duan, F.

    2000-01-01

    The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10 -5 adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M and O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure

  1. Beam test results of a drift velocity monitoring system for silicon drift detectors

    CERN Document Server

    Nouais, D; Bonvicini, V; Cerello, P; Giubellino, P; Hernández-Montoya, R; Kolojvari, A; Mazza, G; Nissinen, J; Rashevsky, A; Rivetti, A; Tosello, F; Vacchi, A

    2002-01-01

    We report results on drift velocity monitoring using MOS charge injectors in silicon drift detectors obtained in beam test conditions. The correction of velocity variations as small as 0.03% caused by temperature variations of the order of 0.04 K allowed to get an average space resolution along all the drift path of 28 mu m. Preliminary result demonstrating the possibility to correct for temperature gradients along the anode axis are also presented.

  2. Suppressing drift chamber diffusion without magnetic field

    CERN Document Server

    Martoff, C J; Ohnuki, T; Spooner, N J C; Lehner, M

    2000-01-01

    The spatial resolution in drift chamber detectors for ionizing radiation is limited by diffusion of the primary electrons. A strong magnetic field along the drift direction is often applied (Fancher et al., Nucl. Instr. and Meth. A 161 (1979) 383) because it suppresses the transverse diffusion, improving the resolution but at considerable increase in cost and complexity. Here we show that transverse track diffusion can be strongly suppressed without any magnetic field. This is achieved by using a gas additive which reversibly captures primary ionization electrons, forming negative ions. The ions drift with thermal energies even at very high drift fields and low pressures (E/P=28.5 V/cm torr), and the diffusion decreases with increasing drift field. Upon arrival at the avalanche region of the chamber the negative ions are efficiently stripped and ordinary avalanche gain is obtained. Using this technique, r.m.s. transverse diffusion less than 200 mu m has been achieved over a 15 cm drift path at 40 torr with ze...

  3. Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dimitrov, A; Dyulendarova, M; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Toteva, Z; Chen, G M; Chen, H S; Guan, W; Jiang, C H; Liang, D; Liu, B; Meng, X; Tao, J; Wang, J; Wang, Z; Xue, Z; Zhang, Z; Ban, Y; Cai, J; Ge, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Avila, C; Baquero Ruiz, M; Carrillo Montoya, C A; Gomez, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Reyes Romero, D; Sanabria, J C; Godinovic, N; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Fereos, R; Galanti, M; Mousa, J; Papadakis, A; Ptochos, F; Razis, P A; Tsiakkouri, D; Zinonos, Z; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Anttila, E; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Nysten, J; Tuominen, E; Tuominiemi, J; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Nedelec, P; Sillou, D; Besancon, M; Chipaux, R; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Lemaire, M C; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Busson, P; Charlot, C; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Paganini, P; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J L; Besson, A; Bloch, D; Bodin, D; Brom, J M; Conte, E; Drouhin, F; Fontaine, J C; Gelé, D; Goerlach, U; Gross, L; Juillot, P; Le Bihan, A C; Patois, Y; Speck, J; Van Hove, P; Baty, C; Bedjidian, M; Blaha, J; Boudoul, G; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; Dupasquier, T; El Mamouni, H; Fassi, F; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Lumb, N; Mirabito, L; Perries, S; Vander Donckt, M; Verdier, P; Djaoshvili, N; Roinishvili, N; Roinishvili, V; Amaglobeli, N; Adolphi, R; Anagnostou, G; Brauer, R; Braunschweig, W; Edelhoff, M; Esser, H; Feld, L; Karpinski, W; Khomich, A; Klein, K; Mohr, N; Ostaptchouk, A; Pandoulas, D; Pierschel, G; Raupach, F; Schael, S; Schultz von Dratzig, A; Schwering, G; Sprenger, D; Thomas, M; Weber, M; Wittmer, B; Wlochal, M; Actis, O; Altenhöfer, G; Bender, W; Biallass, P; Erdmann, M; Fetchenhauer, G; Frangenheim, J; Hebbeker, T; Hilgers, G; Hinzmann, A; Hoepfner, K; Hof, C; Kirsch, M; Klimkovich, T; Kreuzer, P; Lanske, D; Merschmeyer, M; Meyer, A; Philipps, B; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Sowa, M; Steggemann, J; Szczesny, H; Teyssier, D; Zeidler, C; Bontenackels, M; Davids, M; Duda, M; Flügge, G; Geenen, H; Giffels, M; Haj Ahmad, W; Hermanns, T; Heydhausen, D; Kalinin, S; Kress, T; Linn, A; Nowack, A; Perchalla, L; Poettgens, M; Pooth, O; Sauerland, P; Stahl, A; Tornier, D; Zoeller, M H; Aldaya Martin, M; Behrens, U; Borras, K; Campbell, A; Castro, E; Dammann, D; Eckerlin, G; Flossdorf, A; Flucke, G; Geiser, A; Hatton, D; Hauk, J; Jung, H; Kasemann, M; Katkov, I; Kleinwort, C; Kluge, H; Knutsson, A; Kuznetsova, E; Lange, W; Lohmann, W; Mankel, R; Marienfeld, M; Meyer, A B; Miglioranzi, S; Mnich, J; Ohlerich, M; Olzem, J; Parenti, A; Rosemann, C; Schmidt, R; Schoerner-Sadenius, T; Volyanskyy, D; Wissing, C; Zeuner, W D; Autermann, C; Bechtel, F; Draeger, J; Eckstein, D; Gebbert, U; Kaschube, K; Kaussen, G; Klanner, R; Mura, B; Naumann-Emme, S; Nowak, F; Pein, U; Sander, C; Schleper, P; Schum, T; Stadie, H; Steinbrück, G; Thomsen, J; Wolf, R; Bauer, J; Blüm, P; Buege, V; Cakir, A; Chwalek, T; De Boer, W; Dierlamm, A; Dirkes, G; Feindt, M; Felzmann, U; Frey, M; Furgeri, A; Gruschke, J; Hackstein, C; Hartmann, F; Heier, S; Heinrich, M; Held, H; Hirschbuehl, D; Hoffmann, K H; Honc, S; Jung, C; Kuhr, T; Liamsuwan, T; Martschei, D; Mueller, S; Müller, Th; Neuland, M B; Niegel, M; Oberst, O; Oehler, A; Ott, J; Peiffer, T; Piparo, D; Quast, G; Rabbertz, K; Ratnikov, F; Ratnikova, N; Renz, M; Saout, C; Sartisohn, G; Scheurer, A; Schieferdecker, P; Schilling, F P; Schott, G; Simonis, H J; Stober, F M; Sturm, P; Troendle, D; Trunov, A; Wagner, W; Wagner-Kuhr, J; Zeise, M; Zhukov, V; Ziebarth, E B; Daskalakis, G; Geralis, T; Karafasoulis, K; Kyriakis, A; Loukas, D; Markou, A; Markou, C; Mavrommatis, C; Petrakou, E; Zachariadou, A; Gouskos, L; Katsas, P; Panagiotou, A; Evangelou, I; Kokkas, P; Manthos, N; Papadopoulos, I; Patras, V; Triantis, F A; Bencze, G; Boldizsar, L; Debreczeni, G; Hajdu, C; Hernath, S; Hidas, P; Horvath, D; Krajczar, K; Laszlo, A; Patay, G; Sikler, F; Toth, N; Vesztergombi, G; Beni, N; Christian, G; Imrek, J; Molnar, J; Novak, D; Palinkas, J; Szekely, G; Szillasi, Z; Tokesi, K; Veszpremi, V; Kapusi, A; Marian, G; Raics, P; Szabo, Z; Trocsanyi, Z L; Ujvari, B; Zilizi, G; Bansal, S; Bawa, H S; Beri, S B; Bhatnagar, V; Jindal, M; Kaur, M; Kaur, R; Kohli, J M; Mehta, M Z; Nishu, N; Saini, L K; Sharma, A; Singh, A; Singh, J B; Singh, S P; Ahuja, S; Arora, S; Bhattacharya, S; Chauhan, S; Choudhary, B C; Gupta, P; Jain, S; Jha, M; Kumar, A; Ranjan, K; Shivpuri, R K; Srivastava, A K; Choudhury, R K; Dutta, D; Kailas, S; Kataria, S K; Mohanty, A K; Pant, L M; Shukla, P; Topkar, A; Aziz, T; Guchait, M; Gurtu, A; Maity, M; Majumder, D; Majumder, G; Mazumdar, K; Nayak, A; Saha, A; Sudhakar, K; Banerjee, S; Dugad, S; Mondal, N K; Arfaei, H; Bakhshiansohi, H; Fahim, A; Jafari, A; Mohammadi Najafabadi, M; Moshaii, A; Paktinat Mehdiabadi, S; Rouhani, S; Safarzadeh, B; Zeinali, M; Felcini, M; Abbrescia, M; Barbone, L; Chiumarulo, F; Clemente, A; Colaleo, A; Creanza, D; Cuscela, G; De Filippis, N; De Palma, M; De Robertis, G; Donvito, G; Fedele, F; Fiore, L; Franco, M; Iaselli, G; Lacalamita, N; Loddo, F; Lusito, L; Maggi, G; Maggi, M; Manna, N; Marangelli, B; My, S; Natali, S; Nuzzo, S; Papagni, G; Piccolomo, S; Pierro, G A; Pinto, C; Pompili, A; Pugliese, G; Rajan, R; Ranieri, A; Romano, F; Roselli, G; Selvaggi, G; Shinde, Y; Silvestris, L; Tupputi, S; Zito, G; Abbiendi, G; Bacchi, W; Benvenuti, A C; Boldini, M; Bonacorsi, D; Braibant-Giacomelli, S; Cafaro, V D; Caiazza, S S; Capiluppi, P; Castro, A; Cavallo, F R; Codispoti, G; Cuffiani, M; D'Antone, I; Dallavalle, G M; Fabbri, F; Fanfani, A; Fasanella, D; Giacomelli, P; Giordano, V; Giunta, M; Grandi, C; Guerzoni, M; Marcellini, S; Masetti, G; Montanari, A; Navarria, F L; Odorici, F; Pellegrini, G; Perrotta, A; Rossi, A M; Rovelli, T; Siroli, G; Torromeo, G; Travaglini, R; Albergo, S; Costa, S; Potenza, R; Tricomi, A; Tuve, C; Barbagli, G; Broccolo, G; Ciulli, V; Civinini, C; D'Alessandro, R; Focardi, E; Frosali, S; Gallo, E; Genta, C; Landi, G; Lenzi, P; Meschini, M; Paoletti, S; Sguazzoni, G; Tropiano, A; Benussi, L; Bertani, M; Bianco, S; Colafranceschi, S; Colonna, D; Fabbri, F; Giardoni, M; Passamonti, L; Piccolo, D; Pierluigi, D; Ponzio, B; Russo, A; Fabbricatore, P; Musenich, R; Benaglia, A; Calloni, M; Cerati, G B; D'Angelo, P; De Guio, F; Farina, F M; Ghezzi, A; Govoni, P; Malberti, M; Malvezzi, S; Martelli, A; Menasce, D; Miccio, V; Moroni, L; Negri, P; Paganoni, M; Pedrini, D; Pullia, A; Ragazzi, S; Redaelli, N; Sala, S; Salerno, R; Tabarelli de Fatis, T; Tancini, V; Taroni, S; Buontempo, S; Cavallo, N; Cimmino, A; De Gruttola, M; Fabozzi, F; Iorio, A O M; Lista, L; Lomidze, D; Noli, P; Paolucci, P; Sciacca, C; Azzi, P; Bacchetta, N; Barcellan, L; Bellan, P; Bellato, M; Benettoni, M; Biasotto, M; Bisello, D; Borsato, E; Branca, A; Carlin, R; Castellani, L; Checchia, P; Conti, E; Dal Corso, F; De Mattia, M; Dorigo, T; Dosselli, U; Fanzago, F; Gasparini, F; Gasparini, U; Giubilato, P; Gonella, F; Gresele, A; Gulmini, M; Kaminskiy, A; Lacaprara, S; Lazzizzera, I; Margoni, M; Maron, G; Mattiazzo, S; Mazzucato, M; Meneghelli, M; Meneguzzo, A T; Michelotto, M; Montecassiano, F; Nespolo, M; Passaseo, M; Pegoraro, M; Perrozzi, L; Pozzobon, N; Ronchese, P; Simonetto, F; Toniolo, N; Torassa, E; Tosi, M; Triossi, A; Vanini, S; Ventura, S; Zotto, P; Zumerle, G; Baesso, P; Berzano, U; Bricola, S; Necchi, M M; Pagano, D; Ratti, S P; Riccardi, C; Torre, P; Vicini, A; Vitulo, P; Viviani, C; Aisa, D; Aisa, S; Babucci, E; Biasini, M; Bilei, G M; Caponeri, B; Checcucci, B; Dinu, N; Fanò, L; Farnesini, L; Lariccia, P; Lucaroni, A; Mantovani, G; Nappi, A; Piluso, A; Postolache, V; Santocchia, A; Servoli, L; Tonoiu, D; Vedaee, A; Volpe, R; Azzurri, P; Bagliesi, G; Bernardini, J; Berretta, L; Boccali, T; Bocci, A; Borrello, L; Bosi, F; Calzolari, F; Castaldi, R; Dell'Orso, R; Fiori, F; Foà, L; Gennai, S; Giassi, A; Kraan, A; Ligabue, F; Lomtadze, T; Mariani, F; Martini, L; Massa, M; Messineo, A; Moggi, A; Palla, F; Palmonari, F; Petragnani, G; Petrucciani, G; Raffaelli, F; Sarkar, S; Segneri, G; Serban, A T; Spagnolo, P; Tenchini, R; Tolaini, S; Tonelli, G; Venturi, A; Verdini, P G; Baccaro, S; Barone, L; Bartoloni, A; Cavallari, F; Dafinei, I; Del Re, D; 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D'Enterria, D; Everaerts, P; Gomez Ceballos, G; Hahn, K A; Harris, P; Jaditz, S; Kim, Y; Klute, M; Lee, Y J; Li, W; Loizides, C; Ma, T; Miller, M; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G; Sumorok, K; Sung, K; Vaurynovich, S; Wenger, E A; Wyslouch, B; Xie, S; Yilmaz, Y; Yoon, A S; Bailleux, D; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dolgopolov, A; Dudero, P R; Egeland, R; Franzoni, G; Haupt, J; Inyakin, A; Klapoetke, K; Kubota, Y; Mans, J; Mirman, N; Petyt, D; Rekovic, V; Rusack, R; Schroeder, M; Singovsky, A; Zhang, J; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Sonnek, P; Summers, D; Bloom, K; Bockelman, B; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Strang, M; Alverson, G; Barberis, E; Boeriu, O; Eulisse, G; Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; Swain, J; Taylor, L; Tuura, L; Anastassov, A; Gobbi, B; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Warchol, J; Wayne, M; Bylsma, B; Durkin, L S; Gilmore, J; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Garmash, A; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Wildish, T; Xie, Z; Zuranski, A; Acosta, J G; Bonnett Del Alamo, M; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Santacruz, N; Zatzerklyany, A; Alagoz, E; Antillon, E; Barnes, V E; Bolla, G; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Ippolito, N; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Sedov, A; Shipsey, I; Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    This paper describes the calibration procedure for the drift tubes of the CMS barrel muon system and reports the main results obtained with data collected during a high statistics cosmic ray data-taking period. The main goal of the calibration is to determine, for each drift cell, the minimum time delay for signals relative to the trigger, accounting for the drift velocity within the cell. The accuracy of the calibration procedure is influenced by the random arrival time of cosmic muons. A more refined analysis of the drift velocity was performed during the offline reconstruction phase, which takes into account this feature of cosmic ray events.

  4. Concentrated Hitting Times of Randomized Search Heuristics with Variable Drift

    DEFF Research Database (Denmark)

    Lehre, Per Kristian; Witt, Carsten

    2014-01-01

    these results handle a position-dependent (variable) drift that was not covered by previous drift theorems with tail bounds. Moreover, our theorem can be specialized into virtually all existing drift theorems with drift towards the target from the literature. Finally, user-friendly specializations...

  5. Genetic variation and population structure in Oryza ...

    Indian Academy of Sciences (India)

    Genetically isolated smaller populations and a narrow genetic base in O. malampuzhaensis point to its vulnerability to genetic drift and genetic depauperation. Thus O. malampuzhaensis appears to be under the threat of extinction and needs to be conserved by use of suitable methods. The present study also identified ...

  6. Rater Severity Drift in Peer Assessment

    Directory of Open Access Journals (Sweden)

    Bengü BÖRKAN

    2017-12-01

    Full Text Available There are not enough psychometrically sound studies about the validity and reliability of the scores obtained from peer assessment. This study examined degree of rater severity drift, a rater effect, in peer assessment. The college students’ presentations were scored by 29 peers in the class using a rating scale. Nine presentations were held on four separate days, two presentations on each of the first three days and three presentations on the fourth day. Drift was investigated with two many-facet Rasch measurement models (separate models and dummy time MFRM. Standardized differences were calculated from the estimates obtained with separate models and interaction terms were calculated with the dummy time MFRM. In drift analysis, shifts in estimations were examined from Day-1 which is a baseline to other three days. Results showed that peer raters varied according to their level of severity and they tend to be lenient. Statistics showed that the quality of the scale was acceptable and its items behaved as expected. In drift analysis, standardized differences and interaction term provided very similar results. Between Day-1 and 2, there was no statistically significant difference in the estimates of the rater severity. Between Day-1 and 3, the percentage of scorers with significant drift in the estimates was 38.10%. The raters’ severity shifts on the average of about 0.14 logit and they displayed more severe scoring behavior. Between Day-1 and 4, the number of raters who had significant shifts in their estimates was three according to the standardized difference method, while one according to interaction method. On the average, the raters became more severe. Among three comparison, Day-4 had the largest rater severity drift on the average; Day 3, however, has the highest number of raters with rater severity drift.

  7. Optical drift effects in general relativity

    Science.gov (United States)

    Korzyński, Mikołaj; Kopiński, Jarosław

    2018-03-01

    We consider the question of determining the optical drift effects in general relativity, i.e. the rate of change of the apparent position, redshift, Jacobi matrix, angular distance and luminosity distance of a distant object as registered by an observer in an arbitrary spacetime. We present a fully relativistic and covariant approach, in which the problem is reduced to a hierarchy of ODE's solved along the line of sight. The 4-velocities and 4-accelerations of the observer and the emitter and the geometry of the spacetime along the line of sight constitute the input data. We build on the standard relativistic geometric optics formalism and extend it to include the time derivatives of the observables. In the process we obtain two general, non-perturbative relations: the first one between the gravitational lensing, represented by the Jacobi matrix, and the apparent position drift, also called the cosmic parallax, and the second one between the apparent position drift and the redshift drift. The applications of the results include the theoretical study of the drift effects of cosmological origin (so-called real-time cosmology) in numerical or exact Universe models.

  8. Drift emplaced waste package thermal response

    International Nuclear Information System (INIS)

    Ruffner, D.J.; Johnson, G.L.; Platt, E.A.; Blink, J.A.; Doering, T.W.

    1993-01-01

    Thermal calculations of the effects of radioactive waste decay heat on the I repository at Yucca Mountain, Nevada have been conducted by the Yucca Mountain Site Characterization Project (YMP) at Lawrence Livermore National Laboratory (LLNL) in conjunction with the B ampersand W Fuel Company. For a number of waste package spacings, these 3D transient calculations use the TOPAZ3D code to predict drift wall temperatures to 10,000 years following emplacement. Systematic tcniperature variation occurs as a function of fuel age at emplacement and Areal Mass Loading (AML) during the first few centuries after emplacement. After about 1000 years, emplacement age is not a strong driver on rock temperature; AML has a larger impact. High AMLs occur when large waste packages are emplaced end-tocnd in drifts. Drift emplacement of equivalent packages results in lower rock teniperatures than borehole emplacement. For an emplacement scheme with 50% of the drift length occupied by packages, an AML of 138 MTU/acre is about three times higher than the Site Characterization Plan-Conceptual Design (SCP-CD) value. With this higher AML (requiring only 1/3 of the SCP-CD repository footprint), peak drift wall temperatures do not exceed 160*C, but rock temperatures excetd the boiling point of water for about 3000 years. These TOPAZ3D results Iiive been compared with reasonable agreement with two other computer codes

  9. Electron drift velocities in fast Argon and CF4 based drift gases

    CERN Document Server

    van Apeldoorn, G

    1998-01-01

    98-063 Electron drift velocities in gas mixtures were measured in a tabletop experiment using a nitrogen laser to create the primary electrons. The maximum drift times for electrons in a 5 mm (10 mm) honeycomb drift cell at 2200 V anode voltage were 28 ns (53 ns) and 21 ns (61 ns) for Ar-Cf4-CH4 (75/18/6) and Ar-CF4-CO2 (68/27/5), respectively. Changing the ratio of the latter mix did not change the drift velocity very much. The gains of the gases are ~10^4 for a single primary electron. CF4 causes electron attachment. The measured drift times agree well with GARFIELD simulations.

  10. Community Air Monitoring for Pesticide Drift Using Pesticide Action Network's (PAN) Drift Catcher

    Science.gov (United States)

    Marquez, E.

    2016-12-01

    Community air monitoring projects for pesticides in the air have been conducted by PAN in collaboration with community members and locally based groups engaged around pesticide issues. PAN is part of an international network working to promote a just, thriving food system and replace the use of hazardous pesticides with ecologically sound alternatives. The Drift Catcher is an air-monitoring device with a design based on the California Air Resource Board's air monitoring equipment, and has been used in community-based projects in 11 states. Observations of pesticide drift made by community members cannot always be confirmed by regulatory agencies—if an inspection is made hours or days after a drift incident, the evidence may no longer be present. The Drift Catcher makes it possible to collect scientific evidence of pesticide drift in areas where people live, work, and play. One of the most recent Drift Catcher projects was done in California, in partnership with the Safe Strawberry Coalition and led by the statewide coalition Californians for Pesticide Reform. The data were used to support a call for stronger mitigation rules for the fumigant chloropicrin and to support a campaign asking for stronger pesticide rules to protect children attending school in close proximity to agricultural fields. The Drift Catcher data are used by organizers and community members to engage policymakers with the intention of making policy change on a local and/or statewide level. On the national level, PAN's Drift Catcher data has helped win regulatory recognition of volatilization drift for pesticides other than fumigants. Lessons learned from conducting community-based research projects will also be discussed. PAN is also currently assessing other community-based monitoring tools, such as community surveys and drift questionnaires that may allow communities to collect data that can also support the campaign work.

  11. New insights into the regulatory pathways associated with the activation of the stringent response in bacterial resistance to the PBP2-targeted antibiotics, mecillinam and OP0595/RG6080.

    Science.gov (United States)

    Doumith, M; Mushtaq, S; Livermore, D M; Woodford, N

    2016-10-01

    The diazabicyclooctane β-lactamase inhibitor OP0595 (RG6080) also acts as an antibiotic, targeting PBP2 in Enterobacteriaceae, but this activity is vulnerable to mutational resistance. We used WGS to investigate the basis of this resistance. Twenty OP0595-selected mutants, comprising four derived from each of five different Escherichia coli strains, were sequenced on Illumina HiSeq. Reads from each mutant were mapped to the assembled genome of the corresponding parent. A variant-calling file generated with Samtools was parsed to determine genetic alterations. Besides OP0595, the mutants consistently showed decreased susceptibility to mecillinam, which likewise targets PBP2, and grew as stable round forms in the presence of subinhibitory concentrations of OP0595. Among the 20 mutants, 18 had alterations in genes encoding tRNA synthase and modification functions liable to induce expression of the RpoS sigma factor through activation of the stringent response or had mutations suppressing inactivators of RpoS or the stringent response signal-degrading enzyme, SpoT. TolB was inactivated in one mutant: this activates RcsBC regulation and was previously associated with mecillinam resistance. The mechanism of resistance remained unidentified in one mutant. Both the RpoS and RcsBC systems regulate genes of cell division, including ftsAQZ that can compensate for loss or inhibition of PBP2, allowing survival of the challenged bacteria as stable round forms, as seen. WGS identified the global stringent response signal, entailing induction of RpoS, as the main mediator of mutational resistance to OP0595 in E. coli. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  12. Correcting sample drift using Fourier harmonics.

    Science.gov (United States)

    Bárcena-González, G; Guerrero-Lebrero, M P; Guerrero, E; Reyes, D F; Braza, V; Yañez, A; Nuñez-Moraleda, B; González, D; Galindo, P L

    2018-04-21

    During image acquisition of crystalline materials by high-resolution scanning transmission electron microscopy, the sample drift could lead to distortions and shears that hinder their quantitative analysis and characterization. In order to measure and correct this effect, several authors have proposed different methodologies making use of series of images. In this work, we introduce a methodology to determine the drift angle via Fourier analysis by using a single image based on the measurements between the angles of the second Fourier harmonics in different quadrants. Two different approaches, that are independent of the angle of acquisition of the image, are evaluated. In addition, our results demonstrate that the determination of the drift angle is more accurate by using the measurements of non-consecutive quadrants when the angle of acquisition is an odd multiple of 45°. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. The KLOE drift chamber VCI 2001

    CERN Document Server

    Adinolfi, M; Ambrosino, F; Andryakov, A; Antonelli, A; Antonelli, M; Anulli, F; Bacci, C; Bankamp, A; Barbiellini, G; Bellini, F; Bencivenni, G; Bertolucci, Sergio; Bini, C; Bloise, C; Bocci, V; Bossi, F; Branchini, P; Bulychjov, S A; Cabibbo, G; Calcaterra, A; Caloi, R; Campana, P; Capon, G; Carboni, G; Cardini, A; Casarsa, M; Cataldi, G; Ceradini, F; Cervell, F; Cevenini, F; Chiefari, G; Ciambrone, P; Conetti, S; Conticelli, S; De Lucia, E; De Robertis, G; De Simone, P; De Zorzi, G; De Sangro, R; Dell'Agnello, S; Denig, A; Di Domenico, A; Di Donato, C; Di Falco, S; Doria, A; Drago, E; Elia, V; Erriquez, O; Farilla, A; Felici, G; Ferrari, A; Ferrer, M L; Finocchiaro, G; Forti, C; Franceschi, A; Franzini, P; Gao, M L; Gatti, C; Gauzzi, P; Giovannella, S; Golovatyuk, V; Gorini, E; Grancagnolo, F; Grandegger, W; Graziani, E; Guarnaccia, P; Han, H G; Han, S W; Huang, X; Incagli, M; Ingrosso, L; Jang, Y Y; Kim, W; Kluge, W; Kulikov, V; Lacava, F; Lanfranchi, G; Lee-Franzini, J; Lomtadze, F; Luisi, C; Mao Chen Sheng; Martemyanov, M; Matsyuk, M; Mei, W; Merola, L; Messi, R; Miscetti, S; Moalem, A; Moccia, S; Moulson, M; Murtas, F; Müller, S; Napolitano, M; Nedosekin, A; Pacciani, L; Pagès, P; Palutan, M; Panareo, M; Paoluzi, L; Pasqualucci, E; Passalacqua, L; Passaseo, M; Passeri, A; Patera, V; Petrolo, E; Petrucci, Guido; Picca, D; Pirozzi, G; Pistillo, C; Pollack, M; Pontecorvo, L; Primavera, M; Ruggieri, F; Santangelo, P; Santovetti, E; Saracino, G; Schamberger, R D; Schwick, C; Sciascia, B; Sciubba, A; Scuri, F; Sfiligoi, I; Shan, J; Silano, P; Spadaro, T; Spagnolo, S; Spiriti, E; Stanescu, C; Tong, G L; Tortora, L; Valente, E; Valente, P; Valeriani, B; Venanzoni, G; Veneziano, Stefano; Von Hagel, U; Wu, Y; Xie, Y G; Zhao, P P; Zhou, Y

    2002-01-01

    The main goal of the KLOE experiment at the Frascati DAPHINE phi-factory is the study CP violation in kaon decays. The tracking device of the experiment is a drift chamber whose dimensions, 4 m of diameter and 3.3 m length, provide a large acceptance volume for the decay products of low momentum K sub L (lambda sub L =3.4 m). A complete stereo geometry with 12.582 cells arranged in 58 layers guarantees a high and uniform efficiency in the reconstruction of the charged K sub L decays. Very light materials have been chosen both for the drift medium, a helium-based gas mixture, and for the mechanical structure, made of carbon fiber, to minimize multiple scattering and conversion of low-energy photons. The design requirements, the adopted solutions together with the calibration procedure and the tracking performances of the drift chamber are discussed.

  14. The KLOE drift chamber VCI 2001

    International Nuclear Information System (INIS)

    Adinolfi, M.; Aloisio, A.; Ambrosino, F.; Andryakov, A.; Antonelli, A.; Antonelli, M.; Anulli, F.; Bacci, C.; Bankamp, A.; Barbiellini, G.; Bellini, F.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S.A.; Cabibbo, G.; Calcaterra, A.; Caloi, R.; Campana, P.; Capon, G.; Carboni, G.; Cardini, A.; Casarsa, M.; Cataldi, G.; Ceradini, F.; Cervell, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; Conticelli, S.; De Lucia, E.; De Robertis, G.; De Sangro, R.; De Simone, P.; De Zorzi, G.; Dell'Agnello, S.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Falco, S.; Doria, A.; Drago, E.; Elia, V.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M.L.; Finocchiaro, G.; Forti, C.; Franceschi, A.; Franzini, P.; Gao, M.L.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Golovatyuk, V.; Gorini, E.; Grancagnolo, F.; Grandegger, W.; Graziani, E.; Guarnaccia, P.; Hagel, U. von.; Han, H.G.; Han, S.W.; Huang, X.; Incagli, M.; Ingrosso, L.; Jang, Y.Y.; Kim, W.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Lomtadze, F.; Luisi, C.; Mao, C.S.; Martemianov, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moalem, A.; Moccia, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nedosekin, A.; Panareo, M.; Pacciani, L.; Pages, P.; Palutan, M.; Paoluzi, L.; Pasqualucci, E.; Passalacqua, L.; Passaseo, M.; Passeri, A.; Patera, V.; Petrolo, E.; Petrucci, G.; Picca, D.; Pirozzi, G.; Pistillo, C.; Pollack, M.; Pontecorvo, L.; Primavera, M.; Ruggieri, F.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R.D.; Schwick, C.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Shan, J.; Silano, P.; Spadaro, T.; Spagnolo, S.; Spiriti, E.; Stanescu, C.; Tong, G.L.; Tortora, L.; Valente, E.; Valente, P.; Valeriani, B.; Venanzoni, G.; Veneziano, S.; Wu, Y.; Xie, Y.G.; Zhao, P.P.; Zhou, Y.

    2002-01-01

    The main goal of the KLOE experiment at the Frascati DAPHINE phi-factory is the study CP violation in kaon decays. The tracking device of the experiment is a drift chamber whose dimensions, 4 m of diameter and 3.3 m length, provide a large acceptance volume for the decay products of low momentum K L (λ L =3.4 m). A complete stereo geometry with 12.582 cells arranged in 58 layers guarantees a high and uniform efficiency in the reconstruction of the charged K L decays. Very light materials have been chosen both for the drift medium, a helium-based gas mixture, and for the mechanical structure, made of carbon fiber, to minimize multiple scattering and conversion of low-energy photons. The design requirements, the adopted solutions together with the calibration procedure and the tracking performances of the drift chamber are discussed

  15. The implementation of modern digital technology in x-ray medical diagnosis in Republic of Moldova - a stringent necessity

    International Nuclear Information System (INIS)

    Rosca, Andrei

    2011-01-01

    The study includes analyses of current technical state of radiodiagnostic equipment from the Public Medico-Sanitary Institution of Ministry of Health of Republic of Moldova (IMSP MS RM). The traditional radiodiagnostic apparatuses were morally and physically outrun at 96,6% (in regional MSPI - 93,5%), inclusive the dental one - 92,0% (in raional MSPI - 97,2%), X-Ray exam -100%, mobile - 84,1% etc. The exploitation of the traditional radiodiagnostic apparatuses with high degree of physical and moral wear essentially diminished the quality of profile investigation, creates premises for diagnostic error perpetrating, increase the collective ionizing irradiation of population etc. In recent years the subvention of MSPI HM RM with digital radiodiagnostic equipment was started. This process is very hard unfold because of grave socio-economic crises in Republic of Moldova. Despite these obstacles the subvention of MSPI HM RM with digital equipment represents a stringent necessity and a time request.

  16. Global energy scenarios meeting stringent CO2 constraints - cost-effective fuel choices in the transportation sector

    International Nuclear Information System (INIS)

    Azar, Christian; Lindgren, Kristian; Andersson, B.A.

    2003-01-01

    The purpose of this paper is to assess fuel choices in the transportation sector under stringent global carbon constraints. Three key questions are asked: (i) when is it cost-effective to carry out the transition away from gasoline/diesel; (ii) to which fuel is it cost-effective to shift; and (iii) in which sector is biomass most cost-effectively used? These questions are analyzed using a global energy systems model (GET 1.0), with a transportation module, where vehicle costs (fuel cell, reformer and storage tank), infrastructure and primary energy availability are treated explicitly. The model is run under the assumption that atmospheric concentrations of CO 2 should be stabilized at 400 ppm. Three main results emerge: (i) despite the stringent CO 2 constraints, oil-based fuels remain dominant in the transportation sector over the next 50 years; and (ii) once a transition towards alternative fuels takes place, the preferred choice of fuel is hydrogen, even if we assume that hydrogen fuel cell vehicles are substantially more costly than methanol fuel cell vehicles. There may, under some circumstances, be a transient period of several decades with a significant share of methanol in the transportation sector. (iii) Biomass is most cost-effectively used in the heat and process heat sectors. If carbon sequestration from biomass is allowed, biomass is primarily used for hydrogen generation since small-scale heat applications are not suitable for carbon sequestration. Detailed sensitivity analyses show that these results are robust with respect to several parameters. Some policy conclusions are drawn

  17. Genetic drift suppresses bacterial conjugation in spatially structured populations

    OpenAIRE

    Freese, Peter D.; Korolev, Kirill S.; Jimenez, Jose I.; Chen, Irene A.

    2014-01-01

    Conjugation is the primary mechanism of horizontal gene transfer that spreads antibiotic resistance among bacteria. Although conjugation normally occurs in surface-associated growth (e.g., biofilms), it has been traditionally studied in well-mixed liquid cultures lacking spatial structure, which is known to affect many evolutionary and ecological processes. Here we visualize spatial patterns of gene transfer mediated by F plasmid conjugation in a colony of Escherichia coli growing on solid ag...

  18. Genetic drift. Overview of German, Nazi, and Holocaust medicine.

    Science.gov (United States)

    Cohen, M Michael

    2010-03-01

    An overview of German, Nazi, and Holocaust medicine brings together a group of subjects discussed separately elsewhere. Topics considered include German medicine before and during the Nazi era, such as advanced concepts in epidemiology, preventive medicine, public health policy, screening programs, occupational health laws, compensation for certain medical conditions, and two remarkable guidelines for informed consent for medical procedures; also considered are the Nuremberg Code; American models for early Nazi programs, including compulsory sterilization, abusive medical experiments on prison inmates, and discrimination against black people; two ironies in US and Nazi laws; social Darwinism and racial hygiene; complicity of Nazi physicians, including the acts of sterilization, human experimentation, and genocide; Nazi persecution of Jewish physicians; eponyms of unethical German physicians with particular emphasis on Reiter, Hallervorden, and Pernkopf; eponyms of famous physicians who were Nazi victims, including Pick and van Creveld; and finally, a recommendation for convening an international committee of physicians and ethicists to deal with five issues: (a) to propose alternative names for eponyms of physicians who exhibited complicity during the Nazi era; (b) to honor the eponyms and stories of physicians who were victims of Nazi atrocities and genocide; (c) to apply vigorous pressure to those German and Austrian Institutes that have not yet undertaken investigations to determine if the bodies of Nazi victims remain in their collections; (d) to recommend holding annual commemorations in medical schools and research institutes worldwide to remember and to reflect on the victims of compromised medical practice, particularly, but not exclusively, during the Nazi era because atrocities and acts of genocide have occurred elsewhere; and (e) to examine the influence of any political ideology that compromises the practice of medicine. (c) 2010 Wiley-Liss, Inc

  19. Morphological clines and weak drift along an urbanization gradient in the butterfly, Pieris rapae.

    Directory of Open Access Journals (Sweden)

    Sean D Schoville

    Full Text Available Urban areas are increasing globally, providing opportunities for biodiversity researchers to study the process in which species become established in novel, highly disturbed habitats. This ecological process can be understood through analyses of morphological and genetic variation, which can shed light on patterns of neutral and adaptive evolution. Previous studies have shown that urban populations often diverge genetically from non-urban source populations. This could occur due to neutral genetic drift, but an alternative is that selection could lead to allele frequency changes in urban populations. The development of genome scan methods provides an opportunity to investigate these outcomes from samples of genetic variation taken along an urbanization gradient. Here we examine morphological variation in wing size and diversity at neutral amplified fragment length polymorphisms in the butterfly Pieris rapae L. (Lepidoptera, Pieridae sampled from the center to the periphery of Marseille. We utilize established and novel environmental correlation approaches to scan genetic variation for evidence of selection. We find significant morphological differences in urban populations, as well as weak genetic structure and decreased genetic diversity in urban versus non-urban sites. However, environmental correlation tests provide little support for selection in our dataset. Our comparison of different methods and allele frequency clines suggests that loci identified as significant are false positives. Although there is some indication that selection may be acting on wing size in urban butterflies, genetic analyses suggest P. rapae are undergoing neutral drift.

  20. Continental drift under the Third Reich.

    Science.gov (United States)

    Buffetaut, Eric

    2003-12-01

    Contrary to what happened in many other countries in the 1930s and 1940s, Alfred Wegener's theory of continental drift was not generally rejected in Nazi Germany, although several leading German geologists of the time did not accept it. It was actually presented as the modern view of Earth history in books and magazine articles aimed at the general public. Although outlandish geological theories such as Hörbiger's Welteislehre were favoured by some Nazi dignitaries, they were not widely accepted in scientific circles. On the other hand, continental drift received official support under the Third Reich, at a time when it was ignored or ridiculed by most earth scientists outside Germany.

  1. Do the pyramids show continental drift?

    Science.gov (United States)

    Pawley, G S; Abrahamsen, N

    1973-03-02

    The mystery of the orientation of the Great Pyramids of Giza has remained unexplained for many decades. The general alignment is 4 minutes west of north. It is argued that this is not a builders' error but is caused by movement over the centuries. Modern theories of continental drift do not predict quite such large movements, but other causes of polar wandering give even smaller shifts. Thus, continental drift is the most likely explanation, although somewhat implausible, especially as relevant measurements have been made over a 50-year period, whereas geophysical measurements of sea-floor spreading relate to million-year time scales.

  2. Nonlinear dynamics of resistive electrostatic drift waves

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Michelsen, Poul; Pécseli, H.L.

    1999-01-01

    The evolution of weakly nonlinear electrostatic drift waves in an externally imposed strong homogeneous magnetic field is investigated numerically in three spatial dimensions. The analysis is based on a set of coupled, nonlinear equations, which are solved for an initial condition which is pertur......The evolution of weakly nonlinear electrostatic drift waves in an externally imposed strong homogeneous magnetic field is investigated numerically in three spatial dimensions. The analysis is based on a set of coupled, nonlinear equations, which are solved for an initial condition which...... polarity, i.e. a pair of electrostatic convective cells....

  3. Drifts of Dust or Something Else?

    Science.gov (United States)

    2004-01-01

    While the interior and far walls of the crater dubbed 'Bonneville' can be seen in the background, the dominant foreground features in this 180-degree navigation camera mosaic are the wind-deposited drifts of dust or sand. NASA's Mars Exploration Rover Spirit completed this mosaic on sol 71, March 15, 2004, from its newest location at the rim of 'Bonneville' crater. Scientists are interested in these formations in part because they might give insight into the processes that formed some of the material within the crater. Thermal emission measurements by the rover indicate that the dark material just below the far rim of this crater is spectrally similar to rocks that scientists have analyzed along their journey to this location. They want to know why this soil-like material has a spectrum that more closely resembles rocks rather than other soils examined so far. The drifts seen in the foreground of this mosaic might have the answer. Scientists hypothesize that these drifts might consist of wind-deposited particles that are the same as the dark material found against the back wall of the crater. If so, Spirit may spend time studying the material and help scientists understand why it is different from other fine-grained material seen at Gusev. The drifts appear to be lighter in color than the dark material deposited on the back wall of the crater. They might be covered by a thin deposit of martian dust, or perhaps the drift is like other drifts seen during Spirit's journey and is just a collection of martian dust. To find out, Spirit will spend some of sol 72 digging its wheels into the drift to uncover its interior. After backing up a bit, Spirit will use the panoramic camera and miniature thermal emission spectrometer to analyze the scuffed area. If the interior material has a similar spectrum to the dark deposit in the crater, then Spirit will most likely stay here a little longer to study the drift with the instruments on its robotic arm. If the material is uniform

  4. Nuclear controls are stringent

    International Nuclear Information System (INIS)

    Sonnekus, D.

    1983-01-01

    The peace-time application of nuclear power in South Africa, the organisations concerned and certain provisions laid down by the Act on Nuclear Energy, aimed at safeguarding the general public, are discussed

  5. Overcoming challenges in engineering the genetic code

    OpenAIRE

    Lajoie, MJ; Söll, D; Church, GM

    2015-01-01

    Withstanding 3.5 billion years of genetic drift, the canonical genetic code remains such a fundamental foundation for the complexity of life that it is highly conserved across all three phylogenetic domains. Genome engineering technologies are now making it possible to rationally change the genetic code, offering resistance to viruses, genetic isolation from horizontal gene transfer, and prevention of environmental escape by genetically modified organisms. We discuss the biochemical, genetic,...

  6. Equatorial ionospheric zonal drift model and vertical drift statistics from UHF scintillation measurements in South America

    Directory of Open Access Journals (Sweden)

    R. E. Sheehan

    2004-09-01

    Full Text Available UHF scintillation measurements of zonal ionospheric drifts have been conducted at Ancon, Peru since 1994 using antennas spaced in the magnetic east-west direction to cross-correlate geo-synchronous satellite signals. An empirical model of average drift over a wide range of Kp and solar flux conditions was constructed from successive two-dimensional fits of drift vs. the parameters and day of year. The model exhibits the typical local time trend of maximum eastward velocity in the early evening with a gradual decrease and reversal in the early morning hours. As expected, velocities at all hours increase with the solar flux and decrease with Kp activity. It was also found that vertical drifts could contribute to the variability of drift measurements to the east of Ancon at a low elevation angle. The vertical drift at the ionospheric intersection to the east can be estimated when combined with nearly overhead observations at Ancon or a similar spaced-antenna site at Antofagasta, Chile. Comparisons on five days with nearly simultaneous measurements of vertical drift by the Julia radar at Jicamarca, Peru show varying agreement with the spaced-antenna estimates. Statistical results from 1997 to 2001 generally agree with radar and satellite studies.

  7. Inducible Expression of Agrobacterium Virulence Gene VirE2 for Stringent Regulation of T-DNA Transfer in Plant Transient Expression Systems.

    Science.gov (United States)

    Denkovskienė, Erna; Paškevičius, Šarūnas; Werner, Stefan; Gleba, Yuri; Ražanskienė, Aušra

    2015-11-01

    Agrotransfection with viral vectors is an effective solution for the transient production of valuable proteins in plants grown in contained facilities. Transfection methods suitable for field applications are desirable for the production of high-volume products and for the transient molecular reprogramming of plants. The use of genetically modified (GM) Agrobacterium strains for plant transfections faces substantial biosafety issues. The environmental biosafety of GM Agrobacterium strains could be improved by regulating their T-DNA transfer via chemically inducible expression of virE2, one of the essential Agrobacterium virulence genes. In order to identify strong and stringently regulated promoters in Agrobacterium strains, we evaluated isopropyl-β-d-thiogalactoside-inducible promoters Plac, Ptac, PT7/lacO, and PT5/lacOlacO and cumic acid-inducible promoters PlacUV5/CuO, Ptac/CuO, PT5/CuO, and PvirE/CuO. Nicotiana benthamiana plants were transfected with a virE2-deficient A. tumefaciens strain containing transient expression vectors harboring inducible virE2 expression cassettes and containing a marker green fluorescent protein (GFP) gene in their T-DNA region. Evaluation of T-DNA transfer was achieved by counting GFP expression foci on plant leaves. The virE2 expression from cumic acid-induced promoters resulted in 47 to 72% of wild-type T-DNA transfer. Here, we present efficient and tightly regulated promoters for gene expression in A. tumefaciens and a novel approach to address environmental biosafety concerns in agrobiotechnology.

  8. Sub-micrometer-precision, three-dimensional (3D) hydrodynamic focusing via "microfluidic drifting".

    Science.gov (United States)

    Nawaz, Ahmad Ahsan; Zhang, Xiangjun; Mao, Xiaole; Rufo, Joseph; Lin, Sz-Chin Steven; Guo, Feng; Zhao, Yanhui; Lapsley, Michael; Li, Peng; McCoy, J Philip; Levine, Stewart J; Huang, Tony Jun

    2014-01-21

    In this article, we demonstrate single-layered, "microfluidic drifting" based three-dimensional (3D) hydrodynamic focusing devices with particle/cell focal positioning approaching submicron precision along both lateral and vertical directions. By systematically optimizing channel geometries and sample/sheath flow rates, a series of "microfluidic drifting" based 3D hydrodynamic focusing devices with different curvature angles are designed and fabricated. Their performances are then evaluated using confocal microscopy, fast camera imaging, and side-view imaging techniques. Using a device with a curvature angle of 180°, we have achieved a standard deviation of ±0.45 μm in particle focal position and a coefficient of variation (CV) of 2.37% in flow cytometric measurements. To the best of our knowledge, this is the best CV that has been achieved using a microfluidic flow cytometry device. Moreover, the device showed the capability to distinguish 8 peaks when subjected to a stringent 8-peak rainbow calibration test, signifying the ability to perform sensitive, accurate tests similar to commercial flow cytometers. We have further tested and validated our device by detection of HEK-293 cells. With its advantages in simple fabrication (i.e., single-layered device), precise 3D hydrodynamic focusing (i.e., submicrometer precision along both lateral and vertical directions), and high detection resolution (i.e., low CV), our method could serve as an important basis for high-performance, mass-producible microfluidic flow cytometry.

  9. Wegener and his Theory of Continental Drift

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 7. Wegener and his Theory of Continental Drift. Ramesh Chander. General Article Volume 4 Issue 7 July 1999 pp 24-41. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/004/07/0024-0041 ...

  10. Comment on the drift mirror instability

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr

    2008-01-01

    Roč. 15, č. 5 (2008), 054502/1-054502/2 ISSN 1070-664X R&D Projects: GA AV ČR IAA300420702 Institutional research plan: CEZ:AV0Z30420517 Keywords : drift mirror instability * linear theory Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.427, year: 2008

  11. Plate Tectonics and Continental Drift: Classroom Ideas.

    Science.gov (United States)

    Stout, Prentice K.

    1983-01-01

    Suggests various classroom studies related to plate tectonics and continental drift, including comments on and sources of resource materials useful in teaching the topics. A complete list of magazine articles on the topics from the Sawyer Marine Resource Collection may be obtained by contacting the author. (JN)

  12. Wegener and his Theory of Continental Drift

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 12. Wegener and his Theory of Continental Drift. Ramesh Chander. Volume 10 Issue 12 December 2005 pp 58-75. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/010/12/0058-0075 ...

  13. Backward stochastic differential equations with Young drift

    OpenAIRE

    Diehl, Joscha; Zhang, Jianfeng

    2016-01-01

    We prove via a direct fixpoint argument the well-posedness of backward stochastic differential equations containing an additional drift driven by a path of finite $p$-variation with $p \\in [1,2)$. An application to the Feynman-Kac representation of semilinear rough partial differential equations is given.

  14. Psychometric Consequences of Subpopulation Item Parameter Drift

    Science.gov (United States)

    Huggins-Manley, Anne Corinne

    2017-01-01

    This study defines subpopulation item parameter drift (SIPD) as a change in item parameters over time that is dependent on subpopulations of examinees, and hypothesizes that the presence of SIPD in anchor items is associated with bias and/or lack of invariance in three psychometric outcomes. Results show that SIPD in anchor items is associated…

  15. Fine structure in fast drift storm bursts

    International Nuclear Information System (INIS)

    McConnell, D.; Ellis, G.R.A.

    1981-01-01

    Recent observations with high time resolution of fast drift storm (FDS) solar bursts are described. A new variety of FDS bursts characterised by intensity maxima regularly placed in the frequency domain is reported. Possible interpretations of this are mentioned and the implications of the short duration of FDS bursts are discussed. (orig.)

  16. Low-Drift Micro Flow Sensors

    NARCIS (Netherlands)

    Dijkstra, Marcel

    2009-01-01

    The emerging fields of micro total-analysis systems (micro-TAS), micro-reactors and bio-MEMS drives the need for further miniaturisation of sensors measuring quantities such as pressure, temperature and flow. The research described in this thesis concerns the development of low-drift micro flow

  17. DRIFT PATTERNS OF ANCHOVY ENGRAULIS CAPENSIS ...

    African Journals Online (AJOL)

    In the southern Benguela, successful recruitment of Cape anchovy Engraulis capensis is highly variable and seems to be dependent on the spawning biomass only to a small extent. This paper investigates how the variations in the drift patterns of larvae from the spawning areas on the Agulhas Bank to the ...

  18. Drift wave in pair-ion plasma

    Indian Academy of Sciences (India)

    ion plasma are discussed. It is shown that the temperature and/or mass difference of both species could produce drift wave in a pair-ion plasma. The results are discussed in the context of the fullerene pair-ion plasma experiment.

  19. Resistive drift wave turbulence and transport

    International Nuclear Information System (INIS)

    Wakatani, M.

    1986-01-01

    Our efforts for studying the properties of resistive drift wave turbulence by using model mode-coupling equations are shown. It may be related to the edge turbulence and the associated anomalous transport in tokamaks or in stellarator/heliotron. (author)

  20. Learning drifting concepts with neural networks

    NARCIS (Netherlands)

    Biehl, Michael; Schwarze, Holm

    1993-01-01

    The learning of time-dependent concepts with a neural network is studied analytically and numerically. The linearly separable target rule is represented by an N-vector, whose time dependence is modelled by a random or deterministic drift process. A single-layer network is trained online using

  1. Study and analysis of drift chamber parameters

    International Nuclear Information System (INIS)

    Martinez Laso, L.

    1988-01-01

    The present work deals mainly with drift chambers. In the first chapter a summary of drift chamber properties is presented. The information has been collected from the extensive bibliography available in this field. A very simple calculation procedure of drift chamber parameters has been developed and is presented in detail in the second chapter. Some prototypes have been made following two geometries (multidrift chamber and Z-chambers). Several installations have been used for test and calibration of these prototypes. A complete description of these installations is given in the third chapter. Cosmic rays, beta particles from a Ru106 radiactive source and a test beam in the WA (West Area) of SPS at CERN have been used for experimental purposes. The analysis and the results are described for the different setups. The experimental measurements have been used to produce a complete cell parametrization (position as function of drift time) and to obtain spatial resolution values (in the range of 200-250 um). Experimental results are in good agreement with numerical calculations. (Author)

  2. Sealed drift tube cosmic ray veto counters

    Energy Technology Data Exchange (ETDEWEB)

    Rios, R., E-mail: rrios@lanl.go [Idaho State University, Pocatello, ID 83209 (United States); Tatar, E. [Idaho State University, Pocatello, ID 83209 (United States); Bacon, J.D.; Bowles, T.J.; Hill, R.; Green, J.A.; Hogan, G.E.; Ito, T.M.; Makela, M.; Morris, C.L.; Mortenson, R.; Pasukanics, F.E.; Ramsey, J.; Saunders, A.; Seestrom, S.J.; Sondheim, W.E.; Teasdale, W. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Saltus, M. [Sloan Enterprises, NC (United States); Back, H.O.; Cottrell, C.R. [North Carolina State University, Raleigh, NC 27695 (United States)

    2011-05-01

    We describe a simple drift tube counter that has been used as a cosmic ray veto for the UCNA experiment, a first-ever measurement of the neutron beta-asymmetry using ultra-cold neutrons. These detectors provide an inexpensive alternative to more conventional scintillation detectors for large area cosmic ray anticoincidence detectors.

  3. A drift chamber with uniform electric field and measurements of the electron drift velocity

    International Nuclear Information System (INIS)

    Ma Chimao; Mao Zepu; Zhou Jie; Yan Jie

    1985-01-01

    The measurements of the electron drift velocity as a function of the electric field have been made in a small drift chamber with uniform electric field for Ar/CH 4 , Ar/i-C 4 H 10 , Ar/CO 2 and SQS gas mixtures. The values of the electric field range from about 0.3 to 2.5 kV/cm. The results of the measurements are discussed

  4. Drift chamber with uniform electric field and measurements of the electron drift velocity

    International Nuclear Information System (INIS)

    MA Chi-mao; MAO Ze-pu; ZHOU Jie; YAN Jie

    1985-01-01

    Measurements of the electron drift velocity as a function of the electric field have been made in a small drift chamber with uniform electric field for Ar/CH 4 , Ar/i-C 4 H 10 , Ar/CO 2 , and SQS gas mixtures. The value of the electric field ranges from about 0.3 to 2.5 kV/cm. The results of the measurements are discussed

  5. The Effects of Clock Drift on the Mars Exploration Rovers

    Science.gov (United States)

    Ali, Khaled S.; Vanelli, C. Anthony

    2012-01-01

    All clocks drift by some amount, and the mission clock on the Mars Exploration Rovers (MER) is no exception. The mission clock on both MER rovers drifted significantly since the rovers were launched, and it is still drifting on the Opportunity rover. The drift rate is temperature dependent. Clock drift causes problems for onboard behaviors and spacecraft operations, such as attitude estimation, driving, operation of the robotic arm, pointing for imaging, power analysis, and telecom analysis. The MER operations team has techniques to deal with some of these problems. There are a few techniques for reducing and eliminating the clock drift, but each has drawbacks. This paper presents an explanation of what is meant by clock drift on the rovers, its relationship to temperature, how we measure it, what problems it causes, how we deal with those problems, and techniques for reducing the drift.

  6. Barber's Point, Oahu, Hawaii Drift Card Study 2002-2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drift cards were be released from Barber's Point, Oahu, approximately once a month during the two year span to get an idea of the distribution of card drift under...

  7. Drift-Scale THC Seepage Model

    International Nuclear Information System (INIS)

    C.R. Bryan

    2005-01-01

    The purpose of this report (REV04) is to document the thermal-hydrologic-chemical (THC) seepage model, which simulates the composition of waters that could potentially seep into emplacement drifts, and the composition of the gas phase. The THC seepage model is processed and abstracted for use in the total system performance assessment (TSPA) for the license application (LA). This report has been developed in accordance with ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Post-Processing Analysis for THC Seepage) Report Integration'' (BSC 2005 [DIRS 172761]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this report. The plan for validation of the models documented in this report is given in Section 2.2.2, ''Model Validation for the DS THC Seepage Model,'' of the TWP. The TWP (Section 3.2.2) identifies Acceptance Criteria 1 to 4 for ''Quantity and Chemistry of Water Contacting Engineered Barriers and Waste Forms'' (NRC 2003 [DIRS 163274]) as being applicable to this report; however, in variance to the TWP, Acceptance Criterion 5 has also been determined to be applicable, and is addressed, along with the other Acceptance Criteria, in Section 4.2 of this report. Also, three FEPS not listed in the TWP (2.2.10.01.0A, 2.2.10.06.0A, and 2.2.11.02.0A) are partially addressed in this report, and have been added to the list of excluded FEPS in Table 6.1-2. This report has been developed in accordance with LP-SIII.10Q-BSC, ''Models''. This report documents the THC seepage model and a derivative used for validation, the Drift Scale Test (DST) THC submodel. The THC seepage model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral alteration on flow in rocks surrounding drifts. The DST THC submodel uses a drift

  8. Drift-Scale THC Seepage Model

    Energy Technology Data Exchange (ETDEWEB)

    C.R. Bryan

    2005-02-17

    The purpose of this report (REV04) is to document the thermal-hydrologic-chemical (THC) seepage model, which simulates the composition of waters that could potentially seep into emplacement drifts, and the composition of the gas phase. The THC seepage model is processed and abstracted for use in the total system performance assessment (TSPA) for the license application (LA). This report has been developed in accordance with ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Post-Processing Analysis for THC Seepage) Report Integration'' (BSC 2005 [DIRS 172761]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this report. The plan for validation of the models documented in this report is given in Section 2.2.2, ''Model Validation for the DS THC Seepage Model,'' of the TWP. The TWP (Section 3.2.2) identifies Acceptance Criteria 1 to 4 for ''Quantity and Chemistry of Water Contacting Engineered Barriers and Waste Forms'' (NRC 2003 [DIRS 163274]) as being applicable to this report; however, in variance to the TWP, Acceptance Criterion 5 has also been determined to be applicable, and is addressed, along with the other Acceptance Criteria, in Section 4.2 of this report. Also, three FEPS not listed in the TWP (2.2.10.01.0A, 2.2.10.06.0A, and 2.2.11.02.0A) are partially addressed in this report, and have been added to the list of excluded FEPS in Table 6.1-2. This report has been developed in accordance with LP-SIII.10Q-BSC, ''Models''. This report documents the THC seepage model and a derivative used for validation, the Drift Scale Test (DST) THC submodel. The THC seepage model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral

  9. Electromagnetic drift modes in an inhomogeneous electron gas

    DEFF Research Database (Denmark)

    Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

    1986-01-01

    A pair of nonlinear equations is derived which describes the dynamics of the electromagnetic drift oscillations in a nonuniform magnetized electron gas. It is shown that the nonlinear electromagnetic drift modes can propagate in the form of dipole vortices......A pair of nonlinear equations is derived which describes the dynamics of the electromagnetic drift oscillations in a nonuniform magnetized electron gas. It is shown that the nonlinear electromagnetic drift modes can propagate in the form of dipole vortices...

  10. Are Dutch residents ready for a more stringent policy to enhance the energy performance of their homes?

    International Nuclear Information System (INIS)

    Middelkoop, Manon van; Vringer, Kees; Visser, Hans

    2017-01-01

    Investments in the energy performance of houses offer good prospects for reducing energy consumption and CO 2 emissions. However, people are not easily convinced of the need to take measures to improve the energy performance of their houses, even when financial benefits outweigh the costs. This article analyses the factors that influence the decision for improving the energy performance of existing homes, including policy instruments. Subsequently, the article provides policy suggestions on how to stimulate energy performance improvements. Both owners and tenants (50–70%) support government policy on energy performance improvements to existing homes. Nevertheless, people also have strong feelings of autonomy regarding their homes. Our results underline the importance of well-informed and competent decision-makers. Introducing the use of Energy Performance Certificates (EPCs) into the tax system for energy and residential buildings might therefore be an effective way to increase the interest of owners in the EPC, improve the use and effect of this informative instrument, and make the first step towards bridging the tension between autonomy and more stringent instruments.

  11. Journal of Genetics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    East Asian Drosophila melanogaster are known for great variation in morphological and physiological characters among populations, variation that is believed to be maintained by genetic drift. To understand the genetic properties of Asian D. melanogaster populations, we initiated a population genetic study of chromosome ...

  12. Longevity of Emplacement Drift Ground Support Materials

    Energy Technology Data Exchange (ETDEWEB)

    Tang, David H.

    2001-05-30

    The purpose of this analysis is to evaluate the factors affecting the longevity of emplacement drift ground support materials and to develop a basis for the selection of materials for ground support that will function throughout the preclosure period of a potential repository at Yucca Mountain. REV 01 ICN 01 of this analysis is developed in accordance with AP-3.10Q, Analyses and Models, Revision 2, ICN 4, and prepared in accordance with the Technical Work Plan for Subsurface Design Section FY 01 Work Activities (CRWMS M&O 2001a). The objective of this analysis is to update the previous analysis (CRWMS M&O 2000a) to account for related changes in the Ground Control System Description Document (CRWMS M&O 2000b), the Monitored Geologic Repository Project Description Document, which is included in the Requirements and Criteria for Implementing a Repository Design that can be Operated Over a Range of Thermal Modes (BSC 2001), input information, and in environmental conditions, and to provide updated information on candidate ground support materials. Candidate materials for ground support are carbon steel and cement grout. Steel is mainly used for steel sets, lagging, channel, rock bolts, and wire mesh. Cement grout is only considered in the case of grouted rock bolts. Candidate materials for the emplacement drift invert are carbon steel and granular natural material. Materials are evaluated for the repository emplacement drift environment based on the updated thermal loading condition and waste package design. The analysis consists of the following tasks: (1) Identify factors affecting the longevity of ground support materials for use in emplacement drifts. (2) Review existing documents concerning the behavior of candidate ground support materials during the preclosure period. (3) Evaluate impacts of temperature and radiation effects on mechanical and thermal properties of steel. Assess corrosion potential of steel at emplacement drift environment. (4) Evaluate factors

  13. Toroidal effects on drift wave turbulence

    Energy Technology Data Exchange (ETDEWEB)

    LeBrun, M.J.; Tajima, T.; Gray, M.G.; Furnish, G.; Horton, W.

    1992-09-23

    The universal drift instability and other drift instabilities driven by density and temperature gradients in a toroidal system are investigated in both linear and nonlinear regimes via particle simulation. Runs in toroidal and cylindrical geometry show dramatic differences in plasma behavior, primarily due to the toroidicity-induced coupling of rational surfaces through the poloidal mode number m. In the toroidal system studied, the eigenmodes are seen to possess (i) an elongated, nearly global radial extent (ii) a higher growth rate than in the corresponding cylindrical system, (iii) an eigenfrequency nearly constant with radius, (iv) a global temperature relaxation and enhancement of thermal heat conduction. Most importantly, the measured Xi shows an increase with radius and an absolute value on the order of that observed in experiment. On the basis of our observations, we argue that the increase in Xi with radius observed in experiment is caused by the global nature of heat convection in the presence of toroidicity-induced mode coupling.

  14. Passive appendages generate drift through symmetry breaking

    Science.gov (United States)

    Lācis, U.; Brosse, N.; Ingremeau, F.; Mazzino, A.; Lundell, F.; Kellay, H.; Bagheri, S.

    2014-10-01

    Plants and animals use plumes, barbs, tails, feathers, hairs and fins to aid locomotion. Many of these appendages are not actively controlled, instead they have to interact passively with the surrounding fluid to generate motion. Here, we use theory, experiments and numerical simulations to show that an object with a protrusion in a separated flow drifts sideways by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in a fluid flow is unstable and how it stabilizes either to the left or right of the incoming flow direction. It is plausible that organisms with appendages in a separated flow use this newly discovered mechanism for locomotion; examples include the drift of plumed seeds without wind and the passive reorientation of motile animals.

  15. Improved coincidence rejection for silicon drift detectors

    Science.gov (United States)

    Mott, Richard B.

    2010-12-01

    The high count rates possible with silicon drift detectors (SDDs) raise the importance of coincidence ("pile-up") rejection in the pulse processor. Detection efficiency for close coincidence is energy dependent, with resolving times increasing sharply when at least one X-ray of the pair is below 1 keV. Traditional pile-up detection for low energies is done by applying a width test to the output of a shaping filter. SDDs have varying rise times at the preamplifier output due to the expansion of the charge cloud with drift path length, which limits the effectiveness of pulse width testing. Novel digital methods have been developed, which are largely immune to variations in rise time and significantly improve pulse-pair resolving times. Digital pulse processor filter parameters must take resolving times into account to achieve good sum peak position and shape for optimum software removal of sum peak artifacts during spectrum post-processing.

  16. Hole drift mobility in poly(hexylphenylsilane)

    International Nuclear Information System (INIS)

    Kunimi, Y.; Seki, S.; Tagawa, S.

    2000-01-01

    Poly(n-alkylphenylsilane)s in which n-alkyl were changed from methyl to octyl were polymerized. Hole transport properties of poly(alkyllphenylsilane)s were systematically studied by the DC time-of-flight (TOF) technique. While the hole drift mobility of poly(methylphenylsilane) increased monotonously in entire field, those of poly(hexylphenylsilane) and poly(octylphenylsilane) decreased with increase in the field strength. Temperature dependence of hole drift mobility in those polymers was small. On the basis of Baessler's disorder formalism the mobility was analyzed quantitatively to disserve complex contributions of charge transport. The analyzed results indicated that with increase in the length of n-alkyl side-groups, the energetic disorder of hopping sites became smaller and the disorder of distance between hopping sites became larger. These results were supported by the results obtained by UV absorption measurement and positron annihilation life-time spectroscopy measurement. (author)

  17. Clean Industrial Room for Drift Tube Assembling

    CERN Document Server

    Glonti, GL; Evtoukhovitch, P G; Kroa, G; Manz, A; Potrap, I N; Rihter, P; Stoletov, G D; Tskhadadze, E G; Chepurnov, V F; Chirkov, A V; Shelkov, G A

    2001-01-01

    Description of a clean industrial room for assembly of drift tubes for the muon spectrometer of the ATLAS experiment is presented. High quality specifications on the detectors to be produced demanded creation of a workplace with stable temperature and humidity, as well as minimum quantity of dust in the room. Checking of parameters of intra-room air during long period of continuous work has been confirmed correctness of the designed characteristics of the climatic system installed in the clean room. The room large volum (\\sim 190 m^3), the powerful and flexible climatic system, and simplicity of service allow assembling of detectors with length up to 5 m. Subsequent checking of functionality of the assembled detectors has shown high quality of assembling (the amount of rejected tubes does not exceed 2 %). It demonstrates conformity to the assembling quality requirements for mass production of drift chambers for the muon spectrometer.

  18. Gas sensor with attenuated drift characteristic

    Science.gov (United States)

    Chen, Ing-Shin [Danbury, CT; Chen, Philip S. H. [Bethel, CT; Neuner, Jeffrey W [Bethel, CT; Welch, James [Fairfield, CT; Hendrix, Bryan [Danbury, CT; Dimeo, Jr., Frank [Danbury, CT

    2008-05-13

    A sensor with an attenuated drift characteristic, including a layer structure in which a sensing layer has a layer of diffusional barrier material on at least one of its faces. The sensor may for example be constituted as a hydrogen gas sensor including a palladium/yttrium layer structure formed on a micro-hotplate base, with a chromium barrier layer between the yttrium layer and the micro-hotplate, and with a tantalum barrier layer between the yttrium layer and an overlying palladium protective layer. The gas sensor is useful for detection of a target gas in environments susceptible to generation or incursion of such gas, and achieves substantial (e.g., >90%) reduction of signal drift from the gas sensor in extended operation, relative to a corresponding gas sensor lacking the diffusional barrier structure of the invention

  19. KEYNOTE ADDRESS: CONSERVATION GENETICS OF FRESHWATER ORGANISMS

    OpenAIRE

    WEISS S.

    2005-01-01

    This manuscript serves as a summary of both the importance of genetics in conservation, and the range of methodological approaches available. Two somewhat distinct realms of conservation genetics are outlined. The first theoretically rests upon the field of population genetics, and primarily concerns itself with the conservation of genetic diversity within and among populations, both in the wild and captivity. Basic concepts such as heterozygosity, genetic drift, and effective population size...

  20. Cathode readout with stripped resistive drift tubes

    International Nuclear Information System (INIS)

    Bychkov, V.N.; Kekelidze, G.D.; Novikov, E.A.; Peshekhonov, V.D.; Shafranov, M.D.; Zhiltsov, V.E.

    1995-01-01

    A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with a carbon layer with a resistivity of 0.5, 30 and 70 kΩ/□. Both the anode wire and the cathode strip signals were detected to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented. (orig.)

  1. Unintended Positional Drift and Its Potential Solutions

    DEFF Research Database (Denmark)

    Nilsson, Niels Christian; Serafin, Stefania; Nordahl, Rolf

    2013-01-01

    Walking-In-Place interaction techniques seem particularly useful in relation to immersive virtual environments where the user's movement is greatly constrained by a limited physical space. However, current techniques may not be particularly useful in combination with head-mounted displays since...... many users unintentionally move forward while walking in place. We refer to this phenomenon accidental movement as Unintended Positional Drift. The poster presents evidence of the phenomenon's existence and subsequently discusses different design solutions which potentially could circumvent the problem....

  2. Drift Wave Simulations with Reduced Stellarator Equilibria

    International Nuclear Information System (INIS)

    J.L.V. Lewandowski

    1999-01-01

    A three-field model to study drift-resistive, low-frequency waves in low-beta, non-axisymmetric plasmas [J.L.V. Lewandowski, Phys. Plasmas, 4 (11) 4023 (1997)] is used to analyze the effect of the inhomogeneities in the stellarator magnetic field on the fastest (linear) growth rate, gamma. Extensive numerical calculations for a toroidal heliac show that not all Fourier components in the representation of the equilibrium configuration are important as far as gamma is concerned

  3. Cylindrical geometry for proportional and drift chambers

    International Nuclear Information System (INIS)

    Sadoulet, B.

    1975-06-01

    For experiments performed around storage rings such as e + e - rings or the ISR pp rings, cylindrical wire chambers are very attractive. They surround the beam pipe completely without any dead region in the azimuth, and fit well with the geometry of events where particles are more or less spherically produced. Unfortunately, cylindrical proportional or drift chambers are difficult to make. Problems are discussed and two approaches to fabricating the cathodes are discussed. (WHK)

  4. Spin-drift transport in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M Idrish [Nanoscale Science and Technology Centre and School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong, Chittagong-4331 (Bangladesh)

    2008-02-07

    We present a study on spin transport in semiconductors under applied electric fields. Our experiments detect photoinjected electron spins and their relaxation during drift transport in intrinsic and moderately n-doped GaAs, based on the extraordinary Hall (eH) effect. For relatively low electric field (E), the optically spin-induced eH effect in n-doped GaAs is found to be enhanced with increasing doping density and not to depend much on E, indicating that a substantial amount of optical spin polarization is preserved during the drift transport in these extrinsic semiconductors. However, when the spin-oriented electrons are injected with a high E, a very significant decrease is observed in the eH voltage (V{sub eH}) due to an increase in the spin precession frequency of the hot electrons. Spin relaxation by the D'yakonov-Perel' mechanism is calculated, and is suggested to be the reason for such a rapid spin relaxation for hot electrons under a high E. However, in an intrinsic GaAs (i-GaAs), a much weaker V{sub eH} is observed and, as the electron spins scattered by holes due to the Coulomb interaction in i-GaAs, the spin relaxation by the Bir-Aronov-Pikus mechanism is considered. Skew scattering and side jump as possible mechanisms of the optically spin-induced transverse Hall currents are discussed. Based on a spin drift-diffusion model, drift and diffusion contributions to the V{sub eH} are examined. The results are also discussed in comparison with theoretical investigations.

  5. Continued Drift, but without the Acrimony

    DEFF Research Database (Denmark)

    Nielsen, Kristian L.

    2013-01-01

    If the measure of Barack Obama's success in mending US–European relations is whether the tone has improved, his presidency has been a great success. If the measure of success, however, is halting the drifting apart of policy preferences, the picture looks a lot less rosy. This article argues....... The Obama administration realises that, and by this more limited measure, it has succeeded brilliantly....

  6. Diffusion by Infragravity Stokes Drift Fluctuations

    Science.gov (United States)

    Smit, P.; Janssen, T. T.; Herbers, T. H. C.; Kirshner, Z.

    2016-02-01

    The group-scale variability of ocean waves variability drives infragravity Stokes drift fluctuations, which are important for small-scale diffusion of passive tracers (to the order of a few kilometers), and can thus be important for the break-up and dispersion of e.g. oil spills or sewage outflow, and coastal transport in general. The implications of this were first considered theoretically by Herterich and Hasselmann (1982, JPO), who demonstrated that on small scales, wave diffusion can compete with other upper ocean diffusive processes, but their theory has thus far not been extensively validated with field observations. To investigate drift fluctuations and wave-induced diffusion, we consider the wave-induced dispersion of a cluster of O(10) buoys. The experiment, conducted offshore of San Francisco, uses a cluster of Lagrangian drifters equipped with fast-sampling GPS sensor packages, to accurately resolve both the surface wave motions, and directly measure the Lagrangian dynamics, including surface drift fluctuations. We revisit the Herterich and Hasselmann theory, expand it to include shallow water and variable wave conditions, and compare the theoretical predictions with the new observations.

  7. Internal Clock Drift Estimation in Computer Clusters

    Directory of Open Access Journals (Sweden)

    Hicham Marouani

    2008-01-01

    Full Text Available Most computers have several high-resolution timing sources, from the programmable interrupt timer to the cycle counter. Yet, even at a precision of one cycle in ten millions, clocks may drift significantly in a single second at a clock frequency of several GHz. When tracing the low-level system events in computer clusters, such as packet sending or reception, each computer system records its own events using an internal clock. In order to properly understand the global system behavior and performance, as reported by the events recorded on each computer, it is important to estimate precisely the clock differences and drift between the different computers in the system. This article studies the clock precision and stability of several computer systems, with different architectures. It also studies the typical network delay characteristics, since time synchronization algorithms rely on the exchange of network packets and are dependent on the symmetry of the delays. A very precise clock, based on the atomic time provided by the GPS satellite network, was used as a reference to measure clock drifts and network delays. The results obtained are of immediate use to all applications which depend on computer clocks or network time synchronization accuracy.

  8. Monitored Drift Chambers in the ATLAS Detector

    CERN Multimedia

    Herten, G

    Monitored Drift Chambers (MDT) are used in the ATLAS Detector to measure the momentum of high energy muons. They consist of drift tubes, which are filled with an Ar-CO2 gas mixture at 3 bar gas pressure. About 1200 drift chambers are required for ATLAS. They are up to 6 m long. Nevertheless the position of every wire needs to be known with a precision of 20 µm within a chamber. In addition, optical alignment sensors are required to measure the relative position of adjacent chambers with a precision of 30µm. This gigantic task seems impossible at first instance. Indeed it took many years of R&D to invent the right tools and methods before the first chamber could be built according to specifications. Today, at the time when 50% of the chambers have been produced, we are confident that the goal for ATLAS can be reached. The mechanical precision of the chambers could be verified with the x-ray tomograph at CERN. This ingenious device, developed for the MDT system, is able to measure the wire position insid...

  9. Adjustable rare earth quadrupole drift tube magnets

    International Nuclear Information System (INIS)

    Feinberg, B.; Tanabe, J.; Halbach, K.; Koehler, G.; Green, M.I.

    1987-03-01

    A prototype permanent-magnet drift tube quadrupole with adjustable field strength has been constructed and tested. The magnet uses iron pole pieces to provide the required field shape along with rare earth permanent-magnet material (samarium cobalt) to energize the magnet. A unique feature of the configuration is the adjustability of the field, accomplished by rotating the outer rings consisting of permanent magnets and iron. In contrast with a previous prototype magnet, this new design uses ball bearings in place of slide bearings to eliminate potential failures. The rotation is now achieved with a bevel gear mechanism. The prototype design also incorporates a new drift tube shell vacuum seal to allow easy disassembly. Tests were made of the magnetic properties and the mechanical performance of this magnet. Field errors are extremely small, and the magnet passed an accelerated ten year lifetime test. It is planned to use this type of magnet to replace 24 of the SuperHILAC prestripper drift tubes

  10. Longevity of Emplacement Drift Ground Support Materials

    International Nuclear Information System (INIS)

    Tang, D.

    2000-01-01

    The purpose of this analysis is to evaluate the factors affecting the longevity of emplacement drift ground support materials and to develop a basis for selection of materials for ground support that will function throughout the preclosure period. The Development Plan (DP) for this analysis is given in CRWMS M and O (Civilian Radioactive Waste Management System Management and Operating Contractor) (1999a). The candidate materials for ground support are steel (carbon steel, ductile cast iron, galvanized steel, and stainless steel, etc.) and cement. Steel will mainly be used for steel sets, lagging, channels, rock bolts, and wire mesh. Cement usage is only considered in the case of grouted rock bolts. The candidate materials for the invert structure are steel and crushed rock ballast. The materials shall be evaluated for the repository emplacement drift environment under a specific thermal loading condition based on the proposed License Application Design Selection (LADS) design. The analysis consists of the following tasks: (1) Identify factors affecting the longevity of ground control materials for use in emplacement drifts. (2) Review existing documents concerning behavior of candidate ground control materials during the preclosure period. The major criteria to be considered for steel are mechanical and thermal properties, and durability, of which corrosion is the most important concern. (3) Evaluate the available results and develop recommendations for material(s) to be used

  11. Transient chaotic transport in dissipative drift motion

    Energy Technology Data Exchange (ETDEWEB)

    Oyarzabal, R.S. [Pós-Graduação em Ciências/Física, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Szezech, J.D. [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Batista, A.M., E-mail: antoniomarcosbatista@gmail.com [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Souza, S.L.T. de [Departamento de Física e Matemática, Universidade Federal de São João del Rei, 36420-000, Ouro Branco, MG (Brazil); Caldas, I.L. [Instituto de Física, Universidade de São Paulo, 05315-970, São Paulo, SP (Brazil); Viana, R.L. [Departamento de Física, Universidade Federal do Paraná, 81531-990, Curitiba, PR (Brazil); Sanjuán, M.A.F. [Departamento de Física, Universidad Rey Juan Carlos, Tulipán s/n, 28933 Móstoles, Madrid (Spain)

    2016-04-22

    Highlights: • We consider a situation for which a chaotic transient is present in the dynamics of the two-wave model with damping. • The damping in plasma models can be a way for study a realistic behavior of confinement due the collisional effect. • The escape time as a function of the damping obey a power-law scaling. • We have made a qualitative transport analysis with a simple model that can be useful for more complete models. • We have shown that the pattern of the basin of attraction depends on the damping parameter. - Abstract: We investigate chaotic particle transport in magnetised plasmas with two electrostatic drift waves. Considering dissipation in the drift motion, we verify that the removed KAM surfaces originate periodic attractors with their corresponding basins of attraction. We show that the properties of the basins depend on the dissipation and the space-averaged escape time decays exponentially when the dissipation increases. We find positive finite time Lyapunov exponents in dissipative drift motion, consequently the trajectories exhibit transient chaotic transport. These features indicate how the transient plasma transport depends on the dissipation.

  12. A meta-analysis on the effects of 2,4-D and dicamba drift on soybean and cotton

    Science.gov (United States)

    Commercial introduction of cultivars of soybean and cotton genetically modified with resistance to the synthetic-auxin herbicides dicamba and 2,4-D will allow these compounds to be used with greater flexibility but may expose susceptible soybean and cotton cultivars to non-target herbicide drift. Fr...

  13. KBS-3H - Excavation of two horizontal drifts at the Aespoe Hard Rock Laboratory during year 2004-2005. Work description, summary of results and experience

    Energy Technology Data Exchange (ETDEWEB)

    Baeckblom, Goeran [Conrox AB, Stockholm (Sweden); Lindgren, Erik [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    2005-10-15

    SKB and Posiva Oy in Finland jointly study the possibility to develop a variant of the KBS-3 method for final disposal of spent nuclear fuel. The idea is to make serial deposition of canisters in long horizontal drifts instead of vertical deposition of single canisters in the deposition hole. The studies concerning the horizontal deposition alternative are conducted within the framework of a KBS-3H project, where certain demonstration activities are implemented. A key issue of the running project is to test the ability to excavate the horizontal deposition drifts. The objectives for this work are as follows: To show the feasibility of meeting the geometrical and other requirements; To construct two deposition drifts needed for the later project stages. One drift is needed to demonstrate that heavy load can be transported into the drift. One drift is needed to demonstrate that a plug (bulkhead) can be constructed by low-pH shotcrete; To evaluate the applicability of selected excavation methodologies for realistic repository conditions, and based on the experience in the project define need for technical developments/improvements. To meet the objectives, two deposition drifts were excavated at the Aespoe Hard Rock Laboratory during the period October 2004 to February 2005. One horizontal drift was 15 m in length and one 95 m in length. Both drifts were excavated to the diameter 1.85 m using horizontal push-reaming technology by adapting conventional raise-drilling equipment. The drifts were excavated in good rock conditions where no rock support or grouting was needed for feasible excavation or are needed to operate the drifts. SKB and Posiva have stringent geometrical requirements for the excavated drifts and the conclusions concerning compliance with the requirements are: Length: The project met this target. Two drifts were excavated, 15 m and 95 m respectively in accordance with the initial plan. Diameter: Actually it was not easy to measure the diameters of the

  14. Stringently Defined Otitis Prone Children Demonstrate Deficient Naturally Induced Mucosal Antibody Response toMoraxella catarrhalisProteins.

    Science.gov (United States)

    Ren, Dabin; Murphy, Timothy F; Lafontaine, Eric R; Pichichero, Michael E

    2017-01-01

    Moraxella catarrhalis ( Mcat ) is a prominent mucosal pathogen causing acute otitis media (AOM). We studied Mcat nasopharyngeal (NP) colonization, AOM frequency and mucosal antibody responses to four vaccine candidate Mcat proteins: outer membrane protein (OMP) CD, oligopeptide permease (Opp) A, hemagglutinin (Hag), and Pilin A clade 2 (PilA2) from stringently defined otitis prone (sOP) children, who experience the greatest burden of disease, compared to non-otitis prone (NOP) children. sOP children had higher NP colonization of Mcat (30 vs. 22%, P  = 0.0003) and Mcat -caused AOM rates (49 vs. 24%, P  P  P  = 0.018), Hag (IgG and IgA, both P  P  P  = 0.039) and PilA2 ( P  = 0.0076), and IgA to OMP CD ( P  = 0.010), OppA ( P  = 0.030), and PilA2 ( P  = 0.043) were associated with lower carriage of Mcat in NOP but not sOP children. Higher levels of mucosal IgG to OMP CD ( P  = 0.0070) and Hag ( P  = 0.0003), and IgA to Hag ( P  = 0.0067) at asymptomatic colonization than those at onset of AOM were associated with significantly lower rate of Mcat NP colonization progressing to AOM in NOP compared to sOP children (3 vs. 26%, P  NP colonization and NP colonization progressing to Mcat -caused AOM. Enhancing Mcat antigen-specific mucosal immune responses to levels higher than achieved by natural exposure will be necessary to prevent AOM in sOP children.

  15. Stringent constraints on the dark matter annihilation cross section from subhalo searches with the Fermi Gamma-Ray Space Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Berlin, Asher; Hooper, Dan

    2014-01-01

    The dark matter halo of the Milky Way is predicted to contain a very large number of smaller subhalos. As a result of the dark matter annihilations taking place within such objects, the most nearby and massive subhalos could appear as point-like or spatially extended gamma-ray sources, without observable counterparts at other wavelengths. In this paper, we use the results of the Aquarius simulation to predict the distribution of nearby subhalos, and compare this to the characteristics of the unidentified gamma-ray sources observed by the Fermi Gamma-Ray Space Telescope. Focusing on the brightest high latitude sources, we use this comparison to derive limits on the dark matter annihilation cross section. For dark matter particles lighter than ~200 GeV, the resulting limits are the strongest obtained to date, being modestly more stringent than those derived from observations of dwarf galaxies or the Galactic Center. We also derive independent limits based on the lack of unidentified gamma-ray sources with discernible spatial extension, but these limits are a factor of ~2-10 weaker than those based on point-like subhalos. Lastly, we note that four of the ten brightest high-latitude sources exhibit a similar spectral shape, consistent with 30-60 GeV dark matter particles annihilating to b quarks with an annihilation cross section on the order of sigma v ~ (5-10) x 10^-27 cm^3/s, or 8-10 GeV dark matter particles annihilating to taus with sigma v ~ (2.0-2.5) x 10^-27 cm^3/s.

  16. Unexpected high genetic diversity in small populations suggests maintenance by associative overdominance

    DEFF Research Database (Denmark)

    Fristrup Schou, Mads; Loeschke, Volker; Bechsgaard, Jesper Smærup

    2017-01-01

    The effective population size (Ne) is a central factor in determining maintenance of genetic variation. The neutral theory predicts that loss of variation depends on Ne, with less genetic drift in larger populations. We monitored genetic drift in 42 Drosophila melanogaster populations of different...... fragmented populations. More genetic diversity was retained in areas of low recombination, suggesting that associative overdominance, driven by disfavoured homozygosity of recessive deleterious alleles, is responsible for the maintenance of genetic diversity in smaller populations. Consistent...

  17. In-Drift Precipitates/Salts Analysis

    Energy Technology Data Exchange (ETDEWEB)

    P. Mariner

    2001-01-10

    As directed by a written development plan (CRWMS M&O 1999a), an analysis of the effects of salts and precipitates on the repository chemical environment is to be developed and documented in an Analyses/Model Report (AMR). The purpose of this analysis is to assist Performance Assessment Operations (PAO) and the Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). The purpose of this ICN is to qualify and document qualification of the AMR's technical products. The scope of this document is to develop a model of the processes that govern salt precipitation and dissolution and resulting water composition in the Engineered Barrier System (EBS). This model is developed to serve as a basis for the in-drift geochemical modeling work performed by PAO and is to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. However, the concepts may also apply to some near and far field geochemical processes and can have conceptual application within the unsaturated zone and saturated zone transport modeling efforts. The intended use of the model developed in this report is to estimate, within an appropriate level of confidence, the pH, chloride concentration, and ionic strength of water on the drip shield or other location within the drift during the post-closure period. These estimates are based on evaporative processes that are subject to a broad range of potential environmental conditions and are independent of the presence or absence of backfill. An additional intended use is to estimate the environmental conditions required for complete vaporization of water. The presence and composition of liquid water

  18. Abstraction of Drift-Scale Coupled Processes

    International Nuclear Information System (INIS)

    Francis, N.D.; Sassani, D.

    2000-01-01

    This Analysis/Model Report (AMR) describes an abstraction, for the performance assessment total system model, of the near-field host rock water chemistry and gas-phase composition. It also provides an abstracted process model analysis of potentially important differences in the thermal hydrologic (TH) variables used to describe the performance of a geologic repository obtained from models that include fully coupled reactive transport with thermal hydrology and those that include thermal hydrology alone. Specifically, the motivation of the process-level model comparison between fully coupled thermal-hydrologic-chemical (THC) and thermal-hydrologic-only (TH-only) is to provide the necessary justification as to why the in-drift thermodynamic environment and the near-field host rock percolation flux, the essential TH variables used to describe the performance of a geologic repository, can be obtained using a TH-only model and applied directly into a TSPA abstraction without recourse to a fully coupled reactive transport model. Abstraction as used in the context of this AMR refers to an extraction of essential data or information from the process-level model. The abstraction analysis reproduces and bounds the results of the underlying detailed process-level model. The primary purpose of this AMR is to abstract the results of the fully-coupled, THC model (CRWMS M andO 2000a) for effects on water and gas-phase composition adjacent to the drift wall (in the near-field host rock). It is assumed that drift wall fracture water and gas compositions may enter the emplacement drift before, during, and after the heating period. The heating period includes both the preclosure, in which the repository drifts are ventilated, and the postclosure periods, with backfill and drip shield emplacement at the time of repository closure. Although the preclosure period (50 years) is included in the process models, the postclosure performance assessment starts at the end of this initial period

  19. In-Drift Precipitates/Salts Analysis

    International Nuclear Information System (INIS)

    Mariner, P.

    2001-01-01

    As directed by a written development plan (CRWMS M and O 1999a), an analysis of the effects of salts and precipitates on the repository chemical environment is to be developed and documented in an Analyses/Model Report (AMR). The purpose of this analysis is to assist Performance Assessment Operations (PAO) and the Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). The purpose of this ICN is to qualify and document qualification of the AMR's technical products. The scope of this document is to develop a model of the processes that govern salt precipitation and dissolution and resulting water composition in the Engineered Barrier System (EBS). This model is developed to serve as a basis for the in-drift geochemical modeling work performed by PAO and is to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. However, the concepts may also apply to some near and far field geochemical processes and can have conceptual application within the unsaturated zone and saturated zone transport modeling efforts. The intended use of the model developed in this report is to estimate, within an appropriate level of confidence, the pH, chloride concentration, and ionic strength of water on the drip shield or other location within the drift during the post-closure period. These estimates are based on evaporative processes that are subject to a broad range of potential environmental conditions and are independent of the presence or absence of backfill. An additional intended use is to estimate the environmental conditions required for complete vaporization of water. The presence and composition of liquid water

  20. A novel silicon drift detector with two dimensional drift time measurement

    International Nuclear Information System (INIS)

    Hijzen, E.A.; Schooneveld, E.M.; Van Eijk, C.W.E.; Hollander, R.W.; Sarro, P.M.; Van den Bogaard, A.

    1994-01-01

    Until now silicon drift detectors with two dimensional position resolution made use of drift time measurement in one dimension only. The resolution in the other dimension was obtained by dividing the collecting anode into small pixels. In this paper we present a new type of drift detector that uses drift time measurements for both dimensions. The design consists of concentric quadrilateral closed strips with a small collecting anode in the centre. At first electrons will travel perpendicular to the strips until they reach a diagonal. Then they will proceed along this diagonal until they are collected at the centre. Position resolution in two dimensions can be obtained when both the time the electrons need to reach the diagonal and the time they need to reach the centre are measured. The latter is obtained from the collecting anode, the former from a diagonal strip present at the back side of the detector. Compared to common 2D drift detectors this detector offers the advantage of a small amount of readout electronics. It also has the advantage of having just one small collecting anode with a very low capacitance, resulting in low noise and therefore in a good energy resolution. ((orig.))

  1. Airborne organophosphate pesticides drift in Mediterranean climate: The importance of secondary drift

    Science.gov (United States)

    Zivan, Ohad; Segal-Rosenheimer, Michal; Dubowski, Yael

    2016-02-01

    Pesticide application is a short-term air-pollution episode with near and far field effects due to atmospheric drift. In order to better evaluate resulting air concentrations in nearby communities following pesticide application, measurements of airborne pesticides were conducted at ∼70 m from field edge. This was done following three different application events of the organophosphate pesticide Chlorpyrifos in a persimmon orchard. Complementary information on larger spatial scale was obtained using CALPUFF modeling in which application and meteorological data was used to better evaluate dispersion patterns. Measurements indicated high airborne concentrations during application hours (few μg m-3 for 8 h average), which dropped to tens of ng m-3 in the following days. Measured atmospheric concentrations show that secondary drift (i.e., post-application drift) involves significant loads of pesticides and hence should not be ignored in exposure considerations. Furthermore, CALPUFF modeling revealed the complex dispersion pattern when weak winds prevailed, and showed that during the 24 h after application air concentrations reached levels above the hourly Texas effect screening level (0.1 μg m-3). Interestingly, weak winds on the night after application resulted in a secondary peak in measured and modeled air concentrations. Long exposure time (when secondary drift is considered) and concentrations measured following such common air-assisted orchard application, suggest pesticide drift may have health repercussions that are currently unknown, and emphasize the need for further epidemiological studies.

  2. Eulearian approach to bounce-transit and drift resonance with magnetic drifts in tokamaks

    Science.gov (United States)

    Shaing, Ker Chung; Seol, J.; Chu, M. S.; Sabbagh, S. A.

    2017-10-01

    Bounce-transit and drift resonance can be important to plasma confinement in tokamaks with broken symmetry, and can have implications on the wave-particle resonance. Usually, the resonance is either treated by integrating along the unperturbed orbits or calculated using an action-angle approach. An Eulerian approach has been developed so that momentum conservation property of the Coulomb collision operator can be taken into account. The parallel flows appear in the thermodynamic forces in the Eulerian approach. However, in the existing theory, only E × B drift is kept; the magnetic drifts are neglected by adopting the large aspect ratio assumption. Here, E is the electric field, and B is the magnetic field. The importance of the magnetic drifts in finite aspect ratio tokamaks is demonstrated in. Here, the Eulerian approach is extended to include the magnetic drifts to calculate neoclassical toroidal plasma viscosity in finite aspect ratio tokamaks. The relation to the nonlinear plasma viscosity in the plateau regime will also be discussed. This work was supported by Taiwan Ministry of Science and Technology under Grant No. 100-2112-M-006-004-MY3, and Republic of Korea MSIP (Ministry of Science, ICT and Future Planning) under KSTAR program.

  3. Task 1.5 Genomic Shift and Drift Trends of Emerging Pathogens

    Energy Technology Data Exchange (ETDEWEB)

    Borucki, M

    2010-01-05

    The Lawrence Livermore National Laboratory (LLNL) Bioinformatics group has recently taken on a role in DTRA's Transformation Medical Technologies Initiative (TMTI). The high-level goal of TMTI is to accelerate the development of broad-spectrum countermeasures. To achieve those goals, TMTI has a near term need to conduct analyses of genomic shift and drift trends of emerging pathogens, with a focused eye on select agent pathogens, as well as antibiotic and virulence markers. Most emerging human pathogens are zoonotic viruses with a genome composed of RNA. The high mutation rate of the replication enzymes of RNA viruses contributes to sequence drift and provides one mechanism for these viruses to adapt to diverse hosts (interspecies transmission events) and cause new human and zoonotic diseases. Additionally, new viral pathogens frequently emerge due to genetic shift (recombination and segment reassortment) which allows for dramatic genotypic and phenotypic changes to occur rapidly. Bacterial pathogens also evolve via genetic drift and shift, although sequence drift generally occurs at a much slower rate for bacteria as compared to RNA viruses. However, genetic shift such as lateral gene transfer and inter- and intragenomic recombination enables bacteria to rapidly acquire new mechanisms of survival and antibiotic resistance. New technologies such as rapid whole genome sequencing of bacterial genomes, ultra-deep sequencing of RNA virus populations, metagenomic studies of environments rich in antibiotic resistance genes, and the use of microarrays for the detection and characterization of emerging pathogens provide mechanisms to address the challenges posed by the rapid emergence of pathogens. Bioinformatic algorithms that enable efficient analysis of the massive amounts of data generated by these technologies as well computational modeling of protein structures and evolutionary processes need to be developed to allow the technology to fulfill its potential.

  4. Ashkenazi Jewish genetic disorders.

    Science.gov (United States)

    Charrow, Joel

    2004-01-01

    The frequency of several genes responsible for 'single-gene' disorders and disease predispositions is higher among Ashkenazi Jews than among Sephardi Jews and non-Jews. The disparity is most likely the result of founder effect and genetic drift, rather than heterozygote advantage. The more common Mendelian Ashkenazi Jewish genetic disorders are summarized, and examples of variable expressivity and penetrance, inconsistent genotype-phenotype correlation, and potential modifiers are presented. The importance of genetic counseling in both the pre- and post-test phases of population screening is emphasized.

  5. Development of an equipment diagnostic system that evaluates sensor drift

    International Nuclear Information System (INIS)

    Kanada, Masaki; Arita, Setsuo; Tada, Nobuo; Yokota, Katsuo

    2011-01-01

    The importance of condition monitoring technology for equipment has increased with the introduction of condition-based maintenance in nuclear power plants. We are developing a diagnostic system using process signals for plant equipment, such as pumps and motors. It is important to enable the diagnostic system to distinguish sensor drift and equipment failure. We have developed a sensor drift diagnostic method that combines some highly correlative sensor signals by using the MT (Mahalanobis-Taguchi) method. Furthermore, we have developed an equipment failure diagnostic method that measures the Mahalanobis distance from the normal state of equipment by the MT method. These methods can respectively detect sensor drift and equipment failure, but there are the following problems. In the sensor drift diagnosis, there is a possibility of misjudging the sensor drift when the equipment failure occurs and the process signal changes because the behavior of the process signal is the same as that of the sensor drift. Oppositely, in the equipment failure diagnosis, there is a possibility of misjudging the equipment failure when the sensor drift occurs because the sensor drift influences the change of process signal. To solve these problems, we propose a diagnostic method combining the sensor drift diagnosis and the equipment failure diagnosis by the MT method. Firstly, the sensor drift values are estimated by the sensor drift diagnosis, and the sensor drift is removed from the process signal. It is necessary to judge the validity of the estimated sensor drift values before removing the sensor drift from the process signal. We developed a method for judging the validity of the estimated sensor drift values by using the drift distribution based on the sensor calibration data. And then, the equipment failure is diagnosed by using the process signals after removal of the sensor drifts. To verify the developed diagnostic system, several sets of simulation data based on abnormal cases

  6. Demersally drifting invertebrates from Kongsfjorden, Svalbård (Arctic Ocean)-a comparison of catches from drift-pump and drift-nets

    Science.gov (United States)

    Dahms, Hans-Uwe; Joo, Hyoung-Min; Lee, Jae Hyung; Yun, Mi Sun; Ahn, So Hyun; Lee, Sang Heon

    2015-12-01

    Demersally drifting organisms were collected at Ny Ålesund (Svalbård-Arctic Ocean) to study the taxon composition and relative abundances in the Arctic summer. Catch potentials of two collection devices for demersal drift were compared. A lowvolume submersible drift-pump and a drift-net unit were employed for the collection of demersally drifting biota, particularly for shallow aquatic habitats. With the exception of Appendicularia, Chaetognatha, Coelenterata, and Ctenophora, which were damaged at times, the pump catches were in good condition and sufficient for identification and quantification of less mobile fauna. A comparison of the two devices revealed that the drift-pump collected more specimens than the drift-net. However, the drift-net may have caused an underestimation of the abundances of invertebrates. No differences in identified taxon number and indices of richness, evenness and diversity were found. However, the proportion of invertebrate animals in the two devices was different for the three groups: zooplankton, macrofauna and meiofauna. At Svalbård, zooplankton, larvae of macrofauna, and meiofauna were successfully collected by the two collecting devices. However, the catchibility of the two devices in collecting various invertebrate taxa was different and, therefore, a sound `Device Effect' was revealed.

  7. Drift Tube Linac Conditioning of Tank1

    CERN Document Server

    Shafqat, N; Toor, W A

    2014-01-01

    Tank1 of the Drift Tube Linac (DTL) of the Linac4 has been conditioned at the Linac4 tunnel. The tank was tuned for resonance at 352.2 MHz, and stable operation has been achieved with 725 µs long RF pulses at a repetition rate of 1 Hz. The maximum RF level that has been reached is 810 kW with a pulse width of 600 µs. Since this was the first RF structure exclusively conditioned in the Linac4 tunnel with the operation and control software of Linac4, some related issues and limitations had to be taken into account.

  8. Drift chambers in BM@N Experiment

    Directory of Open Access Journals (Sweden)

    Fedorišin Ján

    2017-01-01

    In first step, the radius vs drift time calibration curve is estimated and applied to calculate DCH hit closest approach coordinates. These coordinates are used to construct hits in each DCH under the assumption of track linearity. Hits in both the DCHs are subsequently aligned and fitted to produce global linear track candidates. Eventually the hit and track reconstruction is optimized by the autocalibration method. The coordinate resolutions are estimated from Gaussian fits of the DCH hit residual spectra for different DCH planes. Furthermore, the deuteron beam momentum value is reconstructed in order to check reliability of the employed track reconstruction algorithm.

  9. Cathode Readout with Stripped Resistive Drift Tubes

    International Nuclear Information System (INIS)

    Bychkov, V.N.; Kekelidze, G.D.; Novikov, E.A.; Peshekhonov, V.D.; Shafranov, M.D.; Zhil'tsov, V.E.

    1994-01-01

    A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with carbon layer of resistivity 0.5, 30 and 70 k Ohm/sq. The gas mixture used was Ar/CH 4 . Both the anode wire and cathode signals were detected in order to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented. 7 refs., 11 figs., 1 tab

  10. Strange Attractors in Drift Wave Turbulence

    International Nuclear Information System (INIS)

    Lewandowski, Jerome L.V.

    2003-01-01

    There are growing experimental, numerical and theoretical evidences that the anomalous transport observed in tokamaks and stellarators is caused by slow, drift-type modes (such as trapped electron modes and ion-temperature gradient-driven modes). Although typical collision frequencies in hot, magnetized fusion plasmas can be quite low in absolute values, collisional effects are nevertheless important since they act as dissipative sinks. As it is well known, dissipative systems with many (strictly speaking more than two) degrees of freedom are often chaotic and may evolve towards a so-called attractor

  11. MAGSAT anomaly map and continental drift

    Science.gov (United States)

    Lemouel, J. L. (Principal Investigator); Galdeano, A.; Ducruix, J.

    1981-01-01

    Anomaly maps of high quality are needed to display unambiguously the so called long wave length anomalies. The anomalies were analyzed in terms of continental drift and the nature of their sources is discussed. The map presented confirms the thinness of the oceanic magnetized layer. Continental magnetic anomalies are characterized by elongated structures generally of east-west trend. Paleomagnetic reconstruction shows that the anomalies found in India, Australia, and Antarctic exhibit a fair consistency with the African anomalies. It is also shown that anomalies are locked under the continents and have a fixed geometry.

  12. Analysis of digisonde drift measurements quality

    Czech Academy of Sciences Publication Activity Database

    Kouba, Daniel; Koucká Knížová, Petra

    90-91, December (2012), s. 212-221 ISSN 1364-6826. [IAGA/ICMA/CAWSES-II TG4 Workshop on Vertical Coupling in the Atmosphere-Ionosphere System /4./. Prague, 14.02.2011-18.02.2011] R&D Projects: GA AV ČR KJB300420904; GA AV ČR IAA300420704 Institutional support: RVO:68378289 Keywords : Ionosphere * Plasma drifts * Skymap * Digisonde Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.417, year: 2012 http://www.sciencedirect.com/science/article/pii/S1364682612001290

  13. Autocalibration of high precision drift tubes

    International Nuclear Information System (INIS)

    Bacci, C.; Bini, C.; Ciapetti, G.; De Zorzi, G.; Gauzzi, P.; Lacava, F.; Nisati, A.; Pontecorvo, L.; Rosati, S.; Veneziano, S.; Cambiaghi, M.; Casellotti, G.; Conta, C.; Fraternali, M.; Lanza, A.; Livan, M.; Polesello, G.; Rimoldi, A.; Vercesi, V.

    1997-01-01

    We present the results on MDT (monitored drift tubes) autocalibration studies obtained from the analysis of the data collected in Summer 1995 on the H8B Muon Test Beam. In particular we studied the possibility of autocalibration of the MDT using four or three layers of tubes, and we compared the calibration obtained using a precise external tracker with the output of the autocalibration procedure. Results show the feasibility of autocalibration with four and three tubes and the good accuracy of the autocalibration procedure. (orig.)

  14. Effects of Drifting Macroalgae in Eelgrass Ecosystems

    DEFF Research Database (Denmark)

    Canal Vergés, Paula; Valdemarsen, Thomas Bruun; Kristensen, Erik

    2010-01-01

    –10 mg suspended particulate matter (SPM) L-1 to 30–50 mg SPM L 1 for Ceramium sp., Ulva lactuca and Chaetomorpha linum, respectively, while the more rigid Gracilaria sp. and Fucus vesiculosus lead to much higher turbidity (50–180 mg SPM L−1). Preliminary results from Odense Fjord (Denmark) confirm...... and physical damage on eelgrass can occur when macroalgae are drifting as bedload. The ballistic effect of moving macroalgae on surface sediment was tested in the field as well as in a series of annular flume experiments, where simultaneous measurements of macroalgae transport and turbidity were measured...

  15. The Mark II Vertex Drift Chamber

    International Nuclear Information System (INIS)

    Alexander, J.P.; Baggs, R.; Fujino, D.

    1989-03-01

    We have completed constructing and begun operating the Mark II Drift Chamber Vertex Detector. The chamber, based on a modified jet cell design, achieves 30 μm spatial resolution and 2 gas mixtures. Special emphasis has been placed on controlling systematic errors including the use of novel construction techniques which permit accurate wire placement. Chamber performance has been studied with cosmic ray tracks collected with the chamber located both inside and outside the Mark II. Results on spatial resolution, average pulse shape, and some properties of CO 2 mixtures are presented. 10 refs., 12 figs., 1 tab

  16. Crowdsourcing and annotating NER for Twitter #drift

    DEFF Research Database (Denmark)

    Fromreide, Hege; Hovy, Dirk; Søgaard, Anders

    2014-01-01

    We present two new NER datasets for Twitter; a manually annotated set of 1,467 tweets (kappa=0.942) and a set of 2,975 expert-corrected, crowdsourced NER annotated tweets from the dataset described in Finin et al. (2010). In our experiments with these datasets, we observe two important points: (a......) language drift on Twitter is significant, and while off-the-shelf systems have been reported to perform well on in-sample data, they often perform poorly on new samples of tweets, (b) state-of-the-art performance across various datasets can beobtained from crowdsourced annotations, making it more feasible...

  17. EMPLACEMENT DRIFT ISOLATION DOOR CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    N.T. Raczka

    1998-09-17

    The purpose of this analysis is to review and refine key design concepts related to the control system presently under consideration for remotely operating the emplacement drift isolation doors at the potential subsurface nuclear waste repository at Yucca Mountain. This analysis will discuss the key design concepts of the control system that may be utilized for remotely monitoring, opening, and closing the emplacement drift isolation doors. The scope and primary objectives of this analysis are to: (1) Discuss the purpose and function of the isolation doors (Presented in Section 7.1). (2) Review the construction of the isolation door and other physical characteristics of the doors that the control system will interface with (Presented in Section 7.2). (3) Discuss monitoring and controlling the operation of the isolation doors with a digital control system (either a Programmable Logic Controller (PLC) system or a Distributed Control System (DCS)) (Presented in Section 7.3). (4) Discuss how all isolation doors can be monitored and controlled from a subsurface central control center (Presented in Section 7.4). This analysis will focus on the development of input/output (I/O) counts including the types of I/O, redundancy and fault tolerance considerations, and processor requirements for the isolation door control system. Attention will be placed on operability, maintainability, and reliability issues for the system operating in the subsurface environment with exposure to high temperatures and radiation.

  18. EMPLACEMENT DRIFT ISOLATION DOOR CONTROL SYSTEM

    International Nuclear Information System (INIS)

    N.T. Raczka

    1998-01-01

    The purpose of this analysis is to review and refine key design concepts related to the control system presently under consideration for remotely operating the emplacement drift isolation doors at the potential subsurface nuclear waste repository at Yucca Mountain. This analysis will discuss the key design concepts of the control system that may be utilized for remotely monitoring, opening, and closing the emplacement drift isolation doors. The scope and primary objectives of this analysis are to: (1) Discuss the purpose and function of the isolation doors (Presented in Section 7.1). (2) Review the construction of the isolation door and other physical characteristics of the doors that the control system will interface with (Presented in Section 7.2). (3) Discuss monitoring and controlling the operation of the isolation doors with a digital control system (either a Programmable Logic Controller (PLC) system or a Distributed Control System (DCS)) (Presented in Section 7.3). (4) Discuss how all isolation doors can be monitored and controlled from a subsurface central control center (Presented in Section 7.4). This analysis will focus on the development of input/output (I/O) counts including the types of I/O, redundancy and fault tolerance considerations, and processor requirements for the isolation door control system. Attention will be placed on operability, maintainability, and reliability issues for the system operating in the subsurface environment with exposure to high temperatures and radiation

  19. PWCs and drift chambers at ISABELLE

    International Nuclear Information System (INIS)

    Okuno, H.; Teramoto, Y.; Wheeler, C.D.

    1978-01-01

    Rate effects in proportional chambers and drift chambers are addressed first. The widely used high-gas-gain chambers would have impaired performance at ISABELLE data rates. Improvement can be expected with lower gas gain, and this possibility is investigated with respect to position and time resolution. Results on chamber lifetime are summarized; space-charge effects, gain saturation, and radiation hardness of electronics are considered. The resolution of drift chambers is discussed in some detail; time resolution, double pulse resolution, and momentum resolution and multiple scattering are included. The expected high multiplicity of tracks from a single event, the high event rates, and the requirement for low gas gain necessitate revision of the methods for measuring the second coordinate. Known methods of two-dimensional point localization are summarized according to spatial accuracy, electronics requirements, and multihit capability. Delay lines, charge division, and cathode strips are considered. Particle identification by means of measurement of the relativistic rise of energy loss by conventional and unconventional means was investigated. 32 references, 3 figures, 4 tables

  20. Metabolic drift in the aging brain.

    Science.gov (United States)

    Ivanisevic, Julijana; Stauch, Kelly L; Petrascheck, Michael; Benton, H Paul; Epstein, Adrian A; Fang, Mingliang; Gorantla, Santhi; Tran, Minerva; Hoang, Linh; Kurczy, Michael E; Boska, Michael D; Gendelman, Howard E; Fox, Howard S; Siuzdak, Gary

    2016-05-01

    Brain function is highly dependent upon controlled energy metabolism whose loss heralds cognitive impairments. This is particularly notable in the aged individuals and in age-related neurodegenerative diseases. However, how metabolic homeostasis is disrupted in the aging brain is still poorly understood. Here we performed global, metabolomic and proteomic analyses across different anatomical regions of mouse brain at different stages of its adult lifespan. Interestingly, while severe proteomic imbalance was absent, global-untargeted metabolomics revealed an energymetabolic drift or significant imbalance in core metabolite levels in aged mouse brains. Metabolic imbalance was characterized by compromised cellular energy status (NAD decline, increased AMP/ATP, purine/pyrimidine accumulation) and significantly altered oxidative phosphorylation and nucleotide biosynthesis and degradation. The central energy metabolic drift suggests a failure of the cellular machinery to restore metabostasis (metabolite homeostasis) in the aged brain and therefore an inability to respond properly to external stimuli, likely driving the alterations in signaling activity and thus in neuronal function and communication.

  1. In-Drift Precipitates/Salts Model

    International Nuclear Information System (INIS)

    P. Mariner

    2004-01-01

    This report documents the development and validation of the in-drift precipitates/salts (IDPS) model. The IDPS model is a geochemical model designed to predict the postclosure effects of evaporation and deliquescence on the chemical composition of water within the Engineered Barrier System (EBS) in support of the Total System Performance Assessment for the License Application (TSPA-LA). Application of the model in support of TSPA-LA is documented in ''Engineered Barrier System: Physical and Chemical Environment Model'' (BSC 2004 [DIRS 169860]). Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration (BSC 2004 [DIRS 171156]) is the technical work plan (TWP) for this report. It called for a revision of the previous version of the report (BSC 2004 [DIRS 167734]) to achieve greater transparency, readability, data traceability, and report integration. The intended use of the IDPS model is to estimate and tabulate, within an appropriate level of confidence, the effects of evaporation, deliquescence, and potential environmental conditions on the pH, ionic strength, and chemical compositions of water and minerals on the drip shield or other location within the drift during the postclosure period. Specifically, the intended use is as follows: (1) To estimate, within an appropriate level of confidence, the effects of evaporation and deliquescence on the presence and composition of water occurring within the repository during the postclosure period (i.e., effects on pH, ionic strength, deliquescence relative humidity, total concentrations of dissolved components in the system Na-K-H-Mg-Ca-Al-Cl-F-NO 3 -SO 4 -Br-CO 3 -SiO 2 -CO 2 -O 2 -H 2 O, and concentrations of the following aqueous species that potentially affect acid neutralizing capacity: HCO 3 - , CO 3 2- , OH - , H + , HSO 4 - , Ca 2+ , Mg 2+ , CaHCO 3 + , MgHCO 3 + , HSiO 3 - , and MgOH + ); (2) To estimate, within an appropriate level of confidence, mineral

  2. In-Drift Precipitates/Salts Model

    Energy Technology Data Exchange (ETDEWEB)

    P. Mariner

    2004-11-09

    This report documents the development and validation of the in-drift precipitates/salts (IDPS) model. The IDPS model is a geochemical model designed to predict the postclosure effects of evaporation and deliquescence on the chemical composition of water within the Engineered Barrier System (EBS) in support of the Total System Performance Assessment for the License Application (TSPA-LA). Application of the model in support of TSPA-LA is documented in ''Engineered Barrier System: Physical and Chemical Environment Model'' (BSC 2004 [DIRS 169860]). Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration (BSC 2004 [DIRS 171156]) is the technical work plan (TWP) for this report. It called for a revision of the previous version of the report (BSC 2004 [DIRS 167734]) to achieve greater transparency, readability, data traceability, and report integration. The intended use of the IDPS model is to estimate and tabulate, within an appropriate level of confidence, the effects of evaporation, deliquescence, and potential environmental conditions on the pH, ionic strength, and chemical compositions of water and minerals on the drip shield or other location within the drift during the postclosure period. Specifically, the intended use is as follows: (1) To estimate, within an appropriate level of confidence, the effects of evaporation and deliquescence on the presence and composition of water occurring within the repository during the postclosure period (i.e., effects on pH, ionic strength, deliquescence relative humidity, total concentrations of dissolved components in the system Na-K-H-Mg-Ca-Al-Cl-F-NO{sub 3}-SO{sub 4}-Br-CO{sub 3}-SiO{sub 2}-CO{sub 2}-O{sub 2}-H{sub 2}O, and concentrations of the following aqueous species that potentially affect acid neutralizing capacity: HCO{sub 3}{sup -}, CO{sub 3}{sup 2-}, OH{sup -}, H{sup +}, HSO{sub 4}{sup -}, Ca{sup 2+}, Mg{sup 2+}, CaHCO{sub 3}{sup +}, MgHCO{sub 3

  3. Proportional drift tubes for large area muon detectors

    Science.gov (United States)

    Cho, C.; Higashi, S.; Hiraoka, N.; Maruyama, A.; Okusawa, T.; Sato, T.; Suwada, T.; Takahashi, T.; Umeda, H.

    1985-01-01

    A proportional drift chamber which consists of eight rectangular drift tubes with cross section of 10 cm x 5 cm, a sense wire of 100 micron phi gold-plated tungsten wire and the length of 6 m, was tested using cosmic ray muons. Spatial resolution (rms) is between 0.5 and 1 mm over drift space of 50 mm, depending on incident angle and distance from sense wire.

  4. Analysis of drift correction in different simulated weighing schemes

    Science.gov (United States)

    Beatrici, A.; Rebelo, A.; Quintão, D.; Cacais, F. L.; Loayza, V. M.

    2015-10-01

    In the calibration of high accuracy mass standards some weighing schemes are used to reduce or eliminate the zero drift effects in mass comparators. There are different sources for the drift and different methods for its treatment. By using numerical methods, drift functions were simulated and a random term was included in each function. The comparison between the results obtained from ABABAB and ABBA weighing series was carried out. The results show a better efficacy of ABABAB method for drift with smooth variation and small randomness.

  5. A new silicon drift detector with reduced lateral diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Castoldi, A. [Milan Univ. (Italy). Dipt. di Fisica; Rehak, P. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Holl, P. [MPI Halbleiterlabor, Paul-Gerhardt-Allee 42, D-81245 Muenchen (Germany)

    1996-08-01

    We present a method to reduce the effect of diffusion in the direction transverse to the drift in silicon drift detectors. This is achieved by creating regions of deep p-implant parallel to the drift direction that act as rigid guidelines during the drift of the charge cloud generated by a radiation interaction. The influence of the deep implanted acceptors on the lateral confining field is discussed. A prototype has been designed, fabricated and tested. First experimental results are reported which demonstrate the achieved reduction of the lateral width of the electron cloud with respect to free broadening. (orig.).

  6. 3lambda/4 post coupler for drift-tube linacs

    Energy Technology Data Exchange (ETDEWEB)

    Billen, J.H.; Garcia, J.A.; Potter, J.M.; Spalek, G.

    1985-01-01

    New permanent magnets for quadrupole focusing make possible smaller drift tubes in drift-tube linacs (DTLs), resulting in higher shunt impedance. However, ordinary post couplers cannot stabilize a DTL whose drift-tube-to-wall spacing exceeds one-quarter wavelength (lambda/4) by more than a few per cent for the accelerating mode frequency. We have built and tested post couplers that operate in the 3lambda/4 mode. These 3lambda/4 post couplers, when substituted for lambda/4 couplers, had similar stabilization properties. In addition, the coupling between post and drift tube, and the post's resonant frequency can be independently adjusted. 5 refs., 5 figs.

  7. Silicon Drift Detectors with the Drift Field Induced by PureB-Coated Trenches

    Directory of Open Access Journals (Sweden)

    Tihomir Knežević

    2016-10-01

    Full Text Available Junction formation in deep trenches is proposed as a new means of creating a built-in drift field in silicon drift detectors (SDDs. The potential performance of this trenched drift detector (TDD was investigated analytically and through simulations, and compared to simulations of conventional bulk-silicon drift detector (BSDD configurations. Although the device was not experimentally realized, the manufacturability of the TDDs is estimated to be good on the basis of previously demonstrated photodiodes and detectors fabricated in PureB technology. The pure boron deposition of this technology allows good trench coverage and is known to provide nm-shallow low-noise p+n diodes that can be used as radiation-hard light-entrance windows. With this type of diode, the TDDs would be suitable for X-ray radiation detection down to 100 eV and up to tens of keV energy levels. In the TDD, the drift region is formed by varying the geometry and position of the trenches while the reverse biasing of all diodes is kept at the same constant voltage. For a given wafer doping, the drift field is lower for the TDD than for a BSDD and it demands a much higher voltage between the anode and cathode, but also has several advantages: it eliminates the possibility of punch-through and no current flows from the inner to outer perimeter of the cathode because a voltage divider is not needed to set the drift field. In addition, the loss of sensitive area at the outer perimeter of the cathode is much smaller. For example, the simulations predict that an optimized TDD geometry with an active-region radius of 3100 µm could have a drift field of 370 V/cm and a photo-sensitive radius that is 500-µm larger than that of a comparable BSDD structure. The PureB diodes on the front and back of the TDD are continuous, which means low dark currents and high stability with respect to leakage currents that otherwise could be caused by radiation damage. The dark current of the 3100-µm TDD

  8. Tabulated In-Drift Geometric and Thermal Properties Used In Drift-Scale Models for TSPA-SR

    International Nuclear Information System (INIS)

    N.D. Francis

    2000-01-01

    The objective of this calculation is to provide in-drift physical properties required by the drift-scale models (both two- and three-dimensional) used in total system performance assessments (TSPA). The physical properties include waste package geometry, waste package thermal properties, emplacement drift geometry including backfill and invert geometry and properties (both thermal and hydrologic), drip shield geometry and thermal properties, all tabulated in a single source

  9. Overcoming Challenges in Engineering the Genetic Code.

    Science.gov (United States)

    Lajoie, M J; Söll, D; Church, G M

    2016-02-27

    Withstanding 3.5 billion years of genetic drift, the canonical genetic code remains such a fundamental foundation for the complexity of life that it is highly conserved across all three phylogenetic domains. Genome engineering technologies are now making it possible to rationally change the genetic code, offering resistance to viruses, genetic isolation from horizontal gene transfer, and prevention of environmental escape by genetically modified organisms. We discuss the biochemical, genetic, and technological challenges that must be overcome in order to engineer the genetic code. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. The paradox of forest fragmentation genetics

    Science.gov (United States)

    Andrea T. Kramer; Jennifer L. Ison; Mary V. Ashley; Henry F. Howe

    2008-01-01

    Theory predicts widespread loss of genetic diversity from drift and inbreeding in trees subjected to habitat fragmentation, yet empirical support of this theory is scarce. We argue that population genetics theory may be misapplied in light of ecological realities that, when recognized, require scrutiny of underlying evolutionary assumptions. One ecological reality is...

  11. ONLINE RESOURCES Assessment of Genetic Diversity and ...

    Indian Academy of Sciences (India)

    Sony

    including null alleles, mutation, nature of the plant, selection process, small population size and heterozygote deficiency. The most important factor is sampling effect called genetic drift which causes a random change in genotypic frequencies. Evaluation of genetic variation and cluster analysis. The results obtained from ...

  12. Electro-mechanics of drift tube wires

    International Nuclear Information System (INIS)

    Milburn, R.H.

    1997-01-01

    The position and stability of the sense wires in very long drift tubes are affected by both gravitational and electrostatic forces, as well as by the wire tension. For a tube to be used as an element of a high-resolution detector all these forces and their effects must be understood in appropriately precise detail. In addition, the quality control procedures applied during manufacture and detector installation must be adequate to ensure that the internal wire positions remain within tolerances. It may be instructive to practitioners to review the simple theory of a taut wire in the presence of anisotropic gravitational and electrostatic fields to illustrate the conditions for stability, the equilibrium wire displacement from straightness, and the effect of the fields on the mechanical vibration frequencies. These last may be used to monitor the wire configuration externally. A number of practical formulae result and these are applied to illustrative examples. (orig.)

  13. Variable-energy drift-tube linacs

    International Nuclear Information System (INIS)

    Swenson, D.A.; Boyd, T.J.; Potter, J.M.; Stovall, J.E.

    1981-01-01

    Practical applications of ion linacs are more viable now than ever before because of the recent development of the radio-frequency quadrupole accelerating structure, as well as other technological advances developed under the Pion Generator for Medical Irradiations program. This report describes a practical technique for varying the energy of drift-tube linacs and thus further broadening the possibilities for linac applications. This technique involves using the post couplers (normally used to flatten and stabilize the electric fields) to create a step in the fields, thus terminating the acceleration process. In the examples given for a 70-MeV accelerator design, when using this technique the energy is continuously variable down to 20 MeV, while maintaining a small energy spread

  14. Nonlinear evolution of drift cyclotron modes

    International Nuclear Information System (INIS)

    Aamodt, R.E.; Cohen, B.I.; Lee, Y.C.; Liu, C.S.; Nicholson, D.R.; Rosenbluth, M.N.

    1981-01-01

    The space-time evolution of the drift-cyclotron instability as influenced by the nonlinear shift in the ion-cyclotron frequency is studied analytically, numerically, and by computer simulation. The analysis is specialized to the case of a single coherent wave with frequency near both a cyclotron harmonic and the ion diamagnetic frequency. Such an analysis is motivated by observations of large-amplitude ion-cyclotron waves in the 2XIIB mirror experiment, which were highly monochromatic and often exhibited these frequency characteristics. A nonlinear dispersion relation describing saturation of the instability is derived by means of a self-consistent analytical solution of the Vlasov--Poisson equations to third order in the wave amplitude. Solitary wave and self-similar solutions are obtained that describe nonlinear wave propagation. Numerical solution of a nonlinear evolution equation and particle simulation confirm the analysis

  15. Multilevel Drift-Implicit Tau-Leap

    KAUST Repository

    Ben Hammouda, Chiheb

    2016-01-06

    The dynamics of biochemical reactive systems with small copy numbers of one or more reactant molecules is dominated by stochastic effects. For those systems, discrete state-space and stochastic simulation approaches were proved to be more relevant than continuous state-space and deterministic ones. In systems characterized by having simultaneously fast and slowtimescales, the existing discrete space-state stochastic path simulation methods such as the stochastic simulation algorithm (SSA) and the explicit tauleap method can be very slow. Implicit approximations were developed in the literature to improve numerical stability and provide efficient simulation algorithms for those systems. In this work, we propose an efficient Multilevel Monte Carlo method in the spirit of the work by Anderson and Higham (2012) that uses drift-implicit tau-leap approximations at levels where the explicit tauleap method is not applicable due to numerical stability issues. We present numerical examples that illustrate the performance of the proposed method.

  16. Physics issues of compact drift optimized stellarators

    International Nuclear Information System (INIS)

    Spong, D.A.; Hirshman, S.; Berry, L.A.

    2001-01-01

    Physics issues are discussed for compact stellarator configurations which achieve good confinement by the fact that the magnetic field modulus, vertical bar B vertical bar, in magnetic coordinates is dominated by poloidally symmetric components. Two distinct configuration types are considered: (1) those which achieve their drift optimization and rotational transform at low β and low bootstrap current by appropriate plasma shaping; and (2) those which have a greater reliance on plasma β and bootstrap currents for supplying the transform and obtaining quasi poloidal symmetry. Stability analysis of the latter group of devices against ballooning, kink and vertical displacement modes has indicated that stable 's on the order of 15% are possible. The first class of devices is being considered for a low β near-term experiment that could explore some of the confinement features of the high beta configurations. (author)

  17. Spectroscopic measurements with a silicon drift detector having a continuous implanted drift cathode-voltage divider

    CERN Document Server

    Bonvicini, V; D'Acunto, L; Franck, D; Gregorio, A; Pihet, P; Rashevsky, A; Vacchi, A; Vinogradov, L I; Zampa, N

    2000-01-01

    A silicon drift detector (SDD) prototype where the drift electrode also plays the role of a high-voltage divider has been realised and characterised for spectroscopic applications at near-room temperatures. Among the advantages of this design, is the absence of metal on the sensitive surface which makes this detector interesting for soft X-rays. The detector prototype has a large sensitive area (2x130 mm sup 2) and the charge is collected by two anodes (butterfly-like detector). The energy resolution of a such a detector has been investigated at near-room temperatures using a commercial, hybrid, low-noise charge-sensitive preamplifier. The results obtained for the X-ray lines from sup 5 sup 5 Fe and sup 2 sup 4 sup 1 Am are presented.

  18. Dual Regulation of Bacillus subtilis kinB Gene Encoding a Sporulation Trigger by SinR through Transcription Repression and Positive Stringent Transcription Control

    Directory of Open Access Journals (Sweden)

    Yasutaro Fujita

    2017-12-01

    Full Text Available It is known that transcription of kinB encoding a trigger for Bacillus subtilis sporulation is under repression by SinR, a master repressor of biofilm formation, and under positive stringent transcription control depending on the adenine species at the transcription initiation nucleotide (nt. Deletion and base substitution analyses of the kinB promoter (PkinB region using lacZ fusions indicated that either a 5-nt deletion (Δ5, nt -61/-57, +1 is the transcription initiation nt or the substitution of G at nt -45 with A (G-45A relieved kinB repression. Thus, we found a pair of SinR-binding consensus sequences (GTTCTYT; Y is T or C in an inverted orientation (SinR-1 between nt -57/-42, which is most likely a SinR-binding site for kinB repression. This relief from SinR repression likely requires SinI, an antagonist of SinR. Surprisingly, we found that SinR is essential for positive stringent transcription control of PkinB. Electrophoretic mobility shift assay (EMSA analysis indicated that SinR bound not only to SinR-1 but also to SinR-2 (nt -29/-8 consisting of another pair of SinR consensus sequences in a tandem repeat arrangement; the two sequences partially overlap the ‘-35’ and ‘-10’ regions of PkinB. Introduction of base substitutions (T-27C C-26T in the upstream consensus sequence of SinR-2 affected positive stringent transcription control of PkinB, suggesting that SinR binding to SinR-2 likely causes this positive control. EMSA also implied that RNA polymerase and SinR are possibly bound together to SinR-2 to form a transcription initiation complex for kinB transcription. Thus, it was suggested in this work that derepression of kinB from SinR repression by SinI induced by Spo0A∼P and occurrence of SinR-dependent positive stringent transcription control of kinB might induce effective sporulation cooperatively, implying an intimate interplay by stringent response, sporulation, and biofilm formation.

  19. The construction technique of the high granularity and high transparency drift chamber of MEG II

    Science.gov (United States)

    Chiarello, G.; Chiri, C.; Corvaglia, A.; Grancagnolo, F.; Miccoli, A.; Panareo, M.; Pinto, C.; Spedicato, M.; Tassielli, G. F.

    2017-07-01

    The MEG experiment searches for the charged lepton flavor violating decay, μ +→ e+γ. MEG has already determined the world best upper limit on the branching ratio BRfeed-through technique as wire anchoring system could hardly be implemented and therefore it was necessary to develop new wiring strategies. The number of wires and the stringent requirements on the precision of their position and on the uniformity of the wire mechanical tension impose the use of an automatic system to operate the wiring procedures. This wiring robot, designed and built at the INFN Lecce and University of Salento laboratories, consists of: ṡ a semiautomatic wiring machine with a high precision on wire mechanical tensioning (better than 0.5 g) and on wire positioning (20 μ m) for simultaneous wiring of multiwire layers; ṡ a contact-less infrared laser soldering tool; ṡ an automatic handling system for storing and transporting the multi-wire layers. The drift chamber is currently under construction at INFN and should be completed by the end of summer 2017 to be then delivered to PSI for commissioning.

  20. A chopper-stabilized long pulse integrator with low drift

    International Nuclear Information System (INIS)

    Wei Yongqing; Xie Jikang; Wan Baonian; Shen Biao

    2006-01-01

    A chopper-stabilized integrator for tokamak with a digital signal processing unit to dynamically suppress the primary drift factors of analog integrator, has been designed. Long pulse integrations with low drift have been obtained with this apparatus in experiments. (authors)

  1. Solitary drift waves in the presence of magnetic shear

    International Nuclear Information System (INIS)

    Meiss, J.D.; Horton, W.

    1982-07-01

    The two-component fluid equations describing electron drift and ion acoustic waves in a nonuniform magnetized plasma are shown to possess nonlinear two-dimensional solitary wave solutions. In the presence of magnetic shear, radiative shear damping is exponentially small in L/sub s//L/sub n/ for solitary drift waves, in contrast to linear waves

  2. The F-Region Equatorial Ionospheric Electrodynamics Drifts ...

    African Journals Online (AJOL)

    The ionospheric plasma drift is one of the most essential parameters for understanding the dynamics of ionospheric F-region. F-region electromagnetic drifts are calculated for three seasonal conditions from ionosonde observations acquired during quiet period of a typical year of high and low solar activity at Ibadan (7.4oN, ...

  3. Drift correction in a multichannel integrated optical Young interferometer

    NARCIS (Netherlands)

    Ymeti, Aurel; Greve, Jan; Lambeck, Paul; Wijn, Robert Raimond; Heideman, Rene; Kanger, Johannes S.

    2005-01-01

    We demonstrate that in a sensor based on a multichannel Young interferometer, the phase information obtained for different pairs of channels can be used to correct the long-term instability (drift) due to temperature differences between measuring and reference channels, the drift in the alignment of

  4. New Pulsars Discovered in Arecibo Drift-Scan Searches

    OpenAIRE

    McLaughlin, M. A.; Lorimer, D. R.; Champion, D. J.; Xilouris, K.; Arzoumanian, Z.; Backer, D. C.; Cordes, J. M.; Lommen, A. N.; Fruchter, A. S.

    2003-01-01

    We report on new pulsars discovered in Arecibo drift-scan data. Processing of 2200 square degrees of data has resulted in the detection of 41 known and 12 new pulsars. New pulsars include two millisecond pulsars, one solitary and one binary recycled pulsar, and one pulsar with very unusual pulse profile morphology and complex drifting subpulse behavior.

  5. Filtering and analysis on the random drift of FOG

    Science.gov (United States)

    Tian, Yun-Peng; Yang, Xiao-Jun; Guo, Yun-Zeng; Liu, Feng

    2015-10-01

    Fiber optic gyro (FOG) is an optical gyroscope which is based on the Sagnac effect and uses the optical fiber coil as light propagation channel. Gyro drift consists of two components: systemic drift and random drift. Systemic drift can be compensated by testing and calibrating. Random drift changes with time, so it becomes an important indicator to measure the precision of gyroscope, which has a great impact on the inertial navigation system. It can't be compensated by the simple method. Random drift is a main error of fiber optic gyro (FOG). The static output of FOG is a random project and it has more random noise when as the inertial navigation sensor, which will affect the measurement accuracy. It is an efficient method to reduce the random drift and improve the accuracy by modeling and compensation from the output of FOG. According to the characteristic of fiber optic gyro, the random drift model is studied. Using the time series method, the constant component of the random noise original data is extracted. After stationarity and normality tests, a normal random process is acquired. Based on this, the model is established using the recursive least squares, and then the model is applied to the normal Kalman and adaptive Kalman, finally the data is process with the filter. After experimental verification, the noise variance was reduced after filtering, and the effect is obvious.

  6. Drift wave studies in a linear multiple mirror

    International Nuclear Information System (INIS)

    Makowski, M.A.

    1983-06-01

    The drift wave is modeled by a linear kinetic theory which treats finite ion gyroradius, collisions, an electron temperature gradient, and trapped electrons. The theory predicts three unstable modes, only one of which is consistent with all of the above measurements. This instability is a Doppler shifted drift cyclotron instability modified by trapped particle effects

  7. Spin drift and spin diffusion currents in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Idrish Miah, M [Nanoscale Science and Technology Centre and School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)], E-mail: m.miah@griffith.edu.au

    2008-09-15

    On the basis of a spin drift-diffusion model, we show how the spin current is composed and find that spin drift and spin diffusion contribute additively to the spin current, where the spin diffusion current decreases with electric field while the spin drift current increases, demonstrating that the extension of the spin diffusion length by a strong field does not result in a significant increase in spin current in semiconductors owing to the competing effect of the electric field on diffusion. We also find that there is a spin drift-diffusion crossover field for a process in which the drift and diffusion contribute equally to the spin current, which suggests a possible method of identifying whether the process for a given electric field is in the spin drift or spin diffusion regime. Spin drift-diffusion crossover fields for GaAs are calculated and are found to be quite small. We derive the relations between intrinsic spin diffusion length and the spin drift-diffusion crossover field of a semiconductor for different electron statistical regimes. The findings resulting from this investigation might be important for semiconductor spintronics.

  8. Spin drift and spin diffusion currents in semiconductors

    Directory of Open Access Journals (Sweden)

    M Idrish Miah

    2008-01-01

    Full Text Available On the basis of a spin drift-diffusion model, we show how the spin current is composed and find that spin drift and spin diffusion contribute additively to the spin current, where the spin diffusion current decreases with electric field while the spin drift current increases, demonstrating that the extension of the spin diffusion length by a strong field does not result in a significant increase in spin current in semiconductors owing to the competing effect of the electric field on diffusion. We also find that there is a spin drift-diffusion crossover field for a process in which the drift and diffusion contribute equally to the spin current, which suggests a possible method of identifying whether the process for a given electric field is in the spin drift or spin diffusion regime. Spin drift-diffusion crossover fields for GaAs are calculated and are found to be quite small. We derive the relations between intrinsic spin diffusion length and the spin drift-diffusion crossover field of a semiconductor for different electron statistical regimes. The findings resulting from this investigation might be important for semiconductor spintronics.

  9. Spin drift and spin diffusion currents in semiconductors

    International Nuclear Information System (INIS)

    Idrish Miah, M

    2008-01-01

    On the basis of a spin drift-diffusion model, we show how the spin current is composed and find that spin drift and spin diffusion contribute additively to the spin current, where the spin diffusion current decreases with electric field while the spin drift current increases, demonstrating that the extension of the spin diffusion length by a strong field does not result in a significant increase in spin current in semiconductors owing to the competing effect of the electric field on diffusion. We also find that there is a spin drift-diffusion crossover field for a process in which the drift and diffusion contribute equally to the spin current, which suggests a possible method of identifying whether the process for a given electric field is in the spin drift or spin diffusion regime. Spin drift-diffusion crossover fields for GaAs are calculated and are found to be quite small. We derive the relations between intrinsic spin diffusion length and the spin drift-diffusion crossover field of a semiconductor for different electron statistical regimes. The findings resulting from this investigation might be important for semiconductor spintronics.

  10. Field-crop-sprayer potential drift measured using test bench

    NARCIS (Netherlands)

    Balsari, Paolo; Gil, Emilio; Marucco, Paolo; Zande, van de Jan C.; Nuyttens, David; Herbst, Andreas; Gallart, Montserrat

    2017-01-01

    Because of variations in environmental conditions, spray-drift field measurements following ISO 22866:2005 involve complicated and time-consuming experiments often with low repeatability. Therefore, simple, repeatable, and precise alternative drift assessment methods that are complementary to the

  11. Beam test of a large area silicon drift detector

    International Nuclear Information System (INIS)

    Castoldi, A.; Chinnici, S.; Gatti, E.; Longoni, A.; Palma, F.; Sampietro, M.; Rehak, P.; Ballocchi, G.; Kemmer, J.; Holl, P.; Cox, P.T.; Giacomelli, P.; Vacchi, A.

    1992-01-01

    The results from the tests of the first large area (4 x 4 cm 2 ) planar silicon drift detector prototype in a pion beam are reported. The measured position resolution in the drift direction is (σ=40 ± 10)μm

  12. Resistive drift wave turbulence in a three-dimensional geometry

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Michelsen, Poul; Naulin, V.

    1999-01-01

    The Hasegawa-Wakatani model describing resistive drift waves is investigated analytically and numerically in a three-dimensional periodic geometry. After an initial growth of the energy the drift waves couple nonlinearly to convective cells, which eventually dominate the system completely...

  13. Prediction of littoral drift with artificial neural networks

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, A.K.; Deo, M.C.; SanilKumar, V.

    of the rate of sand drift has still remained as a problem. The current study addresses this issue through the use of artificial neural networks (ANN). Feed forward networks were developed to predict the sand drift from a variety of causative variables...

  14. Drift tube suspension for high intensity linear accelerators

    International Nuclear Information System (INIS)

    Clark, D.C.; Frank, J.A.; Liska, D.J.; Potter, R.C.; Schamaun, R.G.

    1982-01-01

    The disclosure relates to a drift tube suspension for high intensity linear accelerators. The system comprises a series of box-sections girders independently adjustably mounted on a linear accelerator. A plurality of drift tube holding stems are individually adjustably mounted on each girder

  15. A drift free nernstian iridium oxide PH sensor

    NARCIS (Netherlands)

    Hendrikse, J.; Olthuis, Wouter; Bergveld, Piet

    1997-01-01

    A novel way of eliminating drift problems in metal oxide pH sensors is presented. The method employs a FET-structure under the electrode that uses the metal oxide as a gate contact. In addition to the enhanced drift properties, the new sensor has an almost ideal nernstian response. First a

  16. Obtaining the Space-Time Relationship of Drift Tubes from the Drift-Time Spectrum

    CERN Document Server

    Deile, Mario

    1999-01-01

    Autocalibration of MDT chambers requires a good start-value for the space-time relation\\-ship. This note presents two improvements on the ``Integration Method'': the first corrects for $\\delta$-rays, the second also takes into account resolution and efficiency effects. Both methods use only the drift-time spectrum. The new methods improve the rms error from 345\\,$\\mu$m to 80\\,$\\mu$m and 18\\,$\\mu$m respectively.

  17. Drift of suspended ferromagnetic particles due to the Magnus effect

    Science.gov (United States)

    Denisov, S. I.; Pedchenko, B. O.

    2017-01-01

    A minimal system of equations is introduced and applied to study the drift motion of ferromagnetic particles suspended in a viscous fluid and subjected to a time-periodic driving force and a nonuniformly rotating magnetic field. It is demonstrated that the synchronized translational and rotational oscillations of these particles are accompanied by their drift in a preferred direction, which occurs under the action of the Magnus force. We calculate both analytically and numerically the drift velocity of particles characterized by single-domain cores and nonmagnetic shells and show that there are two types of drift, unidirectional and bidirectional, which can be realized in suspensions composed of particles with different core-shell ratios. The possibility of using the phenomenon of bidirectional drift for the separation of core-shell particles in suspensions is also discussed.

  18. Drift estimation for single marker switching based imaging schemes.

    Science.gov (United States)

    Geisler, Claudia; Hotz, Thomas; Schönle, Andreas; Hell, Stefan W; Munk, Axel; Egner, Alexander

    2012-03-26

    In recent years, the diffraction barrier in fluorescence imaging has been broken and optical nanoscopes now routinely image with resolutions of down to 20 nm, an improvement of more than 10 fold. Because this allows imaging much smaller features and because all super-resolution approaches trade off speed for spatial resolution, mechanical instabilities of the microscopes become a limiting factor. Here, we propose a fully data-driven statistical registration method for drift detection and drift correction for single marker switching (SMS) imaging schemes, including a guideline for parameter choice and quality checks of the drift analysis. The necessary assumptions about the drift are minimal, allowing a model-free approach, but more specific models can easily be integrated. We determine the resulting performance on standard SMS measurements and show that the drift determination can be routinely brought to the range of precision achievable by fiducial marker-tracking methods.

  19. Drift Compression and Final Focus Options for Heavy Ion Fusion

    International Nuclear Information System (INIS)

    Hong Qin; Davidson, Ronald C.; Barnard, John J.; Lee, Edward P.

    2005-01-01

    A drift compression and final focus lattice for heavy ion beams should focus the entire beam pulse onto the same focal spot on the target. We show that this requirement implies that the drift compression design needs to satisfy a self-similar symmetry condition. For un-neutralized beams, the Lie symmetry group analysis is applied to the warm-fluid model to systematically derive the self-similar drift compression solutions. For neutralized beams, the 1-D Vlasov equation is solved explicitly, and families of self-similar drift compression solutions are constructed. To compensate for the deviation from the self-similar symmetry condition due to the transverse emittance, four time-dependent magnets are introduced in the upstream of the drift compression such that the entire beam pulse can be focused onto the same focal spot

  20. Assessment of the genetic diversity in five generations of a ...

    African Journals Online (AJOL)

    SERVER

    time, and genetic similarity could reach closer to 100% at 18-19 generation of this line. Key words: Litopenaeus vannamei, genetic diversity, genetic drift, ... of exotic pathogens (Batalha et al., 2002). Apart from the remarkable development of shrimp culture in ..... distance among the stocks (Table 4). y = 0.2948Ln(x) + 0.1385.

  1. The use of reproductive vigor descriptors in studying genetic ...

    African Journals Online (AJOL)

    The use of reproductive vigor descriptors in studying genetic variability in nine Tunisian faba bean ( Vicia faba L.) populations. ... The dendrogram based on Nei's genetic distance of the 9 populations using UPGMA method, show some genetic drift between populations. Key words: Faba bean, agromorphological traits, ...

  2. In-Drift Precipitates/Salts Model

    International Nuclear Information System (INIS)

    Mariner, P.

    2003-01-01

    As directed by ''Technical Work Plan For: Engineered Barrier System Department Modeling and Testing FY03 Work Activities'' (BSC 2003 [165601]), the In-Drift Precipitates/Salts (IDPS) model is developed and refined to predict the aqueous geochemical effects of evaporation in the proposed repository. The purpose of this work is to provide a model for describing and predicting the postclosure effects of evaporation and deliquescence on the chemical composition of water within the proposed Engineered Barrier System (EBS). Application of this model is to be documented elsewhere for the Total System Performance Assessment License Application (TSPA-LA). The principal application of this model is to be documented in REV 02 of ''Engineered Barrier System: Physical and Chemical Environment Model'' (BSC 2003 [165601]). The scope of this document is to develop, describe, and validate the IDPS model. This model is a quasi-equilibrium model. All reactions proceed to equilibrium except for several suppressed minerals in the thermodynamic database not expected to form under the proposed repository conditions within the modeling timeframe. In this revision, upgrades to the EQ3/6 code (Version 8.0) and Pitzer thermodynamic database improve the applicable range of the model. These new additions allow equilibrium and reaction-path modeling of evaporation to highly concentrated brines for potential water compositions of the system Na-K-H-Mg-Ca-Al-Cl-F-NO 3 -SO 4 -Br-CO 3 -SiO 2 -CO 2 -O 2 -H 2 O at temperatures in the range of 0 C to 125 C, pressures in the atmospheric range, and relative humidity in the range of 0 to 100 percent. This system applies to oxidizing conditions only, and therefore limits the model to applications involving oxidizing conditions. A number of thermodynamic parameters in the Pitzer database have values that have not been determined or verified for the entire temperature range. In these cases, the known values are used to approximate the values for the rest of

  3. In-Drift Precipitates/Salts Model

    Energy Technology Data Exchange (ETDEWEB)

    P. Mariner

    2003-10-21

    As directed by ''Technical Work Plan For: Engineered Barrier System Department Modeling and Testing FY03 Work Activities'' (BSC 2003 [165601]), the In-Drift Precipitates/Salts (IDPS) model is developed and refined to predict the aqueous geochemical effects of evaporation in the proposed repository. The purpose of this work is to provide a model for describing and predicting the postclosure effects of evaporation and deliquescence on the chemical composition of water within the proposed Engineered Barrier System (EBS). Application of this model is to be documented elsewhere for the Total System Performance Assessment License Application (TSPA-LA). The principal application of this model is to be documented in REV 02 of ''Engineered Barrier System: Physical and Chemical Environment Model'' (BSC 2003 [165601]). The scope of this document is to develop, describe, and validate the IDPS model. This model is a quasi-equilibrium model. All reactions proceed to equilibrium except for several suppressed minerals in the thermodynamic database not expected to form under the proposed repository conditions within the modeling timeframe. In this revision, upgrades to the EQ3/6 code (Version 8.0) and Pitzer thermodynamic database improve the applicable range of the model. These new additions allow equilibrium and reaction-path modeling of evaporation to highly concentrated brines for potential water compositions of the system Na-K-H-Mg-Ca-Al-Cl-F-NO{sub 3}-SO{sub 4}-Br-CO{sub 3}-SiO{sub 2}-CO{sub 2}-O{sub 2}-H{sub 2}O at temperatures in the range of 0 C to 125 C, pressures in the atmospheric range, and relative humidity in the range of 0 to 100 percent. This system applies to oxidizing conditions only, and therefore limits the model to applications involving oxidizing conditions. A number of thermodynamic parameters in the Pitzer database have values that have not been determined or verified for the entire temperature range. In these cases

  4. Drift curves from spray applications on commom bean crop

    Directory of Open Access Journals (Sweden)

    Mariana Rodrigues Bueno

    Full Text Available ABSTRACT In order to avoid the occurrence of drift in pesticide applications, it is fundamental to know the behavior of sprayed droplets. This study aimed to determine drift curves in pesticide applications on common bean crop under brazilian weather conditions, using different nozzle types and compared them with the "German" and "Dutch" drift prediction models. The experiment was conducted in Uberlândia, Minas Gerais/Brazil, in completely randomized design with ten replications and 4 x 20 split-plot arrangement in space. Drift deposited on collectors located over ground level was resulted by 150 L ha-1 carrier volume applications through four nozzle types (XR 11002 (fine droplets; AIXR 11002 (coarse droplets; TT 11002 (medium droplets; TTI 11002 (extremely coarse droplets, collected in 20 downwind distances, parallel to the crop line outside the target area, spaced by 2.5 m. The tracer rhodamine B was added to the spray to be quantified by fluorimetry. Drift prediction models adjusted by exponential functions were obtained considering the 90th percentile for XR, TT, AIXR and TTI nozzles. It is suggested to use the estimated drift models from this study for each nozzle type in drift prediction evaluations on bean crops under brazilian weather conditions.

  5. Nearshore drift dynamics of natural versus artificial seagrass wrack

    Science.gov (United States)

    Baring, Ryan J.; Fairweather, Peter G.; Lester, Rebecca E.

    2018-03-01

    Drifting macrophytes such as seagrass and macroalgae are commonly found washed ashore on sandy beaches but few studies have investigated the drift trajectories of macrophytes whilst near to the coast. This is the first study to investigate the surface drifting of small clumps of seagrass released at various distances from shore, across multiple days with contrasting wind and tidal conditions, in a large gulf in southern Australia. Natural and artificial radio-tagged seagrass units generally travelled in the same directions as tides but trajectories were variable across sampling days and when tagged units were released at different distances from shore. Natural and artificial units diverged from each other particularly on days when wind speeds increased but generally drifted in the same direction and ended up within close proximity to each other at the 6-h endpoint. During calm conditions, tagged seagrass units drifted with tides for 0.25-5 km and, during one sampling day when wind speeds increased, drifted for >5 km over the 6-h time period. Only tagged units that were released closest to shore stranded on sandy beaches within the six hours of observation, so it would be difficult to predict the eventual stranding location on shorelines for macrophytes released further offshore. This study provides evidence of the variability of macrophyte drift dynamics near to coastlines. Acknowledging this variability is essential for further understanding of the ecological significance of allochthonous material arriving at shorelines, which should be integrated into future research and management of sandy-beach ecosystems.

  6. Adaptive Online Sequential ELM for Concept Drift Tackling

    Science.gov (United States)

    Basaruddin, Chan

    2016-01-01

    A machine learning method needs to adapt to over time changes in the environment. Such changes are known as concept drift. In this paper, we propose concept drift tackling method as an enhancement of Online Sequential Extreme Learning Machine (OS-ELM) and Constructive Enhancement OS-ELM (CEOS-ELM) by adding adaptive capability for classification and regression problem. The scheme is named as adaptive OS-ELM (AOS-ELM). It is a single classifier scheme that works well to handle real drift, virtual drift, and hybrid drift. The AOS-ELM also works well for sudden drift and recurrent context change type. The scheme is a simple unified method implemented in simple lines of code. We evaluated AOS-ELM on regression and classification problem by using concept drift public data set (SEA and STAGGER) and other public data sets such as MNIST, USPS, and IDS. Experiments show that our method gives higher kappa value compared to the multiclassifier ELM ensemble. Even though AOS-ELM in practice does not need hidden nodes increase, we address some issues related to the increasing of the hidden nodes such as error condition and rank values. We propose taking the rank of the pseudoinverse matrix as an indicator parameter to detect “underfitting” condition. PMID:27594879

  7. Characterizing the nature of subpulse drifting in pulsars

    Science.gov (United States)

    Basu, Rahul; Mitra, Dipanjan

    2018-04-01

    We report a detailed study of subpulse drifting in four long-period pulsars. These pulsars were observed in the Meterwavelength Single-pulse Polarimetric Emission Survey and the presence of phase-modulated subpulse drifting was reported in each case. We carried out longer duration and more sensitive observations lasting 7000-12 000 periods in the frequency range 306-339 MHz. The drifting features were characterized in great detail, including the phase variations across the pulse window. For two pulsars, J0820-1350 and J1720-2933, the phases changed steadily across the pulse window. The pulsar J1034-3224 has five components. The leading component was very weak and was barely detectable in our single-pulse observations. The four trailing components showed subpulse drifting. The phase variations changed in alternate components with a reversal in the sign of the gradient. This phenomenon is known as bi-drifting. The pulsar J1555-3134 showed two distinct peak frequencies of comparable strengths in the fluctuation spectrum. The two peaks did not appear to be harmonically related and were most likely a result of different physical processes. Additionally, the long observations enabled us to explore the temporal variations of the drifting features. The subpulse drifting was largely constant with time but small fluctuations around a mean value were seen.

  8. Positive-feedback photometric drift in the PDS

    Science.gov (United States)

    Cornett, R. H.; Bohlin, R. C.; Hill, J. K.; Stecher, T. P.

    1984-01-01

    Digitizing flatfield images produces conditions in the Photometric Data System PDS which cause the measured density to drift by as much as .1 DN during a 10 minute interval. The drift occurs when the PDS, set up in equilibrium at fog level, subsequently scans a reasonably dense region for periods of longer than a few minutes. The drift is manifested primarily as a positive shift in density that is approximately the same for all densities. If the fog level is assumed to be in fact constant and is monitored during scans of flat fields, the PDS drift may be removed by subtracting the difference between the observed fog level and its assumed constant value for each pixel. This function is then smoothed and subtracted, as a function of scan line, from the measured density. The fog level is then adjusted to a standard value by adding a constant. The result is a flattened scan with PDS drift removed to the accuracy within which the fog level drift matches the drift at other levels.

  9. Performance of silicon drift detectors in a magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Castoldi, A.; Gatti, E.; Manzari, V.; Rehak, P. [Brookhaven National Lab., Upton, NY (United States)

    1997-11-11

    A study of the properties of silicon drift detectors in a magnetic field was carried out. A silicon drift detector with 41 anodes, providing unambiguous x and y position information, was used for measurements. Studies were done in three principal orientations of the detector relative to the direction of the magnetic field. The magnetic field was varied between 0 and 0.7 T and the drift field between 300 and 600 V/cm. Basic agreement with the theory of electron transport in semiconductors in a magnetic field was found. The transport properties of electrons in a magnetic field can be described by a mobility matrix. The components of the matrix depend on the electron mobility, Hall mobility and on the vector of the magnetic field. The precision of measurement was better than 0.2% for most of the parameters. For the electric field of a silicon drift detector, there is a first-order effect of the magnetic field only in one out of three principal directions. In this direction, the plane of the detector is perpendicular to the magnetic field and electrons drift at an angle {alpha} relative to the direction of the drift field. In two other principal directions, which are more important for tracking of the particles with drift detectors, there are no first-order magnetic effects. (orig.). 13 refs.

  10. Travelling fronts in stochastic Stokes’ drifts

    KAUST Repository

    Blanchet, Adrien

    2008-10-01

    By analytical methods we study the large time properties of the solution of a simple one-dimensional model of stochastic Stokes\\' drift. Semi-explicit formulae allow us to characterize the behaviour of the solutions and compute global quantities such as the asymptotic speed of the center of mass or the effective diffusion coefficient. Using an equivalent tilted ratchet model, we observe that the speed of the center of mass converges exponentially to its limiting value. A diffuse, oscillating front attached to the center of mass appears. The description of the front is given using an asymptotic expansion. The asymptotic solution attracts all solutions at an algebraic rate which is determined by the effective diffusion coefficient. The proof relies on an entropy estimate based on homogenized logarithmic Sobolev inequalities. In the travelling frame, the macroscopic profile obeys to an isotropic diffusion. Compared with the original diffusion, diffusion is enhanced or reduced, depending on the regime. At least in the limit cases, the rate of convergence to the effective profile is always decreased. All these considerations allow us to define a notion of efficiency for coherent transport, characterized by a dimensionless number, which is illustrated on two simple examples of travelling potentials with a sinusoidal shape in the first case, and a sawtooth shape in the second case. © 2008 Elsevier B.V. All rights reserved.

  11. The PHENIX Drift Chamber Front End Electroncs

    Science.gov (United States)

    Pancake, C.; Velkovska, J.; Pantuev, V.; Fong, D.; Hemmick, T.

    1998-04-01

    The PHENIX Drift Chamber (DC) is designed to operate in the high particle flux environment of the Relativistic Heavy Ion Collider and provide high resolution track measurements. It is segmented into 80 keystones with 160 readout channels each. The Front End Electronics (FEE) developed to meet the demanding operating conditions and the large number of readout channels of the DC will be discussed. It is based on two application specific integrated circuits: the ASD8 and the TMC-PHX1. The ASD8 chip contains 8 channels of bipolar amplifier-shaper-discriminator with 6 ns shaping time and ≈ 20 ns pulse width, which satisfies the two track resolution requirements. The TMC-PHX1 chip is a high-resolution multi-hit Time-to-Digital Converter. The outputs from the ASD8 are digitized in the Time Memory Cell (TMC) every (clock period)/32 or 0.78 ns (at 40 MHz), which gives the intrinsic time resolution of the system. A 256 words deep dual port memory keeps 6.4 μs time history of data at 40 MHz clock. Each DC keystone is supplied with 4 ASD8/TMC boards and one FEM board, which performs the readout of the TMC-PHX1's, buffers and formats the data to be transmitted over the Glink. The slow speed control communication between the FEM and the system is carried out over ARCNET. The full readout chain and the data aquisition system are being tested.

  12. Yucca Mountain drift scale test progress report

    Energy Technology Data Exchange (ETDEWEB)

    Apps, J.; Birkholzer, J.T.; Peterson,J.E.; Sonnenthal, E.; Spycher, N.; Tsang, Y.W.; Williams, K.H.

    1999-01-01

    The Drift Scale Test (DST) is part of the Exploratory Studies Facility (ESF) Thermal Test being conducted underground at the potential high-level nuclear waste repository at Yucca Mountain, Nevada. The purpose of the ESF Thermal Test is to acquire a more in-depth understanding of the coupled thermal, mechanical, hydrological, and chemical processes likely to be encountered in the rock mass surrounding the potential geological repository at Yucca Mountain. These processes are monitored by a multitude of sensors to measure the temperature, humidity, gas pressure, and mechanical displacement, of the rock formation in response to the heat generated by the heaters. In addition to collecting passive monitoring data, active hydrological and geophysical testing is also being carried out periodically in the DST. These active tests are intended to monitor changes in the moisture redistribution in the rock mass, to collect water and gas samples for chemical and isotopic analysis, and to detect microfiacturing due to heating. On December 3, 1998, the heaters in the DST were activated. The planned heating phase of the DST is 4 years, and the cooling phase following the power shutoff will be of similar duration. The present report summarizes interpretation and analysis of thermal, hydrological, chemical, and geophysical data for the first 6 months; it is the first of many progress reports to be prepared during the DST.

  13. Agricultural Spray Drift Concentrations in Rainwater, Stemflow ...

    Science.gov (United States)

    In order to study spray drift contribution to non-targeted habitats, pesticide concentrations were measured in stemflow (water flowing down the trunk of a tree during a rain event), rainfall, and amphibians in an agriculturally impacted wetland area near Tifton, Georgia, USA. Agricultural fields and sampling locations were located on the University of Georgia's Gibbs research farm. Samples were analyzed for >150 pesticides and over 20 different pesticides were detected in these matrices. Data indicated that herbicides (metolachlor and atrazine) and fungicides (tebuconazole) were present with the highest concentrations in stemflow, followed by those in rainfall and amphibian tissue samples. Metolachlor had the highest frequency of detection and highest concentration in rainfall and stemflow samples. Higher concentrations of pesticides were observed in stemflow for a longer period than rainfall. Furthermore, rainfall and stemflow concentrations were compared against aquatic life benchmarks and environmental water screening values to determine if adverse effects would potentially occur for non-targeted organisms. Of the pesticides detected, several had concentrations that exceeded the aquatic life benchmark value. The majority of the time mixtures were present in the different matrices, making it difficult to determine the potential adverse effects that these compounds will have on non-target species, due to unknown potentiating effects. These data help assess the

  14. Drift-Scale Coupled Processes (DST and TH Seepage) Models

    Energy Technology Data Exchange (ETDEWEB)

    J. Birkholzer; S. Mukhopadhyay

    2004-09-29

    The purpose of this report is to document drift-scale modeling work performed to evaluate the thermal-hydrological (TH) behavior in Yucca Mountain fractured rock close to waste emplacement drifts. The heat generated by the decay of radioactive waste results in rock temperatures elevated from ambient for thousands of years after emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, giving rise to water redistribution and altered flow paths. The predictive simulations described in this report are intended to investigate fluid flow in the vicinity of an emplacement drift for a range of thermal loads. Understanding the TH coupled processes is important for the performance of the repository because the thermally driven water saturation changes affect the potential seepage of water into waste emplacement drifts. Seepage of water is important because if enough water gets into the emplacement drifts and comes into contact with any exposed radionuclides, it may then be possible for the radionuclides to be transported out of the drifts and to the groundwater below the drifts. For above-boiling rock temperatures, vaporization of percolating water in the fractured rock overlying the repository can provide an important barrier capability that greatly reduces (and possibly eliminates) the potential of water seeping into the emplacement drifts. In addition to this thermal process, water is inhibited from entering the drift opening by capillary forces, which occur under both ambient and thermal conditions (capillary barrier). The combined barrier capability of vaporization processes and capillary forces in the near-field rock during the thermal period of the repository is analyzed and discussed in this report.

  15. Drift correction of the dissolved signal in single particle ICPMS.

    Science.gov (United States)

    Cornelis, Geert; Rauch, Sebastien

    2016-07-01

    A method is presented where drift, the random fluctuation of the signal intensity, is compensated for based on the estimation of the drift function by a moving average. It was shown using single particle ICPMS (spICPMS) measurements of 10 and 60 nm Au NPs that drift reduces accuracy of spICPMS analysis at the calibration stage and during calculations of the particle size distribution (PSD), but that the present method can again correct the average signal intensity as well as the signal distribution of particle-containing samples skewed by drift. Moreover, deconvolution, a method that models signal distributions of dissolved signals, fails in some cases when using standards and samples affected by drift, but the present method was shown to improve accuracy again. Relatively high particle signals have to be removed prior to drift correction in this procedure, which was done using a 3 × sigma method, and the signals are treated separately and added again. The method can also correct for flicker noise that increases when signal intensity is increased because of drift. The accuracy was improved in many cases when flicker correction was used, but when accurate results were obtained despite drift, the correction procedures did not reduce accuracy. The procedure may be useful to extract results from experimental runs that would otherwise have to be run again. Graphical Abstract A method is presented where a spICP-MS signal affected by drift (left) is corrected (right) by adjusting the local (moving) averages (green) and standard deviations (purple) to the respective values at a reference time (red). In combination with removing particle events (blue) in the case of calibration standards, this method is shown to obtain particle size distributions where that would otherwise be impossible, even when the deconvolution method is used to discriminate dissolved and particle signals.

  16. DRIFT-SCALE COUPLED PROCESSES (DST AND TH SEEPAGE) MODELS

    International Nuclear Information System (INIS)

    J.T. Birkholzer; S. Mukhopadhyay

    2005-01-01

    The purpose of this report is to document drift-scale modeling work performed to evaluate the thermal-hydrological (TH) behavior in Yucca Mountain fractured rock close to waste emplacement drifts. The heat generated by the decay of radioactive waste results in rock temperatures elevated from ambient for thousands of years after emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, giving rise to water redistribution and altered flow paths. The predictive simulations described in this report are intended to investigate fluid flow in the vicinity of an emplacement drift for a range of thermal loads. Understanding the TH coupled processes is important for the performance of the repository because the thermally driven water saturation changes affect the potential seepage of water into waste emplacement drifts. Seepage of water is important because if enough water gets into the emplacement drifts and comes into contact with any exposed radionuclides, it may then be possible for the radionuclides to be transported out of the drifts and to the groundwater below the drifts. For above-boiling rock temperatures, vaporization of percolating water in the fractured rock overlying the repository can provide an important barrier capability that greatly reduces (and possibly eliminates) the potential of water seeping into the emplacement drifts. In addition to this thermal process, water is inhibited from entering the drift opening by capillary forces, which occur under both ambient and thermal conditions (capillary barrier). The combined barrier capability of vaporization processes and capillary forces in the near-field rock during the thermal period of the repository is analyzed and discussed in this report

  17. Operation of a drift chamber vertex detector at the ISR

    International Nuclear Information System (INIS)

    Cockerill, D.; Fabjan, C.W.; Frandsen, P.; Hallgren, A.; Heck, B.; Hilke, H.J.; Hogue, R.; Killian, T.; Kreisler, M.; Lindsay, J.

    1980-01-01

    A cylindrical drift chamber with bicycle-wheel geometry has been constructed as the central detector for the Axial Field Spectrometer (AFS) at the ISR. To permit particle separation in jet-like events at high event rates, a considerable degree of azimuthal segmentation was chosen together with up to 42 space points per track. These points are obtained from measurements of drift time and charge division. Some particle identification is achieved with ionization loss sampling dE/dx). This contribution presents details on the construction and the operation of the drift chamber at the ISR and preliminary performance results. (orig.)

  18. Theory of drift and trapped-electron instabilities

    International Nuclear Information System (INIS)

    Chen, L.; Cheng, C.Z.; Frieman, E.A.

    1978-08-01

    This paper deals with the theoretical investigation of low-frequency drift and trapped-particle instabilities in systems with magnetic shear, by analytic and numerical procedures and by computer simulations. In particular, results are presented for calculations which demonstrate: (1) the stability of both collisionless and dissipative drift eigenmodes at long radial wavelengths (k/sub r/rho/sub i/ less than 1) in a sheared slab (one-dimensional) geometry; (2) the presence and structure of drift and trapped-electron eigenmodes in an axisymmetric toroidal (two-dimensional) geometry; and (3) the nonlinear evolution and resultant anomalous transport from trapped-electron instabilities

  19. Simplified Drift Analysis for Proving Lower Bounds in Evolutionary Computation

    DEFF Research Database (Denmark)

    Oliveto, Pietro S.; Witt, Carsten

    2011-01-01

    Drift analysis is a powerful tool used to bound the optimization time of evolutionary algorithms (EAs). Various previous works apply a drift theorem going back to Hajek in order to show exponential lower bounds on the optimization time of EAs. However, this drift theorem is tedious to read and to...... involving the complicated theorem can be redone in a much simpler and clearer way. In some cases even improved results may be achieved. Therefore, the simplified theorem is also a didactical contribution to the runtime analysis of EAs....

  20. The Development of Drift Wave Turbulence in Magnetic Reconnection

    Science.gov (United States)

    McMurtrie, L.; Drake, J. F.; Swisdak, M. M.

    2013-12-01

    An important feature in collisionless magnetic reconnection is the development of sharp discontinuities along the separatrices bounding the Alfvenic outflow. The typical scale length of these features is ρs (the Larmor radius based on the sound speed) for guide field reconnection. Temperature gradients in the inflowing plasma (as might be found in the magnetopause) can lead to instabilities at these separatrices, specifically drift wave turbulence. We present standalone 2D and 3D PIC simulations of drift wave turbulence to investigate scaling properties and growth rates. Further investigations of the relative importance of drift wave turbulence in the development of reconnection will also be considered.

  1. Seepage into drifts in unsaturated fractured rock at Yucca Mountain

    International Nuclear Information System (INIS)

    Birkholzer, Jens; Li, Guomin; Tsang, Chin-Fu; Tsang, Yvonne

    1998-01-01

    An important issue for the long-term performance of underground nuclear waste repository is the rate of seepage into the waste emplacement drifts. A prediction of the future seepage rate is particularly complicated for the potential repository site at Yucca Mountain, Nevada, as it is located in thick, partially saturated, fractured tuff formations. The long-term situation in the drifts several thousand years after waste emplacement will be characterized by a relative humidity level close to or equal to 100%, as the drifts will be sealed and unventilated, and the waste packages will have cooled. The underground tunnels will then act as capillary barriers for the unsaturated flow, ideally diverting water around them, if the capillary forces are stronger than gravity and viscous forces. Seepage into the drifts will only be possible if the hydraulic pressure in the rock close to the drift walls increases to positive values; i.e., the flow field becomes locally saturated. In the present work, they have developed and applied a methodology to study the potential rate of seepage into underground cavities embedded in a variably saturated, heterogeneous fractured rock formation. The fractured rock mass is represented as a stochastic continuum where the fracture permeabilities vary by several orders of magnitude. Three different realizations of random fracture permeability fields are generated, with the random permeability structure based on extensive fracture mapping, borehole video analysis, and in-situ air permeability testing. A 3-D numerical model is used to simulate the heterogeneous steady-state flow field around the drift, with the drift geometry explicitly represented within the numerical discretization grid. A variety of flow scenarios are considered assuming present-day and future climate conditions at Yucca Mountain. The numerical study is complemented by theoretical evaluations of the drift seepage problem, using stochastic perturbation theory to develop a better

  2. Modeling of Drift Effects on Solar Tower Concentrated Flux Distributions

    Directory of Open Access Journals (Sweden)

    Luis O. Lara-Cerecedo

    2016-01-01

    Full Text Available A novel modeling tool for calculation of central receiver concentrated flux distributions is presented, which takes into account drift effects. This tool is based on a drift model that includes different geometrical error sources in a rigorous manner and on a simple analytic approximation for the individual flux distribution of a heliostat. The model is applied to a group of heliostats of a real field to obtain the resulting flux distribution and its variation along the day. The distributions differ strongly from those obtained assuming the ideal case without drift or a case with a Gaussian tracking error function. The time evolution of peak flux is also calculated to demonstrate the capabilities of the model. The evolution of this parameter also shows strong differences in comparison to the case without drift.

  3. Silicon drift detector with reduced lateral diffusion: experimental results

    CERN Document Server

    Sonsky, J; Huizenga, John R; Hollander, R W; Eijk, C W E; Sarro, P M

    2000-01-01

    In a standard multi-anode silicon drift detector electron cloud broadening during the drifting towards the anode pixels deteriorates the energy and position resolution. This makes the detector less applicable for detection of low-energy X-rays. The signal charge sharing between several anodes can be eliminated by introducing sawtooth-shaped p sup + field strips. The sawtooth structure results in small electric fields directed parallel to the sensor surface and perpendicular to the drift direction which produce gutters. The drifting electrons are confined in these gutters of one saw tooth period wide. For a detector with a sawtooth period of 500 mu m, we have measured the maximum number of fully confined electrons as a function of the potential gutter depth induced by different sawtooth angles.

  4. Exactly soluble multidimensional Fokker-Planck equations with nonlinear drift

    International Nuclear Information System (INIS)

    Brand, H.; Schenzle, A.

    1981-01-01

    The time-dependent analytic solutions of three classes of multidimensional Fokker-Planck equations with nonlinear drift are presented together with eigenvalues which are complex and depend essentially on the correlation functions of the fluctuations. (orig.)

  5. IABP Drifting Buoy Pressure, Temperature, Position, and Interpolated Ice Velocity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The International Arctic Buoy Programme (IABP) maintains a network of drifting buoys to provide meteorological and oceanographic data for real-time operational...

  6. Professional Drift, "Yahweh Complex" Erode J-Education.

    Science.gov (United States)

    Riley, Sam G.

    1979-01-01

    Proposes that journalism education in general has been drifting in a strong research current for some years and is at present uncertain how to treat growing opposition by professional journalists to such a research emphasis. (RL)

  7. Nonlinear excitation of geodesic acoustic modes by drift waves

    International Nuclear Information System (INIS)

    Chakrabarti, N.; Singh, R.; Kaw, P. K.; Guzdar, P. N.

    2007-01-01

    In this paper, two mode-coupling analyses for the nonlinear excitation of the geodesic acoustic modes (GAMs) in tokamak plasmas by drift waves are presented. The first approach is a coherent parametric process, which leads to a three-wave resonant interaction. This investigation allows for the drift waves and the GAMs to have comparable scales. The second approach uses the wave-kinetic equations for the drift waves, which then couples to the GAMs. This requires that the GAM scale length be large compared to the wave packet associated with the drift waves. The resonance conditions for these two cases lead to specific predictions of the radial wave number of the excited GAMs

  8. Snow drift: acoustic sensors for avalanche warning and research

    Directory of Open Access Journals (Sweden)

    M. Lehning

    2002-01-01

    Full Text Available Based on wind tunnel measurements at the CSTB (Jules Verne facility in Nantes and based on field observations at the SLF experimental site Versuchsfeld Weissfluhjoch, two acoustic wind drift sensors are evaluated against different mechanical snow traps and one optical snow particle counter. The focus of the work is the suitability of the acoustic sensors for applications such as avalanche warning and research. Although the acoustic sensors have not yet reached the accuracy required for typical research applications, they can, however, be useful for snow drift monitoring to help avalanche forecasters. The main problem of the acoustic sensors is a difficult calibration that has to take into account the variable snow properties. Further difficulties arise from snow fall and high wind speeds. However, the sensor is robust and can be operated remotely under harsh conditions. It is emphasized that due to the lack of an accurate reference method for snow drift measurements, all sensors play a role in improving and evaluating snow drift models. Finally, current operational snow drift models and snow drift sensors are compared with respect to their usefulness as an aid for avalanche warning. While drift sensors always make a point measurement, the models are able to give a more representative drift index that is valid for a larger area. Therefore, models have the potential to replace difficult observations such as snow drift in operational applications. Current models on snow drift are either only applicable in flat terrain, are still too complex for an operational application (Lehning et al., 2000b, or offer only limited information on snow drift, such as the SNOWPACK drift index (Lehning et al., 2000a. On the other hand, snow drift is also difficult to measure. While mechanical traps (Mellor 1960; Budd et al., 1966 are probably still the best reference, they require more or less continuous manual operation and are thus not suitable for remote locations

  9. Transport of Na48 Drift Chambers to Dubna

    CERN Multimedia

    GOLOVATYUK, V

    2010-01-01

    On 22 July, in the occasion of the departure of the Na48 Drift Chambers from CERN, Mikhail Itkis (acting Director of the JIINR) and Rolf Heuer (CERN Director General) visited the NA62 experimental area.

  10. Nonparametric Bayesian drift estimation for multidimensional stochastic differential equations

    NARCIS (Netherlands)

    Gugushvili, S.; Spreij, P.

    2014-01-01

    We consider nonparametric Bayesian estimation of the drift coefficient of a multidimensional stochastic differential equation from discrete-time observations on the solution of this equation. Under suitable regularity conditions, we establish posterior consistency in this context.

  11. Predicting Escherichia coli's chemotactic drift under exponential gradient

    Science.gov (United States)

    Samanta, Sibendu; Layek, Ritwik; Kar, Shantimoy; Raj, M. Kiran; Mukhopadhyay, Sudipta; Chakraborty, Suman

    2017-09-01

    Bacterial species are known to show chemotaxis, i.e., the directed motions in the presence of certain chemicals, whereas the motion is random in the absence of those chemicals. The bacteria modulate their run time to induce chemotactic drift towards the attractant chemicals and away from the repellent chemicals. However, the existing theoretical knowledge does not exhibit a proper match with experimental validation, and hence there is a need for developing alternate models and validating experimentally. In this paper a more robust theoretical model is proposed to investigate chemotactic drift of peritrichous Escherichia coli under an exponential nutrient gradient. An exponential gradient is used to understand the steady state behavior of drift because of the logarithmic functionality of the chemosensory receptors. Our theoretical estimations are validated through the experimentation and simulation results. Thus, the developed model successfully delineates the run time, run trajectory, and drift velocity as measured from the experiments.

  12. Drift induced by repeated hydropeaking waves in controlled conditions

    Science.gov (United States)

    Maiolini, Bruno; Bruno, M. Cristina; Biffi, Sofia; Cashman, Matthew J.

    2014-05-01

    Repeated hydropeaking events characterize most alpine rivers downstream of power plants fed by high elevation reservoirs. The effects of hydropeaking on the benthic communities are well known, and usually each hydropeaking wave causes an increase in tractive force and changes in temperature and water quality. Simulations of hydropeaking in artificial system can help to disentangle the direct effects of the modified flow regime from impacts associated with other associated physio-chemical changes, and with the effects of river regulation and land-use changes that often accompany water resource development. In September 2013 we conducted a set of controlled simulations in five steel flumes fed by an Alpine stream (Fersina stream, Adige River catchment, Trentino, Italy), where benthic invertebrates can freely colonize the flumes. One flume was used as control with no change in flow, in the other four flumes we simulated an hydropeaking wave lasting six hours, and repeated for five consecutive days. Flow was increased by twice baseflow in two flumes, and three times in the other two. We collected benthic samples before the beginning (morning of day 1) and after the end (afternoon of day 5) of the set of simulations to evaluate changes in the benthic communities due to induced drift migration. During each simulation, we collected drifting organisms at short time intervals to assess the responses to: 1) the initial discharge increase, 2) the persistence of high flows for several hours; 3) the decrease of discharge to the baseflow; 4) the change in drift with each successive day. Preliminary results indicate typical strong increases of catastrophic drift on the onset of each simulated hydropeaking, drift responses proportional to the absolute discharge increase, a decrease in the drift responses over successive days. Different taxa responded with different patterns: taxa which resist tractive force increased in drift only during the periods of baseflow that follow the

  13. Low Drift Type N Thermocouples for Nuclear Applications

    International Nuclear Information System (INIS)

    Scervini, M.; Rae, C.

    2013-06-01

    Thermocouples are the most commonly used sensors for temperature measurement in nuclear reactors. They are crucial for the control of current nuclear reactors and for the development of GEN IV reactors. In nuclear applications thermocouples are strongly affected by intense neutron fluxes. As a result of the interaction with neutrons, the thermoelements of the thermocouples undergo transmutation, which produces a time dependent change in composition and, as a consequence, a time dependent drift of the thermocouple signal. Thermocouple drift can be very significant for in-pile temperature measurements and may render the temperature sensors unreliable after exposure to nuclear radiation for relatively short times compared to the life required for temperature sensors in nuclear applications. Previous experiences with type K thermocouples in nuclear reactors have shown that they are affected by neutron irradiation only to a limited extent. Similarly type N thermocouples are expected to be only slightly affected by neutron fluxes. Currently the use of Nickel based thermocouples is limited to temperatures lower than 1000 deg. C due to drift related to phenomena other than nuclear irradiation. In this work, undertaken as part of the European project METROFISSION, the drift of type N thermocouples has been investigated in the temperature range 600-1300 deg. C. The approach of this study is based on the attempt to separate the contributions of each thermo-element to drift. In order to identify the dominant thermo-element for drift, the contributions of both positive (NP) and negative (NN) thermo-elements to the total drift of 3.2 mm diameter MIMS thermocouples have been measured in each drift test using a pure Pt thermo-element as a reference. Conventional Inconel-600 sheathed type N thermocouples have been compared with type N thermocouples sheathed in a new alloy. At temperatures higher than 1000 deg. C conventional Inconel600 sheathed type N thermocouples can experience a

  14. Population genomics of the killer whale indicates ecotype evolution in sympatry involving both selection and drift

    Science.gov (United States)

    Moura, Andre E; Kenny, John G; Chaudhuri, Roy; Hughes, Margaret A; J Welch, Andreanna; Reisinger, Ryan R; de Bruyn, P J Nico; Dahlheim, Marilyn E; Hall, Neil; Hoelzel, A Rus

    2014-01-01

    The evolution of diversity in the marine ecosystem is poorly understood, given the relatively high potential for connectivity, especially for highly mobile species such as whales and dolphins. The killer whale (Orcinus orca) has a worldwide distribution, and individual social groups travel over a wide geographic range. Even so, regional populations have been shown to be genetically differentiated, including among different foraging specialists (ecotypes) in sympatry. Given the strong matrifocal social structure of this species together with strong resource specializations, understanding the process of differentiation will require an understanding of the relative importance of both genetic drift and local adaptation. Here we provide a high-resolution analysis based on nuclear single-nucleotide polymorphic markers and inference about differentiation at both neutral loci and those potentially under selection. We find that all population comparisons, within or among foraging ecotypes, show significant differentiation, including populations in parapatry and sympatry. Loci putatively under selection show a different pattern of structure compared to neutral loci and are associated with gene ontology terms reflecting physiologically relevant functions (e.g. related to digestion). The pattern of differentiation for one ecotype in the North Pacific suggests local adaptation and shows some fixed differences among sympatric ecotypes. We suggest that differential habitat use and resource specializations have promoted sufficient isolation to allow differential evolution at neutral and functional loci, but that the process is recent and dependent on both selection and drift. PMID:25244680

  15. Electron drift velocity measurements in liquid krypton-methane mixtures

    CERN Document Server

    Folegani, M; Magri, M; Piemontese, L

    1999-01-01

    Electron drift velocities have been measured in liquid krypton, pure and mixed with methane at different concentrations (1-10% in volume) versus electric field strength, and a possible effect of methane on electron lifetime has been investigated. While no effect on lifetime could be detected, since lifetimes were in all cases longer than what measurable, a very large increase in drift velocity (up to a factor 6) has been measured.

  16. Development of a prototype tapered cell drift chamber

    International Nuclear Information System (INIS)

    Blissett, J.A.; Hasell, D.K.; Kendall, E.W.; Payne, B.T.; Saxon, D.H.

    1984-06-01

    Drift chamber cells have been constructed and tested using an electron test beam facility at DESY. The cells were operated under different voltage conditions and with different gas mixtures at 1 bar. Aspects of the construction and operation are discussed. Resolutions were typically less than 100 microns. The dependence of the drift cell resolution on distance from the sense wire and operating conditions are presented. (author)

  17. Development of a prototype tapered cell drift chamber

    International Nuclear Information System (INIS)

    Blissett, J.A.; Hasell, D.K.; Kendall, E.W.; Payne, B.T.; Saxon, D.H.

    1984-01-01

    Drift chamber cells have been constructed and tested using an electron test beam facility at DESY. The cells were operated under different voltage conditions and with different gas mixtures at 1 bar. Aspects of the construction and operation are discussed. Resolutions were typically less than 100 μm. The dependence of the drift cell resolution on distance from the sense wire and operating conditions are presented. (orig.)

  18. The drift chamber electronics for the NA48 experiment

    CERN Document Server

    Arcidiacono, R; Chiozzi, S; Clemencic, M; Ramusino, A C; Damiani, C; Gianoli, A; Malaguti, R; Petrucci, F; Scarpa, M

    2004-01-01

    A drift chamber readout electronics for about 8000 channels with concurrent data recording and readout has been developed to update NA48 experiment existing system. Drift times are measured in bins of 1.56 ns with respect to the continuously running 40 MHz experiment clock. The architecture is based on commercially available hardware for cost effectiveness and flexibility. The design of the electronics is described, and results from data-taking runs are presented. (13 refs).

  19. SEEPAGE INTO DRIFTS IN UNSATRUATED FRACTURED ROCK AT YUCCA MOUNTAIN

    International Nuclear Information System (INIS)

    JENS BIRHOLZER; GUOMIN LI; CHIN-FU TSANG; YVONNE TSANG

    1998-01-01

    An important issue for the long-term performance of underground nuclear waste repositories is the rate of seepage into the waste emplacement drifts. A prediction of the future seepage rate is particularly complicated for the potential repository site at Yucca Mountain, Nevada, as it is located in thick, partially saturated, fractured tuff formations. The long-term situation in the drifts several thousand years after waste emplacement will be characterized by a relative humidity level close to or equal to 100%. as the drifts will be sealed and unventilated, and the waste packages will have cooled. The underground tunnels will then act as capillary barriers for the unsaturated flow, ideally diverting water around them, if the capillary forces are stronger than gravity and viscous forces. Seepage into the drifts will only be possible if the hydraulic pressure in the rock close to the drift walls increases to positive values; i.e., the flow field becomes locally saturated. In the present work, we have developed and applied a methodology to study the potential rate of seepage into underground cavities embedded in a variably saturated, heterogeneous fractured rock formation. The fractured rock mass is represented as a stochastic continuum where the fracture permeabilities vary by several orders of magnitude. Three different realizations of random fracture permeability fields are generated, with the random permeability structure based on extensive fracture mapping, borehole video analysis, and in-situ air permeability testing. A 3-D numerical model is used to simulate the heterogeneous steady-state flow field around the drift, with the drift geometry explicitly represented within the numerical discretization grid. A variety of flow scenarios are considered assuming present-day and future climate conditions at Yucca Mountain. The numerical study is complemented by theoretical evaluations of the drift seepage problem, using stochastic perturbation theory to develop a better

  20. Ageing tests for the MEG II drift chamber

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M., E-mail: marco.venturini@pi.infn.it [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy); INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Baldini, A.M. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Baracchini, E. [ICEPP, University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Cei, F.; D' Onofrio, A. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Dipartimento di Fisica, Universita di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Dussoni, S.; Galli, L.; Grassi, M. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Nicolò, D. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Dipartimento di Fisica, Universita di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Signorelli, G.; Tenchini, F. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Zermini, A. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Dipartimento di Fisica, Universita di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy)

    2016-07-11

    The MEG II drift chamber will track positrons from μ{sup +} decays in a very harsh environment. For testing the robustness of the chamber to ageing effects an irradiation facility was set up at INFN Pisa. - Highlights: • We built up an X-ray facility for ageing studies of particle detectors. • Stable irradiation conditions were obtained over one-month timescale. • A moderate gain loss is expected for the MEG II drift chamber.

  1. Measurements of electron drift velocity in pure isobutane

    International Nuclear Information System (INIS)

    Vivaldini, Tulio C.; Lima, Iara B.; Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B.; Ridenti, Marco A.; Pascholati, Paulo R.; Fonte, Paulo; Mangiarotti, Alessio

    2009-01-01

    In this work we report on preliminary results related to the dependence of the electron drift velocity for pure isobutane as a function of reduced electric field (E/N) in the range from 100 Td up to 216 Td. The measurements of electron drift velocity were based on the Pulsed Townsend technique. In order to validate the technique and analyzing non-uniformity effects, results for nitrogen are also presented and compared with a numerical simulation of the Bolsig+ code. (author)

  2. Measurements of electron drift velocity in pure isobutane

    Energy Technology Data Exchange (ETDEWEB)

    Vivaldini, Tulio C.; Lima, Iara B.; Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B., E-mail: ccbueno@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Ridenti, Marco A.; Pascholati, Paulo R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica. Lab. do Acelerador Linear; Fonte, Paulo; Mangiarotti, Alessio [Universidade de Coimbra (Portugal). Dept de Fisica. Lab. de Instrumentacao e Fisica Experimental de Particulas

    2009-07-01

    In this work we report on preliminary results related to the dependence of the electron drift velocity for pure isobutane as a function of reduced electric field (E/N) in the range from 100 Td up to 216 Td. The measurements of electron drift velocity were based on the Pulsed Townsend technique. In order to validate the technique and analyzing non-uniformity effects, results for nitrogen are also presented and compared with a numerical simulation of the Bolsig+ code. (author)

  3. Mechanical structure of the TOPAZ barrel drift chamber

    International Nuclear Information System (INIS)

    Morimoto, T.; Maruyama, K.; Okuno, H.

    1987-07-01

    A Barrel Drift Chamber (BDC) is constructed for the TOPAZ experiment at TRISTAN, KEK. The BDC has a cylindrical shape with dimensions of 325.2 cm in inner diameter, 347.2 cm in outer diameter and 500 cm long. It consists of 1232 drift tubes made of conductive plastic cathodes, which are staggered in four layers. In this report, a design of the mechanical structure and construction procedures are described in detail. (author)

  4. Drift natural convection and seepage at the Yucca Mountain repository

    Science.gov (United States)

    Halecky, Nicholaus Eugene

    The decay heat from radioactive waste that is to be disposed in the once proposed geologic repository at Yucca Mountain (YM) will significantly influence the moisture conditions in the fractured rock near emplacement tunnels (drifts). Additionally, large-scale convective cells will form in the open-air drifts and will serve as an important mechanism for the transport of vaporized pore water from the fractured rock, from the hot drift center to the cool drift end. Such convective processes would also impact drift seepage, as evaporation could reduce the build up of liquid water at the tunnel wall. Characterizing and understanding these liquid water and vapor transport processes is critical for evaluating the performance of the repository, in terms of water- induced canister corrosion and subsequent radionuclide containment. To study such processes, we previously developed and applied an enhanced version of TOUGH2 that solves for natural convection in the drift. We then used the results from this previous study as a time-dependent boundary condition in a high-resolution seepage model, allowing for a computationally efficient means for simulating these processes. The results from the seepage model show that cases with strong natural convection effects are expected to improve the performance of the repository, since smaller relative humidity values, with reduced local seepage, form a more desirable waste package environment.

  5. Measurement of Spray Drift with a Specifically Designed Lidar System

    Directory of Open Access Journals (Sweden)

    Eduard Gregorio

    2016-04-01

    Full Text Available Field measurements of spray drift are usually carried out by passive collectors and tracers. However, these methods are labour- and time-intensive and only provide point- and time-integrated measurements. Unlike these methods, the light detection and ranging (lidar technique allows real-time measurements, obtaining information with temporal and spatial resolution. Recently, the authors have developed the first eye-safe lidar system specifically designed for spray drift monitoring. This prototype is based on a 1534 nm erbium-doped glass laser and an 80 mm diameter telescope, has scanning capability, and is easily transportable. This paper presents the results of the first experimental campaign carried out with this instrument. High coefficients of determination (R2 > 0.85 were observed by comparing lidar measurements of the spray drift with those obtained by horizontal collectors. Furthermore, the lidar system allowed an assessment of the drift reduction potential (DRP when comparing low-drift nozzles with standard ones, resulting in a DRP of 57% (preliminary result for the tested nozzles. The lidar system was also used for monitoring the evolution of the spray flux over the canopy and to generate 2-D images of these plumes. The developed instrument is an advantageous alternative to passive collectors and opens the possibility of new methods for field measurement of spray drift.

  6. Quantifying vapor drift of dicamba herbicides applied to soybean.

    Science.gov (United States)

    Egan, J Franklin; Mortensen, David A

    2012-05-01

    Recent advances in biotechnology have produced cultivars of corn, soybean, and cotton resistant to the synthetic-auxin herbicide dicamba. This technology will allow dicamba herbicides to be applied in new crops, at new periods in the growing season, and over greatly expanded areas, including postemergence applications in soybean. From past and current use in corn and small grains, dicamba vapor drift and subsequent crop injury to sensitive broadleaf crops has been a frequent problem. In the present study, the authors measured dicamba vapor drift in the field from postemergence applications to soybean using greenhouse-grown soybean as a bioassay system. They found that when the volatile dimethylamine formulation is applied, vapor drift could be detected at mean concentrations of 0.56 g acid equivalent dicamba/ha (0.1% of the applied rate) at 21 m away from a treated 18.3 × 18.3 m plot. Applying the diglycolamine formulation of dicamba reduced vapor drift by 94.0%. With the dimethylamine formulation, the extent and severity of vapor drift was significantly correlated with air temperature, indicating elevated risks if dimethylamine dicamba is applied early to midsummer in many growing regions. Additional research is needed to more fully understand the effects of vapor drift exposures to nontarget crops and wild plants. Copyright © 2012 SETAC.

  7. Characterising large area silicon drift detectors with MOS injectors

    International Nuclear Information System (INIS)

    Bonvicini, V.; Rashevsky, A.; Vacchi, A.

    1999-01-01

    In the framework of the INFN DSI project, the first prototypes of a large-area Silicon Drift Detector (SDD) have been designed and produced on 5'' diameter wafers of Neutron Transmutation Doped (NTD) silicon with a resistivity of 3000 Ω·cm. The detector is a 'butterfly' bi-directional structure with a drift length of 32 mm and the drifting charge is collected by two arrays of anodes having a pitch of 200 μm. The high-voltage divider is integrated on-board and is realised with p + implantations. For test and calibration purposes, the detector has a new type of MOS injector. The paper presents results obtained to injecting charge at the maximum drift distance (32mm) from the anodes by means of the MOS injecting structure, As front-end electronics, the authors have used a 32-channels low-noise bipolar VLSI circuit (OLA, Omni-purpose Low-noise Amplifer) specifically designed for silicon drift detectors. The uniformity of the drift time in different regions of the sensitive area and its dependence on the ambient temperature are studied

  8. Drift scale thermomechanical analysis for thermal loading and retrievability studies

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, F.C.

    1995-12-31

    Currently, the repository portion of the Mined Geologic Disposal System for the disposal of spent nuclear fuel and high level radioactive waste is in the advanced conceptual design (ACD) stage. As a part of the Thermal Loading Systems Study and the Retrievability Period Systems Study, a numerical method was used to estimate the stability of emplacement drifts. Drift stability is an important performance issue, particularly for the concept of a waste package (WP) in an open drift. Drift stability is both a preclosure and postclosure issue. Specifically, preclosure worker safety and WP retrievability can be affected by drift stability. Important postclosure drift stability issues are the potential for rockfall which might damage a WP or the potential formation of cracks and upheaval of rock masses which may alter the hydrologic performance of the repository. In the current study, thermomechanical analyses, using the Discontinuous Deformation Analysis (DDA) numerical code, were performed to support the thermal loading study and the retrievability study. The coupled effects between thermal and mechanical behavior induced by the excavation, thermal loading and rapid cooling were analyzed using rock-mass models. Input data for the jointed-rock pattern, in situ stress condition, and the material properties of intact rock and rock joints were adopted from the Yucca Mountain Site Characterization Project.

  9. Achieving stringent climate targets. An analysis of the role of transport and variable renewable energies using energy-economy-climate models

    Energy Technology Data Exchange (ETDEWEB)

    Pietzcker, Robert Carl

    2014-07-01

    Anthropogenic climate change is threatening the welfare of mankind. Accordingly, policy makers have repeatedly stated the goal of slowing climate change and limiting the increase of global mean temperature to less than 2 C above pre-industrial times (the so-called ''two degree target''). Stabilizing the temperature requires drastic reductions of greenhouse gas (GHG) emissions to nearly zero. As the global system of energy supply currently relies on fossil fuels, reducing GHG emissions can only be achieved through a full-scale transformation of the energy system. This thesis investigates the economic requirements and implications of different scenarios that achieve stringent climate mitigation targets. It starts with the analysis of characteristic decarbonization patterns and identifies two particularly relevant aspects of mitigation scenarios: deployment of variable renewable energies (VRE) and decarbonization of the transport sector. After investigating these fields in detail, we turned towards one of the most relevant questions for policy makers and analyzed the trade-off between the stringency of a climate target and its economic requirements and implications. All analyses are based on the improvement, application, comparison, and discussion of large-scale IAMs. The novel ''mitigation share'' metric allowed us to identify the relevance of specific technology groups for mitigation and to improve our understanding of the decarbonization patterns of different energy subsectors. It turned out that the power sector is decarbonized first and reaches lowest emissions, while the transport sector is slowest to decarbonize. For the power sector, non-biomass renewable energies contribute most to emission reductions, while the transport sector strongly relies on liquid fuels and therefore requires biomass in combination with carbon capture and sequestration (CCS) to reduce emissions. An in-depth investigation of the solar power

  10. Stringent and reproducible tetracycline-regulated transgene expression by site-specific insertion at chromosomal loci with pre-characterised induction characteristics

    Directory of Open Access Journals (Sweden)

    Papanastasiou Antigoni M

    2007-05-01

    Full Text Available Abstract Background The ability to regulate transgene expression has many applications, mostly concerning the analysis of gene function. Desirable induction characteristics, such as low un-induced expression, high induced expression and limited cellular heterogeneity, can be seriously impaired by chromosomal position effects at the site of transgene integration. Many clones may therefore need to be screened before one with optimal induction characteristics is identified. Furthermore, such screens must be repeated for each new transgene investigated, and comparisons between clones with different transgenes is complicated by their different integration sites. Results To circumvent these problems we have developed a "screen and insert" strategy in which clones carrying a transgene for a fluorescent reporter are first screened for those with optimal induction characteristics. Site-specific recombination (SSR is then be used repeatedly to insert any new transgene at the reporter transgene locus of such clones so that optimal induction characteristics are conferred upon it. Here we have tested in a human fibrosarcoma cell line (HT1080 two of many possible implementations of this approach. Clones (e.g. Rht14-10 in which a GFP reporter gene is very stringently regulated by the tetracycline (tet transactivator (tTA protein were first identified flow-cytometrically. Transgenes encoding luciferase, I-SceI endonuclease or Rad52 were then inserted by SSR at a LoxP site adjacent to the GFP gene resulting stringent tet-regulated transgene expression. In clone Rht14-10, increases in expression from essentially background levels (+tet to more than 104-fold above background (-tet were reproducibly detected after Cre-mediated insertion of either the luciferase or the I-SceI transgenes. Conclusion Although previous methods have made use of SSR to integrate transgenes at defined sites, none has effectively combined this with a pre-selection step to identify

  11. Drift-Scale Coupled Processes (DST and THC Seepage) Models

    International Nuclear Information System (INIS)

    Sonnenthale, E.

    2001-01-01

    The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M and O) 2000 [1534471]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M and O 2000 [153309]). These models include the Drift Scale Test (DST) THC Model and several THC seepage models. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal loading conditions, and predict the chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: Performance Assessment (PA); Near-Field Environment (NFE) PMR; Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); and UZ Flow and Transport Process Model Report (PMR). The work scope for this activity is presented in the TWPs cited above, and summarized as follows: Continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data, sensitivity and validation studies described in this AMR are

  12. Historic and future trends of vehicle emissions in Beijing, 1998-2020: A policy assessment for the most stringent vehicle emission control program in China

    Science.gov (United States)

    Zhang, Shaojun; Wu, Ye; Wu, Xiaomeng; Li, Mengliang; Ge, Yunshan; Liang, Bin; Xu, Yueyun; Zhou, Yu; Liu, Huan; Fu, Lixin; Hao, Jiming

    2014-06-01

    As a pioneer in controlling vehicle emissions within China, Beijing released the Clean Air Action Plan 2013-2017 document in August 2013 to improve its urban air quality. It has put forward this plan containing the most stringent emission control policies and strategies to be adopted for on-road vehicles of Beijing. This paper estimates the historic and future trends and uncertainties in vehicle emissions of Beijing from 1998 to 2020 by applying a new emission factor model for the Beijing vehicle fleet (EMBEV). Our updated results show that total emissions of CO, THC, NOx and PM2.5 from the Beijing vehicle fleet are 507 (395-819) kt, 59.1 (41.2-90.5) kt, 74.7 (54.9-103.9) kt and 2.69 (1.91-4.17) kt, respectively, at a 95% confidence level. This represents significant reductions of 58%, 59%, 31% and 62%, respectively, relative to the total vehicle emissions in 1998. The past trends clearly posed a challenge to NOx emission mitigation for the Beijing vehicle fleet, especially in light of those increasing NOx emissions from heavy-duty diesel vehicles (HDDVs) which have partly offset the reduction benefit from light-duty gasoline vehicles (LDGVs). Because of recently announced vehicle emission controls to be adopted in Beijing, including tighter emissions standards, limitations on vehicle growth by more stringent license control, promotion of alternative fuel technologies (e.g., natural gas) and the scrappage of older vehicles, estimated vehicle emissions in Beijing will continue to be mitigated by 74% of CO, 68% of THC, 56% of NOx and 72% of PM2.5 in 2020 compared to 2010 levels. Considering that many of the megacities in China are facing tremendous pressures to mitigate emissions from on-road vehicles, our assessment will provide a timely case study of significance for policy-makers in China.

  13. Characteristic parameters of drift chambers calculation; Calculo de los parametros caracteristicos de camaras de deriva

    Energy Technology Data Exchange (ETDEWEB)

    Duran, I.; Martinez-Laso, L.

    1989-07-01

    We present here the methods we used to analyse the characteristic parameters of drift chambers. The algorithms to calculate the electric potential in any point for any drift chamber geometry are presented. We include the description of the programs used to calculate the electric field, the drift paths, the drift velocity and the drift time. The results and the errors are discussed. (Author) 7 refs.

  14. A future for drifting seismic networks

    Science.gov (United States)

    Simons, F. J.; Nolet, G.; Babcock, J.

    2007-12-01

    One-dimensional, radial Earth models are sufficiently well constrained to accurately locate earthquakes and calculate the paths followed by seismic rays. The differences between observations and theoretical predictions of seismograms in such Earth models can be used to reconstruct the three-dimensional wave speed distribution in the regions sampled by the seismic waves, by the technique of seismic tomography. Caused by thermal, compositional, and textural variations, wave speed anomalies remain the premier data source to fully understand the structure and evolution of our planet, from the scale of mantle convection and the mechanisms of heat transfer from core to surface to the international between the deep Earth and surface processes such as plate motion and crustal deformation. Unequal geographical data coverage continues to fundamentally limit the quality of tomographic reconstructions of seismic wave speeds in the interior of the Earth. Only at great cost can geophysicists overcome the difficulties of placing seismographs on the two thirds of the Earth's surface that is covered by oceans. The lack of spatial data coverage strongly hampers the determination of the structure of the Earth in the uncovered regions: all 3-D Earth models are marked by blank spots in areas, distributed throughout the Earth, where little or no information can be obtained. As a possible solution to gaining equal geographic data coverage, we have developed MERMAID, a prototype mobile receiver that could provide an easy, cost-effective way to collect seismic data in the ocean. It is a modification of the robotic floating instruments designed and used by oceanographers. Like them, MERMAID spends its life at depth but is capable of surfacing using a pump and bladder. We have equipped it with a hydrophone to record water pressure variations induced by compressional (P) waves. Untethered and passively drifting, such a floating seismometer will surface upon detection of a "useful" seismic

  15. Development of a tapered cell drift chamber. Pt. 2

    International Nuclear Information System (INIS)

    Blissett, J.A.; Hasell, D.K.; Parham, A.G.; Payne, B.T.; Saxon, D.H.

    1986-01-01

    Several designs for drift cells have been constructed and tested in an electron beam at DESY. The designs tested consisted of pairs of adjacent tapered cells, of eight sense wires each, to simulate a portion of a layer of drift cells in a central tracking detector. For operation in a magnetic field three different tilts for the plane of the sense wires (0 0 , 20 0 and 45 0 ) were used. Tests were made to study the operation and resolution of the drift cells under a variety of conditions. Ar:C 2 H 6 (50:50) and Ar:CO 2 :CH 4 (90:9:1) gas mixtures were used at absolute pressures of 1 to 4 bar for the former and at 1 bar for the latter. Measurements were made at different electric drift fields in conjunction with magnetic fields varying from 0 to 1.82 T. Aspects of the construction, electronics and operation are discussed and results regarding the resolution as a function of drift distance and operating conditions are presented with some model calculation. (orig.)

  16. Drift current under the action of wind and waves

    International Nuclear Information System (INIS)

    Youssef, M.; Spaulding, M.

    1993-01-01

    Accurate estimates of sea surface drift currents are critical to forecasting oil spill transport and fate. Most existing spill models employ a drift factor and deflection angle, based on local wind speed, to estimate the sea surface drift vector. The effects of wind-induced shear and wave-induced transport are lumped together in this formulation. In the present approach, the conservation of momentum, water mass, and turbulent energy equations are solved using an implicit finite difference method to predict the vertical distribution of current, turbulent energy, and eddy viscosity at one point. The model includes coupling between the wave- and shear-induced currents. Input energy from the atmosphere to the turbulent energy and current fields are represented through free-surface boundary conditions. The numerical model showed excellent agreement compared to an analytic solution of the wind-forced shear flow problem. The model was applied to predict surface drift currents for varying wind speeds and predicted results in general agreement with field observations and other numerical and theoretical studies. The model predicted drift factor F (%) and deflection angle A (degrees) decrease with increasing wind speed W (m/s), and can be approximated by the following curve fits: F=3.91-0.318W, A=23.627-7.97 log W. The model was applied to three intentional oil spills conducted on the Norwegian continental shelf in 1991 and predicted the observed trajectories with reasonable accuracy. 24 refs., 17 figs

  17. Development of the statisticlal analysis methods for managing setpoint drifts

    International Nuclear Information System (INIS)

    Jang, S. C.; Lim, T. J.

    2004-08-01

    The nuclear industry has generally accepted the statistical approach suggested in ISA-67.04(1994) for ensuring that the setpoints for safety-related instrumentation are established and maintained within the technical specification limits (NRC RG1.105, 1999). However, the current methodologies of the document may be insufficient to manage the setpoint drift of instrumentation devices, because they are basically designed to determine an instrument setpoint using statistical prediction techniques. In this report, we propose a new statistical analysis procedure composed of six steps for the management of the setpoint drift using the plant-specific as-found/as-left data of the instrumentation devices. For the applicability of the proposed method, an example is illustrated based on practical as-found/as-left data obtained from the channel functional test of a bistable at a one-month surveillance interval in a Korean Standard Nuclear Power Plant. All analysis were performed using the SeDA(Setpoint Drift Analysis) program that has been developed in accordance with the new 6-step procedure. The use of more statistical graphic tools can facilitate the process of the previous setpoint drift evaluation. The scope of the drift analysis is enlarged by the adoption of non-parametric statistical methods from the view point of the methodology. Several statistical process control techniques will provide the plant staff with more efficiency for the management of the instrumentation device

  18. MALDI-TOF Baseline Drift Removal Using Stochastic Bernstein Approximation

    Directory of Open Access Journals (Sweden)

    Howard Daniel

    2006-01-01

    Full Text Available Stochastic Bernstein (SB approximation can tackle the problem of baseline drift correction of instrumentation data. This is demonstrated for spectral data: matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF data. Two SB schemes for removing the baseline drift are presented: iterative and direct. Following an explanation of the origin of the MALDI-TOF baseline drift that sheds light on the inherent difficulty of its removal by chemical means, SB baseline drift removal is illustrated for both proteomics and genomics MALDI-TOF data sets. SB is an elegant signal processing method to obtain a numerically straightforward baseline shift removal method as it includes a free parameter that can be optimized for different baseline drift removal applications. Therefore, research that determines putative biomarkers from the spectral data might benefit from a sensitivity analysis to the underlying spectral measurement that is made possible by varying the SB free parameter. This can be manually tuned (for constant or tuned with evolutionary computation (for .

  19. Preliminary drift design analyses for nuclear waste repository in tuff

    International Nuclear Information System (INIS)

    Hardy, M.P.; Brechtel, C.E.; Goodrich, R.R.; Bauer, S.J.

    1990-01-01

    The Yucca Mountain Project (YMP) is examining the feasibility of siting a repository for high-level nuclear waste at Yucca Mountain, on and adjacent to the Nevada Test Site (NTS). The proposed repository will be excavated in the Topopah Spring Member, which is a moderately fractured, unsaturated, welded tuff. Excavation stability will be required during construction, waste emplacement, retrieval (if required), and closure to ensure worker safety. The subsurface excavations will be subject to stress changes resulting from thermal expansion of the rock mass and seismic events associated with regional tectonic activity and underground nuclear explosions (UNEs). Analyses of drift stability are required to assess the acceptable waste emplacement density, to design the drift shapes and ground support systems, and to establish schedules and cost of construction. This paper outlines the proposed methodology to assess drift stability and then focuses on an example of its application to the YMP repository drifts based on preliminary site data. Because site characterization activities have not begun, the database currently lacks the extensive site-specific field and laboratory data needed to form conclusions as to the final ground support requirements. This drift design methodology will be applied and refined as more site-specific data are generated and as analytical techniques and methodologies are verified during the site characterization process

  20. On Ion Drifts and Neutral Winds in Titan's Thermosphere

    Science.gov (United States)

    Shebanits, Oleg; Wahlund, Jan-Erik; Edberg, Niklas J. T.; Andrews, David J.; Crary, Frank J.; Wellbrock, Anne; Coates, Andrew; Mandt, Kathleen E.; Waite, J. Hunter, Jr.

    2015-04-01

    Saturn's largest moon Titan hosts an atmosphere with complex organic chemistry initiated in the ionosphere. The nightside chemistry may be influenced by the ion transport from the dayside ionosphere. In turn, ion transport (ion drifts) may be affected by the neutral winds, which cannot be measured directly by Cassini. In this study we derive the ion drifts along the spacecraft trajectories based on analysis of in-situ measurements of electron and ion fluxes, positive and negative ion masses and the magnetic field. Data from Titan flybys TA to T100 was included (Oct 2005 - Apr 2014), of which 55 flybys were below 1400 km and 48 below 1200 km altitude. From the electron and ion flux measurements three regions were observed: 1) above 1600 km, ions are ExB-drifting (frozen into the fields), 2) 1100-1600 km altitudes, dynamo-region, ions drift in opposite directions (perpendicular to B) and 3) 880-1100 km altitude (upper limit depends on convection electric field strength), ions are following neutrals and ion drifts translate to neutral winds of 0.5-2.5 km/s with weaker winds on the dayside of Titan's ionosphere.

  1. Construction and operation of a drift-collection calorimeter

    International Nuclear Information System (INIS)

    Ambats, I.; Ayres, D.S.; Dawson, J.W.

    1984-01-01

    Large areas planar drift chambers with long drift distance (up to 50 cm) have been developed for possible use in the new Soudan 2 nucleon decay detector. Design goals included fine sampling to determine the topology of complex events with several low-energy tracks. The large scale of the experiment (> 1000 metric tons) required large area inexpensive chambers, which also had good position resolution and multi-track separation. The chambers were to be installed between thin sheets of steel to form a finegrained detector. A second goal was the sampling of dE/dx with each position measurement, in order to determine the direction and particle identity of each track. In this paper we report on the construction and operation of a prototype dectector consisting of 50 chambers, separated by 3 mm-thick steel plates. Readout of drift time and pulse height from anode wires and an orthogonal grid of bussed cathode pads utilized 6-bit flash ADC's. This application of the drift-collection calorimeter technique to a nucleon decay detector follows the investigation by a number of groups of calorimeters for high energy detectors based on long drifting

  2. DRIFT ANALYSIS ON NEURAL NETWORK MODEL OF HEAT EXCHANGER FOULING

    Directory of Open Access Journals (Sweden)

    M. RAMASAMY

    2008-04-01

    Full Text Available Neural Networks (NN provide a good platform for modeling complex and poorly understood systems in many different fields. Due to the empirical nature of NN, it is typically valid only for small operating windows. As the process drifts, the prediction accuracy of such models deteriorates very much rendering the models unfit. An on-line mechanism to follow the drift in the process is necessary in order to retrain the NN models. Information Criteria have been reported to be used for the selection of relevant input variables and determination of optimal NN model structures. This paper proposes the use of information criteria for tracking the model prediction accuracy and provides an algorithm for retraining the model. A heat exchanger in a refinery Crude Preheat Train (CPT has been used as a case study. The operational problems of heat exchangers in CPT are compounded by the varying nature of crude blends and the complex fouling phenomenon. Fouling develops slowly and therefore the drift in the process occurs on a slower scale. The performance of a NN fouling model, developed using industrial data is investigated for drift. Model performance at different operating conditions is evaluated and it has been shown that drifts do occur in the process. An algorithm for retraining NN model has been proposed.

  3. Incremental learning of concept drift in nonstationary environments.

    Science.gov (United States)

    Elwell, Ryan; Polikar, Robi

    2011-10-01

    We introduce an ensemble of classifiers-based approach for incremental learning of concept drift, characterized by nonstationary environments (NSEs), where the underlying data distributions change over time. The proposed algorithm, named Learn(++). NSE, learns from consecutive batches of data without making any assumptions on the nature or rate of drift; it can learn from such environments that experience constant or variable rate of drift, addition or deletion of concept classes, as well as cyclical drift. The algorithm learns incrementally, as other members of the Learn(++) family of algorithms, that is, without requiring access to previously seen data. Learn(++). NSE trains one new classifier for each batch of data it receives, and combines these classifiers using a dynamically weighted majority voting. The novelty of the approach is in determining the voting weights, based on each classifier's time-adjusted accuracy on current and past environments. This approach allows the algorithm to recognize, and act accordingly, to the changes in underlying data distributions, as well as to a possible reoccurrence of an earlier distribution. We evaluate the algorithm on several synthetic datasets designed to simulate a variety of nonstationary environments, as well as a real-world weather prediction dataset. Comparisons with several other approaches are also included. Results indicate that Learn(++). NSE can track the changing environments very closely, regardless of the type of concept drift. To allow future use, comparison and benchmarking by interested researchers, we also release our data used in this paper. © 2011 IEEE

  4. Sample drift correction in 3D fluorescence photoactivation localization microscopy.

    Science.gov (United States)

    Mlodzianoski, Michael J; Schreiner, John M; Callahan, Steven P; Smolková, Katarina; Dlasková, Andrea; Santorová, Jitka; Ježek, Petr; Bewersdorf, Joerg

    2011-08-01

    The recent development of diffraction-unlimited far-field fluorescence microscopy has overcome the classical resolution limit of ~250 nm of conventional light microscopy by about a factor of ten. The improved resolution, however, reveals not only biological structures at an unprecedented resolution, but is also susceptible to sample drift on a much finer scale than previously relevant. Without correction, sample drift leads to smeared images with decreased resolution, and in the worst case to misinterpretation of the imaged structures. This poses a problem especially for techniques such as Fluorescence Photoactivation Localization Microscopy (FPALM/PALM) or Stochastic Optical Reconstruction Microscopy (STORM), which often require minutes recording time. Here we discuss an approach that corrects for three-dimensional (3D) drift in images of fixed samples without the requirement for fiduciary markers or instrument modifications. Drift is determined by calculating the spatial cross-correlation function between subsets of localized particles imaged at different times. Correction down to ~5 nm precision is achieved despite the fact that different molecules are imaged in each frame. We demonstrate the performance of our drift correction algorithm with different simulated structures and analyze its dependence on particle density and localization precision. By imaging mitochondria with Biplane FPALM we show our algorithm's feasibility in a practical application.

  5. Material Viscoelasticity-Induced Drift of Micro-Accelerometers.

    Science.gov (United States)

    Zhou, Wu; Peng, Peng; Yu, Huijun; Peng, Bei; He, Xiaoping

    2017-09-14

    Polymer-based materials are commonly used as an adhesion layer for bonding die chip and substrate in micro-system packaging. Their properties exhibit significant impact on the stability and reliability of micro-devices. The viscoelasticity, one of most important attributes of adhesive materials, is investigated for the first time in this paper to evaluate the long-term drift of micro-accelerometers. The accelerometer was modeled by a finite element (FE) method to emulate the structure deformation and stress development induced by change of adhesive property. Furthermore, the viscoelastic property of the adhesive was obtained by a series of stress-relaxation experiments using dynamic mechanical analysis (DMA). The DMA curve was imported into the FE model to predict the drift of micro-accelerometers over time and temperature. The prediction results verified by experiments showed that the accelerometer experienced output drift due to the development of packaging stress induced by both the thermal mismatch and viscoelastic behaviors of the adhesive. The accelerometers stored at room temperature displayed a continuous drift of zero offset and sensitivity because of the material viscoelasticity. Moreover, the drift level of accelerometers experiencing high temperature load was relatively higher than those of lower temperature in the same period.

  6. Drift-free MPEG-4 AVC semi-fragile watermarking

    Science.gov (United States)

    Hasnaoui, M.; Mitrea, M.

    2014-02-01

    While intra frame drifting is a concern for all types of MPEG-4 AVC compressed-domain video processing applications, it has a particular negative impact in watermarking. In order to avoid the drift drawbacks, two classes of solutions are currently considered in the literature. They try either to compensate the drift distortions at the expense of complex decoding/estimation algorithms or to restrict the insertion to the blocks which are not involved in the prediction, thus reducing the data payload. The present study follows a different approach. First, it algebraically models the drift distortion spread problem by considering the analytic expressions of the MPEG-4 AVC encoding operations. Secondly, it solves the underlying algebraic system under drift-free constraints. Finally, the advanced solution is adapted to take into account the watermarking peculiarities. The experiments consider an m-QIM semi-fragile watermarking method and a video surveillance corpus of 80 minutes. For prescribed data payload (100 bit/s), robustness (BER < 0.1 against transcoding at 50% in stream size), fragility (frame modification detection with accuracies of 1/81 from the frame size and 3s) and complexity constraints, the modified insertion results in gains in transparency of 2 dB in PSNR, of 0.4 in AAD, of 0.002 in IF, of 0.03 in SC, of 0.017 NCC and 22 in DVQ.

  7. Interception and retention of simulated cooling tower drift by vegetation

    International Nuclear Information System (INIS)

    Taylor, F.G. Jr.; Parr, P.D.

    1978-01-01

    A key issue concerning environmental impacts from cooling tower operation is the interception of drift by vegetation and the efficiency of plants in retaining the residue scavenged from the atmosphere. Chromated drift water, typical of the cooling towers of the Department of Energy's uranium enrichment facilities at Oak Ridge, Tennessee, was prepared using radio-labelled chromium. A portable aerosol generator was used to produce a spectrum of droplets with diameters (100 to 1300 μ) characteristic of cooling towers using state-of-the-art drift eliminators. Efficiency of interception by foliage varied according to leaf morphology with yellow poplar seedlings intercepting 72% of the deposition mass in contrast to 45% by loblolly pine and 24% by fescue grass. Retention patterns of intercepted deposition consisted of a short-time component (0 to 3 days) and a long-time component (3 to 63 days). Retention times, estimated from the regression equation of the long component, indicated that drift contamination from any deposition event may persist from between 8 and 12 weeks. In field situations adjacent to cooling towers, the average annual concentration of drift on vegetation at any distance remains relatively constant, with losses from weathering being compensated by chronic deposition

  8. Conformation and drift of a telechelic chain in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Aniket [Department of Physics, 4000 Central Florida Boulevard, University of Central Florida, Orlando, FL 32816-2385 (United States)

    2004-11-10

    The conformation and drift properties of a telechelic chain moving through a porous host of randomly distributed static obstacles are studied using Brownian dynamics simulation for a Grest-Kremer bead-spring model of polymer. Static chain conformations exhibit non-monotonic behaviour as a function of the impurity density {rho}{sub imp} at zero bias. The chain initially shrinks due to an entropic barrier as the density of the obstacles {rho}{sub imp} is increased. In the presence of the obstacles it requires only a tiny bias for a long chain to be mostly stretched. We then study the drift property of the chain as a function of the bias and impurity density. The drift velocity of the chain saturates beyond a threshold bias F{sub x}{sup crit}. This observation can be useful in designing DNA sequencing methods based on electrophoretic mobility.

  9. Drift Wave Test Particle Transport in Reversed Shear Profile

    International Nuclear Information System (INIS)

    Horton, W.; Park, H.B.; Kwon, J.M.; Stronzzi, D.; Morrison, P.J.; Choi, D.I.

    1998-01-01

    Drift wave maps, area preserving maps that describe the motion of charged particles in drift waves, are derived. The maps allow the integration of particle orbits on the long time scale needed to describe transport. Calculations using the drift wave maps show that dramatic improvement in the particle confinement, in the presence of a given level and spectrum of E x B turbulence, can occur for q(r)-profiles with reversed shear. A similar reduction in the transport, i.e. one that is independent of the turbulence, is observed in the presence of an equilibrium radial electric field with shear. The transport reduction, caused by the combined effects of radial electric field shear and both monotonic and reversed shear magnetic q-profiles, is also investigated

  10. Effect of solenoidal magnetic field on drifting laser plasma

    Science.gov (United States)

    Takahashi, Kazumasa; Okamura, Masahiro; Sekine, Megumi; Cushing, Eric; Jandovitz, Peter

    2013-04-01

    An ion source for accelerators requires to provide a stable waveform with a certain pulse length appropriate to the application. The pulse length of laser ion source is easy to control because it is expected to be proportional to plasma drifting distance. However, current density decay is proportional to the cube of the drifting distance, so large current loss will occur under unconfined drift. We investigated the stability and current decay of a Nd:YAG laser generated copper plasma confined by a solenoidal field using a Faraday cup to measure the current waveform. It was found that the plasma was unstable at certain magnetic field strengths, so a baffle was introduced to limit the plasma diameter at injection and improve the stability. Magnetic field, solenoid length, and plasma diameter were varied in order to find the conditions that minimize current decay and maximize stability.

  11. Thirty-five years of drift-tube linac experience

    International Nuclear Information System (INIS)

    Knowles, H.B.

    1984-10-01

    The history of the drift-tube linear accelerator (linac) for the first 35 years of its existence is briefly reviewed. Both US and foreign experience is included. Particular attention is given to technological improvements, operational reliability, capital investment, and number of personnel committed to drift-tube linac (DTL) development. Preliminary data indicate that second- and third-generation (post-1960) DTLs have, in the US alone, operated for a combined total period of more than 75 machine-years and that very high reliability (>90%) has been achieved. Existing US drift-tube linacs represent a capital investment of at least $250 million (1983). Additional statistical evidence, derived from the proceedings of the last 11 linear accelerator conferences, supports the view that the DTL has achieved a mature technological base. The report concludes with a discussion of important recent advances in technology and their applications to the fourth generation of DTLs, many of which are now becoming operational

  12. Behaviour of large cylindrical drift chambers in a superconducting solenoid

    International Nuclear Information System (INIS)

    Boer, W. de; Fues, W.; Grindhammer, G.; Kotthaus, R.; Lierl, H.; Moss, L.

    1980-04-01

    We describe the construction and behaviour of a set of cylindrical drift chambers operating inside a superconducting solenoid with a central magnetic field of 1.3 T. The chambers are part of the 4 π detector CELLO at the e + e - storage ring PETRA in Hamburg. The chambers were designed without field shaping to keep them as simple as possible. In order to parametrize accurately the nonlinear space-time relation, we used a computer simulation of the drift process in inhomogenous electric and magnetic fields. With such a parametrization we achieved a resolution of 210 μm, averaged over the whole drift cell and angles of incidence up to 30 0 . (orig.)

  13. Image processing for drift compensation in fluorescence microscopy

    DEFF Research Database (Denmark)

    Petersen, Steffen; Thiagarajan, Viruthachalam; Coutinho, Isabel

    2013-01-01

    Fluorescence microscopy is characterized by low background noise, thus a fluorescent object appears as an area of high signal/noise. Thermal gradients may result in apparent motion of the object, leading to a blurred image. Here, we have developed an image processing methodology that may remove....../reduce blur significantly for any type of microscopy. A total of ~100 images were acquired with a pixel size of 30 nm. The acquisition time for each image was approximately 1second. We can quantity the drift in X and Y using the sub pixel accuracy computed centroid location of an image object in each frame....... We can measure drifts down to approximately 10 nm in size and a drift-compensated image can therefore be reconstructed on a grid of the same size using the “Shift and Add” approach leading to an image of identical size asthe individual image. We have also reconstructed the image using a 3 fold larger...

  14. Precipitates/Salts Model Calculations for Various Drift Temperature Environments

    International Nuclear Information System (INIS)

    Marnier, P.

    2001-01-01

    The objective and scope of this calculation is to assist Performance Assessment Operations and the Engineered Barrier System (EBS) Department in modeling the geochemical effects of evaporation within a repository drift. This work is developed and documented using procedure AP-3.12Q, Calculations, in support of ''Technical Work Plan For Engineered Barrier System Department Modeling and Testing FY 02 Work Activities'' (BSC 2001a). The primary objective of this calculation is to predict the effects of evaporation on the abstracted water compositions established in ''EBS Incoming Water and Gas Composition Abstraction Calculations for Different Drift Temperature Environments'' (BSC 2001c). A secondary objective is to predict evaporation effects on observed Yucca Mountain waters for subsequent cement interaction calculations (BSC 2001d). The Precipitates/Salts model is documented in an Analysis/Model Report (AMR), ''In-Drift Precipitates/Salts Analysis'' (BSC 2001b)

  15. On the Theory of Compensation in Lithium drifted Semiconductor Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lauber, A.

    1969-04-15

    The lithium ion drift method produces detectors with a highly but not perfectly compensated intrinsic region. The amount of fixed space charge left in the depleted layer and its dependence on drift and clean-up parameters is of great practical interest. The imperfect compensation is mainly due to the presence in the depletion layer of thermally generated electron-hole pairs swept apart by the voltage applied to the detector during drift. A theoretical model is developed which takes into account the influence on the fixed space charge of mobile carrier generation and recombination. When recombination of free electrons and holes is negligible the theory predicts the formation of linear space charge gradients. When recombination is strong a constant space charge throughout a large part of the compensated layer may result. The theoretical calculations are compared with experimental findings. The influence of space charge on detector performance is discussed.

  16. Dφ vertex drift chamber construction and test results

    International Nuclear Information System (INIS)

    Clark, A.R.; Goozen, F.; Grudberg, P.; Klopfenstein, C.; Kerth, L.T.; Loken, S.C.; Oltman, E.; Strovink, M.; Trippe, T.G.

    1991-05-01

    A jet-cell based vertex chamber has been built for the D OE experiment at Fermilab and operated in a test beam there. Low drift velocity and diffusion properties were achieved using CO 2 (95%)-ethane(5%) at atmospheric pressure. The drift velocity is found to be consistent with [9.74+8.68(|E|-1.25)] μm/nsec where E is the electric field strength in (kV/cm < |E| z 1.6 kV/cm.) An intrinsic spatial resolution of 60 μm or better for drift distances greater than 2 mm is measured. The track pair efficiency is estimated to be better than 90% for separations greater than 630 μm. 8 refs., 6 figs., 1 tab

  17. Perturbed GUE Minor Process and Warren's Process with Drifts

    Science.gov (United States)

    Ferrari, Patrik L.; Frings, René

    2014-01-01

    We consider the minor process of (Hermitian) matrix diffusions with constant diagonal drifts. At any given time, this process is determinantal and we provide an explicit expression for its correlation kernel. This is a measure on the Gelfand-Tsetlin pattern that also appears in a generalization of Warren's process (Electron. J. Probab. 12:573-590, 2007), in which Brownian motions have level-dependent drifts. Finally, we show that this process arises in a diffusion scaling limit from an interacting particle system in the anisotropic KPZ class in 2+1 dimensions introduced in Borodin and Ferrari (Commun. Math. Phys., 2008). Our results generalize the known results for the zero drift situation.

  18. Genetic diversity of natural Tunisian Lavandula multifida L ...

    African Journals Online (AJOL)

    The populations from the lower semi-arid bioclimate showed relatively higher polymorphism. A high genetic differentiation among all populations and a limited gene flow at all space scales were detected as a result of habitat fragmentation, low size of populations and genetic drift. However, the level of differentiation among ...

  19. Spray drift reduction techniques for vineyards in fragmented landscapes.

    Science.gov (United States)

    Otto, S; Loddo, D; Baldoin, C; Zanin, G

    2015-10-01

    In intensive agricultural systems spray drift is one of the major potential diffuse pollution pathways for pesticides and poses a risk to the environment. There is also increasing concern about potential exposure to bystanders and passers-by, especially in fragmented landscapes like the Italian pre-Alps, where orchards and vineyards are surrounded by residential houses. There is thus an urgent need to do field measurements of drift generated by air-blast sprayer in vineyards, and to develop measures for its reduction (mitigation). A field experiment with an "event method" was conducted in north-eastern Italy in no-wind conditions, in the hilly area famed for Prosecco wine production, using an air-blast sprayer in order to evaluate the potential spray drift from equipment and the effectiveness of some practical mitigation measures, either single or in combination. A definition of mitigation is proposed, and a method for the calculation of total effectiveness of a series of mitigation measures is applied to some what-if scenarios of interest. Results show that low-drift equipment reduced potential spray drift by 38% and that a fully developed vine curtain mitigated it by about 70%; when the last row was treated without air-assistance mitigation was about 74%; hedgerows were always very effective in providing mitigation of up to 98%. In conclusion, spray drift is not inevitable and can be markedly reduced using a few mitigation measures, most already available to farmers, that can be strongly recommended for environmental regulatory schemes and community-based participatory research. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. A 55 cm{sup 2} cylindrical silicon drift detector

    Energy Technology Data Exchange (ETDEWEB)

    Holl, P. [Brookhaven National Lab., Upton, NY (United States); Rehak, P. [Brookhaven National Lab., Upton, NY (United States); Ceretto, F. [Max-Planck-Institute for Nuclear Physics, Heidelberg (Germany); Faschingbauer, U. [Max-Planck-Institute for Nuclear Physics, Heidelberg (Germany); Wurm, J.P. [Max-Planck-Institute for Nuclear Physics, Heidelberg (Germany); Castoldi, A. [Universita degli Studi di Milano, Departimento di Fisica, Via Celoria 16, 20133 Milano (Italy); Gatti, E. [Politecnico di Milano, Piazza L. da Vinci, I-20133 Milano (Italy)

    1996-08-01

    AZTEC, a large area cylindrical silicon drift detector was designed, produced and tested. AZTEC will be the building block of the NA45 and WA98 micro vertex detectors at CERN. Two AZTEC detectors are placed down stream from the target to measure trajectories of charged particles produced in the forward direction. The active area of AZTEC is practically the full usable surface of a 100 mm diameter wafer. The electrons drift radially from the center towards the outside. The sensing anodes are located at a radius of 42 mm. The center of the wafer is cut out and forms a passage for the noninteracting beam. With a minimal radius for this hole the active region of the drift detector starts at an inner radius of 3.1 mm. Any larger radius can be selected if necessary. With this geometry and a typical operating voltage the maximum drift time is less than 4 {mu}s. Due to constrains in the mask layout the readout region and field electrodes are designed along the 360 sides of a symmetric polygon. All structures on one surface of the wafer are rotated by 0.5 with respect to the other surface. In the middle plane of the detector, where the electrons are mostly transported, the effective geometry is close to a smoothed polygon with 720 sides, cancelling practically all effects of the non-perfect cylindrical symmetry. The radial position of fast charged particles is measured by the electron drift time within the detector. The drift velocity can be monitored by 48 injection points at three different radii. The azimuthal angle is measured by the 360 readout anodes. Each anode is subdivided into five segments, which are interlaced with the neighbouring anodes. By this methode the azimuthal resolution is improved and corresponds to a 720 channel read out. (orig.).

  1. Studies of electron drift velocity in nitrogen and isobutane

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Pontificia Univ. Catolica de Sao Paulo (PUC/SP), SP (Brazil); Vivaldini, Tulio C.; Lima, Iara B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Ridenti, Marco A.; Pascholati, Paulo R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica. Lab. do Acelerador Linear; Fonte, Paulo; Mangiarotti, Alessio [Universidade de Coimbra (Portugal). Dept. de fisica. Lab. de Instrumentacao e Fisica Experimental de Particulas

    2009-07-01

    Full text: The electron drift velocity is one of the most important transport parameters used to describe the physical behaviour of gas discharges and the development of avalanches in gaseous detectors, mainly when temporal information is significant, as in drift chambers and in the recent Resistive Plate Chambers (RPCs). Although many filling gases, isobutane is frequently used in RPCs, due to its excellent timing properties, but at high electric fields conditions there are insufficient data available in literature. In the present work we report the preliminary results related to the dependence of the electron drift velocity for isobutane as function of the reduced electric field E/N, in the range of 100 Td up to 216 Td. There are different methods to determine electron drift velocity in a gas, and our measurements were based on the Pulsed Townsend technique, which consists of extracting electrons from a metallic cathode and accelerates them toward the anode by a uniform electric field. Once the drift distance and the transit time are known, the drift velocities can be determined. In our system, the incidence of a nitrogen laser beam (LTB MNL200-LD) liberates electron from the cathode made of aluminium (40mm diameter). By means of a high voltage supply (Bertan, 225-30), these electrons are accelerated toward the anode (made of a high resistivity glass - 2:10{sup 12}{omega} cm) and this movement produces a fast electric signal in the anode, which is digitalized in an oscilloscope (LeCroy WavePro 7000) with 1 GHz bandwidth and 10 GS/s. The values obtained were compared to that ones of a Bolsig+ simulation code. In order to validate the technique and to analyze non-uniformity effects, results for nitrogen are also presented. (author)

  2. Studies of electron drift velocity in nitrogen and isobutane

    International Nuclear Information System (INIS)

    Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B.; Vivaldini, Tulio C.; Lima, Iara B.; Ridenti, Marco A.; Pascholati, Paulo R.; Fonte, Paulo; Mangiarotti, Alessio

    2009-01-01

    Full text: The electron drift velocity is one of the most important transport parameters used to describe the physical behaviour of gas discharges and the development of avalanches in gaseous detectors, mainly when temporal information is significant, as in drift chambers and in the recent Resistive Plate Chambers (RPCs). Although many filling gases, isobutane is frequently used in RPCs, due to its excellent timing properties, but at high electric fields conditions there are insufficient data available in literature. In the present work we report the preliminary results related to the dependence of the electron drift velocity for isobutane as function of the reduced electric field E/N, in the range of 100 Td up to 216 Td. There are different methods to determine electron drift velocity in a gas, and our measurements were based on the Pulsed Townsend technique, which consists of extracting electrons from a metallic cathode and accelerates them toward the anode by a uniform electric field. Once the drift distance and the transit time are known, the drift velocities can be determined. In our system, the incidence of a nitrogen laser beam (LTB MNL200-LD) liberates electron from the cathode made of aluminium (40mm diameter). By means of a high voltage supply (Bertan, 225-30), these electrons are accelerated toward the anode (made of a high resistivity glass - 2:10 12 Ω cm) and this movement produces a fast electric signal in the anode, which is digitalized in an oscilloscope (LeCroy WavePro 7000) with 1 GHz bandwidth and 10 GS/s. The values obtained were compared to that ones of a Bolsig+ simulation code. In order to validate the technique and to analyze non-uniformity effects, results for nitrogen are also presented. (author)

  3. Amplifying the helicopter drift in a conformal HMD

    Science.gov (United States)

    Schmerwitz, Sven; Knabl, Patrizia M.; Lueken, Thomas; Doehler, Hans-Ullrich

    2016-05-01

    Helicopter operations require a well-controlled and minimal lateral drift shortly before ground contact. Any lateral speed exceeding this small threshold can cause a dangerous momentum around the roll axis, which may cause a total roll over of the helicopter. As long as pilots can observe visual cues from the ground, they are able to easily control the helicopter drift. But whenever natural vision is reduced or even obscured, e.g. due to night, fog, or dust, this controllability diminishes. Therefore helicopter operators could benefit from some type of "drift indication" that mitigates the influence of a degraded visual environment. Generally humans derive ego motion by the perceived environmental object flow. The visual cues perceived are located close to the helicopter, therefore even small movements can be recognized. This fact was used to investigate a modified drift indication. To enhance the perception of ego motion in a conformal HMD symbol set the measured movement was used to generate a pattern motion in the forward field of view close or on the landing pad. The paper will discuss the method of amplified ego motion drift indication. Aspects concerning impact factors like visualization type, location, gain and more will be addressed. Further conclusions from previous studies, a high fidelity experiment and a part task experiment, will be provided. A part task study will be presented that compared different amplified drift indications against a predictor. 24 participants, 15 holding a fixed wing license and 4 helicopter pilots, had to perform a dual task on a virtual reality headset. A simplified control model was used to steer a "helicopter" down to a landing pad while acknowledging randomly placed characters.

  4. A quasilinear operator retaining magnetic drift effects in tokamak geometry

    Science.gov (United States)

    Catto, Peter J.; Lee, Jungpyo; Ram, Abhay K.

    2017-12-01

    The interaction of radio frequency waves with charged particles in a magnetized plasma is usually described by the quasilinear operator that was originally formulated by Kennel & Engelmann (Phys. Fluids, vol. 9, 1966, pp. 2377-2388). In their formulation the plasma is assumed to be homogenous and embedded in a uniform magnetic field. In tokamak plasmas the Kennel-Engelmann operator does not capture the magnetic drifts of the particles that are inherent to the non-uniform magnetic field. To overcome this deficiency a combined drift and gyrokinetic derivation is employed to derive the quasilinear operator for radio frequency heating and current drive in a tokamak with magnetic drifts retained. The derivation requires retaining the magnetic moment to higher order in both the unperturbed and perturbed kinetic equations. The formal prescription for determining the perturbed distribution function then follows a novel procedure in which two non-resonant terms must be evaluated explicitly. The systematic analysis leads to a diffusion equation that is compact and completely expressed in terms of the drift kinetic variables. The equation is not transit averaged, and satisfies the entropy principle, while retaining the full poloidal angle variation without resorting to Fourier decomposition. As the diffusion equation is in physical variables, it can be implemented in any computational code. In the Kennel-Engelmann formalism, the wave-particle resonant delta function is either for the Landau resonance or the Doppler shifted cyclotron resonance. In the combined gyro and drift kinetic approach, a term related to the magnetic drift modifies the resonance condition.

  5. Lagrangians for plasmas in drift-fluid approximation

    International Nuclear Information System (INIS)

    Pfirsch, D.; Correa-Restrepo, D.

    1996-10-01

    For drift waves and related instabilities conservation laws can play a crucial role. In an ideal theory these conservation laws are guaranteed when a Lagrangian can be found from which the equations for the various quantities result by Hamilton's principle. Such a Lagrangian for plasmas in drift-fluid approximation was obtained by a heuristic method in a recent paper by Pfirsch and Correa-Restrepo. In the present paper the same Lagrangian is derived from the exact multi-fluid Lagrangian via an iterative approximation procedure which resembles the standard method usually applied to the equations of motion. That method, however, does not guarantee all the conservation laws to hold. (orig.)

  6. Drift Chambers Simulations in BM@N Experiment

    Directory of Open Access Journals (Sweden)

    Fedorišin Ján

    2016-01-01

    Full Text Available Drift chambers constitute an important part of the tracking system of the BM@N experiment designed to study the production of baryonic matter at the Nuclotron energies. GEANT programming package is employed to investigate the drift chamber response to particles produced in relativistic nuclear collisions of C+C nuclei, which are simulated by the UrQMD and LAQGSM Monte Carlo generators. These simulations are combined with the first BM@N experimental data to estimate particle track coordinates and their errors.

  7. The effect of plasma drift on the electromagnetic cyclotron instability

    International Nuclear Information System (INIS)

    Kulkarni, V.H.; Rycroft, M.J.

    1979-01-01

    It is shown that the drift of plasma across a homogeneous magnetic field causes the generation of a wave electric field which, for waves propagating along the magnetic field in the whistler mode, is in the direction of the magnetic field. This leads to Landau damping of the wave field by the background electron distribution, simultaneously with amplification via the electromagnetic cyclotron instability. The drift velocity of the plasma for zero net growth of a whistler mode signal is calculated. It is suggested that such a process occurs in the equatorial region of the magnetosphere during a geomagnetic storm and accounts for the missing band of emissions at half the equatorial gyrofrequency. (Auth.)

  8. Slow Drift-Oscillations of a Ship in Irregular Waves

    Directory of Open Access Journals (Sweden)

    Odd M. Faltinsen

    1980-10-01

    Full Text Available A procedure to calculate horizontal slow drift excitation forces on an infinitely long horizontal cylinder in irregular beam sea waves is presented. The hydrodynamic boundary-value problem is solved correctly to second order in wave amplitude. Results in the form of second order transfer functions are presented for different, two-dimensional shapes. It is concluded that Newman's approximative method is a practical way to calculate slow drift excitation forces on a ship in beam sea and it is suggested that it may be used in a more general case. Applications of the results for moored ships are discussed.

  9. Lagrangians for plasmas in the drift-fluid approximation

    Energy Technology Data Exchange (ETDEWEB)

    Pfirsch, Dieter; Corres-Restrepo, Dario [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

    1997-04-01

    For drift waves and related instabilities, conservation laws can play a crucial role. In an ideal theory these conservation laws are guaranteed when a Lagrangian can be found from which the equations for the various quantities result by Hamilton`s principle. Such a Lagrangian for plasmas in the drift-fluid approximation was obtained by a heuristic method in a recent paper by Pfirsch and Correa-Restrepo. In the present paper the same Lagrangian is derived from the exact multifluid Lagrangian via an iterative approximation procedure which resembles the standard method usually applied to the equations of motion. That method, however, does not guarantee that all the conservation laws hold. (author).

  10. Rippling and drift instabilities in the straight cylinder tokamak

    International Nuclear Information System (INIS)

    Rogister, A.

    1984-01-01

    It is shown that the electron and ion diamagnetic drifts stabilize the rippling mode in the straigth cylindrical tokamak model. Parallel electron heat conduction is further stabilizing if the parameter etasub(e) = dlnTsub(e)/dlnN is positive. This has a consequence that the mode does not survive at temperatures exceeding, typically, 50 eV for standard values of magnetic field and density. The collisional drift wave is found to be always stable even when the effect of the tokamak current is included in the calculation. (orig.)

  11. Drift Kelvin-Helmholtz instabilities in space plasmas

    Science.gov (United States)

    Sharma, Avadhesh C.; Srivastava, Krishna M.

    1992-01-01

    Drift Kelvin-Helmholtz instabilities of a finite-beta plasma in equilibrium electric and magnetic fields which are perpendicular to each other are studied using two fluid equations. Three types of these instabilities are considered including the magnetosonic instability of a finite beta-homogeneous plasma, the electrostatic drift instability of an inhomogeneous low-beta plasma, and the magneto-acoustic instability of a high-beta inhomogeneous isothermal plasma. It is shown that the electric field has either stabilizing or destabilizing effect depending on conditions under consideration.

  12. Annals of the international geophysical year ionospheric drift observations

    CERN Document Server

    Rawer, K; Beloussov, V V; Beynon, W J G

    2013-01-01

    Annals of the International Geophysical Year, Volume 33: Results of Ionospheric Drift Observations describes the systematic changes in individual ionospheric observations during the International Geophysical Year (IGY). This book is composed of four chapters, and begins with a presentation of the general data on stations and the lists of publications concerning drift work during IGY/IGC. The next chapter contains the results obtained mainly by intercomparison of the time shift between fadings observed on three antenna separated by a distance of roughly a wavelength. These data are followed by

  13. Drift chamber and pulse height readout systems using analog multiplexing

    International Nuclear Information System (INIS)

    Cisneros, E.L; Kang, H.K.; Hall, J.N.; Larsen, R.S.

    1976-11-01

    Drift chamber and pulse-height readout systems are being developed for use in a new large scale detector at the SPEAR colliding beam facility. The systems are based upon 32 channels of sample-and-hold together with an analog multiplexer in a single-width CAMAC module. The modules within each crate are scanned by an autonomous controller containing a single ADC and memory plus arithmetic capability for offset, gain and linearity corrections. The drift chamber module has a facility for extracting hit wire information for use in trigger decision circuitry

  14. Organic Scintillator Detector Response Simulations with DRiFT

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Madison Theresa [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bates, Cameron Russell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mckigney, Edward Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pinilla, Maria Isabel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Solomon, Jr., Clell Jeffrey [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sood, Avneet [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-12-19

    Accurate detector modeling is a requirement to design systems in many non-proliferation scenarios; by determining a Detector’s Response Function (DRF) to incident radiation, it is possible characterize measurements of unknown sources. DRiFT is intended to post-process MCNP® output and create realistic detector spectra. Capabilities currently under development include the simulation of semiconductor, gas, and (as is discussed in this work) scintillator detector physics. Energy spectra and pulse shape discrimination (PSD) trends for incident photon and neutron radiation have been reproduced by DRiFT.

  15. A Simple Stochastic Differential Equation with Discontinuous Drift

    DEFF Research Database (Denmark)

    Simonsen, Maria; Leth, John-Josef; Schiøler, Henrik

    2013-01-01

    In this paper we study solutions to stochastic differential equations (SDEs) with discontinuous drift. We apply two approaches: The Euler-Maruyama method and the Fokker-Planck equation and show that a candidate density function based on the Euler-Maruyama method approximates a candidate density...... function based on the stationary Fokker-Planck equation. Furthermore, we introduce a smooth function which approximates the discontinuous drift and apply the Euler-Maruyama method and the Fokker-Planck equation with this input. The point of departure for this work is a particular SDE with discontinuous...

  16. Electron drift velocity in argon-methane mixture

    International Nuclear Information System (INIS)

    Hakeem, N.El; Mathieson, E.

    1978-01-01

    Described are the results of a series of measurements of electron drift velocity taken with samples of chemically pure grade gas mixture of Ar-10% CH 4 (N 2 2 2 2 O<2 ppm). The measured drift velocity is plotted as a function of the ratio of electric field to pressure in the range from 0.05 to 0.8 V/cmxtorr. The measurements are reproducible only to within 4%. The results of numerical calculations employing the well-established argon elastic and methane elastic and inelastic cross sections are also included. The disagreement from the present experimental results, and from those obtained elsewhere, is rather puzzling

  17. Assembly of Drift Tubes (DT) Chambers at CIEMAT (Madrid)

    CERN Multimedia

    Jesus Puerta-Pelayo

    2003-01-01

    The construction of muon drift tube chambers (DT) has been carried out in four different european institutes: Aachen (Germany), CIEMAT-Madrid (Spain), Legnaro and Turin (Italy), all of them following similar procedures and quality tests. Each chamber is composed by three or two independent units called superlayers, with four layers of staggered drift cells each. The assembly of a superlayer is a succesive glueing of aluminium plates and I-beams with electrodes previously attached, forming a rectangular and gas-tight volume. These pictures illustrate the various processes of material preparation, construction, equipment and assembly of full chambers at CIEMAT (Madrid).

  18. Nonlinear evolution of the lower-hybrid drift instability

    International Nuclear Information System (INIS)

    Brackbill, J.U.; Forslund, D.W.; Quest, K.B.; Winske, D.

    1984-01-01

    The results of simulations of the lower-hybrid drift instability in a neutral sheet configuration are described. The simulations use an implicit formulation to relax the usual time step limitations and thus extend previous explicit calculations to weaker gradients, larger mass ratios, and long times compared with the linear growth time. The numerical results give the scaling of the saturation level, heating rates, resistivity, and cross-field diffusion and a demonstration by comparison with a fluid electron model that dissipation in the lower-hybrid drift instability is caused by electron kinetic effects

  19. Particle simulation of drift waves in a sheared magnetic field

    International Nuclear Information System (INIS)

    Sydora, R.D.; Leboeuf, J.N.; Tajima, T.

    1983-11-01

    Electrostatic properties of density gradient drift waves (the universal mode), in a sheared magnetic field, are studied using a two-and-one-half dimensional particle code. For the case of a single rational surface, the drift waves are found to be stable with an eigenmode structure that matches the linear theoretical prediction as long as the ion resonance point is well within the system. This applies to both even and odd parity modes with respect to the rational surface. The dependence on various parameters such as the shear length is examined

  20. Disentangling plastic and genetic changes in body mass of Siberian jays

    NARCIS (Netherlands)

    Gienapp, P.; Merilä, J.

    2014-01-01

    Spatial and temporal phenotypic differentiation in mean body size is of commonplace occurrence, but the underlying causes remain often unclear: both genetic differentiation in response to selection (or drift) and environmentally induced plasticity can create similar phenotypic patterns. Studying

  1. Conservation genetics in transition to conservation genomics

    DEFF Research Database (Denmark)

    Ouborg, N. Joop; Pertoldi, Cino; Loeschcke, Volker

    2010-01-01

    in conservation biology. This has allowed assessment of the impact of genetic drift on genetic variation, of the level of inbreeding within populations, and of the amount of gene flow between or within populations. Recent developments in genomic techniques, including next generation sequencing, whole genome scans...... and gene-expression pattern analysis, have made it possible to step up from a limited number of neutral markers to genome-wide estimates of functional genetic variation. Here, we focus on how the transition of conservation genetics to conservation genomics leads to insights into the dynamics of selectively...

  2. Alfred Wegener-From Continental Drift to Plate Tectonics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 6. Alfred Wegener – From Continental Drift to Plate Tectonics. A J Saigeetha Ravinder Kumar Banyal. General Article Volume 10 Issue 6 June 2005 pp 43-59. Fulltext. Click here to view fulltext PDF. Permanent link:

  3. Correction of Dopant Concentration Fluctuation Effects in Silicon Drift Detectors

    CERN Document Server

    Nouais, D; Bonvicini, V; Cerello, P G; Crescio, E; Giubellino, P; Hernández-Montoya, R; Kolojvari, A A; Montaño-Zetina, L M; Nilsen, B S; Piemonte, C; Rachevsky, A; Tosello, F; Vacchi, A; Wheadon, R

    2001-01-01

    Dopant fluctuations in silicon wafers are responsible for systematic errors in the determination of the particle crossing point in silicon drift detectors. In this paper, we report on the first large scale measurement of this effect by means of a particle beam. A significant improvement of the anodic resolution has been obtained by correcting for these systematic deviations.

  4. Parametric excitation of drift waves in a sheared slab geometry

    International Nuclear Information System (INIS)

    Vranjes, J.; Weiland, J.

    1992-01-01

    The threshold for parametric excitation of drift waves in a sheared slab geometry is calculated for a pump wave that is a standing wave along the magnetic field, using the Hasegawa-Mima nonlinearity. The shear damping is counteracted by the parametric coupling and the eigenvalue problem is solved analytically using Taylor's strong coupling approximation. (au)

  5. Consistent measurements comparing the drift features of noble gas mixtures

    CERN Document Server

    Becker, U; Fortunato, E M; Kirchner, J; Rosera, K; Uchida, Y

    1999-01-01

    We present a consistent set of measurements of electron drift velocities and Lorentz deflection angles for all noble gases with methane and ethane as quenchers in magnetic fields up to 0.8 T. Empirical descriptions are also presented. Details on the World Wide Web allow for guided design and optimization of future detectors.

  6. Consistent measurements comparing the drift features of noble gas mixtures

    International Nuclear Information System (INIS)

    Becker, U.; Dinner, R.; Fortunato, E.; Kirchner, J.; Rosera, K.; Uchida, Y.

    1999-01-01

    We present a consistent set of measurements of electron drift velocities and Lorentz deflection angles for all noble gases with methane and ethane as quenchers in magnetic fields up to 0.8 T. Empirical descriptions are also presented. Details on the World Wide Web allow for guided design and optimization of future detectors

  7. Analysis of the SPS Long Term Orbit Drifts

    Energy Technology Data Exchange (ETDEWEB)

    Velotti, Francesco [CERN; Bracco, Chiara [CERN; Cornelis, Karel [CERN; Drøsdal, Lene [CERN; Fraser, Matthew [CERN; Gianfelice-Wendt, Eliana [Fermilab; Goddard, Brennan [CERN; Kain, Verena [CERN; Meddahi, Malika [CERN

    2016-06-01

    The Super Proton Synchrotron (SPS) is the last accelerator in the Large Hadron Collider (LHC) injector chain, and has to deliver the two high-intensity 450 GeV proton beams to the LHC. The transport from SPS to LHC is done through the two Transfer Lines (TL), TI2 and TI8, for Beam 1 (B1) and Beam 2 (B2) respectively. During the first LHC operation period Run 1, a long term drift of the SPS orbit was observed, causing changes in the LHC injection due to the resulting changes in the TL trajectories. This translated into longer LHC turnaround because of the necessity to periodically correct the TL trajectories in order to preserve the beam quality at injection into the LHC. Different sources for the SPS orbit drifts have been investigated: each of them can account only partially for the total orbit drift observed. In this paper, the possible sources of such drift are described, together with the simulated and measured effect they cause. Possible solutions and countermeasures are also discussed.

  8. Frank Bursley Taylor - Forgotten Pioneer of Continental Drift.

    Science.gov (United States)

    Black, George W., Jr.

    1979-01-01

    Frank B. Taylor was an American geologist who specialized in the glacial geology of the Great Lakes. This article discusses his work on the Continental Drift theory, which preceeded the work of Alfred Wegener by a year and a half. (MA)

  9. Drift effects on the galactic cosmic ray modulation

    Energy Technology Data Exchange (ETDEWEB)

    Laurenza, M.; Storini, M. [INAF/IAPS, Via Fosso del Cavaliere 100, I-00133 Roma (Italy); Vecchio, A. [Istituto Nazionale di Geofisica e Vulcanologia-Sede di Cosenza, I-87036 Rende (CS) (Italy); Carbone, V., E-mail: monica.laurenza@iaps.inaf.it [Dipartimento di Fisica, Università della Calabria, I-87036 Rende (CS) (Italy)

    2014-02-01

    Cosmic ray (CR) modulation is driven by both solar activity and drift effects in the heliosphere, although their role is only qualitatively understood as it is difficult to connect the CR variations to their sources. In order to address this problem, the Empirical Mode Decomposition technique has been applied to the CR intensity, recorded by three neutron monitors at different rigidities (Climax, Rome, and Huancayo-Haleakala (HH)), the sunspot area, as a proxy for solar activity, the heliospheric magnetic field magnitude, directly related to CR propagation, and the tilt angle (TA) of the heliospheric current sheet (HCS), which characterizes drift effects on CRs. A prominent periodicity at ∼six years is detected in all the analyzed CR data sets and it is found to be highly correlated with changes in the HCS inclination at the same timescale. In addition, this variation is found to be responsible for the main features of the CR modulation during periods of low solar activity, such as the flat (peaked) maximum in even (odd) solar cycles. The contribution of the drift effects to the global Galactic CR modulation has been estimated to be between 30% and 35%, depending on the CR particle energy. Nevertheless, the importance of the drift contribution is generally reduced in periods nearing the sunspot maximum. Finally, threshold values of ∼40°, ∼45°, and >55° have been derived for the TA, critical for the CR modulation at the Climax, Rome, and HH rigidity thresholds, respectively.

  10. Construction of a drift chamber prototype for the CMS experiment

    International Nuclear Information System (INIS)

    Berdugo, J.; Cerrada, M.; Daniel, M.; Martin, F.; Mocholi, J.; Romero, L.

    1997-01-01

    General design features of a small size drift chamber prototype are described in this report. Prototype construction has taken place at CIEMAT and we explain in detail the assembly procedure. This activity is part of a long term project to mass produce chambers for the muon barrel detector of the CMS experiment which will be installed at CERN. (Author)

  11. Assessing off-taraget impacts of herbicide drift on plants

    Science.gov (United States)

    Plants and plant communities provide vital economic services including production of food and fiber crops for direct human consumption and ecosystem services including wildlife habitat and cycling of nutrients and energy. These services can be impacted if herbicides drift from t...

  12. A cylindrical drift chamber with azimuthal and axial position readout

    Energy Technology Data Exchange (ETDEWEB)

    Bar-Yam, Z.; Cummings, J.P.; Dowd, J.P.; Eugenio, P.; Hayek, M.; Kern, W.; King, E.; Shenhav, N.; Chung, S.U.; Hackenburg, R.W.; Olchanski, C.; Weygand, D.P.; Willutzki, H.J.; Brabson, B.B.; Crittenden, R.R.; Dzierba, A.R.; Gunter, J.; Lindenbusch, R.; Rust, D.R.; Scott, E.; Smith, P.T.; Sulanke, T.; Teige, S.; Denisov, S.; Dushkin, A.; Kochetkov, V.; Lipaev, V.; Popov, A.; Shein, I.; Soldatov, A.; Anoshina, E.V.; Bodyagin, V.A.; Demianov, A.I.; Gribushin, A.M.; Kodolova, O.L.; Korotkikh, V.L.; Kostin, M.A.; Ostrovidov, A.I.; Sarycheva, L.I.; Sinev, N.B.; Vardanyan, I.N.; Yershov, A.A.; Adams, T.; Bishop, J.M.; Cason, N.M.; Sanjari, A.H.; LoSecco, J.M.; Manak, J.J.; Shephard, W.D.; Stienike, D.L.; Taegar, S.A.; Thompson, D.R.; Brown, D.S.; Pedlar, T.; Seth, K.K.; Wise, J.; Zhao, D.; Adams, G.S.; Napolitano, J.; Nozar, M.; Smith, J.A.; Witkowski, M. [Massachusetts Univ., North Dartmouth, MA (United States)]|[Brookhaven National Laboratory, Upton, L.I., NY 11973 (United States)]|[Indiana University, Bloomington, IN 47405 (United States)]|[Institute for High Energy Physics, Protvino (Russian Federation)]|[Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation)]|[University of Notre Dame, Notre Dame, IN 46556 (United States)]|[Northwestern University, Evanston, IL 60208 (United States)]|[Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    1997-02-21

    A cylindrical multiwire drift chamber with axial charge-division has been constructed and used in experiment E852 at Brookhaven National Laboratory. It serves as a trigger element and as a tracking device for recoil protons in {pi}{sup -}p interactions. We describe the chamber`s design considerations, details of its construction, electronics, and performance characteristics. (orig.).

  13. Trigger drift chamber for the MKII upgrade at PEP

    International Nuclear Information System (INIS)

    Ford, W.T.

    1984-06-01

    The design and fabrication work for the small trigger drift chamber are now advanced enough to permit a fairly detailed specification of this device as it will appear for installation in the detector next fall. This note contains a description of the trigger chamber design

  14. Nonlinear heat and particle transport due to collisional drift waves

    Energy Technology Data Exchange (ETDEWEB)

    Nishi-kawa, K.I.; Hatori, T.; Terashima, Y.

    1977-03-01

    The nonlinear evolution of unstable modes which govern transport processes in magnetically confined plasmas were investigated. A nonlinear theory of unstable collisional drift wave, and the consequent nonlinear transport were extended to include electron and ion temperature gradients. Thermal transport properties are discussed and basic equations are given.

  15. Drift-reducing nozzles and their biological efficacy.

    Science.gov (United States)

    Nuyttens, D; Dhoop, M; De Blauwer, V; Hermann, O; Hubrechts, W; Mestdagh, I; Dekeyser, D

    2009-01-01

    In 2007 and 2008, field trials were carried out with different standard and drift-reducing nozzles in sugar beet, maize, chicory, Belgian endive (all herbicide applications), wheat (fungicide application) and potatoes (Haulm killing herbicide application). The effect of nozzle type (standard flat fan, low-drift flat fan, air injection), nozzle size (ISO 02, 03 and 04) and application volume on the biological efficacy was investigated. All applications were done using a plot sprayer with volume rates ranging from 160 to 320 l.ha(-1) at recommended dose rates with commonly used (mix of) plant protection products. For each crop, the experiments included four replicates in a randomized block design. Depending on the type of application, the efficacy was measured in terms of weed control, disease and yield level, percentage dead leaf and stem, etc. In a previous research, drift and droplet characteristics of the different techniques were measured. In general no important effect of application technique on biological efficacy was observed for the tested herbicide and fungicide applications within the interval of volume rates and droplet size tested. Drift-reducing nozzles performed similar as conventional nozzles under good spraying conditions and using a correct spray application technique.

  16. Modelling the effects of drifting macroalgae in coastal waters

    DEFF Research Database (Denmark)

    Canal Vergés, Paula; Jørgensen, Charlotte; Flindt, Mogens

    2009-01-01

    It is well-known that opportunistic macroalgae starts to drift at low current velocities (Flindt et al. 2007) and that the nutrient transport in many aquatic systems are dominated by this process. New studies have shown, that at this current velocities, macroalgae moves as bedload transport creat...... obtained by flume experiments and field observations in protected and semi-protected shallow estuarine waters....

  17. Drift turbulence of plasma as a gas of vortex ensemble

    International Nuclear Information System (INIS)

    Aburdzhaniya, G.

    1989-01-01

    This paper shows that in the magnetoactive plasma the short-wavelength nonlinear vortex structures can form the drift turbulence. It has been established that the vortex structures, interacting between and with plasma particles, exite the wide density pulsation spectrum and lead to the anomalous diffusion of the particles. (author). 28 refs

  18. Curvature-induced electrostatic drift modes in a toroidal plasma

    International Nuclear Information System (INIS)

    Venema, M.

    1985-01-01

    This thesis deals with a number of problems in the theory of linear stability of a hot, fully ionized plasma immersed in a strong magnetic field. The most widely used system to magnetically confine a plasma is the tokamak. This is a toroidal, current carrying device with a strong, externally imposed, magnetic field. The author discusses the linear theory of unstable, low-frequency waves in the gradient region, restricted to electrostatic waves. In that case the resulting radial fluxes of particles and energy are due to electric cross-field drifts. In the presence of magnetic fluctuations and small-scale reconnection phenomena, radial transport could also be predominantly along field lines. At present, it is not clear which of the two mechanisms is the dominant feature of the observed anomalous transport. First, the author introduces the theory of drift waves in toroidal geometry. Next, the electrostratic drift modes in toroidal geometry (weakly collisional regime), the equations for low-frequency waves in the strongly collisional regime and the electrostatic drift modes (strongly collisional regime) are discussed. (Auth.)

  19. Effect of repository underground ventilation on emplacement drift temperature control

    International Nuclear Information System (INIS)

    Yang, H.; Sun, Y.; McKenzie, D.G.; Bhattacharyya, K.K.

    1996-01-01

    The repository advanced conceptual design (ACD) is being conducted by the Civilian Radioactive Waste Management System, Management ampersand Operating Contractor. Underground ventilation analyses during ACD have resulted in preliminary ventilation concepts and design methodologies. This paper discusses one of the recent evaluations -- effects of ventilation on emplacement drift temperature management

  20. Preliminary test for the aging effects of drift chambers

    International Nuclear Information System (INIS)

    MA Ji-Mao; WANG Yun-Yong; MAO Ze-Fe; LU Xin-Hua; XIE Pei-Pei; YAN Jie

    1985-01-01

    The degradation of some performance characteristics of drift chambers irradiated with a 5 MeV electron beam was tested. The gas mixtures Ar/CO 2 , Ar/CH 4 , and Ar/ iC 4 H 10 were used. The dark current, the pulse height, the energy resolution and the counting rate plateau were measured during the irradiation

  1. Littoral drift computations on mutual wave and current influence

    NARCIS (Netherlands)

    Bijker, E.W.

    1971-01-01

    11th Conference on Coastal Engineering in London 1968, the author presented a method for computing the littoral drift starting from the longshore current velocity as this is generated by the waves and with the assumption that the material is stirred up by the waves. In this paper measurements in a

  2. The CERES/NA45 Radial Drift Time Projection Chamber

    Czech Academy of Sciences Publication Activity Database

    Adamová, Dagmar; Agakichiev, G.; Antonczyk, D.; Appelshäuser, H.; Belaga, V.; Bielčík, J.; Braun-Munzinger, P.; Campagnolo, R.; Cherlin, A.; Damjanović, S.; Dietel, T.; Dietrich, L.; Drees, A.; Dubitzky, W.; Esumi, S.I.; Filimonov, K.; Fraenkel, Z.; Garabatos, C.; Glassel, P.; Hering, G.; Holeczek, J.; Kushpil, Vasilij; Marin, A.; Milosevic, J.; Milov, A.; Miskowiec, D.; Musa, L.; Panebrattsev, Y.; Pechenova, O.; Petráček, Vojtěch; Pfeiffer, A.; Rak, Jan; Ravinovich, I.; Richter, M.; Sako, H.; Schafer, E.; Schmitz, W.; Schukraft, J.; Seipp, W.; Sharma, A.; Shimansky, S.; Stachel, J.; Šumbera, Michal; Tilsner, H.; Tserruya, I.; Wessels, J. P.; Wienold, T.; Windelband, B.; Wurm, J.P.; Xie, W.; Yurevich, S.; Yurevich, V.

    2008-01-01

    Roč. 593, č. 3 (2008), s. 203-231 ISSN 0168-9002 R&D Projects: GA MŠk 1P04LA211 Institutional research plan: CEZ:AV0Z10480505 Keywords : radial drift TPC * field cage * pad plane Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.019, year: 2008

  3. 50 CFR 660.713 - Drift gillnet fishery.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Drift gillnet fishery. 660.713 Section 660.713 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES Highly Migratory Fisheries...

  4. Metocean input data for drift models applications: Loustic study

    International Nuclear Information System (INIS)

    Michon, P.; Bossart, C.; Cabioc'h, M.

    1995-01-01

    Real-time monitoring and crisis management of oil slicks or floating structures displacement require a good knowledge of local winds, waves and currents used as input data for operational drift models. Fortunately, thanks to world-wide and all-weather coverage, satellite measurements have recently enabled the introduction of new methods for the remote sensing of the marine environment. Within a French joint industry project, a procedure has been developed using basically satellite measurements combined to metocean models in order to provide marine operators' drift models with reliable wind, wave and current analyses and short term forecasts. Particularly, a model now allows the calculation of the drift current, under the joint action of wind and sea-state, thus radically improving the classical laws. This global procedure either directly uses satellite wind and waves measurements (if available on the study area) or indirectly, as calibration of metocean models results which are brought to the oil slick or floating structure location. The operational use of this procedure is reported here with an example of floating structure drift offshore from the Brittany coasts

  5. Exploring Ethical Dilemmas Using the "Drifting Goals" Archetype

    Science.gov (United States)

    Bardoel, E. Anne; Haslett, Tim

    2006-01-01

    This article demonstrates how the system archetype "drifting goals" can be used in the classroom to explore ethical dilemmas. System archetypes provide a framework that shifts the focus from seeing ethical dilemmas as stemming solely from the acts of individuals to exploring the systemic structures that are responsible for generic patterns of…

  6. CZT drift strip detectors for high energy astrophysics

    DEFF Research Database (Denmark)

    Kuvvetli, Irfan; Budtz-Jørgensen, Carl; Caroli, E.

    2010-01-01

    Requirements for X- and gamma ray detectors for future High Energy Astrophysics missions include high detection efficiency and good energy resolution as well as fine position sensitivity even in three dimensions.We report on experimental investigations on the CZT drift detector developed DTU Spac...

  7. Post Earnings Announcement Drift : More Risk than Investors can Bear

    NARCIS (Netherlands)

    Suijs, J.P.M.

    2002-01-01

    This paper shows how post earnings announcement drift may arise in a capital market with rational investors if the firm's earnings in consecutive periods are positively correlated and there is a fixed supply of the firm's shares.This result is driven by the fact that equilibrium share prices depend

  8. Plasma particle drifts due to traveling waves with cyclotron frequencies

    International Nuclear Information System (INIS)

    Hatakeyama, Rikizo; Sato, Naoyuki; Sato, Noriyoshi

    1991-01-01

    A particle orbit theory yields that traveling waves with cyclotron frequencies give rise to charged particle drifts perpendicular both to the wave propagation and external magnetic field lines. The result is applicable to particle-flux control of magnetized plasmas. (author)

  9. First experimental tests of a lead glass drift calorimeter

    International Nuclear Information System (INIS)

    Guerra, A.D.; Bellazzini, R.; Conti, M.; Massai, M.M.; Schwartz, G.; Habel, R.; Mulera, T.; Perez-Mendez, V.

    1985-10-01

    We are building a drift collection calorimeter, which has a combined radiator and electric field shaping structure made of fused lead glass tubing, treated in a H 2 reducing atmosphere. We describe the construction detail of the calorimeter and the experimental measurements on several prototypes with radioative sources and minimum ionizing particles. 9 refs., 11 figs

  10. Drift chamber vertex detectors for SLC/LEP

    International Nuclear Information System (INIS)

    Hayes, K.G.

    1987-03-01

    The short but measurable lifetimes of the b and c quarks and the tau lepton have motivated the development of high precision tracking detectors capable of providing information on the decay vertex topology of events containing these particles. This paper reviews the OPAL, L3, and MARK II experiments vertex drift chambers

  11. Drift-Scale Coupled Processes (DST and THC Seepage) Models

    Energy Technology Data Exchange (ETDEWEB)

    P. Dixon

    2004-04-05

    The purpose of this Model Report (REV02) is to document the unsaturated zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrological-chemical (THC) processes on UZ flow and transport. This Model Report has been developed in accordance with the ''Technical Work Plan for: Performance Assessment Unsaturated Zone'' (Bechtel SAIC Company, LLC (BSC) 2002 [160819]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this Model Report in Section 1.12, Work Package AUZM08, ''Coupled Effects on Flow and Seepage''. The plan for validation of the models documented in this Model Report is given in Attachment I, Model Validation Plans, Section I-3-4, of the TWP. Except for variations in acceptance criteria (Section 4.2), there were no deviations from this TWP. This report was developed in accordance with AP-SIII.10Q, ''Models''. This Model Report documents the THC Seepage Model and the Drift Scale Test (DST) THC Model. The THC Seepage Model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral alteration on flow in rocks surrounding drifts. The DST THC model is a drift-scale process model relying on the same conceptual model and much of the same input data (i.e., physical, hydrological, thermodynamic, and kinetic) as the THC Seepage Model. The DST THC Model is the primary method for validating the THC Seepage Model. The DST THC Model compares predicted water and gas compositions, as well as mineral alteration patterns, with observed data from the DST. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal-loading conditions, and predict the evolution of mineral alteration and fluid chemistry around potential waste emplacement drifts. The

  12. Drift-Scale Coupled Processes (DST and THC Seepage) Models

    Energy Technology Data Exchange (ETDEWEB)

    E. Gonnenthal; N. Spyoher

    2001-02-05

    The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M and O) 2000 [153447]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M and O 2000 [153309]). These models include the Drift Scale Test (DST) THC Model and several THC seepage models. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal loading conditions, and predict the chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: (1) Performance Assessment (PA); (2) Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); (3) UZ Flow and Transport Process Model Report (PMR); and (4) Near-Field Environment (NFE) PMR. The work scope for this activity is presented in the TWPs cited above, and summarized as follows: continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data

  13. Assessing plant residue decomposition in soil using DRIFT spectroscopy

    Science.gov (United States)

    Ouellette, Lance; Van Eerd, Laura; Voroney, Paul

    2016-04-01

    Assessment of the decomposition of plant residues typically involves the use of tracer techniques combined with measurements of soil respiration. This laboratory study evaluated use of Diffuse Reflectance Fourier Transform (DRIFT) spectroscopy for its potential to assess plant residue decomposition in soil. A sandy loam soil (Orthic Humic Gleysol) obtained from a field research plot was passed through a 4.75 mm sieve moist (~70% of field capacity) to remove larger crop residues. The experimental design consisted of a randomized complete block with four replicates of ten above-ground cover crop residue-corn stover combinations, where sampling time was blocked. Two incubations were set up for 1) Drift analysis: field moist soil (250 g ODW) was placed in 500 mL glass jars, and 2) CO2 evolution: 100 g (ODW) was placed in 2 L jars. Soils were amended with the plant residues (oven-dried at 60°C and ground to <2 mm) at rates equivalent to field mean above-ground biomass yields, then moistened to 60% water holding capacity and incubated in the dark at 22±3°C. Measurements for DRIFT and CO2-C evolved were taken after 0.5, 2, 4, 7, 10, 15, 22, 29, 36, 43, 50 64 and 72 d. DRIFT spectral data (100co-added scans per sample) were recorded with a Varian Cary 660 FT-IR Spectrometer equipped with an EasiDiff Diffuse Reflectance accessory operated at a resolution of 4 cm-1 over the mid-infrared spectrum from 4000 to 400 cm-1. DRIFT spectra of amended soils indicated peak areas of aliphatics at 2930 cm-1, of aromatics at 1620, and 1530 cm-1 and of polysaccharides at 1106 and 1036 cm-1. Evolved CO2 was measured by the alkali trap method (1 M NaOH); the amount of plant residue-C remaining in soil was calculated from the difference in the quantity of plant residue C added and the additional CO2-C evolved from the amended soil. First-order model parameters of the change in polysaccharide peak area over the incubation were related to those generated from the plant residue C decay

  14. SOI LDMOSFET with Up and Down Extended Stepped Drift Region

    Science.gov (United States)

    Saremi, Mehdi; Saremi, Masoumeh; Niazi, Hamid; Saremi, Maryam; Goharrizi, Arash Yazdanpanah

    2017-10-01

    To increase the breakdown voltage and decrease the ON resistance, a silicon-on-insulator (SOI) lateral double-diffused metal-oxide-semiconductor field-effect transistor (LDMOSFET) in which the drift region extends to the up and down oxides in a step shape is proposed. This up and down extended stepped drift SOI (UDESD-SOI) structure demonstrates a modified lateral electric field distribution with additional peaks as well as a decrease of the usual peaks near the drain and gate. Two-dimensional (2D) simulations were used to compare the characteristics of the proposed UDESD-SOI structure with those of other structures, viz. down extended stepped drift SOI (DESD-SOI), up extended stepped drift SOI (UESD-SOI), and conventional SOI (C-SOI). Under the same conditions, the breakdown voltage of the UDESD-SOI structure was nearly 35%, 117%, and 318% higher compared with the DESD-SOI, UESD-SOI, and C-SOI structure, respectively. To determine the optimum parameters for the UDESD-SOI structure leading to the highest breakdown voltage, a comparative study was performed to investigate the effect of the doping concentration in the drift region, buried oxide (BOX) thickness, and thickness of up and down extended steps ( T 1 and T 2, respectively). In addition, the drain current (ON resistance) of the UDESD-SOI structure was found to be 13%, 43%, and 229% higher (16%, 65%, and 257% lower) than the values for the DESD-SOI, UESD-SOI, and C-SOI structure, respectively.

  15. Evaluation of Potential Impacts of Microbial Activity on Drift Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Y. Wang

    2004-11-18

    ''Evaluation of Potential Impacts of Microbial Activity on Drift Chemistry'' focuses on the potential for microbial communities that could be active in repository emplacement drifts to influence the in-drift bulk chemical environment. This report feeds analyses to support the inclusion or exclusion of features, events, and processes (FEPs) in the total system performance assessment (TSPA) for the license application (LA), but this work is not expected to generate direct feeds to the TSPA-LA. The purpose was specified by, and the evaluation was performed and is documented in accordance with, ''Technical Work Plan For: Near-Field Environment and Transport In-Drift Geochemistry Analyses'' (BSC 2004 [DIRS 172402], Section 2.1). This report addresses all of the FEPs assigned by the technical work plan (TWP), including the development of exclusion arguments for FEPs that are not carried forward to the TSPA-LA. Except for an editorial correction noted in Section 6.2, there were no other deviations from the TWP. This report documents the completion of all assigned tasks, as follows (BSC 2004 DIRS 172402, Section 1.2.1): (1) Perform analyses to evaluate the potential for microbial activity in the waste emplacement drift under the constraints of anticipated physical and chemical conditions. (2) Evaluate uncertainties associated with these analyses. (3) Determine whether the potential for microbes warrants a feed to TSPA-LA to account for predicted effects on repository performance. (4) Provide information to address the ''Yucca Mountain Review Plan, Final Report'' (NUREG-1804) (NRC 2003 [DIRS 163274]) and Key Technical Issues and agreements, as appropriate. (5) Develop information for inclusion or exclusion of FEPs.

  16. Evaluation of Potential Impacts of Microbial Activity on Drift Chemistry

    International Nuclear Information System (INIS)

    Y. Wang

    2004-01-01

    ''Evaluation of Potential Impacts of Microbial Activity on Drift Chemistry'' focuses on the potential for microbial communities that could be active in repository emplacement drifts to influence the in-drift bulk chemical environment. This report feeds analyses to support the inclusion or exclusion of features, events, and processes (FEPs) in the total system performance assessment (TSPA) for the license application (LA), but this work is not expected to generate direct feeds to the TSPA-LA. The purpose was specified by, and the evaluation was performed and is documented in accordance with, ''Technical Work Plan For: Near-Field Environment and Transport In-Drift Geochemistry Analyses'' (BSC 2004 [DIRS 172402], Section 2.1). This report addresses all of the FEPs assigned by the technical work plan (TWP), including the development of exclusion arguments for FEPs that are not carried forward to the TSPA-LA. Except for an editorial correction noted in Section 6.2, there were no other deviations from the TWP. This report documents the completion of all assigned tasks, as follows (BSC 2004 DIRS 172402, Section 1.2.1): (1) Perform analyses to evaluate the potential for microbial activity in the waste emplacement drift under the constraints of anticipated physical and chemical conditions. (2) Evaluate uncertainties associated with these analyses. (3) Determine whether the potential for microbes warrants a feed to TSPA-LA to account for predicted effects on repository performance. (4) Provide information to address the ''Yucca Mountain Review Plan, Final Report'' (NUREG-1804) (NRC 2003 [DIRS 163274]) and Key Technical Issues and agreements, as appropriate. (5) Develop information for inclusion or exclusion of FEPs

  17. Pulsar bi-drifting: implications for polar cap geometry

    Science.gov (United States)

    Wright, Geoff; Weltevrede, Patrick

    2017-01-01

    For many years it has been considered puzzling how pulsar radio emission, supposedly created by a circulating carousel of sub-beams, can produce the drift bands demonstrated by PSR J0815+0939, and more recently PSR B1839-04, which simultaneously drifts in opposing directions. Here, we suggest that the carousels of these pulsars, and hence their beams, are not circular but elliptical with axes tilted with respect to the fiducial plane. We show that certain relatively unusual lines of sight can cause bi-drifting to be observed, and a simulation of the two known exemplars is presented. Although bi-drifting is rare, non-circular beams may be common among pulsars and reveal themselves by having profile centroids displaced from the fiducial plane identified by polarization position angle swings. They may also result in profiles with asymmetric- and frequency-dependent component evolution. It is further suggested that the carousels may change their tilt by specific amounts and later reverse them. This may occur suddenly, accompanying a mode change (e.g. PSR B0943+10), or more gradually and short lived as in `flare' pulsars (e.g. PSR B1859+07). A range of pulsar behaviour (e.g. the shifting drift patterns of PSRs B0818-41 and B0826-34) may also be the result of non-circular carousels with varying orientation. The underlying nature of these carousels - whether they are exclusively generated by polar cap physics or driven by magnetospheric effects - is briefly discussed.

  18. Plant reproduction is altered by simulated herbicide drift toconstructed plant communities

    Science.gov (United States)

    Herbicide drift may have unintended impacts on native vegetation, adversely affecting structure and function of plant communities. However, these potential effects have been rarely studied or quantified. To determine potential ecological effects of herbicide drift, we construct...

  19. Arctic Ocean Drift Tracks from Ships, Buoys and Manned Research Stations, 1872-1973

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Thirty-four drift tracks in the Arctic Ocean pack ice are collected in a unified tabular data format, one file per track. Data are from drifting ships, manned...

  20. Distance, dams and drift: What structures populations of an endangered, benthic stream fish?

    Science.gov (United States)

    Roberts, James H.; Angermeier, Paul; Hallerman, Eric M.

    2013-01-01

    Spatial population structure plays an important role in species persistence, evolution and conservation. Benthic stream fishes are diverse and frequently imperilled, yet the determinants and spatial scaling of their population structure are understudied. We investigated the range-wide population genetic structure of Roanoke logperch (Percina rex), an endangered, benthic stream fish of the eastern United States. Fish were sampled from 35 sites and analysed at 11 microsatellite DNA loci. Clustering models were used to sort individuals into genetically cohesive groups and thereby estimate the spatial scaling of population structure. We then used Bayesian generalized linear mixed models (BGLMMs) to test alternative hypotheses about the environmental factors most responsible for generating structure, as measured by the differentiation statistic FST. Clustering models delineated seven discrete populations, whose boundaries coincided with agents of fragmentation, including hydroelectric dams and tailwaters. In the absence of hydrological barriers, gene flow was extensive throughout catchments, whereas there was no evidence for contemporary dispersal between catchments across barriers. In the best-supported BGLMM, FST was positively related to the spatial distance and degree of hydrological alteration between sites and negatively related to genetic diversity within sites. Whereas the effect of tailwaters was equivocal, dams strongly influenced differentiation: the effect of a dam on FST was comparable to that of a between-site distance of over 1200 km of unimpounded river. Overall, the effect of distance-mediated dispersal was negligible compared to the combined effects of fragmentation and genetic drift. The contemporary population structure of P. rex comprises a few geographically extensive ‘islands’ that are fragmented by hydroelectric projects. This information clarifies the importance of a catchment-scale perspective on conserving the species and

  1. Search for the best timing strategy in high-precision drift chambers

    Energy Technology Data Exchange (ETDEWEB)

    Va' vra, J.

    1983-06-01

    Computer simulated drift chamber pulses are used to investigate various possible timing strategies in the drift chambers. In particular, the leading edge, the multiple threshold and the flash ADC timing methods are compared. Although the presented method is general for any drift geometry, we concentrate our discussion on the jet chambers where the drift velocity is about 3 to 5 cm/..mu..sec and the individual ionization clusters are not resolved due to a finite speed of our electronics.

  2. Search for the best timing strategy in high-precision drift chambers

    International Nuclear Information System (INIS)

    Va'vra, J.

    1983-06-01

    Computer simulated drift chamber pulses are used to investigate various possible timing strategies in the drift chambers. In particular, the leading edge, the multiple threshold and the flash ADC timing methods are compared. Although the presented method is general for any drift geometry, we concentrate our discussion on the jet chambers where the drift velocity is about 3 to 5 cm/μsec and the individual ionization clusters are not resolved due to a finite speed of our electronics

  3. WARM JUPITERS NEED CLOSE ''FRIENDS'' FOR HIGH-ECCENTRICITY MIGRATION—A STRINGENT UPPER LIMIT ON THE PERTURBER'S SEPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Subo [Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Road 5, Hai Dian District, Beijing 100871 (China); Katz, Boaz; Socrates, Aristotle [Institute for Advanced Study, 1 Einstein Dr., Princeton, NJ 08540 (United States)

    2014-01-20

    We propose a stringent observational test on the formation of warm Jupiters (gas-giant planets with 10 days ≲ P ≲ 100 days) by high-eccentricity (high-e) migration mechanisms. Unlike hot Jupiters, the majority of observed warm Jupiters have pericenter distances too large to allow efficient tidal dissipation to induce migration. To access the close pericenter required for migration during a Kozai-Lidov cycle, they must be accompanied by a strong enough perturber to overcome the precession caused by general relativity, placing a strong upper limit on the perturber's separation. For a warm Jupiter at a ∼ 0.2 AU, a Jupiter-mass (solar-mass) perturber is required to be ≲ 3 AU (≲ 30 AU) and can be identified observationally. Among warm Jupiters detected by radial velocities (RVs), ≳ 50% (5 out of 9) with large eccentricities (e ≳ 0.4) have known Jovian companions satisfying this necessary condition for high-e migration. In contrast, ≲ 20% (3 out of 17) of the low-e (e ≲ 0.2) warm Jupiters have detected additional Jovian companions, suggesting that high-e migration with planetary perturbers may not be the dominant formation channel. Complete, long-term RV follow-ups of the warm-Jupiter population will allow a firm upper limit to be put on the fraction of these planets formed by high-e migration. Transiting warm Jupiters showing spin-orbit misalignments will be interesting to apply our test. If the misalignments are solely due to high-e migration as commonly suggested, we expect that the majority of warm Jupiters with low-e (e ≲ 0.2) are not misaligned, in contrast with low-e hot Jupiters.

  4. Determination of selection criteria for spray drift reduction from atomization data

    Science.gov (United States)

    When testing and evaluating drift reduction technologies (DRT), there are different metrics that can be used to determine if the technology reduces drift as compared to a reference system. These metrics can include reduction in percent of fine drops, measured spray drift from a field trial, or comp...

  5. Noncontact measurement of electrostatic fields: Verification of modeled potentials within ion mobility spectrometer drift tube designs

    International Nuclear Information System (INIS)

    Scott, Jill R.; Tremblay, Paul L.

    2007-01-01

    The heart of an ion mobility spectrometer is the drift region where ion separation occurs. While the electrostatic potentials within a drift tube design can be modeled, no method for independently validating the electrostatic field has previously been reported. Two basic drift tube designs were modeled using SIMION 7.0 to reveal the expected electrostatic fields: (1) A traditional alternating set of electrodes and insulators and (2) a truly linear drift tube. One version of the alternating electrode/insulator drift tube and two versions of linear drift tubes were then fabricated. The stacked alternating electrodes/insulators were connected through a resistor network to generate the electrostatic gradient in the drift tube. The two linear drift tube designs consisted of two types of resistive drift tubes with one tube consisting of a resistive coating within an insulating tube and the other tube composed of resistive ferrites. The electrostatic fields within each type of drift tube were then evaluated by a noncontact method using a Kelvin-Zisman type electrostatic voltmeter and probe (results for alternative measurement methods provided in supplementary material). The experimental results were then compared with the electrostatic fields predicted by SIMION. Both the modeling and experimental measurements reveal that the electrostatic fields within a stacked ion mobility spectrometer drift tube are only pseudo-linear, while the electrostatic fields within a resistive drift tube approach perfect linearity

  6. Wind tunnel measurements and model predictions for estimating spray drift reduction under field conditions

    NARCIS (Netherlands)

    Butler Ellis, M.C.; Alanis, R.; Lane, A.G.; Tuck, C.R.; Nuyttens, D.; Zande, van de J.C.

    2017-01-01

    A UK scheme to enable the protection of surface water from spray drift allows farmers to reduce the size of a buffer zone according to the drift-reducing capability of the sprayer. Recent changes to UK regulations have allowed buffer zones greater than 6 m to be included, providing that 75% drift

  7. Drift-wave turbulence and zonal flow generation

    International Nuclear Information System (INIS)

    Balescu, R.

    2003-01-01

    Drift-wave turbulence in a plasma is analyzed on the basis of the wave Liouville equation, describing the evolution of the distribution function of wave packets (quasiparticles) characterized by position x and wave vector k. A closed kinetic equation is derived for the ensemble-averaged part of this function by the methods of nonequilibrium statistical mechanics. It has the form of a non-Markovian advection-diffusion equation describing coupled diffusion processes in x and k spaces. General forms of the diffusion coefficients are obtained in terms of Lagrangian velocity correlations. The latter are calculated in the decorrelation trajectory approximation, a method recently developed for an accurate measure of the important trapping phenomena of particles in the rugged electrostatic potential. The analysis of individual decorrelation trajectories provides an illustration of the fragmentation of drift-wave structures in the radial direction and the generation of long-wavelength structures in the poloidal direction that are identified as zonal flows

  8. Carrier-envelope Phase Drift Detection of Picosecond Pulses

    Directory of Open Access Journals (Sweden)

    Cormier E.

    2013-03-01

    Full Text Available A bandwidth-independent, linear and scalable method for carrier-envelope phase drift measurement demonstrated. Our experiments reveal that carrier-envelope phase drift of a picosecond pulse train can be directly obtained from the spectrally resolved interference pattern of a length-stabilized multiple-beam interferometer. The retrieved phase from the pattern correlates well with the strongly CEP-sensitive coupling signal between the frequency combs of the picosecond oscillator and an ultra-high finesse Fabry-Perot interferometer. Our results can lead to the generation of a robust CEP-stabilized seed pulse train for high resolution comb spectroscopy as well as to compact Compton X-ray and gamma-ray sources

  9. Analytical solutions for space charge fields in TPC drift volumes

    CERN Document Server

    Rossegger, S; Schnizer, B

    2011-01-01

    At high particle rates and high multiplicities, Time Projection Chambers can suffer from field distortions due to slow moving ions that accumulate within the drift volume. These variations modify the electron trajectory along the drift path, affecting the tracking performance of the detector. In order to calculate the track distortions due to an arbitrary space charge distribution in a TPC, novel representations of the Green's function for a TPC-like geometry were worked out. This analytical approach permits accurate predictions of track distortions due to an arbitrary space charge distribution (by solving the Langevin equation) as well as the possibility to benchmark common numerical methods to calculate such space charge fields. (C) 2011 Elsevier B.V. All rights reserved.

  10. Advanced AEM by Comprehensive Analysis and Modeling of System Drift

    Science.gov (United States)

    Schiller, Arnulf; Klune, Klaus; Schattauer, Ingrid

    2010-05-01

    The quality of the assessment of risks outgoing from environmental hazards strongly depends on the spatial and temporal distribution of the data collected in a survey area. Natural hazards generally emerge from wide areas as it is in the case of volcanoes or land slides. Conventional surface measurements are restricted to few lines or locations and often can't be conducted in difficult terrain. So they only give a spatial and temporary limited data set and therefore limit the reliability of risk analysis. Aero-geophysical measurements potentially provide a valuable tool for completing the data set as they can be performed over a wide area, even above difficult terrain within a short time. A most desirable opportunity in course of such measurements is the ascertainment of the dynamics of such potentially hazardous environmental processes. This necessitates repeated and reproducible measurements. Current HEM systems can't accomplish this adequately due to their system immanent drift and - in some cases - bad signal to noise ratio. So, to develop comprising concepts for advancing state of the art HEM-systems to a valuable tool for data acquisition in risk assessment or hydrological problems, different studies have been undertaken which form the contents of the presented work conducted in course of the project HIRISK (Helicopter Based Electromagnetic System for Advanced Environmental Risk Assessment - FWF L-354 N10, supported by the Austrian Science Fund). The methodology is based upon two paths: A - Comprehensive experimental testing on an existing HEM system serving as an experimental platform. B - The setup of a numerical model which is continuously refined according to the results of the experimental data. The model then serves to simulate the experimental as well as alternative configurations and to analyze them subject to their drift behavior. Finally, concepts for minimizing the drift are derived and tested. Different test series - stationary on ground as well

  11. Feasibility tests of a high resolution sampling radial drift chamber

    International Nuclear Information System (INIS)

    Huth, J.

    1985-01-01

    The design concept and results of feasibility tests for a vertex detector intended for use in the TPC-PEP4/9 experiment are presented. The detector is based on a slow radial drift in dimethyl ether. High resolution localization of the avalanches at the sense wire is accomplished with nearby pickup wires and the utilization of waveform sampling electronics. The avalanche angular coordinate measurements, combined with knowledge of the electric field distribution and drift velocity permit reconstruction of the trajectory using essentially all track information. Measurements with a test chamber constructed to study characteristics of avalanche localization indicate that the recoverable track information in one centimeter of dimethyl ether at 1.5 atm is equivalent to 30 measurements of 40 μm accuracy. (orig.)

  12. In situ DRIFTS study of hygroscopic behavior of mineral aerosol.

    Science.gov (United States)

    Ma, Qingxin; He, Hong; Liu, Yongchun

    2010-01-01

    In situ diffusion reflectance infrared Fourier transform spectroscopy was used to study the water adsorption on mineral oxides (SiO2, alpha-Al2O3, MgO, Fe2O3, TiO2). The results showed that all the water adsorption isotherms were well fitted with the Brunauer-Emmett-Teller (BET)-III type equation, with the calculated monolayers occurring at 24%-30% relative humidity. It showed that about 1-5 layers of water adsorbed on oxides surfaces in ambient relative humidity (20%-90%). The measured deliquescence relative humidity of NaCl was (74 +/- 1)%, which demonstrated that DRIFTS is a useful method for the study the hygroscopic behavior of mineral dust. In addition, the limits of DRIFTS were also discussed.

  13. Nonlinear heat and particle transport due to collisional drift waves

    Energy Technology Data Exchange (ETDEWEB)

    Nishi-Kawa, K.I.; Hatori, T.; Terashima, Y.

    1978-07-01

    A nonlinear analysis of collisional drift instability is developed in a slab model based on the two fluid equations, where inhomogeneities in electron and ion temperatures and unperturbed current are included in addition to ion inertia, finite ion gyroradius, and viscosity. A systematic expansion is introduced by taking epsilon=vertical-barkappavertical-barl as a smallness parameter, where kappa is the degree of density gradient and l is the linear scale of the slab along the density gradient. The nonlinear development of the drift wave near marginal stability is studied on the basis of the model equations. A new feature, hard excitation, has been found, which is due to the effects of the nonlinear frequency shift and the electron temperature gradient. The saturation amplitude is calculated, and the expressions for wave-associated particle and heat fluxes are obtained. A comparison of the expressions with the experimental results of a stellerator device is also made.

  14. Silicon drift chamber studies for the RHIC STAR experiment

    International Nuclear Information System (INIS)

    Humanic, T.J.

    1992-01-01

    The two-hit resolution of a silicon drift chamber is measured using a pulsed Nd:Yag laser and a time digitizer readout. The data is analyzed by forming the covariance matrix in time samples, and transforming to a matrix in amplitude and time variation of each of the two hits. The resolution of the two-hit separation is found to be better than 25 microns with a drift field of 530 V/cm and a separation of more than 500 microns, with the resolution increasing to 50 microns as the separation nears 500 microns. Results are also presented for multiply ionizing tracks, showing a great improvement over single minimum ionizing. 8 refs

  15. Prediction of pool void fraction by new drift flux correlation

    International Nuclear Information System (INIS)

    Kataoka, I.; Ishii, M.

    1986-06-01

    A void fraction for a bubbling or boiling pool system is one of the important parameters in analyzing heat and mass transfer processes. Using the drift flux formulation, correlations for the pool void fraction have been developed in collaboration with a large number of experimental data. It has been found that the drift velocity in a pool system depends upon vessel diameter, system pressure, gas flux and fluid physical properties. The results show that the relative velocity and void fraction can be quite different from those predicted by conventional correlations. In terms of the rise velocity, four different regimes are identified. These are bubbly, churn-turbulent, slug and cap bubble regimes. The present correlations are shown to agree with the experimental data over wide ranges of parameters such as vessel diameter, system pressure, gas flux and physical properties. 39 refs., 41 figs

  16. Modeling Influenza Antigenic Shift and Drift with LEGO Bricks

    Directory of Open Access Journals (Sweden)

    Boriana Marintcheva

    2016-05-01

    Full Text Available The concepts of antigenic shift and drift could be found in almost every microbiology and virology syllabus, usually taught in the context of Influenza virus biology. They are central to understanding viral diversity and evolution and have direct application to anti-flu vaccine design and effectiveness. To aid student understanding of the concepts, I have developed an exercise to visualize the mechanistic aspects of antigenic shift and drift using LEGO bricks. This hands-on/minds-on exercise asks students to replicate viruses taking into account the error-prone nature of Influenza RNA polymerase and to package model virions from a host cell infected with two different Influenza strains, while keeping track of the level of diversity of newly propagated viral particles. The exercise can be executed in any type of classroom for about 10 minutes and if desired, extended to emphasize quantitative skills, molecular biology concepts, or to trigger discussion of key issues in vaccine design.

  17. Impact of centrifugal drifts on ion turbulent transport

    Science.gov (United States)

    Belli, E. A.; Candy, J.

    2018-03-01

    The influence of sonic toroidal rotation on gyrokinetic stability and transport is studied, with important implications for heavy impurity dynamics. When centrifugal drifts and electrostatic trapping corrections are included, significant modifications to the calculated transport of heavy impurities are observed. These high-rotation corrections add to the standard Coriolis drift and toroidal rotation shear drive which are normally included in gyrokinetics. Yet, because of their complexity, centrifugal and electrostatic trapping terms (quadratic in the main ion Mach number) are not generally included in gyrokinetic codes. In this work, we explore the implications of using reduced descriptions of the rotational physics. For heavy impurities such as tungsten, cross terms due to the centrifugal force can dominate the rotation dynamics, and neglecting them is shown to lead to large errors in the impurity particle flux.

  18. Symbol interval optimization for molecular communication with drift.

    Science.gov (United States)

    Kim, Na-Rae; Eckford, Andrew W; Chae, Chan-Byoung

    2014-09-01

    In this paper, we propose a symbol interval optimization algorithm in molecular communication with drift. Proper symbol intervals are important in practical communication systems since information needs to be sent as fast as possible with low error rates. There is a trade-off, however, between symbol intervals and inter-symbol interference (ISI) from Brownian motion. Thus, we find proper symbol interval values considering the ISI inside two kinds of blood vessels, and also suggest no ISI system for strong drift models. Finally, an isomer-based molecule shift keying (IMoSK) is applied to calculate achievable data transmission rates (achievable rates, hereafter). Normalized achievable rates are also obtained and compared in one-symbol ISI and no ISI systems.

  19. Performance of the CMS Drift Tube Chambers with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; 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    2010-01-01

    Studies of the performance of the CMS drift tube barrel muon system are described, with results based on data collected during the CMS Cosmic Run at Four Tesla. For most of these data, the solenoidal magnet was operated with a central field of 3.8 T. The analysis of data from 246 out of a total of 250 chambers indicates a very good muon reconstruction capability, with a coordinate resolution for a single hit of about 260 microns, and a nearly 100% efficiency for the drift tube cells. The resolution of the track direction measured in the bending plane is about 1.8 mrad, and the efficiency to reconstruct a segment in a single chamber is higher than 99%. The CMS simulation of cosmic rays reproduces well the performance of the barrel muon detector.

  20. Monitoring of sea ice drift and area flux in the Fram Strait

    Science.gov (United States)

    Sandven, S.; Kloster, K.; Wåhlin, J.

    2009-04-01

    The western part of the Fram strait is normally covered with sea ice throughout the year. The ice is stationary as fast ice out to 70 -140km from the Greenland coast. Outside is a zone with drifting ice with a gradual increase in drift speed further eastwards to the centre of the strait. Since 2004 NERSC has used ENVISAT ASAR Wideswath images with 150 m resolution to estimate ice drift with three days interval. To resolve the zonal variability in the ice drift field, strait is divided into four different zones. Zone I has usually fastice, zone II is the transition zone with a zonal ice drift gradient, Zone III is only drifting ice and zone IV includes the shelf break and the marginal ice zone where the ice drift is normally at a maximum. This is zone is also more difficult for ice drift for ice drift retrieval from satellites because of quite homogeneous ice cover. The ice area flux is calculated from the detailed ice drift- and concentration-profiles at 79N, as the integral in longitude of the product of ice concentration and ice displacement. The data shows an increased ice flux over the last four seasons since 2004-05. The SAR derived ice drift data are compared with similar ice drift data from AMSRE and merged QuikScat and SSMI data for the winter season October to April when passive microwave and scatterometer data can be used for ice drift retrieval. The comparison shows that the SAR data resolves the zonal structure and gives a general higher ice drift compared the other data sets. SAR also provides year-round data on ice drift, which allows a more precise estimation of monthly and annual ice area fluxes. The study is supported by the DAMOCLES project.